Subjects -> EARTH SCIENCES (Total: 771 journals)
    - EARTH SCIENCES (527 journals)
    - GEOLOGY (94 journals)
    - GEOPHYSICS (33 journals)
    - HYDROLOGY (29 journals)
    - OCEANOGRAPHY (88 journals)

OCEANOGRAPHY (88 journals)

Showing 1 - 77 of 77 Journals sorted by number of followers
Deep Sea Research Part II: Topical Studies in Oceanography     Hybrid Journal   (Followers: 29)
Deep Sea Research Part I : Oceanographic Research Papers     Hybrid Journal   (Followers: 23)
Estuaries and Coasts     Hybrid Journal   (Followers: 23)
Limnology and Oceanography     Hybrid Journal   (Followers: 22)
Progress in Oceanography     Hybrid Journal   (Followers: 21)
Journal of Marine Biology & Oceanography     Hybrid Journal   (Followers: 19)
New Zealand Journal of Marine and Freshwater Research     Hybrid Journal   (Followers: 18)
Journal of Physical Oceanography     Hybrid Journal   (Followers: 18)
Frontiers in Marine Science     Open Access   (Followers: 17)
Journal of Marine Sciences     Open Access   (Followers: 17)
Coastal Engineering     Hybrid Journal   (Followers: 15)
Advances in Oceanography and Limnology     Open Access   (Followers: 15)
Journal of Oceanography     Hybrid Journal   (Followers: 14)
Maritime Studies     Open Access   (Followers: 13)
International Journal of Oceanography     Open Access   (Followers: 12)
Advances in Statistical Climatology, Meteorology and Oceanography     Open Access   (Followers: 11)
Atmospheric and Oceanic Science Letters     Open Access   (Followers: 10)
Bulletin of Marine Science     Full-text available via subscription   (Followers: 9)
Fisheries Oceanography     Hybrid Journal   (Followers: 8)
Journal of Oceanography and Marine Science     Open Access   (Followers: 7)
Open Journal of Marine Science     Open Access   (Followers: 6)
Limnology and Oceanography: Methods     Hybrid Journal   (Followers: 6)
Journal of Operational Oceanography     Hybrid Journal   (Followers: 6)
Physical Oceanography     Hybrid Journal   (Followers: 6)
Paleoceanography and Paleoclimatology     Full-text available via subscription   (Followers: 5)
Marine Science     Open Access   (Followers: 5)
Limnology and Oceanography: Fluids and Environments     Full-text available via subscription   (Followers: 5)
Ocean Yearbook Online     Hybrid Journal   (Followers: 4)
Journal of Oceanology and Limnology     Hybrid Journal   (Followers: 4)
Limnology and Oceanography Letters     Open Access   (Followers: 4)
Journal of Marine Science and Engineering     Open Access   (Followers: 4)
African Journal of Marine Science     Hybrid Journal   (Followers: 4)
Oceanology     Hybrid Journal   (Followers: 3)
Journal of Aquatic Sciences     Full-text available via subscription   (Followers: 3)
Limnology and Oceanography e-Lectures     Open Access   (Followers: 3)
Journal of Coastal Development     Open Access   (Followers: 3)
Ciencias Marinas     Open Access   (Followers: 3)
Journal of Marine Science and Application     Hybrid Journal   (Followers: 3)
Journal of Ocean Engineering and Marine Energy     Hybrid Journal   (Followers: 3)
Tropical Oceanography     Open Access   (Followers: 2)
Indian Journal of Geo-Marine Sciences     Open Access   (Followers: 2)
Mediterranean Marine Science     Open Access   (Followers: 2)
Regional Studies in Marine Science     Hybrid Journal   (Followers: 2)
Annals of Marine Science     Open Access   (Followers: 2)
Limnology and Oceanography: Bulletin     Hybrid Journal   (Followers: 2)
Annals of Limnology and Oceanography     Open Access   (Followers: 2)
Development and Applications of Oceanic Engineering     Open Access   (Followers: 2)
Journal of Ocean Engineering and Technology     Open Access   (Followers: 1)
Ocean Life     Open Access   (Followers: 1)
Marine Systems & Ocean Technology     Hybrid Journal   (Followers: 1)
Journal of Ocean University of China (English Edition)     Hybrid Journal   (Followers: 1)
Marine Life Science & Technology     Hybrid Journal   (Followers: 1)
Journal of Ocean Engineering and Science     Open Access   (Followers: 1)
Coastal Engineering Proceedings : Proceedings of the International Conference on Coastal Engineering     Open Access   (Followers: 1)
Marine Technology Society Journal     Full-text available via subscription   (Followers: 1)
Scientia Marina     Open Access   (Followers: 1)
Western Indian Ocean Journal of Marine Science     Open Access   (Followers: 1)
Asian Journal of Fisheries and Aquatic Research     Open Access  
Thalassas : An International Journal of Marine Sciences     Hybrid Journal  
Oceans     Open Access  
Aquatic Research     Open Access  
Jurnal Kelautan Tropis     Open Access  
Acta Aquatica : Aquatic Sciences Journal     Open Access  
Depik Jurnal Ilmu-Ilmu Perairan, Pesisir dan Perikanan     Open Access  
Journal of Agricultural and Marine Sciences     Open Access  
Turkish Journal of Maritime and Marine Sciences     Open Access  
Arquivos de Ciências do Mar     Open Access  
Scientific Drilling     Open Access  
Jurnal Kelautan : Indonesian Journal of Marine Science and Technology     Open Access  
Oceanologia     Open Access  
Revista de Gestão Costeira Integrada     Open Access  
Revista Ciencias Marinas y Costeras     Open Access  
Egyptian Journal of Aquatic Research     Open Access  
China Ocean Engineering     Hybrid Journal  
Revista de Biología Marina y Oceanografía     Open Access  
Latin American Journal of Aquatic Research     Open Access  
Acta Oceanologica Sinica     Hybrid Journal  
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Marine Life Science & Technology
Number of Followers: 1  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Online) 2662-1746
Published by Springer-Verlag Homepage  [2467 journals]
  • Ultrastructure of Diophrys appendiculata and new systematic consideration
           of the euplotid family Uronychiidae (Protista, Ciliophora)

