National Museum of Plant History of China

ＴｈｅＮａｔｉｏｎａｌＭｕｓｅｕｍｏｆＰｌａｎｔＨｉｓｔｏｒｙｏｆＣｈｉｎａｉｓａｂｒａｎｃｈｏｆｈｅｒｂａｒｉｕｍ,ＩｎｓｔｉｔｕｔｅｏｆＢｏｔａｎｙ,ｔｈｅＣｈｉｎｅｓｅＡｃａｄｅｍｙｏｆＳｃｉｅｎｃｅｓ．Ｉｔｗａｓｂｕｉｌｔｉｎ１９９６ａｎｄｏｆｆｉｃｉａｌｌｙａｐｐｒｏｖｅｄｂｙｔｈｅＣｈｉｎｅｓｅＡｃａｄｅｍｙｏｆＳｃｉｅｎｃｅｓｉｎ１９９８．ＩｔｗａｓｉｎｓｃｒｉｂｅｄｂｙＺｈｏｕＧｕａｎｇｚｈａｏ,Ｔｈｅｖｉｃｅ -ＣｈａｉｒｍａｎｏｆＳｔａｎｄｉｎｇＣｏｍｍｉｔｔｅｅｏｆＣｈｉｎｅ…     

川东北二叠纪吴家坪期牙形石（刺）序列及其世界对比

对四川省宣汉县渡口和南江县桥亭吴家坪期地层的系统采集和研究结果表明,吴家坪期至少包括７个牙形石带,自下而上为Ｃｌａｒｋｉｎａｄｕｋｏｕｅｎｓｉｓ带,Ｃ．ａｓｙｍｍｅｔｒｉｃａ带,Ｃ．ｌｅｖｅｎｉ带,Ｃ．ｇｕａｎｙｕａｎｅｎｓｉｓ带,Ｃ．ｔｒａｎｓｃａｕｃａｓｉｃａ带,Ｃ．ｏｒｉｅｎｔａｌｉｓ和Ｃ．ｉｎｆｌｅｃｔａ带。其中,前３个带的层位低于一直作为吴家坪期早期的Ｃ．ｌｉａｎｇｓｈａｎｅｎｓｉｓ带。吴家坪阶的顶界以置于Ｃ．ｉｎｆｌｅｃｔａ带与Ｃ．ｓｕｂｃａｒｉｎａｔａ带之间较妥。同时,建立了Ｃｌａｒｋｉｎａｄｕｋｏｕｅｎｓｉｓ,Ｃ．ａｓｙｍｍｅｔｒｉｃａ,Ｃ．ｂｉｚａｒｒｅｎｓｉｓ,Ｃ．ｄａｘｉａｎｅｎｓｉｓ,Ｃ．ｄｅｍｉｃｏｒｎｉｓ,Ｃ．ｉｎｆｌｅｃｔａ,Ｃ．ｌｏｎｇｉｃｕｓｐｉｄａｔａ等７个新种。     

我国南海海龟资源的调查与保护研究现状与展望

我国南海海龟资源的调查与保护研究现状与展望王亚民（中华人民共和国农业部水产司,北京１０００２６）ＡｃｈｉｅｖｅｍｅｎｔａｎｄＰｅｒｓｐｅｃｔｉｖｅｏｆｔｈｅＲｅｓｅａｒｃｈｅｓｏｎＳｏｕｔｂＣｈｉｎａＳｅａＴｕｒｔｌｅＲｅｓｏｕｒｃｅｓａｎｄＰｒｏｔｅｃｔｉｏｎｉｎＣｂｉｎａ￥ＷａｎｇＹａｍｉｎ（ＤｉｖｉｓｉｏｎｏｆＳｃｉｅｎｃｅａｎｄＴｅｃｈｎｏｌｏｇｙ,ＤｅｐａｒｔｍｅｎｔｏｆＦｉｓｈｅｒｙ,Ｐｅｏｐｌｅ’ｓＲｅｐｕｂｌｉｃｏｆＣｈｉｎａＭｉｎｉｓｔｒｙｏｆＡｇｒｉｃｕｌｔｕｒｅ,Ｂｅｉｊｉｎｇ１０００２６）．ＣｈｉｎｅｓｅＪｏｕｒｎａｌｏｆＥｃｏｌｏｇｙ,１９９３,１２（６）：６０－６１．ＴｈｉｓｐａｐｅｒｉｎｔｒｏｄｕｃｅｓｔｈｅｒｅｓｅａｒｃｈｅｓｉｎｆｉｅｌｄｏｆＳｏｕｔｈＣｈｉｎａＳｅａｔｕｒｔｌｅｒｅｓｏｕｒｃｅｓａｎｄｐｒｏｔｅｃｔｉｏｎｉｎＣｈｉｎａ．ＴｈｅｒｅａｒｅｆｉｖｅｓｐｅｃｉｅｓｓｅａｔｕｒｔｌｅｓｉｎＣｈｉｎａ,ａｂｏｕｔ９０％ｏｆｔｈｅｍｌｉｖｅｉｎＳｏｕｔｈＣｈｉｎａｓｅａ。Ｄｕｒｉｎｇ１９５９－１９８８,３１８４．Ｉｔｓｅａｔｕｒｔｌｅｗｅｒｅｃａｔｃｈｅｄ（ａｂｏｕｔ     

