A New Species of Bisexual Milnesium (Eutardigrada: Apochela) Having Aberrant Claws from Innhovde, Dronning Maud Land, East Antarctica.

There have been several records in the last 60 years for East Antarctica for Milnesium tardigradum Doyère, 1840 sensu lato, now considered a species complex. During the 56th Japanese Antarctic Research Expedition summer operation (2014-2015), a new tardigrade species in the genus Milnesium Doyère, 1840 was found in an ice-free Innhovde area along Lützow-Holm Bay, Dronning Maud Land, East Antarctica. The new species has aberrant claws with four to seven points on each secondary claw branch, which distinguishes it from other Milnesium species. A male specimen was found in the population and evidence showed that an isolated adult female moulted twice without oviposition. This strongly suggested bisexual reproduction for this population. The new species, Milnesium rastrum sp. nov., is described with its phylogenetic position and a discussion on the reproductive strategies for the harsh environments.

Relationship between Urinary Metabolomic Profiles and Depressive Episode in Antarctica.

Antarctic expeditions have a high risk of participant depression owing to long stays and isolated environments. By quantifying the stress state and changes in biomolecules over time before the onset of depressive symptoms, predictive markers of depression can be explored. Here, we evaluated the psychological changes in 30 participants in the Japanese Antarctic Research Expedition using the Patient Health Questionnaire-9 (PHQ-9). Urinary samples were collected every three months for a year, and comprehensive urinary metabolomic profiles were quantified using liquid chromatography time-of-flight mass spectrometry. Five participants showed major depressive episodes (PHQ-9 ≥ 10) at 12 months. The urinary metabolites between these participants and the 25 unaffected participants were compared at individual metabolite and pathway levels. The individual comparisons showed the most significant differences at 12 months in 14 metabolites, including ornithine and beta-alanine. Data from shorter stays showed less significant differences. In contrast, pathway and enrichment analyses showed the most significant difference at three months and a less significant difference at longer stays. These time transitions of urinary metabolites could help in the development of urinary biomarkers to detect subjects with depressive episodes at an early stage.

The Phylogenetic Position of Branchamphinome (Annelida, Amphinomidae) with a Description of a New Species from the North Pacific Ocean.

A new species of amphinomid polychaete, Branchamphinome kohtsukai sp. nov., is described from Japanese waters, 29-211 m in depth. The species is distinguishable from other congeners by the following features: i) branchiae with four-six filaments in midbody segments; ii) two pairs of eyes not coalescent; iii) the ventral side of the first four chaetigers broadly pigmented. This is the first record of Branchamphinome from the North Pacific Ocean. We provide a phylogenetic tree based on the sequences of four genes (COI, 16S, 18S, 28S) and discuss amphinomids' relationships.

Chasing Waterborne Pathogens in Antarctic Human-Made and Natural Environments, with Special Reference to Legionella spp.

Waterborne pathogenic diseases are public health issues, especially for people staying in remote environments, such as Antarctica. After repeated detection of Legionella by PCR from the shower room of Syowa Station, the Japanese Antarctic research station, we wanted to understand the occurrence of waterborne pathogens, especially Legionella, in the station and their potential sources. In this study, we analyzed water and biofilm samples collected from the water facilities of Syowa Station, as well as water samples from surrounding glacier lakes, by 16S rRNA gene-based amplicon sequencing. For Legionella spp., we further attempted to obtain a detailed community structure by using genus-specific primers. The results showed that potentially pathogenic genera were mostly localized in the station, while Legionella spp., Pseudomonas spp., and Mycobacterium spp. were also widely distributed in lakes. Genus-specific analysis of Legionella spp. within the lake environments confirmed the presence of diverse Legionella amplicon sequence variants (ASVs) that were distinctly different from the Legionella ASVs detected in the station. The majority of the Legionella ASVs inhabiting Antarctic lake habitats were phylogenetically distinct from known Legionella species, whereas the ASVs detected in the human-made station tended to contain ASVs highly similar to well-described mesophilic species with human pathogenicity. These data suggest that unexpected Legionella diversity exists in remote Antarctic cold environments and that environmental differences (e.g., temperature) in and around the station affect the community structure.IMPORTANCE We comprehensively examined the localization of potential waterborne pathogens in the Antarctic human-made and natural aquatic environment with special focus on Legionella spp. Some potential pathogenic genera were detected with low relative abundance in the natural environment, but most detections of these genera occurred in the station. Through detailed community analysis of Legionella spp., we revealed that a variety of Legionella spp. was widely distributed in the Antarctic environment and that they were phylogenetically distinct from the described species. This fact indicates that there are still diverse unknown Legionella spp. in Antarctica, and this genus encompasses a greater variety of species in low-temperature environments than is currently known. In contrast, amplicon sequence variants closely related to known Legionella spp. with reported pathogenicity were almost solely localized in the station, suggesting that human-made environments alter the Legionella community.

