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  Subjects -> HISTORY (Total: 1265 journals)
    - HISTORY (798 journals)
    - History (General) (51 journals)
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HISTORY (798 journals)                  1 2 3 4 | Last

Showing 1 - 200 of 452 Journals sorted alphabetically
40 [degrees] South     Full-text available via subscription   (Followers: 2)
Aboriginal History     Full-text available via subscription   (Followers: 6)
Abstracta Iranica     Open Access   (Followers: 13)
Acadiensis : Journal of the History of the Atlantic Region / Acadiensis : revue d'histoire de la region Atlantique     Full-text available via subscription   (Followers: 4)
Accounting History Review     Hybrid Journal   (Followers: 17)
Acta Amazonica     Open Access   (Followers: 3)
Acta Historiae Artium     Full-text available via subscription   (Followers: 4)
Acta Orientalia     Full-text available via subscription   (Followers: 16)
Actes d'Història de la Ciència i de la Tècnica     Open Access  
Advances in Historical Studies     Open Access   (Followers: 3)
Advances in Software Engineering     Open Access   (Followers: 10)
Africa Confidential     Hybrid Journal   (Followers: 18)
Africa Research Bulletin: Political, Social and Cultural Series     Hybrid Journal   (Followers: 9)
Africa Today     Full-text available via subscription   (Followers: 17)
African and Asian Studies     Hybrid Journal   (Followers: 19)
African Diaspora     Open Access   (Followers: 8)
African Historical Review     Hybrid Journal   (Followers: 15)
African Natural History     Open Access   (Followers: 1)
Agora     Full-text available via subscription   (Followers: 3)
Agricultural History Review     Full-text available via subscription   (Followers: 9)
Akroterion     Full-text available via subscription   (Followers: 4)
Al-Masaq: Islam and the Medieval Mediterranean     Hybrid Journal   (Followers: 27)
Almagest     Full-text available via subscription   (Followers: 1)
Altorientalische Forschungen     Hybrid Journal   (Followers: 6)
American Archivist     Hybrid Journal   (Followers: 144)
American Communist History     Hybrid Journal   (Followers: 18)
American Jewish History     Full-text available via subscription   (Followers: 15)
American Nineteenth Century History     Hybrid Journal   (Followers: 21)
American Periodicals : A Journal of History, Criticism, and Bibliography     Full-text available via subscription   (Followers: 7)
American Review of Canadian Studies     Hybrid Journal   (Followers: 6)
American Studies     Full-text available via subscription   (Followers: 20)
Amérique Latine Histoire et Mémoire     Open Access   (Followers: 2)
Amsterdamer Beitrage zur alteren Germanistik     Full-text available via subscription   (Followers: 3)
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Anais do Museu Paulista : História e Cultura Material     Open Access   (Followers: 1)
Analecta Bollandiana     Full-text available via subscription   (Followers: 2)
Anales de Historia del Arte     Open Access   (Followers: 6)
Anatolica     Full-text available via subscription   (Followers: 10)
Ancient Civilizations from Scythia to Siberia     Hybrid Journal   (Followers: 10)
Ancient History : Resources for Teachers     Full-text available via subscription   (Followers: 1)
Anglican Historical Society Journal     Full-text available via subscription   (Followers: 2)
Annales historiques de la Révolution française     Open Access   (Followers: 11)
Annales UMCS, Historia     Open Access   (Followers: 5)
Annali dell'Istituto e Museo di storia della scienza di Firenze     Hybrid Journal  
Annuaire de l'Ecole pratique des hautes etudes. Section des sciences historiques et philologiques     Open Access   (Followers: 9)
Annual Bulletin of Historical Literature     Hybrid Journal   (Followers: 12)
ANQ: A Quarterly Journal of Short Articles, Notes, and Reviews     Hybrid Journal   (Followers: 1)
Antike und Abendland     Hybrid Journal   (Followers: 10)
Antiteses     Open Access  
Anuario de Estudios Atlánticos     Open Access   (Followers: 1)
Anuario de Historia de la Iglesia     Open Access   (Followers: 3)
Arabian Humanities     Open Access   (Followers: 1)
Arabica     Hybrid Journal   (Followers: 8)
ARAM Periodical     Full-text available via subscription   (Followers: 3)
Araucaria. Revista Iberoamericana de Filosofía, Política y Humanidades     Open Access   (Followers: 1)
ArcheoArte. Rivista Elettronica di Archeologia e Arte     Open Access   (Followers: 6)
Architectural Heritage     Hybrid Journal   (Followers: 25)
Archive for History of Exact Sciences     Hybrid Journal   (Followers: 7)
Archives Internationales d'Histoire des Sciences     Partially Free   (Followers: 2)
Archives of Natural History     Hybrid Journal   (Followers: 7)
Area     Hybrid Journal   (Followers: 11)
Arenal. Revista de historia de las mujeres     Open Access  
Aristotelian Society Supplementary Volume     Hybrid Journal   (Followers: 2)
Arizona Journal of Hispanic Cultural Studies     Full-text available via subscription   (Followers: 3)
Art History     Hybrid Journal   (Followers: 189)
Arthuriana     Full-text available via subscription   (Followers: 5)
Arys: Antigüedad, Religiones y Sociedades     Open Access   (Followers: 1)
Aschkenas     Hybrid Journal   (Followers: 3)
Asia Pacific Business Review     Hybrid Journal   (Followers: 5)
Asia Pacific Journal of Education     Hybrid Journal   (Followers: 17)
Asia-Pacific Journal : Japan Focus     Open Access   (Followers: 6)
Asian Journal of Social Psychology     Hybrid Journal   (Followers: 5)
Asian Perspectives     Full-text available via subscription   (Followers: 9)
Asian Philosophy: An International Journal of the Philosophical Traditions of the East     Hybrid Journal   (Followers: 7)
Asian Studies Review     Hybrid Journal   (Followers: 17)
Aspasia     Full-text available via subscription  
Astérion     Open Access   (Followers: 1)
Ateliê de História UEPG     Open Access  
Aurora Journal     Full-text available via subscription  
Austral Ecology     Hybrid Journal   (Followers: 12)
Australasian Journal of Irish Studies, The     Full-text available via subscription   (Followers: 9)
Australasian Review of African Studies, The     Full-text available via subscription   (Followers: 2)
Australian Antarctic Magazine     Free   (Followers: 4)
Australian Cultural History     Hybrid Journal   (Followers: 11)
Australian Historical Studies     Hybrid Journal   (Followers: 13)
Australian Journal of Legal History     Full-text available via subscription   (Followers: 19)
Australian Journal of Politics & History     Hybrid Journal   (Followers: 13)
Balkanologie : Revue d'Études Pluridisciplinaires     Open Access   (Followers: 4)
Baltic-Pontic Studies     Open Access   (Followers: 1)
Behemoth     Open Access   (Followers: 3)
Berichte Zur Wissenschaftsgeschichte     Hybrid Journal   (Followers: 8)
BIBLOS - Revista do Departamento de Biblioteconomia e História     Open Access   (Followers: 13)
Biodiversity and Natural History     Open Access   (Followers: 5)
Biographical Memoirs of Fellows of the Royal Society     Full-text available via subscription   (Followers: 2)
Biography     Full-text available via subscription   (Followers: 17)
Bochumer Philosophisches Jahrbuch für Antike und Mittelalter     Hybrid Journal   (Followers: 2)
Body & Society     Hybrid Journal   (Followers: 21)
