| 1. |
- Wade, C. M., et al.
(författare)
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Genome Sequence, Comparative Analysis, and Population Genetics of the Domestic Horse
- 2009
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 326:5954, s. 865-867
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Tidskriftsartikel (refereegranskat)abstract
- We report a high-quality draft sequence of the genome of the horse ( Equus caballus). The genome is relatively repetitive but has little segmental duplication. Chromosomes appear to have undergone few historical rearrangements: 53% of equine chromosomes show conserved synteny to a single human chromosome. Equine chromosome 11 is shown to have an evolutionary new centromere devoid of centromeric satellite DNA, suggesting that centromeric function may arise before satellite repeat accumulation. Linkage disequilibrium, showing the influences of early domestication of large herds of female horses, is intermediate in length between dog and human, and there is long-range haplotype sharing among breeds.
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| 2. |
- Karlsson, Elinor K., et al.
(författare)
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Efficient mapping of mendelian traits in dogs through genome-wide association
- 2007
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Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1061-4036 .- 1546-1718. ; 39:11, s. 1321-1328
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Tidskriftsartikel (refereegranskat)abstract
- With several hundred genetic diseases and an advantageous genome structure, dogs are ideal for mapping genes that cause disease. Here we report the development of a genotyping array with |[sim]|27,000 SNPs and show that genome-wide association mapping of mendelian traits in dog breeds can be achieved with only |[sim]|20 dogs. Specifically, we map two traits with mendelian inheritance: the major white spotting (S) locus and the hair ridge in Rhodesian ridgebacks. For both traits, we map the loci to discrete regions of <1 Mb. Fine-mapping of the S locus in two breeds refines the localization to a region of |[sim]|100 kb contained within the pigmentation-related gene MITF. Complete sequencing of the white and solid haplotypes identifies candidate regulatory mutations in the melanocyte-specific promoter of MITF. Our results show that genome-wide association mapping within dog breeds, followed by fine-mapping across multiple breeds, will be highly efficient and generally applicable to trait mapping, providing insights into canine and human health.
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| 3. |
- Imsland, Freyja, et al.
(författare)
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The Rose-comb Mutation in Chickens Constitutes a Structural Rearrangement Causing Both Altered Comb Morphology and Defective Sperm Motility
- 2012
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Ingår i: PLOS Genetics. - : Public Library of Science (PLoS). - 1553-7404 .- 1553-7390. ; 8:6, s. e1002775-
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Tidskriftsartikel (refereegranskat)abstract
- Rose-comb, a classical monogenic trait of chickens, is characterized by a drastically altered comb morphology compared to the single-combed wild-type. Here we show that Rose-comb is caused by a 7.4 Mb inversion on chromosome 7 and that a second Rose-comb allele arose by unequal crossing over between a Rose-comb and wild-type chromosome. The comb phenotype is caused by the relocalization of the MNR2 homeodomain protein gene leading to transient ectopic expression of MNR2 during comb development. We also provide a molecular explanation for the first example of epistatic interaction reported by Bateson and Punnett 104 years ago, namely that walnut-comb is caused by the combined effects of the Rose-comb and Pea-comb alleles. Transient ectopic expression of MNR2 and SOX5 (causing the Pea-comb phenotype) occurs in the same population of mesenchymal cells and with at least partially overlapping expression in individual cells in the comb primordium. Rose-comb has pleiotropic effects, as homozygosity in males has been associated with poor sperm motility. We postulate that this is caused by the disruption of the CCDC108 gene located at one of the inversion breakpoints. CCDC108 is a poorly characterized protein, but it contains a MSP (major sperm protein) domain and is expressed in testis. The study illustrates several characteristic features of the genetic diversity present in domestic animals, including the evolution of alleles by two or more consecutive mutations and the fact that structural changes have contributed to fast phenotypic evolution.
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| 4. |
- Rubin, Carl-Johan, et al.
