RESEARCH ARTICLE


Ecological Effects on Food Utilization, Trypsin Isozymes, and Performance Qualities of Growth and Maturation in Northeast Arctic Cod (Gadus morhua L.)



Krisna Rungruangsak-Torrissen1, 2, *, Karun Thongprajukaew2, 3, Kanokwan Sansuwan3, Passara Thapthimdaeng3, Uthaiwan Kovitvadhi2, 3, Supaporn Seetaha4, Kiattawee Choowongkomon2, 4, Inger M. Beck5, Ole O. Arnøy
1 Institute of Marine Research, Ecosystem Processes Research Group, Matre Research Station, N-5984 Matredal, Norway;
2 Biochemical Research Unit for Feed Utilization Assessment, Kasetsart University, Bangkok, Thailand


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© 2012 Rungruangsak-Torrissen et al.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: https://creativecommons.org/licenses/by/4.0/legalcode. This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Affiliation: 3 Department of Zoology, Kasetsart University, Bangkok, Thailand
Affiliation: 4 Department of Biochemistry, Faculty of Science, Kasetsart University, Bangkok, Thailand
Affiliation: 5 Institute of Marine Research, Ecosystem Processes Research Group, P.O. Box 1870 Nordnes, Bergen, Norway
* Address correspondence to this author at the Matre Research Station, N-5984 Matredal, Norway; Tel: +47 56367539; E-mail: Krisnart@imr.no


Abstract

The work demonstrates, for the first time, natural biological changes in fish during maturing processes using a unique combination of different biochemical techniques. Northeast Arctic cod caught by demersal trawls were studied in three Barents Sea areas during February–March 2008. Older larger cod from area A (between North Kanin Bank and Eastern Basin) had higher food utilization efficiency (with females showing highest white muscle protein synthesis capacity) than those from areas B (Kanin Bank) and C (Central Bank). Populations in areas A and C living in separate environments showed parallel regressions of pyloric caecal slope T/C ratio, with different elevations of trypsin specific activities and trypsin isozymes expressions. Approximately 30 trypsin isozymes were observed, with 13 isozymes of possibly exogenous trypsin isozyme fragments from prey items found at higher percentage of cod in areas A and B with higher food varieties. Larger maturing cod required higher energy from carbohydrate (probably phytoplankton), as amylase specific activity correlated with body weight. White muscle RNA levels were varied among females from different areas, but not among males. RNA and RNA/protein ratio levels were higher in oocytes than white muscle, and these levels decreased in higher developed oocytes. Oocyte trypsin-like specific activity in areas B < A < C (with oocyte T/C ratio in areas B > A > C) illustrated that females from area B (youngest with lowest oocyte protein turnover) had highest maturation rate, and would reach their spawning area(s) before those from areas A and C. Younger females (probably also males) living closer to coastal area with higher temperature and food varieties would reach sexual maturity faster than older cod and those living far from coastal area.

Keywords: Trypsin/chymotrypsin (T/C) ratio, trypsin isozymes, amylase, RNA, RNA/protein ratio, protein/lipid (P/L) ratio, pyloric caeca, white muscle, oocytes.