A simple method for estimating phytoplankton abundance using a surface seawater monitoring system off Syowa Station during austral summer

A surface seawater monitoring system was used aboard the Shirase to estimate phytoplankton abundance while the icebreaker was anchored in an ice covered area off Syowa Station during the austral summer of 1996/97. A significant positive relationship was observed between the digital output (OP) values of the chlorophyll fluorometer of the system, and chlorophyll a (Chl a) concentrations of the seawater that passed through the system. Using this relationship, OP values were converted into Chl a (Chl a OP). Throughout the present study, the Chl a OP was found to be consistent with temporal changes in Chl a observed in the field near the Shirase, with high Chl a OP values measured in relatively warm and less saline water. These findings suggest that the high Chl a may be derived from the ice-edge phytoplankton blooms that develop in stable waters associated with melting ice. Relatively simple operation without need for complicated maintenance procedures facilitates the ease with which the system can be used. The operation of the system every summer may facilitate the acquisition of data that reveal the long-term variability of phytoplankton biomass under fast ice

Distribution of chlorophyll-a and sea surface temperature in the marginal ice zone (20°E-60°E) in East Antarctica determined using satellite multi-sensor remote sensing during austral summer

We investigated the distribution of chlorophyll-a (Chl-a) and sea surface temperature (SST) off the sea ice region south of 64°S in East Antarctica between 20°E and 60°E during austral summers, 1998-2002. We used satellite multi-sensor remote sensing datasets including ocean color Chl-a, SST and sea ice concentration. High concentrations of Chl-a (>0.5 mg m^(-3)) were generally observed in colder water below 0°C. Phytoplankton blooms were extended into shallow areas along the isobath. SST distribution exhibited two patterns. In the first pattern, warm water located to the north of this region associated with polynya in early spring. The second pattern was characterized by distribution of cold water throughout the study area. A shift of the Antarctic Circumpolar Current (ACC) is considered to affect this difference between SST distributions. The cold water from the Antarctic coastal current mixed with meltwater was expected to provide vertical stability of the water column for phytoplankton blooms. These results suggest that the phytoplankton blooms in this study area during austral summer can be attributed to water conditions affected by melting sea ice, movement of the ACC and sea floor topography

ショウワキチ シュウヘン ニオケル カンソク カラ エラレタ カイヒョウアツ ト スイチュウ コウリョウ ノ ケイケンテキ カンケイ

1996年12月30日,1997年1月3日,11日,17日,29日に,南極昭和基地周辺海域の4点において水中の光合成有効放射(PAR)を測定した.4測点の氷厚及び積雪は,それぞれ2.06-3.64m及び0.04-0.70mであった.海氷直下のPARは,0.1-6.6μmolm^-2s^-1と見積もられた.氷厚と海氷直下のPARの間には,有意な負の相関があった.過去の値からも同様の関係式が得られた.これら極域で得られた全ての値を用いて,氷厚と水中PARの間の経験的関係式を求めた.得られた式は,氷上の雪により空中PARが約20%に減少した後,海氷1mでPARが一桁低くなることを示す.Underwater light intensity was measured as photosynthetically active radiation (PAR) at four sites near Syowa Station, Antarctica, on 30 December 1996, and 3, 11, 17, and 29 January 1997. The sites were covered with several different thicknesses of sea ice (2.06-3.64m) and snow (0.04-0.70m). The estimated PAR intensities just under the sea ice were 0.1-6.6μmolm^-2s^-1. There was a significant negative correlation between sea ice thickness and PAR just under the sea ice. A similar relationship was obtained when the previously reported values in the literature were analyzed. Using data from the present and previous studies, an empirical equation is proposed. The equation implies that snow layer reduces the incidence to about 20% of surface irradiance, and that PAR decreases by one order of magnitude with each 1 m increase of the sea ice thickness

ダイ44ジ ナンキョク チイキ カンソクタイ カンソク ケンキュウ ショウシュウカイ センヨウ カンソクセン ホウコク

「第44次南極地域観測隊観測研究小集会-専用観測船」を、平成14年10月15日、国立極地研究所講堂において開催した。本年度出発する第44次日本南極地域観測隊(the 44th Japanese Antarctic Research Expedition, JARE-44)において実施される、「専用観測船」による海洋観測参加者を中心に34名の参加者があった。本研究小集会では、「専用観測船」航海乗船者へJARE参加の心構え及び安全対策の説明が行われた。併せて、「専用観測船」での希望観測項目の詳細を打ち合わせ、観測スケジュールが改訂された。A workshop on "Marine Science Program in the 44th Japanese Antarctic Research Expedition on a Charter Research Vessel" was held on 15th October 2002 at the convention hall of the National Institute of Polar Research with 34 participants. Most of the participants will join the research cruise organized by the 44th Japanese Antarctic Research Expedition (JARE-44) using a charter vessel. One of the purposes of this workshop is to give detailed information on the JARE system. At the same time, safety guidelines for the cruise were explained. In addition, the work schedule for the cruise was revised based on detailed requests from the participants

