Evaluation of ITS PCR and RFLP for Differentiation and Identification of Brewing Yeast and Brewery 'Wild' Yeast Contaminants.

A reference library of ITS PCR/RFLP profiles was collated and augmented to evaluate its potential for routine identification of domestic brewing yeast and known 'wild' yeast contaminants associated with wort, beer and brewing processes. This library contains information on band sizes generated by restriction digestion of the ribosomal RNA-encoding DNA (rDNA) internal transcribed spacer (ITS) region consisting of the 5.8 rRNA gene and two flanking regions (ITS1 and ITS2) with the endonucleases CfoI, HaeIII, HinfI and includes strains from 39 non-Saccharomyces yeast species as well as for brewing and non-brewing strains of Saccharomyces. The efficacy of the technique was assessed by isolation of 59 wild yeasts from industrial fermentation vessels and conditioning tanks and by matching their ITS amplicon sizes and RFLP profiles with those of the constructed library. Five separate, non-introduced yeast taxa were putatively identified. These included Pichia species, which were associated with conditioning tanks and Saccharomyces species isolated from fermentation vessels. Strains of the lager yeast S. pastorianus could be reliably identified as belonging to either the Saaz or Frohberg hybrid group by restriction digestion of the ITS amplicon with the enzyme HaeIII. Frohberg group strains could be further sub-grouped depending on restriction profiles generated with HinfI.

Petite mutation in aged and oxidatively stressed ale and lager brewing yeast.

AIMS: To determine the role of oxidative stress and chronological ageing on the propensity of brewing yeast strains to form respiratory deficient 'petites'. METHODS AND RESULTS: Four industrial yeast strains (two ale and two lager strains) were exposed to oxidative stress in the form of H(2)O(2) (5 mmol l(-1)) for two hours. Cell viability and occurrence of petites were determined by the slide culture and TTC-overlay techniques, respectively. Increases in petite frequency were observed but only in those strains sensitive to oxidative stress. Chronological ageing under aerobic conditions led to an increase in petites in strains sensitive to oxidative stress. No such increase was observed under anaerobic conditions. CONCLUSION: Ageing may contribute to mitochondrial DNA damage and increase the propensity of brewing yeast cells to become respiratory deficient. Tolerant strains may be less likely to generate petites as a result of serial re-pitching. SIGNIFICANCE AND IMPACT OF THE STUDY: Continuous re-use of brewing yeast is associated with an increase in the frequency of petites within brewery yeast slurries, a phenomenon resulting in reduced fermentative capacity. The cause of petite generation during brewery handling is unknown. We show that endogenous oxidative stress has the potential to generate petites within brewing yeast populations.

Mesenchymal dysplasia of the placenta.

Placental mesenchymal dysplasia is a rare human placental disorder in which the placenta is enlarged and contains cystic villi and dilated vasculature. It is important to recognize this disorder because it may mimic a partial hydatidiform mole. In contrast to a partial mole, mesenchymal dysplasia may coexist with a normal fetus. This case occurred at the Madigan Army Medical Center in Tacoma, Washington, in June 2002.

Tissue distribution of primaquine in the rat.

The distribution of primaquine was measured in seven rat tissues at 15-180 min after the intraperitoneal injection of the antimalarial 8-aminoquinoline. The half-life of unmetabolized primaquine was 4.0 h in lung, 1.7-1.9 h in blood, spleen, kidney and heart, and 1.2 h in liver. At each interval, the concentrations of unmetabolized primaquine were (in order): lung greater than liver, kidney, spleen greater than heart greater than brain greater than or equal to blood. At 3 h after the injection of [6-O-methyl-3H]primaquine, unmetabolized primaquine constituted 10% of the total 3H in blood and 40-60% of the total 3H in liver, brain, heart and kidney.

Inhibition of precursor incorporation into nucleic acids of mammalian tissues by antimalarial aminoquinolines.

1 Chloroquine, primaquine and ethidium inhibitied thymidine incorporation into deoxyribonucleic acid of rat tissues when administered concurrently with the labelled precursor. 2 Chloroquine and primaquine inhibited the incorporation of uridine and adenine, but not orotate, into various ribonucleic acid fractions of liver of rats and mice. These drugs had no effect on leucine incorporation into hepatic protein in rats or mice. 3 Although chloroquine and primaquine are active against different stages in the life cycle of the malarial parasites, the two aminoquinolines exert similar effects in rodent tissues.