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      Abstract: Abstract The ultrastructure of ciliates carries important cytological, taxonomical, and evolutionary signals for these single-celled eukaryotic organisms. However, little ultrastructural data have been accumulated for most ciliate groups with systematic problems. In the present work, a well-known marine uronychiid, Diophrys appendiculata, was investigated using electron microscopy and a comparison with, and a discussion considering, phylogenetic analyses were made. The new findings primarily show that: (i) this species lacks the typical alveolar plate, bears cortical ampule-like extrusomes, and has microtubular triads in the dorsal pellicle, and thus exhibits some ultrastructural features in common with most of its previously studied congeners; (ii) each adoral membranelle before the level of frontal cirrus II/2 contains three rows of kinetosomes and each membranelle after the level of frontal cirrus II/2 contains four rows, which might be related with morphogenesis and could be considered as a distinctive character of Diophrys; (iii) some structural details of the buccal field, such as the extra-pellicular fibrils, pellicle, pharyngeal disks and microtubular sheet, were documented. In addition, based on the ultrastructural comparison of representatives, we discuss the differentiation between the subfamilies Diophryinae and Uronychiinae. A hypothetical systematic relationship of members in the order Euplotida based on a wide range of data is also provided.
      PubDate: 2022-11-24
       
  • The micronuclear histone H3 clipping in the unicellular eukaryote
           Tetrahymena thermophila

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      Abstract: Abstract Clipping of the histone H3 N-terminal tail has been implicated in multiple fundamental biological processes for a growing list of eukaryotes. H3 clipping, serving as an irreversible process to permanently remove some post-translational modifications (PTMs), may lead to noticeable changes in chromatin dynamics or gene expression. The eukaryotic model organism Tetrahymena thermophila is among the first few eukaryotes that exhibits H3 clipping activity, wherein the first six amino acids of H3 are cleaved off during vegetative growth. Clipping only occurs in the transcriptionally silent micronucleus of the binucleated T. thermophila, thus offering a unique opportunity to reveal the role of H3 clipping in epigenetic regulation. However, the physiological functions of the truncated H3 and its protease(s) for clipping remain elusive. Here, we review the major findings of H3 clipping in T. thermophila and highlight its association with histone modifications and cell cycle regulation. We also summarize the functions and mechanisms of H3 clipping in other eukaryotes, focusing on the high diversity in terms of protease families and cleavage sites. Finally, we predict several protease candidates in T. thermophila and provide insights for future studies.
      PubDate: 2022-11-24
       
  • Doublets of the unicellular organism Euplotes vannus (Alveolata,
           Ciliophora, Euplotida): the morphogenetic patterns of the ciliary and
           nuclear apparatuses associated with cell division

