No apparent repression of pyr gene expression in Pseudomonas aeruginosa is observed upon addition of exogenous pyrimidines to the growth medium. Upon introduction of the subcloned Escherichia coli pyrBI genes for aspartate transcarbamoylase (ATCase) into a P. aeruginosa pyrB mutant strain, repression was observed in response to exogenously fed pyrimidine compounds. The results proved that it is possible to bring about changes in pyrimidine nucleotide pool levels and changes in transcriptional regulation of gene expression as a result. Thus, the lack of regulatory control in P. aeruginosa pyr gene expression is not due to an inability to take up and incorporate pyrimidine compounds into metabolic pools, or to an inability of the RNA polymerase to respond to regulatory sequences in the DNA but is probably due to a lack of specific regulatory signals in the promoter of the genes themselves.

Sucrose fading was used to initiate self-administration of ethanol on an FR4 schedule in male Fischer 344 rats. Rats showed low response rates for ethanol alone. After administration of liquid diet containing ethanol, ethanol intake increased over levels prior to administration of the liquid diet. In situ hybridization compared mRNA for the inducible or constitutive 70 kD heat shock proteins in ethanol and nonethanol rats. Both inducible and constitutive mRNAs were found in nonethanol and ethanol tissues. In peripheral organs, radiolableling was higher in ethanol tissue. In brain regions, nonethanol tissues showed higher radiolabeling.

Chorine is used by the Village Creek Waste Water Treatment Plant to kill pathogenic microorganisms prior to discharge of the effluent into the Trinity River. The residual chlorine in the river impacted aquatic life prompting the U.S. Environmental Protection Agency in December 1990 to require dechlorination using sulfur dioxide. One pre-dechlorination and four post-dechlorination assessments of phytoplankton, periphyton, and zooplankton communities were conducted by the Institute of Applied Sciences at the University of North Texas. Dechlorination had no effect on the phytoplankton community. The periphyton community exhibited a shift in species abundance with a more even distribution of organisms among taxa. No change occurred in zooplankton species abundance, however, there was a decrease in zooplankton density following dechlorination.