Robust folding of a de novo designed ideal protein even with most of the core mutated to valine

Rie Koga, Mami Yamamoto, Takahiro Kosugi, Naohiro Kobayashi, Toshihiko Sugiki, Toshimichi Fujiwara, Nobuyasu Koga, Robust folding of a de novo designed ideal protein even with most of the core mutated to valine. Proceedings of the National Academy of Sciences. 117 (49), 31149-31156 (2020). DOI: 10.1073/pnas.2002120117

南大洋110E度線の季節海氷域におけるpCO2の変動

第6回極域科学シンポジウム分野横断セッション：[IB1] 海氷域における生物地球化学的研究11月17日（火）　国立極地研究所１階交流アトリウ

表層海水中溶存酸素の高精度連続観測

大気・海洋間の二酸化炭素や酸素の交換量と，その時空間変動要因や，大気中の温室効果ガスの動態を解明するための一環として，表層海水中溶存酸素の高精度連続観測に取り組んでいる．海洋地球研究船「みらい」では，表層海水連続測定装置により，水温・塩分の測定に加え，世界中で広く利用されているAADI社製OPTODEによる溶存酸素，および，蛍光光度計によるクロロフィルaの測定が行われてきた．OPTODEは時間安定性が優れており，連続観測に適していると考えられているが，応答時間が遅い（カタログによれば67%応答時間は20℃で23秒）という問題があった．そこで，船舶CTDO観測で培った高精度溶存酸素測定技術に基づき，2012年度から表層海水連続測定装置に応答時間が早いJFE Advantech社製RINKOを追加した．溶存酸素検出膜の適切なエイジングと標準ガスを用いたセンサー出力値の線形化，および，時間ドリフト補正用の溶存酸素の分析値を取得することで，溶存酸素の高精度連続観測を実現し，北極海，ベーリング海，西部太平洋，南大洋の広範囲でデータを蓄積した．従来のOPTODEと新たに導入したRINKOの比較から，RINKOに比べてOPTODEは約8分遅れて応答していることや，北極海などでの塩分の短時間での大きな変化に対応してOPTODEが不自然に大きく応答することが明らかになった．さらに，RINKOの技術を応用し，センサーを用いた酸素法による基礎生産量の測定を試みている．これらのデータを総合的に解析し，表層海水中の溶存酸素の時空間変動特性を把握し，変動要因の解明を目指す．BE13-19講演要旨 / ブルーアース2013（2013年3月14日～15日, 東京海洋大学品川キャンパス）http://www.godac.jamstec.go.jp/darwin/cruise/mirai/mr12-e03/

Spatial distribution of pCO2 and pCH4 in the surface sea water and overlying air in the Arctic Ocean

第3回極域科学シンポジウム/特別セッション「これからの北極研究」11月28日（水） 国立極地研究所 2階大会議

Interannual-decadal variability of wintertime mixed layer depths in the North Pacific detected by an ensemble of ocean syntheses

The interannual-decadal variability of the wintertime mixed layer depths (MLDs) over the North Pacific is investigated from an empirical orthogonal function (EOF) analysis of an ensemble of global ocean reanalyses. The first leading EOF mode represents the interannual MLD anomalies centered in the eastern part of the central mode water formation region in phase opposition with those in the eastern subtropics and the central Alaskan Gyre. This first EOF mode is highly correlated with the Pacific decadal oscillation index on both the interannual and decadal time scales. The second leading EOF mode represents the MLD variability in the subtropical mode water (STMW) formation region and has a good correlation with the wintertime West Pacific (WP) index with time lag of 3 years, suggesting the importance of the oceanic dynamical response to the change in the surface wind field associated with the meridional shifts of the Aleutian Low. The above MLD variabilities are in basic agreement with previous observational and modeling findings. Moreover the reanalysis ensemble provides uncertainty estimates. The interannual MLD anomalies in the first and second EOF modes are consistently represented by the individual reanalyses and the amplitudes of the variabilities generally exceed the ensemble spread of the reanalyses. Besides, the resulting MLD variability indices, spanning the 1948–2012 period, should be helpful for characterizing the North Pacific climate variability. In particular, a 6-year oscillation including the WP teleconnection pattern in the atmosphere and the oceanic MLD variability in the STMW formation region is first detected

Ocean acidification off the south coast of Japan : A result from time series observations of CO2 parameters from 1994 to 2008

Ocean acidification resulting from increases in present and future atmospheric CO2 levels could seriously affect diverse coastal and oceanic ecosystems. In this work, we determine that a significant trend in ocean acidification is superposed on the large seasonal and interannual variabilities of acidity in surface waters off the south coast of Honshu, Japan, based on our repeated observations of partial pressure of CO2 (pCO2), total inorganic carbon (TCO2), and pH. Multiple regression analysis of TCO2 as a function of temperature, salinity, and timing of observations shows that TCO2 increased at a rate of + 1.23 ± 0.40 μmol kg^[-1] yr^[-1] for the period 1994-2008, while no long-term change has been determined for total alkalinity calculated from TCO2 and pCO2 in seawater. These results indicate that pH and the aragonite saturation state (Ωarag) are decreasing at a rate of -0.020 ± 0.007 decade^[-1] and -0.12 ± 0.05 decade^[-1], respectively. If future atmospheric CO2 levels keep increasing as predicted by the Intergovernmental Panel on Climate Change emission scenario A1FI, which postulates intensive fossil fuel use associated with very rapid economic growth, a further reduction of -0.8 to -1.0 in Ωarag is likely in the next 50 years. Such a rapid reduction of Ωarag could have negative impacts on a variety of calcareous organisms

Recent deceleration of oceanic pCO2 increase in the western North Pacific in winter

Recent changes in oceanic CO2 partial pressure (pCO2^[sea]) have attracted increasing interest as they relate to the increase in atmospheric CO2 and climate change. We report decadal changes in the growth rates of pCO2^[sea] in latitudinal zones from 3°N to 33°N along the repeat hydrographic line at 137°E in the western North Pacific in winter. The growth rates of pCO2^[sea] for 1999-2009 (-0.3 ± 0.9 [mean ± 1σ] to 1.7 ± 0.5 μatm yr^[-1]) were lower than those for 1984-1997 (0.7 ± 0.3 to 2.2 ± 0.6 μatm yr^[-1]) at most latitudes, indicative of the recent notable deceleration of pCO2^[sea] increase. For latitudes around 10-20°N, we attribute the reduction in the growth rate of pCO2^[sea] for 1999-2009 primarily to the reduction in the contribution from dissolved inorganic carbon (DIC) originating from a reduction in carbon accumulation associated with the expansion of the western Subtropical Gyre towards the south