深黄被孢霉△^6—脂肪酸脱氢酶基因在转基因烟草中的表达

γ—亚麻酸(GLA)是人体和动物饮食中具有营养作用的重要的多烯不饱和脂肪酸,在大多数油料作物种子中不含有GLA,而只含有其前体物亚油酸,只有少数油料植物种子中含有GLA,如夜来香(Oenothera spp),琉璃苣(Borago officinalis)等。△^6—脂肪酸脱氢酶可将亚油酸转化为γ—亚麻酸,为了能够在传统的油料作物种子中产生GLA,我们将从深黄被孢霉中克隆的△^6—脂肪酸脱氢酶基因,与植物表达载体pGA643连接,构建了重组质粒pGAM—ICL6,将其通过农杆菌介导法,导入模式植物烟草中。经PCR和Southern杂交分析表明该基因已导入并整合到烟草的基因组中,Northern杂交结果表明该基因在转基因烟草的mRNA水平上获得表达。对转基因植株进行脂肪酸分析,结果显示,GLA和十八碳四烯酸(OTA)分别占总脂肪酸含量的19．7％和3．5％。     

含铬重组液激活部分缺失金属原子簇的钼铁蛋白的研究

棕色固氮菌（Ａｚｏｔｏｂａｃｔｅｒ ｖｉｎｅｌａｎｄｉｉ）固氮酶钼铁蛋白经邻菲口罗啉和Ｏ２ 处理后,变为部分缺失ＦｅＭｏｃｏ 和Ｐ－ｃｌｕｓｔｅｒ的失活蛋白。与由Ｋ２ＣｒＯ４、高柠檬酸铁、Ｎａ２Ｓ和二硫苏糖醇组成的重组液保温后,处理蛋白对乙炔和质子还原的活性都得以显著恢复;然而,它的吸收光谱和圆二色谱虽有明显恢复,但仍与还原钼铁蛋白有所不同。这表明,激活蛋白中也许存在功能与钼铁蛋白相似,而结构则有所差异的含铬（ＣｒＦｅ）蛋白     

THE ULTRASTRUCTURE OF THE ENAMEL IN THE GIANT PANDA OF PLEISTOCENE

<正> Enamel ultrastructures in the molar teeth of the giant panda, including Ailuropoda microta of the Early Pleistocene, Ailuropoda melanoleuca bacont of the Middle and Late Pleistocene and a living form, Ailuropoda rnelanoleuca, have been investigated by scanning electron microscopy. Transverse and longitudinal sections of enamel were made in order co evaluate shape, size and arrangement of the prisms. The sections were etched then with 0.074 M H_3PO_4 for 30-60 sec. Our investigations have shown certain features of the enamel which allow us to recognize differences among Ailuropoda on the basis of examination of large areas of the enamel. The results are summarized below.     

microRNA在小鼠乳腺不同发育时期差异表达谱及作用

microRNA是一类大小约22个核苷酸的非编码RNA分子,是一种广泛存在的对基因表达进行微调的分子。microRNA可以通过与靶基因mRNA的特定位点结合,抑制该蛋白的合成或诱导该mRNA的降解,从而参与基因的表达调控。一般来源于染色体的非编码区域,由大约70个核苷酸大小的可形成发夹结构的前体经Dicer酶加工而来。这类小RNA在表达上具有组织和时间的特异性,是调节其他功能基因表达的重要调控分子,在生物的生长发育过程中发挥着重要作用。因此,虽然microRNA的研究仅有很短的历史,但已成为基因表达调控研究的热点领域。以中国昆明小鼠不同发育时期的乳腺组织为实验材料,应用芯片技术及荧光定量PCR技术,分析发育不同时期的乳腺组织microRNA差异表达图谱。本文研究发现microRNA在乳腺不同的发育时期表达图谱不同;与青春期、退化期比较,妊娠期、哺乳期有十余种microRNAs表达上调,20余种microRNAs表达下调;microRNAs在乳腺发育和泌乳周期中发挥重要的作用。     

Biodiesel production from high acid value waste frying oil catalyzed by superacid heteropolyacid

Transesterification of waste cooking oil with high acid value and high water contents using heteropolyacid H3PW12O40 x 6H2O (PW12) as catalyst was investigated. The hexahydrate form of PW(12) was found to be the most promising catalyst which exhibited highest ester yield 87% for transesterification of waste cooking oil and ester yield 97% for esterification of long-chain palmitic acid, respectively. The PW12 acid catalyst shows higher activity under the optimized reaction conditions compared with conventional homogeneous catalyst sulfuric acid, and can easily be separated from the products by distillation of the excess methanol and can be reused more times. The most important feature of this catalyst is that the catalytic activity is not affected by the content of free fatty acids (FFAs) and the content of water in the waste cooking oil and the transesterification can occur at a lower temperature (65 degrees C), a lower methanol oil ratio (70:1) and be finished within a shorter time. The results illustrate that PW12 acid is an excellent water-tolerant and environmentally benign acid catalyst for production of biodiesel from waste cooking oil.     

Solid Phase Synthesis of Phosphopeptides Incorporating 2,2-Dimethyloxazolidine Pseudoproline Analogs: Evidence for <Emphasis Type="Italic">trans</Emphasis> Leu-Pro Peptide Bonds in Stat3 Inhibitors

To answer the question of whether the conformation of the Leu-Pro bond is cis or trans in Ac-pTyr-Leu-Pro-Gln-Thr-Val-NH₂ when complexed with the SH2 domain of Stat3, we substituted 2,2-dimethyloxazolidines derived from serine (Ser(Ψ^Me,Mepro)) and threonine (Thr(Ψ^Me,Mepro)) for proline. The 2,2-dimethyloxazolidine and 2,2-dimethylthiazolidine pseudoproline (ΨPro) analogs induce predominantly cis Xxx-ΨPro peptide bonds. As these ΨPro analogs are acid-labile, the phosphopeptides were synthesized using Fmoc-based SPPS using unprotected phosphotyrosine and 4-hydroxybenzoate as the linker that allowed release from the support by alkaline ammonolysis, conditions that kept the oxazolidine rings intact. Incorporation of Ser(Ψ^Me,Mepro) resulted in 69% cis Leu-ΨPro bond content in aqueous solution whereas that for Thr(Ψ^Me,Mepro) analog was 63%. Affinities for Stat3 were 3–5 fold lower than the lead compound and were inversely correlated with cis content. Thus we conclude that the Leu-Pro peptide bond is trans when the peptide is bound to Stat3.