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Atrazine is currently the most widely used herbicide in the U.S. Its effects on embryonic development of Xenopus and fathead minnows was analyzed in this study. Embryos were exposed to one of five different exposures: atrazine (0, 20, or 250 μg/L) or ethynyl estradiol (EE2) (1 or 100 μg/L), all containing 0.025% acetone:methanol. Fish and frogs were exposed immediately after fertilization until no later than 180h in development. At all concentrations, atrazine did not significantly affect timing of development, muscle contractions, embryonic length, yolk diameter, or mortality. Atrazine-exposed frogs and fish, however, did exhibit altered morphology. EE2 did not affect timing of development or muscle contractions of frogs and fish. EE2-exposed fish did have larger yolk diameters than the others exposed to atrazine, possibly indicating slower uptake of nutrients from the yolk sac. However, EE2-exposed frogs had no significantly altered timing of development, muscle contractions, embryonic length, mortality, or morphology. There was also no effect of atrazine or EE2 on cartilage development of frogs. Though few effects were seen this early in development, other studies do demonstrate the effects of atrazine later in development.
An investigation of bacterial aerosols emitted from aeration tanks at an activated sludge wastewater treatment plant was conducted by Niagara University undergraduates as a way to explore local microbial issues and their effects on society. Ambient air concentrations of bacteria were measured upwind and downwind of the aeration tanks, and any downwind increase was attributed to the tanks. The results revealed that total bacterial concentrations were significantly greater downwind of the tanks as compared to upwind, and bacterial air pollution was believed to be a result of the aeration process. Among the genera isolated downwind were Serratia, Klebsiella, and Escherichia, all potential pathogens. The project enabled the Niagara University students to perform service learning that highlighted the importance of microbiology and microbiologists at the local community level.
Planaria (Dugesia tigrina) are freshwater flatworms that are frequently studied because of their simple well-defined nervous system. Previous studies concluded that planaria can be trained to favor a direction in a Y- or T-maze using shock or other negative stimuli, but many of these experiments performed few overall runs and/or tested few individuals. The current study examines whether planaria have a directional bias and the ability to learn by using Y-mazes. The pre-conditioning period determined initial directional bias and was used to assign training directions. The conditioning period used electrical shock as a negative stimulus to condition planaria to select a specific turning direction in the Y-maze. Post-conditioning tested whether planaria maintained their learned behavior. Control planaria were not shocked during the conditioning period. Each period consisted of 3 trials with 10 runs in each trial. When examining the results of a single trial, many planaria demonstrated a directional bias. However, if individual trials for each experimental period were examined together, the majority of planaria were non-bias. Experimental planaria showed changes in their directional preferences during the conditioning period, but returned to their original bias, matching the controls, in post-conditioning. Planaria showed evidence of being trainable, but a total of 30 runs over 3 days may not be enough time for retention to occur.
Marin County of California has the highest incidence of suicide in the nation. These high statistics are generally attributed to the Golden Gate Bridge and San Quentin State Prison. Both locations bring additional suicides to the county since people come from other areas to jump off of the Golden Gate Bridge, and prisoners from all over California who are sentenced to death reside in San Quentin. In this study, we did a detailed analysis of the Marin County suicide statistics and determined the impact of the Golden Gate Bridge. Death statistics from Marin County (Holmes, 2005) were analyzed according to manner of death. The suicide categories were further subdivided into method of suicide, age of suicide victims, and gender of suicide victims. Special emphasis was placed on the Golden Gate Bridge as a method of suicide and this study also attempts to map the pattern of residency of the bridge jumpers. Our analysis was focused on data from more recent years (1990 through 2005) and our results show that while self-inflicted gunshot wounds are the leading method of suicide nationally, Golden Gate Bridge jumpers are the leading method of suicide in Marin County.
This study investigated the ability of green, black, and oolong tea to inhibit the growth of Streptococcus mutans in the human mouth. Tea is known to contain various catechins which have been shown to hinder the in vitro growth of bacteria. Streptococcus mutans is a bacterium known to promote the development of dental caries, which is one of the most common bacterial infections in the world. Twenty-two young adults were divided into groups ingesting either green tea, black tea, oolong tea, or hot water for a period of twenty-one days. Saliva samples were taken once weekly throughout the duration of the study and analyzed using Snyder test agar. It was expected that green tea would show the greatest inhibitory effect on the bacteria, followed by oolong and lastly black tea. Final results indicated that while no large difference was found between the different groups, an overall a decline in bacteria levels across the treatments was shown as the study progressed.
Regeneration of anterior and posterior structures following fragmentation is a well-known characteristic of Lumbriculus variegatus, a freshwater oligochaete. Elucidation of cellular activities occurring during regeneration in oligochaetes has relied on classic histological methods. In this project, molecular and chemical approaches were used to analyze the role of cell proliferation and cell migration in L. variegatus regeneration. Mitosis was blocked through incubation of worm fragments in 2.5 mM colchicine or 25 μg/ml vinblastine sulfate. Worm fragments incubated in these drugs no longer regenerated heads or tails. Because colchicine and vinblastine may affect cellular processes other than mitosis, more direct evidence of cell proliferation was obtained by soaking regenerating worms in 5 mM bromodeoxyuridine (BrdU). At various times following BrdU treatment, worms were fixed and macerates of regenerating tissues were prepared. The dispersed cells were stained with antibodies against BrdU followed by incubation with fluorescein-conjugated secondary antibodies. Proliferation of cells, based on BrdU labeling, was observed in both regenerating heads and tails. Incorporation of BrdU into cell nuclei was observed, with extensive labeling detected in cells harvested at 120 hours into regeneration compared to tissues harvested early in the regenerative process (24 to 72 hours). To investigate the potential role of cell migration in the regenerative process, worm fragments were incubated in migration blockers, locostatin (7.5 μM) or latrunculin B (0.15 μM). Both drugs inhibited regeneration of heads and tails. The studies suggested that regeneration in L. variegatus involves both cell migration and cell proliferation and that BrdU labeling can be used to monitor these processes.