afonso-hemoglobingenotype-2009.pdf (406.39 kB)
Hemoglobin genotype has minimal influence on the physiological response of juvenile atlantic cod (Gadus morhua) to environmental challenges
journal contribution
posted on 2009-09-01, 00:00 authored by A Gamperl, C Busby, T Hori, Luis AfonsoLuis Afonso, J HallHemoglobin (Hb) polymorphism in cod is associated with temperature‐related differences in biogeographical distribution, and several authors have suggested that functional characteristics of the various hemoglobin isoforms (HbIs) directly influence phenotypic traits such as growth rate. However, no study has directly examined whether Hb genotype translates into physiological differences at the whole animal level. Thus, we generated a family of juvenile Atlantic cod consisting of all three main Hb genotypes (HbI‐1/1, HbI‐2/2, and HbI‐1/2) by crossing a single pair of heterozygous parents, and we compared their metabolic and cortisol responses to an acute thermal challenge (10°C to their critical thermal maximum [CTM] or 22°C, respectively) and tolerance of graded hypoxia. There were no differences in routine metabolism (at 10°C), maximum metabolic rate, metabolic scope, CTM (overall mean 22.9° ± 0.2°C), or resting and poststress plasma cortisol levels among Hb genotypes. Further, although the HbI‐1/1 fish grew more (by 15%–30% during the first 9 mo) when reared at 10° ± 1°C and had a slightly enhanced hypoxia tolerance at 10°C (e.g., the critical O2 levels for HbI‐1/1, HbI‐2/2, and HbI‐1/2 cod were 35.56% ± 1.24%, and 40.20% ± 1.99% air saturation, respectively), these results are contradictory to expectations based on HbI functional properties. Thus, our findings (1) do not support previous assumptions that growth rate differences among cod Hb genotypes result from a more efficient use of the oxygen supply—that is, reduced standard metabolic rates and/or increased metabolic capacity—and (2) suggest that in juvenile cod, there is no selective advantage to having a particular Hb genotype with regards to the capacity to withstand ecologically relevant environmental challenges.
History
Journal
Physiological and biochemical zoologyVolume
82Issue
5Pagination
483 - 494Publisher
University of Chicago PressLocation
Chicago, Ill.Publisher DOI
ISSN
1522-2152eISSN
1537-5293Language
engPublication classification
C1.1 Refereed article in a scholarly journalCopyright notice
2009, The University of ChicagoUsage metrics
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Keywords
biogeographybloodenvironmental factorgadoidgenotypegrowth ratehemoglobinhypoxiajuvenilephysiological responsepolymorphismScience & TechnologyLife Sciences & BiomedicinePhysiologyZoologyOXYGEN-BINDING-PROPERTIESPREFERRED TEMPERATURESTRESS RESPONSESMARINE FISHESGROWTHL.PERFORMANCEVARIANTSPhysiologyZoology
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