Year

2014

Season

Spring

Paper Type

Master's Thesis

College

College of Arts and Sciences

Degree Name

Master of Science in Biology (MS)

Department

Biology

NACO controlled Corporate Body

University of North Florida. Department of Biology

First Advisor

Dr. Gregory A. Ahearn

Second Advisor

Dr. Amy L. Lane

Third Advisor

Dr. Julie P. Richmond

Department Chair

Dr. Daniel Moon

College Dean

Dr. Barbara Hetrick

Abstract

Previous nutritional physiology research using L-histidine and zinc in American lobster intestine (Homarus americanus) has suggested that these solutes can be co-transported as complexes (Histidine-Zinc-Histidine) across the intestine using a peptide transporter. Furthermore, transport of L-leucine was shown to be inhibited by high calcium concentrations. Dipeptide and bis-complex transport and the role of calcium were investigated in the perfused intestines of lobster and Atlantic white shrimp (Litopenaeus setiferus). Following trans-intestinal transport, serosal medium was analyzed for amino acid composition by gas chromatography. In lobster, the transport of glycylsarcosine (Gly-Sar) from mucosa to serosa was stimulated two-fold with luminal pH 8.5, compared to the pH 5.5 control. Mucosa to serosa and serosa to mucosa fluxes of Gly-Sar were measured; the dipeptide was transported intact in both directions, but the net flux was from mucosa to serosa. The use of 0.5mM calcium chloride stimulated Gly-Sar transport two-fold, compared to 25 mM. In shrimp, the addition of 50 µM zinc chloride increased the rate of L-histidine transport, while Gly-Sar inhibited histidine transport in the presence of zinc. The rate of histidine transport was significantly higher with 1mM calcium chloride than with 25mM. These results suggest that shrimp transport bis-complexes in a manner similar to lobster. High calcium concentration had an inhibitory effect on both amino acid and dipeptide transport. Proposed mechanisms accounting for the effects of metals and calcium on trans-intestinal transports of both amino acids and dipeptides by lobster and shrimp digestive tracts are discussed.

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