Diatom assemblages in the surface water of the Indian Sector of the Antarctic Surface Water in summer of 1999/2000

Abundance and species composition of diatom assemblages in surface water of the Indian Sector of the Antarctic Surface Water of the Southern Ocean were examined using samples gathered during the JARE-41 Cruise of the icebreaker Shirase in the summer of 1999/2000. On the westward leg (Leg 1), abundance of the diatom assemblage was geographically rather uniform, while species composition was different geographically in mosaic manner. Dominant species on Leg 1 were the pennate Pseudo-nitzschia spp. and the centric Dactyliosolen tenuijunctus, Chaetoceros sp. cf. dichaeta and Chaetoceros neglectus. On the eastward leg (Leg 2), abundance and species composition were different east and west of 60°E. The community to the west was large in abundance and dominated by D. tenuijunctus, while that to the east was small and dominated by the pennate Fragilariopsis species. These diatom assemblages were grouped into four clusters on Leg 1 and three on Leg 2. Mosaic distribution of the clusters was again evident on Leg 1, while rather simple east-west difference was the case on Leg 2. These geographical variations seem to be affected by local sea ice dynamics

First-Principles Study of Electric Field Effects on Magnetic Anisotropy in Ultrathin Ferromagnetic TM (TM = Fe, Co) Films on Pt(111) Underlayer

We study the electric field (EF) effects on the magnetic anisotropy in the ultrathin ferromagnetic TM (TM = Fe, Co) films on the Pt(111) underlayer using relativistic first-principles calculations based on the density functional theory with a special attention on the effects of Pt segregation. The magnetic anisotropy energy, MAE, and the spin magnetic moment, Mspin, of the Pt/TM/Pt(111) and BeO/Pt/TM/Pt(111) systems as well as those of the TM/Pt(111) and BeO/TM/Pt(111) systems are calculated in the absence of or under the EF. It is found that the MAE and its EF dependence of the BeO/Pt/TM/Pt(111) systems, especially those of the BeO/Pt/Co/Pt(111) system, are considerably large. The sign of the EF dependence is such that the MAE and Mspin are increased (decreased) when the EF increases (decreases) the number of electrons in the system. We attribute this unique behavior to the formation of the hybridized majority-spin states originated in the O 2pz, Pt 5d3z2−r2, and TM 3d orbitals of the interfacial atoms

Controlling processes of pCO2 under coastal fast ice around Syowa Station during austral summer; implication for high productive "stealth polynya"

第2回極域科学シンポジウム　共通セッション「海氷圏の生物地球化学」 11月16日（水） 統計数理研究所 3階セミナー

Integrative Annotation of 21,037 Human Genes Validated by Full-Length cDNA Clones

The human genome sequence defines our inherent biological potential; the realization of the biology encoded therein requires knowledge of the function of each gene. Currently, our knowledge in this area is still limited. Several lines of investigation have been used to elucidate the structure and function of the genes in the human genome. Even so, gene prediction remains a difficult task, as the varieties of transcripts of a gene may vary to a great extent. We thus performed an exhaustive integrative characterization of 41,118 full-length cDNAs that capture the gene transcripts as complete functional cassettes, providing an unequivocal report of structural and functional diversity at the gene level. Our international collaboration has validated 21,037 human gene candidates by analysis of high-quality full-length cDNA clones through curation using unified criteria. This led to the identification of 5,155 new gene candidates. It also manifested the most reliable way to control the quality of the cDNA clones. We have developed a human gene database, called the H-Invitational Database (H-InvDB; http://www.h-invitational.jp/). It provides the following: integrative annotation of human genes, description of gene structures, details of novel alternative splicing isoforms, non-protein-coding RNAs, functional domains, subcellular localizations, metabolic pathways, predictions of protein three-dimensional structure, mapping of known single nucleotide polymorphisms (SNPs), identification of polymorphic microsatellite repeats within human genes, and comparative results with mouse full-length cDNAs. The H-InvDB analysis has shown that up to 4% of the human genome sequence (National Center for Biotechnology Information build 34 assembly) may contain misassembled or missing regions. We found that 6.5% of the human gene candidates (1,377 loci) did not have a good protein-coding open reading frame, of which 296 loci are strong candidates for non-protein-coding RNA genes. In addition, among 72,027 uniquely mapped SNPs and insertions/deletions localized within human genes, 13,215 nonsynonymous SNPs, 315 nonsense SNPs, and 452 indels occurred in coding regions. Together with 25 polymorphic microsatellite repeats present in coding regions, they may alter protein structure, causing phenotypic effects or resulting in disease. The H-InvDB platform represents a substantial contribution to resources needed for the exploration of human biology and pathology

