PIKK-dependent phosphorylation of Mre11 induces MRN complex inactivation by disassembly from chromatin

The role of Mre11 phosphorylation in the cellular response to DNA double-strand breaks (DSBs) is not well understood. Here, we show that phosphorylation of Mre11 at SQ/TQ motifs by PIKKs (PI3 Kinase-related Kinases) induces MRN (Mre11–Rad50–Nbs1) complex dissociation from chromatin by reducing Mre11 affinity for DNA. Whereas phosphorylation of Mre11 at these residues is not required for DSB-induced ATM (Ataxia-Telangiectasia mutated) activation, abrogation of Mre11 dephosphorylation impairs ATM signaling. Our study provides a functional characterization of the DNA damage-induced Mre11 phosphorylation, and suggests that MRN inactivation participates in the down-regulation of damage signaling during checkpoint recovery following DSB repair.     

KRAB型锌指蛋白在高等脊椎动物胚胎发育和肿瘤发生、发展中的调控功能

KRAB型锌指蛋白(KRAB-ZFPs)最早出现于四足类脊椎动物, 且进化非常迅速, 是人类基因组编码的最大转录因子家族。尽管当前对此家族蛋白发挥调控功能的分子机制已有较为深入的研究, 但关于此家族蛋白所具备的高等脊椎动物特有的调控功能目前尚无全面系统的认识。文章对KRAB型锌指蛋白在高等脊椎动物的胚胎发育及肿瘤发生、发展中发挥的调控功能进行综述, 以期丰富对该家族蛋白在不同生理、病理过程中调控功能的认识, 为今后更深入的理论和应用研究打下坚实基础。     

Downregulation of CD2-associated protein impaired the physiological functions of podocytes

Emerging evidences show that CD2-associated protein (CD2AP) is involved in podocyte injury and the pathogenesis of proteinuria. However, the exact molecular mechanism by which CD2AP exerts its biological function is elusive. We knocked down CD2AP gene by target siRNA in conditionally immortalized mouse podocytes, which showed lowered cell adhesion and spreading ability (P < 0.05). At the same time, cell cycle was arrested in G2/M phase (P < 0.05), and pathologic nuclear division could easily be seen in CD2AP siRNA-transfected podocytes. The proliferation of podocytes were also inhibited significantly by CD2AP siRNA transfection (P < 0.05). Further study revealed disordered distributions of F-actin, as well as lowered nephrin expression and phosphorylation in podocytes. These data suggest that CD2AP may play a crucial role in maintaining the normal function of podocytes and lowered CD2AP causes podocyte injury by disrupting the cytoskeleton and disturbing the nephrin-CD2AP signaling pathway.     

人SATB1基 5'上游序列的转录激活功能分析

在对人SATB1基因进行生物信息学分析的基础上,采用PCR技术,扩增人基因组DNA中SATB1基因5'上游序列的-2955～-9片段,构建了3个分别由SATB1基因5'上游-2955～-9,-1727～-9和-760～-9序列片段驱动的报告载体-pGL3-SP2946-luc,pGL3-SP1718-luc和pGL3-SP751-luc,分别瞬时转染Jurkat T,K562,U937和HeLa细胞,通过测定荧光素酶的表达活性,观察SATB1基因5'上游序列片段3个删除突变体在不同细胞内活性的差异.结果显示,SATB1上游序列-2955/-9在4种细胞中的转录激活能力为U937>Jurkat T>K562,在HeLa细胞中基本无激活,提示SATB1的转录激活可能具有一定的细胞类型特异性.3种5'删除突变体转录激活性由大至小顺序为-760/-9>-2955/-9>-1727/-9,提示SATB1的核心启动子可能存在于其5'上游序列的-760至-9 bp区域中.     

人新基因hbrp的染色体定位及其对TPK活性的抑制作用（简报）

hbrp(Human BSP-Related Protein)是我们实验室最近在睾丸组织中克隆的一个人与BSP（bovine seminal plasma)蛋白相关的新基因。为了将有关该新基因信息与现有人类基因组转录图相整合,我们应用荧光原位杂交(fluorescent in situ hybridizationFISH)法进行了该基因的人染色体基因定位,结果成功地将hbrp基因定位在人19号染色体长臂1区3带上。hbrp基因是在对BSP蛋白功能的研究过程中发现并克隆的,其同源性分析发现,与其序列最相近     

