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When stimulated with serum, quiescent Balb/C-3T3 fibroblasts were found to induce vinculin transcription transiently within 30 min, followed by accumulation of vinculin mRNA and protein synthesis between 2 and 4 h after stimulation and a decrease to the basal level by 6-8 h. Platelet-derived growth factor (PDGF), fibroblast growth factor (FGF), and 12-O-tetradecanoylphorbol-13-acetate (TPA) each could elicit a similar response, albeit to a lesser extent, whereas epidermal growth factor (EGF) was inefficient in inducing vinculin expression. In cells stimulated with serum and cycloheximide, vinculin expression was superinduced and vinculin mRNA levels persisted longer than in cells stimulated with serum alone. Cells arrested in the presence of serum by anchorage denial in methyl cellulose suspension culture also induced vinculin expression and formed large vinculin positive plaques when reattaching and spreading on the substrate in the presence of serum. Cells replated from suspension culture in the absence of serum on either plastic or extracellular matrix (ECM) components were capable of extensive spreading, but failed to elevate vinculin expression and displayed diffuse vinculin staining. The results indicate that the changes in vinculin organization and expression in response to growth factor stimulation may reflect either a necessary step in the progression through the cell cycle or a response related to complex cellular processes such as wound repair and embryogenesis.

Aim This study examines the hypothesis that the biogeographic history of a species is reflected in the distribution of molecular genetic diversity and the phylogenies of extant populations.Location Populations of arctic-alpine ground beetle Amara alpina were analysed from Beringia (Alaska and northernmost British Columbia), the Hudson Bay region, the northern Appalachian Mountains, and the central Rocky Mountains of North America.Methods Mitochondrial restriction site variation of specimens from twenty-two populations were assayed by using radioactively labelled mtDNA to probe Southern membranes containing restriction enzyme digested total DNA. Restriction sites were mapped and genetic distances were calculated by pairwise comparison of presence and absence of restriction sites. Genetic distances were used in a molecular analysis of variance and to construct a minimal spanning tree. Parsimony methods were used to investigate the phylogenetic relationships between the haplotypes. These results were compared to an existing model for postglacial dispersal based on fossil and modern occurrences of arcticalpine beetles. ResultsAmong the twenty-two populations, fifteen haplotypes were detected. Genetic variation within each of the four regions corresponded to that expected from the palaeontologically based model. Beringian populations were the most genetically diverse. In contrast, no restriction site variation was observed in populations from the Hudson Bay region. Intermediate amounts of variation were observed in alpine populations of the Rocky and Appalachian Mountains. Maximum parsimony and cluster analysis provide evidence that at least two ancestral haplotypes existed in the Southern refugium from which the Rocky and the Appalachian Mountains populations were founded. Main conclusionsThe genetic results are generally consistent with the palaeontologically based model. The diversity of Beringian populations is consistent with this region having been continuously inhabited by Amara alpina throughout the Pleistocene. The Hudson Bay region was not deglaciated until about 6000 years, and its populations have no restriction site variation. The molecular genetic data support the interpretation that the Hudson Bay region was colonized from Beringia based on the occurrence of the same haplotype in both regions.

A cDNA (D7-8B) 1456 nucleotides in length was isolated from an adult, female-specific Anopheles gambiae library and identified as a member of the glutathione S-transferase (GST) gene family by virtue of the inferred amino acid sequence. The gene, AgGST2-1, specifies a protein that is 57% identical to the Drosophila melanogaster gene, DmGST-2. The conceptual translation product also shows similarity to the pi family of vertebrate GSTs. Northern analysis reveals multiple and abundant transcription products in larval, pupal and adult RNA preparations. Southern analyses of genomic DNA and hybridizations in situ to polytene chromosomes both suggest that there are multiple members of the GST gene family in Anopheles gambiae.