鲫鱼视网膜谷氨酸受体和GABA受体在爪蟾卵母细胞中的表达

我们以两栖类卵母细胞为功能表达系统,通过注射鲫鱼（Ｃａｒａｓｓｉｕｓｃａｒａｓｓｉｕｓ）视网膜ｍＲＮＡ,利用电压箝及药物灌流手段,系统地研究了鲫鱼视网膜内氨基酸受体的类型和特征,结果如下：（１）Ｇｌｕ受体：ＫＡ可以诱发明显的去极化电流,而且Ｄｉａｚｏｘｉｄｅ能增强ＫＡ诱导的反应,这提示鲫鱼视网膜内某些Ｃｌｕ受体是ＡＭＰＡ选择性亚型（ＡＭＰＡ－ｐｒｅｆｅｒｒｉｎｇｓｕｂｔｙｐｅ）。（２）ＣＡＢＡ受体：ＧＡＢＡ能诱发一个快速、光滑的内向电流,绝大部分对ＧＡＢＡ的反应可被ｂｉｃｕｃｕｌｌｉｎｅ所压抑,而ＧＡＢＡ＿Ｂ受体的激动剂ｂａｃｌｏｆｅｎ则无任何作用,这提示,鲫鱼视网膜内大部分是ＧＡＢＡ＿Ａ受体。     

Plant mRNA 3′-end formation

Our understanding of how the 3 ends of mRNAs are formed in plants is rudimentary compared to what we know about this process in other eukaryotes. The salient features of plant pre-mRNAs that signal cleavage and polyadenylation remain obscure, and the biochemical mechanism is as yet wholly uncharacterised. Nevertheless, despite the lack of universally conserved cis-acting motifs, a common underlying architecture is emerging from functional analyses of plant poly(A) signals, allowing meaningful comparison with components of poly(A) signals in other eukaryotes. A plant poly(A) signal consists of one or more near-upstream elements (NUE), each directing processing at a poly(A) site a short distance downstream of it, and an extensive far-upstream element (FUE) that enhances processing efficiency at all sites. By analogy with other systems, a model for a plant 3-end processing complex can be proposed. Plant poly(A) polymerases have been isolated and partially characterised. These, together with hints that some processing factors are conserved in different organisms, opens promising avenues toward initial characterisation of the trans-acting factors involved in 3-end formation of mRNAs in higher plants.     

Isolation and cDNA cloning of an Em-like protein from mung bean (Vigna radiata) axes

Until now no 'early-methionine-labelled' (Em) proteins have been reported in the Fabaceae. To check whether a previously isolated low-molecular mass albumin from dry mung bean embryonic axes possibly corresponded to an Em-like protein, the protein was purified, sequenced and its cDNA clone isolated and characterized. N-terminal sequencing of cyanogen bromide cleavage products of the protein revealed homology with previously described Em-like proteins from other species. Analysis of cDNA clones encoding the mung bean Em protein revealed the presence of two classes of Em proteins and confirmed their homology to the previously characterized Em-like proteins. In vivo labelling and northern blot analysis further demonstrated that the mung bean protein is synthesized during early germination of the axes and that abscisic acid (ABA) extends its synthesis. It appears, therefore, that legumes also contain maturation-specific, ABA-responsive Em-like proteins.     

大鼠脊髓内生长抑素mRNA原位杂交的研究

采用地高辛标记生长抑素反意ＲＮＡ探针经原位杂交和显色后,光学显微镜下观察生长抑素ｍＲＮＡ在大鼠脊髓内的定位。结果显示：脊髓内含有大量呈紫蓝色的生长抑素ｍＲＮＡ阳性神经细胞,岍性磷酸酶反应产生     

汉防己甲素及克矽平对矽肺大鼠Ⅰ型和Ⅲ型胶原mRNA的影响

汉防己甲素（汉甲）及克矽平（Ｐｏｌｙｖｉｎｙｌｐｙｒｉｄｉｎｅ－Ｎ－Ｏｘｉｄｅ,ＰＶＮＯ）是目前较为有效的抑制矽肺纤维化的药物。本文研究了其对胶原ｍＲＮＡ水平的影响．斑点杂交实验表明大鼠接尘６０天和１２０天后α１（Ⅰ）及α１（Ⅲ）ｍＲＮＡ水平明显上升,经汉甲或克矽平治疗１个月或３个月后,胶原ｍＲＮＡ水平明显下降。原位杂交结果表明胶原ｍＲ－ＮＡ银颗粒与细胞性结节和增厚的肺泡壁的成纤维细胞分布重合。汉甲或克矽平治疗后银颗粒数下降。提示汉甲及克矽平对矽肺进程中的胶原基因表达增强有抑制作用。