Organizational Unit:

School of Biological Sciences

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https://hdl.handle.net/1853/70750

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Organizational Unit

College of Sciences

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Organizational Unit

Center for the Study of Systems Biology

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https://finding-aids.library.gatech.edu/agents/corporate_entities/1131

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Publication Search Results

Now showing 1 - 10 of 15

The Effects of Flow on Swimming Behavior of Brachionus manjavacas (Rotifera)

(Georgia Institute of Technology, 2013-12-11) Rittweger, Shelby

Rotifers serve as model species and are crucial to the zooplankton communities in terms of feeding and nutrition as well as their overall contribution to aquatic food webs (Wallace et al., 2010). Rotifers experience fluid flow in their natural environments of lakes and streams. Fluid velocity acts as stimulus to rotifers, causing them to adjust their swimming speed and direction. I am interested in how rotifers respond to flow, which is known as rheotaxis (Marcos, 2012). Brachionus manjavacas is the rotifer species employed in my experiments. This study simulates fluid flow at rates similar to that rotifers may experience in a riverine ecosystem with unidirectional flow. My intention is to uncover the ways in which the animals respond to flow in these tightly controlled conditions. Rotifers are categorized by age and tested in flow rates ranging from 0.0 to 1.0 mm/sec. Video analysis enables us to quantify swimming velocity and dissect its directionality. The study observes Brachionus manjavacas behavior in terms of aging and analyzes behavior (swimming) from an ecological perspective. It was observed that two-day-old rotifers swim the fastest on average, while four-day-old animals show fastest swimming patterns against the flow. The end result is a behavioral profile that can be useful for understanding how rotifers adapt to flow.
Evolution of Reproduction and Stress Tolerance in Brachionid Rotifers

(Georgia Institute of Technology, 2012-08) Smith, Hilary April

Stress can be a driving force for new evolutionary changes leading to local adaptation, or may be responded to with pre-existing, ancestral tolerance mechanisms. Using brachionid rotifers (microzooplankton) as a study system, I demonstrate roles of both conserved physiological mechanisms (heat shock protein induction) and rapid evolution of traits in response to ecologically relevant stressors such as temperature and hydroperiod. Rapid evolution of higher levels of sex and dormancy in cultures mimicking temporary waters represents an eco-evolutionary dynamic, with trait evolution feeding back into effects on ecology (i.e., reduced population growth). I also reveal that prolonged culture in a benign laboratory environment leads to evolution of increased lifespan and fecundity, perhaps due to reduction of extrinsic mortality factors. Potential mechanisms (e.g., hormonal signals) are suggested that may control evolvability of facets of the stress response. Due to prior studies suggesting a role of progesterone signaling in rotifer sex and dormancy, the membrane associated progesterone receptor is assayed as a candidate gene that could show positive selection indicating rapid divergence. Despite some sequence variation that may contribute to functional differences among species, results indicate this hormone receptor is under purifying selection. Detailed analyses of multiple stress responses and their evolution as performed here will be imperative to understanding current patterns of local adaptation and trait-environment correlations. Such research also is key to predicting persistence of species upon introduction to novel habitats and exposure to new stressors (e.g., warming due to climate change). Perhaps one of the most intriguing results of this dissertation is the rapid, adaptive change in levels of sex and dormancy in a metazoan through new mutations or re-arrangements of the genetic material. This suggests species may be able to rapidly evolve tolerance of new stressors, even if standing genetic variation does not currently encompass the suite of alleles necessary for survival.
Using Microarrays to Quantify Stress Responses in Natural Populations of Coral

(Georgia Institute of Technology, 2007-07-06) Edge, Sara Elizabeth

Coral reefs are one of the world s most valuable ecosystems but are declining at an accelerating rate. Common stressors impacting coral health include elevated temperatures, changes in light intensity, sedimentation, and increased exposure to pollutants. Traditionally, physiological responses have been measured to assess coral health but usually do not identify the stressor or the underlying mechanisms causing a response. In addition, coral may be stressed beyond recovery by the time a physiological response is observed. Changes in gene expression are key elements of the stress response, usually occur before physiological damage is evident, and can be directly related to the causative agent of stress. My research focuses on detecting sublethal responses to stress in Scleractinian coral using genetic biomarkers and gene expression profiling. Through the application of molecular technology, I have developed a coral stress gene microarray to investigate the responses of coral to various stressors. Results from controlled laboratory exposures provide evidence for unique gene expression profiles associated with specific stressors. Results from field studies reveal the feasibility of using array technology to investigate changes in gene expression of natural coral populations across time and between sites. For example, the array has been used to detect stress in coral populations related to seasonal events, such as precipitation as well as point source stress, such as xenobiotics. The temporal and spatial regulation of specific genes within a genome determines the metabolic activity of an organism and can be used to identify changes in cellular responses to various stimuli. These cellular events precede population-level changes and could be useful biomarkers if linked to specific physiological or ecological events. This research is important because it identifies stress at a sub-lethal level and can aid resource managers in decision making by prioritizing the stressors impacting coral reefs.
Assessing coral stress responses at the level of gene expression

(Georgia Institute of Technology, 2001-05) Morgan, Michael Boyce
Molecular ecology of mate recognition in the harpacticoid copepod Tigriopus : antibody production, protein purification, and fitness consequences

(Georgia Institute of Technology, 2001-05) Ting, Joy Holtvluwer
Studies of a mate recognition gene and its product from the rotifer Brachionus plicatilis

(Georgia Institute of Technology, 2000-12) Dingmann, Brian Joseph
Toxicant interactions with the biotic and abiotic environment of freshwater rotifers : implications for ecological risk assessment

(Georgia Institute of Technology, 2000-05) Preston, Benjamin Lee
Chemical communication during mate recognition in the harpacticoid copepod tigriopus japonicus

(Georgia Institute of Technology, 1998-12) Kelly, Lisa S.
Comparative sensitivity of the early life history stages of the Blue Crab, callinectes sapidus, to mercury exposure

(Georgia Institute of Technology, 1998-12) O'Malley, Kristen Marie
Combinations of natural and anthropogenic stressors affect populations of freshwater rotifers

(Georgia Institute of Technology, 1997-12) Cecchine, Gary Anthony, III