动物生态学在大兴安岭流行性出血热宿主动物研究中的重要作用

在流行病的三大流行环节中,病原的宿主与疾病的传播媒介常是动物。动物学研究,尤其是动物生态学研究,常能在病原体尚未分离出来的情况下,判别出自然疫源性疾病的宿主动物,找出最主要的传播途径,从而有效地防治     

DHA和EPA的研究现状与趋势

本文综述了DHA和EPA的研究背景、生物体内的代谢、生理作用及开发应用,并据此提出今后进一步开展该方面研究的方向。     

大兴安岭及三江平原黑线姬鼠的种群年龄组成

1.1957年5—10月,作者曾对大兴安岭及东北三江平原夏、秋季黑线姬鼠的种群年龄进行了研究。所用标本包括大兴安岭伊图里河与呼玛及三江平原抚远与富锦等地,共795只。 依臼齿咀嚼面釉质磨损程度,将标本划分为幼体、亚成体、成体Ⅰ、成体Ⅱ及老体等5个年龄组,划分标准如下: (1)幼体:M~3还没有长成,咀嚼面与M~1及M~2尚未达到同一平面。 (2)亚成体:M~3长成,与M~1及M~2咀嚼面达一平面。M~1及M~2齿突虽已磨损,联成横嵴,且有纵的联接出现,但第2与第3横嵴的两端尚未联接成为一个封闭的环。雄体有2/3个体的睾丸降落,副睾有精子出现;雌体有1/3的个体怀孕。 (3)成体Ⅰ(年轻的成体):M~1的第2及第3横嵴的两端,已由纵的联接相接联成一个封闭的环。雄体4/5个体睾丸降落,副睾有精子;雌体1/2的个体有孕。 (4)成体Ⅱ(年老的成体):M~2的第2及第3横嵴的两端由纵的联接联成一个封闭的环。雄体100%睾丸降落,副睾有精子;雌体60%有孕。繁殖力已达到最旺盛的阶段。 (5)老体:咀嚼面已大部分磨平。 2.黑线姬鼠年龄组成具有明显地性别及地区差异。通过卡方试验,虽然在夏秋季黑线姬鼠逐月年龄组成的差异不显著,且皆以亚成体组占优势,但是若结合繁殖情况加以分析,9月下旬黑线姬鼠即停止繁殖,估计冬末春初由于没有幼体继续补充入种群,而     

大兴安岭森林采伐地区人房内鼠类区系的演替现象

在人类活动影响下,动物区系常有阴显的演替现象。作者在内蒙古大兴安岭牙林铁路沿线工作期间,曾进行了人房内小形啮齿类区系演替现象的观察。分别选择了新开发的、采伐后1—5年和15—30年的林区,对人房内小形啮齿类的组成及     

莫氏田鼠( Microtus maximowiczii Schrenck，1858)生态的初步观察

莫氏田鼠在外形上,与东方田鼠(Microtus forti Buc-hner,1889)十分相似。但其腹部与足部的颜色较黑,踱部有6个肉垫,眶间嵴在年老的标本,比东方田鼠明显。它的脑颅较短,颧骨较高,头骨前部略低,都足以与东方田鼠区别。     

黄土高原地区春小麦对有限灌溉的反应及其生理生态基础

从对黄土高原地区有限灌溉条件下作物生理生态反应的众多研究中得出：（1）水分轻度亏缺时,作物可通过根信号物质ABA调节叶片的气孔导度。非水力根信号作用太强,可因降低光合作用而减少干物质生产和影响干物质分配模式而影响产量和水分利用效率,故削弱非水力根信号的作用将有利于提高产量。（2）浅层根系占根系总量比值越高,对干旱越敏感,表现为根信号能力增强;深层根系所占比例越高,越有利于土壤深层水分利用,并可削弱根信号,同理,给土壤中下层补水或采用播种前灌溉,可因为减少了无效蒸发,且削弱根信号而提高水分利用率。（3）本地区有限灌溉的最佳时期由于降水变率较高而变得较为复杂,不同降水年型,最佳灌溉时期差异很大,对有限灌溉进行科学管理还需要做更多的研究工作。     

Proteome response to the panneural expression of human wild-type alpha-synuclein: a Drosophila model of Parkinson's disease