Boletim Cearense de Educação e História da Matemática     Open Access  
Book History     Full-text available via subscription   (Followers: 112)
Boom : A Journal of California     Full-text available via subscription   (Followers: 1)
Britain and the World     Hybrid Journal   (Followers: 9)
British Journal for Military History     Open Access   (Followers: 22)
British Journal of Canadian Studies     Hybrid Journal   (Followers: 10)
British Journal of Middle Eastern Studies     Hybrid Journal   (Followers: 23)
British Mycological Society Symposia Series     Full-text available via subscription   (Followers: 1)
British Review of New Zealand Studies     Full-text available via subscription   (Followers: 2)
Bryn Mawr Classical Review     Open Access   (Followers: 32)
BSHM Bulletin: Journal of the British Society for the History of Mathematics     Hybrid Journal   (Followers: 6)
Buildings & Landscapes: Journal of the Vernacular Architecture Forum     Full-text available via subscription   (Followers: 13)
Bulletin d'histoire politique     Full-text available via subscription   (Followers: 3)
Bulletin de la Sabix     Open Access  
Bulletin de Philosophie Medievale     Full-text available via subscription   (Followers: 5)
Bulletin du centre d’études médiévales d’Auxerre     Open Access   (Followers: 6)
Bulletin d’études Orientales     Open Access   (Followers: 10)
Bulletin of Hispanic Studies     Hybrid Journal   (Followers: 11)
Bulletin of Latin American Research     Hybrid Journal   (Followers: 15)
Bulletin of Spanish Studies: Hispanic Studies and Researches on Spain, Portugal and Latin America     Hybrid Journal   (Followers: 23)
Bulletin of the Ecological Society of America     Open Access   (Followers: 3)
Bulletin of the John Rylands Library     Hybrid Journal   (Followers: 12)
Bustan     Hybrid Journal   (Followers: 1)
Byzantine and Modern Greek Studies     Hybrid Journal   (Followers: 9)
Byzantinische Zeitschrift     Hybrid Journal   (Followers: 11)
Byzantion Nea Hellás     Open Access   (Followers: 2)
C@hiers du CRHIDI     Open Access  
Cabo     Full-text available via subscription  
Cadernos de História     Open Access  
CADUS - Revista de Estudos de Política, História e Cultura     Open Access  
Cahiers d'histoire     Full-text available via subscription   (Followers: 2)
Cahiers d'histoire. Revue d'histoire critique     Open Access   (Followers: 11)
Cahiers de l'Urmis     Open Access   (Followers: 1)
Cahiers des études anciennes     Open Access   (Followers: 7)
Cahiers du Centre de recherches historiques     Open Access   (Followers: 9)
Cahiers du Monde Russe     Open Access   (Followers: 10)
Cahiers d’études africaines     Open Access   (Followers: 9)
Cahiers « Mondes anciens »     Open Access   (Followers: 5)
California Italian Studies Journal     Full-text available via subscription   (Followers: 5)
Cambridge Journal of Regions, Economy and Society     Hybrid Journal   (Followers: 9)
Canadian Historical Review     Full-text available via subscription   (Followers: 10)
Canadian Journal of History     Full-text available via subscription   (Followers: 8)
Canadian Journal of Linguistics / La revue canadienne de linguistique     Full-text available via subscription   (Followers: 8)
Canadian Review of American Studies     Full-text available via subscription   (Followers: 1)
Canadian-American Slavic Studies     Hybrid Journal   (Followers: 7)
Caribbean Studies     Full-text available via subscription   (Followers: 10)
Catholic Historical Review     Full-text available via subscription   (Followers: 15)
Cemoti, Cahiers d'études sur la méditerranée orientale et le monde turco-iranien     Open Access   (Followers: 2)
Central Asian Survey     Hybrid Journal   (Followers: 8)
Central Europe     Hybrid Journal   (Followers: 4)
Chaucer Review     Full-text available via subscription   (Followers: 7)
Childhood in the Past : An International Journal     Hybrid Journal   (Followers: 3)
Chinese Studies in History     Full-text available via subscription   (Followers: 9)
Chronica Nova. Revista de Historia Moderna de la Universidad de Granada     Open Access  
Chronique d'Egypte     Full-text available via subscription   (Followers: 6)
Church History and Religious Culture     Hybrid Journal   (Followers: 51)
Church History: Studies in Christianity and Culture     Full-text available via subscription   (Followers: 72)
Civil War History     Full-text available via subscription   (Followers: 19)
Cleveland Studies in the History of Art     Full-text available via subscription   (Followers: 2)
CLIO : Revista de Pesquisa Histórica     Open Access  
Clio y Asociados     Open Access  
Clio. Femmes, Genre, Histoire - Articles     Open Access   (Followers: 11)
Cliodynamics     Open Access  
Collections électroniques de l'INHA     Open Access   (Followers: 1)
Collingwood and British Idealism Studies     Full-text available via subscription   (Followers: 1)
Colonial Latin American Review     Hybrid Journal   (Followers: 9)
Comitatus : A Journal of Medieval and Renaissance Studies     Full-text available via subscription   (Followers: 16)
Comparative Legal History     Full-text available via subscription   (Followers: 6)
Comparative Studies of South Asia, Africa and the Middle East     Full-text available via subscription   (Followers: 17)
Comptabilités     Open Access  
Concorso. Arti e lettere     Open Access  
Conservative Judaism     Full-text available via subscription   (Followers: 5)
Conserveries mémorielles     Open Access  
Contemporaneity : Historical Presence in Visual Culture     Open Access   (Followers: 3)
Contemporary Arab Affairs     Hybrid Journal   (Followers: 3)
Contemporary British History     Hybrid Journal   (Followers: 21)
Contemporary French and Francophone Studies     Hybrid Journal   (Followers: 10)
Convivium     Full-text available via subscription  
Crime, Histoire & Sociétés     Open Access   (Followers: 3)
Critical Historical Studies     Full-text available via subscription   (Followers: 4)
Critique: Journal of Socialist Theory     Hybrid Journal   (Followers: 5)
Cromohs : Cyber Review of Modern Historiography     Open Access  
Crossing Borders : An Interdisciplinary Journal of Undergraduate Scholarship     Open Access   (Followers: 1)
Cuadernos de Historia     Open Access   (Followers: 3)
Cuadernos de historia de España     Open Access   (Followers: 3)
Cuadernos de Historia de la Salud Publica     Open Access  
Cuadernos de Historia del Derecho     Open Access   (Followers: 5)
Cuadernos de Historia Moderna     Open Access   (Followers: 2)
Cuadernos de Ilustración y Romanticismo     Open Access  
Cuban Studies     Full-text available via subscription   (Followers: 6)
Cuicuilco     Open Access   (Followers: 1)
Cultura Histórica & Patrimônio     Open Access  
Cultural and Social History     Full-text available via subscription   (Followers: 36)
Cultural History     Hybrid Journal   (Followers: 18)
Cultural-Historical Psychology     Open Access  
Culturas     Open Access   (Followers: 1)
Cultures & conflits     Open Access   (Followers: 10)
Cultures et conflits     Open Access   (Followers: 1)
Czech-Polish Historical and Pedagogical Journal     Open Access  
Dapim : Studies on the Holocaust     Hybrid Journal   (Followers: 8)
Das Mittelalter     Hybrid Journal   (Followers: 7)
De Arte     Full-text available via subscription   (Followers: 4)
Debatte: Journal of Contemporary Central and Eastern Europe     Hybrid Journal   (Followers: 5)