湖北省吨粮田的现状及其投肥效率分析

湖北省吨粮田的现状及其投肥效率分析孙先（华中农业大学,武汉４３００７０）ＣｕｒｒｅｎｔＳｉｔｕａｔｉｏｎａｎｄＦｅｒｔｉｌｉｚａｔｉｏｎＥｆｆｉｃｉｅｎｃｙｏｆＨｉｇｈＰｒｏｄｕｃｔｉｖｅＣｒｏｐｌａｎｄｓｉｎＨｕｂｅｉＰｒｏｖｉｎｃｅ￥ＳｕｎＸｉａｎ－ｒｏｎｇ（ＣｅｎｔｒａｌＣｈｉｎａＡｇｒｉｃｕｌｔｕｒｅＵｎｉｖｅｒｓｉｔｙ,Ｗｕｈａｎ４３００７０）．ＣｈｉｎｅｓｅＪｏｕｒｎａｌｏｆＥｃｏｌｏｇｙｌ１９９３,１２（２）：５５－５６．Ｓｉｎｃｅ１９９０,ｔｈｅｄｅｖｅｌｏｐｍｅｎｔｏｆｈｉｇｈｐｒｏｄｕｃｔｉｖｅｃｒｏｐｌａｎｄｈａｓｂｅｅｎａｃｃｅｌｅｒａｔｅｄａｎｄｔｈｅｅｆｆｅｃｔｏｆｉｔｓｙｉｅｌｄａｎｄｂｅｎｅｆｉｔｉｎｃｒｅａｓｅｉｓｖｅｒｙｏｂｖｉｏｕｓ,Ｂｕｔ,ｗｈｅｔｈｅｒｈｉｇｈｙｉｅｌｄａｎｄｈｉｇｈｅｆｆｉｃｉｅｎｃｙｃａｎｂｅｓｙｎｃｈｒｏｎｉｚｅｄｄｅ－ｓｅｒｖｅｓｃｌｏｓｅａｔｔｅｎｔｉｏｎ,Ｉｎｔｈｉｓｒｅｓｅａｒｃｈ,７９ｈｉｇｈｙｉｅｌｄｃｒｏｐｐｉｎｇｐａｔｔｅｒｎｓａｒｅｉｎｖｅｓｔｉｇａｔｅｄｆｏｒｔｈｒｅｅｙｅａｒｓｉｎＨｕｂｅｉａｎｄｔｈｅｉｒｅｆｆｉｃｉｅｎ     

贵州蓑藓属一新种

ＴｈｅｒｅａｒｅｓｐｅｃｉｅｓｏｆＭａｃｒｏｍｉｔｒｉｕｍｉｎＧｕｉｚｈｏｕｐｒｏｖｉｎｃｅＣｈｉｎａ .Ａｍｏｎｇｔｈｅｍ ,2ｓｐｅｃｉｅｓａｒｅｅｎ ｄｅｍｉｃｓｐｅｃｉｅｓ ,Ｍ .ｃａｖａｌｅｒｉｅｒＣａｒｄ＆Ｔｈｅｒ .ａｎｄＭ .ｆｏｒｔｕｎａｔｉｉＣａｒｄ＆Ｔｈｅｒ .Ｄｕｒｉｎｇａｒｅｃｅｎｔｒｅ -ｅｘａｍｉｎａｔｉｏｎｏｆｓｏｍｅＭａｃｒｏｍｉｔｒｉｕｍｓｐｅｃｉｍｅｎｓｆｒｏｍｔｈｉｓｒｅｇｉｏｎ .ＡｔａｘｏｎｃｌｏｓｅｌｙｒｅｌａｔｅｄｔｏｓｐｅｃｉｅｓｏｆｔｈｅＭ .ｆｅｒｒｉｅｉＣａｒ…     

