http://hdl.handle.net/1974/288 2013-05-25T04:42:26Z 2013-05-25T04:42:26Z Suffel, Jordan http://hdl.handle.net/1974/8020 2013-05-03T14:21:54Z 2013-05-03T04:00:00Z

Title: Cladocerans Remains as Indicators of Environmental Change in an Adirondack “Heritage Lake” Authors: Suffel, Jordan Abstract: Many regions of North America and elsewhere have reported post-1980 declines in lakewater Ca concentrations. Though the biogeochemical dynamics which account for Ca depletion have been recognized, the effects of decreasing Ca concentrations on aquatic ecosystems are less understood. This study used paleolimnological techniques to reconstruct cladoceran assemblages over the past 600-800 years in a minimally disturbed “heritage” lake in the Adirondacks. Knowledge of cladoceran assemblage composition and background variation is necessary so that recent changes can be put into a larger perspective, yet no previous studies have investigated the pre-industrial variation over periods of longer than 100 years. Relative abundance and concentration data suggest that the cladoceran assemblage in Wolf Lake has been relatively stable over the last 600-800 years. Daphnia species in this lake did not respond to calcium declines as predicted, suggesting that the assemblage in Wolf Lake comprise of species which are less sensitive to calcium concentrations or that the current calcium concentrations in the lake have remained stable over the studied time frame. Bosmina size measurement data reinforces the assumption that fish predation in the lake has remained consistent over the studies time frame. Recent increases in Bosmina carapace and mucro length suggest that invertebrate pressures may have increased. Further studies examining the cladoceran assemblage at higher counting and taxonomic resolutions, as well as the investigation of multiple paleoindicator assemblages over the same time frame, will help to assess past environmental conditions at a finer scale and determine the extent of environmental change in this minimally disturbed aquatic community

2013-05-03T04:00:00Z Jahagirdar, Ishanee http://hdl.handle.net/1974/7976 2013-04-29T16:02:23Z 2013-04-29T04:00:00Z

Title: The effect of silver nanoparticles on stress response and gut microbial composition in Drosophila melanogaster larvae Authors: Jahagirdar, Ishanee Abstract: Silver nanoparticles (Ag NPs) have been shown to be highly toxic to certain organisms and can induce stress in cells. The purpose of this study is twofold: first, to examine the stress response to Ag NP exposure on Drosophila melanogaster (fruit fly) larvae, and secondly, to determine if exposure to Ag NPs alters the larval intestinal flora. To answer these questions, D. melanogaster were grown on food mixed with Ag NPs. Ag NP-treated larvae did not appear to differ in their ability to climb to find pupation sites or escape from heat stress. Larval wandering behaviour was examined by devising a test to determine if they could move towards a drop of food. Here, there appeared to be differences in their crawling efficiency, with the Ag NP-treated larvae having shorter path lengths. In order to determine the composition of flora in the digestive tract, DNA was isolated from dissected larval midguts, purified, and then the 16S rRNA genes were amplified. After commercial pyrosequencing and identification by database comparisons, bacterial compositions were obtained showing that the midgut flora does seem to change after treatment with Ag NPs. It is hoped that this research will help elucidate our understanding of the impact NPs have on organisms, which is highly relevant because of the high prevalence of NPs in consumer materials.

2013-04-29T04:00:00Z Lovett, Erica http://hdl.handle.net/1974/7974 2013-04-29T13:12:50Z 2013-04-29T04:00:00Z

Title: Quantifying Clock allele length variation in the wide-ranging rufous-collared sparrow (Zonotrichia capensis) Authors: Lovett, Erica Abstract: The circadian clock is one of the best characterized examples of molecular control of behavior, and utilizes input entrained by photoperiod cues. Through endogenous control, this biochemical mechanism regulates behavioral and physiological rhythms and is governed by the Clock gene. Orthologues of the Clock gene have been observed in a diverse range of organisms; however considerable variation exists in the poly-Q (polyglutamine) repeat region of the gene. Evidence suggests this region may be responsible for observed variance in circadian oscillations, but investigations into the function of the Clock gene in avian species have rendered contrasting results. The broad geographical span and phenotypic variability of the small passerine, the rufous-collared sparrow (Zonotrichia capensis), provide an excellent opportunity to study inter-population variation in the avian Clock gene. In this study, 59 individuals from 17 populations spanning 6,400 km of latitude and 5,000 m of altitude were screened at the Clock gene locus. Four different Clock allele lengths were identified, with one allele comprising 84% of all alleles sampled. No associations between Clock allele length and altitude or longitude between populations were detected, and no evidence of a latitudinal cline in allele length was found. The results suggest that Clock may not influence geographical variation in migratory behavior, or that other genes associated with circadian rhythms modulate Clock expression in this polytypic songbird. Further research should be conducted before any generalizations about the functional significance of the avian Clock gene are made.

2013-04-29T04:00:00Z Kim, Soo-Min http://hdl.handle.net/1974/7973 2013-04-29T13:06:47Z 2013-04-29T04:00:00Z

Title: Interaction of stress response kinase Ssp1 with 14-3-3 proteins Rad24 and Rad25 in response to osmotic stress in Schizosaccharomyces pombe Authors: Kim, Soo-Min Abstract: Cells must tolerate various environmental stressors in order to survive. Ssp1, a protein kinase found in Schizosaccharomyces pombe, is one protein that is responsible for many stress related cellular functions in the cell. Stress response kinase Ssp1 is a calcium/calmodulin dependent protein kinase kinase (CaMKK) homolog. Ssp1 plays a role in actin depolymerization, regulates cell cycle progression, mediates energy producing pathways, and initiates a response to osmotic stress especially at high temperatures (Matsusaka et al. 1995; Valbuena et al. 2011; Rupes et al. 1999). Interestingly, the Ssp1 pathway functions independently from other stress response pathways. In S. pombe two isoforms of 14-3-3 proteins, Rad24 and Rad25, are known to interact with Ssp1. Dissociation of Rad24 from Ssp1 is believed to cause some of the kinase’s transient localization from the cytoplasm to the cell membrane (Freitag et al. unpublished data). This study aims to explore how subpopulations of Ssp1 are controlled with the hopes of discovering other proteins that interact with Ssp1 after hyperosmotic stress. The time course experiment using Ssp1-GFP concluded that pools of Ssp1 function as semi-independent populations. In addition, Nickel-Nitrilotriacetic Acid affinity columns were used in an attempt to differentiate the subpopulation associating with His-tagged Rad24 and Rad25. Future directions include purifying complexes specific to Rad24 and Rad25 in order to see if there are defining proteins that differentiate the two subpopulations. This study has the potential to provide additional information about the Ssp1 pathway and help form the basis for future studies.

2013-04-29T04:00:00Z