黄河三角洲芦苇种群特征对水深环境梯度的响应

通过野外调查芦苇种群特征及获取的监测数据,应用多元统计法、函数极值法以及β多样性指数测度法,对黄河三角洲芦苇种群在不同环境梯度（以水深为主）条件下的生物生态学特征及β多样性进行了分析.（1）通过离差平方和聚类分析方法,将研究区的10个调查样地划分为6个类型.随水深环境梯度变化,各样地群落优势植物也发生相应变化.（2）芦苇的平均高度和平均茎粗与平均水深呈显著相关.芦苇平均密度和平均盖度值与平均水深拟合曲线的变化呈非线性变化趋势.在平均水深为0.3m时,芦苇平均密度和平均盖度出现明显的峰,随水深变化向峰两侧递减,而芦苇平均株高和平均茎粗随水深增加呈递葺增趋势.（3）通过β多样性分析,黄河三角洲存在明显的环境梯度变化,随着水深的变化,物种间存在明显的替代关系.通过离差平方和聚类分析后得出的各相邻样地（水深段）间的Sorensen指数值均大于不相邻样地（水深段）间的值.水生环境植物群落间的相似性程度较大,而旱生环境植物群落间相似性程度较小.     

Factors in Bovine Colostrum that enhance the Migration of Human Fibroblasts in Type I Collagen Gels

Bovine colostrum has an activity that increases the migration of WI38 fibroblasts. We evaluated the motility of fibroblasts by their ability to contract collagen gels. Part of the activity was absorbed by anion-exchange chromatography at pH 6.4, and eluted by 0.2-0.3 M sodium chloride. The activity was separated into many fractions corresponding to 20-150 kDa by gel filtration chromatography under acidic conditions. The major peak of the activity coincided with 50-70 kDa.     

Genetics of esterases in species of Lycopersicon

Summary Improvements in plant culture and electrophoretic technique permit detection and genetic analysis of seven esterase loci in Lycopersicon esculentum and related species with homosequential chromosomes. At all of these loci except one, each allele codes for a single anodal band, and the electrophoretic variants are inherited in monogenic fashion. For the exceptional Est-4, allozymes are 1–3 banded in various combinations at four positions, and rare recombinants in one cross appeared at a frequency of 0.0005, suggesting the existence of several very tightly linked genes. Est-2 segregated solely for intensity differences in dominant/recessive fashion; Est-3 and Est-4 behave as monomers; the remaining Est-l, 5, 6, and 7 — coding for contiguous bands in the region closest to the origin — are dimeric. The latter group are tightly linked inter se in the proximal portion of 2L (long arm of chromosome 2), the total map distance of the complex being approximately 1.5 cM; Est-2 is situated on 9L between ah and marm; Est-3 on 1L between inv and dgt; Est-4 has not yet been located. Even in the interspecific hybrids, map distances are similar to the standard values for L. esculentum. Tandem duplication is hypothesized for the origin of the Est-l, 5–7 complex, which adds another example to the growing list of linked mimic genes in the tomato genome. In respect to the position of their bands and tight inter se linkage, this series exactly parallels the EA, EB, EC esterase series in Hordeum vulgare — a fact which suggests great antiquity for this block of genes.     

New convenient defined media for [(35)S]methionine labelling and proteomic analyses of probiotic lactobacilli

AIMS: To develop experimental conditions for efficient protein radiolabelling and two-dimensional (2D) polyacrylamide gel electrophoresis for investigation of stress proteomes of probiotic Lactobacillus spp. METHODS AND RESULTS: Three chemically defined media (CDM) optimized from a commercial medium supported rapid growth of the probiotic Lactobacillus rhamnosus E97800, Lactobacillus brevis ATCC 8287 and Lactobacillus reuteri E97849, and a broad range of other lactic acid bacteria. These CDM allowed efficient protein radiolabelling, requiring as little as 200 mul of logarithmic culture and pulse-chase labelling of 20 min to detect c. 300 distinct protein spots in a mini-scale 2D-gel. Proteins including DnaK, GroEL and ClpATPases were identified from the 2D-gels by immunoblotting. CONCLUSIONS: Radiolabelling coupled with 2D gel electrophoresis provides a sensitive means to monitor changes in protein synthesis rates in probistic lactobacilli. SIGNIFICANCE AND IMPACT OF THE STUDY: Efficient tools for proteomic analyses of probiotic Lactobacillus were developed and applied for stress-response studies.