Surface chlorophyll a distribution in marginal ice zone in Antarctica, 1984/85

Chlorophyll α concentrations of surface layer were measured at 108 stations in the Antarctic waters south of 63°S including the pack ice and the fast ice regions along the course of the SHIRASE during the 1984-85 austral summer. High chlorophyll α concentration was observed in the pack ice and the fast ice regions between late December and early January. This high value seems to be correlated with the release of so-called ice algae which proliferated at the bottom part of sea ice. After the disappearance of the sea ice, chlorophyll α concentration in the open water decreased abruptly and became low. After passing through a period of two or three months, the high concentration of chlorophyll α was observed again within Lutzow-Holm Bay and Breid Bay. The growth of the planktonic algae seems to occur in these regions during the austral summer

Surface phytoplankton chlorophyll distribution continuously observed in the JARE-26 cruise (1984/85) to Syowa Station, Antarctica (SIBEX II)

A continuous measuring-recording system of surface chlorophyll α, which is equipped with a personal computer, was used in the 26th Japanese Antarctic Research Expedition (JARE-26) cruise of icebreaker SHIRASE to Syowa Station, Antarctica, in 1984-1985 as part of the Second International BIOMASS program. Geographical distribution of chlorophyll α observed on the southward leg through the eastern part of the Indian Antarctic Ocean in early-middle December and that on the northward leg through the western part of the Ocean in late February-early March coincided with the previous JARE observations. Comparing the data obtained on both legs, seasonal difference was also indicated; level of chlorophyll was high in December but low in February-March. Maximum concentration reached 1.55μg/ℓ in the north of the Antarctic Convergence in December. Variable, positive or negative relationships between temperature and chlorophyll α were observed in the zones of the Subtropical Convergence, Subantarctic Front and Antarctic Convergence

Characterization of glycoprotein obtained from the skin mucus of an Antarctic fish, Trematomus bernacchii

The epithelial secretions were collected by scraping the skin of Trematomus bernacchii and seven species of temperate-water fishes and examined for the mucous glycoproteins by gel filtration on a Sepharose CL-4B column. In most cases, the glycoproteins were excluded at the void volume and separated from other mucous constitutents. The yields of the glycoproteins resolved were usually high (35-45%) in the following fishes secreting large quantities of thick mucus from their epidermis: Callionymus lunatus, Misgurnus anguillicaudatus, Anguilla japonica and Leiognathus nuchalis. A fish with hard scales, Carassius auratus, gave a mucous glycoprotein in a low yield (8.4%). Similarly, the glycoproteins of T. bernacchii, Trachurus japonicus and Acanthogobius fiavimanus were obtained in their respective yields of 17.5%, 18.9%, and 14.2%. The carbohydrate composition of the mucous glycoprotein in T. bernacchii was determined to consist of N-acetylneuraminic acid, N-acetylgalactosamine, galactose, mannose, fucose and glucose by analytical methods including thin-layer chromatography, high-performance liquid chromatography and gas-liquid chromatography. The molar ratio of N-acetylneuraminic acid, N-acetylgalactosamine and galactose (1.0:4.8:1.2) suggests that major carbohydrate chains are constituted by such mono- and disaccharide units as JV-acetylgalactosamine, N-acetylneuraminyl-N-acetylgalactosamine, and galactosyl-N-acetylgalactosamine. These carbohydrate units may link through O-glycosidic linkage to threonine and serine residues in the core polypeptide. Assuming such a structure of the carbohydrate unit, it becomes probable that the mucous glycoprotein secreted from T. bernacchii epithelial tissue has a similar ability to depress freezing point for the antifreeze glycoproteins present in the serum

Homo- and heteronuclear two-dimensional covariance solid-state NMR spectroscopy with a dual-receiver system.

Two-dimensional (2D) covariance NMR spectroscopy, which has originally been established to extract homonuclear correlations (HOMCOR), is extended to include heteronuclear correlations (HETCOR). In a (13)C/(15)N 2D chemical shift correlation experiment, (13)C and (15)N signals of a polycrystalline sample of (13)C, (15)N-labeled amino acid are acquired simultaneously using a dual-receiver NMR system. The data sets are rearranged for the covariance data processing, and the (13)C-(15)N heteronuclear correlations are obtained together with the (13)C-(13)C and (15)N-(15)N homonuclear correlations. The present approach retains the favorable feature of the original covariance HOMCOR that the spectral resolution along the indirect dimension is given by that of the detection dimension. As a result, much fewer amounts of data are required to obtain a well-resolved 2D spectrum compared to the case of the conventional 2D Fourier-Transformation (FT) scheme. Hence, one can significantly save the experimental time, or enhance the sensitivity by increasing the number of signal averaging within a given measurement time