膜翅目精子结构研究新进展

根据观察,膜翅目昆虫精子由顶体,精核,中部,尾部四个主要部分构成。顶体具顶体丝,中部具轴丝,中部与精核间具线粒体衍生物。本文同时对膜翅目,分别隶属12个科,10个总科中的2个亚目昆虫精子的顶体、精核、线粒体衍生物、轴丝等结构的研究状况进行概括,并应用精子结构特征对上述类群的系统发育状况进行讨论。     

PI3K/Akt Signal Pathway Involved in the Cognitive Impairment Caused by Chronic Cerebral Hypoperfusion in Rats

Chronic cerebral hypoperfusion (CCH) is a common pathophysiological state that usually occurs in conditions such as vascular dementia and Alzheimer''s disease, both of which are characterized by cognitive impairment. In previous studies we found that learning capacity and memory were gradually impaired with CCH, which altered the expression of synaptophysin, microtubule associated protein-2, growth associated protein-43, brain-derived neurotrophic factor, nerve growth factor, N-methyl-D-aspartate receptor subunit 1, cAMP response element-binding protein and tau hyperphosphorylation in the hippocampus. However, the molecular basis of cognitive impairment in CCH remains obscure. Here we explore the hypothesis that the phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) signal pathway is involved in this type of cognitive impairment. In order to determine if the expression of PI3K, Akt and phosphorylated Akt (p-Akt) proteins are altered at different stages of CCH with differing levels of cognitive impairment. we performed permanent, bilateral occlusion of the common carotid arteries (2-VO) to induce CCH. Adult male SD rats were randomly divided into sham-operated group, 2-VO 1 week group, 2-VO 4 weeks group and 2-VO 8 weeks group. Behavior tests were utilized to assess cognitive abilities, while western blots were utilized to evaluate protein expression. Rats in the 2-VO groups spent less time exploring novel objects than those in the sham-operated group, and the discrimination ratio of the 2-VO 8 weeks group and the sham-operated group were higher than chance (0.50). Escape latencies in the Morris water maze task in the 2-VO 1 week group were longer than those in the sham-operated group on day 4 and day 5, while escape latencies in the 2-VO 4 weeks group were longer than those in the sham-operated group from day 3 to day 5. Escape latencies in 2-VO 8 weeks group were longer than those in the sham-operated group from day 2 to day 5. NE (northeast) square swimming times in the 2-VO 1 week group, 2-VO 4 weeks group and 2-VO 8 weeks group were shorter than that in the sham-operated group. Western blotting showed that the PI3K expression in the 2-VO 1 week group was lower than that in sham-operated group, while p-Akt expression in the 2-VO 8 weeks group was higher than that in the sham-operated group. There was a linear relationship between the PI3K expression and the discrimination ratio, as well as a linear relationship between the PI3K and NE square swimming time. Thus, we propose that the PI3K/Akt signal pathway is an important cell pathway that is associated with the cognitive impairment following CCH.     

Asymmetric biocatalysis of S-3-amino-3-phenylpropionic acid with new isolated Methylobacterium Y1-6

β-amino acids are widely used in drug research, and S-3-amino-3-phenylpropionic acid (S-APA) is an important pharmaceutical intermediate of S-dapoxetine, which has been approved for the treatment of premature ejaculation. Chiral catalysis is an excellent method for the preparation of enantiopure compounds. In this study, we used (±)-ethyl-3-amino-3-phenylpropanoate (EAP) as the sole carbon source. Three hundred thirty one microorganisms were isolated from 30 soil samples, and 17 strains could produce S-APA. After three rounds of cultivation and identification, the strain Y1-6 exhibiting the highest enantioselective activity of S-APA was identified as Methylobacterium oryzae. The optimal medium composition contained methanol (2.5 g/L), 1,2-propanediol (7.5 g/L), soluble starch (2.5 g/L), and peptone (10 g/L); it was shaken at 220 rpm for 4–5 days at 30 °C. The optimum condition for biotransformation of EAP involved cultivation at 37 °C for 48 h with 120 mg of wet cells and 0.64 mg of EAP in 1 ml of transfer solution. Under this condition, substrate ee was 92.1% and yield was 48.6%. We then attempted to use Methylobacterium Y1-6 to catalyze the hydrolytic reaction with substrates containing 3-amino-3-phenyl-propanoate ester, N-substituted-β-ethyl-3-amino-3-phenyl-propanoate, and γ-lactam. It was found that 5 compounds with ester bonds could be stereoselectively hydrolyzed to S-acid, and 2 compounds with γ-lactam bonds could be stereoselectively hydrolyzed to (-)-γ-lactam.     

伊洛河流域外来草本植物分布格局

外来生物入侵及其防治已经成为生态学关注的重点和热点问题.目前的研究主要集中在外来入侵种上,然而入侵种仅占外来种中很少一部分,因此,研究外来种现有分布格局对研究生物入侵及其防治有重要意义.以伊洛河流域草本植物群落中的外来种为对象,沿河从河源地到入黄河口选取典型样地,在调查流域内草本植物群落中物种组成的基础上选取外来种,并对外来种种类组成及其分布格局进行研究.结果表明:流域内有外来草本植物27种,分属于15科,种类较多的科为菊科、苋科和豆科;引入方式以有意引种为主.流域横向不同生境间,河滩地在水流的养分富集、季节性洪水物理干扰及人为活动扰动作用下,呈现出受外来种分布较多,而受人类活动扰动最强且营养丰富的农田分布较小的分布格局;纵向环境梯度下,上游河源山地属于自然植被区,人为干扰较轻,且受外来种影响较小;中游丘陵区从自然生态系统向农业生态系统的过渡区域,人类活动的扰动有所加强;下游平原农业区,人类活动强烈,区域内以人工生态系统为主,群落物种组成简单但受外来种影响最大,受自然环境和人类活动的双重影响.不同物种在不同生境间差异明显,其中,小蓬草、钻叶紫菀和反枝苋广泛分布于3种生境中.总体上,伊洛河外来草本植物分布格局在自然因素的基础上强烈受人为因素的影响,呈现出从上游到下游逐渐增多的趋势.     