烯效唑对青钱柳试管苗生长及生理特性的影响

在含0.00(CK)、0.01、0.05、0.10和1.00 mg·L-1烯效唑的WPM培养基上继代培养120 d后,对青钱柳[Cyclocarya paliurus (Batal.)Iljinskaja]试管苗的部分生长及生理指标的变化进行了比较研究.结果显示:不同质量浓度烯效唑对青钱柳试管苗的生长及生理指标有不同的影响效应.总体上,随培养基中烯效唑质量浓度的提高,青钱柳试管苗的苗高、叶片数和可溶性蛋白质含量逐渐降低,可溶性糖与可溶性蛋白质含量的比值、SOD和POD活性逐渐提高;在培养基中添加0.01、0.05和0.10 mg·L-1烯效唑对青钱柳试管苗的成活率无显著影响,却可使试管苗的单株鲜质量增加量、叶绿素含量和可溶性糖含量均高于对照;在培养基中添加1.00 mg·L-1烯效唑能显著或极显著降低试管苗的成活率、单株鲜质量增加量、分化芽数、苗高、叶片数以及叶绿素含量、可溶性糖含量和可溶性蛋白质含量,并使苗茎出现异常增粗和矮化.而在含0.10 mg·L-1烯效唑的培养基上,虽然试管苗的苗高、分化芽数和叶片数分别较对照降低了28.03%、9.70%和12.37%,但试管苗的单株鲜质量增加量、叶绿素含量、可溶性糖含量、可溶性糖与可溶性蛋白质含量的比值、 SOD和POD活性分别较对照提高了99.39%、 14.00%、 5.00%、115.43%、129.77%和33.79%.研究结果表明,在培养基中添加0.10 mg·L-1烯效唑可有效改善青钱柳试管苗的生长和生理特性,有效控制苗高和叶片数,促进苗茎的增粗,有助于增强试管苗的抗逆能力.     

秦岭植物区系一新记录科——茶茱萸科

首次报道了茶茱萸科(Icacinaceae)假柴龙树属(Nothapodytes Bl.)马比木[Nothapodytes pittosporoides (Oliv.) Sleum.]在秦岭南坡(陕西省山阳县)的分布,为秦岭植物区系增加一新记录科--茶茱萸科     

Synergetic effect of pH and biochemical components on bacterial diversity during mesophilic anaerobic fermentation of biomass-origin waste

Aims: To investigate the synergetic effect of pH and biochemical components on bacterial community structure during mesophilic anaerobic degradation of solid wastes with different origins, and under acidic or neutral conditions. Methods and Results: The bacterial community in 16 samples of solid wastes with different biochemical compositions and origins was evaluated during mesophilic anaerobic degradation at acidic and neutral pH. Denaturing gradient gel electrophoresis (DGGE) and single‐strand conformation polymorphism (SSCP) were used to compare the communities. Multivariate analysis of the DGGE and SSCP results revealed that most of the dominant microbes were dependent on the content of easily degradable carbohydrates in the samples. Furthermore, the dominant microbes were divided into two types, those that preferred an acid environment and those that preferred a neutral environment. A shift in pH was found to change their preference for medium substrates. Although most of the substrates with similar origin and biochemical composition had similar microbial diversity during fermentation, some microbes were found only in substrates with specific origins. For example, two microbes were only found in substrate that contained lignocellulose and animal protein without starch. These microbes were related to micro‐organisms that are found in swine manure, as well as in other intestinal or oral niches. In addition, the distribution of fermentation products was less sensitive to the changes in pH and biochemical components than the microbial community. Conclusions: Bacterial diversity during anaerobic degradation of organic wastes was affected by both pH and biochemical components; however, pH exerted a greater effect. Significance and Impact of the Study: The results of this study reveal that control of pH may be an effective method to produce a stable bacterial community and relatively similar product distribution during anaerobic digestion of waste, regardless of variation in the waste feedstocks.     

A Genome-wide Functional Characterization of Arabidopsis Regulatory Calcium Sensors in Pollen Tubes

Calcium, an ubiquitous second messenger, plays an essential and versatile role in cellular signaling. The diverse function of calcium signals is achieved by an excess of calcium sensors. Plants possess large numbers of calcium sensors, most of which have not been functionally characterized. To identify physiologically relevant calcium sensors in a specific cell type, we conducted a genome-wide functional survey in pollen tubes, for which spatiotemporal calcium signals are well-characterized and required for polarized tip growth. Pollen-specific members of calmodulin (CaM), CaM-like (CML), calcium-dependent protein kinase (CDPK) and calcineurin B-like protein (CBL) families were tagged with green fluorescence protein (GFP) and their localization patterns and overexpression phenotypes were characterized in tobacco pollen tubes. We found that several fusion proteins showed distinct overexpression phenotypes and subcellular localization patterns. CDPK24-GFP was localized to the vegetative nucleus and the generative cell/sperms. CDPK32-GFP caused severe growth depolarization. CBL2-GFP and CBL3-GFP exhibited dynamic patterns of subcellular localization, including several endomembrane compartments, the apical plasma membrane (PM), and cytoskeleton-like structures in pollen tubes. Their overexpression also inhibited pollen tube elongation and induced growth depolarization. These putative calcium sensors are excellent candidates for the calcium sensors responsible for the regulation of calcium homeostasis and calcium-dependent tip growth and growth oscillation in pollen tubes.