奶牛分子育种专题学习网站的建设构想

阐述了建设奶牛分子育种专题学习网站的意义和构想,规划了网站的主要内容和发展方向,为相关专业的研究者和从业人员提供参考。     

鸡,鸭体内传染性法氏囊病病毒的分离及理化性质比较

从疑似传染性法氏囊病（ＩＢＤ）病鸡及同群饲养的鸭体内各分离到１株病毒，用传染性法氏囊病病毒（ＩＢＤＶ）单克隆抗体夹心ＥＬＩＳＡ试验证明两病毒均为ＩＢＤＶ，病毒血清型为Ⅰ型。病毒可致死鸡胚，适应于鸡胚成纤维细胞并产生细胞病变（ＣＰＥ）。理化性质比较表明，两病毒为同源ＩＢＤＶ。研究表明，鸭可成为ＩＢＤＶ的携带者或传染源。     

Use of computed tomography to evaluate pathologic changes in the lungs of calves with experimentally induced respiratory tract disease

OBJECTIVE: To optimize methods for the use of computed tomography (CT) to assess pathologic changes in the lungs of calves and to determine the effect of treatment on lung consolidation. ANIMALS: 10 male Holstein calves. PROCEDURES: Calves were anesthetized to facilitate CT imaging of the thorax. After initial images were obtained, pneumonia was induced in the calves by inoculation through a bronchoscope. Two calves were used in a preliminary study to refine the inoculation dose and optimize CT images. Four calves were administered florfenicol and 4 calves were untreated control animals. Serial images were obtained 24, 48, and 72 hours after inoculation. After final images were obtained, calves were euthanized, and lung consolidation was estimated by use of lung surface area scoring and water displacement. These estimates were compared with estimated lung consolidation obtained by use of CT. RESULTS: Calves had rapid disease progression. Percentage of lung consolidation was not significantly different between treatment groups for any of the estimation methods. Results of an ANOVA of the 3 assessment methods indicated significant differences among methods. Estimates of the percentage of lung consolidation obtained by use of surface area scoring and CT correlated well, whereas water displacement estimates correlated poorly with other methods of consolidation estimation. CONCLUSIONS AND CLINICAL RELEVANCE: Because of the correlation with other methods for estimation of lung consolidation, CT has the potential to be used to monitor disease progression in calves with experimentally induced respiratory tract disease.     

种子的发芽和休眠(Ⅰ)

种子是粮食的重要组成部分.仅禾本科作物的谷粒(约占栽培作物种子产量的90%),就占全球粮食产量的一半.因此,勿庸置疑,种子生物学是植物生理学的主要研究分支之一.在Agricola资料库中,最近10年收集的发芽方面的文章有5 000多篇,休眠方面的文章有700多篇.     

壳聚糖浸种对干旱胁迫下苜蓿种子发芽的缓解作用

以苜蓿种子为试材,采用不同浓度壳聚糖溶液对苜蓿进行浸种处理,测定其对干旱胁迫下苜蓿种子发芽和幼苗生长的影响,旨在寻找苜蓿发芽阶段抗干旱胁迫的最佳浸种浓度。结果表明:随着壳聚糖溶液处理浓度的升高,干旱胁迫下苜蓿种子发芽率、发芽势、发芽指数、活力指数、苗高与根长均呈现先上升后下降的趋势。隶属函数综合分析表明,壳聚糖溶液浸种对干旱胁迫下苜蓿种子发芽能力的影响效果由大到小依次为:100 mg/L、50 mg/L、25 mg/L、150 mg/L、0 mg/L、200 mg/L,以100 mg/L的壳聚糖浸种处理对提高苜蓿种子发芽阶段抗干旱胁迫的效果最佳。     

Biodiversity of mannose-specific lectins within Narcissus species

Mannose-specific lectins (MSLs) were isolated from the bulbs of 27 species of wild Spanish Narcissi and compared to the commercially available MSL from daffodil (Narcissus pseudonarcissus, NPA). Molecular weight analysis showed the monomers of all the MSLs were at, or around, 12.5 kD. Haemagglutination assays showed that the MSLs exhibited activities at up to four times greater than that displayed by NPA and other MSLs derived from other species such as Galanthus nivalus (snowdrop) and Allium ursinum (ramson). Elution profiles from ion exchange chromatography exhibited similarities for species within the same taxonomic section suggesting that this method could aid in species classification. Further analysis by isoelectric focusing showed many isolectins are present in vivo and that even within a single peak from ion exchange chromatography there are numerous isolectins present. The basis of the isolectin heterogeneity is suggested to reside in the tetraploidy (sometime triploidy) nature of Narcissus genes.     

Changes to a soil on irrigation with a sanitary landfill leachate

A detailed soil column leaching experiment was set up to investigate the changes in properties to a soil as a result of irrigation with an alkaline sanitary landfill leachate (pH 10.3). Chemistry of the soil was drastically altered as a consequence of the interaction. The soil was titrated from pH 5 to pH 10 and was changed from an exchangeable Mg dominated soil to an exchangeable Ca dominated soil. Magnesium was displaced by ion exchange reaction at acid pH, but at pH 10, 14.2 meq 100 g^?1 of Mg, i.e. up to three times the cation exchange capacity of Mg, was adsorbed in non-exchangeable forms at the immediate surface of the soil column by specific adsorption reactions. The leachate-treated soil was not stable on distilled water leaching. Structural breakdown led to clay dispersion and reduction in pore space, resulting in a 64 times reduction in hydraulic conductivity, 1.6 × 10^?4 to 2.5 × 10^?6 cm s^?1. The structural breakdown could be explained in term of the increase in Na adsorption ratio of the treated soil and the subsequent reduction in electrolyte concentration following the distilled water treatment.     

Can the arbuscular mycorrhizal fungus Glomus intraradices actively mobilize P from rock phosphates?

Plants colonized by arbuscular mycorrhizal (AM) fungi have been shown to respond positively to the application of insoluble forms of inorganic phosphorus (P) such as rock phosphates (RPs). The mechanism(s) underlying such responses remain(s) unknown and although it has been hypothesized, there is no experimental support for the production of chelating agents by AM fungal hyphae. Here we investigate whether AM fungi can solubilize P from RPs and transfer it to plant roots. Using root-organ cultures of Daucus carrota L. inoculated or not with Glomus intraradices Schenk & Smith and containing P from different RP sources, we predicted that: (1) roots inoculated with G. intraradices would take up more P than those uninoculated; that (2) the amount of P taken up by roots through G. intraradices would be positively correlated with the RP reactivity; and that (3) G. intraradices would have access to RP through localized alterations of pH and/or by the production of organic acid anions that may act as chelating agents. The RP reactivity was positively correlated with P uptake. However, mycorrhizal roots grew initially slower and did not respond differently to any P treatment than those uninoculated. There was no evidence of localized changes in pH in proximity of G. intraradices hyphae, indicating that responses to RP by mycorrhizal plants observed in previous studies do not appear to result from the release of H⁺ ions alone or in combination with organic acid anions.