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31.
32.
Nucleotide sequence and expression of cheF, an essential gene for chemotaxis in Bacillus subtilis. 总被引:4,自引:4,他引:0
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The cheF gene, which is involved in chemotaxis in Bacillus subtilis, has been cloned, expressed, and sequenced. This gene is contained in a 0.7-kilobase PstI DNA fragment that was isolated from a lambda Charon 4A B. subtilis chromosomal DNA library. This fragment was subcloned into the expression vector pSI-1 and shown to complement the cheF mutation both for chemotaxis and for methanol production in response to the addition of attractants. Plasmid-encoded DNA expression in B. subtilis maxicells indicated that a membrane-associated polypeptide of 20-kilodaltons was expressed from this 0.7-kilobase DNA. The nucleotide sequence of this DNA fragment was determined, and an open reading frame capable of encoding a putative 175-amino-acid protein (Mr 20,002) was identified. In an effort to understand the function of the cheF protein, the dosage of the cheF gene product was varied by altering the concentration of IPTG (isopropyl-beta-D-thiogalactopyranoside) during growth. In the presence of high concentrations of IPTG, chemotaxis was inhibited and methanol production was impaired. 相似文献
33.
本文研究了不同底物(N_2,H_2,N_2O,NaN_3,C_2H_2)对棕色固氮菌固氮酶及其钼铁蛋白荧光光谱的影响。结果表明,上述底物均能络合在钼铁蛋白及固氮酶上,但络合程度不同,从而为固氮酶系统有多个不同的底物络合中心,底物络合中心在钼铁蛋白分子上,铁蛋白对钼铁蛋白有变构作用,提供了光谱学证据。 相似文献
34.
槐种子发育中胚乳细胞半乳甘露聚糖积累的研究 总被引:2,自引:0,他引:2
槐 ( Sophora japonica L.)开花约 60 d至种子成熟 ,为胚乳半乳甘露聚糖积累期。用组织化学方法 ,对储藏于胚乳细胞壁上的半乳甘露聚糖的形成积累进行了观察 ,结果表明 ,半乳甘露聚糖最先在邻近胚的胚乳细胞的粗面内质网的囊泡腔内形成 ,并通过细胞质膜分泌至细胞壁周围。此后 ,半乳甘露聚糖的积累逐渐向种皮方向扩展 ,及至种子成熟时 ,除糊粉层外 ,所有胚乳细胞几乎全由多糖所填充。此外 ,对半乳甘露聚糖发生部位及其积累过程的消长变化进行了讨论 相似文献
35.
A. Petronis A. S. Bassett W. G. Honer J. B. Vincent Y. Tatuch T. Sasaki D. J. Ying T. A. Klempan J. L. Kennedy 《American journal of human genetics》1996,59(4):905-911
Evidence for genetic anticipation has recently become an important subject of research in clinical psychiatric genetics. Renewed interest in anticipation was evoked by molecular genetic findings of a novel type of mutation termed "unstable DNA." The unstable DNA model can be construed as the "best fit" for schizophrenia twin and family epidemiological data. We have performed a large-scale Southern blot hybridization, asymmetrical PCR-based, and repeat expansion-detection screening for (CAG)n/(CTG)n and (CCG)n/(CGG)n expansions in eastern Canadian schizophrenia multiplex families demonstrating genetic anticipation. There were no differences in (CAG)n/(CTG)n and (CCG)n/(CGG)n pattern distribution either between affected and unaffected individuals or across generations. Our findings do not support the hypothesis that large (CAG)n/(CTG)n or (CCG)n/(CGG)n expansions are the major etiologic factor in schizophrenia. A separate set of experiments directed to the analysis of small (30-130 trinucleotides), Huntington disease-type expansions in individual genes is required in order to fully exclude the presence of (CAG)n/(CTG)n- or (CCG)n/(CGG)n-type unstable mutation. 相似文献
36.