        1 2 3 4 | Last

Journal Cover British Mycological Society Symposia Series
  [1 followers]  Follow
    
   Full-text available via subscription Subscription journal  (Not entitled to full-text)
   ISSN (Print) 0275-0287
   Published by Elsevier Homepage  [3041 journals]
  • List of contributors
    • Abstract: 2008
      Publication year: 2008
      Source:British Mycological Society Symposia Series, Volume 28



      PubDate: 2012-12-15T09:30:18Z
       
  • Chapter 1 Mycelial networks: Structure and dynamics
    • Abstract: 2008
      Publication year: 2008
      Source:British Mycological Society Symposia Series, Volume 28

      To survive saprotrophic fungi must be able to capture organic resources discontinuously dispersed in space and time. Some basidiomycetes can only achieve this by production of sexual and asexual spores or sclerotia — categorized as ‘resource-unit-restricted’, whereas ‘non-resource-unit-restricted’ basidiomycetes can also spread between organic resources as mycelium. Mycelial distribution and foraging within organic resources and among relatively homogeneously and heterogeneously distributed resources is reviewed. ‘Non-resource-unit-restricted’ Basidiomycota have evolved different patterns of mycelial spread appropriate to discovery of resources of different sizes and distributions. They show remarkable patterns of reallocation of biomass and mineral nutrients on discovery and colonization of new resources. Network architecture is a significant factor in the acquisition and distribution of nutrients, and in survival when parts of the network are destroyed. The costs and benefits of different architectures to large mycelial networks are considered.

      PubDate: 2012-12-15T09:30:18Z
       
  • Chapter 2 Enzymes of saprotrophic basidiomycetes
    • Abstract: 2008
      Publication year: 2008
      Source:British Mycological Society Symposia Series, Volume 28

      Decomposer fungi utilize dead organic matter that is mainly composed of cell wall polysaccharides and other biopolymers. These include cell wall polymers of plant origin (cellulose, hemicelluloses, lignin, pectin), cell wall polysaccharides of fungi (chitin) and nutrient reserve polysaccharide (starch) as well as proteins. Utilization of these polymers necessitates production of extracellular enzymes; the polysaccharide-based biopolymers are usually degraded by hydrolytic enzymes causing endo and/or exocleavage. Lyases and specific oxidases are also produced. Wood-rotting cellulolytic fungi have evolved complex systems of nonenzymatic cellulose cleavage based on the production of reactive oxygen species, but the detailed functioning and relative importance of this decomposition mechanism is still unclear. Lignin decomposition is catalyzed by a set of oxidases and peroxidases with auxiliary enzymes providing hydroxyl radicals, but it also include the provision of enzyme cosubstrates such as organic acids or aryl alcohols. The composition of ligninolytic systems is thus very complex and species-specific. Compared to decomposition of wood, far less is known about basidiomycete species decomposing litter. Some litter-decomposing fungi are apparently physiologically related to ligninolytic wood-rotters but the compositions and regulation of their ligninolytic systems is not so well characterized, and little is known of their enzymology in the natural soil environment. However, it seems clear that litter decomposers are able to degrade lignin as well as cellulose and hemicelluloses and probably also chitin and starch. Their ligninolytic system also plays an important role in the transformation of humic substances including humus formation and mineralization. The main gaps in our current knowledge are in the ecology of enzyme production under natural conditions and in estimating the role of decomposer basidiomycetes in complex biological processes in soils.

      PubDate: 2012-12-15T09:30:18Z
       
  • Chapter 3 Mycelial networks: Nutrient uptake, translocation and role in
           ecosystems
    • Abstract: 2008
      Publication year: 2008
      Source:British Mycological Society Symposia Series, Volume 28

      Sequestration and release of carbon in the decomposer subsystem of the forest floor are key ecosystem functions of saprotrophic basidiomycetes. Both are the result of fungal metabolic processes commonly regulated by nitrogen availability. Saprotrophic basidiomycetes are the primary wood decomposer organisms in N-limited boreal and temperate forests. To predict the ecosystem effects of atmospheric nitrogen deposition in forests, we need better understanding of the fungal adaptive responses that link carbon conversions to nitrogen dynamics. Some Basidiomycota clades have evolved the capacity to develop mass flow nutrient channels-cords-in response to nutrient context. Rapid bidirectional nutrient transport in cords enables these fungi to operate extensive and persistent resource supply networks, and to exploit the spatiotemporally uncoupled carbon and nitrogen resources of the upper soil horizons of the forest floor. Both the initiation of cord development and the velocity, direction and magnitude of amino acid flows within the corded network are regulated in response to the amounts and geometry of its carbon and nitrogen supply. Predictive models of fungal metabolic, physiological and developmental responses to environmental nitrogen, at cell and organism scale, can be realistically parameterized with data from experimentally manipulated saprotrophic mycelia in microcosms and ecosystems. In future, the whole-genome sequence of the basidiomycete cord-forming wood decay fungus Serpula lacrymans will provide a model for -omics technologies to dissect the extracellular and intracellular nutrient responses that underlie the functions of basidiomycete networks in ecosystems.

      PubDate: 2012-12-15T09:30:18Z
       
  • Chapter 4 Ecophysiology: Impact of environment on growth, synthesis of
           compatible solutes and enzyme production
    • Abstract: 2008
      Publication year: 2008
      Source:British Mycological Society Symposia Series, Volume 28

      Basidiomycetes are important components of the decomposer microbial community involved in nutrient cycling and have been exploited successfully in the production of cultivated mushrooms. Environmental factors such as water availability, temperature and pH and their interactions have significant impacts on basidiomycete colonisation and fruiting potential. This chapter examines the effect that temperature, water availability and their interactions have on growth of different temperate and tropical basidiomycetes. Temperature ranges vary widely between temperate and tropical species and profiles for growth are presented. Basidiomycetes are generally more sensitive to matric than solute stress. This has been shown for Trametes species, as well as with Agaricus bisporus and Pleurotus species. The mechanisms of water-stress tolerance have received much attention, especially for cultivated species, where methods for optimising fruiting has been of interest. Sugar alcohols are involved in water-stress tolerance and the role of these in providing a gradient of water movement within mycelium of a range of cultivated and decay species. Basiodiomycetes produce significant amounts of extracellular enzymes to enable them to play such an important role in decomposition processes. Production of cellulases, ligninases and laccases occur over a wide range of temperature and water potentials. At below the wilting point of plants laccases, cellulases and lignin peroxidases are produced in soil. The ability to produce copious amounts of these enzymes and their stability has resulted in their biotechnological exploitation.

      PubDate: 2012-12-15T09:30:18Z
       
  • Chapter 5 Fruit bodies: Their production and development in relation to
           environment
    • Abstract: 2008
      Publication year: 2008
      Source:British Mycological Society Symposia Series, Volume 28

      Sexual reproduction is important because it generates genetic variation, offers an escape from DNA parasites and provides a means to repair DNA damage. Many fungi exhibit particular patterns of sexual fruit body morphogenesis but the characteristics differ between species. However, it is possible to generalise that within developing fruit body tissues, fungal cells embark on a particular course of differentiation in response to the interaction of their intrinsic genetic programme with external physical signals (light, temperature, gravity, humidity), and/or chemical signals from the environment and other regions of the developing structure. Fruit body morphogenesis is affected by carbon and mineral nutrient availability and environmental variables including temperature, water availability, CO2, light and interactions with other fungi and bacteria. Changes in the seasonal pattern of fruiting in the UK can be detected from field records made in the last 50 years, and while not all species behave in the same way, mean first fruiting date is now significantly earlier and mean last fruiting date is now significantly later, which results in an extended fruiting season. Significant numbers of species that previously only fruited in autumn now also fruit in spring. Such analyses show that relatively simple field observations of fungi can detect climate change, and that fungal responses are sufficiently sensitive to react to the climate change that has already occurred by adapting their pattern of development. Unfortunately, though it is possible to deduce the decisive steps in development that are open to influence, the molecular controls that normally regulate those steps remain unknown. Extensive genomic analysis shows that sequences crucial to multicellular development in animals or plants do not occur in fungal genomes, so we are ignorant of the basic control processes of fungal multicellular developmental biology.

