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Aquatic Vegetation Nutrient Budgets and Sedimentation in a Southwestern Reservoir
During four growing seasons, aquatic vascular plant production and distribution were studied in Pat Mayse Lake, Texas, a 2425 hectare oligo-mesotrophic reservoir. The dominant macrophyte population was Myriophyllum spicatum L. Growth rates and regrowth rates of mechanically harvested Myriophyllum beds were found to be dissimilar. Based on estimates of watermilfoil nutrient content, there were insufficient nutrients in the entire population to alter the trophic status of this reservoir should all of the nutrients be instantaneously released. Sediments were the primary nutrient (nitrogen and phosphorus) sink. Bank erosion and solids transport from the watershed appear to contribute most of the sediments and a lake-wide mean sedimentation rate of 2.5 cm/year was estimated from sediment trap and core sample data.
Gene Dosage Study on Human Chromosome 22
A gene dosage study was conducted on a rare complete trisomy 22 human fibroblast cell line utilizing three lysosomal enzymes, ∝-iduronidase, ∝-galactosidase B, and arylsulfatase A, whose genes are located on chromosome 22 and two control enzymes, ,β-hexosaminidase A and -- fucosidase, with genes not on chromosome 22. A gene dosage effect was clearly demonstrated for an early passage number of the fibroblasts; however, later passage numbers gave inconclusive results. This study suggests that gene dosage studies must be carefully designed to be conducted only on early, matched passage number cells. ∝-fucosidase gave anomalous results most likely due to pleiotropic effects. The present gene dosage study confirmed the trisomic nature of the cell line studied and suggests that this type of study may be a useful diagnostic tool for small deletions, additions, or unbalanced translocations.