Characterization of Aquilegia Polycomb Repressive Complex 2 homologs reveals absence of imprinting

Epigenetic regulation is important for maintaining gene expression patterns in multicellular organisms. The Polycomb Group (PcG) proteins form several complexes with important and deeply conserved epigenetic functions in both the plant and animal kingdoms. The plant Polycomb Repressive Complex 2 (PRC2) contains four core proteins, Enhancer of Zeste (E(z)), Suppressor of Zeste 12 (Su(z)12), Extra Sex Combs (ESC), and Multicopy Suppressor of IRA 1 (MSI1), and functions in many developmental transitions. In some plant species, including rice and Arabidopsis, duplications in the core PRC2 proteins allow the formation of PRC2s with distinct developmental functions. In addition, members of the plant specific VEL PHD family have been shown to associate with the PRC2 complex in Arabidopsis and may play a role in targeting the PRC2 to specific loci. Here we examine the evolution and expression of the PRC2 and VEL PHD families in Aquilegia, a member of the lower eudicot order Ranunculales and an emerging model for the investigation of plant ecology, evolution and developmental genetics. We find that Aquilegia has a relatively simple PRC2 with only one homolog of Su(z)12, ESC and MSI1 and two ancient copies of E(z), AqSWN and AqCLF. Aquilegia has four members of the VEL PHD family, three of which appear to be closely related to Arabidopsis proteins known to associate with the PRC2. The PRC2 and VEL PHD family proteins are expressed at a relatively constant level throughout Aquilegia vulgaris development, with the VEL PHD family and MSI1 expressed at higher levels during and after vernalization and in the inflorescence. Both AqSWN and AqCLF are expressed in Aquilegia endosperm but neither copy is imprinted.     

中国鳞翅目小蛾类昆虫寄主植物分析

本研究基于中国鳞翅目50科小蛾类昆虫的寄主植物数据,探索小蛾类昆虫与其寄主植物之间的关系。对昆虫种数与寄主植物种数之间进行了相关性分析,采用了z分数法对原始数据进行标准化处理以及利用箱式图对数据进行异常值检测,并对检测的结果分科进行食性分析。昆虫种数与寄主植物种数呈极显著正相关(P<0.01),相关系数为0.860;异常值检测结果显示蝙蝠蛾科、细蛾科、祝蛾科、织蛾科、斑蛾科、羽蛾科、卷蛾科和草螟科8科数据异常;这8科小蛾类昆虫除了织蛾科和祝蛾科以腐食性为主外都是植食性,其中植食性昆虫包括单食性的斑蛾科,寡食性的羽蛾科和细蛾科以及多食性的蝙蝠蛾科。而卷蛾科中黄卷蛾族和小卷蛾族的幼虫以多食性较为常见,花小卷蛾族幼虫则以单食性为主。草螟科中斑野螟亚科和禾螟亚科以单食性为主;草螟亚科和野螟亚科以寡食性为主。中国小蛾类昆虫与其寄主植物种数之间存在着正相关关系;研究结果为小蛾类分类研究以及农林害虫防治奠定了理论基础。     

链霉菌发酵麦草产木聚糖酶的试验研究

通过正交设计试验 ,找出利用链霉菌和麦草基质发酵生产木聚糖酶的试验条件。培养基 (g/L) :麦草粉 ,4 5 ;(NH4 ) 2 SO4 ,7.5 ;酵母膏 ,8;K2 HPO4 ·3H2 O ,1;MgSO4 ·7H2 O ,0 .5 ;NaCl,0 .3。接种量为 5 .0× 10 8个孢子 / 5 0mL培养基 ,振荡培养 (12 0r/min) 5d     

A PHYLOGENETIC ANALYSIS OF BODY SIZE EVOLUTION AND BIOGEOGRAPHY IN CHUCKWALLAS (SAUROMALUS) AND OTHER IGUANINES

The evolution of body size was reconstructed in chuckwallas (genus Sauromalus), large herbivorous lizards of southwest North America, using a phylogeny derived from sequence variation in the mitochondrial cytochrome b gene. The body mass of two endemic island species (S. hispidus and S. varius) is typically fivefold larger than mainland species. We tested the hypothesis that large body size has evolved on these islands in response to local ecological conditions against the alternative hypothesis that large size is simply retained from large iguanine ancestors. The most parsimonious tree topology depicts the insular gigantic Sauromalus as monophyletic, having diverged from a common ancestor on the Baja California peninsula after the radiation of smaller bodied clades. In a robustness analysis of this topology, we found general support for this tree over alternative topologies representing minimum evolution hypotheses that imply large body size is retained from large iguanine ancestors. The most parsimonious reconstruction of body size evolution implies a change from large to small size after the Sauromalus ancestor diverged from Iguana, and one reversal back to large size within Sauromalus. The large size increase in the gigantic clade contrasts with evolutionary stasis of small body size (for an iguanine) in mainland populations. The gigantic species show 3–4% total sequence divergence from S. obesus populations on the nearby Baja California peninsula, and mainland populations of S. obesus obesus show similar levels of divergence from each other. An analysis of character transitions and comparative behavior implicates predation, and its relaxation on isolated islands, as a strong selective force in Sauromalus. Patterns of genetic differentiation in Sauromalus and biogeographic implications are discussed.     