      PubDate: 2012-12-15T09:30:18Z
       
  • Chapter 6 Population biology of forest decomposer basidiomycetes
    • Abstract: 2008
      Publication year: 2008
      Source:British Mycological Society Symposia Series, Volume 28

      This chapter covers aspects of fungal individuality, the size and dynamics of individual mycelia and how its integrity is controlled through somatic incompatibility. It also addresses gene flow and dispersal in wood-decay basidiomycetes.

      PubDate: 2012-12-15T09:30:18Z
       
  • Chapter 7 Interactions between saprotrophic fungi
    • Abstract: 2008
      Publication year: 2008
      Source:British Mycological Society Symposia Series, Volume 28

      Fungal competition for resources can be divided into primary and secondary resource capture. With the former resources have not already been colonized, unlike the latter where combat and antagonistic mechanisms are used to obtain and defend territory. Such interactions can be mediated: (1) at a distance; (2) following contact at the hyphal level; or (3) following contact at the mycelial level. Antagonisms at a distance and at the mycelial level are effected by volatile and diffusible chemicals including enzymes, toxins and other antifungal metabolites. At the hyphal level antagonism is via hyphal interference or parasitism, which again is chemically or enzymatically mediated but on a more localized scale. Interactions have largely been studied on artificial media with the attendant problems of interpretation because of large divergence from field conditions, although soil microcosms have provided a valuable tool for interactions between cord-forming fungi; interactions have also been investigated by inoculating pairs of saprotrophs directly into wood in the field. Microcosm and field-based knowledge of interactions is crucial, not least because of the role of interactions in ecosystem functioning, particularly nutrient cycling and release, their effects on decomposition rates and potential as biological control agents.

      PubDate: 2012-12-15T09:30:18Z
       
  • Chapter 8 Interactions between saprotrophic basidiomycetes and bacteria
    • Abstract: 2008
      Publication year: 2008
      Source:British Mycological Society Symposia Series, Volume 28

      Bacteria, play an important role in the functioning of lignocellulose-degrading basidiomycetes. They can have a negative effect on fungal growth and activity as they are potential competitors for low-molecular weight compounds released by extracellular fungal enzymes. There are also some indications of bacterial mycophagy. On the other hand, basidiomycetes may benefit from the presence of bacteria, in particular with respect to nitrogen supply and detoxification of mycotoxic compounds. During degradation of wood by basidiomycetes, the environmental conditions become very selective for bacteria because of rapid and strong acidification, production of reactive oxygen species and the presence of toxic fungal secondary metabolites. The bacteria that survive these conditions must have special properties, but research on this is still in its infancy. A better knowledge of the interactions between saprotrophic basidiomycetes and bacteria is not only important from a basic scientific point of view, but will also open up possibilities for new applications in wood conservation and the discovery of metabolities with medical therapeutic value.

      PubDate: 2012-12-15T09:30:18Z
       
  • Chapter 9 Interactions between basidiomycota and invertebrates
    • Abstract: 2008
      Publication year: 2008
      Source:British Mycological Society Symposia Series, Volume 28

      Basidiomycota are, in most terrestrial habitats, the primary agents of organic matter decomposition. They play a key role in associated ecosystem processes. Inevitably they interact frequently with invertebrates, and these interactions are highly dynamic. They may be direct or indirect, and prove beneficial or detrimental to either or both partners. In this chapter the variety of interactions is explored and the impact of basidiomycetes as a food and habitat resource, and as a predator is assessed. The consequence of fungal-invertebrate interactions on fungal community structure and faunal behaviour is also considered, as are the implications of these effects on nutrient cycling and ecosystem processes such as decomposition and productivity. The sensitivity of the interacting organisms to changes in climate, and general environmental change, with consequential effects on ecosystem activity, is also discussed.

      PubDate: 2012-12-15T09:30:18Z
       
  • Chapter 10 Distribution and function of litter basidiomycetes in
           coniferous forests
    • Abstract: 2008
      Publication year: 2008
      Source:British Mycological Society Symposia Series, Volume 28

      The spatio-temporal distribution of basidiomycetes colonising coniferous litter, and their impact on carbon and nitrogen cycling is reviewed. Afteria brief phase of colonisation by phyllosphere ascomycetes and ephemeral basidiomycetes, litter is colonised by fungi with higher capacity for litter decomposition, such as Mycena species. This change in fungal community composition involves a shift in substrate utilisation from relatively readly available sugars to cellulose. The fungi overcome the nitrogen deficiency experienced during litter colonisation by translocating nitrogen from older parts of the mycelium. To retrieve nitrogen from well-decomposed litter, the fungi presumably use carbohydrates translocated from fresh litter as a co-substrate to attack polyphenol-nitrogen complexes. After a few years of decomposition, the saprotrophic fungal community is out-competed by mycorrhizal fungi. Their direct access to photo-assimilates is likely to be a major competitive advantage in highly recalcitrant and cellulose-depleted resources. Decomposition is continued by the mycorrhizal fungi, although at a very slow rate. It is not until this phase that net losses of nitrogen from the litter occur, as the mycorrhizal fungi forage for nitrogen to support themselves and their host plants. In low-productivity coniferous forests, saprotrophic fungi, thus, re-cycle litter carbon to the atmosphere, whereas re-cycling of litter nitrogen to growing plants is performed largely by my-corrhizal fungi.

      PubDate: 2012-12-15T09:30:18Z
       
  • Chapter 11 Distribution and role of mat-forming saprobic basidiomycetes in
           a tropical forest
    • Abstract: 2008
      Publication year: 2008
      Source:British Mycological Society Symposia Series, Volume 28

      This chapter provides a brief synopsis of previous studies on the ecology of agaric decomposers that form litter ‘mats’ in tropical forests, augmented by data from temperate forest studies. Description of several experiments in tropical forests of the Luquillo Mountains in Puerto Rico is included. These studies showed higher rates of mass loss in leaves that were decomposed on basidiomycete mycelia (i.e., white-rot) than in the absence of basidiomycetes. The density of litter mats that were bound by basidiomycetes decreased with elevation and increased with slope. Addition of nitrogen inhibited mycelial growth. Capture of new litter by basidiomycetes was inhibited by nitrogen at high elevation. Litter-binding basidiomycetes exhibited differential responses to moisture, associated with full and partial shades. Micromphale bevipes was the only species that grew better in partial than in full shade. Marasmius crinis-equi had the highest rates of new attachments to litter in both full and partial shade, and was considered most suitable for use in restoration of steep road cuts and landslides to reduce erosion.

      PubDate: 2012-12-15T09:30:18Z
       
  • Chapter 12 Basidiomycete community development in temperate angiosperm
           wood
    • Abstract: 2008
      Publication year: 2008
      Source:British Mycological Society Symposia Series, Volume 28

      The wide variety of dead wood habitats supports a wide variety of specialized fungi, which globally may exceed 100,000 species. Of these the majority of known taxa are Basidiomycota. They exhibit a wide variety of strategies to gain and hold territory within wood, defined by their mode of dispersal, establishment, competitive ability and adaptation to disturbance and stress factors. Many habitat factors affect community composition and development, both exogenous, e.g. microclimatic regime, and endogenous, e.g. interspecific interactions. Initial microenvironmental, factors—at one extreme high stress and at the other extreme absence of abiotic stress—are major determinants of the communities that establish. Following initial establishment, community development is influenced by four main driving forces: stress aggravation (worsening of abiotic environmental conditions), stress alleviation (improvement in abiotic conditions), disturbance and combat (interspecific competition for space rather than directly for nutrients). The ecological strategies adopted by wood decay Basidiomycota, habitat factors influencing community development and community development pathways are discussed in relation to angiosperm wood.

