| 1. |
- Aaltonen, Kristina, et al.
(författare)
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Unequal segregation of SRK alleles at the S locus in Brassica cretica.
- 2008
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Ingår i: Genetical Research. - 1469-5073. ; 90:3, s. 223-228
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Tidskriftsartikel (refereegranskat)abstract
- In the Brassicaceae plant family, which includes the Arabidopsis and Brassica genera, self-incompatibility (SI) is controlled by genes at the S locus. Using experimental crosses, we studied the pattern of inheritance of S-locus alleles in the wild species Brassica cretica. Four full-sib families were established and unequal segregation of alleles at the SRK SI gene was found in one family. The segregation distortion acted in favour of a recessive (class II) allele and was best explained by some form of gametic-level selection. Our findings are discussed in the light of theoretical predictions of differential accumulation of deleterious mutations among S-locus alleles.
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| 2. |
- Alvarez-Castro, Jose, et al.
(författare)
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Modelling of genetic interactions improves prediction of hybrid patterns : a case study in domestic fowl
- 2012
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Ingår i: Genetical Research. - 0016-6723 .- 1469-5073. ; 94:5, s. 255-266
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Tidskriftsartikel (refereegranskat)abstract
- Summary A major challenge in complex trait genetics is to unravel how multiple loci and environmental factors together cause phenotypic diversity. Both first (F1) and second (F2) generation hybrids often display phenotypes that deviate from what is expected under intermediate inheritance. We have here studied two chicken F2 populations generated by crossing divergent chicken lines to assess how epistatic loci, identified in earlier quantitative trait locus (QTL) studies, contribute to hybrid deviations from the mid-parent phenotype. Empirical evidence suggests that the average phenotypes of the intercross birds tend to be lower than the midpoint between the parental means in both crosses. Our results confirm that epistatic interactions, despite a relatively small contribution to the phenotypic variance, play an important role in the deviation of hybrid phenotypes from the mid-parent values (i.e. multi-locus hybrid genotypes lead to lower rather than higher body weights). To a lesser extent, dominance also appears to contribute to the mid-parent deviation, at least in one of the crosses. This observation coincides with the hypothesis that hybridization tends to break up co-adapted gene complexes, i.e. generate Bateson-Dobzhansky-Muller incompatibilities.
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| 3. |
- Anisimov, Sergey
(författare)
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A large-scale screening of the normalized mammalian mitochondrial gene expression profiles.
- 2005
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Ingår i: Genetical Research. - 1469-5073. ; 86:2, s. 127-138
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Tidskriftsartikel (refereegranskat)abstract
- Mammalian mitochondrial genomes are organized in a conserved and extremely compact manner, encoding molecules that play a vital role in oxidative phosphorylation (OXPHOS) and carry out a number of other important biological functions. A large-scale screening of the normalized mitochondrial gene expression profiles generated from publicly available mammalian serial analysis of gene expression (SAGE) datasets (over 17·7 millions of tags) was performed in this study. Acquired SAGE libraries represent an extensive range of human, mouse, rat, bovine and swine cell and tissue samples (normal and pathological) in a variety of conditions. Using a straightforward in silico algorithm, variations in total mitochondrial gene expression, as well as in the expression of individual genes encoded by mitochondrial genomes are addressed, and common patterns in the species- and tissue-specific mitochondrial gene expression profiles are discussed.
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| 4. |
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| 5. |
- Bengtsson, Bengt Olle, et al.
(författare)
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A DNA marker for the duplicated cytosolic PGI genes in sheep's fescue (Festuca ovina L.)
- 2000
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Ingår i: Genetical Research. - 1469-5073. ; 76:3, s. 319-322
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Tidskriftsartikel (refereegranskat)abstract
- Active duplicate PgiC genes in sheep's fescue, Festuca ovina, are associated with a PCR marker of specific length (about 370 bp, of which 231 are in an intron). Using this marker, the frequency of plants with duplicate genes is estimated to be about 10% in a population from southern Sweden. The close molecular similarity between the electrophoretically different duplicated genes is in accordance with the conclusion reached earlier that they are indeed alleles at the same locus.
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| 6. |
- Ceplitis, Alf
(författare)
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Coalescence times and the Meselson effect in asexual eukaryotes
- 2003
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Ingår i: Genetical Research. - 1469-5073. ; 82:3, s. 183-190
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Tidskriftsartikel (refereegranskat)abstract
- In asexual eukaryotes, the two allelic gene copies at a locus are expected to become highly divergent as a result of the independent accumulation of mutations in the absence of segregation. If sexual reproduction was abandoned millions of generations ago, intra-individual allelic divergences can be significantly larger than in species that reproduce sexually. Owing to the disputed existence of truly ancient asexual species, this so-called 'Meselson effect' has been put forward as a means of confirming the complete loss of sexual reproduction. Very few attempts have, however, been made at quantifying the effect of sexual reproduction on the degree of divergence between gene copies in an asexual population. Here, I describe how asexual reproduction can be regarded as a special case of population subdivision. Using a slightly modified version of the standard two-deme structured coalescent, I derive the expected coalescence time for a pair of gene copies in an asexual population and show that the Meselson effect is compatible with low rates of sexual reproduction.
