野外放归大熊猫肠道菌群变化的研究

对四川卧龙中国保护大熊猫研究中心的一只野外放归亚成体大熊猫肠道菌群的组成和季节变化规律进行了研究,同时与其圈养双胞胎兄弟的肠道菌群进行了比较。从放归大熊猫粪便中分离出17种肠道菌,优势菌群为肠杆菌、肠球菌和乳杆菌。与圈养大熊猫相比,放归大熊猫肠道菌群中优势菌群的种类未发生改变,但是肠球菌数量增加,肠杆菌和乳杆菌的数量减少。研究发现放归大熊猫肠道菌群中的肠杆菌和肠球菌的数量随季节变化有较大波动,乳杆菌的数量随季节变化波动不大;而圈养大熊猫三种优势菌的数量随季节变化波动都不大。     

五种市售鸡传染性鼻炎灭活疫苗免疫效力比较

本研究对国内市场上几个主要鸡传染性鼻炎灭活疫苗生产厂家生产的灭活疫苗免疫鸡只进行血清HI抗体水平测定和攻毒,比较不同公司所产疫苗效力的效力差异,并评估A、C型二价灭活疫苗两次免疫鸡群对国内B型分离株:DL-1株和最近从免疫失败鸡场分离到的SD-1株的交叉保护作用,分析免疫失败的原因.结果表明:A、D、E公司的疫苗免疫两次后,A型HI抗体阳性率分别为92.5%、100%和95%,滴度分别为33.9、55.1和59.9,攻毒保护率都是100%.C型HI抗体阳性率分别为72.5%、38.5%和77.5%,滴度分别为11.4、2.7和27,攻毒保护率分别为80%、70%和80%.而B和C公司的疫苗免疫两次后A型HI抗体阳性率分别为59.4%、77.1%,抗体滴度分别为5.4和21.8,攻毒保护率分别为50%和66.7%;C型HI抗体阳性率分别为54.1%和51.4%,抗体滴度分别为6.1和6.8,攻毒保护率分别为38.3%和50%.在五个疫苗产品中,以A、D、E的保护效力较好,B、C产品效力较差.另外,A、C型二价灭活疫苗免疫后不能对B型菌的攻击提供保护,其A、C型HI抗体阳性率、抗体滴度与对B型菌攻毒保护率无相关性.     

Fine structure and invasive behaviour of the early developmental stages of Theileria annulata in vitro

The interaction, in vitro, between bovine peripheral blood lymphocytes and sporozoites of Theileria annulata (Ankara) was studied by light and electron microscopy. Beginning five minutes following incubation, samples were taken for Giemsa-stained smears and glutaraldehyde-fixed pellets, for light and electron microscopy, respectively. Sporozoites of T. annulata measure an average of 0.9 microns long, 0.8 microns broad and possess a limiting unit membrane, the pellicle; a round-to-ovoid, eccentrically situated, non-chromocentric nucleus; double-membraned, tubular, acristate mitochondria; varying numbers of anisocytic, densely osmiophilic and pleomorphic organelles, the rhoptries which together with the polar ring form the apical complex; and numerous, loosely scattered, electron-dense ribosomal particles. As early as 5 min of incubation, sporozoites had made contact with, and penetrated, lymphocytes. Sporozoites consistently attached to the lymphocyte plasmalemma by their basal end, possibly at specific receptor sites. Apparently only a proportion of lymphocytes (up to 40% and more commonly 10-20%) were susceptible. Two subpopulations of the susceptible lymphocytes were observed; one which appeared to have receptor sites localized on one pole of the plasmalemma and the other subpopulation in which the receptor sites were distributed evenly around the plasmalemmal surface. Within individual susceptible lymphocytes, the number of interiorized sporozoites increased from 1 to 3 at 5-10 min to as many as 15 or more parasites at around 60 min of incubation. Theileria annulata sporozoites were interiorized by the invagination of the host cell plasmalemma which remained intact throughout the process but later fragmented. Within 30 min of interiorization, each sporozoite underwent dedifferentiation by the loss of its rhoptries and transformed into a trophozoite. Around 24 h, the trophozoite, a uninucleate, motile and feeding stage of the parasite, developed into a schizont by an acentric, closed mitosis.     

In vitro properties of diffuse cytoplasmic esterase-positive canine mononuclear leukocytes

Depletion of cytoplasmic esterase-positive canine peripheral blood monocytes from mononuclear cell suspensions was attempted using plastic adherence, carbonyl iron ingestion and/or Sephadex G-10 filtration. An esterase-positive, nonadherent, nonphagocytic subpopulation was identified and further characterized by the presence or absence of cell membrane receptors for the Fc portions of immunoglobulin and the activated third component of complement. The majority of these nonadherent cells lacked these receptors. The data suggests that canine peripheral blood monocytes are a heterogenous cell population.     

