| 1. |
- Eriksson, Jonas, et al.
(författare)
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Identification of the yellow skin gene reveals a hybrid origin of the domestic chicken
- 2008
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Ingår i: PLoS Genetics. - : Public Library of Science (PLoS). - 1553-7390 .- 1553-7404. ; 4:2, s. e1000010-
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Tidskriftsartikel (refereegranskat)abstract
- Yellow skin is an abundant phenotype among domestic chickens and is caused by a recessive allele (W*Y) that allows deposition of yellow carotenoids in the skin. Here we show that yellow skin is caused by one or more cis-acting and tissue-specific regulatory mutation(s) that inhibit expression of BCDO2 (beta-carotene dioxygenase 2) in skin. Our data imply that carotenoids are taken up from the circulation in both genotypes but are degraded by BCDO2 in skin from animals carrying the white skin allele (W*W). Surprisingly, our results demonstrate that yellow skin does not originate from the red junglefowl (Gallus gallus), the presumed sole wild ancestor of the domestic chicken, but most likely from the closely related grey junglefowl (Gallus sonneratii). This is the first conclusive evidence for a hybrid origin of the domestic chicken, and it has important implications for our views of the domestication process.
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| 2. |
- Schwochow, Doreen, et al.
(författare)
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The evolution of Sex-linked barring alleles in chickens involves both regulatory and coding changes in CDKN2A
- 2017
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Ingår i: PLOS Genetics. - : PUBLIC LIBRARY SCIENCE. - 1553-7390 .- 1553-7404. ; 13:4
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Tidskriftsartikel (refereegranskat)abstract
- Sex-linked barring is a fascinating plumage pattern in chickens recently shown to be associated with two non-coding and two missense mutations affecting the ARF transcript at the CDKN2A tumor suppressor locus. It however remained a mystery whether all four mutations are indeed causative and how they contribute to the barring phenotype. Here, we show that Sex-linked barring is genetically heterogeneous, and that the mutations form three functionally different variant alleles. The B0 allele carries only the two non-coding changes and is associated with the most dilute barring pattern, whereas the B1 and B2 alleles carry both the two non-coding changes and one each of the two missense mutations causing the Sex-linked barring and Sex-linked dilution phenotypes, respectively. The data are consistent with evolution of alleles where the non-coding changes occurred first followed by the two missense mutations that resulted in a phenotype more appealing to humans. We show that one or both of the non-coding changes are cis-regulatory mutations causing a higher CDKN2A expression, whereas the missense mutations reduce the ability of ARF to interact with MDM2. Caspase assays for all genotypes revealed no apoptotic events and our results are consistent with a recent study indicating that the loss of melanocyte progenitors in Sex-linked barring in chicken is caused by premature differentiation and not apoptosis. Our results show that CDKN2A is a major locus driving the differentiation of avian melanocytes in a temporal and spatial manner.
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| 3. |
- Wright, Dominic, et al.
(författare)
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Copy number variation in intron 1 of SOX5 causes the Pea-comb phenotype in chickens
- 2009
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Ingår i: PLoS Genetics. - : Public Library of Science (PLoS). - 1553-7390 .- 1553-7404. ; 5:6, s. e1000512-
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Tidskriftsartikel (refereegranskat)abstract
- Pea-comb is a dominant mutation in chickens that drastically reduces the size of the comb and wattles. It is an adaptive trait in cold climates as it reduces heat loss and makes the chicken less susceptible to frost lesions. Here we report that Pea-comb is caused by a massive amplification of a duplicated sequence located near evolutionary conserved non-coding sequences in intron 1 of the gene encoding the SOX5 transcription factor. This must be the causative mutation since all other polymorphisms associated with the Pea-comb allele were excluded by genetic analysis. SOX5 controls cell fate and differentiation and is essential for skeletal development, chondrocyte differentiation, and extracellular matrix production. Immunostaining in early embryos demonstrated that Pea-comb is associated with ectopic expression of SOX5 in mesenchymal cells located just beneath the surface ectoderm where the comb and wattles will subsequently develop. The results imply that the duplication expansion interferes with the regulation of SOX5 expression during the differentiation of cells crucial for the development of comb and wattles. The study provides novel insight into the nature of mutations that contribute to phenotypic evolution and is the first description of a spontaneous and fully viable mutation in this developmentally important gene.
