干扰素研究进展

干扰素是一类具有广泛生物学活性的蛋白质,具有调节机体免疫功能、抗病毒、抗肿瘤等多种作用,是机体防御系统的重要组成部分。该文主要叙述了干扰素的分类基本特性,作用机理及其在人医和兽医上的应用,并指出了当前干扰素研究中存在的问题。     

Effect of dietary supplemental nicotinic acid on growth performance,carcass characteristics and meat quality in three genotypes of chicken

The effects of dietary supplemental nicotinic acid (NA) on growth performance, carcass characteristics and meat quality were investigated in three genotypes of chicken. Fast‐growing AA (Arbor Acres) broilers were compared with two genotypes of a slow‐growing local breed, Beijing‐You, that had undergone selection for and against intramuscular fat content respectively (BJY+IMF and BJY?IMF). The treatments were arranged 3 × 4 factorial completely randomized design. Day‐old females (n = 624) were allocated to four treatments with six replicates per treatment and fed diets (basal contained ～25 mg NA/kg) supplemented with 0, 30, 60 and 120 mg NA/kg. A sample of 72 birds from each genotype was slaughtered at market time (8 weeks of age for AA and 16 weeks of age for BJY). The breast muscles of AA broilers were darker, had less redness and yellowness, lower drip loss and higher shear force as compared to the BJY genotypes (p < 0.01). The highest drip loss and the lowest shear force among the three genotypes were apparent in BJY+IMF (p < 0.01). Increasing supplementation from 0 to 60 mg NA/kg tended to increase average daily gain (ADG), average daily feed intake, width of intermuscular fat band, thickness of subcutaneous fat (including skin) and percentage of abdominal fat but, for most variables, values decreased slightly with 120 mg NA/kg. Increasing supplementation to 60 mg NA/kg decreased (quadratic, p < 0.001) drip loss, but it increased at 120 mg NA/kg. The present results indicate that (i) the AA broilers fed corn–soybean meal based‐diets require approximately 60 mg NA/kg to maximize ADG and meat product yield and decrease the drip loss of breast muscle; (ii) the addition of 30 mg NA/kg meets the requirement of BJY genotypes; and (iii) there seems to be no beneficial effect of NA supplementation on chicken meat quality except for limiting the drip loss.     

藏族的草原游牧文化(Ⅱ)——藏区的草原和生产文化

青藏高原是全球海拔最高的自然地域单元,由于地势高耸、气候寒冷而被称之为“地球第三极”.它是南亚、东南亚众水发源地,哺育了中华黄河、长江流域文明和印度河流域文明.至当代,它仍然对中华民族乃至南亚、东南亚人民的生存和发展有着决定性影响.草原分为高寒草原、高寒草甸、荒漠草原、高寒灌丛等.在各类草地类型中,以高寒草原与草甸草地...     

基于ISSR分子标记的紫云英种质资源遗传多样性及结构分析

紫云英(Astragalus sinicus L.)是我国重要的稻田绿肥作物,为揭示不同地区种质资源遗传特征,本研究利用ISSR分子标记对77份紫云英种质资源进行了遗传多样性及结构分析。研究发现,77份供试紫云英种质资源遗传相似性系数为0.567 7～0.868 6,可划分为6个聚类。不同地区群体间分化系数为0.136 3,达到极显著水平(P<0.001),其中种群间变异占比13.9%,种群内变异占比86.1%。不同ISSR引物扩增信息鉴别紫云英资源的能力存在差异,构建了以P809第3,8,9,10,12,15扩增位点以及P886第1,3,5,9,10,11扩增位点为特征的指纹图谱,能有效区分77份供试紫云英资源。以资源所在省份为单元进行群体分析,供试紫云英资源遗传结构呈现分化特征,河南-安徽-江苏-上海资源遗传结构相似,构成北方亚群;四川-广西-湖南-江西资源相似,构成西南方亚群;福建种质资源则呈现混合型特征。本研究结果可为我国紫云英种质资源的科学利用及新品种选育提供依据。     

Direct impacts of recent climate warming on insect populations

Effects of recent climate change have already been detected in many species, and, in particular, in insects. The present paper reviews the key impacts of global warming on insect development and dispersal. The effects of climate change appear to be much more complex than a simple linear response to an average increase in temperature. They can differ between seasons and bioclimatic regions. Earlier flight periods, enhanced winter survival and acceleration of development rates are the major insect responses. Differential response of insects and hosts to warming up might also lead to disruption of their phenological synchrony, but adaptive genetic processes are likely to quickly restore this synchrony. In a number of cases, warming results in removing or relocating the barriers that limit present species' ranges. It is also likely to facilitate the establishment and spread of invasive alien species. Finally, knowledge gaps are identified and future research interests are suggested.     

Identification and Molecular Characteristics Analysis of Porcine Epidemic Diarrhea Virus Variants

To ascertain a diarrhea case in a pig farm in Shandong province,the pathological changes of dead piglets were observed and nested RT-PCR test was carried out on 7 diarrhea samples for porcine epidemic diarrhea virus (PEDV).Pathological examination revealed that intestine was detected as enlargement,hyperemia and edema.After histological examination,the typical microscopic lesions of intestine were disappearance of epithelial cells,villus shrinkage and shortening.The result of nested RT-PCR showed that all of the 7 samples could amplify a specific target band of PEDV.Molecular characteristics of two field strains showed that they had an amino acid homology of 92.3% to 92.4% with vaccine CV777 and 96.6% to 98.6% with other previous field strains which sequences were downloaded from GenBank.Phylogenetic tree analysis further revealed that all of PEDV strains could be mainly divided into two clusters of G1 and G2. G2 consisted of the field strains of our study and other field strains from USA,China and so on,which had the same sequence characteristics of two insertions and one deletion,while G1 consisted of all vaccines of CV777 and several older field strains from China and Korea.These results indicated that our field strains were the dominant strains in recent epidemic diarrhea occurrence.Moreover,its molecular characteristics might be a characterization of differentiating the field and vaccine strains.     