毛药山茶——中国广东山茶属一新种

毛药山茶　新种　图 1ＣａｍｅｌｌｉａｒｅｎｓｈａｎｘｉａｎｇｉａｅＣ .Ｘ .ＹｅｅｔＸ .Ｑ .Ｚｈｅｎｇ ,ｓｐ .ｎｏｖ . (Ｓｕｂｇｅｎ .ＭｅｔａｃａｍｅｌｌｉａＨ .Ｔ .Ｃｈａｎｇ,Ｓｅｃｔ.ＥｒｉａｎｄｒｉａＣｏｈｅｎ Ｓｔｕａｒｔ) .Ｆｉｇ .1ＳｐｅｃｉｅｓＣ .ｃｒａｔｅｒａｅＨ .Ｔ .ＣｈａｎｇｅｔＣ .ｔｒｉｇｏｎｏｃａｒｐａｅＨ .Ｔ .Ｃｈａｎｇａｆｆｉｎｉｓ,ｓｅｄｉｌｌａｆｌｏｒｉｂｕｓｒｕｂｒｉｓ (ｔｅｓｔｅｎｏｔｕｌａｃｏｌｌｅｃｔｏｒｉｓ) ,ｂｒａｃｔｅｏｌｉｓｓｅｐａｌｉｓｑｕｅｕｔｒｉｎｑ…     

A novel liver-directed gene delivery system using an autonomously replicating vector specifically expressed in AFP positive hepatoma cells

Ｔｈｅｃｕｒｒｅｎｔｔｒｅａｔｍｅｎｔｓｏｆｈｅｐａｔｏｃｅｌｌｕｌａｒｃａｒｃｉｎｏｍａ(ＨＣＣ)ａｒｅｄｉｓａｐｐｏｉｎｔｉｎｇａｎｄａｒｅｌｉｍｉｔｅｄｔｏｔｕｍｏｒｒｅｓｅｃｔｉｏｎｏｒｔｒａｎｓｐｌａｎｔａｔｉｏｎ.ＧｅｎｅｔｈｅｒａｐｙｉｓａｎａｌｔｅｒｎａｔｉｖｅｓｔｒａｔｅｇｙｔｈａｔｈａｓｂｅｅｎｗｉｄｅｌｙｉｎｖｅｓｔｉｇａｔｅｄｆｏｒｔｈｅｔｒｅａｔｍｅｎｔｏｆｓｏｌｉｄｔｕｍｏｒｓｌｉｋｅＨＣＣ.Ｈｉｇｈｃｏｎｃｅｎｔｒａｔｉｏｎｏｆαｆｅｔｏｐｒｏｔｅｉｎ(ＡＦＰ)ｉｓｃｕｒ…     

Correlation between expression of cadherin and gap junctional communication in human lung carcinoma cells

ＣａｄｈｅｒｉｎｓａｒｅｍｅｍｂｒａｎｏｕｓＣａ2+ｄｅｐｅｎｄｅｎｔ,ｈｏｍｏｐｈｉｌｉｃ,ａｄｈｅｓｉｏｎｍｏｌｅｃｕｌｅｓｔｈａｔａｒｅａｓｓｕｍｅｄｔｏｐｌａｙｅｓｓｅｎｔｉａｌｒｏｌｅｓｉｎｃｅｌｌｒｅｃｏｇｎｉｔｉｏｎ,ｃｅｌｌｓｏｒｔｉｎｇ,ｅｍｂｒｙｏｎｉｃｍｏｒｐｈｏｇｅｎｅｓｉｓａｎｄｓｉｇｎａｌｔｒａｎｓｄｕｃｔｉｏｎ[1,2].ＴｈｅｓｅｔｒａｎｓｍｅｍｂｒａｎｅｍｏｌｅｃｕｌｅｓｆｏｒｍａｐｌａｑｕｅｔｈｒｏｕｇｈｉｔｓｃｙｔｏｐｌａｓｍｉｃｄｏｍａｉｎａｔＣｔａｉｌｗｉｔｈｔｈｅ…     