A comparative study of wavelength-dependent photoinactivation in photosystem II of drought-tolerant photosynthetic organisms in Antarctica and the potential risks of photoinhibition in the habitat.

Background and Aims: All photosynthetic organisms are faced with photoinhibition, which would lead to death in severe environments. Because light quality and light intensity fluctuate dynamically in natural microenvironments, quantitative and qualitative analysis of photoinhibition is important to clarify how this environmental pressure has impacted ecological behaviour in different organisms. Methods: We evaluated the wavelength dependency of photoinactivation to photosystem II (PSII) of Prasiola crispa (green alga), Umbilicaria decussata (lichen) and Ceratodon purpureus (bryophyte) harvested from East Antarctica. For evaluation, we calculated reaction coefficients, Epis, of PSII photoinactivation against energy dose using a large spectrograph. Daily fluctuation of the rate coefficient of photoinactivation, kpi, was estimated from Epis and ambient light spectra measured during the summer season. Key Results: Wavelength dependency of PSII photoinactivation was different for the three species, although they form colonies in close proximity to each other in Antarctica. The lichen exhibited substantial resistance to photoinactivation at all wavelengths, while the bryophyte showed sensitivity only to UV-B light (<325 nm). On the other hand, the green alga, P. crispa, showed ten times higher Epi to UV-B light than the bryophyte. It was much more sensitive to UV-A (325-400 nm). The risk of photoinhibition fluctuated considerably throughout the day. On the other hand, Epis were reduced dramatically for dehydrated compared with hydrated P. crispa. Conclusions: The deduced rate coefficients of photoinactivation under ambient sunlight suggested that P. crispa needs to pay a greater cost to recover from photodamage than the lichen or the bryophyte in order to keep sufficient photosynthetic activity under the Antarctic habitat. A newly identified drought-induced protection mechanism appears to operate in P. crispa, and it plays a critical role in preventing the oxygen-evolving complex from photoinactivation when the repair cycle is inhibited by dehydration.

The effect of tar spot pathogen on host plant carbon balance and its possible consequences on a tundra ecosystem.

In Arctic tundra, plant pathogens have substantial effects on the growth and survival of hosts, and impacts on the carbon balance at the scale of ecological systems. To understand these effects on carbon dynamics across different scales including plant organ, individual, population and ecosystem, we focused on two primary factors: host productivity reduction and carbon consumption by the pathogen. We measured the effect of the pathogen on photosynthetic and respiratory activity in the host. We also measured respiration and the amount of carbon in the pathogen. We constructed a model based on these two factors, and calculated pathogenic effects on the carbon balance at different organismal and ecological scales. We found that carbon was reduced in infected leaves by 118% compared with healthy leaves; the major factor causing this loss was pathogenic carbon consumption. The carbon balance at the population and ecosystem levels decreased by 35% and 20%, respectively, at an infection rate of 30%. This case study provides the first evidence that a host plant can lose more carbon through pathogenic carbon consumption than through a reduction in productivity. Such a pathogenic effect could greatly change ecosystem carbon cycling without decreasing annual productivity.

Recovery and reproduction of an Antarctic tardigrade retrieved from a moss sample frozen for over 30 years.