人工引入传粉者对油茶丰产的意义及潜在的生物安全

动物传粉在全球生态系统中提供重要服务,全球农业生产对动物传粉服务的需求稳定增长。油茶是我国特有的重要木本油料植物,栽培历史悠久,由于严格自交不亲和而高度依赖动物传粉。基于我国油茶产业发展的新形势,从资源分配和花粉限制等生态因素系统分析了油茶产量受限制的原因,提出油茶的传粉者限制效果等同于花粉限制效果,人工引入潜在的高效传粉者是解除油茶资源限制措施和传粉生态限制措施之间冲突、提高油茶产量的有效途径。论述了人工引入传粉者传粉服务的优势和挑战。对人工引入传粉者,特别是外来传粉者所面临的潜在风险和控制途径进行了梳理,提出从传粉生态服务解决油茶产量和质量问题的新思路。全文旨在为人工引入传粉者在油茶丰产中的作用提供理论与科学依据,以期促进油茶产业健康有序发展。     

Chromosome banding and FISH with rDNA probe in the diploid and tetraploid loach Misgurnus anguillicaudatus

The chromosomes of the diploid and tetraploid loach Misgurnus anguillicaudatus were analyzed by staining with Ag, chromomycin A₃ (CMA₃)/distamycin A (DA), and DA/4′,6-diamidino-2-phenylindole (DAPI), and using fluorescence in situ hybridization (FISH) with 5.8S + 28S rDNA as a probe. Nucleolus organizer regions (NORs) were mapped to the telomeric region of the short arms of the largest (first) metacentric chromosome pair in the diploid loach with 2n = 50 and the homologous quartet in the tetraploid loach with 4n = 100. The NORs were positive at the same region of the first metacentric chromosome for Ag and CMA₃/DA stainings, but negative for DA/DAPI staining. Four signals at the homologs within the same quartet suggest the duplication of the entire genome from diploid to tetraploid status. However, a size difference was detected between the rDNA signals by FISH and CMA₃ banding.     

Differences in Variation of Human Immunodeficiency Virus Type 1 Sequences from Henan and Shanghai Regions of China

Illegally paid blood donation was a risk factor for HIV acquisition exclusively in Henan and Hubei Provinces of China,and not in Shanghai.Nucleotide sequences in the gag and env genes of HIV-1 were compared between isolates from Henan and Shanghai regions of China to test whether an expected higher degree of a common source of infections from this unique blood donation transmission risk would be evident as decreased variation among Henan isolates in an exploratory cross-sectional analysis.Among 38 isolates studied,23 of 23(100%)from Henan and 8 of 15(54%)from Shanghai were subtype B.In addition,fewer sequence differences were found in gp41 of subtype B isolates from Henan than from Shanghai isolates.Further studies with additional controls are therefore warranted to confirm the role of the degree of a common source of infections in differences in HIV variation across populations.     

Improving simvastatin bioconversion in Escherichia coli by deletion of bioH

Simvastatin is an important cholesterol lowering compound and is currently synthesized from the natural product lovastatin via multistep chemical synthesis. We have previously reported the use of an Escherichia coli strain BL21(DE3)/pAW31 as the host for whole-cell biocatalytic conversion of monacolin J acid to simvastatin acid. During fermentation and bioconversion, unknown E. coli enzyme(s) hydrolyzed the membrane permeable thioester substrate dimethylbutyryl-S-methyl mercaptopropionate (DMB-S-MMP) to the free acid, significantly decreased the efficiencies of the whole-cell bioconversion and the downstream purification steps. Using the Keio K-12 Singe-Gene Knockout collection, we identified BioH as the sole enzyme responsible for the observed substrate hydrolysis. Purification and reconstitution of E. coli BioH activity in vitro confirmed its function. BioH catalyzed the rapid hydrolysis of DMB-S-MMP with kcat and Km values of 260+/-45 s(-1) and 229+/-26 microM, respectively. This is in agreement with previous reports that BioH can function as a carboxylesterase towards fatty acid esters. YT2, which is a delta bioH mutant of BL21(DE3), did not hydrolyze DMB-S-MMP during prolonged fermentation and was used as an alternative host for whole-cell biocatalysis. The rate of simvastatin acid synthesis in YT2 was significantly faster than in BL21(DE3) and 99% conversion of 15 mM simvastatin acid in less than 12 h was achieved. Furthermore, the engineered host required significantly less DMB-S-MMP to be added to accomplish complete conversion. Finally, simvastatin acid synthesized using YT2 can be readily purified from fermentation broth and no additional steps to remove the hydrolyzed dimethylbutyryl-S-mercaptopropionic acid is required. Together, the proteomic and metabolic engineering approaches render the whole-cell biocatalytic process more robust and economically attractive.