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      Abstract: Abstract Ciliated protists are one of the most diverse and highly differentiated group among unicellular organisms. Doublets occur in ciliates when two cells fuse into a single individual. Doublets contain two major cellular components (either cell in a doublet) and have traditionally been considered as developmental anomalies. Nevertheless, doublets can divide or even conjugate effectively, which may represent dispersal forms of the life stages. In addition, morphogenesis, as an important process in the life cycle, will provide important insights into the complex differentiation mechanism and various physiological phenomena. However, morphogenetic studies focusing on doublets of ciliates are very limited, which has become an obstacle to understand their complete life history. Here we isolated a doublet strain from the marine species Euplotes vannus (Müller, 1786) Diesing, 1850 and investigated its morphogenetic events during asexual reproduction. Our results indicate that: (1) the opisthe’s oral primordium develops de novo beneath the cortex; (2) the frontoventral and transverse cirral anlagen, cirrus I/1, and marginal anlagen in both dividers develop de novo separately; (3) the dorsal kinety anlagen, the three rightmost ones of which produce three caudal cirri for the proter, occur within the parental structures in the mid-body region; (4) the opisthe acquires two caudal cirri, one from the end of each two rightmost kineties; and (5) there are two macronuclei and one micronucleus in the doublet and they divide amitotically and mitotically, respectively. Finally, we speculate that this special differentiation may be an adaptive form to adverse environments.
      PubDate: 2022-11-24
       
  • New considerations on the phylogeny of Sessilida (Protista: Ciliophora:
           Peritrichia) based on multiple-gene information, with emphasis on colonial
           taxa

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      Abstract: Abstract The subclass Peritrichia, containing two orders Sessilida and Mobilida, is a major group of ciliates with worldwide distribution and high species diversity. Several studies have investigated the phylogeny of peritrichs; however, the evolutionary relationships and classification of some families and genera within the Sessilida remain unclear. In the present study, we isolated and identified 22 peritrich populations representing four families and six genera and obtained 64 rDNA sequences to perform phylogenetic analyses and assess their systematic relationships. Ancestral character reconstruction was also carried out to infer evolutionary routes within the Sessilida. The results indicate: (1) family Vaginicolidae is monophyletic and acquisition of the typical peritrich lorica represents a single evolutionary divergence; (2) core epistylidids evolved from a Zoothamnium-like ancestor and experienced spasmoneme loss during evolution; (3) Campanella clusters with species in the basal clade and shows stable morphological differences with other epistylidids, supporting its assignment to a separate family; (4) the structure of the peristomial lip may be a genus-level character rather than a diagnostic character for discriminating Epistylididae and Operculariidae, thus a redefinition of Operculariidae should be carried out when more species have been investigated; (5) some characters, such as lifestyle (solitary or colonial), spasmoneme and living habit (sessile or free-swimming), evolved repeatedly among sessilids indicating that species with non-contractile stalks or that are free-swimming have multiple evolutionary routes and might derive from any sessilid lineage without a lorica. The close phylogenetic relationships of some morphologically distinct sessilids imply that the diagnoses of some genera and families should be improved.
      PubDate: 2022-11-24
       
  • Hypotrichidium tisiae (Gelei, 1929) Gelei, 1954: a unique hypotrichid
           ciliate having a highly specialized developmental pattern during binary
           division

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      Abstract: Abstract In sharp contrast to their pelagic relatives, the oligotrichs, the overwhelming majority of hypotrich ciliates inhabit the benthos. Only a few species, including those of the genus Hypotrichidium Ilowaisky, 1921, have adapted to a planktonic lifestyle. The ontogenetic mode of the highly differentiated ciliate, Hypotrichidium tisiae (Gelei, 1929) Gelei, 1954, is unknown. In this study, the interphase morphology and the ontogenetic process of this species are investigated. Accordingly, the previously unidentified ciliary pattern of Hypotrichidium is redefined. The main morphogenetic features are as follows: (1) The parental adoral zone of membranelles is inherited completely by the proter and the oral primordium of the opisthe arises in a deep pouch. (2) Five frontoventral cirral anlagen (FVA) are formed: FVA I contributes to the single frontal cirrus, FVA II–IV generate three frontoventral cirral rows, FVA V migrates and forms postoral ventral cirri. (3) All marginal cirral row anlagen develop de novo: each of the two left anlagen forms a single cirral row, while the single right anlage fragments into anterior and posterior parts. (4) Two dorsal kinety anlagen occur de novo, with the right one fragmenting to form kineties 2 and 3. (5) Two long caudal cirral rows are formed at the ends of dorsal kineties 1 and 3. On the basis of the morphogenetic features and phylogenetic analyses, the assignment of Hypotrichidium to the family Spirofilidae Gelei, 1929 within Postoralida is supported. The establishment of separate families for the slender “tubicolous” spirofilids and the highly helical spirofilids is also validated.
      PubDate: 2022-11-24
       
