乳链菌肽的分离纯化和部分生物学性质

用乳酸链球菌ＳＭ５２６进行乳链菌肽的发酵生产,产量为４０～５０ｍｇ／ｌ．经中空纤维超滤器超滤,非极性大孔吸附树脂ＸＡＤ－２层析,ＣＭ－ＳｅｐｈａｄｅｘＣ－２５层析和ＳｅｐｈａｄｅｘＧ－５０层析纯化了该肽。ＳＤＳ－ＰＡＧＥ表明达均一,ＲＰ－ＨＰＬＣ表明其纯度不低于９５％。ＳＤＳ－ＰＡＧＥ测其Ｍｒ约为３６００,用ＩＥＦ测其等电点为９．５．酸性条件下稳定且抗热;对胰蛋白酶、胃蛋白酶和木瓜蛋白酶不敏感,但对α－胰凝乳酶和蛋白酶Ｋ敏感。乳链菌肽对多种革兰氏阳性菌有强烈的抑制作用;以枯草杆菌和金黄色葡萄球菌为指示菌,其作用方式是杀菌。     

Multiplicity of brain cysteine sulfinic acid decarboxylase — Purification,characterization and subunit structure

Cysteine sulfinic acid decarboxylase (CSAD), the rate-limiting enzyme in taurine biosynthesis, appears to be present in the brain in multiple isoforms. Two distinct forms of CSAD, referred to as CSAD I and CSAD II, were obtained on Sephadex G-100 column. CSAD I and CSAD II differ in (1) the elution profile on Sephadex G-100 column; (2) the sensitivity towards Mn²⁺, methione, and other sulfur-containing amino acids and (3) their immunologic properties. CSAD II has been purified to about 2,500-fold by a combination of column chromatographies and polyacrylamide gel electrophoresis (PAGE). The purity of the enzyme preparation was established as judged from the following observations: (1) a single protein band was observed under various electrophoretic conditions, e.g., 5–20% nondenaturing PAGE, 7% nondenaturing PAGE and 10% SDS-PAGE and (2) in nondenaturing PAGE, the protein band comigrated with CSAD activity. CSAD II has a molecular weight of 90 kDa and is a homodimer consisting of two 43 ± 2 kDa subunits. CSAD appears to require Mn²⁺ for its maximum activity. Other divalent cations fail to replace Mn²⁺ in activation of CSAD activity. However, the precise role of Mn²⁺ in the action of CSAD remains to be determined.     

Inheritance of gusA and neo genes in transgenic rice

Inheritance of foreign genes neo and gusA in rice (Oryza sativa L. cv. IR54 and Radon) has been investigated in three different primary (T₀) transformants and their progeny plants. T₀ plants were obtained by co-transforming protoplasts from two different rice suspension cultures with the neomycin phosphotransferase II gene [neo or aph (3) II] and the -glucuronidase gene (uidA or gusA) residing on separate chimeric plasmid constructs. The suspension cultures were derived from callus of immature embryos of indica variety IR54 and japonica variety Radon. One transgenic line of Radon (AR2) contained neo driven by the CaMV 35S promoter and gusA driven by the rice actin promoter. A second Radon line (R3) contained neo driven by the CaMV 35S promoter and gusA driven by a promoter of the rice tungro bacilliform virus. The third transgenic line, IR54-1, contained neo driven by the CaMV 35S promoter and gusA driven by the CaMV 35S.Inheritance of the transgenes in progeny of the transgenic rice was investigated by Southern blot analysis and enzyme assays. Southern blot analysis of genomic DNA showed that, regardless of copy numbers of the transgenes in the plant genome and the fact that the two transgenes resided on two different plasmids before transformation, the introduced gusA and neo genes were stably transmitted from one generation to another and co-inherited together in transgenic rice progeny plants derived from self-pollination. Analysis of GUS and NPT II activities in T₁ to T₂ plants provided evidence that inheritance of the gusA and neo genes was in a Mendelian fashion in one plant line (AR2), and in an irregular fashion in the two other plant lines (R3 and IR54-1). Homozygous progeny plants expressing the gusA and neo genes were obtained in the T₂ generation of AR2, but the homozygous state was not found in the other two lines of transgenic rice.     

Vero细胞毒素大肠菌（VTEC）的分离及表型和分子生物学特性的研究

２６株Ｖｅｒｏ细胞毒素（ＶＴ）阳性大肠菌,经分子生物学鉴定表明,其中１４株与ＥＨＥＣ探针杂交阳性,按Ｌｅｖｉｎｅ等的标准判定属产Ｖｅｒｏ细胞毒素大肠菌（ＶＴＥＣ）,其血清型为Ｏ_１５７：Ｈ_７３株（血便２株,脓血便１株）,Ｏ_２５７ＮＭ３株（血便１株,腹泻牛便２株）,Ｏ_２９样便１株）;其余１２株虽ＶＴ毒素阳性,但ＥＨＥＣ探针阴性,按标准判定尚难确认,有待进一步研究。     

云南普通马矮型马蛋白多态性及其品种分化关系

本文运用蛋白电泳技术对来自云南省文山州马关县和麻栗坡县的２１匹普通马和１４匹矮型马进行了分析。共分析遗传座位４４个,其中有１０个座位检测到多态性。根据分子钟假说和相应的公式,推算两者的分歧时间约为１８．５万年。     

发情期小灵猫行为的研究

本文对笼养小灵猫发情期的繁殖行为进行了观察。结果表明：小灵猫一年有两次发情期,绝大部分的小灵猫在春季（２－４月）发情,少数个体在秋季（８月底至９月）出现第２次发情。发情期雄性小灵猫频繁地发出求偶叫声和增加擦香次数。雄猫的擦香行为和求偶叫声可促使雌猫的发情,发情期一系列性行为对雌雄交配的成功与否有重要的意义。     

Effects of light-dark cycles on the circadian conidiation rhythm inNeurospora crassa

The effects of 24 hr light-dark cycles on the circadian conidiation rhythm inNeurospora crassa were compared among will-typefrq ⁺ and clock mutantsfrq ⁺,frq ³,frq ⁷,frq ⁹ andfrq ¹¹. The minimum length of the light period necessary for complete entrainment to the light-dark cycles was almost 2 hr infrq ⁺,frq ³ andfrq ⁷ strains. The minimum duration of the dark period necessary for the appearance of circadian conidiation was almost 4 hr in all of the strains except thefrq ¹¹ strain. The phase of the conidiation rhythm was dependent on the light to dark transition in thefrq ¹ strain in all light-dark cycles examined and in thefrq ⁺ andfrq ³ strains when the light period was shorter than 16 hr. In contrast, the phase of thefrq ⁷ strain was dependent on the light to dark transition when the light period was shorter than 10 hr.     

银额果蝇自然群体分化过程中的细胞遗传学

对我国大陆银额果蝇的分布及其细胞遗传学进行了广泛的调查,发现了一种值得注意的新核型。该核型结构兼有早已认可的长、短两大类基本核型的特征,即核型中的两条同源４号染色体为１长１短型。含新核型的群体分布于我国大陆东南沿海一带的上海、福州、厦门和深圳。而且,这些自然群体内还出现“１长１短型”、“长型”和“短型”重叠并存的多态现象。跟踪研究表明,新核型具有不稳定的遗传性,能世代传递,它的频率随世代增长而降低,并不是突然消失。但是,在上海、福州群体内出现的“长型”至第十五代之后却全部消失。这种新核型大概是银额果蝇自然演化过程中的中间过渡核型,是该果蝇种群分化中的细胞遗传学变异的过渡表征