Assembly and genetics of spore protective structures

The sporulation program in Bacillus subtilis ends in the formation of a highly resistant endospore that can withstand extremes of heat, mechanical disruption, ultraviolet irradiation, lytic enzymes and chemical attack. These properties are attributed mainly to the unique structure of spore coat and cortex, as well as to the physical state of the spore cytoplasm. The outermost layer of the spore, called the coat, has two morphologically distinct sublayers: an electron-dense outer coat and an electron-translucent inner coat. The coat is composed of more than 2 dozen proteins of varying size. Many coat genes and coat proteins have been isolated and characterized in detail, and studies of these have identified proteins with important roles in coat assembly, resistance and spore germination. We describe here characteristics of the coat proteins and propose a model for coat assembly based on recent work.     

Modulation of protein biophysical properties by chemical glycosylation: biochemical insights and biomedical implications

Glycosylation constitutes one of the most important posttranslational modifications employed by biological systems to modulate protein biophysical properties. Due to the direct biochemical and biomedical implications of achieving control over protein stability and function by chemical means, there has been great interest in recent years towards the development of chemical strategies for protein glycosylation. Since current knowledge about glycoprotein biophysics has been mainly derived from the study of naturally glycosylated proteins, chemical glycosylation provides novel insights into its mechanistic understanding by affording control over glycosylation parameters. This review presents a survey of the effects that natural and chemical glycosylation have on the fundamental biophysical properties of proteins (structure, dynamics, stability, and function). This is complemented by a mechanistic discussion of how glycans achieve such effects and discussion of the implications of employing chemical glycosylation as a tool to exert control over protein biophysical properties within biochemical and biomedical applications. Received 15 December 2006; received after revision 28 March 2007; accepted 25 April 2007     

A prostaglandin-like activity in small intestine and postirradiation gastrointestinal syndrome

Summary A correlation between the postirradiation increase of the small intestine motility and the prostaglandin-like activity in this organ during gastrointestinal syndrome was observed. Indomethacin decreased the elevated motility of intestine and reduced the prostaglandin-like activity in this syndrome.Acknowledgments. The work was supported by the Polish Academy of Sciences.     

Triphasic vascular effects of thiol compounds and their oxidized forms on dog coronary arteries

The vascular effects of 2-mercaptoethanol, cysteamine, L-cysteine, glutathione (GSH), cystamine and oxidized GSH (GSSG) on the isometric tension of isolated dog coronary arterial strips were examined, and these effects were compared with the triphasic response induced by dithiothreitol (DTT); a rapid and weak contraction (phase A), an intervening slow relaxation (phase B) and a slowly-developing strong contraction (phase C) which we previously reported. The responses of the arteries induced by 2-mercaptoethanol, cysteamine and L-cysteine consisted of phases A, B and C. The order of contractile potency (ED₅₀ of phase C) was DTTL-cysteine>2-mercaptoethanolcysteamine, while the order of relaxant potency (ED₅₀ of phase B) was DTT>cysteamine2-mercaptoethanol. GSSG and cystamine mainly produced relaxation, which corresponded to phase B. The phase C contraction was specific to the reduced forms of thiols, except for GSH, which produced only relaxation. The participation of endothelial cells was not essential for the contracting or relaxing effects of the thiol compounds. The phase C contraction was depressed by W-7, a calmodulin antagonist, while phase A was not. Therefore calmodulin-dependent protein kinases may participate in phase C, not in phase A.     

Maternal vitamin A restriction alters biochemical development of the brain in rats

Summary The biochemical development of the fetal brain in relation to maternal vitamin A restriction was studied in rats. The vitamin A status of pregnant rats was varied by supplying low, medium and adequate amounts (6, 40, and 100 g retinol/day/kg body weight, respectively) of vitamin A during pregnancy and suckling. The maternal vitamin A restriction caused an altered brain development in terms of tissue weight, DNA, RNA and protein levels, and biosynthesis of DNA and protein from [³H]-thymidine and [³H]-leucine, respectively. A dose-dependent effect of maternal vitamin A restriction on the metabolism of DNA, RNA and protein was noticed in the developing fetal brain of rats.     

Granuloma formation in rat liver after hepatic vein ligation

Summary After occlusion of the hepatic vein draining 1 lobe of the rat liver, macrophage granulomas develop which are reproducible and apparently related to a heat-labile macrophage mobilising factor.     

ARSACS, a spastic ataxia common in northeastern Québec, is caused by mutations in a new gene encoding an 11.5-kb ORF

Autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS or SACS) is an early onset neurodegenerative disease with high prevalence (carrier frequency 1/22) in the Charlevoix-Saguenay-Lac-Saint-Jean (CSLSJ) region of Quebec. We previously mapped the gene responsible for ARSACS to chromosome 13q11 and identified two ancestral haplotypes. Here we report the cloning of this gene, SACS, which encodes the protein sacsin. The ORF of SACS is 11,487 bp and is encoded by a single gigantic exon spanning 12,794 bp. This exon is the largest to be identified in any vertebrate organism. The ORF is conserved in human and mouse. The putative protein contains three large segments with sequence similarity to each other and to the predicted protein of an Arabidopsis thaliana ORF. The presence of heat-shock domains suggests a function for sacsin in chaperone-mediated protein folding. SACS is expressed in a variety of tissues, including the central nervous system. We identified two SACSmutations in ARSACS families that lead to protein truncation, consistent with haplotype analysis.