Insulin resistance and birth weight

This review article describes the scientific evidence for the relationship between birth weight and insulin resistance. Most studies demonstrate that low birth weight is closely connected to insulin resistance and later development of diabetes type II in adulthood. For this reason it is important for clinicians to focus on the personal history of the patient's birth weight. In patients with low birth weight, primary measures should be taken to prevent the development or progress of insulin resistance, and late consequences like diabetes and atherosclerotic complications.     

Prokaryotic sulfur oxidation

Recent biochemical and genomic data differentiate the sulfur oxidation pathway of Archaea from those of Bacteria. From these data it is evident that members of the Alphaproteobacteria harbor the complete sulfur-oxidizing Sox enzyme system, whereas members of the beta and gamma subclass and the Chlorobiaceae contain sox gene clusters that lack the genes encoding sulfur dehydrogenase. This indicates a different pathway for oxidation of sulfur to sulfate. Acidophilic bacteria oxidize sulfur by a system different from the Sox enzyme system, as do chemotrophic endosymbiotic bacteria.     

Identification of nucleotides critical for activity of the sigmaE-dependent rpoEp3 promoter in Salmonella enterica serovar Typhimurium

We previously described a two-plasmid system for the identification of promoters recognized by Salmonella enterica serovar Typhimurium (S. Typhimurium) sigmaE. The S. Typhimurium sigmaE-dependent rpoEp3 promoter was active in the E. coli two-plasmid system only after arabinose-induced expression of S. Typhimurium rpoE. In the present study, we have exploited this two-plasmid system for the identification of nucleotides critical for activity of the rpoEp3 promoter. A library of randomly mutated DNA fragments containing the rpoEp3 promoter was cloned upstream of a lacZalpha reporter gene and screened for activity in the presence of S. Typhimurium sigmaE. The clones exhibiting reduced LacZ activity were sequenced to identify the mutations. The activity of the mutated rpoEp3 promoters were studied further using a luciferase-based promoter-probe plasmid. All of the important nucleotides of the rpoEp3 promoter (in capital) were located in the -35 (ggAActt) and -10 (TctaA) regions. The critical nucleotides were also the most conserved in known sigmaE-dependent promoters. The study also revealed the importance of the 16-bp spacing between -10 and -35 region, as reducing the spacing to 15-bp greatly reduced activity of the promoter. This method should be generally applicable for the identification of important nucleotides in the cognate promoters of other sigma factors.     

Lysophospholipid receptor-dependent and -independent calcium signaling

Changes in cellular Ca(2+) concentrations form a ubiquitous signal regulating numerous processes such as fertilization, differentiation, proliferation, contraction, and secretion. The Ca(2+) signal, highly organized in space and time, is generated by the cellular Ca(2+) signaling toolkit. Lysophospholipids, such as sphingosine-1-phosphate (S1P), sphingosylphosphorylcholine (SPC), or lysophosphatidic acid (LPA) use this toolkit in a specific manner to initiate their cellular responses. Acting as agonists at G protein-coupled receptors, S1P, SPC, and LPA increase the intracellular free Ca(2+) concentration ([Ca(2+)](i)) by using the classical, phospholipase C (PLC)-dependent pathway as well as PLC-independent pathways such as sphingosine kinase (SphK)/S1P. The S1P(1) receptor, via protein kinase C, inhibits the [Ca(2+)](i) transients caused by other receptors. Both S1P and SPC also act intracellularly to regulate [Ca(2+)](i). Intracellular S1P mobilizes Ca(2+) in intact cells independently of G protein-coupled S1P receptors, and Ca(2+) signaling by many agonists requires SphK-mediated S1P production. As shown for the FcepsilonRI receptor, PLC and SphK may contribute specific components to the overall [Ca(2+)](i) transient. Of the many open questions, identification of the intracellular S1P target site(s) appears to be of particular importance.     

Interaction of helix D of elongation factor Tu with helices 4 and 5 of protein L7/12 on the ribosome

Elongation factor Tu (EF-Tu) promotes binding of aminoacyl-tRNA to the A site of the ribosome. Here, we report the effects of mutations in helix D of EF-Tu and in the C-terminal domain of L7/12 on the kinetics of A-site binding. Reaction rates were measured by stopped-flow and quench-flow techniques. The rates of A-site binding were decreased by mutations at positions 144, 145, 148, and 152 in helix D of EF-Tu as well as at positions 65, 66, 69, 70, 73, and 84 in helices 4 and 5 of L7/12. The effect was due primarily to the lower association rate constant of ternary complex binding to the ribosome. These results suggest that helix D of EF-Tu is involved in an initial transient contact with helices 4 and 5 of L7/12 that promotes ternary complex binding to the ribosome. By analogy to the interaction of helix D of EF-Tu with the N-terminal domain of EF-Ts, the contact area is likely to consist of a hydrophobic patch flanked by two salt-bridges.     

Microhabitat Preferences and Movements of the Weatherfish,Misgurnus fossilis,in a Drainage Channel

Habitat preferences and movements of the weatherfish, Misgurnus fossilis, were studied in a drainage channel of the lower River Havel region (Saxony-Anhalt) from July to November 1995. During summer, adult fish preferred dense vegetation patches (e.g. Elodea canadensis) whereas juveniles preferred the reed zones along the bank lines, characterized by coarse detritus and extremely shallow water depths (<0.1m). All size groups totally avoided open substratum without vegetation structures. In total, 166 weatherfish 14cm were marked individually by injected dyes and their movements were documented by recaptures (recapture rate 29%). Most of the weatherfish showed stationary behaviour or site constancy. The majority of fish (70.1%) were recaptured within ranges of 50m with reference to the first release point. The mean movement distances slightly increased during the search for overwintering habitats in the first weeks of October. Weatherfish stocks in drainage channels of the study area are strongly affected by annual machine weeding due to depletion of suitable microhabitats and direct removal of fish. Alternative maintenance protocols for drainage channels and ditches are proposed.