  • A practical reference for studying meiosis in the model ciliate
           Tetrahymena thermophila

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      Abstract: Abstract Meiosis is a critical cell division program that produces haploid gametes for sexual reproduction. Abnormalities in meiosis are often causes of infertility and birth defects (e.g., Down syndrome). Most organisms use a highly specialized zipper-like protein complex, the synaptonemal complex (SC), to guide and stabilize pairing of homologous chromosomes in meiosis. Although the SC is critical for meiosis in many eukaryotes, there are organisms that perform meiosis without a functional SC. However, such SC-less meiosis is poorly characterized. To understand the features of SC-less meiosis and its adaptive significance, the ciliated protozoan Tetrahymena was selected as a model. Meiosis research in Tetrahymena has revealed intriguing aspects of the regulatory programs utilized in its SC-less meiosis, yet additional efforts are needed for obtaining an in-depth comprehension of mechanisms that are associated with the absence of SC. Here, aiming at promoting a wider application of Tetrahymena for meiosis research, we introduce basic concepts and core techniques for studying meiosis in Tetrahymena and then suggest future directions for expanding the current Tetrahymena meiosis research toolbox. These methodologies could be adopted for dissecting meiosis in poorly characterized ciliates that might reveal novel features. Such data will hopefully provide insights into the function of the SC and the evolution of meiosis from a unique perspective.
      PubDate: 2022-11-22
       
  • Group-specific functional patterns of mitochondrion-related organelles
           shed light on their multiple transitions from mitochondria in ciliated
           protists

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      Abstract: Abstract Adaptations of ciliates to hypoxic environments have arisen independently several times. Studies on mitochondrion-related organelle (MRO) metabolisms from distinct anaerobic ciliate groups provide evidence for understanding the transitions from mitochondria to MROs within eukaryotes. To deepen our knowledge about the evolutionary patterns of ciliate anaerobiosis, mass-culture and single-cell transcriptomes of two anaerobic species, Metopus laminarius (class Armophorea) and Plagiopyla cf. narasimhamurtii (class Plagiopylea), were sequenced and their MRO metabolic maps were compared. In addition, we carried out comparisons using publicly available predicted MRO proteomes from other ciliate classes (i.e., Armophorea, Litostomatea, Muranotrichea, Oligohymenophorea, Parablepharismea and Plagiopylea). We found that single-cell transcriptomes were similarly comparable to their mass-culture counterparts in predicting MRO metabolic pathways of ciliates. The patterns of the components of the MRO metabolic pathways might be divergent among anaerobic ciliates, even among closely related species. Notably, our findings indicate the existence of group-specific functional relics of electron transport chains (ETCs). Detailed group-specific ETC functional patterns are as follows: full oxidative phosphorylation in Oligohymenophorea and Muranotrichea; only electron-transfer machinery in Armophorea; either of these functional types in Parablepharismea; and ETC functional absence in Litostomatea and Plagiopylea. These findings suggest that adaptation of ciliates to anaerobic conditions is group-specific and has occurred multiple times. Our results also show the potential and the limitations of detecting ciliate MRO proteins using single-cell transcriptomes and improve the understanding of the multiple transitions from mitochondria to MROs within ciliates.
      PubDate: 2022-11-21
       
  • Ontogenesis and systematic position of a new hypotrichous ciliate,
           Chaetospira sinica sp. nov., with an improved diagnosis of the poorly
           defined family Chaetospiridae Jankowski, 1985 (Protozoa, Ciliophora,
           Hypotrichia)