Reaction of aspirin with cysteinyl residues of lens γ-crystallins: a mechanism for the proposed anti-cataract effect of aspirin

Incubation of lens crystallins with aspirin inhibits the development of opacities caused by cyanate. Cyanate-induced opacities are thought to be due to carbamylation of the lysyl residues which causes a decrease in the protein charge and subsequent conformational changes that permit disulfide bonding. Because aspirin can also react with lysyl residues, it has been proposed that the aspiring inhibition of cataractogonesis is due to acetylation of the lysyl which would block their reaction with cyanata. However, acetylation oflysyl residues also lowers the protein charge and would be expected to effect changes in protein conformation similar to those caused by carbamylation. Therefore, acetylation of the lysyl residues is not a satisfactory explanation for the inhibitory effect of aspirin on lens opacification. Our investigations of the reactions of cyanate and aspirin with bovine γ_II-crystallins show that the cysteinyl residues are also carbamylated and acetylated at pH 7.4. At this pH, the carbamylation at the cysteinyl residues is reversible, leading to regeneration of the thiol group and disulfide bonding. In contrast, the acetylation at cysteinyl residues is stable at pH 7.4 and can prevent disulfide bonding. This difference in stability explains how cyanate promotes, and aspirin inhibits, cataractogenesis.     

Lycopene prevention of oxysterol-induced proinflammatory cytokine cascade in human macrophages: inhibition of NF-κB nuclear binding and increase in PPARγ expression

It is now well accepted that oxysterols play important roles in the formation of atherosclerotic plaque, involving cytotoxic, pro-oxidant and proinflammatory processes. It has been recently suggested that tomato lycopene may act as a preventive agent in atherosclerosis, although the exact mechanism of such a protection is not clarified. The main aim of this study was to investigate whether lycopene is able to counteract oxysterol-induced proinflammatory cytokines cascade in human macrophages, limiting the formation of atherosclerotic plaque. Therefore, THP-1 macrophages were exposed to two different oxysterols, such as 7-keto-cholesterol (4-16 μM) and 25-hydroxycholesterol (2-4 μM), alone and in combination with lycopene (0.5-2 μM). Both oxysterols enhanced pro-inflammatory cytokine [interleukin (IL)-1β, IL-6, IL-8, tumor necrosis factor α) secretion and mRNA levels in a dose-dependent manner, although at different extent. These effects were associated with an increased reactive oxygen species (ROS) production through an enhanced expression of NAD(P)H oxidase. Moreover, a net increment of phosphorylation of extracellular regulated kinase 1/2, p-38 and Jun N-terminal kinase and of nuclear factor kB (NF-κB) nuclear binding was observed. Lycopene prevented oxysterol-induced increase in pro-inflammatory cytokine secretion and expression. Such an effect was accompanied by an inhibition of oxysterol-induced ROS production, mitogen-activated protein kinase phosphorylation and NF-κB activation. The inhibition of oxysterol-induced cytokine stimulation was also mimicked by the specific NF-κB inhibitor pyrrolidine dithiocarbamate. Moreover, the carotenoid increased peroxisome proliferator-activated receptor γ levels in THP-1 macrophages. Taken all together, these data bring new information on the anti-atherogenic properties of lycopene, and on its mechanisms of action in atherosclerosis prevention.     

Identification of a novel type of polyunsaturated fatty acid synthase involved in arachidonic acid biosynthesis

Arachidonic acid (ARA) is a polyunsaturated fatty acid (PUFA) and an essential component of membrane lipids. However, the PUFA synthase required for ARA biosynthesis has not been identified in any organism. To identify the PUFA synthase producing ARA, we determined the draft genome sequence of the marine bacterium Aureispira marina, which produces a high level of ARA, and found a gene cluster encoding a putative PUFA synthase for ARA production. Expression of the gene cluster in Escherichia coli induced production of ARA, demonstrating that the gene cluster encodes a PUFA synthase required for ARA biosynthesis.