Modeling the Mixed-Lineage Leukemia (MLL1) Multi-Protein Complex in Budding Yeast Saccharomyces cerevisiae
The chromosomal rearrangements that can occur within the MLL (mixed lineage leukemia) gene are associated with a variety of leukemias. Though the molecular mechanisms behind the oncogenic activity of MLL chimeric proteins remains obscure, it is known that several MLL complexes exist in humans, including MLL1. The MLL1 methyltransferase enzyme is part of a multi-protein complex that via methylation of histone H3, specifically at lysine 4, regulates gene expression. It is also known that this complex has a homolog in Saccharomyces cerevisiae, the COMPASS complex. We replaced specific proteins in the yeast COMPASS complex with their human counterparts (RbBP5, WDR5, and MLL) to further elucidate their roles in the regulation of the enzymatic activity of the MLL1 complex. We then assayed for the activity of the protein complex by detecting histone H3K4 methylation by Western blotting. Deletion of the SWD3 gene and the SWD1 gene of the COMPASS complex led to the elimination of H3K4me3 in yeast. The human homologues of each gene were then transformed into the deletion yeast strains, but a full rescue of the phenotypes was not observed. This research may lead to a better understanding of the human MLL protein complex and its role in cell regulation and cancer.
Dept of Biology, Furman University, Greenville, SC
The Middle Fork of the Salmon River, Idaho flows 110 miles through the Salmon River Mountains in the midst of the 2.367 million acre (9,580 km2) Frank Church--River of No Return Wilderness Area. The area is one of the least developed in North America, thus the river and surrounding watershed are nearly pristine. This setting was chosen to investigate the contribution of E. coli from native warm-bodied animals to natural riverine systems. In this study, 104 E. coli isolates from sites along the Middle Fork were analyzed by antibiotic resistance analysis to investigate their population structure and possible sources of origin. The correct classification rate was 77.9% for isolates from deer, horse, an unknown carnivore, and a laboratory reference strain 25922. Of the isolates collected from the Middle Fork, 82.1% matched none of the animals tested and represent another source of origin.
Dept of Biological and Environmental Sciences, University of West Alabama, Livingston, AL
160 • Brian S. Burnes
Sources of Escherichia coli In Lake Martin, Alabama
Lake Martin, Alabama is a 44,000-acre (178 km²) hydroelectric reservoir built in 1926. The lake has become highly developed in areas and in summer months is frequented by thousands of recreational boaters and swimmers. Additionally, wild geese nest on the lake, often in proximity to swimming areas. Occasional high E. coli counts from Lake Martin waters have raised the question of whether geese or humans may be responsible, in some part, for the bacterial contamination. In this study, 76 E. coli isolates from various sites in Lake Martin were analyzed by antibiotic resistance analysis to investigate their population structure and possible sources of origin. The correct classification rate was 97.2% for isolates from humans, geese, and a laboratory reference strain 25922. Of the isolates collected from sites in Lake Martin, 82.5% were classified as human in origin.
Dept of Biological and Environmental Sciences, University of West Alabama, Livingston, AL
161 • Andrew J. Jajack, Andrew E. Rosselot, Blake W. Nelson, Jay A. Yoder
Pathogenic Consequences to Honey Bee Colonies From Reducing the Abundance of Beneficial Fungi by Fungicide Spraying
Fungicides used for treating agricultural and orchard crops minimize the amount of naturally occurring spores in the environment. Honey bee (Apismellifera) colonies rely on certain beneficial fungi, Aspergillus, Penicillium, Cladosporium, Rhizopus, to generate a natural defense shield for protection against microbial diseases and to make bee bread, stored fermented pollen, a source of food for proper development of bee larvae. During foraging, fungicide residues are brought into the colony via contaminated pollen. To explore the relationship between fungicide spraying and bee diseases, bee bread samples from seven habitats were analyzed for fungicide residues and fungus composition combined with a bee disease diagnosis. A 70% overall reduction in fungal components, targeting different fungi, was noticed in bee bread from fungicide-sprayed habitats versus control bee bread from unsprayed regions that had no detectable fungicides. Surprisingly, samples from a certified organic orchard displayed the greatest fungicide contamination and reduction in colony-associated fungi. Bee colonies having fungicide contamination had chalkbrood symptoms, a lethal mummification disease of bee larvae. We concluded that fungicide contamination can occur for any bee colony within 3.5km (bee flight range) of a sprayed area; different fungicides impact composition of bee colony-associated fungi differently, thus moving bee colonies has particular detrimental effects; and chalkbrood is a sign of an immuno-compromised colony that has elevated risk of colony collapse disorder.
Dept of Biology, Wittenberg University, Springfield, OH
