动物病毒受体阻断剂的研究进展

病毒进入宿主机体后,病毒粘附蛋白(VAP)首先与宿主靶细胞膜特异受体结合,被吸附到宿主敏感细胞上,然后通过膜融合等方式侵入细胞中,完成脱囊膜或脱壳并进行复制、转录及装配等增殖过程。许多研究通过不同的途径试图寻找可以阻断病毒吸附的抑制剂,已取得了重要进展。近年来国内外文献表明,硫酸乙酰肝素(HS)是细胞膜上许多病毒的特异受体或者辅助受体,用一些可溶性的肝素,如肝素钠、硫酸软骨素可以特异阻断病毒的吸附和侵入。另外,具有糖结合活性的植物凝集素及一些糖类衍生物可以与细胞膜上的某些病毒特异受体糖蛋白结合,从而不同程度地抑制病毒和宿主细胞的结合。本文对该领域研究成果作一综述,旨在为今后对水产动物病毒阻断剂的研究提供参考。     

Seasonal changes in cortisol sensitivity and glucocorticoid receptor affinity and number in leukocytes of coho salmon

To determine if there were organ-specific changes in immune responses or immune-endocrine interaction, we monitored in vitro immune response, cortisol sensitivity and number and affinity of glucocorticoid receptors (GR) in leukocytes from freshwater-adapted juvenile coho salmon (Oncorhynchus kisutch) during the physiological changes that prepare them to enter the marine environment. During this period, absolute immune response declined, but splenic leukocytes generated more antibody-producing cells than did cells from anterior kidney. Splenic leukocytes were initially more sensitive to the suppressive effects of cortisol and had fewer GR than leukocytes from the anterior kidney. Leukocytes from the anterior kidney were initially insensitive to cortisol but developed sensitivity at about the same time as the dissociation constant and number of GR increased. In vitro incubation of anterior kidney leukocytes in cortisol altered GR variables when experiments were conducted during March through September but not during November through February. In some years, changes in GR or immune responses were correlated with plasma cortisol titers, but in other years there was no correlation. Thus, the exact relation between cortisol, GR and immune response in anadromous salmonids is unclear and other factors are involved.     

Pituitary gonadotropin-releasing hormone (GnRH) receptor activity in goldfish and catfish: seasonal and gonadal effects

The goldfish pituitary contains two classes of gonadotropin-releasing hormone (GnRH) binding sites, a high affinity/low capacity site and a low affinity/high capacity site (Habibiet al. 1987a), whereas the catfish pituitary contains a single class of high affinity GnRH binding sites (De Leeuwet al. 1988a). Seasonal variations in pituitary GnRH receptor binding parameters, and the effect of castration on pituitary GnRH receptor binding were investigated in goldfish and catfish, respectively. In goldfish, GnRH receptors undergo seasonal variation with the highest pituitary content of both high and low affinity sites occurring during the late stages of gonadal recrudescence. The observed changes in pituitary GnRH receptor content correlate closely with responsiveness to a GnRH agonistin vivo in terms of serum gonadotropin (GTH) levels. In catfish, castration results in a two-fold increase in pituitary GnRH receptor content, which can be reversed by concomitant treatment with androstenedione, but not by the non-aromatizable androgen 11β-hydroxyandrostenedione; changes observed in GnRH receptor content correlate with variations in serum GTH levels and responsiveness to a GnRH agonist. In summary, the present study provides a clear evidence for seasonal variation in pituitary GnRH receptor activity in goldfish, and demonstrates a gonadal feedback mechanism regulating GnRH receptor activity in the catfish pituitary.     

孕激素受体在雌性山羊颈动脉体的分布

为了证实孕激素受体是否存在于雌性山羊颈动脉体。取雌性山羊的颈动脉体,经免疫组织化学SP法染色后,观察孕激素受体在颈动脉体的分布特点。结果表明,在雌性山羊的颈动脉体的Ⅰ型细胞、Ⅱ型细胞、血管内皮细胞均有不同程度的阳性染色。Ⅰ型细胞中PR强阳性产物分布于细胞膜,中等阳性产物分布于整个细胞质中;Ⅱ型细胞和血管内皮细胞有强阳性产物分布。证实孕激素受体在雌性山羊颈动脉体中分布广泛,提示颈动脉体可能接受孕激素的调节,这为研究孕激素非生殖调节功能及颈动脉体的神经内分泌调节机制提供了形态学依据。     

基于电性距离矢量预测新烟碱类杀虫剂的生物活性研究

基于电性距离矢量理论,计算20种重氮乙烷新烟碱类杀虫剂分子的拓扑指数（mk）,经最佳变量子集回归方法建立四元和三元数学模型,并采用逐一法交互检验（R2-cv）、F、A。F-IC、tα/2对所建模型进行检验。结果表明,所建2个QSAR模型具有良好的泛化能力及预测能力,p％_D和pK_A模型的判定系数（R-2）分别为0.955和0．988,R2-cv依次为0．929和0．980;根据pK-D的QSAR模型建议重氮乙烷新烟碱类分子可能的杀虫机理;在影响重氮乙烷新烟碱类化合物作用于果蝇nAChRs的亲和力中-N-、-0基团起到主要及正向作用,而在影响哺乳动物α4β2亚型受体的亲和力中-C-、〉C一更重要且为负向作用。     

Selection for imidacloprid resistance in Nilaparvata lugens: cross-resistance patterns and possible mechanisms

A field population of brown planthoppers (Nilaparvata lugens St?l) was collected and selected for imidacloprid resistance in the laboratory. The resistance increased by 11.35 times in 25 generations and the resistance ratio reached 72.83 compared with a laboratory susceptible strain. The selected resistant strain showed obvious cross-resistance to all the acetylcholine receptor targeting insecticides tested (monosultap 1.44-fold, acetamiprid 1.61-fold, imidacloprid homologues JS599 2.46-fold and JS598 3.17-fold), but not to others. Further study demonstrated that TPP and DEM had no synergism on imidacloprid. However, PBO displayed significant synergism in some different strains, and the synergism increased with resistance (S strain 1.20, field population 1.43 and R strain 2.93). PBO synergism to cross-resistant insecticides was also found in the resistant strain (monosultap 1.25, acetamiprid 1.39, JS598 1.94 and JS599 2.02). We concluded that esterase and glutathione S-transferase play little role in imidacloprid detoxification. The increase of the P450-monooxygenases detoxification is an important mechanism for imidacloprid resistance and target resistance may also exist in this species.     

Advances in the expression of killer cell inhibitory receptors by T cells

Only in recent years, attentions have been drawn to the significance of expressing killer cell inhibitory receptors (KIR) in T cells KIRs specifical y bind to the corresponding region of the MHC class Imolecules and transmit negative signals to prevent cytotoxity of T cells. When the ligands of KIRs are missing, the lysis of the target cells can't be avoided.Perhaps the existence of KIRs is the main mechanism for preventing T cells from attacking autologous tissues. The recognition mechanism of the interaction between the KIR⁺ donor T cells and the recipient's MHC class I molecule expressing tissue cel s might shed light on the establishment of the immunotolerance for the prevention of allo-graft reject ion and graft-versus-host disease.