Document Detail

Nonhepatic origin of notothenioid antifreeze reveals pancreatic synthesis as common mechanism in polar fish freezing avoidance.
MedLine Citation:
PMID:  16798878     Owner:  NLM     Status:  MEDLINE    
Phylogenetically diverse polar and subpolar marine teleost fishes have evolved antifreeze proteins (AFPs) or antifreeze glycoproteins (AFGPs) to avoid inoculative freezing by internalized ice. For over three decades since the first fish antifreeze (AF) protein was discovered, many studies of teleost freezing avoidance showed hepatic AF synthesis and distribution within the circulation as pivotal in preventing the blood, and therefore the fish, from freezing. We have uncovered an important twist to this long-held paradigm: the complete absence of liver synthesis of AFGPs in any life stage of the Antarctic notothenioids, indicating that the liver plays no role in the freezing avoidance in these fishes. Instead, we found the exocrine pancreas to be the major site of AFGP synthesis and secretion in all life stages, and that pancreatic AFGPs enter the intestinal lumen via the pancreatic duct to prevent ingested ice from nucleating the hyposmotic intestinal fluids. AFGPs appear to remain undegraded in the intestinal milieu, and the composition and relative abundance of intestinal AFGP isoforms are nearly identical to serum AFGPs. Thus, the reabsorption of intact pancreas-derived intestinal AFGPs, and not the liver, is the likely source of circulatory AFGPs in notothenioid fishes. We examined diverse northern fish taxa and Antarctic eelpouts with hepatic synthesis of bloodborne AF and found that they also express secreted pancreatic AF of their respective types. The evolutionary convergence of this functional physiology underscores the hitherto largely unrecognized importance of intestinal freezing prevention in polar teleost freezing avoidance, especially in the chronically icy Antarctic waters.
Chi-Hing C Cheng; Paul A Cziko; Clive W Evans
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.     Date:  2006-06-23
Journal Detail:
Title:  Proceedings of the National Academy of Sciences of the United States of America     Volume:  103     ISSN:  0027-8424     ISO Abbreviation:  Proc. Natl. Acad. Sci. U.S.A.     Publication Date:  2006 Jul 
Date Detail:
Created Date:  2006-07-06     Completed Date:  2006-08-16     Revised Date:  2013-06-07    
Medline Journal Info:
Nlm Unique ID:  7505876     Medline TA:  Proc Natl Acad Sci U S A     Country:  United States    
Other Details:
Languages:  eng     Pagination:  10491-6     Citation Subset:  IM    
Department of Animal Biology, University of Illinois, Urbana, IL 61801, USA.
Data Bank Information
Bank Name/Acc. No.:
GENBANK/DQ062435;  DQ062436;  DQ062437;  DQ062438;  DQ062439;  DQ062440;  DQ062441;  DQ062442;  DQ062443;  DQ062444;  DQ062445;  DQ062446;  DQ062447;  DQ062448;  DQ062449;  DQ062450;  DQ062451;  DQ062452;  DQ062453;  DQ062454;  DQ062455;  DQ062456;  DQ062457;  DQ062458;  DQ062459;  DQ394083
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MeSH Terms
Antarctic Regions
Antifreeze Proteins / biosynthesis*,  genetics
Cold Climate*
Fishes / anatomy & histology*,  genetics,  metabolism*
Gastrointestinal Tract / metabolism
Glycoproteins / biosynthesis*,  genetics
Larva / metabolism
Liver / metabolism
Molecular Sequence Data
Organ Specificity
Osmotic Pressure
Pancreas / metabolism*
Reg. No./Substance:
0/Antifreeze Proteins; 0/Glycoproteins

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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