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101.
本文通过研究提出了一种由大肠杆菌细胞中提取重组猪生长激素的方法。提取回收率为52.4%,纯度为94.1%,具有生物学活性。 相似文献
102.
The Hyper-Gene Conversion Hpr5-1 Mutation of Saccharomyces Cerevisiae Is an Allele of the Srs2/Radh Gene 总被引:7,自引:2,他引:5
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The HPR5 gene has been defined by the mutation hpr5-1 that results in an increased rate of gene conversion. This mutation suppresses the UV sensitive phenotype of rad18 mutations in hpr5-1 rad18 double mutants by channeling the aborted repair events into a recombination repair pathway. The HPR5 gene has been cloned and is shown to be allelic to the SRS2/RADH gene, a putative DNA helicase. The HPR5 gene, which is nonessential, is tightly linked to the ARG3 locus chromosome X. The hpr5-1 allele contains missense mutation in the putative ATP binding domain. A comparison of the recombination properties of the hpr5-1 allele and the null allele suggests that recombination events in hpr5 defective strains can be generated by several mechanisms. We propose that the HPR5 gene functions in the RAD6 repair pathway. 相似文献
103.
草鱼血液学的研究:Ⅱ.血清电解质和尿素氮的周年变化 总被引:1,自引:0,他引:1
本文研究了草鱼稚鱼血清钾、钠、钙、氯、无机磷和尿素氮含量的周年变动规律,分析了水温、体重对上述血液化学成分的影响。结果显示其周年变动无一定规律性可循。血清钠、氯变动辐度较小,无机磷和尿素氮变动幅度较大,幅值约有4倍。水温与血清钾显示正相关(P≤0.05),与钠、钙显示负相关(P≤0.01,P≤0.05)。血清钠、尿素氮有随体重增加含量增高的趋势,而钾却显著减少。 相似文献
104.
抑菌生的研究总结报告 总被引:6,自引:1,他引:5
本文报告一种由枯草杆菌制成的生态制剂,并命名为抑菌生(Subtilobiogen)。该制剂对创、烧伤感染有治疗作用。经过安全试验、急性毒性试验、Ames试验和微核试验证明,该制剂是一种无害、无毒和有致突变作用的活菌制剂。抑菌生有膏剂、乳剂及粉剂3种剂型。抑菌生在试管和体内对金黄色葡萄球菌、绿脓杆菌和大肠杆菌均具有抑菌作用。临床观察证明,将抑菌生喷洒在创面上,对浅Ⅱ°度、深Ⅱ°度及混合型烧伤感染均具有明显疗效。实验组(181例)与对照组(174例)相比较,在统计学上具有显著性差异。抑菌生的作用机制,经过初步试验证明,与营养争夺和占位性保护有关,因为枯草杆菌的生长速度超过金黄色葡萄球菌、绿脓杆菌和大肠杆菌的生长速度。 相似文献
105.
Three B. subitilis serine tRNAs were sequenced including modified nucleosides. All the serine tRNAs contained 1-methyl-adenosine in the D-loop. As other characteristic modified nucleosides, 5-methoxyuridine was found in the first letter of the anticodon in the tRNA(UGA). 相似文献
106.
Huiling Hao Yunquan Jiang S. J. Zhang Peng Zhang Rong X. Zeng Marietta Y. W. T. Lee 《Chromosoma》1992,102(Z1):S121-S127
A continuing theme of our laboraory, has been the understanding of human DNA polymerases at the structural level. We have
purified DNA polymerases delta, epsilon and alpha from human placenta. Monoclonal antibodies to these polymerases were isolated
and used as tools to study their immunochemical relationships. These studies have shown that while DNA polymerases delta,
epsilon and alpha are discrete protiens, they must share common structural features by virtue of the ability of several of
our monoclonal antibodies to exhibit cross-reactivity. A second approach we have taken is the molecular cloning of human DNA
polymerase delta and epsilon. We have cloned the DNA polymerase delta cDNA, and this has allowed us to compare its primary
structure to those of human polymerase alpha and other members of this polymerase family. Multiple sequence alignments have
revealed that human DNA polymerase delta is also closely related to the herpes virus family of DNA polymerases. In situ hybridization
has shown that the human DNA polymerase delta gene is localized to chromosome 19 q13.3–q13.4. In order to further determine
the functional regions of the DNA polymerase δ structure we are currently expressing human pol δ inE. coli and baculovirus systems. Other work in our laboratory is directed toward examining the expression of DNA polymerase δ during
the cell cycle. 相似文献
107.
