慢病毒载体介导IκB激酶-α(IKKα)基因RNA干扰转基因小鼠的制备

IκB激酶-α(IKKα)的功能与淋巴形成和乳腺发育相关,在乳腺肿瘤中观察到IKKα蛋白的过量表达.应用小鼠受精卵卵周隙注射慢病毒载体的方式,建立IKKα基因RNAi转基因小鼠模型,为在体内研究IKKα基因的生物学功能及其与肿瘤发生的关系创造条件.实验构建了针对IKKα基因RNAi(剔降)的慢病毒载体,并将载体导入小鼠受精卵卵周隙,获得携带该载体的转基因小鼠模型,经PCR鉴定首建鼠阳性率为15%.转基因小鼠外周血细胞IKKαmRNA表达量明显降低.初步表型观察分析,IKKα基因RNAi小鼠发育正常,进一步的分析工作正在进行中.     

乳腺癌中雌激素受体α表达水平调节的分子机制

雌激素受体α(ERα)在乳腺癌的发生发展中扮演重要角色,因而ERα成为乳腺癌治疗的分子靶标。ERα的表达水平在乳腺癌患者中差异较大,即使同一患者,在乳腺癌的不同阶段也可能有很大的差别。乳腺癌内分泌治疗的疗效以及预后都与ERα表达水平密切相关。影响ERα表达水平的分子机制复杂,众多调节分子在染色质、转录、转录后、翻译和翻译后等水平参与ERα表达水平的调节。在染色质和转录水平,许多分子通过直接或间接地与ERα启动子的相互作用改变ERα的转录;在转录后/翻译水平,一些microRNA通过诱导ERαmRNA的降解和/或抑制其翻译降低ERα的水平;在翻译后水平,许多分子通过泛素-蛋白酶体途径调节ERα蛋白水平。文章从不同水平,对这些调节分子的调节机制进行简要综述。     

3-Hydroxyflavone inhibits endogenous Aurora B and induces growth inhibition of cancer cell line

The Aurora kinases play a critical role in mitosis and have been suggested as promising targets for cancer therapy due to their frequent overexpression in a variety of tumors. Compared with established inhibitors of cell division such as the anti-tubulins, novel agents target mitotic enzymes and show similar efficacy but with fewer side effects. Several small-molecule inhibitors of Aurora kinases have been developed as anticancer agents, some of which have progressed to early clinical evaluation. Here we identified 3-hydroxyflavone as a novel Aurora B inhibitor through high throughput screening. 3-Hydroxyflavone showed potent inhibition to Aurora B with the IC₅₀ on a nanomolar basis in the enzyme-based kinase activity assay. In the cell-based western blotting analysis, 3-hydroxyflavone dramatically decreased the phosphorylation level of Histone H3 on the site of serine 10, demonstrating the potent endogenous Aurora B activity inhibition in cell level. The followed cell image analysis provided the consist result. To make it clear whether 3-hydroxyflavone inhibited Aurora B by direct binding or not, SPR analysis was carried out to measure the affinity of interaction between Aurora B protein and 3-hydroxyflavone and the result proved the binding with high affinity. Usually Aurora activity suppression induced cancer cell proliferation inhibition. Colony formation and cell viability with/without treatment of 3-hydroxyflavone were measured using CCK-8. The growth suppression under 3-hydroxyflavone present and the growth recovery after being released gave strong evidence that presence of 3-hydroxyflavone efficiently inhibited the fast growth of cancer cells.     

Embryo production and possible species preservation by nuclear transfer of somatic cells isolated from bovine semen

Somatic cells in semen are a potential source of nuclei for nuclear transfer to produce genetically identical animals; this is especially important when an animal has died and the only viable genetic material available is frozen semen. Usefulness of somatic cells obtained from fresh (cultured) and frozen (isolated, not cultured) bovine semen for nuclear transfer was evaluated. Twelve ejaculates were collected from nine bulls representing three breeds: Charolais, Brahman, and crossbred Rodeo bull. All samples were processed immediately and cell growth was obtained from seven of the twelve ejaculates (58.3%). Cells from three bulls (with the best growth rates) were evaluated by optical microscopy and used in cloning experiments. In culture, these cells exhibited classic epithelial morphology and expressed cytokeratin and vimentin, indicating they were of epithelial origin. When cells from the three bulls were used as donor cells, 15.9% (18/113), 34.5% (29/84), and 14.4% (13/90) of the fused embryos developed into blastocysts, respectively. Of the blastocyst stage embryos, 38.9% (7/18), 72.4% (21/29), and 61.5% (8/13) hatched, respectively. Somatic cells isolated (not cultured) from frozen bovine semen were also used in the cloning experiments. Although cleavage occurred, no compact morulae or blastocysts were obtained. In conclusion, epithelial cell growth was obtained from fresh bovine ejaculates with relatively high efficiency. Somatic cells from semen can be used as nucleus donors to produce cloned blastocyst-stage embryos.     

