https://doi.org/10.33697/ajur.2008.012
https://doi.org/10.33697/ajur.2008.013
Author(s):
C. C. Chancey
Affiliation:
American Journal of Undergraduate Research, University of Northern Iowa, Cedar Falls, Iowa 50614-0150 USA
https://doi.org/10.33697/ajur.2008.014
Author(s):
Rebecca M. Cripps and George W. Kipphut
Affiliation:
Department of Biological Sciences & Hancock Biological Station, Murray State University, Murray, Kentucky 42071 USA
ABSTRACT:
Previous research has shown stable isotope ratios of nitrogen in fish and other animals may vary depending on their food source. Ecologists have had some success in determining feeding and trophic relationships within an ecosystem using stable isotopic ratios. In this study, nitrogen stable isotopic ratios were measured in populations of Lepomis macrochirus (Blue Gill) in Kentucky Lake Reservoir and in a small tributary, Ledbetter Creek, in western Kentucky. The nitrogen isotopic ratios between these populations were statistically different. Even though fish are able to migrate freely between the two environments, the isotopic results suggest that the Lepomis macrochirus in Ledbetter Creek were spending enough time feeding in that environment to alter their isotopic signature. These results may lead to a better understanding of how Lepomis macrochirus utilize both stream and reservoir environments.
Comparison of Biochemical and Chemical Digestion and Detection Methods for Carbohydrates
https://doi.org/10.33697/ajur.2008.015
Author(s):
Katie Miloski, Kelly Wallace, Ashley Fenger, Ellen Schneider, Kestas Bendinskas
Affiliation:
Department of Chemistry, State University of New York—Oswego, Oswego, New York 13126 USA
ABSTRACT:
There is a multitude of chemical and biochemical detection methods for sugars. Which ones would be most practical in an undergraduate laboratory setting? How to best detect non-reducing disaccharides? How to make such lab fun for students to perform? After trying several spectrophotometric methods, it was found that chemical detection by dinitrosalicylic acid and biochemical detection by hexokinase/glucose-6-phosphate dehydrogenase reagent are most appropriate. Sucrose, a non-reducing disaccharide was digested chemically with hydrochloric acid and biochemically with invertase. It was concluded that chemical detection and biochemical detection compliment each other. Chemical digestion method was preferred over the digestion by invertase. These methods were applied for testing the validity of sugar ingredients printed on drink labels as well as the measurement of sugar levels in ripening bananas at two different conditions. The comprehensive comparison of these methods and the detection of sugar concentrations in interesting samples might serve as a basis for an undergraduate chemistry laboratory.
The Effects Hypergravity on the Morphology of Xenopus Embryos
https://doi.org/10.33697/ajur.2008.016
Author(s):
Rochelle Remus and Darrell Wiens
Affiliation:
Department of Biology, University of Northern Iowa, Cedar Falls, Iowa 50614-0421 USA
ABSTRACT:
Early amphibian development is sensitive to both reduced and elevated gravitational force. But later, following gastrulation and neurulation, a critical population of cells must migrate from the dorsal neural tube outward to destinations throughout the body where they differentiate into a wide variety of critical tissues including head cartilage. These cells, the neural crest cells, respond to extracellular cues and signals that guide migration and differentiation in an intricate process that may also be sensitive to altered gravity. We examined the effects of hypergravity on the migration of neural crest cells to form head skeleton cartilage, and on body size in Xenopus embryos. To investigate this we centrifuged embryos at 7G or 10G, from yolk plug stage (gastrulation) through five days of development to stage 45 when feeding begins. A control group was placed on the centrifuge. After centrifugation, the embryos were fixed, cleared and stained with Alcian Blue to reveal cartilage. We then captured images for analysis to obtain body and head cartilage measurements. We found that hypergravity retarded the growth of Xenopus embryos, possibly via increased load on the cardiovascular system. Surprisingly, it also resulted in significantly larger and more asymmetrical head cartilages, when corrected for body size, but it did not result in a significantly higher frequency of malformations. Our results support the likelihood that hypergravity inhibits body growth and perturbs the formation of neural crest derived head cartilage.