Impacts of increased atmospheric CO_2 concentration on photosynthesis and growth of micro-and macro-algae

Marine photosynthesis drives the oceanic biological CO2 pump to absorb CO2 from the atmosphere, which sinks more than one third of the industry-originated CO2 into the ocean. The increasing atmos-pheric CO2 and subsequent rise of pCO2 in seawater, which alters the carbonate system and related chemical reactions and results in lower pH and higher HCO3- concentration, affect photosynthetic CO2 fixation processes of phytoplanktonic and macroalgal species in direct and/or indirect ways. Although many unicellular and multicellular species can operate CO2-concentrating mechanisms (CCMs) to util-ize the large HCO3- pool in seawater, enriched CO2 up to several times the present atmospheric level has been shown to enhance photosynthesis and growth of both phytoplanktonic and macro-species that have less capacity of CCMs. Even for species that operate active CCMs and those whose photo-synthesis is not limited by CO2 in seawater, increased CO2 levels can down-regulate their CCMs and therefore enhance their growth under light-limiting conditions (at higher CO2 levels, less light energy is required to drive CCM). Altered physiological performances under high-CO2 conditions may cause genetic alteration in view of adaptation over long time scale. Marine algae may adapt to a high CO2 oceanic environment so that the evolved communities in future are likely to be genetically different from the contemporary communities. However, most of the previous studies have been carried out under indoor conditions without considering the acidifying effects on seawater by increased CO2 and other interacting environmental factors, and little has been documented so far to explain how physi-ology of marine primary producers performs in a high-CO2 and low-pH ocean.     

Modulation of Macrophage Activation State Protects Tissue from Necrosis during Critical Limb Ischemia in Thrombospondin-1-Deficient Mice

Background

Macrophages, key regulators of healing/regeneration processes, strongly infiltrate ischemic tissues from patients suffering from critical limb ischemia (CLI). However pro-inflammatory markers correlate with disease progression and risk of amputation, suggesting that modulating macrophage activation state might be beneficial. We previously reported that thrombospondin-1 (TSP-1) is highly expressed in ischemic tissues during CLI in humans. TSP-1 is a matricellular protein that displays well-known angiostatic properties in cancer, and regulates inflammation in vivo and macrophages properties in vitro. We therefore sought to investigate its function in a mouse model of CLI.

Methods and Findings

Using a genetic model of tsp-1 ^−/− mice subjected to femoral artery excision, we report that tsp-1 ^−/− mice were clinically and histologically protected from necrosis compared to controls. Tissue protection was associated with increased postischemic angiogenesis and muscle regeneration. We next showed that macrophages present in ischemic tissues exhibited distinct phenotypes in tsp-1 ^−/− and wt mice. A strong reduction of necrotic myofibers phagocytosis was observed in tsp-1 ^−/− mice. We next demonstrated that phagocytosis of muscle cell debris is a potent pro-inflammatory signal for macrophages in vitro. Consistently with these findings, macrophages that infiltrated ischemic tissues exhibited a reduced postischemic pro-inflammatory activation state in tsp-1 ^−/− mice, characterized by a reduced Ly-6C expression and a less pro-inflammatory cytokine expression profile. Finally, we showed that monocyte depletion reversed clinical and histological protection from necrosis observed in tsp-1 ^−/− mice, thereby demonstrating that macrophages mediated tissue protection in these mice.

Conclusion

This study defines targeting postischemic macrophage activation state as a new potential therapeutic approach to protect tissues from necrosis and promote tissue repair during CLI. Furthermore, our data suggest that phagocytosis plays a crucial role in promoting a deleterious intra-tissular pro-inflammatory macrophage activation state during critical injuries. Finally, our results describe TSP-1 as a new relevant physiological target during critical leg ischemia.     

半滑舌鳎早期形态及发育特征

半滑舌鳎卵子为分离的球形浮性卵 ,卵径 1 18-1 3 1mm。卵膜薄、光滑、透明 ,具弹性。多油球 ,一般为 97-12 5个 ,多数在 10 0个左右 ,油球径 0 0 4-0 11mm。在培养水温为 2 0 5-2 2 8℃的条件下 ,卵子授精后 3 7h仔鱼孵出 ,3 0min后仔鱼全部孵出。初孵仔鱼全长 2 56-2 68mm。 1日龄仔鱼 ,出现胸鳍芽。 1 5日龄仔鱼 ,巡游模式基本建立。 2日龄仔鱼 ,逐渐建立外源性摄食关系。 3日龄仔鱼 ,出现鳔泡 ,个体发育进入后期仔鱼期。 18日龄 ,个体发育进入稚鱼期。 2 5日龄稚鱼 ,右眼开始向上移动。 2 7日龄稚鱼 ,右眼已转到头顶。 2 9日龄稚鱼 ,右眼完全转到左侧 ,胸鳍退化 ,各鳍鳍条发育完全。 57日龄 ,个体发育进入幼鱼期。 79日龄幼鱼 ,鳔退化、鳞片发育完全 ,侧线 3条。研究结果表明 :前期仔鱼培育期间 ,除了严格控制适宜的培养水温外 ,仔鱼开口后就应及时投喂一定密度的适口饵料 ,这是苗种培育中不可忽视的重要环节和技术措施之一 ;稚鱼变态期间加强鲜活饵料的投喂是提高稚鱼变态成活率的关键所在。仔鱼孵化后出现的管状感觉器官以及背、臀鳍膜上的泡状结构在早期发育阶段的生态和生理作用尚不清楚。半滑舌鳎成鱼无鳔和无胸鳍 ,而在早期发育期间具有鳔泡和胸鳍 ,这是生物个体发育史中祖先特征的重演     

