The cellular control enzyme polyADP ribosyl transferase is eliminated in cultured Fanconi anemia fibroblasts at confluency

Fanconi anemia (FA) is a hereditary disease of unknown pathogenic mechanisms, although mutations in seven different genes can be causative. Six of these genes have been cloned and sequenced. Only slight homology to the DNA of any other known gene has been found with the exception of FANCG which is identical to XRCC9. The function of these genes, including XRCC9, is presently unknown. Since pADP ribosyl transferase (pADPRT) plays a role in apoptosis, and apoptosis is affected in FA cells, we studied the correlation between pADPRT and FA cells. We reinvestigated the previously reported lack of pADPRT activity in fibroblasts from patients with Fanconi anemia. Here we describe the role of the lower redox potential of FA cells and demonstrate that this is an efficient strategy in the prevention of cell death due to the lack of energy under oxidative stress. This strategy is advantageous for the cells under the nonreplicative condition of confluency in which the risk of mutation is low and the prevention of apoptosis permits cell survival. pADPRT is not diminished to the same extent in all complementation groups of FA. It is prominent in FANCA, FANCG and FANCF cells, indicating that these genes control pADPRT diminution. Our experiments suggest that the pADPRT level is linked with the oxidoreduction reactions seen in FA.     

Conserved and divergent functions of Drosophila atonal,amphibian, and mammalian Ath5 genes

Insect and vertebrate eyes differ in their formation, cellular composition, neural connectivity, and visual function. Despite this diversity, Drosophila atona and its vertebrate Ortholog in the eye, Ath5, each regulate determination of the first retinal neuron class-R8 photo-receptors and retinal ganglion cells (RGCs)-in their respective organisms. We have performed a cross-species functional comparison of these genes. In ato mutant Drosophila, ectopic Xenopus Ath5 (Xath5) rescues photoreceptor cell development comparably with atonaI. In contrast, mouse Ath5 (Math5) induces formation of very few ommatidia, and most of these lack R8 cells. In the developing frog eye, ectopic atonal, like Xath5, promotes the differentiation RGCs. Despite strong conservation of atonaI, Xath5, and Math5 structure and shared function, other factors must contribute to the species specificity of retinal neuron determination. These observations suggest that the atonaI family may occupy a position in a gene hierarchy where differences in gene regulation or function can be correlated with evolutionary diversity of eye development.     

A phospholipase D-dependent process forms lipid droplets containing caveolin,adipocyte differentiation-related protein,and vimentin in a cell-free system

We developed a microsome-based, cell-free system that assembles newly formed triglyceride (TG) into spherical lipid droplets. These droplets were recovered in the d 相似文献   

Metabolic efficiency of liver mitochondria in rats with decreased thermogenesis

We have studied changes in hepatic mitochondrial efficiency induced by 24-h fasting or acclimation at 29 degrees C, two conditions of reduced thermogenesis. Basal and palmitate-induced proton leak, which contribute to mitochondrial efficiency, are not affected after 24-h fasting, when serum free triiodothyronine decreases significantly and serum free fatty acids increase significantly. In rats at 29 degrees C, in which serum free triiodothyronine and fatty acids decrease significantly, basal proton leak increases significantly, while no variation is found in palmitate-induced proton leak. The present results indicate that mitochondrial efficiency in the liver is not related to a physiological decrease in whole body thermogenesis.     

The taxonomic status of Corethromyces bicolor from New Zealand, as inferred from morphological, developmental, and molecular studies

Due to the absence of antheridial characters in collected material the precise placement of Corethromyces bicolor has remained troublesome up until now. Recent re-examination of receptacular and appendage characters present in the holotype led to its transfer to the genus Mimeomyces. Fresh collections of this fungus have provided the opportunity to re-assess its taxonomic position. Based on a combination of morphological and molecular characters, this species is re-instated within the genus Corethromyces.     

The initiation factor eIF4A is involved in the response to lithium stress in Saccharomyces cerevisiae

A gene, TIF2, was identified as corresponding to the translation initiation factor eIF4A and when overexpressed it confers lithium tolerance in galactose medium to Saccharomyces cerevisiae. Incubation of yeast with 6 mm LiCl in galactose medium leads to inhibition of [(35)S]methionine incorporation. By polysome analysis we show that translation is inhibited by lithium at the initiation step, accumulating 80 S monosomes. We further show by immunoblot analysis that when cells are incubated with lithium eIF4A does not sediment with ribosomal subunits. Overexpression of TIF2 overcomes inhibition of protein synthesis and restores its sedimentation with the initiation complex. In vivo, eIF4A is induced by lithium stress. We have shown previously that lithium is highly toxic to yeast when grown in galactose medium mainly due to inhibition of phosphoglucomutase, an enzyme responsible for the entry of galactose into glycolysis. We show that conditions that revert inhibition of phosphoglucomutase also revert inhibition of protein synthesis. Interestingly, glucose starvation leads to loss of polysomes but not to dissociation of eIF4A from the preinitiation complexes. Overexpression of SIT4, a protein phosphatase related to the TOR kinase pathway, reverts inhibition of protein synthesis by lithium and association of eIF4A with the initiation complex.     

Susceptibility of Biomphalaria straminea (Dunker, 1848) from Serra da Mesa Dam,Goiás,Brazil to infection with three strains of Schistosoma mansoni Sambon, 1907

Ecological changes from water resources development projects often affect the epidemiology of water-associated diseases. In order to investigate the occurrence and distribution of freshwater snails of medical and veterinary importance in the area of influence of the Serra da Mesa Hydroelectric a survey has been performed since 1997 and revealed the occurrence of well-established populations of Biomphalaria straminea (Dunker, 1848) in the 8 municipalities surrounding the lake. Areas of epidemiologic risk for schistosomiasis were selected and studies of parasite-mollusc compatibility were undertaken using specimens from 19 populations of B. straminea and 3 strains (CM, EC and PB) originally isolated from B. straminea. Among 1,135 specimens used 15 became infected (infection index of 1.3%) and 8 populations were susceptible to the schistosome strains: B. straminea from Campinorte (Castel?o, susceptible to CM and EC strains, and Planeta Agua, EC strain), Colinas (Tocantinzinho river, CM and EC strains), Mina?u (Canabrava river, EC strain), Niquelandia (Codemin, CM and PB strains, and Almas river, CM strain), Urua?u (touristic area, PB strain) and Santa Rita do Novo Destino (Maranh?o river, CM and EC strains). These results, associated with marked social and ecological changes occurred, strongly suggest the possibility of B. straminea coming to act as a vector of schistosomiasis in the studied area.