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| 4. |
- Ahanda, Marie-Laure Endale, et al.
(författare)
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Non-coding RNAs revealed during identification of genes involved in chicken immune responses
- 2009
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Ingår i: Immunogenetics. - : Springer Science and Business Media LLC. - 1432-1211 .- 0093-7711. ; 61:1, s. 55-70
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Tidskriftsartikel (refereegranskat)abstract
- Recent large-scale cDNA cloning studies have shown that a significant proportion of the transcripts expressed from vertebrate genomes do not appear to encode protein. Moreover, it was reported in mammals (human and mice) that these non-coding transcripts are expressed and regulated by mechanisms similar to those involved in the control of protein-coding genes. We have produced a collection of cDNA sequences from immunologically active tissues with the aim of discovering chicken genes involved in immune mechanisms, and we decided to explore the non-coding component of these immune-related libraries. After finding known non-coding RNAs (miRNA, snRNA, snoRNA), we identified new putative mRNA-like non-coding RNAs. We characterised their expression profiles in immune-related samples. Some of them showed changes in expression following viral infections. As they exhibit patterns of expression that parallel the behaviour of protein-coding RNAs in immune tissues, our study suggests that they could play an active role in the immune response.
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| 5. |
- Bi, Huijuan, et al.
(författare)
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A frame-shift mutation in COMTD1 is associated with impaired pheomelanin pigmentation in chicken
- 2023
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Ingår i: PLOS Genetics. - : Public Library of Science (PLoS). - 1553-7390 .- 1553-7404. ; 19:4
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Tidskriftsartikel (refereegranskat)abstract
- The biochemical pathway regulating the synthesis of yellow/red pheomelanin is less well characterized than the synthesis of black/brown eumelanin. Inhibitor of gold (IG phenotype) is a plumage colour variant in chicken that provides an opportunity to further explore this pathway since the recessive allele (IG) at this locus is associated with a defect in the production of pheomelanin. IG/IG homozygotes display a marked dilution of red pheomelanin pigmentation, whilst black pigmentation (eumelanin) is only slightly affected. Here we show that a 2-base pair insertion (frame-shift mutation) in the 5th exon of the Catechol-O-methyltransferase containing domain 1 gene (COMTD1), expected to cause a complete or partial loss-of-function of the COMTD1 enzyme, shows complete concordance with the IG phenotype within and across breeds. We show that the COMTD1 protein is localized to mitochondria in pigment cells. Knockout of Comtd1 in a mouse melanocytic cell line results in a reduction in pheomelanin metabolites and significant alterations in metabolites of glutamate/glutathione, riboflavin, and the tricarboxylic acid cycle. Furthermore, COMTD1 overexpression enhanced cellular proliferation following chemical-induced transfection, a potential inducer of oxidative stress. These observations suggest that COMTD1 plays a protective role for melanocytes against oxidative stress and that this supports their ability to produce pheomelanin.
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| 6. |
- Boije, Henrik, et al.