中国对虾（Penaeus chinensis）4个种群的同工酶遗传变异

采用水平淀粉凝胶电泳技术分析了中国对虾（Penaeuschinensis）黄渤海沿岸种群（YP）、朝鲜半岛西海岸种群（KP）和2个养殖种群（CP1和CP2）的同工酶遗传变异水平。每个种群随机选取50尾中国对虾进行同工酶检测。在所分析的12种同工酶编码的20个基因位点中,有4个是多态位点。4个种群的多态位点比例（P0.99）分别为15%、20%、10%和20%。种群平均杂合度（观测值）（Ho）分别为0.014±0.007、0.020±0.010、0.010±0.007和0.033±0.017。4个种群的位点有效等位基因数（Ne）分别为1.015±0.008、1.023±0.011、1.011±0.007和1.042±0.022。杂合子平衡偏离指数（D）分别为+0.037、-0.030、-0.098和-0.030。2个地理种群（YP和KP）的遗传相似性系数（I）和遗传距离（D     

中国外来海洋生物及其影响

到目前为止,我国已从国外引进了鱼类10种、虾类2种、贝类9种、棘皮动物1种、藻类4种进行海水养殖;引进了抗盐植物2种进行盐碱地栽培;海洋水族馆业的发展,引进了数百种观赏性海洋生物;航运业中的船体附着及压舱水排放,无意中带入了几百种外来海洋生物。首先,外来海洋入侵生物与土著海洋生物争夺生存空间与食物,危害我国土著海洋生物的生存。其次,海洋外来生物通过与亲缘关系接近的物种进行杂交,降低我国海洋土著生物的遗传质量,造成遗传污染。再次,外来海洋生物可能带来病原生物,对海洋生态环境造成巨大的危害。此外,近些年来,我国沿海赤潮越来越严重,其重要原因之一是外来生存能力较强的赤潮生物的危害。     

Brassinolide Effect on Growth of Apical Meristems, Ethylene Production, and Abscisic Acid Content in Potato Tubers

Treatment of intact potato (Solanum tuberosum L., cv. Nevskii) tubers with 24-epibrassinolide (EB) resulted in prolonged deep dormancy, increased production of ethylene and higher contents of free and bound abscisic acid (ABA) in buds. EB at the most efficient concentration 0.021 mg dm^–3, applied immediately after tuber harvest, inhibited sprouting by 36 – 38 d, increased ethylene formation after 1 and 7 d of storage by almost 300 and 150%, respectively, and increased the content of both free and bound ABA during the whole period of storage (on average by about 80%). Electron microscopic and morphometric studies showed that EB brings about a decrease in cell volume in tunica and all types of meristems and an increase in the number of vacuoles, accompanied by a decrease in their volume.     

长江三峡地区上震旦统稳定同位素异常及地层意义

三峡地区广泛发育的上震旦统,及下伏的南沱组和古城组冰碛层,有良好的生物地层控制及全球对比意义。新秭归城附近的雾河剖面,自南沱组顶部到水井沱组下部出露有利于化学地层学研究的一系列碳酸盐岩沉积,对这一剖面的碳,氧,锶同位素研究发现：1）碳,锶和氧同位素在陡山沱组顶部到灯影组底部存在明显异常;2）碳同位素在寒武系-前寒武系界线附近有负异常;3）碳同位素和锶同位素在剖面上的演化具有全球对比意义;4）陡山沱组顶部到灯影组底部的碳,锶同位素异常,与可能存在末远古纪的冰期,即所谓的“后Marinoan冰期”有关。     

Shifts in bacterial community composition associated with increased carbon cycling in a mosaic of phytoplankton blooms

Marine microbes have a pivotal role in the marine biogeochemical cycle of carbon, because they regulate the turnover of dissolved organic matter (DOM), one of the largest carbon reservoirs on Earth. Microbial communities and DOM are both highly diverse components of the ocean system, yet the role of microbial diversity for carbon processing remains thus far poorly understood. We report here results from an exploration of a mosaic of phytoplankton blooms induced by large-scale natural iron fertilization in the Southern Ocean. We show that in this unique ecosystem where concentrations of DOM are lowest in the global ocean, a patchwork of blooms is associated with diverse and distinct bacterial communities. By using on-board continuous cultures, we identify preferences in the degradation of DOM of different reactivity for taxa associated with contrasting blooms. We used the spatial and temporal variability provided by this natural laboratory to demonstrate that the magnitude of bacterial production is linked to the extent of compositional changes. Our results suggest that partitioning of the DOM resource could be a mechanism that structures bacterial communities with a positive feedback on carbon cycling. Our study, focused on bacterial carbon processing, highlights the potential role of diversity as a driving force for the cycling of biogeochemical elements.