Identification of the 190 kD microtubule-associated protein in cultured fibroblasts and its association with interphase and mitotic microtubules

We previously investigated the biochemical characteristics of microtubule-associated proteins (MAPs) of the adrenal medulla and adrenal cortex and found that they contain a new kind of MAP with a molecular weight of 190,000 (190 kD MAP) as a major species (Kotani, S., H. Murofushi, S. Maekawa, C. Sato, and H. Sakai. Eur. J. Biochem. 156, 23-29, 1986). We now have used an affinity purified anti-(190 kD MAP) antibody and show by indirect immunofluorescent microscopy the association of this MAP with microtubules in situ in TIG-3 cells (human embryonic lung fibroblasts). The 190 kD MAP was present along the interphase and mitotic microtubules, and there was no marked difference between the staining pattern with anti-tubulin and that with anti-(190 kD MAP) antibodies, evidence that the localization of 190 kD MAP is not restricted to the subset of microtubules. We also isolated MAPs from TIG-3 cells and identified their 190 kD MAP as a major heat-stable component. Several other unidentified polypeptides were recovered in the MAP fraction specifically.     

Correlation between bilayer destabilization and activity enhancement by diacylglycerols in reconstituted Ca-ATPase vesicles

Using the reconstituted Ca-ATPase vesicles as a model system, we demonstrated that the presence of 1,2-dioleoyl-sn-glycerol (diolein) in the membrane introduces a pronounced enhancement in the Ca-transport function of Ca-ATPase, while the 1,2-dipalmitoyl-sn-glycerol (dipalmitin) does not. We also found by both 31P NMR and freeze-fraction electron microscopy that diolein destabilized lipid bilayers to a greater extent than did dipalmitin. We conclude that the tendency of diacylglycerols to destabilize the phospholipid bilayer is related to their capacity to enhance the activity of the membrane calcium pump.     

Skipper impoverishment on large West Mediterranean islands (Lepidoptera Hesperioidea): deterministic,historical and stochastic factors

Biogeographical analyses are applied to skipper (Hesperioidea) presence/absence data from the Western Mediterranean mainland and the three largest islands (Sardinia, Corsica and Sicily) in order to identify potential conservation issues. The analyses performed on species, both collectively and individually, indicate that regional species richness and occurrence in the Mediterranean zone are largely predicted by latitude and area but that islands have impoverished faunas. Several species, predicted to be present on these islands from logistic regression of their continental distributions, are actually absent. The number of species predicted to be present from logistic regression analyses for each island, closely matched the number of species predicted to occur in regional-focused multiple regression analysis. This suggests that missing species have been identified. When compared with species that occur in Sicily and Corsica, the missing species are shown to differ for ecological traits, mainly those linked to altitudinal tolerance. No ecological distinctions were disclosed for Sardinian skippers suggesting a mainly stochastic colonisation. These results, and those from an analogous study carried out on Papilionoidea, point to Hesperioidea having (i) overall more impoverished faunas on islands and (ii) being subject to stochastic or historical colonisation events more than Papilionoidea. Species not predicted to occur on islands based on their mainland distributions and ecological traits, are foci for conservation attention. However, as many species becoming extinct on the islands may be irreplaceable, all species, in particular the Sardinian ones, deserve to be conserved.     

Mutagenicity testing of dichloromethane in short-term mammalian test systems

Several short-term mammalian test systems were used for mutagenicity testing of the organic solvent dichloromethane. The compound was negative in the forward mutation test on the HGPRT locus in Chinese hamster cells and the unscheduled DNA synthesis test in both human and hamster cells. In the test on DNA synthesis inhibition, dichloromethane caused an aspecific inhibition in both human and hamster cells, but in this test the effect did not indicate a DNA-damaging action. A weak positive effect was found in the test on sister-chromatid exchanges in hamster cells.     

Heat stress in the presence of low RNA polymerase activity increases chromosome copy number of Escherichia coli

Summary A temperature shift-up accompanied by a reduction in RNA polymerase activity in Escherichia coli causes an increased rate of initiation leading to a 1.7- to 2.2-fold increase in chromosome copy number. A temperature shift-up without a reduction in polymerase activity induces only a transient non-scheduled initiation of chromosome replication caused by heat shock with no detectable effect on chromosome copy number.