Studies on the redox centers of the terminal oxidase from Desulfovibrio gigas and evidence for its interaction with rubredoxin

Rubredoxin-oxygen oxidoreductase (ROO) is the final component of a soluble electron transfer chain that couples NADH oxidation to oxygen consumption in the anaerobic sulfate reducer Desulfovibrio gigas. It is an 86-kDa homodimeric flavohemeprotein containing two FAD molecules, one mesoheme IX, and one Fe-uroporphyrin I per monomer, capable of fully reducing oxygen to water. EPR studies on the native enzyme reveal two components with g values at approximately 2.46, 2.29, and 1.89, which are assigned to low spin hemes and are similar to the EPR features of P-450 hemes, suggesting that ROO hemes have a cysteinyl axial ligation. At pH 7.6, the flavin redox transitions occur at 0 +/- 15 mV for the quinone/semiquinone couple and at -130 +/- 15 mV for the semiquinone/hydroquinone couple; the hemes reduction potential is -350 +/- 15 mV. Spectroscopic studies provided unequivocal evidence that the flavins are the electron acceptor centers from rubredoxin, and that their reduction proceed through an anionic semiquinone radical. The reaction with oxygen occurs in the flavin moiety. These data are strongly corroborated by the finding that rubredoxin and ROO are located in the same polycistronic unit of D. gigas genome. For the first time, a clear role for a rubredoxin in a sulfate-reducing bacterium is presented.

Osteomyelitis secondary to an osteoenteric fistula

Osteomyelitis involving the symphysis pubis is a rare complication of pelvic surgery, and differentiation with osteitis pubis may be difficult. Herein we present a case of a patient in whom a disabling public pain developed 4 months after a radical cystectomy for bladder cancer. His pain was unresponsive to medical and antibiotic therapy and subsequently proved to be caused by public osteomyelitis secondary to a small-bowel fistula precipitated by cancer recurrence.

Clavispora opuntiae and other yeasts associated with the moth Sigelgaita sp. in the cactus Pilosocereus arrabidae of Rio de Janeiro, Brazil

Clavispora opuntiae was the prevalent yeast associated with the feeding sites of Sigelgaita sp. larvae in the cactus Pilosocereus arrabidae. Also associated with this habitat were Candida sonorensis, Pichia cactophila, Pichia barkeri, Candida sp. A, Geotrichum sp., Geotrichum sericeum and the yeast like organisms Prototheca zopfii and Acremonium sp. Atypical yeast biotypes that may represent new species of Pichia, Sporopachydermia and Candida were isolated. Mating types of Clavispora opuntiae were at a ratio 70 h- to 3 h- and reduced levels of sporulation suggested low pressure for sexual reproduction in this habitat. Sigelgaita sp. probably was not an important vector for Clavispora opuntiae because it was not isolated from an adult or eggs of this moth.