Structural basis for molecular recognition and presentation of histone H3 by WDR5

Histone methylation at specific lysine residues brings about various downstream events that are mediated by different effector proteins. The WD40 domain of WDR5 represents a new class of histone methyl-lysine recognition domains that is important for recruiting H3K4 methyltransferases to K4-dimethylated histone H3 tail as well as for global and gene-specific K4 trimethylation. Here we report the crystal structures of full-length WDR5, WDR5Delta23 and its complexes with unmodified, mono-, di- and trimethylated histone H3K4 peptides. The structures reveal that WDR5 is able to bind all of these histone H3 peptides, but only H3K4me2 peptide forms extra interactions with WDR5 by use of both water-mediated hydrogen bonding and the altered hydrophilicity of the modified lysine 4. We propose a mechanism for the involvement of WDR5 in binding and presenting histone H3K4 for further methylation as a component of MLL complexes.     

单叶蔓荆子化学成分研究初报

对产于福建（莆田平海）海滨沙地的单叶蔓荆子的一般化学成分进行了分析,为开发利用福建沿海沙滩单叶蔓荆资源提供科学依据.结果表明：福建产单叶蔓荆子的水分、脂肪、粗蛋白及灰分含量分别为10.8%、4.05%、5.9%和3.36%,符合2005年版《中国药典》要求.其重金属元素含量Pb＜0.01 μg/g、As＜0.1 μg/g、Hg＜0.01 μg/g、Cd为0.02 μg/g、Cu为6 μg/ g,达到《药用植物及制剂进出口绿色行业标准》（WM2-2001）中重金属元素限量要求.蔓荆子生药材17种氨基酸总量为3.51%（mg/100 mg）,此外还检出微量γ-氨基丁酸（GABA,2.203 mg/100 g）.蔓荆子生药材中含有10种脂肪酸,以不饱和脂肪酸（69.6%）为主,主要成分包括棕榈酸（6.6%）、硬脂酸（5.4%）、油酸（22.0%）、亚油酸（46.0）及少量亚麻酸（0.8%）.     

Sec13 safeguards the integrity of the endoplasmic reticulum and organogenesis of the digestive system in zebrafish

The Sec13-Sec31 heterotetramer serves as the outer coat in the COPII complex, which mediates protein trafficking from the endoplasmic reticulum (ER) to the Golgi apparatus. Although it has been studied in depth in yeast and cultured cells, the role of COPII in organogenesis in a multicellular organism has not. We report here that a zebrafish sec13(sq198) mutant, which exhibits a phenotype of hypoplastic digestive organs, has a mutation in the sec13 gene. The mutant gene encodes a carboxyl-terminus-truncated Sec13 that loses its affinity to Sec31a, which leads to disintegration of the ER structure in various differentiated cells in sec13(sq198), including chondrocytes, intestinal epithelial cells and hepatocytes. Disruption of the ER structure activates an unfolded protein response that eventually causes the cells to undergo cell-cycle arrest and cell apoptosis, which arrest the growth of developing digestive organs in the mutant. Our data provide the first direct genetic evidence that COPII function is essential for the organogenesis of the digestive system.     

FgPal1 regulates morphogenesis and pathogenesis in Fusarium graminearum

Ascospores are the primary inoculum in Fusarium graminearum, a causal agent of wheat head blight. In a previous study, FgPAL1 was found to be upregulated in the Fgama1 mutant and important for ascosporogenesis. However, the biological function of this well-conserved gene in filamentous ascomycetes is not clear. In this study, we characterized its functions in growth, differentiation and pathogenesis. The Fgpal1 mutant had severe growth defects and often displayed abnormal hyphal tips. It was defective in infectious growth in rachis tissues and spreading in wheat heads. The Fgpal1 mutant produced conidia with fewer septa and more nuclei per compartment than the wild type. In actively growing hyphal tips, FgPal1-GFP mainly localized to the subapical collar and septa. The FgPal1 and LifeAct partially co-localized at the subapical region in an interdependent manner. The Fgpal1 mutant was normal in meiosis with eight nuclei in developing asci but most asci were aborted. Taken together, our results showed that FgPal1 plays a role in maintaining polarized tip growth and coordination between nuclear division and cytokinesis, and it is also important for infectious growth and developments of ascospores by the free cell formation process.     