      PubDate: 2012-12-15T09:30:18Z
       
  • Chapter 13 Wood-decay basidiomycetes in boreal forests: Distribution and
           community development
    • Abstract: 2008
      Publication year: 2008
      Source:British Mycological Society Symposia Series, Volume 28

      Dead wood and wood-inhabiting fungi are of key importance for biodiversity in boreal forests, and also for global CO2 dynamics. Of more than 10,000 non-lichenised fungal species in Fennoscandia, over 2,500 are wood inhabiting Anthropogenic influences such as forest harvesting and fire suppression have reduced the availability of dead wood in forests, resulting in many wood-decay fungi being considered threatened. Classic inventory approaches have been complemented by pure culture studies of mycelia and recently by molecular detection methods. Nutrient cycling and interspecific interactions play important parts in the development of fungal communities. Boreal fungal communities are, in general, less diverse and more similar on a global scale compared to communities from the temperate regions.

      PubDate: 2012-12-15T09:30:18Z
       
  • Chapter 14 Distribution patterns of wood-decay basidiomycetes at the
           landscape to global scale
    • Abstract: 2008
      Publication year: 2008
      Source:British Mycological Society Symposia Series, Volume 28

      Distribution patterns of fungi and other organisms are influenced by several factors over various scales in time and space. With their microscopic, often wind-dispersed spores, fungi are potentially able to disperse between continents, and many wood-inhabiting fungi with broad host ranges have been thought to have more or less global distribution patterns. With increased insight in fungal taxonomy outside Europe, and the use of molecular methods and mating experiments, it is becoming increasingly clear that many species, previously thought to have a wide distribution, actually circumscribe several biological taxa, each with a much more restricted distribution. Thus, continental drift, glaciations and other long-term geological and geographical factors have more impact on the current distribution patterns of fungi than believed earlier. At the continental scale, climate and host tree distribution patterns are important factors influencing the distribution of wood-inhabiting species, and climate change is likely to affect the distribution patterns of wood-inhabiting fungi considerably in the coming centuries. In the short time, man has had a strong impact on the abundance and distribution of dead wood habitat types, and this has clearly affected current distribution and frequency of many species. Most importantly, species strictly associated with large decaying logs have decreased in many parts of Europe, while common species associated with coniferous wood have expanded in many regions, due to widespread planting of coniferous trees, where such species are naturally absent or infrequent.

      PubDate: 2012-12-15T09:30:18Z
       
  • Chapter 15 Saprotrophic basidiomycetes in grasslands: Distribution and
           function
    • Abstract: 2008
      Publication year: 2008
      Source:British Mycological Society Symposia Series, Volume 28

      Natural and semi-natural grasslands dominate many terrestrial ecosystems, with succession prevented by herbivore grazing, low rainfall and fire. Inputs to grassland soils are typically low in lignin, often comminuted and in the form of dung with below-ground inputs from roots being important. The several hundred basidiomycete species which are preferentially found in grassland can be placed into four functional groupings: litter decomposers, dung fungi, terricolous species and root endophytes. However, detection of these in the absence of basidiocarps has hampered their study, an exception being the fairy ring-forming species. It is clear that basidiomycetes contribute to lignocellulose degradation in grassland soil and litter, though it is likely that ascomycetes play a relatively greater part in this process than in woodland systems. Changes in agricultural management have led to the loss of many semi-natural grasslands in Europe and there are concerns abolit losses of several grassland taxa, such as Hygrocybe and Entoloma spp.

      PubDate: 2012-12-15T09:30:18Z
       
  • Chapter 10 Ecology of marine and freshwater basidiomycetes
    • Abstract: 2008
      Publication year: 2008
      Source:British Mycological Society Symposia Series, Volume 28

      Marine and freshwater basidiomycetes are few in number compared to their terrestrial counterparts and colonize a wide range of substrata: sea-grasses, feathers, wood associated with sand, free floating in the sea, but most occur on mangrove wood or timbers submerged in the sea (boats, piling, sea defences), and leaves and twigs in streams and rivers. They are an ecological group and taxonomically diverse (Agariomycotina, Uredinomycotina and Ustilaginomycotina). Most are able to utilize simple carbohydrates, while filamentous species can decompose cellulose, hemicellulose and lignin. Aquatic basidiomycetes are well adapted to their habitats, with reduced basidiomata. Marine species are known only as teleomorphs with basidiospores generally released passively. Freshwater basidiomycetes are primarily known by their anamorphs on decaying leaves, with conidia that are much branched, while their teleomorphs occur on land and on woody substrata.

      PubDate: 2012-12-15T09:30:18Z
       
  • Chapter 17 Conservation: Selection criteria and approaches
    • Abstract: 2008
      Publication year: 2008
      Source:British Mycological Society Symposia Series, Volume 28

      Conservation of fungi faces the challenge of high species diversity, limited knowledge and a general lack of public awareness. In practical conservation the high species diversity makes it necessary to focus on a limited number of indicator species. Indicator species schemes are burdened by shortcomings: some are experience based and flimsy in their definition of indicator goals, whereas others are scientific in their approach, but with disputable results or an irrelevant indicator goal. The IUCN criteria for red-listing organisms are not specifically designed for fungi, and red-listing fungi, that is calculating the risk of their extinction, is complicated by a limited knowledge on population sizes, lifespan and spatial dynamics in fungi. In this chapter both approaches are discussed from an overall perspective, and with respect to two groups of saprotrophic basidiomycetes which are decreasing in Europe—grassland and wood-inhabiting fungi.

      PubDate: 2012-12-15T09:30:18Z
       
  • Colour section
    • Abstract: 2008
      Publication year: 2008
      Source:British Mycological Society Symposia Series, Volume 28



      PubDate: 2012-12-15T09:30:18Z
       
  • Species index
    • Abstract: 2008
      Publication year: 2008
      Source:British Mycological Society Symposia Series, Volume 28



      PubDate: 2012-12-15T09:30:18Z
       
  • Chapter 1 Interactions between Agaricus bisporus and the pathogen
           Verticillium fungicola
    • Abstract: 2008
      Publication year: 2008
      Source:British Mycological Society Symposia Series, Volume 27

