Fluorescence studies of the effect of pH, guanidine hydrochloride and urea on equinatoxin II conformation.

The solvent denaturation of equinatoxin II (EqTxII) in aqueous solutions of urea, guanidine hydrochloride (Gu-HCl) and at various pH values was examined by monitoring changes in the protein intrinsic emission fluorescence spectra and in the fluorescence spectra of the added external probe ANS. It has been observed that EqTxII denaturation is reflected in a strong red shift of intrinsic fluorescence emission maxima accompanied by a simultaneous decrease in fluorescence intensity and that guanidine hydrochloride is significantly more powerful denaturant than urea or changing of pH. Comparison of intrinsic fluorescence spectra of EqTxII denatured by one of the three denaturing agents has shown that the fully denatured states of the protein in Gu-HCl and urea are similar and substantially different from those induced by changing of pH.

Studies of safety, infectivity and immunogenicity of a new temperature-sensitive (ts) 51-1 strain of Salmonella typhi as a new live oral typhoid fever vaccine candidate.

This report describes the results of a phase 1 study evaluating the safety, infectivity, and immunogenicity of a new live oral Salmonella typhi temperature-sensitive (ts) 51-1 typhoid fever vaccine in the human. Three normal male subjects aged 23-32 years received three oral doses of S. typhi ts 51-1, each dose containing 10(9) organisms.

Growth response of several Candida albicans strains to inhibitory concentrations of heavy metals.

Prolonged exposure of several Candida albicans strains to inhibitory concentrations of Cd, Cu, or Zn resulted in the appearance of resistant colonies at frequencies and with kinetics significantly different than expected based solely upon the predicted spontaneous mutation rate. Characteristics of the response included: (i) a delay usually of 4-10 days in the emergence of the first resistant colonies; (ii) continued accumulation of resistant colonies for a minimum of 21 days after initial exposure to selection; and (iii) final mutation frequencies ranging from 7.0 x 10(-6) to 9.

Phenotypic variation of a virulent Candida albicans strain and two spontaneous, relatively avirulent mutant strain derivatives.

The effect of media and temperature of incubation on colony phenotype of Candida albicans strain 4918, and two relatively avirulent mutant strains, designated 4918-2 and 4918-10, has been investigated. In addition, the strains were characterized on the basis of morphotyping pattern. Colony phenotypes were determined for cultures grown on either Lee's medium supplemented with arginine and zinc, or M63 medium supplemented with casamino acids.

Complementary transcripts from two genes necessary for normal meiosis in the yeast Saccharomyces cerevisiae.

The SPO12 gene, which is required for meiosis I chromosome division during sporulation of the yeast Saccharomyces cerevisiae, has been isolated. DNA sequencing has identified an open reading frame of 173 codons that encodes the putative SPO12 protein and has no significant sequence similarities to known genes. The last 15 amino acids of this putative protein have a high negative charge, which appears to be required for function.