广西唇柱苣苔属一新种

融安唇柱苣苔　新种　图 1ＣｈｉｒｉｔａｒｏｎｇａｎｅｎｓｉｓＤ .ＦａｎｇｅｔＹ .Ｇ .Ｗｅｉ,ｓｐ .ｎｏｖ .(Ｃｈｉｒｉｔａｓｅｃｔ.ＧｉｂｂｏｓａｃｃｕｓＣ .Ｂ .Ｃｌａｒｋｅ) .Ｆｉｇ .1ＨａｂｉｔｕｓｉｍｉｌｉｓＣ .ｇｅｍｅｌｌａｅＤ .Ｗｏｏｄ ,ｑｕａｅｒｈｉｚｏｍａｔｅｓｔｏｌｏｎｉｆｅｒｏ ,ｆｏｌｉｉｓｅｌｌｉｐｔｉｃｉｓｖｅｌｏｂｏｖａｔｉｓｍｉｎｏｒｉｂｕｓｉｎｔｅｇｒｉｓ,ｃｙｍｉｓ 1～ 4＿ｆｌｏｒｉｓ,ｃｏｒｏｌｌａｅｔｕｂｉｏｒｅ 1 7ｍｍｄｉａｍ .,ｓｔａｍｉｎｕｍｆｉｌａｍｅｎｔｉｓｓ…     

丘陵地区农户生态系统演替分析

丘陵地区农户生态系统演替分析曹凑贵（华中农业大学,武汉４３００７０）ＥｖｏｌｕｔｉｏｎａｒｙＡｎａｌｙｓｉｓｏｎＨｏｕｓｅｋｏｌｄＥｃｏｓｙｓｔｅｍｉｎＨＩＩＩｙＲｅｇｉｏｎｓ￥ＣａｏＣｏｕｇｕｉ（ＣｅｎｔｒａｌＣｈｉｎａＡｇｒｉｃｕｌｄｔｕｒａｌＵｎｉｖｅｒｓｉｔｙ,Ｗｕｈａｎ４３００７０）．ＣｈｉｎｅｓｅＪｏｕｒｎａｌｏｆＥｃｏｌｏｇｙ,１９９３,１２（２）：５３－５４．Ｔｈｅｃｈａｒａｃｔｅｒｉｓｔｉｃｓｏｆｄｉｆｆｅｒｅｎｔｔｙｐｅｈｏｕｓｅｈｏｌｄｅｃｏｓｙｓｔｅｍｓａｎｄｔｈｅｉｒｅｖｏｌｕｔｉｏｎａｒｙｃｏｒｒｅｌａｔｉｏｎｓａｒｅａｎａｌｙｚｅｄｕｓｉｎｇｆｕｚｚｙｃｌｕｓｔｅｒｉｎｇａｎｄｓｙｓｔｅｍｓｙｎｔｈｅｔｉｃｅｖｏｌｕｔｉｏｎｍｅｔｈｏｄｓ,Ｔｈｅｃａｕｓｅａｎｄｄｉｒｅｃｔｉｏｎｏｆａｇｒｉｃｕｌｔｕｒａｌｄｅｖｅｌｏｐｍｅｎｔｉｎｈｉｌｌｙｒｅｇｉｏｎｓａｒｅｒｅｖｅａｌｅｄａｎｄｓｕｇｇｅｓｔｉｏｎｓｏｎｄｅｖｅｌｏｐｉｎｇｅｃｏ－ａｇｒｉｃｕｌｔｕｒａｌｃｏｎｓｔｒｕｃｔｉｏｎｉｎｌｏｗｅｒｐｒｏｄｕｃｔｉｖｅｈｉｌｌｙｒｅｇｉｏｎｓａｒｅｍａｄｅ．Ｋｅｙｗｏｒｄｓ：ｈｏ     

Effect of microorganisms and seasonal factors on the isotope composition of organic carbon from Black Sea suspensions

The isotopic composition of particulate organic carbon (POC) from the Black Sea deep-water zone was studied during a Russian-Swiss expedition in May 1998. POC from the upper part of the hydrogen sulfide zone (the C-layer) was found to be considerably enriched with the 12C isotope, as compared to the POC of the oxycline and anaerobic zone. In the C-layer waters, the concurrent presence of dissolved oxygen and hydrogen sulfide and an increased rate of dark CO2 fixation were recorded, suggesting that the change in the POC isotopic composition occurs at the expense of newly formed isotopically light organic matter of the biomass of autotrophic bacteria involved in the sulfur cycle. In the anaerobic waters below the C-layer, the organic matter of the biomass of autotrophs is consumed by the community of heterotrophic microorganisms; this results in weighting of the POC isotopic composition. Analysis of the data obtained and data available in the literature allows an inference to be made about the considerable seasonable variability of the POC delta 13C value, which depends on the ratio of terrigenic and planktonogenic components in the particulate organic matter.     

