论硷性磷酸酶在组织化学上的专属性问题

一、绪言硷性磷酸酶是一种酶或是包括好几种性质相似的酶的问题,至今还没有完全被了解。1937年Bodansky用胆盐作用于肾脏和小肠的硷性磷酸酶,发现胆盐对肾脏硷性磷酸酶的抑制极强,但对小肠硷性磷酸酶的作用微弱。Emmel(1946 a,b)以小鼠的肾和小肠作为材料,在作用液中加入不同浓度的KCN(0.0001—0.01M),在37℃下作用3小时,发现小肠的硷性磷酸酶,在0.001M KCN的作用下,已完全被抑     

EVALUATION OF THE SPECIFICITY OF A LYMPHOID CHALONE

An extract from calf spleens, injected into mice, was found to inhibit their lymphocyte proliferative response to PHA-M and PWM in vitro. Despite the ability of the spleen extract to inhibit the response of lymphocytes to stimuli in vitro, no effect was observed on the repopulation of lymphocytes in the peripheral blood of sublethally irradiated mice. The data suggest that the spleen extract acts as a specific inhibitor of the immune competent cells since neither the precursors of lymphocytes nor other haematopoietic cells were affected.     

植食性昆虫的食性和营养

本文综述和讨论近年来有关植食性昆虫食性和营养的研究结果和发展。第一部分略述该类昆虫食物因理化性质的各异所引起的食性特化现象, 由此所产生的研究课题和国际对这方面的研究动态。第二部分叙述昆虫的感觉作用和食料植物选择之间的关系, 列举对不同昆虫在觅食或产卵时有诱致或驱斥效应的和在取食时有助长或抑制效应的感觉刺激的本质和昆虫反应的特点。第三部分讨论植食性昆虫的营养和代谢的特点及其与食性特化的关系, 在列举较近期间的研究成就后指出在不同种类中所存在着的营养差异, 可能和食性特化有某些联系。这类昆虫的营养需要和对植物中有毒物质的适应都是代谢类型的反映, 它们和昆虫的感觉反应有一定的联系, 在与植物建立营养的关系中同样是重要的。第四部分叙述并讨论了有关植食性昆虫食性的某些理论, 其中包括在选择食物中的机制、食性形成的主导因素、对食性类型以及食性演化的解释等。最后, 指出对有关方面研究的可能进展和成就, 及其在昆虫学各方面所起的影响。     

植食性昆虫食性的生理基础

一、引言 昆虫与植物的关系,早就被认识到是生物学中一个值得研究的课题,在理论上和应用上都有重要的意义。据统计,已描述的昆虫种类中,植食性昆虫总数在三十五万种以上(Hedin等,1974)。它们对植物的种类和取食部分都有一定的选择性,这种观象构成“食性”这一概念的主要内容(钦俊德,1962)。现有的高等植物很少能避免昆虫的取食为害;有的对昆虫的取食产生特种反应(Ryan和Green,1974),但一般均以本身变动着的营养     

SPECIFICITY OF CREATINE IN THE CONTROL OF MUSCLE PROTEIN SYNTHESIS

This study provides additional evidence that creatine, an end product of contraction unique to muscle, is involved in the control of muscle protein synthesis. Creatine is shown to stimulate selectively the rate of synthesis of two major contractile proteins, actin and myosin heavy chain, in cultures of differentiating skeletal muscle. Creatine affects only the rate of synthesis and not the rate of degradation. Several creatine analogs are as effective as creatine in stimulating muscle protein synthesis, creatinine and amino acids such as arginine and glycine are not. Creatine stimulates myosin heavy chain synthesis twofold in cultures of embryonic muscle grown in either normal or dialyzed media.     

黑曲霉突变株葡萄糖淀粉酶的底物特异性

黑曲霉(Aspergillus niger)突变株T-21葡萄糖淀粉酶(GAI)仅能水解多种淀粉及麦芽低聚糖生成唯一产物β-葡萄糖,其水解麦芽糖及麦芽三糖的速度分别为200和570mg葡萄糖·h~(-1)·mg~(-1).GAI水解α-1,4键的速度比水解α-1.6键快100多倍.除了马铃薯淀粉外,对其它淀粉及麦芽低聚糖几乎都能100%地水解,但不能水解环状糊精,其水解各麦芽低聚糖的最先产物都比原底物少一个葡萄糖单位,说明GAI为一外切型淀粉酶.GAI对麦芽糖、麦芽三糖、可溶性淀粉、糯米淀粉、糊精及糖原的Km值分别1.92mmol/L、0.38mmol/L、0.053%、0.045%、0.059%、及0.076%,V_(max)分别为590、1370、1270、1520、1120和1220mg葡萄糖·h~(-1)·mg~(-1).D-葡萄糖酸-δ-内酯及麦芽糖醇对此酶分别具有反竞争性抑制和混合性抑制.     