采煤沉陷区苦草的生物学特性及其竞争机制

采煤活动所致的动态沉陷湿地具有动态性、高潜水位和生态脆弱性等特点,探明此类人工重构湿地的水生植物群落的生物学特性及其竞争机制,有助于为采煤沉陷区湿地水生植物群落修复提供科学依据。本研究以淮南潘集区人工构建的苦草群落(Ass. Vallisneria natans)为例,采用样方调查法,研究苦草的生物学特性及其与其他水生植物的竞争机制。结果表明,1)沉陷区苦草的生物学特性与浅水湖泊较一致。主要表现在苦草的繁殖方式、传粉方式、生活史方面,但研究区苦草以有性繁殖为主。2)沉陷区苦草能与以种子萌发形成的水烛群丛(Ass. Typha angustifolia)共生,但生物量低;在与形成两年以上的水烛群丛竞争中处于劣势,在水烛群丛盖度达到90%时苦草逐渐消失。3)沉陷区苦草在与浮叶植物莕菜群丛(Ass. Nymphoides peltatum)、苹群丛(Ass. Marsilea quadrifolia)竞争中处于弱势,其盖度、株高、生物量等指标都明显下降。4)沉陷区苦草在与沉水植物竹叶眼子菜群丛(Ass. Potamogeton malaianus)竞争中处于劣势,苦草与沉水植物黑藻群丛(Ass. Hydrilla verticillata)、狐尾藻群丛(Ass. Myriophyllum verticillatum)、大茨藻群丛(Ass. Najas marina)、金鱼藻群丛(Ass. Ceratophyllum demersum)占据不同水层空间,种间竞争不强烈,能较好地共存。总之,苦草较之于相似生长型的植物具有较明显的竞争优势,对于具有不同生活型,尤其是挺水植物和浮叶植物,处于竞争劣势。     

青南高原气候变化及其对高寒草甸牧草生长影响的研究

通过对１９６１年以来青南高原气候变化的分析,发现该地区年平均降水量及秋季降水量无明显的变化趋势,且其年际间的波动趋于缓和;冬季（１２－２月）和春季（３－５月）降水量的变化趋势呈现出逐年增多的趋势,气候倾向率分别为２．６ｍｍ／１０ａ和３．６ｍｍ／１０ａ;夏季降水量变化却表现出显著的减少趋势,其倾向率为－６．５ｍｍ／１０ｓ。     

次黄筒天牛生物学特性及卵的空间分布研究

次黄筒天牛在江苏太仓1～2年发生一代，幼虫在枝干内越冬，成虫6月上旬～7月中旬羽化，取食桑树的嫩叶、叶脉，产卵于桑树新梢端部。卵期13d，幼虫蛀入枝条，先向上蛀食到梢端再调头向下蛀食，枝条短的幼虫可入拳越冬，第2年5月中旬化蛹，蛹期约16d。被害株有效条数降低，影响产叶量。该虫卵的空间分布为聚集型。个体间相互吸引但聚集强度不高，并在此基础上提出了序贯抽样模型。     

利用根管法对油菜和冬小麦苗期根系形态的研究

快速、准确的根系原位观测方法是根系研究中的重要技术,本研究介绍了一种根管盆栽方法,该方法在透明PVC管内种植作物,通过遮光膜保持管内黑暗环境,以实现在作物生长过程中对其根系生长的原位动态观测,且根系生长环境更接近田间实际情况,并可通过改变根管长度、半径等将其应用于田间深根作物的研究中。利用此方法、结合根系扫描技术分析了油菜和冬小麦从发芽到出苗后16 d时的根系生长情况。结果表明,出苗后7和16 d冬小麦根系和地上部干物重均大于油菜,出苗后16 d冬小麦和油菜根冠比分别为0.513和0.372。大部分根系分布在0~16 cm表层土壤中,出苗后16 d冬小麦和油菜表层土壤中的根长在总根长中的比例分别为62.60%和67.76%,根系总表面积、总体积和一级侧根数均为表层土壤中占比最多,在出苗后7 d,总根长、总表面积、总体积和一级侧根数均为冬小麦显著高于油菜,而在出苗后16 d,两种作物的总根长和总表面积差别不大,说明油菜根系生长呈先缓后快趋势。表层土壤中根系平均直径小于底层土壤,油菜根系平均直径小于冬小麦,油菜和冬小麦的根系直径均大部分在0~0.50 mm之间,随着根系生长,较细的侧根逐渐增多,根系平均直径变小。出苗后16 d内的冬小麦根系伸长速率为1.83 cm/d,大于油菜的1.51 cm/d。因此,冬小麦苗期根系生长快于油菜,油菜根系呈先缓后快的生长特性。本研究介绍的根管法是一种原位研究根系的有效方法。