我国亚热带毛竹林CO2通量的变异特征

2010年12月至2011年11月,利用涡度相关技术研究了我国亚热带(浙江)毛竹林生态系统的CO₂通量,分析了毛竹林净生态系统交换量(NEE)、生态系统呼吸量(RE)和生态系统总交换量(GEE)的变化.结果表明: 研究期间,毛竹林各月的NEE均为负值,7月最大,为-99.33 g C·m^-2,11月最小,仅-23.49 g C·m^-2,其变化曲线呈双峰型.各月CO₂通量平均日变化差异明显,9月最大,为-0.60 g CO₂·m^-2·s^-1,1月最小,为-0.30 g CO₂·m^-2·s^-1,且在NEE正负转换的时间点上呈明显的季节变化特征;全年RE呈单峰型变化,夏季最高、冬季最低,夜间RE与土壤温度呈极显著正相关.全年NEE、RE和GEE分别为-668.40、932.55和-1600.95 g C·m^-2·a^-1,NEE占GEE的41.8%.与其他生态系统相比,毛竹林的固碳能力极强.     

黑曲霉3.795glaA基因及其5'调控区的克隆和序列分析

黑曲霉Ｔ２１是由黑曲霉３．７９５经诱变育种获得的糖化酶高产菌株,为阐明其高产的分子机制,由黑曲霉３．７９５克隆了糖化酶结构基因及其５′旁侧序列,并与黑曲霉Ｔ２１的相应序列进行了比较．由黑曲霉３．７９５菌丝体分离染色体ＤＮＡ,Ｓｏｕｔｈｅｒｎ杂交分析表明,糖化酶结构基因位于～２．５ｋｂ的ＥｃｏＲⅠ－ＥｃｏＲⅤ染色体ＤＮＡ片段上,在此ＥｃｏＲⅠ位点上游约１．０ｋｂ处有一ＳａｌⅠ位点．为构建糖化酶结构基因及其５′旁侧序列的基因组文库,该染色体ＤＮＡ分别用ＥｃｏＲⅠ＋ＥｃｏＲⅤ和ＥｃｏＲ＋ＳａｌⅠ消化,琼脂糖凝胶电泳分离并回收长度在１．０ｋｂ左右和２．５ｋｂ左右的ＤＮＡ片段,分别与ｐＵＣ１９载体连接后转化入Ｅ．ｃｏｌｉＤＨ５．用原位杂交方法筛选到了携带糖化酶基因编码区及其１５０５ｂｐ５′旁侧序列的阳性克隆．对克隆片段的ＤＮＡ序列进行了测定并与黑曲霉Ｔ２１的相应序列进行了比较,结果表明,在糖化酶基因编码区及其１５０ｂｐ３′非编码区内,未发现碱基差异,但在－３４０～－１５０５的５′上游区内发生了９个位置的碱基变化,包括缺失、插入和替换．这些结果表明,黑曲霉Ｔ２１与３．７９５的糖化酶产量的差异与其结构基因无关,但可能与其     

箬叶多糖的分离纯化及其理化性质的研究

采用分步提取的方式从中药箬叶中分离得到８种多糖组分：酸性杂多糖ＦＳ、ＦＥ、ＦⅠ,β－Ｄ－葡萄糖醛酸聚糖ＦⅡ和四种半纤维素多糖α－Ｄ－木聚糖ＦⅢ－ａ、ＦⅢ－ｂ、ＦⅣ－ａ及ＦⅣ－ｂ．紫外光谱、红外光谱、凝胶色谱、元素分析等结果表明８种箬叶多糖为纯品．并采用纸层析,气相色谱分析确定其单糖组成．采用高效凝胶渗透色谱ＧＰＣ法测定了４种箬叶多糖ＦＥ、ＦⅠ、ＦⅢ－ａ及ＦⅣ－ａ的重均分子量Ｍｗ、数均分子量Ｍｎ,均为大分子,分子量分布较窄,纯度较高．     

Facilitation by nurse shrubs of resprouting behavior in a post-fire shrubland in northern Patagonia,Argentina

Abstract. The nurse-plant syndrome is a widely recognized example of positive (facilitative) influences of plant species on the establishment and growth of other species. Most studies of the nurse-plant syndrome have been on species that reproduce mainly from seed rather than vegetatively. In this study, we experimentally compared the influences of two species of nurse shrubs, Schinus patagonicus and Berberis buxifolia, on the survival and growth of vegetatively reproducing herbaceous and woody plants in a post-fire shrubland in northern Patagonia, Argentina. The vegetation beneath shrubs was removed by clipping and, in a paired-sample design, one half of the canopy of each shrub was removed. We determined species richness, counted number of resprouts, and measured photon flux density and soil moisture beneath cut and uncut halves of each shrubs. Abundances of resprouts were several times greater beneath the uncut vs. the cut shrubs, as was the mean number of species. Thus, shrubs have a strong facilitating influence as measured by resprout densities and the number of species. Numbers of resprouts and of species were twice as high beneath Schinus as beneath Berberis, implying important differences in the facilitative effects of the two shrubs species. Microsites beneath Schinus were characterized by lower and more heterogeneous light levels but by greater soil moisture. Even though the reproductive mode in this post-fire shrubland is overwhelmingly vegetative, facilitation by nurse shrubs is important and differentially effective for different species of nurse shrubs.     

C-型咽侧体抑制素(AST-C)和促前胸腺激素释放激素(PTTH)基因在家蚕脑组织中的时空表达分析

【目的】咽侧体抑制素在昆虫体内具有重要的调控功能。本研究比较了家蚕Bombyx mori C-型咽侧体抑制素(allatostatin C,AST-C)与促前胸腺激素释放激素(prothoracicotropic hormone,PTTH)基因在不同发育阶段家蚕脑组织中转录表达的模式及其在脑组织的表达定位,以期为家蚕AST-C的功能研究提供重要的线索。【方法】利用脑组织芯片数据分析比较AST-C和PTTH基因在家蚕脑组织中的发育表达特征,RT-PCR验证其芯片数据,分析AST-C在不同发育阶段家蚕中枢神经系统中的表达模式,并用全组织包埋原位杂交技术对AST-C和PTTH在脑组织的表达进行定位。【结果】AST-C和PTTH在不同发育阶段家蚕脑组织中有相似的转录表达模式,且都在脑组织外侧一对神经分泌细胞中表达。【结论】AST-C可能与PTTH以相同的转录表达模式共同参与家蚕的变态发育调控。