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| 7. |
- Felleki, Majbritt, et al.
(författare)
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Estimation of breeding values for mean and dispersion, their variance and correlation using double hierarchical generalized linear models
- 2012
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Ingår i: Genetics Research. - : Cambridge University Press. - 0016-6723 .- 1469-5073. ; 94:6, s. 307-317
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Tidskriftsartikel (refereegranskat)abstract
- The possibility of breeding for uniform individuals by selecting animals expressing a small response to environment has been studied extensively in animal breeding. Bayesian methods for fitting models with genetic components in the residual variance have been developed for this purpose, but have limitations due to the computational demands. We use the hierarchical (h)-likelihood from the theory of double hierarchical generalized linear models (DHGLM) to derive an estimation algorithm that is computationally feasible for large datasets. Random effects for both the mean and residual variance parts of the model are estimated together with their variance/covariance components. An important feature of the algorithm is that it can fit a correlation between the random effects for mean and variance. An h-likelihood estimator is implemented in the R software and an iterative reweighted least square (IRWLS) approximation of the h-likelihood is implemented using ASReml. The difference in variance component estimates between the two implementations is investigated, as well as the potential bias of the methods, using simulations. IRWLS gives the same results as h-likelihood in simple cases with no severe indication of bias. For more complex cases, only IRWLS could be used, and bias did appear. The IRWLS is applied on the pig litter size data previously analysed by Sorensen & Waagepetersen (2003) using Bayesian methodology. The estimates we obtained by using IRWLS are similar to theirs, with the estimated correlation between the random genetic effects being −0·52 for IRWLS and −0·62 in Sorensen & Waagepetersen (2003).
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| 8. |
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| 9. |
- Jacobsson, Lina, et al.
(författare)
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Many QTLs with minor additive effects are associated with a large difference in growth between two selection lines in chickens
- 2005
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Ingår i: Genetical Research. - 0016-6723 .- 1469-5073. ; 86:2, s. 115-125
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Tidskriftsartikel (refereegranskat)abstract
- Two growth-selected lines in chickens have been developed from a single founder population bydivergent selection for body weight at 56 days of age. After more than 40 generations of selectionthey show a nine-fold difference in body weight at selection age and large differences in growth rate,appetite, fat deposition and metabolic characteristics. We have generated a large intercross betweenthese lines comprising more than 800 F2 birds. QTL mapping revealed 13 loci affecting growth.The most striking observation was that the allele in the high weight line in all cases was associatedwith enhanced growth, but each locus explained only a small proportion of the phenotypic varianceusing a standard QTL model (1.3–3.1%). This result is in sharp contrast to our previous studywhere we reported that the two-fold difference in adult body size between the red junglefowl andWhite Leghorn domestic chickens is explained by a small number of QTLs with large additiveeffects. Furthermore, no QTLs for anorexia or antibody response were detected despite largedifferences for these traits between the founder lines. The result is an excellent example where alarge phenotypic difference between populations occurs in the apparent absence of any single locuswith large phenotypic effects. The study underscores the need for powerful experimental designs ingenetic studies of multifactorial traits. No QTL at all would have reached genome-wide significanceusing a less powerful design (e.g. approx. 200 F2 individuals) regardless of the nine-fold phenotypicdifference between the founder lines for the selected trait.
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| 10. |
- Kawabe, Akira, et al.
(författare)
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Comparative gene mapping in Arabidopsis lyrata chromosomes 6 and 7 and A. thaliana chromosome IV : Evolutionary history, rearrangements and local recombination rates
- 2006
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Ingår i: Genetical Research. - 0016-6723 .- 1469-5073. ; 88:1, s. 45-56
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Tidskriftsartikel (refereegranskat)abstract
- We have increased the density of genetic markers on the Arabidopsis lyrata chromosomes AL6 and AL7 corresponding to the A. thaliana chromosome IV, in order to determine chromosome rearrangements between these two species, and to compare recombination fractions across the same intervals. We confirm the two rearrangements previously inferred (a reciprocal translocation and a large inversion, which we infer to be pericentric). By including markers around the centromere regions of A. thaliana chromosomes IV and V, we localize the AL6 centromere, and can localize the breakpoints of these chromosome rearrangements more precisely than previously. One translocation breakpoint was close to the centromere, and the other coincided with one end of the inversion, suggesting that a single event caused both rearrangements. At the resolution of our mapping, apart from these rearrangements, all other markers are in the same order in A. lyrata and A. thaliana. We could thus compare recombination rates in the two species. We found slightly higher values in A. thaliana, and a minimum estimate for regions not close to a centromere in A. lyrata is 4-5 centimorgans per megabase. The mapped region of AL7 includes the self-incompatibility loci (S-loci), and this region has been predicted to have lower recombination than elsewhere in the genome. We mapped 17 markers in a region of 1·23 Mb surrounding these loci, and compared the approximately 600 kb closest to the S-loci with the surrounding region of approximately the same size. There were significantly fewer recombination events in the closer than the more distant region, supporting the above prediction, but showing that the low recombination region is very limited in size. © 2006 Cambridge University Press.
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