Near-full-length REV3L appears to be a scarce maternal factor in Xenopus laevis eggs that changes qualitatively in early embryonic development

REV3 is the catalytic subunit of DNA polymerase ζ (pol ζ), which is responsible for the damage-induced mutagenesis that arises during error-prone translesion synthesis in eukaryotes. The related REV3L genes in human and mouse encode proteins of approximately 350 kDa, twice as large as yeast REV3, but full-length REV3L has not been identified in any vertebrate cell. We report that Xenopus laevis REV3L encodes a 352-kDa protein that has high overall amino acid sequence similarity to its mammalian counterparts, and, for the first time in a vertebrate species, we have detected putative REV3L polypeptides of 300 and 340 kDa in X. laevis oocytes. Only the 300-kDa form is stored in eggs, where its concentration of about 65 pM is much lower than those of other replication and repair proteins including the accessory pol ζ subunit REV7. In fertilized eggs, the levels of this polypeptide did not change until neurula; the larger 340-kDa form first appeared at stages after gastrula, suggesting a pattern of regulation during development. These observations indicate the existence of REV3L as a scarce protein, of approximately the full predicted size, whose level may impose severe constraints on the assembly of pol ζ in X. laevis.     

蓝藻基因工程应用研究进展

作为新的基因工程表达宿主,蓝藻以其独特的优势正逐渐引起人们的关注,自20世纪90年代以来,蓝藻已经形成了一套稳定的基因转化体系,20多年来已有30多种外源基因在蓝藻中表达成功。蓝藻表达系统将来有希望在制备重组药物、治理环境污染、农药生产等方面得到广泛应用。对蓝藻基因工程的发展及其在医药、环保、农业、生物传感器等方面的应用研究作一综述。最后分析了蓝藻基因工程发展的瓶颈表达效率低的问题,总结了研究者所作的努力：基因和剂型的选择、转录翻译元件的调控、宿主生理状态的调控等。     

伞房决明白粉病的初次报道(英文)

伞房决明是长江三角洲地区的园林绿化木本植物,在每年8月下旬至11月中旬会发生严重的白粉病,造成提前落叶,导致次年部分植株死亡。该病由Oidium cassiae-siameae引起。经过3年多的野外观察,未发现有性世代。初次报道伞房决明为Oidium cassiae-siameae白粉菌的新寄主。此真菌为中国大陆的初次记载。     

Overexpression of a NAC-domain protein promotes shoot branching in rice

For a better understanding of shoot branching in rice (Oryza sativa), a rice activation-tagging library was screened for mutations in tiller development. Here, an activation-tagging mutant Ostil1 (Oryza sativa tillering1) was characterized, which showed increased tillers, enlarged tiller angle and semidwarf phenotype. Flanking sequence was obtained by plasmid rescue. RNA-interfering and overexpression transgenic rice plants were produced using Agrobacterium-mediated transformation. The mutant phenotype was cosegregated with the reallocation of Ds element, and the flanking region of the reallocated Ds element was identified as part of the OsNAC2 gene. Northern analysis showed that expression of OsNAC2 was greatly induced in the mutant plants. Transgenic rice overexpressing the OsNAC2 resulted in recapture of the mutant phenotype, while downregulation of OsNAC2 in the Ostil1 mutant through RNA interfering (RNAi) complemented the mutant phenotype, confirming that the Ostil1 was caused by overexpression of OsNAC2. Overexpression of OsNAC2 regulates shoot branching in rice. Overexpression of OsNAC2 contributes tiller bud outgrowth, but does not affect tiller bud initiation. This suggests that OsNAC2 has potential utility for improving plant structure for higher light-use efficiency and higher yield potential in rice.     

Computational characterization of structural role of the non-active site mutation M36I of human immunodeficiency virus type 1 protease

A prominent characteristic of human immunodeficiency virus type 1 (HIV-1) is its high genetic variability, which generates diversity of the virus and often causes a serious problem of the emergence of drug-resistant mutants. Subtype B HIV-1 is dominant in advanced countries, and the mortality rate due to subtype B HIV-1 has been decreased during the past decade. In contrast, the number of patients with non-subtype B viruses is still increasing in developing countries. One of the reasons for the prevalence of non-subtype B viruses is lack of information about the biological and therapeutic differences between subtype B and non-subtype B viruses. M36I is the most frequently observed polymorphism in non-subtype B HIV-1 proteases. However, since the 36th residue is located at a non-active site of the protease and has no direct interaction with any ligands, the structural role of M36I remains unclear. Here, we performed molecular dynamics (MD) simulations of M36I protease in complex with nelfinavir and revealed the influence of the M36I mutation. The results show that M36I regulates the size of the binding cavity of the protease. The reason for the rare emergence of D30N variants in non-subtype B HIV-1 proteases was also clarified from our computational analysis.     

Differentiation of Bacillus anthracis, B. cereus, and B. thuringiensis by Using Pulsed-Field Gel Electrophoresis

A pulsed-field gel electrophoresis (PFGE) method was developed for discriminating Bacillus anthracis from B. cereus and B. thuringiensis. A worldwide collection of 25 B. anthracis isolates showed high-profile homology, and these isolates were unambiguously distinguished from B. cereus and B. thuringiensis isolates by cluster analysis of the whole-genome macrorestriction enzyme digestion patterns generated by NotI.     

