High-resolution melting analysis of common and recombinant genotypes of the Atlantic cod ( Gadus morhua ) hemoglobin β1 gene in transatlantic populations (original) (raw)
Related papers
Atlantic cod (Gadus morhua) hemoglobin genes: multiplicity and polymorphism
BMC Genetics, 2009
Background: Hemoglobin (Hb) polymorphism, assessed by protein gel electrophoresis, has been used almost exclusively to characterize the genetic structure of Atlantic cod (Gadus morhua) populations and to establish correlations with phenotypic traits such as Hb oxygen binding capacity, temperature tolerance and growth characteristics. The genetic system used to explain the results of gel electrophoresis entails the presence of one polymorphic locus with two major alleles (HbI-1; HbI-2). However, vertebrates have more than one gene encoding Hbs and recent studies have reported that more than one Hb gene is present in Atlantic cod. These observations prompted us to re-evaluate the number of Hb genes expressed in Atlantic cod, and to perform an in depth search for polymorphisms that might produce relevant phenotypes for breeding programs.
Physiological and …, 2009
Hemoglobin (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 (10ЊC to their critical thermal maximum [CTM] or 22ЊC, respectively) and tolerance of graded hypoxia. There were no differences in routine metabolism (at 10ЊC), maximum metabolic rate, metabolic scope, CTM (overall mean 22.9Њ ע), or resting and poststress plasma cortisol levels among 0.2ЊC Hb genotypes. Further, although the HbI-1/1 fish grew more (by 15%-30% during the first 9 mo) when reared at 10Њ ע and had a slightly enhanced hypoxia tolerance at 10ЊC (e.g., 1ЊC the critical O 2 levels for HbI-1/1, HbI-2/2, and HbI-1/2 cod were , , and 35.56% ע 1.24% 40.56% ע 1.99% 40.20% ע air saturation, respectively), these results are contradic-1.19% tory 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 capacityand (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.
The demography of a haemoglobin polymorphism in the Atlantic cod, Gadus morhua L
Journal of Fish Biology, 2006
Genetic stability was investigated at a polymorphic haemoglobin gene-locus in 13 124 Atlantic cod, Gadus morhua L. A total of 30 year-classes, sampled over 18 years, were variously sampled in 33 named localities. Regional populations showed distinctive allele frequencies, and each major cod fishery showed some degree of genetic imbalance, which was expressed as excessive numbers of homozygotes. This imbalance occurred seasonally in a proportion of the population samples in each of the major cod fisheries. The findings are attributable to migrations of distinctive genetic populations.
New haemoglobin genotypes in Atlantic cod, Gadus morhua: Possible relation with growth
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 2007
In a preliminary study, 121 individually tagged juvenile Atlantic cod (Gadus morhua) were classified according to their haemoglobin genotypes into four groups, i.e., two main haemoglobin genotypes [Hb-I(1/2), Hb-I(2/2)] and two sub-types [Hb-I(1/2b), Hb-I(2/2b)], and reared for 3 months at 10°C, 13°C and T-step (fish reared at 16°C and then subsequently moved to 13 and later to 10°C). Overall growth rates across temperatures were 10% and 19% higher in the Hb-I(2/2b), Hb-I(1/2b) sub-types compared to corresponding Hb-I(2/2) and Hb-I(1/2) main types, respectively. Individual growth rate trajectories varied between the genotypes at all temperatures studied. Our study indicates that under certain environmental conditions higher growth in the two sub-types compared to the main genotypes could be expected. This may indicate difference in other physiological characters not studied here, but seen in previous studies, i.e., oxygen affinity and competitive performance.
Haemoglobin polymorphisms affect the oxygen-binding properties in Atlantic cod populations
Proceedings of the Royal Society B: Biological Sciences, 2009
A major challenge in evolutionary biology is to identify the genes underlying adaptation. The oxygentransporting haemoglobins directly link external conditions with metabolic needs and therefore represent a unique system for studying environmental effects on molecular evolution. We have discovered two haemoglobin polymorphisms in Atlantic cod populations inhabiting varying temperature and oxygen regimes in the North Atlantic. Three-dimensional modelling of the tetrameric haemoglobin structure demonstrated that the two amino acid replacements Met55b 1 Val and Lys62b 1 Ala are located at crucial positions of the a 1 b 1 subunit interface and haem pocket, respectively. The replacements are proposed to affect the oxygen-binding properties by modifying the haemoglobin quaternary structure and electrostatic feature. Intriguingly, the same molecular mechanism for facilitating oxygen binding is found in avian species adapted to high altitudes, illustrating convergent evolution in water-and air-breathing vertebrates to reduction in environmental oxygen availability. Cod populations inhabiting the cold Arctic waters and the low-oxygen Baltic Sea seem well adapted to these conditions by possessing the high oxygen affinity Val55-Ala62 haplotype, while the temperature-insensitive Met55-Lys62 haplotype predominates in the southern populations. The distinct distributions of the functionally different haemoglobin variants indicate that the present biogeography of this ecologically and economically important species might be seriously affected by global warming.