      The interaction between Agaricus bisporus and Verticillium fungicola may be the most economically significant interaction between two fungi. Work described in this chapter covers diverse aspects of the biology and molecular interaction of the host and pathogen and has established a robust baseline for future study of a pathogenic system involving two members of the same kingdom. Pathogen variability has been assessed, and specific genotypes important to major mushroom-producing countries have been characterised. This has enabled representative isolates to be identified for use in this study. A wide range of cell-wall-degrading enzymes from V. fungicola have been identified, and principal component analysis showed a complex correlation between enzyme production and symptom expression. It is likely that some, or indeed many of these enzymes play a critical role in the pathogenicity of Verticillium. Although it is generally accepted that A. bisporus has a relatively narrow genetic base, our work, and that of other groups, has shown that variability in host tolerance to infection with V. fungicola exists to a large extent to justify a detailed study to exploit it. We have developed transformation technologies for the mushroom A. bisporus (Challen et al., 2000; Leach et al., 2004; Foster et al., 2004b; Burns et al., 2005, 2006), its pathogen V. fungicola (Amey et al., 2002, 2003) and other pathogenic fungi (Rogers et al., 2004; Gewiss-Mogensen et al., 2006). Recent advances in gene suppression technologies for the host include deployment of anti-sense and RNAi hairpin constructs to down-regulate endogenous A. bisporus genes (Burns, 2004; Heneghan et al., in press). Similarly gene knockout methodology has been established for the pathogen V. fungicola (Amey et al., 2003;Foster et al., 2004a). An extensive range of genetic resources have been established, which include: V. fungicola pathogenicity simulated cDNA library (mushroom cell wall (MCW) agar), numerous A. bisporus fruiting cDNA libraries (macro-arrayed), host (A. bisporus)-pathogen (V. fungicola) lesions infection SSH libraries (forward and reverse subtractions for up- and down-regulated mushroom genes) and macro-arrayed cDNA infection library, genomic DNA libraries for A. bisporus and other homobasidiomycete mushrooms, EST fungal-fungal interaction database; transformation and expression vectors designed specifically for Agaricus and Verticillium, and vectors to expedite cloning of fragments for gene silencing experiments. The resources now in place will enable us to determine, in a systematic manner, the impact of gene expression on the disease phenotype. This work provides platform technologies for alternative methods of disease control, reduced pesticide use and sustainable crop production. Investigations into this model fungal-fungal interaction will also provide information on the research and development of fungal biological control agents of fungal plant pathogens.

      PubDate: 2012-12-15T09:30:18Z
       
  • Chapter 2 Environmental fluxes and fungal interactions: Maintaining a
           competitive edge
    • Abstract: 2008
      Publication year: 2008
      Source:British Mycological Society Symposia Series, Volume 27

      In all ecosystems, fungi inevitably come into contact with each other as they germinate and grow to become established in specific niches. They use different ecological strategies and have different physiological attributes, which enable them to compete against other species in different nutrition-ally diverse niches. The outcome of such interactions and thus community structure is dependent on factors such as carbon utilisation patterns and fluctuating environmental factors. The ability to grow over a wider water-availability range than bacteria or actinomycetes also gives fungi an advantage in dominating certain ecological domains. The ability to produce secondary metabolites, volatiles or a battery of enzymes provides a competitive edge to a specific fungal species to become established and maintain a competitive edge. This chapter examines the way by which fungi are able to maximise their abilities to tolerate environmental stress to enable them to compete effectively and exclude other species during colonisation of different ecosystems.

      PubDate: 2012-12-15T09:30:18Z
       
  • Chapter 3 Intracellular mycoparasites in action: Interactions between
           powdery mildew fungi and Ampelomyces
    • Abstract: 2008
      Publication year: 2008
      Source:British Mycological Society Symposia Series, Volume 27

      Pycnidial fungi of the genus Ampelomyces are widespread intracellular mycoparasites of powdery mildew fungi worldwide. Their pycnidia are produced in hyphae, conidiophores and immature ascomata of their mycohosts. Thus, they suppress both the asexual and the sexual reproduction of the invaded powdery mildew mycelia, and then destroy them completely. Conidia of Ampelomyces are released from the intracellular pycnidia by the rupture of the pycnidial wall; conidia then germinate on the host plant surfaces, penetrate the intact hyphae of powdery mildew mycelia found in their vicinity and invade them internally growing from cell to cell through the septal pores of the mycohost. The early stage of mycoparasitism is apparently biotrophic, but the invaded cytoplasm then begins to die and a necrotrophic interaction results. Toxin production has not been detected in Ampelomyces, so it might act directly by invasion and destruction of the host cytoplasm. Experimental data showed that parasitized powdery mildew colonies can continue their growth, but their sporulation is stopped soon after Ampelomyces penetrated their mycelia. It is concluded that these mycoparasites represent a stress factor in the life cycle of their mycohosts but their role in the natural control of powdery mildew infections requires further investigations.

      PubDate: 2012-12-15T09:30:18Z
       
  • Chapter 4 The population dynamical consequences of density dependence in
           fungal plant pathogens
    • Abstract: 2008
      Publication year: 2008
      Source:British Mycological Society Symposia Series, Volume 27

      Almost all stages of a plant pathogen life cycle are potentially density dependent. At small scales and short time spans appropriate to a single-pathogen individual, density dependence can be extremely strong, mediated both by simple resource use, changes in the host due to defence reactions and signals between fungal individuals. In most cases, the consequences are a rise in reproductive rate as the pathogen becomes rarer, and consequently stabilisation of the population dynamics; however, at very low density reproduction may become inefficient, either because it is co-operative or because heterothallic fungi do not form sexual spores. The consequence will be historically determined distributions. On a medium scale, appropriate for example to several generations of a host plant, the factors already mentioned remain important but specialist natural enemies may also start to affect the dynamics detectably. This could in theory lead to complex (e.g. chaotic) dynamics, but in practice heterogeneity of habitat and host is likely to smooth the extreme relationships and make for more stable, though still very variable, dynamics. On longer temporal and longer spatial scales evolutionary responses by both host and pathogen are likely to become important, producing patterns which ultimately depend on the strength of interactions at smaller scales.

      PubDate: 2012-12-15T09:30:18Z
       
  • Chapter 5 Differences in stress responses between model and pathogenic
           fungi
    • Abstract: 2008
      Publication year: 2008
      Source:British Mycological Society Symposia Series, Volume 27

      The virulence of the human fungal pathogens Candida albicans and Candida glabrata is dependent upon their ability to mount stress responses. This reflects the importance of these responses in protecting these fungal pathogens against host defences. Recent molecular and genomic studies have contributed significantly to our understanding of C. albicans stress responses and how they are regulated. Interestingly, it is now apparent that C. albicans has diverged significantly from the benign model yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe with respect to the nature and regulation of its stress responses. For example, recent studies, from us and others, have revealed that while key regulatory molecules are conserved in C. albicans, their contributions to the regulation of stress responses have diverged. While much less is known about stress responses in C. glabrata, initial findings suggest that the sensitivity and regulation of stress responses in this fungal pathogen also differs from that in S. cerevisiae and S. pombe. In this chapter I will highlight such differences and discuss how pathogenic Candida species may exploit specialised stress responses to protect themselves during disease progression in the human host.

      PubDate: 2012-12-15T09:30:18Z
       
  • Chapter 6 The remarkably diverse pathogenicity effectors of the obligate
           oomycete Hyaloperonospora parasitica
    • Abstract: 2008
      Publication year: 2008
      Source:British Mycological Society Symposia Series, Volume 27

      Oomycete pathogens of plants, such as potato blight, cause massive yield losses every year but they are also proving to be important to our understanding of host defence mechanisms. Hyaloperonospora parasitica (Hpat) causes downy mildew disease of Arabidopsis and has been used in many studies that analyse the genes and signalling mechanisms of the host plant involved in disease resistance. We have cloned two resistance genes, RPP1 and RPP13, from Arabidopsis that specify isolate-specific resistance to Hpat and shown them to have diverse recognition capabilities and high levels of allelic diversity. Recently, we have cloned the matching pathogen genes, ATR1 and ATR13, that trigger the RPP1 and RPP13 specified resistance, respectively. These genes show no homology to other known proteins and reveal amazing levels of allelic diversity. They demonstrate clear evidence of an “arms race” between host immunity and pathogen-effector proteins. Both genes contain a signal peptide followed by an RXLR motif that we predict is involved in targeting the effectors to the host plant cytoplasm as it shares common features with the RXL motif found in malarial parasite effectors. We predict that these pathogen effectors are involved in suppressing host basal or race-specific immune response mechanisms. The advent of the Hpat genome sequence will, therefore, provide new tools with which to unravel the Arabidopsis immune system.