The effect of microorganisms and seasonal factors on the isotopic composition of particulate organic carbon from the black sea

The isotopic composition of particulate organic carbon (POC) from the Black Sea deep-water zone was studied during a Russian-Swiss expedition in May 1998. POC from the upper part of the hydrogen sulfide zone (the C-layer) was found to be considerably enriched with the¹²C isotope, as compared to the POC of the oxycline and anaerobic zone. In the C-layer waters, the concurrent presence of dissolved oxygen and hydrogen sulfide and an increased rate of dark CO₂ fixation were recorded, suggesting that the change in the POC isotopic composition occurs at the expense of newly formed isotopically light organic matter of the biomass of autotrophic bacteria involved in the sulfur cycle. In the anaerobic waters below the C-layer, the organic matter of the biomass of autotrophs is consumed by the community of heterotrophic microorganisms; this results in weighting of the POC isotopic composition. Analysis of the data obtained and data available in the literature allows an inference to be made about the considerable seasonable variability of the POC δ¹³C value, which depends on the ratio of terrigenic and planktonogenic components in the particulate organic matter.     

Stimulation of Diesel Fuel Biodegradation by Indigenous Nitrogen Fixing Bacterial Consortia

Abstract Successful stimulation of N₂ fixation and petroleum hydrocarbon degradation in indigenous microbial consortia may decrease exogenous N requirements and reduce environmental impacts of bioremediation following petroleum pollution. This study explored the biodegradation of petroleum pollution by indigenous N₂ fixing marine microbial consortia. Particulate organic carbon (POC) in the form of ground, sterile corn-slash (post-harvest leaves and stems) was added to diesel fuel amended coastal water samples to stimulate biodegradation of petroleum hydrocarbons by native microorganisms capable of supplying a portion of their own N. It was hypothesized that addition of POC to petroleum amended water samples from N-limited coastal waters would promote the growth of N₂ fixing consortia and enhance biodegradation of petroleum. Manipulative experiments were conducted using samples from coastal waters (marinas and less polluted control site) to determine the effects of POC amendment on biodegradation of petroleum pollution by native microbial consortia. Structure and function of the microbial consortia were determined by measurement of N₂ fixation (acetylene reduction), hydrocarbon biodegradation (¹⁴C hexadecane mineralization), bacterial biomass (AODC), number of hydrocarbon degrading bacteria (MPN), and bacterial productivity (³H-thymidine incorporation). Throughout this study there was a consistent enhancement of petroleum hydrocarbon degradation in response to the addition of POC. Stimulation of diesel fuel biodegradation following the addition of POC was likely attributable to increases in bacterial N₂ fixation, diesel fuel bioavailability, bacterial biomass, and metabolic activity. Toxicity of the bulk phase water did not appear to be a factor affecting biodegradation of diesel fuel following POC addition. These results indicate that the addition of POC to diesel-fuel-polluted systems stimulated indigenous N₂ fixing microbial consortia to degrade petroleum hydrocarbons. Received: 29 December 1998; Accepted: 6 April 1999     

2010年夏季珠江口海域颗粒有机碳的分布特征及其来源

于2010年8月对珠江口海域20个站位的颗粒有机碳(POC)进行采样,分析了POC的空间分布特征,讨论了POC与环境因子之间的关系,并利用碳稳定同位素(δ13C)分析了POC的来源及其贡献率。结果显示,研究区域POC的浓度范围98.5—1929.8μg/L,平均浓度541.9μg/L,空间分布总体呈现自北部海域向中部海域逐渐降低,中部海域至南部海域又逐渐升高,底层大于表层的特点。总悬浮颗粒物、叶绿素a、水动力是影响POC空间分布的重要原因。研究区域总悬浮颗粒物δ13C值的变化范围-27.05‰—-21.03‰,平均为-24.57‰,反映出珠江口海域颗粒有机碳为陆源和水生源混合来源,其分布呈现沿盐度梯度自口门内向口门外逐渐递增,底层高于表层的特点。陆源输入和海洋生物生产是影响δ13C值分布的主要原因。运用二元混合模型计算得知,珠江口北部和中部海域POC以陆源有机碳为主,贡献率平均为64%;南部海域POC以水生源有机碳为主,贡献率平均为68%。与20多年前相比,POC的分布特征与来源已经发生了改变,珠江口海域含沙量减少与营养盐含量增加可能是导致POC组成发生变化的主要原因。     