Long-term survival has been one of the most studied of the extraordinary physiological characteristics of cryptobiosis in micrometazoans such as nematodes, tardigrades and rotifers. In the available studies of long-term survival of micrometazoans, instances of survival have been the primary observation, and recovery conditions of animals or subsequent reproduction are generally not reported. We therefore documented recovery conditions and reproduction immediately following revival of tardigrades retrieved from a frozen moss sample collected in Antarctica in 1983 and stored at -20 °C for 30.5 years. We recorded recovery of two individuals and development of a separate egg of the Antarctic tardigrade, Acutuncus antarcticus, providing the longest records of survival for tardigrades as animals or eggs. One of the two resuscitated individuals and the hatchling successfully reproduced repeatedly after their recovery from long-term cryptobiosis. This considerable extension of the known length of long-term survival of tardigrades recorded in our study is interpreted as being associated with the minimum oxidative damage likely to have resulted from storage under stable frozen conditions. The long recovery times of the revived tardigrades observed is suggestive of the requirement for repair of damage accrued over 30 years of cryptobiosis. Further more detailed studies will improve understanding of mechanisms and conditions underlying the long-term survival of cryptobiotic organisms.

Ideal osmotic spaces for chlorobionts or cyanobionts are differentially realized by lichenized fungi.

Lichens result from symbioses between a fungus and either a green alga or a cyanobacterium. They are known to exhibit extreme desiccation tolerance. We investigated the mechanism that makes photobionts biologically active under severe desiccation using green algal lichens (chlorolichens), cyanobacterial lichens (cyanolichens), a cephalodia-possessing lichen composed of green algal and cyanobacterial parts within the same thallus, a green algal photobiont, an aerial green alga, and a terrestrial cyanobacterium. The photosynthetic response to dehydration by the cyanolichen was almost the same as that of the terrestrial cyanobacterium but was more sensitive than that of the chlorolichen or the chlorobiont. Different responses to dehydration were closely related to cellular osmolarity; osmolarity was comparable between the cyanolichen and a cyanobacterium as well as between a chlorolichen and a green alga. In the cephalodium-possessing lichen, osmolarity and the effect of dehydration on cephalodia were similar to those exhibited by cyanolichens. The green algal part response was similar to those exhibited by chlorolichens. Through the analysis of cellular osmolarity, it was clearly shown that photobionts retain their original properties as free-living organisms even after lichenization.

Continent-wide risk assessment for the establishment of nonindigenous species in Antarctica.

Invasive alien species are among the primary causes of biodiversity change globally, with the risks thereof broadly understood for most regions of the world. They are similarly thought to be among the most significant conservation threats to Antarctica, especially as climate change proceeds in the region. However, no comprehensive, continent-wide evaluation of the risks to Antarctica posed by such species has been undertaken. Here we do so by sampling, identifying, and mapping the vascular plant propagules carried by all categories of visitors to Antarctica during the International Polar Year's first season (2007-2008) and assessing propagule establishment likelihood based on their identity and origins and on spatial variation in Antarctica's climate. For an evaluation of the situation in 2100, we use modeled climates based on the Intergovernmental Panel on Climate Change's Special Report on Emissions Scenarios Scenario A1B [Nakicenovic N, Swart R, eds (2000) Special Report on Emissions Scenarios: A Special Report of Working Group III of the Intergovernmental Panel on Climate Change (Cambridge University Press, Cambridge, UK)]. Visitors carrying seeds average 9.5 seeds per person, although as vectors, scientists carry greater propagule loads than tourists. Annual tourist numbers (∼33,054) are higher than those of scientists (∼7,085), thus tempering these differences in propagule load. Alien species establishment is currently most likely for the Western Antarctic Peninsula. Recent founder populations of several alien species in this area corroborate these findings. With climate change, risks will grow in the Antarctic Peninsula, Ross Sea, and East Antarctic coastal regions. Our evidence-based assessment demonstrates which parts of Antarctica are at growing risk from alien species that may become invasive and provides the means to mitigate this threat now and into the future as the continent's climate changes.

Microbial community composition of terrestrial habitats in East Antarctica with a focus on microphototrophs.

