To further understand the ATCase/DHOase bifunctional complex formed in Streptomyces, the genes encoding these and other pyrimidine enzymes were identified and characterized. Polymerase chain reaction (PCR) was utilized in this effort. Primers were constructed by selecting conserved regions of pyrimidine genes from known gene and protein sequences of a wide variety of organisms. These sequences were then optimized to Streptomyces codon usage. PCR products were obtained from internal sites within pyrimidine genes and also from primer combinations of different genes. The size, orientation, and partial sequence of the resulting products shows that Streptomyces has a gene organization of pyrR followed by pyrB, pyrC, carA, carB, and pyrF in an operon similar to that found in other Gram-positive bacteria.

In the United States, biodiversity impact assessment has historically received little attention. Responding in 1993, the Council on Environmental Quality (CEQ) released guidelines on incorporating biodiversity into environmental impact assessment under the National Environmental Policy Act of 1969. The objectives of the study here were to identify the level of documentation of biodiversity impact assessment in sample Environmental Impact Statements (EISs); identify whether in the years following the release of 1993 CEQ guidelines any significant changes have taken place in assessment of biodiversity; identify deficiencies, and if the need exists, formulate appropriate recommendations and approaches for addressing biodiversity in EISs. The study involved a systematic review of 30 EISs published since the release of CEQ guidelines, and five EISs published prior to it. The review involved answering a series of standard questions, which attempted to ascertain the level of biodiversity impacts included in each impact statement. Trends in approaches to biodiversity impact assessment were investigated and deficiencies summarized. The analysis resulted in a series of recommendations for improving the manner in which biodiversity impact assessment can be approached.

Aspartate transcarbamoylase (ATCase) of Streptomyces was characterized and its interaction with other pyrimidine enzymes explored.

The flagellum of Trypanosoma brucei contains a family of antigenically related EF-hand calcium-binding proteins which are called the calflagins. Genomic Southern blots indicated that multiple copies of calflagin genes occur in T brucei. All of the copies were contained in a single 23 kb Xhol-Xhol fragment. Genomic fragments of 2.5 and 1.7 kb were cloned that encoded calflagin sequences. Two new members of the calflagin family were found from genomic clone sequences. The deduced amino acid sequences of the genomic clones showed the calflagin genes were arranged tandemly along the genomic fragments and were similar to previously described calflagins. The calflagin genes were related by two unrelated 3' flanking sequences. An open reading frame that was unrelated to any calflagin was found at the 5' end of the 2.5 kb genomic fragment. Each encoded protein (~24,000u) contained three EF-hand calcium-binding motifs and one degenerate EF-hand motif. In general, variability among the T. brucei calflagins is greater than related proteins in T. lewisii and T. cruzi. This variability results from amino acid substitutions at the amino and carboxy termini, and duplication of internal segments.

Carbonic anhydrase is a ubiquitous zinc-metalloenzyme that catalyzes the interconversion of carbon dioxide and carbonate and has been found to play a wide range of roles in animals, plants and bacteria. Cotton genomic and cDNA libraries were screened for the plastidial isoform of carbonic anhydrase. The nucleotide sequences of two 1.2 Kb partial cDNA clones were determined. These clones exhibit high homology to carbonic anhydrases from other dicot plants and possess all the expected peptide motifs. For example, serine and threonine rich chloroplastic targeting peptide and conserved zinc binding residues are both present. These clones were utilized to isolate two carbonic anhydrase genes that were shown to encode different isoforms by PCR and RFLP analysis.

Many historians have acknowledged the temptation to portray people as they see themselves and wish to be seen, blending history and ideology. The result is "mythistory." Twentieth century Texas writers and historians, remarking upon the exceptional durability of the Texas mythistory that emerged from the nineteenth century, have questioned its resistance to revision throughout the twentieth century. By placing the writing of Texas history within the context of American and European intellectual climates and history writing generally, from the close of the eighteenth century to the beginning of the twentieth, it is possible to identify a pattern that provides some insight into the popularity and persistence of Texas mythistory.