Ocean urea fertilization for carbon credits poses high ecological risks

The proposed plan for enrichment of the Sulu Sea, Philippines, a region of rich marine biodiversity, with thousands of tonnes of urea in order to stimulate algal blooms and sequester carbon is flawed for multiple reasons. Urea is preferentially used as a nitrogen source by some cyanobacteria and dinoflagellates, many of which are neutrally or positively buoyant. Biological pumps to the deep sea are classically leaky, and the inefficient burial of new biomass makes the estimation of a net loss of carbon from the atmosphere questionable at best. The potential for growth of toxic dinoflagellates is also high, as many grow well on urea and some even increase their toxicity when grown on urea. Many toxic dinoflagellates form cysts which can settle to the sediment and germinate in subsequent years, forming new blooms even without further fertilization. If large-scale blooms do occur, it is likely that they will contribute to hypoxia in the bottom waters upon decomposition. Lastly, urea production requires fossil fuel usage, further limiting the potential for net carbon sequestration. The environmental and economic impacts are potentially great and need to be rigorously assessed. (C) 2008 Elsevier Ltd. All rights reserved.

甘肃黄芪对多柔比星心肌病大鼠心肌组织部分基因表达的影响

目的 比较正常大鼠和多柔比星心肌病大鼠心肌组织部分基因表达谱的差异,探讨甘肃黄芪对上述基因表达谱的影响.方法 30只Wistar大鼠随机分3组:对照组即生理盐水组(n=10),多柔比星组(n=10)和黄芪+多柔比星组(n=10).分别从3组心肌组织中抽提总RNA,用Cy3,Cy5荧光标记,经逆转录合成动物来源的eDNA探针;eDNA探针与4000点基因表达谱芯片杂交,结果由软件分析表达信号.结果 共有923条基因出现差异表达,其中586条基因表达下调,337条基因表达上调.凋亡相关基因表达在多柔比星心肌病时上调;氧化和能量代谢相关基因的表达在多柔比星心肌病时下调.6个在多柔比星组上调的基因在黄芪+多柔比星组下调,8个在多柔比星组下调的基因在黄芪+多柔比星组上调,3个在多柔比星组上调的基因在黄芪+多柔比星组表达进一步增强.结论 凋亡和能量代谢障碍及免疫因素在多柔比星心肌病的发病机制中参与作用,甘肃黄芪对多柔比星诱导的心肌病大鼠的心脏保护作用是通过多基因多途径调节相关基因表达而实现的.