The Antarctic terrestrial environment harbors a diverse community of microorganisms, which have adapted to the extreme conditions. The aim of this study was to describe the composition of microbial communities in a diverse range of terrestrial environments (various biocrusts and soils, sands from ephemeral wetlands, biofilms, endolithic and hypolithic communities) in East Antarctica using both molecular and morphological approaches. Amplicon sequencing of the 16S rRNA gene revealed the dominance of Chloroflexi, Cyanobacteria and Firmicutes, while sequencing of the 18S rRNA gene showed the prevalence of Alveolata, Chloroplastida, Metazoa, and Rhizaria. This study also provided a comprehensive assessment of the microphototrophic community revealing a diversity of cyanobacteria and eukaryotic microalgae in various Antarctic terrestrial samples. Filamentous cyanobacteria belonging to the orders Oscillatoriales and Pseudanabaenales dominated prokaryotic community, while members of Trebouxiophyceae were the most abundant representatives of eukaryotes. In addition, the co-occurrence analysis showed a prevalence of positive correlations with bacterial taxa frequently co-occurring together.

Complete Genome Sequence of Polynucleobacter sp. Strain TUM22923, Isolated from Antarctic Lake Sediment.

Here, we report the complete genome sequence of Polynucleobacter sp. strain TUM22923, isolated from Antarctic lake sediment. This strain has a genome of 1,860,127 bp, comprising 1,848 protein-coding sequences. These sequence data could contribute to the elucidation of genome streamlining and low-temperature adaptation in members of Polynucleobacter, a cosmopolitan group of ultramicrobacteria.

Whole-Genome Sequences of Three Psychrotolerant Mycolicibacterium sp. Strains Isolated from Antarctic Soil.

We report the whole-genome sequences of three psychrotolerant Mycolicibacterium strains, TUM20983, TUM20984, and TUM20985, isolated from Antarctic soils. Taxonomic analyses indicate that these strains are putative new species. These genome sequences may provide insight into the cold adaptation mechanisms of Mycolicibacterium spp. through future comparative genomic studies.

Measurement of solar UV radiation in Antarctica with collagen sheets.

Collagen sheets were used in a unique evaluation method to examine skin damage caused by ultraviolet (UV) light of short wavelength during a season of the Antarctic ozone hole. The collagen sheets were exposed outdoors for 25 and 50 d, in the spring when the ozone hole was formed and in the ozone-hole-free autumn. Extracts from the exposed collagen sheets were analyzed for total protein and terminal amino acid concentrations as an index of collagen fragmentation. The results show that the amount of extractable collagen and terminal amino acid concentration in the spring exposure were approximately double and five times higher, respectively, when compared with those in the autumn exposure. During the ozone hole occurrence, the terminal amino acid concentration of the extracted collagen was about five times higher when exposure lasted 50 d from mid-September to the end of October compared to when exposure lasted 25 d from mid-September to early October. This result could be attributed to a limited amount of short-wavelength UV radiation reaching the ground surface as a result of the low height of the sun in September, when the ozone hole occurred. In fact, UV radiation measurements taken at Syowa Station indicate that short-wavelength UV radiation in the range 290-295 nm was not detected until approximately 1-2 months after the beginning of the ozone hole occurrence.

Microbiomic Analysis of Bacteria Associated with Rock Tripe Lichens in Continental and Maritime Antarctic Regions.

Increased research attention is being given to bacterial diversity associated with lichens. Rock tripe lichens (Umbilicariaceae) were collected from two distinct Antarctic biological regions, the continental region near the Japanese Antarctic station (Syowa Station) and the maritime Antarctic South Orkney Islands (Signy Island), in order to compare their bacterial floras and potential metabolism. Bulk DNA extracted from the lichen samples was used to amplify the 18S rRNA gene and the V3-V4 region of the 16S rRNA gene, whose amplicons were Sanger- and MiSeq-sequenced, respectively. The fungal and algal partners represented members of the ascomycete genus Umbilicaria and the green algal genus Trebouxia, based on 18S rRNA gene sequences. The V3-V4 sequences were grouped into operational taxonomic units (OTUs), which were assigned to eight bacterial phyla, Acidobacteriota, Actinomyceota, Armatimonadota, Bacteroidota, Cyanobacteria, Deinococcota, Pseudomonadota and the candidate phylum Saccharibacteria (also known as TM7), commonly present in all samples. The OTU floras of the two biological regions were clearly distinct, with regional biomarker genera, such as Mucilaginibacter and Gluconacetobacter, respectively. The OTU-based metabolism analysis predicted higher membrane transport activities in the maritime Antarctic OTUs, probably influenced by the sampling area's warmer maritime climatic setting.