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      Abstract: Abstract Ciliates are unique single-celled organisms that play important roles in ecological, environmental, evolutionary, and ontogenetic research. In the present study, phylogenetic analyses based on 18S rRNA gene sequence data reveal that Chaetospira sinica sp. nov. clusters with Stichotricha aculeata with strong to full support (97% ML, 1.00 BI), but is not closely related to members of Spirofilidae Gelei, 1929 to which Chaetospira and Stichotricha have previously been assigned. Phylogenetic analyses, together with morphological and morphogenetic data from Chaetospira sinica sp. nov., support the validity of family Chaetospiridae Jankowski, 1985. Chaetospira and Stichotricha are here assigned to the family Chaetospiridae, the improved diagnosis of which is as follows: non-dorsomarginalian Hypotrichia with flask-shaped body; oral region extending along narrow anterior neck region; lorica usually present; two ventral and two marginal cirral rows, all distinctly spiraled or obliquely curved; pretransverse and transverse cirri absent. The basic morphogenetic features in C. sinica sp. nov. can be summarized as: (1) the oral primordium for the opisthe develops de novo and the parental adoral zone is completely retained by the proter; (2) all ventral cirral anlagen and marginal anlagen developed intrakinetally; (3) three dorsal kineties anlagen formed intrakinetally in each daughter cell; and (4) macronuclear nodules fuse into a single mass. Exconjugant cells were also isolated and their morphologic and molecular data are provided.
      PubDate: 2022-11-18
       
  • Phylogeny of the anaerobic ciliate genus Sonderia (Protista: Ciliophora:
           Plagiopylea), including the description of three novel species and a brief
           revision of the genus

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      Abstract: Abstract Anaerobic protists in general, and ciliates in particular, are important components of anoxic or hypoxic environments, however, their diversity remains underestimated. Sonderia is a poorly studied genus that is distributed worldwide and is commonly found in anaerobic environments. In the present study, the taxonomy and phylogeny of three new species, namely Sonderia aposinuata sp. nov., Sonderia paramacrochilus sp. nov. and Sonderia steini sp. nov., collected from China, were investigated based on microscopic observations and SSU rRNA gene sequencing methods. Sonderia aposinuata sp. nov. is diagnosed mainly by having a relatively large body size, a crescent-shaped oral opening, numerous slender extrusomes, one suture on the ventral side and two on the dorsal side, and a buccal cavity that occupies the anterior third of the cell. Sonderia paramacrochilus sp. nov. closely resembles S. macrochilus but differs mainly by its oral opening being located closer to the anterior cell margin and its spindle-shaped extrusomes. Sonderia steini sp. nov. is a freshwater species that can be recognized by its shallow buccal cavity, sparsely distributed rod-shaped extrusomes, and having 68–79 monokinetidal somatic kineties that form sutures on both sides of the body. Phylogenetic analyses based on small subunit ribosomal RNA (SSU rRNA) gene sequence data support the monophyly of the family Sonderiidae, however, Sonderia is paraphyletic. The genus Sonderia is briefly revised and a key to the identification of species belonging to this genus is supplied.
      PubDate: 2022-11-01
       
  • Biodiversity of freshwater ciliates (Protista, Ciliophora) in the Lake
           Weishan Wetland, China: the state of the art

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      Abstract: Abstract Ciliates are core components of the structure of and function of aquatic microbial food webs. They play an essential role in the energy flow and material circulation within aquatic ecosystems. However, studies on the taxonomy and biodiversity of freshwater ciliates, especially those in wetlands in China are limited. To address this issue, a project to investigate the freshwater ciliates of the Lake Weishan Wetland, Shandong Province, commenced in 2019. Here, we summarize our findings to date on the diversity of ciliates. A total of 187 ciliate species have been found, 94 of which are identified to species-level, 87 to genus-level, and six to family-level. These species show a high morphological diversity and represent five classes, i.e., Heterotrichea, Litostomatea, Prostomatea, Oligohymenophorea, and Spirotrichea. The largest number of species documented are oligohymenophoreans. A comprehensive database of these ciliates, including morphological data, gene sequences, microscope slide specimens and a DNA bank, has been established. In the present study, we provide an annotated checklist of retrieved ciliates as well as information on the sequences of published species. Most of these species are recorded in China for the first time and more than 20% are tentatively identified as new to science. Additionally, an investigation of environmental DNA revealed that the ciliate species diversity in Lake Weishan Wetland is higher than previously supposed.
      PubDate: 2022-11-01
       
  • The widely reported but poorly studied ciliate family Folliculinidae
           (Protozoa, Ciliophora, Heterotrichea): a revision with notes on its
           taxonomy, morphology and phylogenetic relationships

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      Abstract: Abstract Ciliates of the heterotrich family Folliculinidae are widespread in various habitats and are distinguished by their transparent loricae of various shapes, conspicuous peristomial lobes, and dimorphic life cycles. They usually attach firmly to the surface of substrates, feed on bacteria and microalgae, and play a significant role in energy flow and material cycling in the microbial food web. However, little is known regarding their biodiversity and systematics. In this work, we establish the terminology of the family Folliculinidae and select six crucial features for genus recognition. Based on previous studies, we revise the classification of Folliculinidae, supply improved diagnoses for each of the 33 folliculinid genera, and provide a key to their identification. Moreover, phylogenetic analyses based on small subunit ribosomal DNA (SSU rDNA) sequences revealed that the family is monophyletic and comprises two subclades (subclades I II) which can be identified by the flexibility of their peristomial lobes and the sculpturing of their necks. Furthermore, we investigate the evolutionary relationships of folliculinids using the six chosen generic features.
      PubDate: 2022-11-01
       