Achievement of JARE routine observation of marine biology and its future perspectives

第2回極域科学シンポジウム/第33回極域生物シンポジウム 11月17日（木） 統計数理研究所 3階セミナー室

The whole blood transcriptional regulation landscape in 465 COVID-19 infected samples from Japan COVID-19 Task Force

「コロナ制圧タスクフォース」COVID-19患者由来の血液細胞における遺伝子発現の網羅的解析 --重症度に応じた遺伝子発現の変化には、ヒトゲノム配列の個人差が影響する--. 京都大学プレスリリース. 2022-08-23.Coronavirus disease 2019 (COVID-19) is a recently-emerged infectious disease that has caused millions of deaths, where comprehensive understanding of disease mechanisms is still unestablished. In particular, studies of gene expression dynamics and regulation landscape in COVID-19 infected individuals are limited. Here, we report on a thorough analysis of whole blood RNA-seq data from 465 genotyped samples from the Japan COVID-19 Task Force, including 359 severe and 106 non-severe COVID-19 cases. We discover 1169 putative causal expression quantitative trait loci (eQTLs) including 34 possible colocalizations with biobank fine-mapping results of hematopoietic traits in a Japanese population, 1549 putative causal splice QTLs (sQTLs; e.g. two independent sQTLs at TOR1AIP1), as well as biologically interpretable trans-eQTL examples (e.g., REST and STING1), all fine-mapped at single variant resolution. We perform differential gene expression analysis to elucidate 198 genes with increased expression in severe COVID-19 cases and enriched for innate immune-related functions. Finally, we evaluate the limited but non-zero effect of COVID-19 phenotype on eQTL discovery, and highlight the presence of COVID-19 severity-interaction eQTLs (ieQTLs; e.g., CLEC4C and MYBL2). Our study provides a comprehensive catalog of whole blood regulatory variants in Japanese, as well as a reference for transcriptional landscapes in response to COVID-19 infection

DOCK2 is involved in the host genetics and biology of severe COVID-19

「コロナ制圧タスクフォース」COVID-19疾患感受性遺伝子DOCK2の重症化機序を解明 --アジア最大のバイオレポジトリーでCOVID-19の治療標的を発見--. 京都大学プレスリリース. 2022-08-10.Identifying the host genetic factors underlying severe COVID-19 is an emerging challenge. Here we conducted a genome-wide association study (GWAS) involving 2, 393 cases of COVID-19 in a cohort of Japanese individuals collected during the initial waves of the pandemic, with 3, 289 unaffected controls. We identified a variant on chromosome 5 at 5q35 (rs60200309-A), close to the dedicator of cytokinesis 2 gene (DOCK2), which was associated with severe COVID-19 in patients less than 65 years of age. This risk allele was prevalent in East Asian individuals but rare in Europeans, highlighting the value of genome-wide association studies in non-European populations. RNA-sequencing analysis of 473 bulk peripheral blood samples identified decreased expression of DOCK2 associated with the risk allele in these younger patients. DOCK2 expression was suppressed in patients with severe cases of COVID-19. Single-cell RNA-sequencing analysis (n = 61 individuals) identified cell-type-specific downregulation of DOCK2 and a COVID-19-specific decreasing effect of the risk allele on DOCK2 expression in non-classical monocytes. Immunohistochemistry of lung specimens from patients with severe COVID-19 pneumonia showed suppressed DOCK2 expression. Moreover, inhibition of DOCK2 function with CPYPP increased the severity of pneumonia in a Syrian hamster model of SARS-CoV-2 infection, characterized by weight loss, lung oedema, enhanced viral loads, impaired macrophage recruitment and dysregulated type I interferon responses. We conclude that DOCK2 has an important role in the host immune response to SARS-CoV-2 infection and the development of severe COVID-19, and could be further explored as a potential biomarker and/or therapeutic target