生物种群动态微分方程模型参数估计方法

本文以数值分析和最优化技术的有机结合为基础,提出了一种新的对动态微分方程模型直接进行数据拟合和参数估计方法,并以Logistic微分方程、生物种间竞争关系微分方程以及一种复合形态的Logistic微分方程为例进行了数据拟合试验．结果表明,该方法对各种动态微分方程模型均能进行最优拟合分析并求解其参数．同时发现,以前有的作者〔1,2,3,4,5〕提出的方法所得到的参数估计值存在系统误差且误差较大．     

油麻藤凝集素的荧光光谱研究

用化学修饰、内源荧光和荧光淬灭等方法研究了油麻藤凝集素（ＭＳＬ）的溶液构象变化和微环境的构象特征。研究发现ＭＳＬ分子中总共有９个色氨酸（Ｔｒｐ）残基,它们的荧光能被丙烯酰胺淬灭,但不易为ＫＩ接近而淬灭,ＭＳＬ经Ｎ－溴代琥珀酰亚胺（ＮＢＳ）修饰后,其内源性荧光发射谱发生相应变化,结果表明ＭＳＬ分子中部分Ｔｒｐ残基埋藏于分子内部,而位于分子表面的Ｔｒｐ残基可能处于分子的疏水袋中。     

黄精凝集素Ⅱ分子稳定性与生物学活性研究

黄精凝集素Ⅱ分子稳定性与生物学活性研究鲍锦库,曾仲奎,周红（四川大学生物系,成都,６１００６４）本文在黄精凝集素Ⅱ纯化及性质研究的基础上,应用多种变性条件,研究其分子特性,同时对分子的巯基和色氨酸进行修饰,研究该凝集素分子保持其生物学活性与这些基团的...     

A NEW SPECIES OF GENUS HABROPHLEBIODES ULMER (EPHEMEROPTERA: LEPTOPHLEBIIDAE)

Abstract  The present paper deals with a new species Habrophlebiodes zijinensis sp. nov. collected in Nanjing, Jiangsu Povince, China.     

Promoters from kin1 and cor6.6, two Arabidopsis thaliana low-temperature-and ABA-inducible genes,direct strong β-glucuronidase expression in guard cells,pollen and young developing seeds

The ability of most higher plants to withstand freezing can be enhanced by cold acclimation, although the freezing tolerance of plant tissues is also affected by their developmental stage. In addition, low temperature has pleiotropic effects on many plant developmental processes such as vernalization. The interaction between plant development and low temperature implies that some genes are regulated by both environmental factors and developmental cues. Although a number of cold-inducible genes from plants have been identified, information concerning their regulation during plant development is limited. In order to understand their developmental regulation and obtain possible clues as to function, the promoters of kin1 and cor6.6, two cold- and abscisic acid (ABA)-regulated genes from Arabidopsis thaliana, were fused to the -glucuronidase (GUS)-coding sequence and the resulting constructs were used to transform tobacco and A. thaliana. Transgenic plants with either the kin1 or cor6.6 promoter showed strong GUS expression in pollen, developing seeds, trichomes and, most interestingly, in guard cells. During pollen development, maximum GUS activity was found in mature pollen. In contrast, the maximum GUS activity during seed development was during early embryogenesis. These patterns of expression distinguish kin1 and cor6.6 from related lea genes which are strongly expressed during late embryogenesis. There was no major qualitative difference in patterns of GUS expression between kin1 and cor6.6 promoters and the results were similar for transgenic tobacco and Arabidopsis. Considering the results described, as well as those in an accompanying paper Wang et al., 1995, Plant Mol Biol 28: 605–617 (this issue), we suggest that osmotic potential might be a major factor in regulating the expression of kin1 and cor6.6 during several developmental processes. The implication of the results for possible function of the gene products is discussed.     

Mutational analysis of Saccharomyces cerevisiae U4 small nuclear RNA identifies functionally important domains.

U4 small nuclear RNA (snRNA) is essential for pre-mRNA splicing, although its role is not yet clear. On the basis of a model structure (C. Guthrie and B. Patterson, Annu. Rev. Genet. 22:387-419, 1988), the molecule can be thought of as having six domains: stem II, 5' stem-loop, stem I, central region, 3' stem-loop, and 3'-terminal region. We have carried out extensive mutagenesis of the yeast U4 snRNA gene (SNR14) and have obtained information on the effect of mutations at 105 of its 160 nucleotides. Fifteen critical residues in the U4 snRNA have been identified in four domains: stem II, the 5' stem-loop, stem I, and the 3'-terminal region. These domains have been shown previously to be insensitive to oligonucleotide-directed RNase H cleavage (Y. Xu, S. Petersen-Bjørn, and J. D. Friesen, Mol. Cell. Biol. 10:1217-1225, 1990), suggesting that they are involved in intra- or intermolecular interactions. Stem II, a region that base pairs with U6 snRNA, is the most sensitive to mutation of all U4 snRNA domains. In contrast, stem I is surprisingly insensitive to mutational change, which brings into question its role in base pairing with U6 snRNA. All mutations in the putative Sm site of U4 snRNA yield a lethal or conditional-lethal phenotype, indicating that this region is important functionally. Only two nucleotides in the 5' stem-loop are sensitive to mutation; most of this domain can tolerate point mutations or small deletions. The 3' stem-loop, while essential, is very tolerant of change. A large portion of the central domain can be removed or expanded with only minor effects on phenotype, suggesting that it has little function of its own. Analysis of conditional mutations in stem II and stem I indicates that although these single-base changes do not have a dramatic effect on U4 snRNA stability, they are defective in RNA splicing in vivo and in vitro, as well as in spliceosome assembly. These results are discussed in the context of current knowledge of the interactions involving U4 snRNA.