New Polyketides from the Antarctic Fungus Pseudogymnoascus sp. HSX2#-11

The species Pseudogymnoascus is known as a psychrophilic pathogenic fungus with a ubiquitous distribution in Antarctica. Meanwhile, the study of its secondary metabolites is infrequent. Systematic research of the metabolites of the fungus Pseudogymnoascus sp. HSX2#-11, guided by the method of molecular networking, led to the isolation of one novel polyketide, pseudophenone A (1), along with six known analogs (2–7). The structure of the new compound was elucidated by extensive spectroscopic investigation and single-crystal X-ray diffraction. Pseudophenone A (1) is a dimer of diphenyl ketone and diphenyl ether, and there is only one analog of 1 to the best of our knowledge. Compounds 1 and 2 exhibited antibacterial activities against a panel of strains. This is the first time to use molecular networking to study the metabolic profiles of Antarctica fungi.     

南极半岛海洋气候区的土壤 I.风化作用

南极海洋性气候区是南极风化与成土作用相对较强的地区。本文在对本区气候特点进行分析的基础上,明确了冻胀风化是本区最主要的物理风化形式,强烈的现代地貌过程对本区风化与成土过程具有显著影响。阐述了本区内化学风化的主要过程、机制与产物,同时指出生物因素在本区的岩石风化与原始土壤形成过程具有重要意义。     

南极布兰斯菲尔德海峡磷虾渔场夏秋季汤氏纽鳃樽食物组成及其影响因素研究

为了研究南极磷虾渔场汤氏纽鳃樽的食物组成及其影响因素,实验基于2020年3—4月在布兰斯菲尔德海峡采集到的汤氏纽鳃樽样本,通过分析肠道内容物确定了其食物组成,并进一步分析了其食性的月间以及生活史阶段间差异.结果发现,汤氏纽鳃樽主要摄食硅藻和浮游动物,还少量摄食纤毛虫、原生动物等,优势饵料为羽状环毛藻;汤氏纽鳃樽的摄食存...     

Enzymatic activities and microbial communities in an Antarctic dry valley soil: Responses to C and N supplementation

The soils of the Antarctic dry valleys are exposed to extremely dry and cold conditions. Nevertheless, they contain small communities of micro-organisms that contribute to the biogeochemical transformations of the bioelements, albeit at slow rates. We have determined the dehydrogenase, β-glucosidase, acid and alkaline phosphatase and arylsulphatase activities and the rates of respiration (CO₂ production) in laboratory assays of soils collected from a field experiment in an Antarctic dry valley. The objective of the field experiment was to test the responses of the soil microbial community to additions of C and N in simple (glucose and NH₄Cl) and complex forms (glycine and lacustrine detritus from the adjacent lake comprising principally cyanobacterial necromass). The soil samples were taken 3 years after the experimental treatments had been applied. In unamended soil, all enzyme activities and respiration were detected indicating that the enzymatic capacity to mineralize organic C, P and S compounds existed in the soil, despite the very low organic matter content. Relative to the control (unamended soil), respiration was significantly increased by all the experimental additions of C and N except the smallest NH₄Cl addition (1 mg N g⁻¹ soil) and the smallest detritus addition (1.5 mg C g⁻¹ soil and 0.13 mg N g⁻¹ soil). The activities of all enzymes except dehydrogenase were increased by C and combined large C (10 mg C g⁻¹ soil) and N additions, but either unchanged or diminished by addition of either N only or N (up to 10 mg N g⁻¹ soil) with only small C (1 mg C g⁻¹ soil) additions in the form of glucose and NH₄Cl. This suggests that in the presence of a large amount of N, the C supply for enzyme biosynthesis was limited. When normalized with respect to soil respiration, only arylsulphatase per unit of respiration showed a significant increase with C and N additions as glucose and NH₄Cl, consistent with S limitation when C and N limitations have been alleviated. Based on the positive responses of enzyme activity, detritus appeared to provide either conditions or resources which led to a larger biological response than a similar amount of C and more N added in the form of defined compounds (glucose, NH₄Cl or glycine). Assessment of the soil microbial community by ester-linked fatty acid (ELFA) analysis provided no evidence of changes in the community structure as a result of the C and N supplementation treatments. Thus the respiration and enzyme activity responses to supplementation occurred in an apparently structurally stable or unresponsive microbial community.     

2012年夏季南奥克尼群岛水域表层海水中典型痕量元素分布研究

根据2012年夏季南奥克尼群岛水域采集的表层水样本,利用原子吸收分光光度法分析了该水域表层水中的铜,铅,锌和铁的含量及分布。结果表明：铜浓度在0.033-0.121mg/L之间,铅浓度在0.414-1.478 mg/L之间,锌浓度在0.008 -0.083 mg/L之间,铁浓度在0.255-0.454 mg/L之间,平均值分别为0.059 mg/L,0.908 mg/L,0.037 mg/L和0.351mg/L。铁与锌含量有着自西向东逐渐增加的趋势。本研究可为建立南极半岛海洋环境信息数据库提供基础数据,为进一步开展南大洋海洋生物地球化学研究奠定良好的基础。     