寄主植物对桃蛀螟生长发育及产卵选择行为的影响

为明确寄主植物对桃蛀螟生长发育及产卵选择行为的影响,利用实验种群生命表和二项产卵选择试验,研究了玉米、大豆、棉花和桃等4种寄主植物对桃蛀螟种群生长发育及产卵选择性的影响。结果表明:取食棉花的桃蛀螟幼虫存活率最低、幼虫历期最长,取食玉米的幼虫存活率最高、幼虫历期最短,取食桃和大豆的幼虫存活率和历期居于棉花处理组和玉米处理组之间;玉米处理组的桃蛀螟化蛹率、蛹重和蛹历期均为最高,棉花处理组为最低,大豆和桃处理组的这些参数均显著小于玉米处理组而大于棉花处理组;发育至成虫后,取食玉米的桃蛀螟羽化率显著高于其他3个处理组;取食桃的桃蛀螟成虫寿命(雌虫和雄虫)及个体发育历期均显著高于其他3种处理组;同时取食桃的桃蛀螟单雌产卵量最高,其次是玉米处理组,两者均显著高于大豆和棉花处理组。二项产卵选择试验结果显示,桃蛀螟雌蛾在棉花和玉米处理组、玉米和大豆处理组或棉花和大豆处理组间的落卵量差异不显著;但在包含桃的处理组中,桃蛀螟在棉花、玉米或大豆处理区的落卵量均显著高于桃处理区。上述结果表明,供试4种寄主植物中,桃蛀螟偏好在棉花、玉米和大豆上产卵,其中玉米对桃蛀螟的适合度相对较高,棉花对桃蛀螟的适合度相对较低。     

酶制剂清除食源性致病菌生物被膜的研究进展

食源性致病菌对人类健康与公众安全造成了极大的危害,形成生物被膜加剧了它们的致病与耐药风险。酶具有高度专一性,可靶向作用于生物被膜中的特殊物质,从而清除食源性致病菌的生物被膜,具有重要的科研价值和广泛的应用前景。因此,文中系统地综述了相关酶制剂清除食源性致病菌生物被膜的研究进展。根据酶制剂的不同作用靶点,着重介绍了群体感应抑制酶、环二鸟苷酸代谢酶、胞外基质水解酶等酶制剂的研究现状。文中还针对抗生物被膜酶制剂的未来研究方向进行了展望,旨在为食源性致病菌生物被膜的有效控制提供新的技术与策略。     

Rumba and Haus3 are essential factors for the maintenance of hematopoietic stem/progenitor cells during zebrafish hematopoiesis

The hallmark of vertebrate definitive hematopoiesis is the establishment of the hematopoietic stem/progenitor cell (HSPC) pool during embryogenesis. This process involves a defined ontogenic switching of HSPCs in successive hematopoietic compartments and is evolutionarily conserved from teleost fish to human. In zebrafish, HSPCs originate from the ventral wall of the dorsal aorta (VDA), from which they subsequently mobilize to an intermediate hematopoietic site known as the caudal hematopoietic tissue (CHT) and finally colonize the kidney for adult hematopoiesis. Despite substantial understanding of the ontogeny of HSPCs, the molecular basis governing migration, colonization and maintenance of HSPCs remains to be explored fully. Here, we report the isolation and characterization of two zebrafish mutants, rumba(hkz1) and samba(hkz2), that are defective in generating definitive hematopoiesis. We find that HSPC initiation in the VDA and subsequent homing to the CHT are not affected in these two mutants. However, the further development of HSPCs in the CHT is compromised in both mutants. Positional cloning reveals that Rumba is a novel nuclear C2H2 zinc-finger factor with unknown function and samba encodes an evolutionarily conserved protein that is homologous to human augmin complex subunit 3 (HAUS3). Furthermore, we show that these two factors independently regulate cell cycle progression of HSPCs and are cell autonomously required for HPSC development in the CHT. Our study identifies Rumba and Haus3 as two essential regulators of HSPC maintenance during zebrafish fetal hematopoiesis.     

