Page Banner

United States Department of Agriculture

Agricultural Research Service

Research Project: Genetics, Physiology, and Health Research to Improve Catfish Production

Location: Warmwater Aquaculture Research Unit

Title: Expression of leptin-like mRNA in channel catfish (Ictalurus punctatus) is induced by exposure to Edwardsiella ictaluri but is independent of energy status

Authors
item Kobayashi, Yashiro -
item Quiniou, Sylvie
item Booth, Natha
item Peterson, Brian

Submitted to: General and Comparative Endocrinology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 5, 2011
Publication Date: April 15, 2011
Citation: Kobayashi, Y., Quiniou, S., Booth, N.J., Peterson, B.C. 2011. Expression of leptin-like mRNA in channel catfish (Ictalurus punctatus) is induced by exposure to Edwardsiella ictaluri but is independent of energy status. General and Comparative Endocrinology. 173:411-418.

Interpretive Summary: Leptin is involved in regulation of food intake and energy maintenance in mammals. In channel catfish, a messenger RNA that encodes a leptin-like peptide (LLP) was discovered. The objectives of our studies were to characterize tissue expression of LLP mRNA and changes in its expression after prolonged fasting and exposure to Edwardsiella ictaluri, (E. ictaluri), the bacteria that causes enteric septicemia in catfish. Channel catfish LLP shared very low sequence similarities with leptin of other fish species or the mammalian leptin (24-49 %). LLP mRNA expression was detected in various tissues including brain, stomach, spleen, heart, liver, and trunk kidney but was especially high in liver and trunk kidney. Expression of LLP mRNA in liver and brain was unaffected by prolonged fasting. Liver expression of LLP mRNA was elevated 2 days after fish were exposed to E. ictaluri. In comparison, expression of LLP mRNA in trunk kidney and spleen was elevated 1 day after E. ictaluri exposure. Based on our results, the catfish LLP does not seem to be involved in the regulation of food intake or energy maintenance. Our results suggest catfish LLP may be involved in the immune response of catfish challenged with disease.

Technical Abstract: Leptin is a key pleiotropic cytokine involved in regulation of food intake and energy homeostasis in mammals. In channel catfish, the presence of a messenger RNA that encodes a leptin-like peptide (LLP) has been described. The objectives of our studies were to characterize tissue expression of LLP mRNA and changes in its expression after prolonged fasting and exposure to Edwardsiella ictaluri, (E. ictaluri), the bacteria that causes enteric septicemia in catfish. Channel catfish LLP gene was sequenced by genome walking and by 5’- and 3’-RACE. Channel catfish LLP gene contained 3 exons with the coding region located in exons 2 and 3. Nucleotide and putative amino acid sequence of the channel catfish LLP shared very low sequence similarities with leptin of other fish species or the mammalian leptin (24-49 %). The LLP mRNA expression was detected in various tissues including brain, stomach, spleen, heart, liver, and trunk kidney but was especially high in liver and trunk kidney. Expression of LLP mRNA in liver and brain was unaffected (P > 0.1) by prolonged fasting. Hepatic expression of LLP mRNA was elevated (P < 0.05) 2d after fish were exposed to E. ictaluri. In comparison, expression of LLP mRNA in trunk kidney and spleen was elevated (P < 0.05) 1d after E. ictaluri exposure. Furthermore, expression of LLP mRNA in trunk kidney was elevated (P < 0.05) 2d post exposure to E. ictaluri. Based on our results, the catfish LLP does not seem to assume mammalian leptin functions. Further investigations are required to clearly define the identity and functions of this transcript.

Last Modified: 10/23/2014
Footer Content Back to Top of Page