Authors:M.M. Martorell; L.A.M. Ruberto, P.M. Fernández, L.I.C. De Figueroa, W.P. Mac Cormack Pages: 3 - 12 Abstract: Antarctica is one of the most suitable locations for the bioprospecting of psychrotrophic fungi, which play a key role in the nutrient cycle and organic material mineralization in cold environments. These actions mainly take place via the production of several cold-active extracellular enzymes. The aim of this study was to investigate the diversity of filamentous fungi from King George Island (25 De Mayo Island), Antarctica and their ability to produce extracellular hydrolytic enzymes at low temperatures. A total of 51 fungal isolates were obtained from 31 samples. Twelve genera were identified, with seven among the Ascomycota (Cadophora, Helotiales, Monographella, Oidodendron, Penicillium, Phialocephala, Phialophora, Phoma and Pseudogymnoascus), one Basidiomycota (Irpex) and two Mucoromycota (Mortierella and Mucor). Monographella lycopodina and Mucor zonatus, not previously reported in Antarctica, were identified. Nine isolates could not be identified to genus level and may represent novel species. Most of the studied fungi were psychrotrophic (76.5%). Nevertheless, only five isolates were able to grow at 35°C, 15°C being the optimal growth temperature for 65% of the fungal isolates. Results from enzyme production at low temperature revealed that the Antarctic environment contains metabolically diverse fungi, which represent potential tools for biotechnological applications in cold regions. PubDate: 2019-02-01T00:00:00.000Z DOI: 10.1017/S0954102018000421 Issue No:Vol. 31, No. 1 (2019)
Authors:Paul K. Dayton; John S. Oliver, Simon F. Thrush, Kamille Hammerstrom Pages: 13 - 15 Abstract: Carrion in the form of dead seal pups and algal mats placed on soft bottom habitats at Explorers Cove and Salmon Bay, McMurdo Sound, attract scavenging invertebrates that are driven away by hydrogen sulphide produced by sulphate-reducing bacteria sequestered below a layer of Beggiatoa/Thioploca-like filamentous bacteria. This system is usually found for lipid-rich marine mammal carrion, but also occurred with natural algal mats. PubDate: 2019-02-01T00:00:00.000Z DOI: 10.1017/S0954102018000457 Issue No:Vol. 31, No. 1 (2019)
Authors:Alison C. Cleary; Maria C. Casas, Edward G. Durbin, Jaime Gómez-Gutiérrez Pages: 16 - 22 Abstract: The keystone role of Antarctic krill, Euphausia superba Dana, in Southern Ocean ecosystems, means it is essential to understand the factors controlling their abundance and secondary production. One such factor that remains poorly known is the role of parasites. A recent study of krill diet using DNA analysis of gut contents provided a snapshot of the parasites present within 170 E. superba guts in a small area along the West Antarctic Peninsula. These parasites included Metschnikowia spp. fungi, Haptoglossa sp. peronosporomycetes, Lankesteria and Paralecudina spp. apicomplexa, Stegophorus sp. nematodes, and Pseudocollinia spp. ciliates. Of these parasites, Metschnikowia spp. fungi and Pseudocollinia spp. ciliates had previously been observed in E. superba, as had other genera of apicomplexans, though not Lankesteria and Paralecudina. In contrast, nematodes had previously only been observed in eggs of E. superba, and there are no literature reports of peronosporomycetes in euphausiids. Pseudocollinia spp., parasitoids which obligately kill their host, were the most frequently observed infection, with a prevalence of 12%. The wide range of observed parasites and the relatively high frequency of infections suggest parasites may play a more important role than previously acknowledged in E. superba ecology and population dynamics. PubDate: 2019-02-01T00:00:00.000Z DOI: 10.1017/S0954102018000469 Issue No:Vol. 31, No. 1 (2019)
Authors:Xinghao Yao; Tailin Wang, Huijuan Wang, Hongwei Liu, Shenghao Liu, Qingang Zhao, Kaoshan Chen, Pengying Zhang Pages: 23 - 33 Abstract: Mosses have adapted to the Antarctic environment and are an ideal medium for studying plant resistance to abiotic stress. Chalcone synthase is the first committed enzyme in the flavonoid metabolic pathway, which plays an indispensable role in plant resistance to adversity. In this study, six genes (Pn021, PnCHS088, Pn270, PnCHS444, PnCHS768 and Pn847) were identified in the Antarctic moss Pohlia nutans Lindberg transcriptome by reverse transcription polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends (RACE). Sequence alignment and three-dimensional structure analysis revealed the conserved amino acid residues of the enzymes of the chalcone synthase family, including three catalytic residues (Cys164, His303 and Asn336) and two substrate recognition residues (Phe215 and Phe265). Phylogenetic analysis indicated that PnCHS088, PnCHS444 and PnCHS768 might be chalcone synthase but that Pn021 is more like stilbenecarboxylate synthase. These genes were located at the transition between fungi and advanced plants in the phylogenetic tree. In addition, real-time PCR analysis revealed that the expression profiles of the six P. nutans genes were influenced by diverse abiotic stresses as well as by abscisic acid and methyl jasmonate. The results presented here contribute to the study of the CHS gene family in polar mosses and further reveal the mechanisms underlying the adaptation of mosses to extreme environments. PubDate: 2019-02-01T00:00:00.000Z DOI: 10.1017/S0954102018000470 Issue No:Vol. 31, No. 1 (2019)
Authors:Ilana Wainer; Peter R. Gent Pages: 37 - 51 Abstract: The changes in the Antarctic Circumpolar Current system associated with the Polar, sub-Antarctic and Subtropical Fronts in the Atlantic are examined in a ten-member ensemble using the Community Earth System Model. Results for the ensemble average mean show that the Polar Front at 25°W shifts to the south by 0.8° during 1970–2000 compared to its mean latitude over the period 1050–1950. This shift is significant because it is more than twice the standard deviation of the mean latitude time series during 1050–1950. The shift is caused by a slight southward displacement of the Antarctic Circumpolar Current, which in turn is caused by a southward shift in the latitude of the maximum zonal wind stress. The sub-Antarctic Front also shows a small southward shift after 1970, with a maximum latitudinal displacement of 0.2°. However, this shift is not significant compared to the standard deviation of the time series during 1050–1950. The Subtropical Front does not change its latitude during 1970–2000 compared to 1050–2000 because there is very little change in the wind-stress curl in the subtropics. Differences in temperature and salinity throughout the water column at 25°W reveal that during 1970–2000 there is freshening of Antarctic Intermediate Water, whereas the Circumpolar Deep Water becomes saltier. PubDate: 2019-02-01T00:00:00.000Z DOI: 10.1017/S0954102018000433 Issue No:Vol. 31, No. 1 (2019)
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