Putrescine Detected in Strains of Staphylococcus aureus.

Most forms of life, including the archaea, bacteria, and eukaryotes synthesize the polyamine putrescine. Although putrescine is widely distributed, several Gram-positive bacteria, including Staphylococcus aureus (S. aureus), appear to be the exceptions. We report here that strains of S. aureus can produce the polyamine putrescine, as well as the derivative N-acetyl-putrescine. Three strains of S. aureus from the American Type Culture Collection (ATCC), one strain listed in the National Center for Biotechnology Information (NCBI) database, whose genomic sequence is well defined, and well as eight strains from S. aureus-induced brain abscesses of individual patients from multiple geographic locations were evaluated. Each strain was grown in complete chemically defined medium (CDM) under stringent conditions, after which the partially purified conditioned medium (CM) was analyzed by mass spectroscopy (MS), and the data were reported as the ratio of experimental results to controls. We confirmed the synthesis of putrescine by S. aureus by using 13C/15N-labeled arginine as a tracer. We found that agmatine, N-acetyl-putrescine, ornithine, citrulline, proline, and NH3 were all labeled with heavy isotope derived from 13C/15N-labeled arginine. None of the strains examined produced spermine or spermidine, but strains from either ATCC or human brain abscesses produced putrescine and/or its derivative N-acetyl-putrescine.

Vitamins A, C, and E May Reduce Intestinal 210Po Levels after Ingestion.

Damage to the gut mucosa is a probable contributory cause of death from ingested Po. Therefore, medical products are needed that can prevent, mitigate, and/or repair gastrointestinal (GI) damage caused by high-LET radiation emitted by Po. The present studies investigated the capacity of a diet highly enriched with vitamins A, C, and E (vitamin ACE) to protect against intestinal mucosal damage indicated by functional reductions in nutrient transport caused by orally ingested Po. Mice were gavaged with 0 or 18.5 kBq Po-citrate and fed a control or vitamin ACE-enriched diet (the latter beginning either 96 h before or immediately after gavage). Mouse intestines significantly retained Po on day 8 post-gavage. The concentration of Po in intestinal tissues was significantly (p<0.05) lower in all vitamin ACE groups compared to control. There were borderline significant Po-induced reductions in intestinal absorption of D-fructose. The combination of vitamins A, C, and E may reduce Po incorporation in the intestines when given before, or enhance decorporation when provided after, Po gavage.

Oswald T. Avery: Nbel Lureate or noble luminary?

In 1944, Oswald T. Avery and his associates reported that DNA was the chemical substance acting to genetically transform species of pneumococcal bacteria. Many believe that Avery warranted the Nobel Prize for this discovery. Avery's work is evaluated here in light of the Nobel archives, which have made public the names of those who nominated Avery for this award and the basis for each of the nominations. Based on the archival record, it seems that key biological chemists "were not convinced by Avery's claim that DNA was the basis of heredity, that no geneticists nominated Avery, and that most nominators overlooked Avery's work on DNA in favor of his work on the immunogenicity of the bacterial capsule. Three critical scientific factors that adversely affected acceptance of Avery's work were the possibility of protein contamination of DNA, the role of DNA transformation limited to a few species of bacteria, and the possibility that DNA was acting as a chemical mutagen on the true genetic substance. In addition, Avery's own idiosyncratic behavior may have unintentionally confounded acceptance of his groundbreaking discovery.

Conditioned medium from Listeria innocua stimulates emergence from a resting state: not a response to E. coli quorum sensing autoinducer AI-2.

The lag phase of the bacterial growth curve is an important determinant in speeding the detection of pathogens. It is affected by many factors including the prevailing growth environment and inoculum size, as well as specific signal molecules. The elucidation of growth-regulating signal molecules is further facilitated by culturing cells in defined growth media. In this study, a defined medium capable of supporting growth of Listeria innocua at similar levels as obtained using a complex brain heart infusion (BHI) media was developed. Further, the effects of conditioned medium (CM) on population lag time of L. innocua was investigated using a rapid parallel approach (with an automated microtiter plate reader). Importantly, the lag phase was shortened by up to approximately 50% by the addition of CM from L. innocua cultures obtained late in the exponential phase. Finally, while L. innocua were found to secrete bacterial signaling autoinducer, AI-2, tests using Escherichia coli based CM having a 90-fold difference in AI-2 level suggested that the observed decrease in lag phase was not due to E. coli-derived AI-2 and was instead due to elements specific to L. innocua. These findings indicate secreted signal molecules may be found in CM that speed detection of L. innocua.