  • Integrative studies on three new freshwater Amphileptus species
           (Ciliophora, Pleurostomatida) discovered in northern China

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      Abstract: Abstract The morphology and molecular phylogeny of freshwater pleurostomatid ciliates are insufficiently explored. In the present study, we investigated three new Amphileptus species discovered in Lake Weishan and its vicinity, northern China, using standard alpha-taxonomic methods. Amphileptus paracarchesii sp. nov. is characterized by a lateral fossa (groove) in the posterior body portion, four macronuclear nodules, contractile vacuoles distributed along the dorsal margin, and 4–6 left and 44–50 right somatic kineties. Amphileptus pilosus sp. nov. differs from congeners by having 4–14 macronuclear nodules, numerous contractile vacuoles scattered throughout the cytoplasm, and 22–31 left and 35–42 right somatic kineties. Amphileptus orientalis sp. nov. is characterized by two ellipsoidal macronuclear nodules, three ventral contractile vacuoles, and about four left and 31–35 right somatic kineties. Phylogenetic analyses of nuclear small subunit ribosomal DNA (SSU rDNA) sequences indicate that the family Amphileptidae might be monophyletic while the genus Amphileptus is paraphyletic, as Pseudoamphileptus macrostoma robustly groups with Amphileptus sp. Although deep phylogenetic relationships of amphileptids are poorly resolved, multiple well-delimited species groups are recognizable within the genus Amphileptus.
      PubDate: 2022-11-01
       
  • Light history modulates growth and photosynthetic responses of a diatom to
           ocean acidification and UV radiation

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      Abstract: Abstract To examine the synergetic effects of ocean acidification (OA) and light intensity on the photosynthetic performance of marine diatoms, the marine centric diatom Thalassiosira weissflogii was cultured under ambient low CO2 (LC, 390 μatm) and elevated high CO2 (HC, 1000 μatm) levels under low-light (LL, 60 μmol m−2 s−1) or high-light (HL, 220 μmol m−2 s−1) conditions for over 20 generations. HL stimulated the growth rate by 128 and 99% but decreased cell size by 9 and 7% under LC and HC conditions, respectively. However, HC did not change the growth rate under LL but decreased it by 9% under HL. LL combined with HC decreased both maximum quantum yield (FV/FM) and effective quantum yield (ΦPSII), measured under either low or high actinic light. When exposed to UV radiation (UVR), LL-grown cells were more prone to UVA exposure, with higher UVA and UVR inducing inhibition of ΦPSII compared with HL-grown cells. Light use efficiency (α) and maximum relative electron transport rate (rETRmax) were inhibited more in the HC-grown cells when UVR (UVA and UVB) was present, particularly under LL. Our results indicate that the growth light history influences the cell growth and photosynthetic responses to OA and UVR.
      PubDate: 2022-09-12
      DOI: 10.1007/s42995-022-00138-x
       
  • Timing and characteristics of nuclear events during conjugation and
           genomic exclusion in Paramecium multimicronucleatum

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      Abstract: Abstract Ciliated protists are ideal material for studying the origin and evolution of sex, because of their nuclear dimorphism (containing both germline micronucleus and somatic macronucleus in the same cytoplasm), special sexual processes (conjugation and autogamy), and high diversity of mating-type systems. However, the study of sexual process is limited to only a few species, due to the difficulties in inducing or observing conjugation. In the present study, we investigate the conjugation process in Paramecium multimicronucleatum: (1) of the three prezygotic divisions, all micronuclei undergo the first two divisions (meiosis I, II), while a variable number of nuclei undergo the third division (mitosis); (2) the synkaryon divides three times after fertilization, giving rise to eight products that differentiate into four macronuclear anlagen and four micronuclei; (3) cells restore the vegetative stage after two successive cell fissions during which the macronuclear anlagen are distributed into daughter cells without division, while micronuclei divide mitotically; (4) the parental macronucleus begins to fragment following the first meiotic division and finally degenerates completely; (5) the entire process takes about 110 h, of which about 85 h are required for macronuclear development. In addition, we describe for the first time the process of genomic exclusion occurring between amicronucleate and micronucleate cells of P. multimicronucleatum, during which the micronucleate cell contributes a pronucleus to the amicronucleate cell, resulting in both exconjugants being homozygotes. These results provide new insights into the diversity of sexual processes and lay an important cytological basis for future in-depth studies of mating systems in ciliates.
      PubDate: 2022-08-19
      DOI: 10.1007/s42995-022-00137-y
       