(författare)
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Sonic Hedgehog-Signalling Patterns the Developing Chicken Comb as Revealed by Exploration of the Pea-comb Mutation
- 2012
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 7:12, s. e50890-
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Tidskriftsartikel (refereegranskat)abstract
- The genetic basis and mechanisms behind the morphological variation observed throughout the animal kingdom is stillrelatively unknown. In the present work we have focused on the establishment of the chicken comb-morphology byexploring the Pea-comb mutant. The wild-type single-comb is reduced in size and distorted in the Pea-comb mutant. Peacombis formed by a lateral expansion of the central comb anlage into three ridges and is caused by a mutation in SOX5,which induces ectopic expression of the SOX5 transcription factor in mesenchyme under the developing comb. Analysis ofdifferential gene expression identified decreased Sonic hedgehog (SHH) receptor expression in Pea-comb mesenchyme. Byexperimentally blocking SHH with cyclopamine, the wild-type single-comb was transformed into a Pea-comb-likephenotype. The results show that the patterning of the chicken comb is under the control of SHH and suggest that ectopicSOX5 expression in the Pea-comb change the response of mesenchyme to SHH signalling with altered combmorphogenesis as a result. A role for the mesenchyme during comb morphogenesis is further supported by the recentfinding that another comb-mutant (Rose-comb), is caused by ectopic expression of a transcription factor in combmesenchyme. The present study does not only give knowledge about how the chicken comb is formed, it also adds to ourunderstanding how mutations or genetic polymorphisms may contribute to inherited variations in the human face.
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| 7. |
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| 8. |
- Gunnarsson, Ulrika, et al.
(författare)
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Mutations in SLC45A2 Cause Plumage Color Variation in Chicken and Japanese Quail
- 2007
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Ingår i: Genetics. - : Oxford University Press (OUP). - 0016-6731 .- 1943-2631. ; 175:2, s. 867-877
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Tidskriftsartikel (refereegranskat)abstract
- S*S (Silver), S*N (wild type/gold), and S*AL (sex-linked imperfect albinism) form a series of alleles at the S (Silver) locus on chicken (Gallus gallus) chromosome Z. Similarly, sex-linked imperfect albinism (AL*A) is the bottom recessive allele at the orthologous AL locus in Japanese quail (Coturnix japonica). The solute carrier family 45, member 2, protein (SLC45A2), previously denoted membrane-associated transporter protein (MATP), has an important role in vesicle sorting in the melanocytes. Here we report five SLC45A2 mutations. The 106delT mutation in the chicken S*AL allele results in a frameshift and a premature stop codon and the corresponding mRNA appears to be degraded by nonsense-mediated mRNA decay. A splice-site mutation in the Japanese quail AL*A allele causes in-frame skipping of exon 4. Two independent missense mutations (Tyr277Cys and Leu347Met) were associated with the Silver allele in chicken. The functional significance of the former mutation, associated only with Silver in White Leghorn, is unclear. Ala72Asp was associated with the cinnamon allele (AL*C) in the Japanese quail. The most interesting feature concerning the SLC45A2 variants documented in this study is the specific inhibition of expression of red pheomelanin in Silver chickens. This phenotypic effect cannot be explained on the basis of the current, incomplete, understanding of SLC45A2 function. It is an enigma why recessive null mutations at this locus cause an almost complete absence of both eumelanin and pheomelanin whereas some missense mutations are dominant and cause a specific inhibition of pheomelanin production.
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| 9. |
- Gunnarsson, Ulrika, et al.
(författare)
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The Dark brown plumage color in chickens is caused by an 8.3 kb deletion upstream of SOX10.
- 2011
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Ingår i: Pigment cell & melanoma research. - 1755-148X .- 1755-1471.
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Tidskriftsartikel (refereegranskat)abstract
- The Dark brown mutation in chickens reduces expression of black eumelanin and enhances expression of red pheomelanin but only in certain parts of the plumage. Here we present genetic evidence that an 8.3 kb deletion upstream of the SOX10 transcription start site is the causal mutation underlying the Dark brown phenotype. The SOX10 transcription factor has a well-established role in melanocyte biology and is essential for melanocyte migration and survival. Previous studies have demonstrated that the mouse homolog of a highly conserved element within the deleted region is a SOX10 enhancer. The mechanism of action of this mutation remains to be established but one possible scenario is that the deletion leads to reduced SOX10 expression which in turn down-regulates expression of key enzymes in pigment synthesis such as tyrosinase. Lower tyrosinase activity leads to a shift towards a more pheomelanistic (reddish) plumage color, which is the characteristic feature of the Dark brown phenotype.