高钙日粮对蛋鸡生产性能及出壳雏体内锌含量的影响

生长期日粮钙>3.11%,可使蛋鸡性成熟期明显延缓,开产日龄推迟;其蛋锌及子代出壳雏血锌和多数组织锌含量明显降低,但胚胎及出壳雏鸡未见畸变.出壳雏血锌含量能反映体内锌状态,可作为其评价指标.产蛋期高钙(6.11%)或低钙(0.83%)日粮均可使产蛋性能及孵化率降低.     

蜂胶抗菌效果影响的研究

以乙醇浸出提取的蜂胶和CO2超临界萃取提取的蜂胶为材料,测定了两种蜂胶的效果和最低抑菌浓度。结果表明:两种蜂胶对大肠埃希氏杆菌、枯草杆菌、金黄色葡萄球菌、白念珠菌和紫色癣菌都有一定抑菌效果,最低抑菌浓度为1.54～3.08mg/mL。     

松嫩平原羊草草地水淹干扰恢复过程的群落动态

根据随机取样的测定数据，经过幂函数和多元回归分析及相关检验，揭示了草地水淹干扰对羊草 寸草苔、羊草 杂类草群范数量性状的变化规律。水淹干扰对草地植被的物种组成及其比例有明显的影响。水淹后基本恢复到正常草地的种类数量和生产量配置大约需要6—7年。随着生境水分减少和土壤变干，羊草种群的数量和生物量均以幂函数形式增加，而寸草苔和杂类草的数量和生物量则呈先增后降的变化过程。     

Weed-Suppressive Bacteria Applied as a Spray or Seed Mixture Did Not Control Bromus tectorum

We conducted two case studies testing effectiveness of a soil-borne bacteria, Pseudomonas fluorescens strain D7, in controlling Bromus tectorum (cheatgrass) when mixed with native seeds sown after a fire and when sprayed on a native community with high abundances of B. tectorum. Each case study area (162 ha) compared treatments with D7 present and absent and was replicated four times (20.3 ha each) in a completely randomized design. Response variables (foliar cover, aboveground biomass, and density of B. tectorum; density of sown native plants) were measured pretreatment for the sprayed area and each year for 3 yr after treatment at both study areas and were evaluated as a repeated measures analysis. Foliar cover, biomass, and density of B. tectorum with sprayed or seed mixture applications did not differ between D7-treated and untreated areas at any time within the study (F_1,6 ≤ 1.42; P ≥ 0.28). D7 as a seed mixture did not significantly impact densities of native seedlings (F_1,6 = 1.27; P = 0.30) at any time during the study. Results contrasted with previous D7 studies that showed effective control of B. tectorum within 3 yr of treatment. Since bioherbicidal methods are being commonly applied, we believe that reporting negative results is important for future meta-analytical studies that provide managers with information on the likelihood for weed-suppressive bacteria to effectively control weeds.     

In growing pigs, chlortetracycline induces a reversible green bone discoloration and a persistent increase of bone mineral density dependent of dosing regimen

We studied in growing pigs the effects of exposure to dietary chlortetracycline on bone mineral density (BMD) and bone color. Pigs were randomly allocated to a drug-free diet (n = 48) or a diet fortified with 800 ppm of chlortetracycline, starting either at 28- or 84-d of age, and for either a 28- or 56-d duration (n = 16 pigs/group). The lumbar vertebral discoloration and BMD of randomly chosen pigs were evaluated at 28-d intervals up to 168-d of age. The odds of bone discoloration increased with dosing duration and age at treatment onset, and decreased with the withdrawal time and age at treatment onset interaction (p ? 0.001). The measured trabecular BMD linearly increased with age and squared treatment duration (p ? 0.005). Therefore, TC-induced bone discoloration is reversible, and may be prevented with proper dosing regimen design. Moreover, TC induces a persistent increase on BMD that could be detected with quantitative computed tomography.     

降水对青海同德高寒草地牧草产量影响的积分回归分析

利用积分回归的基本原理,并以青海省同德县巴滩高寒草地牧草产量为例,运用积分回归分析气象要素与牧草产量的关系,确定了青海省同德县巴滩高寒草地不同生育时段的降水对牧草产量的影响效应。结果表明,降水对高寒天然草地牧草产量的影响正效应为4月上中旬、5月下旬—7月上旬和8月下旬3个阶段,降水量每增加1mm,牧草产量最大增加138.2,80.1,53.8kg/hm2;负效应为4月下旬—5月中旬和7月中旬—8月中旬2个阶段,降水量每增加1mm,牧草产量相应最多减少23.1,43.7kg/hm2。