  • Cluster of differentiation antigens: essential roles in the identification
           of teleost fish T lymphocytes

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      Abstract: Abstract Cluster of differentiation (CD) antigens are cell surface molecules expressed on leukocytes and other cells associated with the immune system. Antibodies that react with CD antigens are known to be one of the most essential tools for identifying leukocyte subpopulations. T lymphocytes, as an important population of leukocytes, play essential roles in the adaptive immune system. Many of the CD antigens expressed on T lymphocytes are used as surface markers for T lymphocyte classification, including CD3, CD4 and CD8 molecules. In this review, we summarize the recent advances in the identification of CD molecules on T lymphocytes in teleosts, with emphasis on the functions of CD markers in the classification of T lymphocyte subsets. We notice that genes encoding CD3, co-receptors CD4 and CD8 have been cloned in several fish species and antibodies have been developed to study protein expression in morphological and functional contexts. T lymphocytes can be divided into CD4+ and CD8+ cells discriminated by the expression of CD4 and CD8 molecules in teleost, which are functionally similar to mammalian helper T cells (Th) and cytotoxic T cells (Tc), respectively. Further studies are still needed on the particular characteristics of teleost T cell repertoires and adaptive responses, and results will facilitate the health management and development of vaccines for fish.
      PubDate: 2022-08-19
      DOI: 10.1007/s42995-022-00136-z
       
  • Solutions: how adaptive changes in cellular fluids enable marine life to
           cope with abiotic stressors

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      Abstract: Abstract The seas confront organisms with a suite of abiotic stressors that pose challenges for physiological activity. Variations in temperature, hydrostatic pressure, and salinity have potential to disrupt structures, and functions of all molecular systems on which life depends. During evolution, sequences of nucleic acids and proteins are adaptively modified to “fit” these macromolecules for function under the particular abiotic conditions of the habitat. Complementing these macromolecular adaptations are alterations in compositions of solutions that bathe macromolecules and affect stabilities of their higher order structures. A primary result of these “micromolecular” adaptations is preservation of optimal balances between conformational rigidity and flexibility of macromolecules. Micromolecular adaptations involve several families of organic osmolytes, with varying effects on macromolecular stability. A given type of osmolyte generally has similar effects on DNA, RNA, proteins and membranes; thus, adaptive regulation of cellular osmolyte pools has a global effect on macromolecules. These effects are mediated largely through influences of osmolytes and macromolecules on water structure and activity. Acclimatory micromolecular responses are often critical in enabling organisms to cope with environmental changes during their lifetimes, for example, during vertical migration in the water column. A species’ breadth of environmental tolerance may depend on how effectively it can vary the osmolyte composition of its cellular fluids in the face of stress. Micromolecular adaptations remain an under-appreciated aspect of evolution and acclimatization. Further study can lead to a better understanding of determinants of environmental tolerance ranges and to biotechnological advances in designing improved stabilizers for biological materials.
      PubDate: 2022-08-16
      DOI: 10.1007/s42995-022-00140-3
       
  • Chemical and biological diversity of new natural products from marine
           sponges: a review (2009–2018)

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      Abstract: Abstract Marine sponges are productive sources of bioactive secondary metabolites with over 200 new compounds isolated each year, contributing 23% of approved marine drugs so far. This review describes statistical research, structural diversity, and pharmacological activity of sponge derived new natural products from 2009 to 2018. Approximately 2762 new metabolites have been reported from 180 genera of sponges this decade, of which the main structural types are alkaloids and terpenoids, accounting for 50% of the total. More than half of new molecules showed biological activities including cytotoxic, antibacterial, antifungal, antiviral, anti-inflammatory, antioxidant, enzyme inhibition, and antimalarial activities. As summarized in this review, macrolides and peptides had higher proportions of new bioactive compounds in new compounds than other chemical classes. Every chemical class displayed cytotoxicity as the dominant activity. Alkaloids were the major contributors to antibacterial, antifungal, and antioxidant activities while steroids were primarily responsible for pest resistance activity. Alkaloids, terpenoids, and steroids displayed the most diverse biological activities. The statistic research of new compounds by published year, chemical class, sponge taxonomy, and biological activity are presented. Structural novelty and significant bioactivities of some representative compounds are highlighted. Marine sponges are rich sources of novel bioactive compounds and serve as animal hosts for microorganisms, highlighting the undisputed potential of sponges in the marine drugs research and development.
      PubDate: 2022-08-01
      DOI: 10.1007/s42995-022-00132-3
       
