A 2 x 2 factorial design investigated effects of sediment nitrogen and water potassium levels on autofragment production. Reduced nitrogen levels significantly increased autofragment production whereas potassium levels did not significantly alter production. Up to 50% of autofragment production abscised from parent plants grown under low nitrogen conditions compared to 12% or less under high nitrogen conditions.

Bacterial aspartate transcarbamoylases (ATCase's) are divided into three classes that correspond to taxonomic relationships within the bacteria. The opportunistic pathogen Moraxeila catarrhalis has undergone several reclassifications based on traditional microbiological criteria. The previously uncharacterized ATCase from M. catarrhalis was purified to homogeneity and its chemical properties characterized. The ATCase from M. catarrhalis is a class C ATCase with an apparent molecular mass of 480-520 kDa. The M. catarrhalis ATCase is a dodecomer composed of six 35 kDa polypeptides and six 45 kDa polypeptides. The enzyme has an unusually high pH optimum of greater than pH 10. The enzyme exhibited hyperbolic kinetic with a Km for aspartate of 2 mM. A single, separate 78 kDa dihydroorotase from M. catarrhalis was identified and it was not associated with ATCase. These data support the reclassification of M. catarrhalis out of the Neisseriaceae family.

Recent studies regarding research on oral microorganisms and the oral diseases are presented. The normal flora of the mouth and the oral environment are first described. Dental plaque and dental caries are primary causes of oral disease. Streptococcus mutans is the major contributor in the initiation and progression of dental caries. Lactobacillus, Actinomyces, and Veillonella are other genera of bacteria linked to dental caries. Periodontitis and gingivitis are periodontal diseases that are caused by oral microorganisms. New research has indicated that various antimicrobial agents and techniques to eliminate or lessen the severity of periodontal diseases. Premature delivery of low birth weight babies in pregnant women has been strongly linked to periodontal disease. Present and future microbiological tests are available to easily determine the causative organisms for most oral diseases that help in diagnosis and treatment of a particular disease.

The lumbar motor activity in isolated spinal cords of 72 postnatal Balb/C mice aged 2, 5, 10 and 21 days (PN2-21) was electroneurographically recorded (ENG) via bilateral ventral roots following treatment with three different concentrations (25, 100 and 200 pM) of the neurotransmitter, 5-hydroxytryptamine (5-HT), i.e., serotonin, to determine its effects on spinal pattern generation.

A 30-mer oligonucleotide probe encoding the "A box" and anticodon loop regions of a human glycine tRNA gene was used to isolate a 581bp DNA fragment from a bovine genomic DNA library. Although the cross-hybridizing segment of DNA was found not to encode any tRNA gene or pseudogene, a region with homology to the "C-element" of the "BOV-tA" type Alulike artiodactyl retroposons was identified. This cross-hybridization was determined to be the result of conserved RNA polymerase III promoter elements in the probe portion of the tRNA gene and these repetitive elements. A microsatellite repeat (TC) was also found associated with this element. Future screening for bovine tRNA genes will require the use of a) longer probes and higher stringency hybridization conditions or b) the simultaneous screening with probes from the 5' and 3' ends of the gene which avoid the conserved Pol III promoter boxes.

This research evaluated the potential of activation and attachment, as sequential companion biomarkers of phagocytosis by earthworm, Lumbricus terrestris, immunoactive coelomocytes for use in immunotoxicology. The potential was assessed by exposing earthworms to sublethal concentrations of CuSO4 and Arochlor 1254®, chemicals used as reference or standard immunotoxicants.

The proposed biology curriculum for non-majors has one main objective, namely to improve scientific literacy among college students. The National Science Education Standards defines scientific literacy as "the knowledge and understanding of scientific concepts and processes required for personal decision making, participation in civic and cultural affairs, and economic productivity". The suggested strategies to accomplish this goal are to limit the number of topics covered, introduce relevant scientific terminology, emphasize general biological concepts and themes, and hone critical thinking and problem-solving skills. Activities such as group projects, written and oral assignments, and class discussions are effective tools to assess student ability to communicate scientifically. It is also important for students to make connections between the course subject matter and how it affects real life events.

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