Particulate and Dissolved Organic Carbon Production by the Heterotrophic Nanoflagellate Pteridomonas danica Patterson and Fenchel

Abstract We established a budget of organic carbon utilization of a starved heterotrophic nanoflagellate, Pteridomonas danica, incubated in batch cultures with Escherichia coli as model prey. The cultures were sampled periodically for biomass determinations and total organic carbon dynamics: total organic carbon, total organic carbon <1 μm, and dissolved organic carbon (DOC, <0.2 μm). During the 22 h incubation period, P. danica underwent biovolume variations of 3.2-fold. Gross growth efficiency was 22% and net growth efficiency 40%. P. danica respired 33% and egested 44% of the ingested E. coli carbon during lag and exponential growth phases. The form of the organic carbon egested varied. Of the total ingested carbon, 9% was egested in the form of DOC and occurred mainly during the exponential growth phase; 35% was egested in the form of particulate organic carbon (POC), ranging in size from 0.2 to 1 μm, and took place during the lag phase. P. danica could have reingested as much of 58% of this previously produced POC during the exponential growth phase as food scarcity increased. We concluded that POC egestion by flagellates could represent a significant source of submicrometric particles and colloidal organic matter. In addition, flagellate reingestion of egested POC could play a nonnegligible role in the microbial food web. Finally, the methodology reported in this study has proved to be a useful tool in the study of carbon metabolism in aquatic microorganisms. Received: 31 July 1998; Accepted: 2 March 1999     

Bacterial abundance and production in river sediments as related to the biochemical composition of particulate organic matter (POM)

The major proportion of heterotrophic activity in running waters islocalized on the solid surfaces of sediments in the benthic and hyporheic zoneand is dominated by microorganisms. However, this assertion is based on thestudies of small streams, and little is known about the microbial metabolism oforganic matter in river ecosystems. We therefore explored the relationshipsbetween bacterial abundance and production and the gradients of organic matterquality and quantity in sediments of a sixth-order lowland river (Spree,Germany). We found vertical gradients of detrital variables (particulateorganicmatter (POM), particulate organic carbon (POC), nitrogen (PN), and protein) andof bacterial variables (abundance, production, turnover time, and proportion ofbacterial carbon in total POC) in two different sediment types. These gradientswere steeper in stratified sediments than in the shifting sediments. Detritalvariables correlated strongly with bacterial abundance and production. The bestcorrelation was found for detrital variables indicating substrate quantity andquality (r_S = 0.90 for PN with abundance). Although bacterialbiomasscomprised only 0.7% of the POC (1.9% of PN, 3.4% of the protein) in sediments,the turnover of sedimentary organic carbon was fast (median = 62d), especially in the shifting sediments. Our findings demonstratethat sediment dynamics significantly foster organic carbon metabolism in riversystems. Thus, these sediments, which are typical for lowland rivers, stronglyinfluence the metabolism of the whole ecosystem.     

Evidence for microbial attenuation of particle flux in the Amundsen Gulf and Beaufort Sea: elevated hydrolytic enzyme activity on sinking aggregates

Export of autochthonously produced particulate organic carbon (POC) is a globally important mechanism for sequestering carbon in the deep sea. The role of microbial hydrolytic activity in attenuating POC flux is generally understudied, and particularly complex on Arctic continental shelves influenced by other sources of POC. To evaluate this role, we used fluorogenic substrate analogs to measure extracellular enzyme activity (EEA) associated with particle size fractions considered suspended (1–70 μm) and sinking (>70 μm). Samples were collected by in situ filtration at depths of 25–100 m at ten stations (156–1,142 m deep) in the Amundsen Gulf and Beaufort Sea in June–July, 2008, during the Circumpolar Flaw Lead project. Significant positive correlations observed between EEA and both chlorophyll a and δ¹³C_POC suggest that EEA is elevated in waters dominated by marine-derived POC. No difference in bulk EEA was observed between size fractions, but POC- and cell-specific EEA was significantly elevated on sinking aggregates. Calculations show that 2–44% of carbon retention in surface waters could be attributed to mobilization by enzymes associated with sinking aggregates, and up to 57% if enzymes associated with suspended particles are included. Model results suggest that microbial attenuation of POC below the euphotic zone is a quantitatively important mechanism for carbon loss, especially when particles are sinking slowly. The role of microbes in attenuating POC flux on Arctic shelves appears to have been underestimated previously and may become increasingly important if climate warming brings increased marine productivity.     