The alpha-synuclein protein is associated with several neurodegenarative diseases, including Parkinson's disease (PD). In humans, only mutated forms of alpha-synuclein are linked to PD; however, panneural expression of human wild-type (WT) alpha-synuclein induces Parkinson's like-symptoms in Drosophila. Here, we report a quantitative proteomic analysis of WT alpha-synuclein transgenic flies with age-matched controls at the presymptomatic stage utilizing a global isotopic labeling strategy combined with multidimensional liquid chromatographies and tandem mass spectrometry. The analysis includes two biological replicates, in which samples are isotopically labeled in forward and reverse directions. In total, 229 proteins were quantified from assignments of at least two peptide sequences. Of these, 188 (82%) proteins were detected in both forward and reverse labeling measurements. Twelve proteins were found to be differentially expressed in response to the expression of human WT alpha-synuclein; down-regulations of larval serum protein 2 and fat body protein 1 levels were confirmed by Western blot analysis. Gene Ontology analysis indicates that the dysregulated proteins are primarily associated with cellular metabolism and signaling, suggesting potential contributions of perturbed metabolic and signaling pathways to PD. An increased level of the iron (III)-binding protein, ferritin, typically found in the brains of PD patients, is also observed in presymptomatic WT alpha-synuclein expressing animals. The observed alterations in both pathology-associated and novel proteins may shed light on the pathological roles of alpha-synuclein that may lead to the development of diagnostic strategies at the presymptomatic stage.     

Fast and accurate identification of semi-tryptic peptides in shotgun proteomics

MOTIVATION: One of the major problems in shotgun proteomics is the low peptide coverage when analyzing complex protein samples. Identifying more peptides, e.g. non-tryptic peptides, may increase the peptide coverage and improve protein identification and/or quantification that are based on the peptide identification results. Searching for all potential non-tryptic peptides is, however, time consuming for shotgun proteomics data from complex samples, and poses a challenge for a routine data analysis. RESULTS: We hypothesize that non-tryptic peptides are mainly created from the truncation of regular tryptic peptides before separation. We introduce the notion of truncatability of a tryptic peptide, i.e. the probability of the peptide to be identified in its truncated form, and build a predictor to estimate a peptide's truncatability from its sequence. We show that our predictions achieve useful accuracy, with the area under the ROC curve from 76% to 87%, and can be used to filter the sequence database for identifying truncated peptides. After filtering, only a limited number of tryptic peptides with the highest truncatability are retained for non-tryptic peptide searching. By applying this method to identification of semi-tryptic peptides, we show that a significant number of such peptides can be identified within a searching time comparable to that of tryptic peptide identification.     

The importance of the amide bond nearest the thiol group in enzymatic reactions of coenzyme A

Analogues of coenzyme A (CoA) and of CoA thioesters have been prepared in which the amide bond nearest the thiol group has been modified. An analogue of acetyl-CoA in which this amide bond is replaced with an ester linkage was a good substrate for the enzymes carnitine acetyltransferase, chloramphenicol acetyltransferase, and citrate synthase, with K(m) values 2- to 8-fold higher than those of acetyl-CoA and V(max) values from 14 to >80% those of the natural substrate. An analogue in which an extra methylene group was inserted between the amide bond and the thiol group showed less than 4-fold diminished binding to the three enzymes but exhibited less than 1% activity relative to acetyl-CoA with carnitine acetyltransferase and no measurable activity with the other two enzymes. Analogues of several CoA thioesters in which the amide bond was replaced with a hemithioacetal linkage exhibited no measurable activity with the appropriate enzymes. The results indicate that some aspects of the amide bond and proper distance between this amide and the thiol/thioester moiety are critical for activity of CoA ester-utilizing enzymes.     

Characterization of chlorophenol 4-monooxygenase (TftD) and NADH:flavin adenine dinucleotide oxidoreductase (TftC) of Burkholderia cepacia AC1100

Burkholderia cepacia AC1100 uses 2,4,5-trichlorophenoxyacetic acid, an environmental pollutant, as a sole carbon and energy source. Chlorophenol 4-monooxygenase is a key enzyme in the degradation of 2,4,5-trichlorophenoxyacetic acid, and it was originally characterized as a two-component enzyme (TftC and TftD). Sequence analysis suggests that they are separate enzymes. The two proteins were separately produced in Escherichia coli, purified, and characterized. TftC was an NADH:flavin adenine dinucleotide (FAD) oxidoreductase. A C-terminally His-tagged fusion TftC used NADH to reduce either FAD or flavin mononucleotide (FMN) but did not use NADPH or riboflavin as a substrate. Kinetic and binding property analysis showed that FAD was a better substrate than FMN. TftD was a reduced FAD (FADH(2))-utilizing monooxygenase, and FADH(2) was supplied by TftC. It converted 2,4,5-trichlorophenol to 2,5-dichloro-p-quinol and then to 5-chlorohydroxyquinol but converted 2,4,6-trichlorophenol only to 2,6-dichloro-p-quinol as the final product. TftD interacted with FADH(2) and retarded its rapid oxidation by O(2). A spectrum of possible TftD-bound FAD-peroxide was identified, indicating that the peroxide is likely the active oxygen species attacking the aromatic substrates. The reclassification of the two enzymes further supports the new discovery of FADH(2)-utilizing enzymes, which have homologues in the domains Bacteria and Archaea.