Sponsor
Portland State University. Department of Biology
First Advisor
Jason E. Podrabsky
Date of Publication
Fall 1-1-2012
Document Type
Thesis
Degree Name
Master of Science (M.S.) in Biology
Department
Biology
Language
English
Subjects
Killifishes -- Embryos -- Effect of temperature on, Killifishes -- Embryos -- Development, Anoxemia -- Pathophysiology
DOI
10.15760/etd.888
Physical Description
1 online resource (vii, 46 p.) : ill. (some col.)
Abstract
Little is known about the physiology or biochemistry of hypoxia (reduced levels of oxygen) tolerance during development in vertebrate embryos. In most species, relatively brief bouts of severe hypoxia are lethal or teratogenic. An exception to such hypoxia intolerance is the annual killifish Austrofundulus limnaeus, in which populations persist in hypoxic environments. This species inhabits seasonal ponds in Venezuela, surviving through the dry season in the form of diapausing embryos. Embedded in the pond sediment, embryos of A. limnaeus are routinely exposed to hypoxia and anoxia (lack of oxygen) as part of their normal development. Here, we exposed embryos to various levels of PO2 (21.2, 15.6, 10.8, 8.4, 6.1, 3.6, and 2.2 kPa) at two different temperatures (25°C and 30°C) to study the effects on developmental rate and heart rate. We also measured enzyme activity and quantified DNA content of individual embryos to compare differences among the varying levels of hypoxia and temperature. Hypoxia caused a significant decline in developmental rate and caused a stage-specific decline in heart rate. Higher temperature caused an increase in the developmental rate for those embryos incubated at PO2 of 6.1 kPa and greater. Temperature had a negative effect by hindering development below a PO2 of 6.1 kPa. Total embryonic DNA content was reduced at low partial pressures (15.6, 10.8, 8.4, 6.1, 3.6, and 2.2 kPa) of oxygen. Citrate synthase, lactate dehydrogenase, and phosphoenolpyruvate carboxykinase were all down-regulated indicating a complete lack of enzymatic metabolic compensation to combat reduced oxygen levels.
Rights
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Persistent Identifier
http://archives.pdx.edu/ds/psu/8857
Recommended Citation
Anderson, Skye N., "The Effects of Hypoxia and Temperature on Developing Embryos of the Annual Killifish Austrofundulus limnaeus" (2012). Dissertations and Theses. Paper 888.
https://doi.org/10.15760/etd.888
Included in
Aquaculture and Fisheries Commons, Developmental Biology Commons, Other Physiology Commons