Session 1B
Molecular and Feeding Dynamics in Ecosystems
1:00 PM to 2:30 PM | Moderated by Vincent Gallucci
- Presenter
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- Sarah Kathryn (Sarah) Hu, Junior, Aquatic & Fishery Sciences
- Mentor
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- John Horne,
- Session
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- 1:00 PM to 2:30 PM
The deprivation of necessary oxygen in aquatic environments, called hypoxia, may affect aquatic environments by influencing predator-prey interactions. Seasonal hypoxia in the form of low dissolved oxygen (DO) layers affect fish and zooplankton vertical migrations. Lower Hood Canal, located in Washington State, is vulnerable to hypoxia because of low water circulation and large anthropogenic inputs of phosphorous and nitrogen in runoff water. Low water circulation and high nutrient input, causes an increased abundance of marine organisms that use the oxygen, which depletes DO and can lead to fish deaths. The objective of this study was to evaluate the influence of hypoxia on Pacific herring (Clupea pallasii) zooplankton consumption. Time of year and geographic region within Hood Canal were used as variables to compare consumption at varying DO levels. Herring were sampled in July, September, and December. In December, samples were also collected in two regions that had different DO levels. Higher consumption rates were observed in July and September. Warmer months correspond with pre-hypoxic July and September’s hypoxic peak, while December is considered post-hypoxic. Selectivity of prey, such as larval crab, polycheates, and copepods, reflected seasonal abundance and availability of prey within the environment. Differences in prey consumption may also be attributed to variations of DO content in different regions of Lower Hood Canal. The study demonstrates the link between herring consumption of zooplankton and seasonal conditions.
- Presenter
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- Jessica Ja-Jei (Jessica) Jang, Senior, Aquatic & Fishery Sciences
- Mentors
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- Vincent Gallucci,
- Ian Taylor,
- Session
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- 1:00 PM to 2:30 PM
Dogfish sharks were heavily exploited for their livers in the late 1930s and during WW II. The Puget Sound Fishery was a major contributor of livers for from which Vitamin A was extracted. The high demands for dogfish livers decimated the population in Puget Sound. Since the fisheries were selective (especially for larger sized females), many older age classes were depleted. Data from the Puget Sound Fishery from the 1940s are analyzed using parametric and nonparametric tests to confirm observations in Kelshaw Bonham's Biological Report (1949) about male and female physiological differences. ANOVA analysis is carried out to confirm relationships between the size of animal, the darkness of the liver, the quantity of oil and Vitamin A present in males and females. Although the technique of synthesizing Vitamin A reduced the fishing pressure on the dogfish in the late1950s, the fish is exploited in other parts of the world for their fins, cartilage, liver oil, hides, and as an important traditional use in European countries.
- Presenter
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- Nathan Charles (Nate) Layman, Senior, Biology (General), Environmental Studies
- Mentor
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- Shannon O'Brien,
- Session
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- 1:00 PM to 2:30 PM
Predicting the impacts of climate change on extant species is an important but challenging task. Valuable clues can be obtained by investigating demographic patterns caused by past climatic changes, most notably during and after the last glaciation period. This information can then help identify barriers to migration and divergence, pinpoint evolutionarily significant lineages, and target conservation efforts to particularly vulnerable populations. The elasmobranchs are of particular interest because of their role as top predators, their slow life history and ubiquity in the world’s oceans. Here we investigate the population history of a small shark, the spiny dogfish (Squalus acanthias), as a model elasmobranch because of its large population size and worldwide distribution. Earlier genetic work has already identified two major clades, one in the North Pacific and one in the South Pacific and Atlantic. Here we compare the demographic history of spiny dogfish between the Pacific and Atlantic clades and among major basins within the Atlantic in order to examine the evolutionary history of the species following the last ice age. To this end, dogfish samples were obtained from a variety of locations across the geographical range of the species and sequenced at two separate mitochondrial (mtDNA) markers. We hope to use the resultant data to better understand how climate change may affect population abundance and genetic diversity in the future.
- Presenter
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- Nicole Elizabeth (Nicole) Scharping, Junior, Biology (Molecular, Cellular & Developmental)
- Mentors
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- John Hansen,
- Lucia Vojtech,
- Session
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- 1:00 PM to 2:30 PM
In vertebrate innate immunity, the inflammasome detects pathogenic invaders and initiates the host’s inflammatory response to fight infection. The inflammasome forms when intracellular pathogen detectors called Nod-like receptors (NLRs) sense the presence of pathogens and oligomerize. The oligomer recruits and activates cleaving enzymes called inflammatory caspases, which in turn activate immune system signaling molecules called cytokines. These cytokines are secreted from the infected cell, initiating local inflammation. Our group is using zebrafish to study the evolutionary conservation of the inflammasome, as zebrafish have an expanded NLR gene family in comparison to mammals. Based upon the properties of conserved protein domains within zebrafish NLRs, we hypothesized that there are NLRs that either activate or inhibit inflammation, thus expressing a dual regulatory role in innate immunity. To test this hypothesis, we developed a yeast-2-hybrid assay to find protein interactions between “bait” plasmid constructs made from a known NLR-interacting protein and a “prey” library derived from zebrafish intestinal cDNA. Our screen yielded several potential interacting proteins using the yeast-2-hybrid approach, and these proteins are currently being tested through additional biochemical assays to rule out false interactions. Teleost fish and mammals last shared a common ancestor over 350 million years ago; therefore, using this comparative approach will help us to understand the evolution of inflammation in vertebrates.
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