Role of aquatic surface microlayer in the dynamics of nutrients and organic compounds in lakes,with implications for their ecotones

The origin and mechanisms of formation of aquatic surface microlayers are reviewed, and processes within the layer responsible for enrichment of inorganic and organic substances, particles, and microorganisms are discussed. In a study of the chemical and biological composition of microlayers in three lakes of different levels of productivity, surface slicks were sampled with a revolving cylinder coated with hydrophilic Teflon. DOC, POC, DON and various forms of phosphorus were enriched in the microlayer compared to those in the subsurface water. In eutrophic and oligotrophic lakes the DOC:DON ratio shows that the slicks were more influenced by allochtonous sources than was the subsurface water, which indicates that processes in the ecotone influence the microlayer composition.     

Contribution of small mountainous rivers to particulate organic carbon input in the Bay of Biscay

The Nivelle River, a typical Pyrenean mountainous watershed reaching the Bay of Biscay (Atlantic Ocean), was sampled with high resolution during 1996. The particulate organic carbon (POC) contents during successive floods shows that there is a graduated impoverishment of the organic fraction of suspended particulate matter (SPM) from the first flood to the next ones, reaching a threshold value (3%) attributed to allochtonous fraction (soil). On the basis of the high frequency data of water discharge and POC concentration, an annual POC flux was established: 845 tons, corresponding to a specific POC flux of 5.3 tC km⁻² yr⁻¹. This value was obtained during a dry period and must be considered as a minimum value for longer time scale. The POC originated mostly from soil (55%) and riparian/litter (~40%) with a very minor (<5%) contribution of autochthonous POC. Thirty-two percent of the annual POC flux was carried in 1% of time and 66% in 10% of time. The specific POC yield, 5.3 tC km⁻² yr⁻¹, if extended to the whole mountainous area of the southern coast of the Bay of Biscay (19,000 km²), leads to an estimated POC flux around 100,000 t yr⁻¹. Although small Cantabrian mountainous rivers contributed to only 28% of the freshwater discharge in the Bay of Biscay, their POC load was estimated to account for 70% of the total POC inputs in the Bay.     

Targeted deletion of A2A adenosine receptors attenuates the protective effects of myocardial postconditioning

Endogenous adenosine is an important ligand trigger for the cardioprotective effects of postconditioning (POC), yet it is unclear which adenosine receptor subtype is primarily responsible. To evaluate the role of A(2A) adenosine receptors in POC-induced protection, global ischemia-reperfusion was performed with and without POC in isolated wild-type (WT) and A(2A) adenosine receptor knockout (A(2A)KO) mouse hearts. Injury was measured in terms of postischemic functional recovery and release of cardiac troponin I (cTnI). Activation of protective signaling with POC was assessed by Akt and extracellular signal-regulated kinase (ERK) 1/2 phosphorylation. In WT hearts, POC improved recovery of postischemic developed pressure in early (81.6 +/- 6.4% of preischemic baseline vs. 37.5 +/- 5.6% for non-POC WT at 1 min) and late (62.2 +/- 4.2% of baseline vs. 45.5 +/- 5.3% for non-POC WT at 30 min) reperfusion, reduced cTnI release by 37%, and doubled the phosphorylation of both Akt and ERK1/2. These beneficial effects of POC were blocked by treatment with the selective A(2A) adenosine receptor antagonist ZM-241385 during reperfusion. Postischemic functional recovery, cTnI release, and phosphorylation of Akt and ERK1/2 were not different between non-POC WT and A(2A)KO hearts. In A(2A)KO hearts, POC did not improve functional recovery, reduce cTnI release, nor increase phosphorylation of Akt or ERK1/2. Thus the protective effects of POC are attenuated by both selective A(2A) receptor antagonism and targeted deletion of the gene encoding A(2A) adenosine receptors. These observations support the conclusion that endogenous activation of A(2A) adenosine receptors is an essential trigger leading to the protective effects of POC in isolated murine hearts.