Transport in rat vessel walls. II. Macromolecular leakage and focal spot size growth in rat arteries and veins

Transendothelial lipid transport into and spread in the subendothelial intima of large arteries, and subsequent lipid accumulation, appear to start plaque formation. We experimentally examine transendothelial horseradish peroxidase (HRP) transport in vessels that are usually, e.g., pulmonary artery (PA), or almost always, e.g., inferior vena cava (IVC), atherosclerosis resistant vs. disease prone, e.g., aorta, vessels. In these vessels, HRP traverses the endothelium at isolated, focal spots, rather than uniformly, for short circulation times. For femoral vein HRP introduction, PA spots have 30-s radii [ approximately 53.2 microm (SD 10.4); compare aorta: 54.6 microm (SD 8.75)] and grow quickly from 30 s to 1 min (40%, P<0.05) and more slowly afterward (P>0.05). This trend resembles the aorta, suggesting the PA has a similarly sparse intima. With carotid artery (CA) HRP introduction, the 30-s spot (132.86 +/- 37.32 microm) is far larger than the PAs, grows little ( approximately 28%, P<0.05) from 30 to 60 s, and is much flatter than the artery curves. Transverse electron microscopic sections after approximately 10 min HRP circulation show thin, intense staining immediately beneath both vessels' endothelia with an almost step change to diffuse staining beyond. This indicates the existence of a sparse, subendothelial intima, even when there is no internal elastic lamina (IVC). This motivates a simple model that translates growth rates into lower bounds for the flow through focal leaks. The model results and our earlier wall and medial hydraulic conductivity data explain these spot growth curves and point to differences in transport patterns that might be relevant in understanding the immunity of IVC to disease initiation.     

基于线粒体COⅠ基因序列探讨臂尾轮属的系统发生和几种轮虫的分类地位

通过对萼花臂尾轮虫、角突臂尾轮虫、壶状臂尾轮虫、十指臂尾轮虫、镰形臂尾轮虫、尾突臂尾轮虫和红臂尾轮虫等7种轮虫mtDNA COⅠ序列分析,并以透明囊足轮虫为外群,使用MEGA软件构建臂尾轮属轮虫系统发生树(ME树和NJ树)以探讨臂尾轮属的系统发生和该属中几个种类的分类地位.结果表明本研究所涉及的轮虫mtDNA COⅠ平均序列差异百分比为24%;在两个系统树中,淡水臂尾轮虫和海水臂尾轮虫均独立成枝;用两种方法得到的系统发生树均支持将十指臂尾轮虫作为一个独立的支系分离出来.壶状臂尾轮虫和红臂尾轮虫应属于不同的种;来自芜湖、墨西哥和美国的十指臂尾轮虫以及来自芜湖和澳大利亚的萼花臂尾轮虫应分别互为姐妹种.本研究还首次揭示了角突臂尾轮虫、尾突臂尾轮虫和镰状臂尾轮虫与其它臂尾轮虫间的系统关系.     

异翅负蝗配子发生过程中c-kit蛋白表达动态

应用免疫组织化学和生物统计分析相结合的方法,对异翅负蝗Atractomorp haheteroptera Bei Bienko配子发生过程中c-kit特异表达特点和动态进行研究。结果表明,(1)精子发生过程中,精原细胞、初级精母细胞、次级精母细胞和成熟精子中均有不同程度的c-kit蛋白表达,精巢末端还有较粗大的阳性颗粒分布;(2)卵子发生过程中,第1~6阶段卵母细胞中有不同程度的c-kit蛋白特异性表达,但随着卵黄发生的开始逐渐消失;(3)此外,滤泡细胞、输卵管和受精囊的腺细胞中有c-kit蛋白颗粒的存在;(4)从c-kit蛋白季节动态变化看,精子发生和卵子发生中的阳性表达都随着时间的延续出现下降的态势。因此,c-kit蛋白的特异性表达提示该蛋白参与配子发生过程的阶段性调控,具有重要的生理作用。     

Notch signaling is essential for ventricular chamber development

Ventricular chamber morphogenesis, first manifested by trabeculae formation, is crucial for cardiac function and embryonic viability and depends on cellular interactions between the endocardium and myocardium. We show that ventricular Notch1 activity is highest at presumptive trabecular endocardium. RBPJk and Notch1 mutants show impaired trabeculation and marker expression, attenuated EphrinB2, NRG1, and BMP10 expression and signaling, and decreased myocardial proliferation. Functional and molecular analyses show that Notch inhibition prevents EphrinB2 expression, and that EphrinB2 is a direct Notch target acting upstream of NRG1 in the ventricles. However, BMP10 levels are found to be independent of both EphrinB2 and NRG1 during trabeculation. Accordingly, exogenous BMP10 rescues the myocardial proliferative defect of in vitro-cultured RBPJk mutants, while exogenous NRG1 rescues differentiation in parallel. We suggest that during trabeculation Notch independently regulates cardiomyocyte proliferation and differentiation, two exquisitely balanced processes whose perturbation may result in congenital heart disease.