      PubDate: 2012-12-15T09:30:18Z
       
  • Chapter 7 Ace2 and fungal virulence
    • Abstract: 2008
      Publication year: 2008
      Source:British Mycological Society Symposia Series, Volume 27

      The DNA binding protein, Ace2, plays a major role in the control of cell-cycle progression in Saccharomyces cerevisiae, being a principal regulator of the M/G1 transition and cell separation in particular. Ace2 also plays a significant role in effecting virulence, though in completely different ways, in the fungal pathogens Candida albicans and Candida glabrata. Here we will briefly review Ace2 regulation and function in terms of cell-cycle progression, cell separation and fungal virulence.

      PubDate: 2012-12-15T09:30:18Z
       
  • Chapter 8 Integrative analysis of yeast osmoregulation
    • Abstract: 2008
      Publication year: 2008
      Source:British Mycological Society Symposia Series, Volume 27

      Osmoregulation, i.e. the active control of the cellular water balance, encompasses homeostatic mechanisms crucial for life. The osmoregulatory system in the yeast Saccharomyces cerevisiae is particularly well understood, although many details of the regulatory mechanisms still remain to be discovered. Central to yeast osmoregulation is the high osmolarity glycerol (HOG) signalling network, a branched mitogen-activated protein kinase (MAPK) pathway that converges on the MAPK Hog1. Active Hog1 controls numerous cellular processes in the cytosol (cell cycle, translation, ion, water and glycerol transport and central metabolism) as well as the expression of numerous genes. In order to achieve a quantitative understanding and to fit different processes in a temporal order, we have generated a comprehensive mathematical model of yeast osmoregulation in collaboration with theoreticians. Using model simulation and quantitative time-course experimentation, we have analysed mechanisms of feedback control of the HOG pathway. These studies illustrate how a signalling pathway combines rigorous feedback control with maintenance of signalling competence, as required for a system controlling cell homeostasis.

      PubDate: 2012-12-15T09:30:18Z
       
  • Chapter 9 Oxidative stress, fragmentation and cell death during bioreactor
           growth of filamentous fungi
    • Abstract: 2008
      Publication year: 2008
      Source:British Mycological Society Symposia Series, Volume 27

      The filamentous fungi posses a highly developed secretory pathway enabling them to secrete a broad range of extracellular hydrolases into the environment so as to degrade and utilise an array of environmental polymers. This capacity has been exploited industrially for decades for the production of a range of commercially important enzymes. In particular, Aspergillus niger (glucoamylase), Aspergillus oryzae (α-amylase) and Trichoderma reesei (cellulase) are used commercially as production strains and are reported to produce between 20 g l-1 and 40g l-1 of extracellular enzyme in fed-batch fermentations under optimised conditions. During the fed-batch phase, cultures become denser and growth rate decreases. During this phase, cultures come under increasing environmental stress leading to reactive oxygen accumulation, cell death and autolysis. In this study, we examined changes in morphology, cell death and fragmentation during the fed-batch fermentation of industrial production strains of A. niger and T. reesei and demonstrate that cell death and fragmentation proceeds differently in these two strains. Further, we demonstrate that a localised build up of reactive oxygen species (ROS) appears to precede cell death and fragmentation.

      PubDate: 2012-12-15T09:30:18Z
       
  • Chapter 10 Weak organic acid resistance of spoilage yeasts
    • Abstract: 2008
      Publication year: 2008
      Source:British Mycological Society Symposia Series, Volume 27

      Reduced reliance on the use of chemical preservatives is desirable in the light of recent evidence that raises concerns over whether the large-scale consumption of these compounds is completely safe. Resistance of spoilage yeasts to the organic acid preservatives currently approved for use in foods and beverages is often a major factor preventing a lowering of preservative levels. Recent work has unravelled the stress responses whereby Saccharomyces cerevisiae becomes resistant to such acids. Resistance to high acetic acid is achieved by loss of the plasma membrane channel, the Fps1p aquaglyceroporin, which facilitates diffusional entry of this acid into cells. Acetic acid stress activates the Hog1p MAP kinase, whereupon this active Hog1p causes phosphorylation, ubiquitination and delivery of Fps1p via endocytic pathway to the vacuole for degradation. Other carboxylic acid preservatives (propionic, sorbic or benzoic acids) are too large to enter the yeast cell through the Fps1p channel, but being more lipophilic than acetic acid, can enter cells at appreciable rates by passive diffusion across the lipid bilayer. Resistance to these involves the induction of an activity for catalysing active efflux of the preservative anion from the cell. In S. cerevisiae, this is the plasma membrane Pdr12p ABC-transporter, regulated by a transcription factor (War1p). The major role of War1p appears to be the induction of PDR12 gene in cells stressed by these moderately lipophilic acids. Still other mechanisms of weak acid resistance are present in the Zygosaccharomyces, most notably a capacity for oxidative degradation of sorbic and benzoic acids that is absent in S. cerevisiae.

      PubDate: 2012-12-15T09:30:18Z
       
  • Chapter 11 Heavy metal pollution and genetic adaptations in
           ectomycorrhizal fungi
    • Abstract: 2008
      Publication year: 2008
      Source:British Mycological Society Symposia Series, Volume 27

      Heavy metal toxicity is a strong trigger for evolutionary adaptation in terrestrial biota that colonise metalliferous soils. Here, I will focus on the occurrence of metal tolerance in ectomycorrhizal (ECM) fungi, the predominant group of root symbionts of pioneer trees that try to colonise severely polluted sites. A considerable amount of literature exists on metal-tolerant plants, which is in sharp contrast to what we know about the tolerance in the fungal symbiotic partners that associate with these plants on metalpolluted soils. I will deal with the ecological and evolutionary processes that drive plant and fungal communities and populations on metal-contaminated sites. The few examples of true metal tolerance in ECM fungi are described and mechanisms possibly involved in this tolerance are briefly summarised. How true metal tolerance in ECM fungi can affect a host plant is discussed in the final Section.

      PubDate: 2012-12-15T09:30:18Z
       
  • Chapter 12 Lichens and metals
    • Abstract: 2008
      Publication year: 2008
      Source:British Mycological Society Symposia Series, Volume 27

      The ability of macrolichens to accumulate high levels of potentially toxic metals has led to their widespread use as biomonitors of metal deposition and consideration in biogeochemical prospecting. Metal bioavailability and pH influence the composition of lichen assemblages and play a role in metal fixation and retention. Areas traditionally regarded as highly toxic where few, if any, higher plants survive, support abundant lichens, including rare species restricted to such sites. Lichens grow directly on minerals including uranium, copper, lead and arsenic phosphates. Metal oxalates and lichenacid metal complexes, melanin pigments and organic phosphates may help lichens to tolerate high metal concentrations. Phytochelatin (PC) production by lichen photobionts and thiol peptide status in both symbionts are two possible detoxification mechanisms operating at the cellular level in epiphytic macrolichens and a crustose lichen accumulating over 1.3% dry wt. Cu. Other tolerance mechanisms, including metal binding by metallothioneins, are yet to be considered. Lichens dominate 6% of the land's surface, are pioneers of fresh rock outcrops and contribute to soil formation. Understanding metal uptake and retention by lichens is important for environmental monitoring, understanding global biogeochemical cycles, learning how organisms tolerate potentially toxic elements and for conservation.

