草鱼出血病病毒对其它鱼的感染性研究

用草鱼出血病病鱼分离出的草鱼出血病病毒(Grass carp hemorrhage virus,GCHV)感染其它常见鱼并用ELISA方法检查感染鱼组织提取液,结果表明:青鱼、鲢鱼、布氏鳌条对GCHV抗体呈阳性反应;鲤鱼、鳙鱼、鲫鱼、团头鲂、泥鳅则呈阴性反应。综合感染鱼发病症状及死亡特征,初步认为:青鱼对GCHV是易感的,GCHV能在鲢鱼、布氏蟹条体内增值,但毒力较低,鳙鱼、鲫鱼、团头鲂、鲤鱼、泥鳅能抗GCHV感染。     

酶标HBV DNA探针的研制与应用

本实验采用一种非放射性物质——碱性磷酸酶标记乙肝病毒HBV DNA制备分子探针。碱性磷酸酶在苯醌作用下与单链DNA联结,形成DNA和酶的共价复合物,即酶标探针。此探针通过分子杂交与待测DNA结合,与酶的底物作用显色,几小时内可观察结果,其最低检测量约为10pg。用此探针检测乙肝病人血清中的HBV DNA,与~(32)P标记的探针比较,酶标探针可检测出~(32)P标记探针检出率的95.7％。结果表明,所合成的酶标探针具有准确、简便、快速、安全而经济的优点,具有应用前景。     

东北主要造林树种的营养元素含量特征分析

 本文分析测定了东北地区9个主要针阔叶树种的营养元素含量和季节动态,并应用主成分分析和系统聚类分析方法,分析了各树种之间的营养元素相互关系。从而证明了N,P,Ca是植物重要的临界营养元素,Fe和Mn是表土中高度积累元素,树木对前者的吸收与土壤表土中含量有关,而对后者则表现相对的独立性和选择吸收能力。从营养元素的吸收与利用角度考虑,红松与胡桃楸混交,落叶松与水曲柳混交,硬阔叶树与软阔叶树混交,针阔叶树之间混交或白桦与其它各树种混交都是合理的。     

腐蹄病致病因子节瘤拟杆菌蛋白酶在大肠杆菌...

Bacteroides nodosus is the essential causative agent of ovine footrot. It produces extracellular proteases which involved in pathogenesis of footrot. In this paper, we report the subcloning of Bacteroides nodosus protease, its overexpression in E. coli and its N-terminal polypeptide sequence. The subclone library was constructed in E. coli using SphI digested original clone (15 kb) and plasmid PTZ18R and screened using immunological assay. The expression was observed using SDS-PAGE. The subcloned DNA fragment was then cut with Sau3AI, cloned into pKK232-8 vector to perform promoter isolation and analysis. The promoter strength was determined using spectrophotometric assay.     

Synthesis and structure-activity study of myxoma virus growth factor

Myxoma virus growth factor (MGF) is an 85-residue peptide derived from the gene product of a DNA tumor virus that infects rabbits. The carboxyl domain of MGF possesses about 40% sequence homology with the epidermal growth factor (EGF). This EGF-like domain covering residues 30-83 was synthesized and found to possess putative activities of EGF. It was, however, about 200-fold less active than EGF in the competitive binding of EGF receptor in A431 cells and the stimulation of [3H]-thymidine uptake in NRK 49F cells. MGF(30-83) is a basic and a hydrophobic peptide rich in beta-sheet structure. These features in MGF tend to promote aggregation, leading to precipitation even in strongly denaturing solutions. Thus, the refolding of MGF was achieved with difficulty and resulted in low yield. To increase the synthetic yield of MGF(30-83), a cluster of acidic amino acids was added to the NH2-terminus of MGF(30-83). This approach was found to be effective in minimizing the refolding difficulties and allowed accessibility to the synthesis of analogues in this class of compounds. The relationships of structure and function of MGF were studied by using analogues with point substitution by the corresponding D-amino acid or by Ala at position 44 or 52 and analogues with deletion of basic residues from the amino terminus. Modifications of both the receptor contact and the structural residues greatly reduced the potency of MGF(30-83), and the overall result correlated well with the known structure-activity of the EGF family.     

Modulation of hepatic level of microsomal testosterone 7 alpha-hydroxylase, P-450a (P450IIA), by thyroid hormone and growth hormone in rat liver

The effects of thyroid hormone and growth hormone on microsomal testosterone 7 alpha-hydroxylase, P-450a, were studied to understand the interaction of these hormone-mediated regulations in rats. In Western blots using anti-P-450a IgG, 1.7-fold higher content of P-450a was observed in livers of female than male adult rats, while no appreciable sex-related difference was detected in prepubertal rats and rats of 24 months of age. Treatment with n-propyl-2-thiouracil or thyroidectomy of male rats increased by 2-fold the hepatic content of P-450a, but neither regimen had a significant effect on the content in female rats. Levels of P-450a in both sexes of thyroidectomized rats were decreased by the supplementation of triiodothyronine (T3, 50 micrograms per kg, i.p. for 7 days) to levels similar to that observed in normal male rats. Hypophysectomy also caused an increase in microsomal P-450a content in male rats. Continuous infusion of human growth hormone, which mimicked the female secretion, further significantly increased the content in hypophysectomized rats to a level similar to that observed in normal female rats. In contrast, hepatic level of P-450a in hypophysectomized male and female rats was reduced by intermittent injection, which mimicked the male secretion. Clear suppression on the level of hepatic P-450a was also observed by the treatment of hypophysectomized rats with 5 or 50 micrograms/kg of T3 and of hGH-infused hypophysectomized rat with 50 micrograms/kg of T3.(ABSTRACT TRUNCATED AT 250 WORDS)     

Cytostatic and growth-stimulating effects of alveolar macrophages of rats on tumor cells

Cytostatic and growth-stimulating effects of alveolar macrophages (AM) of rats on tumor cells were studied. The experimental results are summarized as follows. 1. The cytotoxicity of AM activated with BCG to tumor cells was increasing with the increase of effector cells/target cells (E/T) ratio. AM without the treatment with BCG expressed slight cytotoxicity to tumor cells at a high E/T, and growth-stimulating effect on tumor cells, at a low E/T. 2. AM after 24-hour culture had a lower manifestation of cytotoxicity to human lung adenocarcinoma cell line than that of AM without 24-hour culture, and had a growth-stimulating effect on B-16 cell line. 3. Cytostatic and growth-stimulating effects of AM without or with 24-hour culture were decreasing with the increase of irradiation doses.