Molecules and mechanisms controlling the active DNA demethylation of the mammalian zygotic genome

The active DNA demethylation in early embryos is essential for subsequent development. Although the zygotic genome is globally demethylated, the DNA methylation of imprinted regions, part of repeat sequences and some gamete-specific regions are maintained. Recent evidence has shown that multiple proteins and biological pathways participate in the regulation of active DNA demethylation, such as TET proteins, DNA repair pathways and DNA methyltransferases. Here we review the recent understanding regarding proteins associated with active DNA demethylation and the regulatory networks controlling the active DNA demethylation in early embryos.     

Application of RAPD Analysis in the Study on the Origin of Chinese Cultivated Chrysanthemum

The RAPD ( random amplified polymorphic DNA) markers generated by 22 20-ruer primers, discriminated 7 wild Dendraathema species, 14 cultivars and 5 interspecific hybrids by banding profiles. Of 224 bands observed, 34 bands (15%) were polymorphic. Cluster analysis based on UPGMA method indicated that: of 7 wild species, D. indicum, D. vestitum and D. nankingense were closest to the cultivated groups while D. zawadskii was most distinct. Genetic distances between the former three species and cuhivars were less than 0.40 but those between D. zawadskii and cuhivars were more than 0.50. According to the RAPD analysis and previous research, the authors discussed the origin of Chinese cultivated chrysanthemum and proposed that the cuhivars of this genus may derive from D. indicum, D. vestitum and D. nankingense. The results have provided basic research data for study on the origin of Chinese cultivated chrysanthemum.     

Cumulus Cells Block Oocyte Meiotic Resumption via Gap Junctions in Cumulus Oocyte Complexes Subjected to DNA Double-Strand Breaks

During mammalian oocyte growth, genomic DNA may accumulate DNA double-strand breaks (DSBs) induced by factors such as reactive oxygen species. Recent evidence demonstrated that slight DSBs do not activate DNA damage checkpoint proteins in denuded oocytes. These oocytes, even with DNA DSBs, can resume meiosis and progress to metaphase of meiosis II. Meiotic resumption in oocytes is also controlled by the surrounding cumulus cells; accordingly, we analyzed whether cumulus-cell enclosed oocytes (CEOs) with DNA damage are able to resume meiosis. Compared with DNA-damaged denuded oocytes, we found that meiotic resumption rates of CEOs significantly decreased. To assess the mechanism by which cumulus cells block meiotic resumption in CEOs with DNA DSBs, we treated the cumulus oocyte complex with the gap junction inhibitor carbenoxolone and found that carbenoxolone can rescue the block in CEO meiosis induced by DNA DSBs. Since cumulus cell-synthesized cAMPs can pass through the gap junctions between oocyte and cumulus cell to block oocyte meiosis, we measured the expression levels of adenylate cyclase 1 (Adcy1) in cumulus cells, and G-protein coupled receptor 3 (Gpr3) and phosphodiesterase 3A (Pde3a) in oocytes, and found that the mRNA expression level of Adcy1 increased significantly in DNA-damaged cumulus cells. In conclusion, our results indicate that DNA DSBs promote cAMP synthesis in cumulus cells, and cumulus cAMPs can inhibit meiotic resumption of CEOs through gap junctions.     

Allosteric Regulation of a Protein Acetyltransferase in Micromonospora aurantiaca by the Amino Acids Cysteine and Arginine

ACT domains (amino acid-binding domains) are linked to a wide range of metabolic enzymes that are regulated by amino acid concentration. Seventy proteins with ACT-GCN5-related N-acetyltransferase (GNAT) domain organization were found in actinomycetales. In this study, we investigate the ACT-containing GNAT acetyltransferase, Micau_1670 (MaKat), from Micromonospora aurantiaca ATCC 27029. Arginine and cysteine were identified as ligands by monitoring the conformational changes that occur upon amino acids binding to the ACT domain in the MaKat protein using FRET assay. It was found that MaKat is an amino acid-regulated protein acetyltransferase, whereas arginine and cysteine stimulated the activity of MaKat with regard to acetylation of acetyl-CoA synthetase (Micau_0428). Our research reveals the biochemical characterization of a protein acetyltransferase that contains a fusion of a GNAT domain with an ACT domain and provides a novel signaling pathway for regulating cellular protein acetylation. These findings indicate that acetylation of proteins and acetyltransferase activity may be tightly linked to cellular concentrations of some amino acids in actinomycetales.     

