酸性水和投加铝、钙对鲢鱼早期发育和鳃超微结构的影响

在实验室条件下,研究了酸性水和投加铝、钙对鲢鱼胚胎孵化和鱼苗存活以及幼鱼鳃超微结构的影响。pH4.0引起所有胚胎在24小时内死亡,暴露于pH4.5—6.0的胚胎孵化率和暴露于pH4.0—6.0的5—15日龄鱼苗存活率随pH值上升而增高。投加0.5mg Al~(3+)/L使在酸性pH暴露条件下的胚胎孵化率和鱼苗存活率进一步降低。投加3.0mg Ca~(2+)/L可显著提高暴露于pH4.5和5.0的胚胎孵化率;投加2.0mg Ca~(2+)/L可在一定程度上提高暴露于pH4.5和5.0的鱼苗存活率。幼苗经pH4.5暴露8小时后出现严重的鳃超微结构损害;投加1.0mg Al~(3+)/L使鳃结构损害加剧;投加5.0mg Ca~(2+)/L可明显缓解酸性水对鳃的损害。     

利用普通怯寄蝇防治菜粉蝶初探

1 前言 从外地引进寄蝇或人工助长当地寄蝇种类防治农林害虫,是有效的生防手段之一,国外已有很多成功的报道。King等(1981)在路易斯安娜州蔗田中人工大量释放螟利索寄蝇(Lixophaga diatraeae)成虫防治第1代小蔗杆草螟(Diatraea saccharalis),不同地区的寄生率分别达到4.1、8.7和35.7％;由于降低了农药的使用量,奇痣窄径茧蜂(Agathis stigmatera)的自然寄生率也相应提高,很好地控制了蔗田害虫的发生。在寄蝇的田间释放技术方面,国外还没有详细的报道。在我国,利用寄蝇防治害虫的工作也是刚刚起步,很多具体问题有待于进一步研究。     

烙铁头蛇毒纤维蛋白原溶酶研究 Ⅰ分离纯化及理化性质(英文)

通过DEAE-SephadexA-50,DEAE-SepharoseCL-6B,MonoQ （FPLC）三步离子交换柱层析,纯化得到一新的纤维蛋白原溶酶,在碱性聚丙烯酰胺凝胶电泳和SDS-聚丙烯酰胺凝胶电泳上均呈单一的蛋白带。分子量为2600,等电点pl4.7;它是一个糖蛋白,含糖量6.4%,其中中性糖0.3%,已糖胺4.9%,唾液酸1.2%。烙铁头蛇毒纤维蛋白原溶酶TMVFg由187个氨基酸组成,含有较高的酸性氨基酸,此外甘氨酸含量也较高。TMVFg热稳定性强,而酸不稳定,在280 nm处具有典型的蛋白吸收峰,在无离子水中紫外消光系数E0.1%/280 nm=1.558。纯化的TMVFg具有较强的精氨酸酯酶活力,对苯甲酰-L-精氨酸乙酯（BAEE）的Km值为1.4×10[-3]M。TMVFg的活性受苯甲基丹磺酰氟（PMSF）抑制;乙二胺四乙酸（EDTA）对活性无影响。TMVFg不能使纤维蛋白原凝固,但能水解纤维蛋白原α、β链。纤溶实验表明TMVFg具有激活纤溶作用。纯化的烙铁头蛇毒纤维蛋白原溶酶对酪蛋白无作用,无出血活性,因而与凝血酶样酶、出血毒素及β-纤维蛋白原溶酶（OUYANG et al.,1977）明显不同。     

Interleukin—1β对促卵泡生成素（FSH）诱导大鼠...

Interleukin-1 beta (IL-1 beta), one of the polypeptide lymphokines released in response to antigen, toxins, injury or inflammation by nearly all cell types, has multiple systemic effects. In the present study the effect of IL-1 beta on follicle stimulating hormone (FSH)-induced estrogen production in primary culture was investigated. Granulosa cells obtained from immature estrogen-treated female rats were cultured for 3 days with increasing doses of FSH (1-30 ng/ml) with or without increasing doses of IL-1 beta (2-20 U/ml). The FSH stimulated estrogen production is dose-dependent, whereas IL-1 beta alone did not affect estrogen biosynthesis. In contrast, simultaneous treatment with IL-1 beta caused a dose-dependent inhibition of FSH action. This inhibitory effect of IL-1 beta was evident 48 h after the treatment. Furthermore, IL-1 beta inhibited forskolin (10(-5) mmol/L) and (Bu)2 cAMP (10(-2) mmol/L)-stimulated estrogen production, indicating a post-cyclic AMP site of action. The present study suggests that IL-1 beta is a potent modulator of granulosa cell steroidogenesis. Decreased estrogen formation may contribute to the follicle atresia and the impaired reproductive functions during injury and inflammation.     