Birth intervention and non-maternal infant-handling during parturition in a nonhuman primate

Direct intervention in infant delivery by non-parturient individuals is a rare phenomenon in nonhuman primates. In contrast, birth assistance by other individuals, or the practice of midwifery, is universal among human societies and generally believed to be a behavior unique to our species. It has been proposed that the enlarged head of the human fetus and the relatively narrow birth canal constrained by bipedalism has made human parturition more difficult than in nonhuman primates, and these anatomic challenges have led to the rotation of the fetus in the birth canal and an occiput anterior (i.e., backward-facing) orientation of emergence. These characteristics have hindered the mother’s ability to self-assist the delivery of the infant, therefore necessitating assistance by other individuals or midwives for successful birth. Here we report the first high-definition video recordings of birth intervention behavior in a wild nonhuman primate, the white-headed langur (Trachypithecus leucocephalus). We observed that while a primiparous female gave birth to an infant in an occiput posterior (i.e., forward-facing) orientation, a multiparous female intervened in the delivery by manually pulling the infant out of the birth canal and cared for it in the following hours. Our finding shows extensive social interactions throughout parturition, and presents an unequivocal case of non-maternal intervention with infant birth in a nonhuman primate.     

Anti-convulsant Effect and Mechanism of Astragalus mongholicus Extract In Vitro and In Vivo: Protection Against Oxidative Damage and Mitochondrial Dysfunction

Astragalus mongholicus (AM) is a traditional medicinal herb used as a neuroprotective agent for its anxiolytic, antidepressant, antiamnestic, and antiaggresive effects. However, the mechanisms underlying its anti-convulsant properties are not well studied. In the present study, we examined the anticonvulsant effects on pentylenetetrazol (PTZ)-induced seizures in mice and the possible mechanisms of protection against oxidative damage and mitochondrial dysfunction in vitro. The behavioral studies showed that the root extract of AM had powerful anticonvulsant effects against seizures induced by PTZ and the biochemical studies showed that root extract of AM inhibited PTZ-induced increase in lipid peroxidation, protein oxidation and reactive oxygen species, and enhanced mitochondrial function. Electron spin resonance spectroscopy studies demonstrated that the extracts from the root and aerial parts of AM possess potent effects on scavenging hydroxyl and lipid free radicals. We found that AM extract significantly protected malondialdehyde-induced oxidative damage by ameliorating activities of the mitochondrial complexes I, II, malate dehydrogenase and mitochondrial membrane potential. These data suggest that the anti-convulsant effects of AM extract may be mediated by its protective actions against oxidative damage and amelioration of mitochondrial dysfunction.     

Two cotton fiber‐associated glycosyltransferases,GhGT43A1 and GhGT43C1, function in hemicellulose glucuronoxylan biosynthesis during plant development

Xylan is the major hemicellulosic constituent in dicot secondary cell walls. Cell wall composition of cotton fiber changes dynamically throughout development. Not only the amounts but also the molecular sizes of the hemicellulosic polysaccharides show substantial changes during cotton fiber development. However, none of the genes encoding glycosyltransferases (GTs) responsible for synthesizing xylan have been isolated and characterized in cotton fiber. In this study, we applied a bioinformatics approach and identified two putative GTs from cotton, designated GhGT43A1 and GhGT43C1, which belong to the CAZy GT43 family and are closely related to Arabidopsis IRX9 and IRX14, respectively. We show that GhGT43A1 is highly and preferentially expressed in 15 and 20 days post‐anthesis (dpa) cotton fiber, whereas GhGT43C1 is ubiquitously expressed in most organs, with especially high expression in 15 dpa fiber and hypocotyl. Complementation analysis demonstrates that GhG43A1 and GhGT43C1 are orthologs of Arabidopsis IRX9 and IRX14, respectively. Furthermore, we show that overexpression of GhGT43A1 or GhGT43C1 in Arabidopsis results in increased xylan content. We also show that overexpression of GhGT43A1 or GhGT43C1 leads to more cellulose deposition. These findings suggest that GhGT43A1 and GhGT43C1 likely participate in xylan synthesis during fiber development.     

微生物抗重金属的生理机制

虽然环境中高浓度的重金属对微生物有毒害作用,但一些微生物表现出抗重金属的特性,在细胞结构、生理代谢和遗传水平方面形成了不同的抗性机制.主要从生物吸附、胞外沉淀、生物转化、生物累积和外排作用等5个方面阐述了微生物对重金属抗性的生理和分子机制,为重金属污染环境的生物修复提供理论依据.