980 resultados para Diphtheria toxin fragment B (DTB)
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本文以光敏色素A (phyA)的特异性基因片段RPA3为探针,利用RNA斑点杂交的方法对光敏核不育水稻农垦58S及对照农垦58叶片中phyA mRNA的丰度进行了分析。结果显示:在育性转换敏感期,光周期处理O天时,农垦58S (NK 58S) phyA mR-NA的丰度比农垦58 (NK 58) phyA mRNA的高。光周期处理5天(雌雄蕊原基形成期)及10天(花粉母细胞形成期)时,短日照条件下(SD),NK 58S phyA mRNA的丰度均比NK58高。进一步比较3天龄NK58S及NK58黄化苗中phyA基因表达的差异,发现NK58S phyA mRNA的丰度比NK58高,并且两品种均符合黄化苗中phyA对其mRNA丰度的负调控作用。这一结果进一步证实:甲基化水平低的NK58S phyA基因比NK58 phyA基因更活跃地表达,进而导致转录水平与翻译水平上的差异,最终参与调节NK 58S的育性转换。 另外,通过持续远红光和红光照射黄化水稻幼苗诱导叶绿素合成的实验,分析了NK58S与NK58之间光敏色素生物功能的差异。持续远红光高辐照度反应(FR-HIR)由phyA负责调节,持续红光高辐照度反应(R-HIR)由phyB负责调节。实验结果显示:持续FR使NK58S与NK58合成叶绿素的含量在12 h时达到最高,并且NK58中叶绿素合成的相对效应比NK585高。持续R使NK58S及NK58中叶绿素的含量在24小时连续处理下持续增加,而且在此时间进程中,NK58中叶绿素合成的相对效应也都比NK58S高。这些结果说明在NK58S和NK58中phyA和phyB均参与了叶绿素合成的调节,并且phyA,phyB在NK58S和NK58黄化苗转绿过程中的作用存在差异。
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Algae are the most abundant photosynthetic organisms in marine ecosystems and are essential components of marine food webs. Harmful algal bloom or “HAB” species are a small subset of algal species that negatively impact humans or the environment. HABs can pose health hazards for humans or animals through the production of toxins or bioactive compounds. They also can cause deterioration of water quality through the buildup of high biomass, which degrades aesthetic, ecological, and recreational values. Humans and animals can be exposed to marine algal toxins through their food, the water in which they swim, or sea spray. Symptoms from toxin exposure range from neurological impairment to gastrointestinal upset to respiratory irritation, in some cases resulting in severe illness and even death. HABs can also result in lost revenue for coastal economies dependent on seafood harvest or tourism, disruption of subsistence activities, loss of community identity tied to coastal resource use, and disruption of social and cultural practices. Although economic impact assessments to date have been limited in scope, it has been estimated that the economic effects of marine HABs in U.S. communities amount to at least $82 million per year including lost income for fisheries, lost recreational opportunities, decreased business in tourism industries, public health costs of illness, and expenses for monitoring and management. As reviewed in the report, Harmful Algal Research and Response: A Human Dimensions Strategy1, the sociocultural impacts of HABs may be significant, but remain mostly undocumented.
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Larval and juvenile development of finescale menhaden (Brevoortia gunteri) is described for the first time by using wild-caught individuals from Nueces Bay, Texas, and is compared with larval and juvenile development of co-occurring gulf menhaden (B. patronus). Meristics, morphometrics, and pigmentation patterns were examined as development proceeded. An illustrated series of finescale menhaden is presented to show changes that occurred during development. For finescale menhaden, transformation to the juvenile stage was completed by 17−19 mm standard length (SL). By contrast, transformation to the juvenile stage for gulf menhaden was not complete until 23−25 mm SL. Characteristics useful for separating larval and juvenile finescale menhaden from gulf menhaden included 1) the presence or absence of pigment at the base of the insertion of the pelvic fins; 2) the standard length at which medial predorsal pigment occurs; 3) differences in the number of dorsal fin ray elements; and, 4) the number of vertebrae.