Identification of the Single Base Change Causing the Callipyge Muscle Hypertrophy Phenotype, the Only Known Example of Polar Overdominance in Mammals

Freking, B. A.; Murphy, Susan K.; Wylie, Andrew; Rhodes, Simon J.; Keele, J. W.; Leymaster, K. A.; Jirtle, Randy L.; Smith, Timothy P. L.

doi:10.1101/gr.571002

Cited by 204 publications

(162 citation statements)

References 37 publications

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“…Our analysis placed the gene WARS near the DLK1/GTL2 imprinting domain on chromosome 18 (Figure 6), which also contains the widely-studied sheep Callipyge ( CLPG ) locus [45], expressed from the dominant paternal allele [46]. Six other imprinted genes have been identified in this region: paternally expressed DLK1, DAT , and RTL1 (also known as PEG11 ), and maternally expressed GTL2 (also known as MEG3), PEG11AS , and MEG8 .…”

Section: Discussionmentioning

confidence: 99%

Effects of maternal nutrition on the expression of genomic imprinted genes in ovine fetuses

et al. 2018

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Genomic imprinting is an epigenetic phenomenon of differential allelic expression based on parental origin. To date, 263 imprinted genes have been identified among all investigated mammalian species. However, only 21 have been described in sheep, of which 11 are annotated in the current ovine genome. Here, we aim to i) use DNA/RNA high throughput sequencing to identify new monoallelically expressed and imprinted genes in day 135 ovine fetuses and ii) determine whether maternal diet (100%, 60%, or 140% of National Research Council Total Digestible Nutrients) influences expression of imprinted genes. We also reported strategies to solve technical challenges in the data analysis pipeline. We identified 80 monoallelically expressed, 13 new putative imprinted genes, and five known imprinted genes in sheep using the 263 genes stated above as a guide. Sanger sequencing confirmed allelic expression of seven genes, CASD1, COPG2, DIRAS3, INPP5F, PLAGL1, PPP1R9A, and SLC22A18. Among the 13 putative imprinted genes, five were localized in the known sheep imprinting domains of MEST on chromosome 4, DLK1/GTL2 on chromosome 18 and KCNQ1 on chromosome 21, and three were in a novel sheep imprinted cluster on chromosome 4, known in other species as PEG10/SGCE. The expression of DIRAS3, IGF2, PHLDA2, and SLC22A18 was altered by maternal diet, albeit without allelic expression reversal. Together, our results expanded the list of sheep imprinted genes to 34 and demonstrated that while the expression levels of four imprinted genes were changed by maternal diet, the allelic expression patterns were un-changed for all imprinted genes studied.

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Section: Discussionmentioning

confidence: 99%

Effects of maternal nutrition on the expression of genomic imprinted genes in ovine fetuses

et al. 2018

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“…Recently, a decade-long positional cloning effort to identify the CLPG mutation came to fruition with the identification of an A-to-G transition that segregates perfectly with the CLPG allele [20,53]. This polymorphism, which is designated as SNP CLPG , lies within a conserved 12-bp motif that is located approximately 33 kb upstream of the GTL2 gene.…”

Section: The Callipyge (Clpg) Locusmentioning

confidence: 99%

The callipyge mutation and other genes that affect muscle hypertrophy in sheep

et al. 2005

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-Genetic strategies to improve the profitability of sheep operations have generally focused on traits for reproduction. However, natural mutations exist in sheep that affect muscle growth and development, and the exploitation of these mutations in breeding strategies has the potential to significantly improve lamb-meat quality. The best-documented mutation for muscle development in sheep is callipyge (CLPG), which causes a postnatal muscle hypertrophy that is localized to the pelvic limbs and loin. Enhanced skeletal muscle growth is also observed in animals with the Carwell (or rib-eye muscling) mutation, and a double-muscling phenotype has been documented for animals of the Texel sheep breed. However, the actual mutations responsible for these muscular hypertrophy phenotypes in sheep have yet to be identified, and further characterization of the genetic basis for these phenotypes will provide insight into the biological control of muscle growth and body composition.sheep / muscle / hypertrophy / callipyge / mutation