  • Making comparable measurements of bacterial respiration and production in
           the subtropical coastal waters

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      Abstract: Abstract Accurate estimates of bacterial carbon metabolic rates are indispensable for understanding the regulation of carbon fluxes in aquatic environments. Here, changes in bacterial growth, production, and cell volume in both pre-filtered and unfiltered seawater during 24 h incubation were monitored. The methodological artifacts during Winkler bacterial respiration (BR) measurements in subtropical Hong Kong coastal waters were assessed. Bacterial abundance increased by 3- and 1.8-fold in the pre-filtered and unfiltered seawater after incubation, respectively. Bacterial production (BP) and cell volume also showed significant enhancement. Compared with the BR measurements obtained by the Winkler method, the instantaneous free-living BR measurements, after correction, decreased by ~ 70%. The time-integrated free-living BR and BP during 24 h incubation in the pre-filtered sample provided an improved estimate of bacterial growth efficiency, which increased by ~ 52% compared to the common estimations using the noncomparable measurements of integrated free-living BR and instantaneous total BP. The overestimation of BR also exaggerated the contribution of bacteria to community respiration, affecting the understanding on the metabolic state of the marine ecosystems. Furthermore, the BR estimates by the Winkler method may be more biased in environments with a higher bacterial growth rate and tightly coupled grazing mortality, as well as in those with higher nutrient concentrations. These results reveal obvious problems associated with the BR methodology and raise a warning for caution when comparing BP and BR, as well as when making estimations of carbon flow through the complex microbial networks in aquatic ecosystems.
      PubDate: 2022-07-11
      DOI: 10.1007/s42995-022-00133-2
       
  • Efficient production of mannosylerythritol lipids by a marine yeast
           Moesziomyces aphidis XM01 and their application as self-assembly
           nanomicelles

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      Abstract: Abstract Mannosylerythritol lipids (MELs) are one of the most promising biosurfactants because of their excellent physicochemical properties, high environmental compatibility, and various biological functions. In this study, a mangrove yeast strain Moesziomyces aphidis XM01 was identified and used for efficient extracellular MEL production. The MEL titer reached 64.5 ± 0.7 g/L at flask level within 7 days with the optimized nitrogen and carbon source of 2.0 g/L NaNO3 and 70 g/L soybean oil. Furthermore, during a 10-L two-stage fed-batch fermentation, the final MEL titer reached 113.6 ± 3.1 g/L within 8 days, with prominent productivity and yield of 14.2 g·L−1·day−1 and 94.6 g/g(glucose and soybean oil). Structural analysis indicated that the produced MELs were mainly MEL-A and its fatty acid profile was composed of only medium-chain fatty acids (C8–C12), especially C10 acids (77.81%). Further applications of this compound were evaluated as one-step self-assembly nanomicelles. The obtained MEL nanomicelles showed good physicochemical stability and antibacterial activity. In addition, using clarithromycin as a model hydrophobic drug, the MEL nanomicelles exhibited high loading capacity and could be used for the controlled and sustained drug release in low-pH environments. Therefore, M. aphidis XM01 is an excellent candidate for efficient MEL production, and the prepared MEL nanomicelles have broad application prospects in the pharmaceutical and cosmetic fields.
      PubDate: 2022-06-27
      DOI: 10.1007/s42995-022-00135-0
       
  • An efficient method for chitin production from crab shells by a natural
           deep eutectic solvent

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      Abstract: Abstract Crab shells are an important feedstock for chitin production. However, their highly compact structure significantly limits their use for the production of chitin under mild conditions. Here, a green and efficient approach using a natural deep eutectic solvent (NADES) to produce chitin from crab shells was developed. Its effectiveness in isolating chitin was investigated. The results showed that most proteins and minerals were removed from crab shells and the relative crystallinity of the isolated chitin reached 76%. The quality of the obtained chitin was comparable to chitin isolated by the acid–alkali method. This is the first report on a green method for efficient chitin production from crab shells. This study is expected to open new avenues for green and efficient production of chitin from crab shells.
      PubDate: 2022-04-19
      DOI: 10.1007/s42995-022-00129-y
       
 
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