温度对拟小食螨瓢虫发育和繁殖的影响

拟小食螨瓢虫是热带地区香蕉、番木瓜、橡胶和木薯等作物上有害叶螨的重要天敌。在室内条件下,以皮氏叶螨Tetranychus piercei为食物,观察了不同温度(16℃,20℃,24℃,28℃,32℃)对拟小食螨瓢虫生长发育及繁殖的影响。结果表明:拟小食螨瓢虫卵、幼虫和蛹的历期在32℃下最短,分别为2.38,4.26和3.04 d;16℃时最长,分别为12.48,25.10和16.12 d,雌成虫寿命在16℃时长达142.53 d,而在32℃时为95.46 d。世代发育起点温度和有效积温分别为13.29℃和227.63日度。成虫产卵量在28℃最高,达595.49粒/雌,在16℃最低,为125.05粒/雌。内禀增长率(rm)在32℃达到最大(0.2063),而在16℃时最小(0.0342)。结果表明拟小食螨瓢虫有较好的高温耐受性,研究结果可为该瓢虫人工繁育的温度条件提供依据。     

Comorbidities among the HIV-Infected Patients Aged 40 Years or Older in Taiwan

Background

With the widespread use of combination antiretroviral therapy (cART), life expectancy of HIV-infected patients has significantly prolonged. An increasing number of HIV-infected patients are aging and concurrent use of medications are not uncommon for management of metabolic complications and cardiovascular diseases related to aging and prolonged exposure to cART.

Methods

We reviewed medical records of all HIV-infected patients aged 40 years or older who had been followed at a university hospital for HIV care in Taiwan between January and December 2013. A standardized case record form was used to collect information on demographics and clinical characteristics, comorbidity, cART, and concurrent medications.

Results

During the study period, 610 patients aged 40 to 49 years (mean, 44.1) and 310 aged 50 years or older (mean, 58.8) sought HIV care at this hospital. Compared with patients aged 40 to 49 years, those aged 50 years or older were significantly more likely to be female (15.9% vs 3.8%); to have received cART (97.7% vs 94.8%) and a lower plasma HIV RNA load (1.6 vs 1.7 log₁₀ copies/ml); and to have diabetes mellitus (18.4% vs 4.6%), hypertension (31.0% vs 10.8%), hyperlipidemia (29.4% vs 11.6%), coronary artery disease (6.8% vs 0.5%), and an estimated glomerular filtration rate <60 ml/min/1.73 m² (11.5% vs 2.7%); and were significantly less likely to have syphilis. Other than HIV infection, patients aged 50 years or older were more likely to have been receiving two or more concurrent medications than those aged 40 to 49 years (22.9% vs 6.4%).

Conclusions

Our findings show a significant proportion of the HIV-infected patients aged 50 years or older have multiple comorbidities that may increase the risk for cardiovascular and renal complications. Issues of poly-pharmacy among the HIV-infected patients who are aging should be addressed to ensure adherence and minimize drug-drug interactions.     

植物花色形成及其调控机理

综述了植物花色的表现、起源与进化、功能及其调控机制.植物花色主要表现为单色、变色和杂色,是长期进化的结果,主要功能是指示传粉者和保护花器官.花色素主要包括类黄酮、类胡萝卜素和生物碱.花色素的存在及其变化是植物花色表现的化学机制,色素在花瓣中的空间分布及其对光的作用是花色表现的解剖学和光学机制,细胞液pH值、花发育阶段和植物激素是花色表现的植物生理学机制.传粉者、真菌侵染、机械损伤、园艺措施、光、温度、水分、矿质营养和糖等是影响花色的外部因蝌素.花瓣彩斑主要由基因突变或病毒入侵而形成.     

棉铃虫幼虫唾液腺cDNA文库的构建及EST分析

棉铃虫Helicoverpa armigera (Hübner)幼虫唾液中的各种酶类及各种生化组分在棉铃虫与植物相互作用及协同进化中起到重要作用; 唾液腺是棉铃虫唾液成分的合成器官。本研究通过构建棉铃虫幼虫唾液腺全长cDNA文库, 测序得到1 502条EST序列, 聚类分析后获得821个unigenes, 为筛选棉铃虫与寄主互作信号因子提供基因信息资源。使用Blast2 GO软件对821个unigenes进行了比对和功能注释, 初步获得棉铃虫幼虫唾液腺中mRNA的构成特征。结果显示, 在棉铃虫唾液腺ESTs文库中, 鉴定得到脂类相关消化酶基因17个, 糖类相关消化酶基因5个, 半胱氨酸蛋白酶基因1个, 丝氨酸蛋白酶基因20个（其中16个为新发现）, 提示唾液腺的主要功能是分泌消化酶进行预消化; 还发现在棉铃虫幼虫唾液腺中存在表皮蛋白、 气味结合蛋白和化学感受蛋白基因。结果为研究棉铃虫预消化系统打下基础。