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“…Imprinting tends to affect a region of a chromosome and it is therefore not unexpected that TM-QTL would be imprinted, given its position within the same region as both Carwell (Nicoll, 2007) and Callipyge (Cockett et al, 1994a;Charlier et al, 2001a;Freking et al, 2002) and the cluster of imprinted genes around Callipyge (Charlier et al, 2001b;Cockett et al, 1996b).…”

Section: Discussionmentioning

confidence: 99%

Effect and mode of action of the Texel muscling QTL (TM-QTL) on carcass traits in purebred Texel lambs

Macfarlane

Lambe

Matika

et al. 2014

animal

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TM-QTL is a quantitative trait locus (QTL) on ovine chromosome 18 (OAR18) known to affect loin muscling in Texel sheep. Previous work suggested that its mode of inheritance is consistent with paternal polar overdominance, but this has yet to be formally demonstrated. This study used purebred Texel sheep segregating for TM-QTL to confirm its presence in the chromosomal region in which it was first reported and to determine its pattern of inheritance. To do so, this study used the first available data from a Texel flock, which included homozygote TM-QTL carriers (TM/TM; n = 34) in addition to homozygote non-carriers (+ / + ; n = 40 and, heterozygote TM-QTL-carriers inheriting TM-QTL from their sire (TM/ + ; n = 53) or their dam (+ /TM; n = 17). Phenotypes included a wide range of loin muscling, carcass composition and tissue distribution traits. The presence of a QTL affecting ultrasound muscle depth on OAR18 was confirmed with a paternal QTL effect ranging from + 0.54 to + 2.82 mm UMD (s.e. 0.37 to 0.57 mm) across the sires segregating for TM-QTL. Loin muscle width, depth and area, loin muscle volume and dissected M. longissimus lumborum weight were significantly greater for TM/ + than + / + lambs (+2.9% to + 7.9%; P < 0.05). There was significant evidence that the effect of TM-QTL on the various loin muscling traits measured was paternally polar overdominant ( P < 0.05). In contrast, there was an additive effect of TM-QTL on both live weight at 20 weeks and carcass weight; TM/TM animals were significantly ( P < 0.05) heavier than + / + (+11.1% and + 7.3%, respectively) and + /TM animals (+11.9% and + 11.7%, respectively), with TM/ + intermediate. Weights of the leg, saddle and shoulder region (corrected for carcass weight) were similar in the genotypic groups. There was a tendency for lambs inheriting TM-QTL from their sire to be less fat with slightly more muscle than non-carriers. For example, carcass muscle weight measured by live animal CT-scanning was 2.8% higher in TM/ TM than + / + lambs ( P < 0.05), carcass muscle weight measured by carcass CT-scanning was 1.36% higher in TM/ + than + / + lambs ( P < 0.05), and weight of fat trimmed from the carcass cuts was significantly lower for TM/ + than + / + lambs (−11.2%; P < 0.05). No negative effects of TM-QTL on carcass traits were found. Optimal commercial use of TM-QTL within the sheep industry would require some consideration, due to the apparently different mode of action of the two main effects of TM-QTL (on growth and muscling).

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Identification of the Single Base Change Causing the Callipyge Muscle Hypertrophy Phenotype, the Only Known Example of Polar Overdominance in Mammals

Cited by 204 publications

References 37 publications

Effects of maternal nutrition on the expression of genomic imprinted genes in ovine fetuses

Effects of maternal nutrition on the expression of genomic imprinted genes in ovine fetuses

The callipyge mutation and other genes that affect muscle hypertrophy in sheep

Effect and mode of action of the Texel muscling QTL (TM-QTL) on carcass traits in purebred Texel lambs

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