An integrative insight into the synsacral canal of fossil and extant Antarctic penguins

The lumbosacral-canal system in birds most likely operates as a sense organ involved in the control of balanced walking and perching, but our knowledge of it is superficial. Penguins constitute interesting objects for the study of this system due to their upright walking, but only the Humboldt penguin, Spheniscus humboldti, and some incomplete fossil penguin synsacra have been studied in this respect. Here, we give an integrative comparative insight into the synsacral canal of extant Emperor penguin, Aptenodytes forsteri, Adelie penguin, Pygoscelis adeliae, and Eocene giant Anthropornis and/or Palaeeudyptes Antarctic penguins, using computed tomography imaging and associated data-extraction methodologies, complemented by analytical approaches ranging from geometric morphometrics to modularity, curvature, and wavelet analyses. We document that the variability in the number of synsacro-lumbar vertebrae is evolutionarily conserved, and all studied synsacra possess osteological correlates of the lumbosacral-canal system. We also found that Eocene and extant Antarctic penguins were separable on the basis of the main direction of the shape-related (size-independent) variability within said system, and A. forsteri was unique in the entire studied set in terms of the relative cranial shift of this compound structure. Moreover, we suggest that the evolutionary processes, shaping both the terrestrial posture and gait, were responsible, in extant penguins, for the increased simplicity and stability of the synsacral canal cross-sectional periodic patterns, as well as pave the way for the lumbosacral-canal system modularity characterized by reduced atomization/complexity.     

Molecular identification,morphological characterization and new insights into the ecology of larval Pseudoterranova cattani in fishes from the Argentine coast with its differentiation from the Antarctic species,P. decipiens sp. E (Nematoda: Anisakidae)

Larvae of the genus Pseudoterranova constitute a risk for human health when ingested through raw or undercooked fish. They can provoke pseudoterranovosis in humans, a fish-borne zoonotic disease whose pathogenicity varies with the species involved, making their correct specific identification a necessary step in the knowledge of this zoonosis. Larvae of Pseudoterranova decipiens s.l. have been reported in several fish species from off the Argentine coasts; however, there are no studies dealing with their specific identification in this region. Here, a genetic identification and morphological characterization of larval Pseudoterranova spp. from three fish species sampled from Argentine waters and from Notothenia coriiceps from Antarctic waters was carried out. Larvae were sequenced for their genetic/molecular identification, including the mitochondrial cytochrome c oxidase subunit II (mtDNA cox2), the first (ITS-1) and the second (ITS-2) internal transcribed spacers of the nuclear ribosomal DNA, and compared with all species of the P. decipiens (sensu lato) species complex (sequences available in GenBank). Further, adults of Pseudoterranova spp. from the definitive host, the southern sea lion, Otaria flavescens, from Argentine and Chilean coasts were sequenced at the same genes. The sequences obtained at the ITS-1 and ITS-2 genes from all the larvae examined from fish of Argentine waters, as well as the adult worms, matched 100% the sequences for the species P. cattani. The sequences obtained at mtDNA cox2 gene for Antarctic larvae matched 99% those available in GenBank for the sibling P. decipiens sp. E. Both MP and BI phylogenetic trees strongly supported P. cattani and P. decipiens sp. E as two distinct phylogenetic lineages and depicted the species P. decipiens sp. E as sister taxon to the remaining taxa of the P. decipiens complex. Larval morphometry was similar between specimens of P. cattani from Argentina, but significantly different from those of P. decipiens sp. E, indicating that larval forms can be distinguished based on their morphology. Pseudoterranova cattani is common and abundant in a variety of fish species from Chile, whereas few host species harbour these larvae in Argentina where they show low levels of parasitism. This pattern could arise from a combination of factors, including environmental conditions, density and dietary preferences of definitive hosts and life-cycle pathways of the parasite. Finally, this study revealed that the life-cycle of P. cattani involves mainly demersal and benthic organisms, with a marked preference by large-sized benthophagous fish.     

Terrestrial microarthropods of Victoria Land and Queen Maud Mountains, Antarctica: Implications of climate change

We review aspects of climate change likely to impact upon the Collembola and mites (microarthropods) of Victoria Land and the Queen Maud Mountains (VLQMM) in the Ross Sea Region of Antarctica. Five important aspects of biological and biological-environmental interactions are identified as key for understanding the impact of climate change on VLQMM microarthropods: (1) Water availability and utilization; (2) mean temperature (which will affect development and population processes) and extreme temperatures (which affect persistence); (3) ultraviolet radiation, although we note that the periods of peak UV irradiance and microarthropod activity do not coincide; (4) dispersal within and between habitats; and (5) potential establishment of invasive species from within and without Antarctica. The current evidence for effects of climate change on VLQMM microarthropods is equivocal, and we advocate targeted experimental and monitoring studies. Finally, we highlight several areas of high priority for future research, particularly on the mite fauna for which detailed information is currently lacking. These are: (1) functional ecology (including thermal biology, feeding and nutrition and water relations); (2) distribution, dispersal and colonization processes and (3) population and community ecology.