DIVERSITY AND HOST SPECIFICITY OF AZOLLA CYANOBIONTS1

A unique, hereditary symbiosis exists between the water fern Azolla and cyanobacteria that reside within a cavity in the dorsal leaf‐lobe of the plant. This association has been studied extensively, and questions have frequently been raised regarding the number and diversity of cyanobionts (cyanobacterial symbionts) among the different Azolla strains and species. In this work, denaturating gradient gel electrophoresis (DGGE) and a clone library based on the 16S rRNA gene were used to study the genetic diversity and host specificity of the cyanobionts in 35 Azolla strains covering a wide taxonomic and geographic range. DNA was extracted directly from the cyanobacterial packets, isolated after enzymatic digestion of the Azolla leaves. Our results indicated the existence of different cyanobiont strains among Azolla species, and diversity within a single Azolla species, independent of the geographic origin of the host. Furthermore, the cyanobiont exhibited host‐species specificity and showed most divergence between the two sections of genus Azolla, Azolla and Rhizosperma. These findings are in agreement with the recent redefinition of the taxon Azolla cristata within the section Azolla. With regard to the taxonomic status of the cyanobiont, the genus Anabaena of the Nostocaceae family was identified as the closest relative by this work.     

依赖PQQ甲醇脱氢酶对底物催化专一性差的原因分析

采用甲基营养杆菌NO .2为实验菌株 ,经超声波破细胞 ,酸处理 ,DEAE 纤维素和CM 纤维素柱层析等改进的纯化程序 ,可得到比活力为 12 .5u/mg的甲醇脱氢酶 (MDH)样品。该酶在测活系统中除能氧化甲醇等醇类化合物外 ,还能以较大速率氧化氯化铵、甲胺、脲等物质 ,MDH对不同底物亲和力的差异性主要取决于其辅基吡咯喹啉醌 (PQQ)与底物的结合力。甲醇脱氢酶与底物结合前后在特定区域的光谱有一定的差异性     

CHEMICAL SPECIFICITY OF DOPAMINE TRANSPORT IN THE NIGRO-NEOSTRIATAL PROJECTION

Axoplasmic transport of dopamine in the nigro-neostriatal system has previously been shown by the specific accumulation of labelled dopamine in the striatum following injections of labelled DOPA or dopamine into the substantia nigra. To test the specificity, 17 different labelled materials (pipecolic acid, inulin, taurine, GABA, glycine, histidine, histamine, serotonin, 5-HTP, D-amphetamine, 3-methoxytyramine, dopamine, tyramine, norepinephrine, octopamine and high and low specificity activity DOPA) were injected into the substantia nigra and the distribution of radioactivity in the brain studied after 6 and 24 h. Only the catecholamines and octopamine gave evidence of specific accumulation in the ipsilateral striatum although some of the other compounds caused diffuse labelling of the striatum along with other brain areas.     

THE EVOLUTION OF SELECTIVE AGGRESSION CONDITIONED ON ALLORECOGNITION SPECIFICITY

Many sessile cnidarians deploy specialized structures while competing aggressively for living space. The initiation of aggression is often contingent on the relatedness of the interacting contestants; clonemates and close kin generally behave passively toward one another, whereas more distant relatives generally behave aggressively. Behavioral specificity of this sort requires that there be 1) an allorecognition system that can discriminate among subtle differences in cell-surface determinants and 2) a highly polymorphic genetic system that provides specific labels of relatedness (haplotypes or allotypes). The evoutionary models analyzed in this paper show that a population of individuals that behave aggressively only against haplotypically distinct individuals (discriminating phenotypes) will not be evolutionarily stable in the face of either unconditionally aggressive or unconditionally nonaggressive phenotypes. Furthermore, even if the discriminating trait were somehow fixed, the rare recognition alleles necessary to confer allotypic specificity could not become established through natural selection. Thus, allotypic specificity is unlikely to be maintained by individual selection acting directly through aggressive behavior. Other selective mechanisms might account for the evolution of allorecognition specificity. Allotypic polymorphism could be maintained by pleiotropic mechanisms in which rare alleles are favored by natural selection acting either on gametic incompatibility, pathogen resistance, or somatic fusion, rather than aggressive behavior per se. However, these mechanisms do not explain the maintenance of selective aggression based on allotypic differences. Alternatively, if aggressive members of a clone indirectly enhance the reproductive output or survival of the entire clone (or close relatives), then kin selection acting directly through aggressive behavior could favor allorecognition specificity. Choosing among these alternatives will require the development of more sophisticated theory and empirical analyses of the costs and benefits of aggression.     

训练专一性对无氧阈测定的影响

本文对以上肢训练为主的15名优秀皮划艇运动员和以下肢训练为主的14名优秀中长跑运动员在两种常规负荷方式下的无氧阈及最大吸氧量进行了测定分析,以探讨训练专一性对无氧阈测定的影响。采用踏车式功量计和活动平板方式逐级递增负荷,通过与Apple Ⅱ_E辅助联机的Jaeger EOS自动分析系统,以通气和气体交换指标的变化,无创性地测定无氧阈和最大吸氧量。结果表明,训练专一性会影响无氧阈测定结果。欲测得最高的无氧阈值,实验室测试手段就应当尽量模拟训练时的运动形式。此外,能敏感地反映出运动训练专一性适应的是无氧阈时的吸氧量绝对值(1/min),而不是无氧阈的相对值(％Vo_2max)。