Black spicules from a new interstitial opheliid polychaete Thoracophelia minuta sp. nov. (Annelida: Opheliidae).

The phylum Annelida exhibits high morphological diversity coupled with its extensive ecological diversity, and the process of its evolution has been an attractive research subject for many researchers. Its representatives are also extensively studied in fields of ecology and developmental biology and important in many other biology related disciplines. The study of biomineralisation is one of them. Some annelid groups are well known to form calcified tubes but other forms of biomineralisation are also known. Herein, we report a new interstitial annelid species with black spicules, Thoracophelia minuta sp. nov., from Yoichi, Hokkaido, Japan. Spicules are minute calcium carbonate inclusions found across the body and in this new species, numerous black rod-like inclusions of calcium-rich composition are distributed in the coelomic cavity. The new species can be distinguished from other known species of the genus by these conspicuous spicules, shape of branchiae and body formula. Further, the new species' body size is apparently smaller than its congeners. Based on our molecular phylogenetic analysis using 18S and 28S sequences, we discuss the evolutionary significance of the new species' spicules and also the species' progenetic origin.

Complete Genome and Plasmid Sequences of the Psychrotolerant Aureimonas Strain SA4125, Isolated from Antarctic Moss Vegetation.

The complete genome sequences of Aureimonas sp. strain SA4125 and its native plasmid pSA4125 were determined. The genome sequence comprises 4,968,066 bp, with a GC content of 66.0%, and contains 4,691 coding DNA sequences (CDSs), 3 rRNA operons, and 50 tRNAs. The native plasmid comprises 131,777 bp, with a GC content of 62.3%, and contains 138 CDSs.

Characterization of the First Cultured Psychrotolerant Representative of Legionella from Antarctica Reveals Its Unique Genome Structure.

Culture-independent analysis shows that Legionella spp. inhabit a wide range of low-temperature environments, but to date, no psychrotolerant or psychrophilic strains have been reported. Here, we characterized the first cultivated psychrotolerant representative, designated strain TUM19329T, isolated from an Antarctic lake using a polyphasic approach and comparative genomic analysis. A genome-wide phylogenetic tree indicated that this strain was phylogenetically separate at the species level. Strain TUM19329T shared common physiological traits (e.g., Gram-negative, limited growth on buffered charcoal-yeast extract α-ketoglutarate [BCYEα] agar with l-cysteine requirements) with its relatives, but it also showed psychrotolerant growth properties (e.g., growth at 4°C to 25°C). Moreover, this strain altered its own cellular fatty acid composition to accumulate unsaturated fatty acid at a lower temperature, which may help maintain the cell membrane fluidity. Through comparative genomic analysis, we found that this strain possessed massive mobile genetic elements compared with other species, amounting to up to 17% of the total genes. The majority of the elements were the result of the spread of only a few insertion sequences (ISs), which were spread throughout the genome by a "copy-and-paste" mechanism. Furthermore, we found metabolic genes, such as fatty acid synthesis-related genes, acquired by horizontal gene transfer (HGT). The expansion of ISs and HGT events may play a major role in shaping the phenotype and physiology of this strain. On the basis of the features presented here, we propose a new species-Legionella antarctica sp. nov.-represented by strain TUM19329T (= GTC 22699T = NCTC 14581T). IMPORTANCE This study characterized a unique cultivated representative of the genus Legionella isolated from an Antarctic lake. This psychrotolerant strain had some common properties of known Legionella species but also displayed other characteristics, such as plasticity in fatty acid composition and an enrichment of mobile genes in the genome. These remarkable properties, as well as other factors, may contribute to cold hardiness, and this first cultivated cold-tolerant strain of the genus Legionella may serve as a model bacterium for further studies. It is worth noting that environmentally derived 16S rRNA gene phylotypes closely related to the strain characterized here have been detected from diverse environments outside Antarctica, suggesting a wide distribution of psychrotolerant Legionella bacteria. Our culture- and genome-based findings may accelerate the ongoing studies of the behavior and pathogenicity of Legionella spp., which have been monitored for many years in the context of public health.

