Characterization of the cys gene locus from Allochromatium vinosum indicates an unusual sulfate assimilation pathway.

Homologues of the genes cysB, cysI, cysH, cysD, cysN, and selD were identified in the genome of the phototrophic purple sulfur bacterium Allochromatium vinosum (formerly Chromatium vinosum). On the basis of amino acid comparisons these genes encode a ferredoxin-dependent siroheme-sulfite reductase (CysI), a plant-type assimilatory APS reductase without thioredoxin domain (CysH), the two different subunits of heterodimeric ATP sulfurylase (CysDN), a transcriptional regulator (CysB) and a selenophosphate synthase (SelD). cysIHDN appear to form an operon and are preceded by cysB which is transcribed in the opposite direction. SelD is situated downstream of cysN and transcribed divergently to cysIHDN. The lack of a gene for APS kinase and presence of a gene for an assimilatory APS reductase implies that assimilatory sulfate reduction in A. vinosum proceeds along the pathway suggested for higher plants without intermediary formation of PAPS. Two completely separate pathways involving specialized enzymes are used for assimilatory sulfate reduction and dissimilatory sulfur oxidation in A. vinosum. The presence of cysB indicates that the genes for assimilatory sulfate reduction are expressed only in the absence of reduced sulfur compounds.

Dissimilatory ATP sulfurylase from the hyperthermophilic sulfate reducer Archaeoglobus fulgidus belongs to the group of homo-oligomeric ATP sulfurylases.

In the hyperthermophilic sulfate reducer Archaeoglobus fulgidus DSM 4304T, two open reading frames (sat and ORF2) are located upstream of the aprBA genes encoding adenosine-5'-phosphosulfate (APS) reductase. sat-ORF2-aprBA probably form a transcriptional unit, since sat is preceded by putative promoter sequences and termination signals are found downstream of aprA. While the 117-residue ORF2 product does not show significant similarity to known proteins, the 456-residue, 52.78-kDa, sat-encoded polypeptide exhibits similarity to the homo-oligomeric adenosine triphosphate (ATP) sulfurylases from sulfur-oxidizing bacteria and from sulfate-assimilating bacteria and eukaryotes. Functional overexpression of sat in Escherichia coli proved that the encoded protein acts as an ATP sulfurylase. The recombinant protein was purified to homogeneity and found to be a homo-dimer. Comparison of sulfate and thiosulfate grown A. fulgidus revealed that ATP sulfurylase and APS reductase are constitutive enzymes. Distance matrix analyses allowed insights into the evolution of prokaryotic ATP sulfurylases.

The World Medical Association and medical ethics.

KIE: The author, Secretary General of the World Medical Association (WMA), wrote this letter on the occasion of an audience with Pope John Paul II during the WMA's General Assembly. The Association, historically a proponent of ethical behavior in medicine, is especially concerned with the growing erosion of respect for and defense of the individual in the medical setting. Social benefits favoring the healthy are often provided at the expense of adequate health care for the sick. The Association is resolved to support the health care rights of the individual.^ieng

The management of abdominal wall stomata: skin protection, peristomal wound healing and support for the collecting bag. A multi-center study.

The specific properties of Stomahesive tested in 116 stomal and 20 fistulous patients render it really useful in stomatherapy where it increases the comfort of the patients: 1. it offers an excellent peristomal skin protection whatever the nature of the stoma or origin of the fistula; 2. it promotes rapid healing of skin lesions, even in ileostomy, transverse colostomy, ureterostomy and fistula patients; 3. it ensures an effective degree of impermeability; 4. it provides a large base for adhesion of the collecting bag; 5. it can be kept on for about 6 days in most cases; 6. The local tolerance is excellent (Acta chir. belg., 1977, 76, 533-537).