Focal adhesion kinase and Src mediate integrin regulation of insulin receptor phosphorylation.

We show here that phosphorylation of the insulin receptor and insulin receptor substrate-1 is increased when suspended cells are replated on fibronectin. This is not due to decreased numbers of cell surface receptors, alteration of insulin binding, or stimulation of a phosphatase activity in non-adherent cells. Expression of Src together with focal adhesion kinase (FAK) in suspended cells restores insulin-induced receptor autophosphorylation to levels observed in fibronectin-attached cells. Conversely, expression of dominant-negative mutants of either Src or FAK abolishes potentiation of insulin receptor phosphorylation by cell adhesion. The results suggest that both Src and FAK participate in integrin-mediated regulation of insulin receptor signal.     

Pattern development of the vegetation during colonization of a burnt heathland in Brittany (France)

Plant Ecology - The main part of the heathlands in the Paimpont area (Morbihan, and Ille-et-Vilaine, France) was burnt during spring and summer 1976. The pattern development of the vegetation was...     

Identification of large selective sweeps associated with major genes in cattle

Selection for new favorable variants can lead to selective sweeps. However, such sweeps might be rare in the evolution of different species for which polygenic adaptation or selection on standing variation might be more common. Still, strong selective sweeps have been described in domestic species such as chicken lines or dog breeds. The goal of our study was to use a panel of individuals from 12 different cattle breeds genotyped at high density (800K SNPs) to perform a whole‐genome scan for selective sweeps defined as unexpectedly long stretches of reduced heterozygosity. To that end, we developed a hidden Markov model in which one of the hidden states corresponds to regions of reduced heterozygosity. Some unexpectedly long regions were identified. Among those, six contained genes known to affect traits with simple genetic architecture such as coat color or horn development. However, there was little evidence for sweeps associated with genes underlying production traits.     

System analysis and nucleic acid sequence banks

The mass of published nucleic acid sequence data has required the design of several computerized data bases. We show that this activity is related to the methodology of System Analysis and that data bases are a means of modeling biological knowledge. As an example, the ACNUC data base we have created is presented.     

Changes in ornithine transcarbamylase activity and protein level during perinatal period in rat liver. Effects of actinomycin D

Ornithine transcarbamylase activity and immunoreactive enzyme level are compared during perinatal period and in adult rat. Ornithine transcarbamylase activity regularly rises during late fetal period and presents a marked increase 24 hours after birth. Immunoreactive enzyme level does not correlate with this developmental pattern. Ornithine transcarbamylase level increases from 0.06 mg on day 19.5 of pregnancy to 0.417 mg/g liver on day 21.5 and remains constant after birth (0.418 mg/g liver). These results suggest that inactive mitochondrial ornithine transcarbamylase accumulates before birth and that the postnatal increase in enzyme activity is mainly associated with an activation. Furthermore, the paradoxical effect of actinomycin D on ornithine transcarbamylase activity is associated with an increase in enzyme level (about 25%).     

Pollinators, flowering phenology and floral longevity in two Mediterranean Aristolochia species, with a review of flower visitor records for the genus

The pollination of Aristolochia involves the temporary confinement of visitors inside the flower. A literature review has shown that some species are visited by one or a few dipteran families, while others are visited by a wider variety of dipterans, but only some of these are effective pollinators. We observed flowering phenology and temporal patterns of pollinator attendance in diverse populations of Aristolochia baetica and A. paucinervis, two species that grow in SW Spain, frequently in mixed populations. The two species had overlapping floral phenologies, extended flowering periods and long-lived flowers. A. baetica attracted a higher number of visitors than A. paucinervis . Drosophilids and, to a lesser extent, phorids, were the main pollinators of A. baetica, whereas in A. paucinervis , phorids were the only pollinators. Attendance to A. paucinervis flowers by phorids in mixed populations was markedly lower than in pure populations. This effect was more evident in years with lower pollinator density. Our results suggest that A. baetica and A. paucinervis may compete for pollinators in mixed populations.