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 2013
Haemoglobin polymorphism in cod (Gadus morhua L) has been investigated throughout the last 50 years. Field studies have shed light on the geographic distribution of the two common alleles (HbI 1 and HbI 2 ), and laboratory studies have shown effects of genotype on physiological traits such as growth, reproduction and hypoxia tolerance. The geographic distribution of alleles shows a correlation with temperature, with increasing frequency of HbI 1 in warmer areas. This is likely due to temperature-related differences in oxygen affinity of the three genotypes. We provide a general ecological introduction to cod haemoglobin polymorphism and a detailed discussion of physiological studies, particularly laboratory growth studies. Although differences in oxygen uptake are almost certainly a contributory mechanism to observed differences in traits such as growth rate, many other environmental, behavioural and social factors may also contribute, making it difficult to quantify the effect of HbI either experimentally or in the field.
Variations in growth in haemoglobin genotypes of Atlantic cod
Fish Physiology and Biochemistry, 2004
In the present paper are described the growth properties of three different haemoglobin genotypes of juvenile Atlantic cod (Gadus morhua) reared at 7, 10, 13 and 16°C. In addition one group was reared under ''temperature steps'' i.e. moved successively from 16 to 13 and 10°C. The genotype Hb-I(2/2) displayed the overall highest growth rate in the temperature range 13-16°C, whereas the Hb-I(1/1) genotype showed the highest overall growth at the lowest temperature (7°C). Accordingly, we found a significant interaction between genotype and temperature. The differences in growth were largest when cod were reared under the temperature step regime where the Hb-I(2/2) genotype displayed 17 and 24% higher growth than Hb-I(1/1) and Hb-I(1/2), respectively. Optimal temperature for growth (T opt. G) varied between the genotypes with the genotype Hb-I(1/2) displaying the highest (mean ± SE) T opt. G (14.5 ± 1:0.8°C) and Hb-I(1/1) the lowest (12.5 ± 0.2°C). The biological significance of this link between biochemical genetic variation and physiological properties might be the influences on growth pattern, ultimate size and age at first maturity.
BMC Research Notes, 2010
Background: Haemoglobin (Hb) and pantophysin (Pan I) markers have been used intensively in population studies of Atlantic cod (Gadus morhua) and in the analysis of traits such as temperature tolerance, growth characteristics and sexual maturation. We used an Illumina GoldenGate panel and the KASPar SNP genotyping system to analyse SNPs in three Atlantic cod families, one of which was polymorphic at the Hb β1 locus, and to generate a genetic linkage map integrating Pan I and multiple Hb loci. Findings: Data generated allowed the mapping of nine Hb loci, the Pan I locus, and other 122 SNPs onto an existing linkage genetic map for Atlantic cod. Four Hb genes (i.e. α1, α4, β1 and β5) have been mapped on linkage group (LG) 2 while the other five (i.e. α2, α3, β2, β3 and β4) were placed on LG18. Pan I was mapped on LG 1 using a newly developed KASPar assay for a SNP variable only in Pan I A allelic variants. The new linkage genetic map presented here comprises 1046 SNPs distributed between 23 linkage groups, with a length of 1145.6 cM. A map produced by forcing additional loci, resulting in a reduced goodness-of-fit for mapped markers, allowed the mapping of a total of 1300 SNPs. Finally, we compared our genetic linkage map data with the genetic linkage map data produced by a different group and identified 29 shared SNPs distributed on 10 different linkage groups.
Journal of Fish Biology, 1999
Significant differences were found at the synaptophysin (Syp I) locus between two groups of Icelandic cod Gadus morhua; Loftstaðahraun (spawning ground), Reykjanesgrunn and Eyrabakkabugur (feeding grounds) on the one hand and Kantur (spawning ground) and Austfjarðadjú p (feeding ground) on the other. There was also a considerable genetic heterogeneity within the former group. The results indicate that the cod in south and south-east Icelandic waters do not belong to one panmictic population. 1999 The Fisheries Society of the British Isles