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| 10. |
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| 11. |
- Hellström, Anders R., et al.
(författare)
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Sex-linked barring in chickens is controlled by the CDKN2A/B tumour suppressor locus
- 2010
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Ingår i: Pigment Cell and Melanoma Research. - : Blackwell Publishing Group. - 1755-1471 .- 1755-148X. ; 23:4, s. 521-530
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Tidskriftsartikel (refereegranskat)abstract
- Sex-linked barring, a common plumage colour found in chickens, is characterized by black and white barred feathers. Previous studies have indicated that the white bands are caused by an absence of melanocytes in the feather follicle during the growth of this region. Here we show that Sex-linked barring is controlled by the CDKN2A/B locus, which encodes the INK4b and ARF transcripts. We identified two non-coding mutations in CDKN2A that showed near complete association with the phenotype. Also identified were two missense mutations at highly conserved sites, V9D and R10C, and every bird tested with a confirmed Sex-linked barring phenotype carried one of these missense mutations. Further work is required to determine if one of these or a combined effect of two or more CDKN2A mutations is causing Sex-linked barring. This novel finding provides the first evidence that the tumour suppressor locus CDKN2A/B can affect pigmentation phenotypes and sheds new light on the functional significance of this gene.
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| 12. |
- 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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| 13. |
- Li, Jingyi, et al.
(författare)
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A missense mutation in TYRP1 causes the chocolate plumage color in chicken and alters melanosome structure
- 2019
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Ingår i: Pigment Cell & Melanoma Research. - : WILEY. - 1755-1471 .- 1755-148X. ; 32:3, s. 381-390
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Tidskriftsartikel (refereegranskat)abstract
- The chocolate plumage color in chickens is due to a sex-linked recessive mutation, choc, which dilutes eumelanin pigmentation. Because TYRP1 is sex-linked in chickens, and TYRP1 mutations determine brown coat color in mammals, TYRP1 appeared as the obvious candidate gene for the choc mutation. By combining gene mapping with gene capture, a complete association was identified between the chocolate phenotype and a missense mutation leading to a His214Asn change in the ZnA zinc-binding domain of the protein. A diagnostic test confirmed complete association by screening 428 non-chocolate chickens of various origins. This is the first TYRP1 mutation described in the chicken. Electron microscopy analysis showed that melanosomes were more numerous in feather follicles of chocolate chickens but exhibited an abnormal structure characterized by a granular content and an irregular shape. A similar altered morphology was observed on melanosomes of another TYRP1 mutant in birds, the roux mutation of the quail.
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| 14. |
- 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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| 15. |
- Schwochow, Doreen, et al.
(författare)
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The feather pattern autosomal barring in chicken is strongly associated with segregation at the MC1R locus
- 2021
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Ingår i: Pigment Cell & Melanoma Research. - : John Wiley & Sons. - 1755-1471 .- 1755-148X. ; 34:6, s. 1015-1028
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Tidskriftsartikel (refereegranskat)abstract
- Color patterns within individual feathers are common in birds but little is known about the genetic mechanisms causing such patterns. Here, we investigate the genetic basis for autosomal barring in chicken, a horizontal striping pattern on individual feathers. Using an informative backcross, we demonstrate that the MC1R locus is strongly associated with this phenotype. A deletion at SOX10, underlying the dark brown phenotype on its own, affects the manifestation of the barring pattern. The coding variant L133Q in MC1R is the most likely causal mutation for autosomal barring in this pedigree. Furthermore, a genetic screen across six different breeds showing different patterning phenotypes revealed that the most striking shared characteristics among these breeds were that they all carried the MC1R alleles Birchen or brown. Our data suggest that the presence of activating MC1R mutations enhancing pigment synthesis is an important mechanism underlying pigmentation patterns on individual feathers in chicken. We propose that MC1R and its antagonist ASIP play a critical role for determining within-feather pigmentation patterns in birds by acting as activator and inhibitor possibly in a Turing reaction-diffusion model.
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