用聚合酶链反应扩增出猪源大肠杆菌编码ST前体（pro-ST）和Lt的B亚单位（LTB）成熟多肽的序列，再通过套式PcR将pro-ST编码序列3'端和LTB编码序列5’端融合，并置于同一词读框内，得到SL和LTB的融合基因，将此序列克隆到pGEM-T质粒中，序列分析后，亚克隆到表达载体pOE30中，在大肠杆菌细胞中得到表达，表达的融合蛋白同时具有田和LTB的抗原性，且无ST和LT的生物毒性。

MicroRNAs (miRNAs) are present in both plant and animal kingdoms and represents a growing family of non-coding RNAs. These tiny RNAs act as small guides and direct negative regulations usually in the process of development through sequence complementarity to target mRNAs. Although a large number of miRNAs have been identi?ed from various animals, so far plant miRNA studies have focused mainly on Arabidopsis. Here we describe the identification of 20 miRNAs from a rice cDNA library. All the miRNAs were presumably processed from precursors with stem±loop structures and were positively detected in rice cells from at least one tissue, some of which showed tissue-specific expression. Twenty-three unique rice genes were identified to be feasible targets for seven rice miRNAs, including four members of Scarecrow-like transcription factor, the targets of miR-39 that had been characterized in Arabidopsis. Lacking long complementarity, the regulatory targets of 13 miRNAs remain to be further investigated. A possible mechanism of translational repressor for plant miRNAs that lack perfect complementarity to target mRNAs is discussed.

采用特异性引物自贵州黑羽乌骨鸡胃部组织克隆了Ghrelin的基因，基因全长12330bp，含有4个外显子，3个内含子。采用RT—PcR技术，获得了Ghrelin cDNA版式段（563bp），Il序列分析推测，通过可变剪切可产生两mRNA，cDNA编码区与基因组中的编码区完全一致。黑羽乌骨鸡Ghrelin基因与已知鸡种比较有13～18个碱基不同，相似性为99.1～99/3%，但其氨基酸序列完全一样，表明禽类 Ghrelin。多肽高度保守。将其 Ghrehn编码区亚克隆到原II核表达载44kpTYBll中，经序列测定碱基序列正确，获得重组质：pTYBll/G。在IPTG的诱导下，重组质粒在大肠杆菌ER2566中获得表达。当ODm=0.5，IPTG浓度1mmol/L，诱导5小l时的表达量最高，融合蛋白占细胞总蛋白40%。采用几质结合的预装柱对表达产物进行l纯化，产率约为5 mg/L培养液。

【目的】紫杉醇是重要的抗癌药物，主要从罗汉松等植物中提取，为了保护罗汉松等种质资源，本文从罗汉松植株中分离产紫杉醇内生真菌，并对内生真菌所产紫杉醇的抗肿瘤活性进行了分析。【方法】采用组织块法自罗汉松的根、茎、叶等组织中分离内生真菌：通过四唑蓝（Methvl ThlazolvlTetrazollum，MTT）比色法筛选有抗肿瘤活性的内生真菌菌株，通过薄层层析（Thln Laver chro-matography，TLc）和高效液相色谱（H1gh Performance L1quld chromatography，HPLc）对内生真菌所产活性物质进行鉴定：采用抽提法抽提内生真菌所产紫杉醇，应用vero细胞对抽提的紫杉醇的活性进行了分析。【结果】从罗汉松属（Podocrapus）植物中分离到155株内生真菌，其中28株内生真菌具有较高的抑癌活性。将其中一株菌株A2命名为EPTP-1，经形态学和分子分类学分析鉴定为烟曲霉（Aspergillus fumigatus）菌株EPTP-1中抽提的紫杉醇5.553ug/L～555.3ug/L作用24h表现出明显的致细胞凋亡作用。菌株EPTP-1发酵5天时紫杉醇的产率为0.5578±0.0294mg/L。【结论】从罗汉松中分离到了一株产紫杉醇内生真菌EPTP-1，可作为紫杉醇类药物工业化生产的候选菌株。

以两对合成的寡核苷酸引物，通过聚合酶链式反应，检测158份猪和牛腹泻粪便分离物，从8份猪源和3份牛源分离物中扩增出大肠杆菌志贺样毒素基因片段，其生化试验符合大肠杆菌特征，经v目。细胞检测均产生志贺样毒素，血清学试验证实分属不同的血清型，与志贺样毒素大肠杆菌血清型范围相符。