Kjetil Taskn Rigmor Solberg Ying Zhao Vidar Hansson Tore Jahnsen Michael J. Siciliano 《Genomics》1996,36(3):535
We have determined the chromosomal localization of the gene for the catalytic subunit Cα of cAMP-dependent protein kinase (locus PRKACA) to human chromosome 19 using polymerase chain reaction (PCR) and Southern blot analysis of two different somatic cell hybrid mapping panels. In addition, PCR analysis of a chromosome 19 mapping panel revealed the presence of a human Cα-specific amplification product only in cell lines containing the region 19p13.1 to 19q12. Finally, two-color fluorescencein situhybridization to metaphase chromosomes using the human Cα cDNA and human chromosome 19 inter-Alu-PCR product as probes localized the human Cα gene to chromosome region 19p13.1. 相似文献
37.
In the present study we have characterized the synthesis of members of the HSP30 family during Xenopus laevis development using a polyclonal antipeptide antibody derived from the carboxyl end of HSP30C. Two-dimensional PAGE/immunoblot analysis was unable to detect any heat-inducible small HSPs in cleavage, blastula, gastrula, or neurula stage embryos. However, heat-inducible accumulation of a single protein was first detectable in early tailbud embryos with an additional 5 HSPs at the late tailbud stage and a total of 13 small HSPs at the early tadpole stage. In the Xenopus A6 kidney epithelial cell line, a total of eight heat-inducible small HSPs were detected by this antibody. Comparison of the pattern of protein synthesis in embryos and somatic cells revealed a number of common and unique heat inducible proteins in Xenopus embryos and cultured kidney epithelial cells. To specifically identify the protein product of the HSP30C gene, we made a chimeric gene construct with the Xenopus HSP30C coding sequence under the control of a constitutive promoter. This construct was microinjected into fertilized eggs and resulted in the premature and constitutive synthesis of the HSP30C protein in gastrula stage embryos. Through a series of mixing experiments, we were able to specifically identify the protein encoded by the HSP30C gene in embryos and somatic cells and to conclude that HSP30C synthesis was first heat-inducible at the early tailbud stage of development. The differential pattern of heat-inducible accumulation of members of the HSP30 family during Xenopus development suggests that these proteins may have distinct functions at specific embryonic stages during a stress response. 相似文献
38.
以7690-Xu荧光染色法结合WuT3、WuT4、WuT8致敏红细胞花环实验观察经胸腺细胞分层液分离所得高密度亚群和低密度亚群人胎胸腺细胞的异质性荧光及其膜分化抗原CD3、CD4、CD8的表达。结果表明:不同胎龄胎儿胸腺细胞悬液呈现相似形态和相似分布特征的8种异质性荧光的细胞,其中,墨黑核细胞和桔红核细胞分布于两密度亚群,表型为CD3-CD4-CD8-;少数深蓝核和蓝核细胞分布于低密度亚群.表型为CD3+,属成熟的胸腺细胞;大多数深蓝核和蓝核细胞、灰蓝核细胞、灰黄核细胞及部分淡桔黄核细胞分布于高密度亚群,表型为CD3-、CD4+、CD8+,为处于中间发育阶段的胸腺细胞。推测这些细胞胞核由深蓝、蓝、灰蓝、灰黄到淡桔黄的荧光光谱的偏移可能与中间发育阶段所发生的生物及理化变化有关。 相似文献
39.
鳗鱼肌肉的氨基酸及营养价值 总被引:7,自引:1,他引:6
孔晓荣 《氨基酸和生物资源》1995,17(2):33-35
通过对优质食用鱼类—鳗鱼肌肉的氨基酸进行测定证实,鳗鱼较之其它鱼类是一种营养价值更高、滋味更鲜美的鱼类。并且,根据结果氨基酸组成比例,可为鳗鱼的人工饲养等方面的研究提供理论依据。 相似文献
40.
用中性红标记酵母原生质体初探 总被引:1,自引:0,他引:1
用2%蜗牛酶处理酵母细胞60分钟,啤酒酵母Y29的原生质体形成率为90%,再生率为9.5%;糖化酵母IB的原生质体形成率为86%,再生率为12%。用500ppm中性红染液对Y29菌株的整细胞和原生质体染色15分钟,细胞的着色率为84%,存活率为12%,而原生质体的着色率为75%,再生率为6.4%,经染色后的原生质体体积缩小,在交变电场中排队所需的场强电降低。 相似文献