Bacillus subtilis genome project: cloning and sequencing of the 97 kb region from 325° to 333deg;

In the framework of the European project aimed at the sequencing of the Bacillus subtilis genome the DNA region located between gerB (314°) and sacXV (333°) was assigned to the Institut Pasteur. In this paper we describe the cloning and sequencing of a segment of 97 kb of contiguous DNA. Ninety-two open reading frames were predicted to encode putative proteins among which only forty-two were found to display significant similarities to known proteins present in databanks, e.g. amino acid permeases, proteins involved in cell wall or antibiotic biosynthesis, various regulatory proteins, proteins of several dehydrogenase families and enzymes II of the phosphotransferase system involved in sugar transport. Additional experiments led to the identification of the products of new B. subtilis genes, e.g. galactokinase and an operon involved in thiamine biosynthesis.     

Potassium and sodium ions in the glycerinated skeletal muscle. Distribution changes induced by adenosine triphosphate and nondissociable anesthetic substances.

Investigation of the ionic behavior of glycerinated muscle fibers showed that the residual structures of this biologic cellular material, lacking functional membranes, are able to discriminate between alkaline ions. The characteristics of the ionic selectivity of the glycerinated fibers change with their functional state and with the presence in the medium of certain nonionic substances. Among the more important features of ionic distribution between the membrane-free fibers and the medium are the following: (1) There is evident adsorption of potassium on the fibers, in the absence of ATP. (2) This adsorption increases in contraction and decreases in relaxation. (3) At high ionic concentrations, in contrast to what occurs at low potassium concentrations, the glycerinated muscle prefers sodium to potassium, but even under these conditions both ions are accumulated in the fibers to far greater levels than in the medium. This strongly suggests a Donnan ionic equilibrium developing parallel to the adsorption process. (4) Nonionic substances of the general anesthetic group markedly alter the ionic selectivity of the glycerinated fibers, probably by their action on the water's physical state. A mechanism is proposed for the observed ionic adsorption specific of the muscle-a mechanism in which actin-myosin coupling plays the cardinal adsorption role. In the general interpretation of the data a synthetic concept is advanced according to which an entire set of processes and factors concurs with the distribution of ions between the muscle and the medium.     

Biogeography of the ecosystems of the healthy human body

Background

Characterizing the biogeography of the microbiome of healthy humans is essential for understanding microbial associated diseases. Previous studies mainly focused on a single body habitat from a limited set of subjects. Here, we analyzed one of the largest microbiome datasets to date and generated a biogeographical map that annotates the biodiversity, spatial relationships, and temporal stability of 22 habitats from 279 healthy humans.

Results

We identified 929 genera from more than 24 million 16S rRNA gene sequences of 22 habitats, and we provide a baseline of inter-subject variation for healthy adults. The oral habitat has the most stable microbiota with the highest alpha diversity, while the skin and vaginal microbiota are less stable and show lower alpha diversity. The level of biodiversity in one habitat is independent of the biodiversity of other habitats in the same individual. The abundances of a given genus at a body site in which it dominates do not correlate with the abundances at body sites where it is not dominant. Additionally, we observed the human microbiota exhibit both cosmopolitan and endemic features. Finally, comparing datasets of different projects revealed a project-based clustering pattern, emphasizing the significance of standardization of metagenomic studies.

Conclusions

The data presented here extend the definition of the human microbiome by providing a more complete and accurate picture of human microbiome biogeography, addressing questions best answered by a large dataset of subjects and body sites that are deeply sampled by sequencing.