Steroidal saponins from Smilax lebrunii. 总被引:5,自引:0,他引:5
Two new steroidal saponins, (25 R)-spirostan-3 beta-ol-6-one-3-O-[alpha-L-arabinopyranosyl (1----6)]-beta-D-glucopyranoside and (25 R)-spirostan-3 beta-ol-6-one-3-O-[beta-D-glucopyranosyl(1---4)] [alpha-L-arabinopyranosyl(1----6)]-beta-glucopyranoside, were isolated from the rhizomes of Smilax lebrunii. Their structures have been established by chemical and spectral methods. 相似文献
108.
Two new compounds, pedicularioside E and F, were isolated from whole plants of Pedicularis lasiophrys, along with the four known compounds, verbascoside, cistanoside C, cistanoside D and 8-epiloganin. On the basis of spectral and chemical evidence, pedicularioside E and F were identified to be 1'-O-beta-D-(3-methoxy-4-hydroxy-beta-phenyl)-ethyl-6'-O-feruloyl- alpha-L-(2-acetyl)-rhamnosyl-(1----3')-4'-acetylglucopyranoside and shanzhisin methyl ester cellobioside, respectively. 相似文献
109.
Genomic in situ hybridization to identify alien chromosomes and chromosome segments in wheat 总被引:15,自引:0,他引:15
T. Schwarzacher K. Anamthawat-Jónsson G. E. Harrison A. K. M. R. Islam J. Z. Jia I. P. King A. R. Leitch T. E. Miller S. M. Reader W. J. Rogers M. Shi J. S. Heslop-Harrison 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1992,84(7-8):778-786
Summary Genomic in situ hybridization was used to identify alien chromatin in chromosome spreads of wheat, Triticum aestivum L., lines incorporating chromosomes from Leymus multicaulis (Kar. and Kir.) Tzvelev and Thinopyrum bessarabicum (Savul. and Rayss) Löve, and chromosome arms from Hordeum chilense Roem. and Schult, H. vulgare L. and Secale cereale L. Total genomic DNA from the introgressed alien species was used as a probe, together with excess amounts of unlabelled blocking DNA from wheat, for DNA:DNA in-situ hybridization. The method labelled the alien chromatin yellow-green, while the wheat chromosomes showed only the orange-red fluorescence of the DNA counterstain. Nuclei were screened from seedling root-tips (including those from half-grains) and anther wall tissue. The genomic probing method identified alien chromosomes and chromosome arms and allowed counting in nuclei at all stages of the cell cycle, so complete metaphases were not needed. At prophase or interphase, two labelled domains were visible in most nuclei from disomic lines, while only one labelled domain was visible in monosomic lines. At metaphase, direct visualization of the morphology of the alien chromosome or chromosome segment was possible and allowed identification of the relationship of the alien chromatin to the wheat chromosomes. The genomic in-situ hybridization method is fast, sensitive, accurate and informative. Hence it is likely to be of great value for both cytogenetic analysis and in plant breeding programmes. 相似文献
110.
A difference equation model for the dynamics of a semelparous size-structured species consisting of juvenile and adult individuals
is derived and studied. The adult population consists of two size classes, a smaller class and a larger more fertile class.
Negative feedback occurs through slowed juvenile growth due to increased total population levels during the developmental
period and consequently a smaller adult size at maturation. Intra-specific competition coefficients are size dependent and
measure the strength of intra-specific competition between juveniles and adults. It is shown that equilibrium states in which
adults and juveniles occur together at all times are in general destabilized by significantly increased juvenilevs adults competition with the result that stable periodic cycles appear, in which the generations alternate in time and hence
avoid competition. This result supports the tenet that intra-specific competition between juveniles and adults is destabilizing.
Exceptions to this destabilization principle are found, however, in which populations exhibiting non-equilibrium, aperiodic
dynamics can be equilibrated by increase competition between juveniles and adults. This occurs, for example, when adult fertility
and competition coefficients are significantly size class dependent.
The author gratefully acknowledges the support of the Applied Mathematics Division and the Population Biology/Ecology Division
of the National Science Foundation under NSF grant No. DMS-8902508.
Research supported by the Department of Energy under contracts W-7405-ENG-36 and KC-07-01-01. 相似文献