A dye release assay for determination of lysostaphin activity

We describe a method for determination of lysostaphin activity using Remazol Brilliant Blue R (RBB)-dyed staphylococcal cells or RBB-dyed staphylococcal peptidoglycan as substrate. The dyed substrates are easy to prepare and are stable for at least 6 months. Soluble hydrolytic products released by lysostaphin are measured spectrophotometrically at 595 nm after the insoluble substrate is removed by filtration or centrifugation. The dye release assay is more sensitive and more accurate than the previously described turbidimetric assay.     

Deoxyribose ring conformation of [d(GGTATACC)]2: an analysis of vicinal proton-proton coupling constants from two-dimensional proton nuclear magnetic resonance

Exchangeable and nonexchangeable protons of [d(GGTATACC)]2 in aqueous cacodylate solution were assigned from two-dimensional nuclear Overhausser effect (2D NOE) spectra. With phase-sensitive COSY and double quantum filtered COSY (DQF-COSY) experiments, the cross-peaks resulting from deoxyribose ring conformation sensitive proton-proton vicinal couplings, i.e., all 1'-2', 1'-2", 2'-3', and 3'-4' couplings and six from 2"-3' couplings, were observed. From the cross-peak fine structure, the 2',2" proton assignments can be confirmed; coupling constants J1'2' and J1'2" and sums of coupling constants involving H2' and H2" for all residues and H3' for C8 were obtained. The DISCO procedure [Kessler, H., Muller, A., & Oschkinat, H. (1985) Magn. Reson. Chem. 23, 844-852] was used to extract individual 1'-2' and 1'-2" coupling constants. The sum of coupling constants involving H1' or H3' was measured from the one-dimensional spectrum where signal overlap is not a problem. Analysis of the resulting coupling constants and sums of coupling constants, in the manner of Rinkel and Altona [Rinkel, L. J., & Altona, C. (1987) J. Biomol. Struct. Dyn. 4, 621-649], led to the following conclusion: C2'-endo deoxyribose ring conformation is predominant for every residue, but a significant amount of C3'-endo conformation may exist, ranging from 14% to 30%.     

Reversible dissociation of active octamer of cyanase to inactive dimer promoted by alteration of the sulfhydryl group

Cyanase is an inducible enzyme in Escherichia coli that catalyzes the reaction of cyanate with bicarbonate resulting in the decomposition of cyanate to ammonia and bicarbonate. In this study, the role of the single sulfhydryl group in each of the eight identical subunits of cyanase was investigated. Tetranitromethane, methyl methanethiosulfonate, N-ethylmaleimide, and Hg2+ all reacted with the sulfhydryl group to give derivatives which had reduced activities and which dissociated reversibly to inactive dimer. Association of inactive dimer to active octamer was facilitated by the presence of azide (cyanate analog) and bicarbonate, increased temperature and enzyme concentration, and presence of phosphate. Nitration of tyrosine residues by tetranitromethane occurred only in the absence of azide and bicarbonate, suggesting that at least some of the tyrosine residues become exposed when octamer dissociates to dimer. Site-directed mutagenesis was used to prepare a mutant enzyme in which serine was substituted for cysteine. The mutant enzyme was catalytically active and had properties very similar to native enzyme, except that it was less stable to treatment with urea and to high temperatures. These results establish that in native cyanase the sulfhydryl group per se is not required for catalytic activity, but it may play a role in stabilizing octameric structure, and that octameric structure is required for catalytic activity.     

Comparison of activity and conformation changes during refolding of urea-denatured creatine kinase

The course of the recovery of the enzymatic activity and the native conformation during the renaturation of urea-denatured creatine kinase (ATP:creatine N-phosphotransferase, EC 2.7.3.2) has been studied. Under suitable conditions, an activity recovery of 95% can be obtained and the reactivation follows a triphasic course. The initial two phases are relatively fast, whereas the slow phase takes some 24 h to reach completion. The recovery of the native conformation has been followed by changes in fluorescence, ultraviolet absorption and in exposed SH groups and has been shown to be a biphasic process. Both the reactivation and the refolding processes are independent of protein concentrations within a certain range, showing that the dimerization of the enzyme molecule is not rate-limiting. A comparison of the rate constants for the refolding of the molecule with those for the recovery of its catalytic activity shows that these are not synchronized and the activity recovery approaches completion after the refolding and dimerization of the subunits so far as can be detected by the methods employed. The final stage of refolding with complete activity recovery probably involves subtle conformational changes of the dimeric enzyme molecule not detectable by the physiochemical methods used in the present study.     

斯氏狸殖吸虫螺类宿主新记录:洪山拟钉螺新种记述

本文报道斯氏狸殖吸虫新的螺类宿主——洪山拟钉螺Tricula hongshanensis sp. nov.的特点:螺壳较宽而短,体螺层较高大,壳口上缘成锐角,触角伸展时较长,收缩吋有环状皱褶,雄性阴茎较粗短,末端钝圆,齿舌公式不同于其它拟钉螺。