(författare)
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Whole genome resequencing reveals loci under selection during chicken domestication
- 2010
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Ingår i: Nature. - London : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 464:7288, s. 587-591
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Tidskriftsartikel (refereegranskat)abstract
- Domestic animals are excellent models for genetic studies of phenotypic evolution. They have evolved genetic adaptations to a new environment, the farm, and have been subjected to strong human-driven selection leading to remarkable phenotypic changes in morphology, physiology and behaviour. Identifying the genetic changes underlying these developments provides new insight into general mechanisms by which genetic variation shapes phenotypic diversity. Here we describe the use of massively parallel sequencing to identify selective sweeps of favourable alleles and candidate mutations that have had a prominent role in the domestication of chickens (Gallus gallus domesticus) and their subsequent specialization into broiler (meat-producing) and layer (egg-producing) chickens. We have generated 44.5-fold coverage of the chicken genome using pools of genomic DNA representing eight different populations of domestic chickens as well as red jungle fowl (Gallus gallus), the major wild ancestor. We report more than 7,000,000 single nucleotide polymorphisms, almost 1,300 deletions and a number of putative selective sweeps. One of the most striking selective sweeps found in all domestic chickens occurred at the locus for thyroid stimulating hormone receptor (TSHR), which has a pivotal role in metabolic regulation and photoperiod control of reproduction in vertebrates. Several of the selective sweeps detected in broilers overlapped genes associated with growth, appetite and metabolic regulation. We found little evidence that selection for loss-of-function mutations had a prominent role in chicken domestication, but we detected two deletions in coding sequences that we suggest are functionally important. This study has direct application to animal breeding and enhances the importance of the domestic chicken as a model organism for biomedical research.
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| 5. |
- Zody, Michael C., 1968-
(författare)
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Investigation of Mechanics of Mutation and Selection by Comparative Sequencing
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The process of evolution is of both scientific and medical interest. This thesis presents several studies using complete genomic reference sequences, comparative genomic data, and intraspecific diversity data to study the two key processes of evolution: mutation and selection. Large duplications, deletions, inversions, and translocations of DNA contribute to genomic variation both between and within species. Human chromosomes 15 and 17 contain a high percentage of dispersed, recently duplicated sequences. Examination of the relationships between these sequences showed that the majority of all duplications within each chromosome could be linked through core sequences that are prone to duplication. Comparison to orthologous sequences in other mammals allowed a reconstruction of the ancestral state of the human chromosomes, revealing that regions of rearrangement specific to the human lineage are highly enriched in chromosome-specific duplications. Comparison to copy number variation data from other studies also shows that these regions are enriched in current human structural variation. One specific region, the MAPT locus at 17q21.31, known to contain an inversion polymorphism in Europeans, was resequenced completely across both human orientation haplotypes and in chimpanzee and orangutan, revealing complex duplication structures at the inversion breakpoints, with the human region being more complex than chimpanzee or orangutan. Fluorescent in-situ hybridization analysis of human, chimpanzee, and orangutan chromosomes showed inversion polymorphisms of independent origin in all three species, demonstrating that this region has been a hotspot of genomic rearrangement for at least twelve million years. These results reveal a mechanistic relationship between sequence duplication and rearrangement in the great apes. We also generated a draft sequence of the chimpanzee genome and compared it to that of the human. Among other findings, this showed that CpG dinucleotides contribute 25% of all single base mutations, with a rate of mutation ~10-fold that of other bases, and that the male mutation rate in great apes is ~5-6 times the female rate, a higher ratio than had been observed in comparisons of primates and rodents. We detected six regions of probable recent positive selection in humans with a statistical method relying on chimpanzee sequence to control for regional variation in mutation rates. Finally, resequencing of several lines of domestic chicken and comparison to the reference chicken genome identified a number of gene deletions fixed in domestic lines and also several potential selective sweeps. Of particular interest are a missense mutation in TSHR nearly fixed in all domestic chickens and a partial deletion of SH3RF2 fixed in a high growth line. The TSHR mutation may play a role in relaxation of seasonal reproduction. A high-resolution QTL mapping experiment showed that the SH3RF2 deletion is significantly associated with increased growth. This work provides important new insights into the mechanics of evolutionary change at both the single nucleotide and structural level and identifies potential targets of natural and artificial selection in humans and chickens.
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