Human change and adaptation in Antarctica: Psychological research on Antarctic wintering-over at Syowa station.

An Antarctic wintering-over station is a unique environment, as a small isolated society facing extreme survival margins. Psychological surveys have been done over ten years, including the Baum test, the Positive and Negative Affect Schedule (PANAS), the Coping Orientation to Problems Experienced (COPE), Subjective Health Complaints Inventory (SHC), the Two-Sided Personality Scale (TSPS) and medical consultations in Syowa Station, a Japanese Antarctic station to reveal the mental status of team members. Team members experienced fewer physical health risks in Antarctica than in Japan. Wintering-over team members reinterpreted situations positively and accepted their environment, sought instrumental social support, planned ahead, and used active coping skills and humour to overcome difficulties. They did not act out emotionally or deny problems. Individuals exhibited two types of coping, either stability through maintaining a previous lifestyle or flexible adjustment to a new way of life. Positive affect remained constant during the wintering-over period. In living through a harsh reality, team members drew support from the subjective feelings of an "internal relationship" with home or family in their minds. Thus, an Antarctic wintering-over station is an ideal isolated environment for psychological surveys, which can help understand future space travel and group managements in everyday societies.

Comprehensive analysis of an Antarctic bacterial community with the adaptability of growth at higher temperatures than those in Antarctica.

To investigate the adaptability to higher temperatures of Antarctic microorganisms persisting in low temperature conditions for a long time, Antarctic lake samples were incubated in several selection media at 25 degrees C and 30 degrees C. The microorganisms did not grow at 30 degrees C; however, some of them grew at 25 degrees C, indicating that the bacteria in Antarctic have the ability to grow at a wide range of temperatures. Total DNA was extracted from these microorganisms and amplified using the bacteria-universal primers. The amplified fragments were cloned, and randomly selected 48 clones were sequenced. The sequenced clones showed high similarity to the alpha-subdivision of the Proteobacteria with specific affinity to the genus Agrobacterium, Caulobacter and Brevundimonas, the ss-subdivision of Proteobacteria with specific affinity to the genus Cupriavidus, and Bacillus of the phylum Firmicutes. These results showed the presence of universal genera, suggesting that the bacteria in the Antarctic lake were not specific to this environment.

Restriction of sexual reproduction in the moss Racomitrium lanuginosum along an elevational gradient.

Terrestrial plant populations located at the margins of species' distributions often display reduced sexual reproduction and an increased reliance on asexual reproduction. One hypothesis to explain this phenomenon is that the decline is associated with environmental effects on the energetic costs to produce reproductive organs.In order to clarify the changing processes of sexual reproduction along an elevational gradient, we investigated the sexual reproductive parameters, such as the number of sporophytes and gametangia, in Racomitrium lanuginosum, a dioicous moss found on Mt. Fuji.Matured sporophytes were present only below 3,000 m, and the number of sporophytes per shoot tended to be lower at higher elevation habitats. The numbers of male inflorescences per shoot and antheridia per inflorescence and shoot significantly decreased with increasing elevation. In contrast, the numbers of female inflorescences per shoot and archegonia per inflorescence and shoot varied little across elevations. Synthesis. Our results suggest that the reasons for this limitation are assumed to be limitations in sporophyte development that result in abortion, and the spatial segregation between males and females. Possible reasons for the abortion of sporophytes are the inhibitory effects of low air temperature, a shortened growth period, and winter environmental conditions at higher elevations. Remarkable differences between male and female on various reproductive parameters found in this study are thought to affect the mode of sexual reproduction under the harsh environment. These differences between males and females may be caused by differences in the costs of production and development of gametangia, sensitivity to environmental stressors, and phenological patterns.