Doubling genome size without polyploidization: dynamics of retrotransposition-driven genomic expansions in Oryza australiensis, a wild relative of rice

Retrotransposons are the main components of eukaryotic genomes, representing up to 80% of some large plant genomes. These mobile elements transpose via a "copy and paste" mechanism, thus increasing their copy number while active. Their accumulation is now accepted as the main factor of genome size increase in higher eukaryotes, besides polyploidy. However, the dynamics of this process are poorly understood. In this study, we show that Oryza australiensis, a wild relative of the Asian cultivated rice O. sativa, has undergone recent bursts of three LTR-retrotransposon families. This genome has accumulated more than 90,000 retrotransposon copies during the last three million years, leading to a rapid twofold increase of its size. In addition, phenetic analyses of these retrotransposons clearly confirm that the genomic bursts occurred posterior to the radiation of the species. This provides direct evidence of retrotransposon-mediated variation of genome size within a plant genus.     

Cloning and characterization of CYP51 from Mycobacterium avium

Mycobacterium avium complex (MAC) causes chronic lung disease in immunocompetent people and disseminated infection in patients with AIDS. MAC is intrinsically resistant to many conventional antimycobacterial agents, it develops drug resistance rapidly to macrolide antibiotics, and patients with MAC infection experience frequent relapses or the inability to completely eradicate the infection with current treatment. Treatment regimens are prolonged and complicated by drug toxicity or intolerances. We sought to identify biochemical pathways in MAC that can serve as targets for novel antimycobacterial treatment. The cytochrome P450 enzyme, CYP51, catalyzes an essential early step in sterol metabolism, removing a methyl group from lanosterol in animals and fungi, or from obtusifoliol in plants. Azoles inhibit CYP51 function, leading to an accumulation of methylated sterol precursors. This perturbation of normal sterol metabolism compromises cell membrane integrity, resulting in growth inhibition or cell death. We have cloned and characterized a CYP51 from MAC that functions as a lanosterol 14alpha-demethylase. We show the direct interactions of azoles with purified MAC-CYP51 by absorbance and electron paramagnetic resonance spectroscopy, and determine the minimum inhibitory concentrations (MICs) of econazole, ketoconazole, itraconazole, fluconazole, and voriconazole against MAC. Furthermore, we demonstrate that econazole has a MIC of 4 mug/ml and a minimum bacteriocidal concentration of 4 mug/ml, whereas ketoconazole has a MIC of 8 mug/ml and a minimum bacteriocidal concentration of 16 mug/ml. Itraconazole, voriconazole, and fluconazole did not inhibit MAC growth to any significant extent.     

肝硬化胃食管静脉曲张与曲张破裂出血的治疗和预防

<正>这份指南已经被美国肝病学会和美国胃食管医师协会所认可,体现了两个协会对胃底食管静脉曲张与曲张破裂出血的治疗和预防的观点。前言本指南采用数据支持的方法建立,建立依据如下:(1)正式回顾和分析近期发表的关于该主题的研究文献(Medline搜索);(2)领域专家们的某些会议意见;(3)美国医师协会使用的健康行为评估及预实践指导手册;(4)某些政策方针,包括美国肝病研究协会关于发展使用实践指南的政策声明     

Chloramphenicol resistant Salmonella typhi: the cause of recent out-break of enteric fever in Calcutta.

Fifty one strains of Salmonella typhi were isolated during the recent outbreak of enteric fever in and around Calcutta. Forty strains were multidrug resistant including Chloramphenicol. Minimum inhibitory concentrations (MIC) of Chloramphenicol was between 200 mcg per ml and 500 mcg per ml. All these strains were sensitive to Cephalexine, Gentamicin, Furazolidine and Ciproflexacin. Widal test was done in all the cases but the result was inconclusive.     

Alterations and reversibility of the effects of gossypol acetic acid on the intestinal uptake of end product nutrients in normal and protein calorie-malnourished male rats

The effects of gossypol acetic acid, an experimental male antifertility agent, 20 mg/kg body weight daily for 15 days and its subsequent withdrawal have been investigated on the intestinal uptake of certain end product nutrients, namely glucose, leucine, alanine and calcium, in normal and protein-calorie-malnourished (PCM) male albino rats. Gossypol feeding caused a reduction in body weight, intestinal weight and length, protein and nucleic acid contents in both normal and PCM animals. Serum parameters, e.g. total protein, albumin and globulin, also showed a decrease in PCM rats. PCM per se considerably elevated the uptake of nutrients but gossypol feeding inhibited the uptake of nutrients both in normal-fed and malnourished animals. Gossypol caused a decrease in the Na(+)-dependent (active) glucose uptake while the Na(+)-independent (passive) process was not altered. The kinetic parameters of glucose uptake indicate that gossypol might be interfering with the transport/carrier protein of these nutrients as reduction in maximum uptake velocity (Jmax) of these systems was observed without, however, any change in the affinity constant (Kt).