丁氟螨酯对二斑叶螨生长发育的影响

【目的】丁氟螨酯是一种新型酰基乙腈类非内吸性杀螨剂,对害螨的各个螨态都有很高活性,具有较高的应用价值。本文评价了丁氟螨酯对二斑叶螨生长发育的影响,以期为合理用药和二斑叶螨的综合防治提供理论依据。【方法】采用浸叶法测定丁氟螨酯对二斑叶螨成螨与卵的致死中浓度、雌成螨产卵量、各螨态存活率以及各发育历期的影响。【结果】经丁氟螨酯处理后,二斑叶螨日均产卵量和总产卵量下降,各螨态发育历期延长;LC₇₀、LC₅₀、LC₃₀剂量处理二斑叶螨雌成螨后,每雌日均产卵量为(2.09±0.17)、(3.02±0.22)、(3.39±0.13)粒,每雌总产卵量为(29.29±2.31)、(42.32±3.01)、(47.41±1.77)粒,与空白对照差异显著(P<0.05,df=3);不同剂量处理二斑叶螨卵后,各螨态发育历期的延长程度不同,但成功孵化的卵能完成发育历期,LC 70剂量延长卵历期至(4.45±0.07)d、前若螨历期至(2.75±0.04)d、后若螨历期至(2.61±0.05)d和总历期至(12.53±0.18)d,LC 50剂量延长前若螨历期至(2.52±0.08)d、后若螨历期至(2.67±0.09)d和总历期至(12.22±0.18)d,LC 30剂量延长前若螨历期至(2.45±0.06)d和总历期至(11.53±0.08)d,与空白对照差异显著(P<0.05,df=3)。【结论】丁氟螨酯能对二斑叶螨的生长发育产生明显影响,降低二斑叶螨的产卵能力,抑制卵孵化,延长发育历期,从而降低二斑叶螨种群的发育速率,对该螨的种群控制有积极意义。     

Schistosoma japonicum Soluble Egg Antigens Facilitate Hepatic Stellate Cell Apoptosis by Downregulating Akt Expression and Upregulating p53 and DR5 Expression

Background

The induction of hepatic stellate cell (HSC) apoptosis has potential as a potent strategy to diminish the progression of liver fibrosis. Previous studies have demonstrated the ability of soluble egg antigens (SEA) from schistosomes to inhibit HSC activation and to induce apoptosis in vitro. In this study, we aimed to explore the mechanism of SEA-induced apoptosis in HSCs.

Methodology/Principal Findings

In this study, we found that SEA could upregulate p53 and DR5 and downregulate the p-Akt. The apoptosis of HSCs induced by SEA could be reduced in HSCs that were treated with p53-specific siRNA and in HSCs that were treated with DR5-specific shRNA. In addition, {"type":"entrez-nucleotide","attrs":{"text":"GW501516","term_id":"289075981","term_text":"GW501516"}}GW501516, which enhances the expression of Akt, could also decrease the SEA-induced HSC apoptosis. We also found that the increased expression of p53 and DR5 induced by SEA through Mdm2 were reduced by {"type":"entrez-nucleotide","attrs":{"text":"GW501516","term_id":"289075981","term_text":"GW501516"}}GW501516.

Conclusions/Significance

Our data suggest that SEA can induce HSC apoptosis by downregulating Akt expression and upregulating p53-dependent DR5 expression.