Environmental Pressure May Change the Composition Protein Disorder in Prokaryotes

Many prokaryotic organisms have adapted to incredibly extreme habitats. The genomes of such extremophiles differ from their non-extremophile relatives. For example, some proteins in thermophiles sustain high temperatures by being more compact than homologs in non-extremophiles. Conversely, some proteins have increased volumes to compensate for freezing effects in psychrophiles that survive in the cold. Here, we revealed that some differences in organisms surviving in extreme habitats correlate with a simple single feature, namely the fraction of proteins predicted to have long disordered regions. We predicted disorder with different methods for 46 completely sequenced organisms from diverse habitats and found a correlation between protein disorder and the extremity of the environment. More specifically, the overall percentage of proteins with long disordered regions tended to be more similar between organisms of similar habitats than between organisms of similar taxonomy. For example, predictions tended to detect substantially more proteins with long disordered regions in prokaryotic halophiles (survive high salt) than in their taxonomic neighbors. Another peculiar environment is that of high radiation survived, e.g. by Deinococcus radiodurans. The relatively high fraction of disorder predicted in this extremophile might provide a shield against mutations. Although our analysis fails to establish causation, the observed correlation between such a simplistic, coarse-grained, microscopic molecular feature (disorder content) and a macroscopic variable (habitat) remains stunning.     

Ethanol fermentation by ionically adsorbed Zymomomas mobilis: Environmental effects on cell immobilization

Batch ethanol fermentation by cells of Zymomomas mobilis ATCC 29191, ionically adsorbed on a DEAE-cellulose ion exchanger, was investigated in a stirred fermentor. Adsorption isotherms in different media were determined and used to interpret the effects of the environment on cell immobilization. Other factors affecting cell immobilization during an actual fermentation were studied. Mechanical agitation was found to cause detachment of cells from the ion exchange particles. The results suggest that the amount of cells adsorbed during a fermentation process is different from that found from adsorption isotherm data. Consequently, application of equilibrium adsorption data to actual fermentations should be done with caution.     

Interactions of cultured endothelial cells with TGF-beta, bFGF, PDGF and IGF-I

Endothelial cells in culture synthesize the growth factors transforming growth factor beta (TGF-beta), basic fibroblast growth factor (bFGF), platelet derived growth factor (PDGF) and, perhaps, insulin like growth factor I (IGF-I). We have previously demonstrated that IGF-I and PDGF have both high affinity receptors and stimulate glucose and AIB uptake in the microvessel cells under study and that IGF-I, but not PDGF, has similar high affinity receptors in cultured large vessel endothelial cells. In the present study, cultured bovine endothelial cells were exposed to these four growth factors to determine a) their effects on the acute metabolic processes of neutral amino acid (AIB) and glucose uptake and b) their interactions at the endothelial cell surface. In microvessel endothelial cells, each growth factor stimulated AIB and glucose uptake 2-4 fold whereas in large vessel endothelial cells only bFGF stimulated glucose uptake. Each growth factor had specific high affinity binding to the microvessel cells that was not influenced by the presence of the other growth factors. In large vessel endothelial cells, similar high affinity binding was present only for IGF-I and to a lesser degree TGF-beta. When cells were exposed to a given growth factor for 18 hours, homologous receptor downregulation was observed, with a maximal 60-95% decrease in surface binding. These findings suggest several potential levels of interaction of the growth factors TGF-beta, bFGF, PDGF and IGF-I in cultured vascular endothelial cells.     

Characterization of the central region containing the X-inactivation center and terminal region of the mouse X Chromosome using irradiation and fusion gene transfer hybrids

The irradiation and fusion gene transfer (IFGT) procedure provides a means of isolating subchromosomal fragments for use in the mapping of loci and for cloning probes from a particular area of a chromosome. Using this procedure, two large panels of somatic cell hybrids that contain mouse X Chromosome (Chr) fragments have been generated. These hybrid panels were generated by irradiating the monochromosomal mouse-hamster hybrid HYBX, which retains the mouse X Chr, with either 10 K or 50 K rads of X-irradiation followed by fusion with a recipient Chinese hamster cell line. IFGT hybrids retaining mouse material were generated at high frequency. These hybrids were used to orient loci in the X-inactivation center region that had not been resolvable in our interspecies backcross panel and also to map, within the terminal region of the X Chr, repeat elements detected by the probe p15-4. These hybrids not only complement existing interspecies meiotic mapping panels for the detailed analysis of specific regions of particular chromosomes, but also provide a potential source of material for chromosome-specific probe isolation.     

Genetic and molecular evidence of an X-chromosome deletion spanning the tabby (Ta) and testicular feminization (Tfm) loci in the mouse

A new radiation-induced mutation in the mouse, tabby-25H (Ta25H), has proved to be a deletion which spans both the tabby and testicular feminization (Tfm) loci on the X chromosome. The Ta phenotype closely resembles that of the original TaFa mutation in both the heterozygous and hemizygous conditions but Ta25H/Y animals additionally show the Tfm/Y phenotype, being externally female but possessing abdominally located testes. There is a shortage of both Ta25H/+ and Ta25H/Y classes relative to their normal sibs among the progeny of Ta25H/+ females at weaning age and this was indicated to be due to prenatal or neonatal losses. Exencephaly was observed in some members of both classes prior to birth. Both Ta25H classes tend to be runted at weaning but, remarkably, Ta25H/+ females often show a range of abnormalities not evident in Ta25H/Y animals. When probes for the Zfx, Ccg-1, Phk, and DXPas19 loci, which lie close to Ta, were hybridised to DNAs from Ta25H hemizygotes, the profiles of the X-linked bands were similar to those of control DNAs, suggesting these loci lie outside the deletion. However, a clear absence of an X-linked band was found with human androgen receptor probes, indicating that the Tfm locus is indeed missing. The deletion, therefore, extends a minimum of 1.5 cM and, with its proximal and distal boundaries partially defined, it could be as large as 4 cM. As Ta25H/+ females show the striped X-inactivation coat pattern, the putative X-inactivation centre, Xce, which lies close to Ta, cannot be located within the region deleted. The greasy (Gs) locus similarly appears to lie outside the deletion.     

Separation of isoenzymatic forms of human serum galactosyltransferase by chromatofocusing and isoelectric focusing. Application to cancerology

Chromatofocusing is used to separate the multiple isoenzyme forms of human serum galactosyltransferase. At least 11 major peaks of activity are observed in normal sera, which are eluted between pH 4.3 and 6.9; a fraction of activity is eluted above pH 7.0. The normal patterns are compared with those obtained with sera from cancer patients and with an ascitic fluid. Chromatofocusing appears as resolutive as agarose isoelectric focusing.     

Mass rearing,distribution and colonization ofPteroptrix smithi (Compere) in Israel

Pteroptrix smithi (Compere) is a gregarious internal parasite of the diaspine scaleChrysomphalus aonidum. During the last few years, both host and parasite were mass reared in the laboratory on squash fruits. Releases were made in scaleinfested citrus orchards that were not reached by the parasite’s natural spread. Parasites were recovered from many of the release sites.