      PubDate: 2012-12-15T09:30:18Z
       
  • Chapter 13 Responses of mycorrhizal fungi to stress
    • Abstract: 2008
      Publication year: 2008
      Source:British Mycological Society Symposia Series, Volume 27

      Mycorrhizal fungi are exposed to all or many of the environmental stresses that other fungi may experience. These include extremes of temperature and pH, anoxia, water stress, physical fragmentation, toxic metals and other pollutants, as well as anthropogenic stresses arising from applications of fertilisers, lime and wood ash. Fungi can respond to these stresses by altering their morphology, modifying their external environment or adapting their internal metabolism, although the degree of phenotypic plasticity may vary. Since mycorrhizal fungi obtain their carbon from autotrophic host plants, the fungi may also be exposed to stress through changes in carbon allocation from hosts. The refinement and application of molecular identification methods has led to the realisation that the degree of host specificity shown by some mycorrhizal fungi may be higher than assumed in the past. This implies that the availability of compatible roots will influence fungal survival and changes in the species composition of plant communities. Restricting the supply of assimilates from compatible host roots may thus limit the growth of certain fungi. Other types of biotic stress may arise from interactions with competing mycorrhizal symbionts, other fungi, soil animals or bacteria. These different types of stress are reviewed from physiological, ecological and evolutionary perspectives in an attempt to identify potentially fruitful lines of future research.

      PubDate: 2012-12-15T09:30:18Z
       
  • Chapter 14 Regulation of protein synthesis in yeast by oxidative stress
    • Abstract: 2008
      Publication year: 2008
      Source:British Mycological Society Symposia Series, Volume 27

      All organisms must be able to respond to changes in their external environment. With the availability of genome sequences, much attention has focused on analysing the changes in gene expression/transcription profiles during these adaptive responses. The translation of mRNA into protein is a fundamental component of the gene expression pathway. However, relatively little is known regarding the role of translational control mechanisms in response to stress conditions. Cells typically respond to stress conditions by invoking complex regulatory mechanisms including global inhibition of translation. This reduction in protein synthesis may prevent continued gene expression during potentially error-prone conditions as well as allow for the turnover of existing mRNAs and proteins whilst gene expression is reprogrammed to deal with the stress. The initiation phase of translation has long been thought to be the main target of regulation and represents a key control point for eukaryotic gene expression. Recent data have also implicated control at the post-initiation phase of translation in response to oxidants. This chapter reviews recent studies on yeast and how these findings are leading to a better understanding of the role of translational control in eukaryotic gene expression.

      PubDate: 2012-12-15T09:30:18Z
       
  • Chapter 15 Cell differentiation as a response to oxidative stress
    • Abstract: 2008
      Publication year: 2008
      Source:British Mycological Society Symposia Series, Volume 27

      Photosynthetic dioxygen (O2) discharge and accumulation in the atmosphere compelled cells to adapt or to die in the presence of a reactive compound and to protect themselves from it and from the inevitable formation of more reactive oxygen species (ROS). At the same time, by using O2 as final electron acceptor, early heterotrophs could obtain more energy from reduced carbon and attain faster growth. However, fast growing aerobes were made more dependent on the availability of reduced carbon. In the fight for food, microorganisms colonized different niches including other organisms, which they parasitized or ate. With time, life-damaging ROS became signals used by cells to regulate growth and proliferation, cell differentiation and cell death. We have proposed that cell differentiation is a response to oxidative stress. In different eukaryotic microorganisms, the presence of ROS and the induction of antioxidant mechanisms are associated with development. Moreover, the superoxide-producing NADPH-oxidases proved essential for some developmental processes. The small GTPase RAS-1 also regulates the production of ROS and different mutations in the corresponding gene affect cell differentiation. The process of asexual reproduction (conidiation) in Neurospora crassa involves three morphogenetic transitions, each preceded by a hyperoxidant state. An accentuated redox imbalance, the oxidation and degradation of oxidized protein, oxidative inactivation of different enzyme activities, and increased production of ROS characterize the hyperoxidant state. Null mutants in catalase genes show increased levels of development. Strains without superoxide dismutase express a conidiation rhythm, similar to the “band” strain, which contains a semi-dominant ras-1 mutation. Mutation of NADPH-oxidase genes reduced or completely abolished different developmental processes. Together, these results support our view on cell differentiation as a response to oxidative stress.

      PubDate: 2012-12-15T09:30:18Z
       
  • Chapter 16 Signalling and defences against oxidative stress in Candida
           albicans
    • Abstract: 2008
      Publication year: 2008
      Source:British Mycological Society Symposia Series, Volume 27

      Oxidative stress is one the major mechanisms by which immune cells are able to deal with microbial infections. Pathogens have therefore developed a set of antioxidant mechanisms, both non-enzymatic and enzymatic in nature. This process is adaptive and in the human pathogenic fungus Candida albicans different MAP kinase-mediated signal transduction pathways have been shown to play an essential role in transmitting the signal to downstream effectors, in addition to their roles in other processes such as morphogenesis and virulence. The cell integrity pathway, mediated by the Mkcl MAP kinase, is activated in response to a wide range of conditions, including oxidative, saline and cell wall stress. The HOG pathway, mediated by the Hogl MAP kinase, is also activated in response to different stress situations (osmotic and oxidative) and is able to trigger a transcriptional specific response, which is distinguishable from that due to other mediators such as the Yapl-homologue Capl or the Skn7 regulator. Manipulation of the oxidative stress response, either in the host or in the microbe, may therefore be an important therapeutic mechanism to control fungal infections.

      PubDate: 2012-12-15T09:30:18Z
       
  • Chapter 17 Oxidant-specific protein folding during fungal oxidative
           stress: Activation and function of the yaplp transcription factor in
           Saccharomyces cerevisiae
    • Abstract: 2008
      Publication year: 2008
      Source:British Mycological Society Symposia Series, Volume 27

      Fungal cells are eliminated from animal hosts through oxidative stressmediated mechanisms. The ability to tolerate oxidative stress has been correlated with virulence in pathogenic fungi like Candida and Aspergillus species. The yeast Saccharomyces cerevisiae has served as an excellent model system for both fungal oxidative stress tolerance in particular and eukaryotic oxidant detoxification in general. A central determinant of oxidative-stress resistance in S. cerevisiae is the transcriptional activator protein Yaplp. Yaplp is normally found in the cytoplasm in the absence of oxidative stress but rapidly recruits to the nucleus upon challenge by oxidants such as H202 or diamide. Detailed mutagenesis and functional studies have demonstrated that two different cysteine-rich domains (CRDs) present in Yaplp are involved in detecting and responding to changes in the redox potential of the cell. The carboxy-terminal CRD (c-CRD) is sufficient to provide diamide regulation of nuclear localization to a chimeric green fluorescent protein (GFP) reporter fusion and contains an important nuclear export signal of Yaplp. Biochemical analyses have provided evidence that different folding states of Yaplp are found during diamide or H202 exposure. In the context of wild-type Yaplp, a second amino-terminal CRD (n-CRD) is required for normal regulation and function of Yaplp in response to H2O2 induced oxidative stress. Unlike the situation during diamide stress, correct folding of Yaplp in the presence of H2O2 requires the presence of ancillary factors like the glutathione peroxidase Gpx3p and the Yaplp-interacting protein Ybplp. While regulation of the nuclear export of Yaplp is a key modulatory step during both diamide and H2O2 induced oxidative stress, recent experiments have shown that a second feature of the H2O2 folded state of Yaplp is required to assure normal function in the presence of this oxidant. This review will summarize the state of understanding of oxidant-specific folding of Yaplp and the requirement for the folded state of Yaplp that is generated in the presence of H2O2 during the response to this oxidant.

      PubDate: 2012-12-15T09:30:18Z
       
 
 
JournalTOCs
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