199,517 research outputs found
Inheritance of Suri and Huacaya type of fleece in Alpaca
No full textBackground
Genetic improvement of fibre-producing animal species has often induced transition from double coated to single coated fleece, accompanied by dramatic changes in skin follicles and hair composition, likely implying variation at multiple loci. Huacaya, the more common fleece phenotype in alpaca (Vicugna pacos), is characterized by a thick dense coat growing perpendicularly from the body, whereas the alternative rare and more prized single-coated Suri phenotype is distinguished by long silky fiber that
grows parallel to the body and hangs in separate, distinctive pencil locks. A singlelocus genetic model has been proposed for the Suri-Huacaya phenotype, where Huacaya is recessive.
Methods
Two reciprocal experimental test-crosses (Suri x Huacaya) were carried out, involving a total of 17 unrelated males and 149 unrelated females. An additional dataset of 587
offspring of Suri x Suri crosses was analyzed. Segregation ratios, population genotype frequencies, and/or recombination fraction under different genetic models were
estimated by maximum likelihood.
Results
The single locus model for the Suri/Huacaya phenotype is rejected. In addition, we present two unexpected observations: 1) a large proportion (about 3⁄4) of the Suri
animals is hybrid (with at least one Huacaya offspring), even in rearing conditions where the Huacaya trait would have been almost eliminated; 2) a model with two different values of the segregation ratio fit the data significantly better than a model with a single parameter
Whole genome sequencing analysis of alpaca suggests TRPV3 as a candidate gene for the suri phenotype
No full textBackground: Alpaca is a domestic South American camelid probably arising from the domestication of two wild camelids, the vicugna and the guanaco. Two phenotypes are described for alpaca, known as huacaya and suri. Huacaya fleece is characterized by compact, soft, and highly crimped fibers, while suri fleece is longer, straight, less crimped, and lustrous. The gene variants determining these phenotypes are still unknown, although previous studies suggested a dominant inheritance of the suri. Based on that, the aim of this study was the identification of the gene variants determining alpaca coat phenotypes through whole genome sequencing (WGS) analysis. Results: The sample used includes two test-cross alpaca families, suri × huacaya, which produced two offspring, one with the suri phenotype and one with the huacaya phenotype. The analyzed sample was expanded through the addition of WGS data from six vicugnas and six guanacos; this because we assumed the absence of the gene variants linked to the suri phenotype in these wild species. The analysis of gene variant segregation with the suri phenotype, coupled with the filtering of gene variants present in the wild species, disclosed the presence in all the suri samples of a premature termination codon (PTC) in TRPV3 (transient receptor potential cation channel subfamily V member 3), a gene known to be involved in hair growth and cycling, thermal sensation, cold tolerance and adaptation in several species. Mutations in TRPV3 were previously associated with the alteration of hair structure leading to an impaired formation of the hair canal and the hair shaft in mouse. This PTC in TRPV3, due to a G > T substitution (p.Glu475*), results in a loss of 290 amino acids from the canonical translated protein, plausibly leading to a physiological dysfunction. Conclusion: The present results suggest that the suri phenotype may arise from a TRPV3 gene variant which may explain some of the suri features such as its longer hair fibre with lower number of cuticular scales compared to huacaya
Suri/Huacaya phenotype inheritance in alpaca (Vicugna pacos)
No full textThe Suri/Huacaya phenotype inheritance in alpaca was tested on rwo indipendent Peruvian sources of records: the Registry of Mallkin farm (588 offspring by Suri sire x Suri dam from 62 paternal half sib families, and 2,126 offspring by Huacaya sire x Huacaya dam froom 177 paternal half sib families) and the results of the Quimsachata INIA ILPA Puno experimental trial (two reciprocal experimental test-crosses, involving a total of 17 unrelated males and 149 unrelated females). The data support a genetic model in which two linked loci must simultaneously be homozigous for recessive alleles in order to produce Huacaya phenotype. The estimated recombination rate between these loci was 0.099 (95%C.L. =0.029-0.204). The Birth of 3 Suri offspring from Huacaya x Huacaya mating is explained by a new mutation on some germinal lines of Huacaya animals. The direct mutation can be estimated at 0.001
Spatial structure of skin follicles in Suri and Huacaya alpacas
No full textThe present study aimed at characterizing the type and arrangement of skin follicles of Suri and Huacaya alpaca. Samples (11 Suri and 10 Huacaya) were collected by punch skin biopsy from the midside of alpaca and processed for histological study. Each biopsy was examined using projection microscope. Follicular groups were identified and the position of each secondary and primary follicle was recorded. The ratio of secondary to primary follicles (S/P ratio) was compared between breeds using the Wilcoxon test. The spatial structure of the follicles was analyzed with Ripley's K function and the L function. To detect deviations from Complete Spatial Randomness at different spatial scales simulated confidence envelopes were calculated. The S/P ratio did not differ between Huacaya (7.1 ± 0.52) and Suri (7.21 ± 0.62). There is evidence of statistically significant spatial structure of the follicles in both breeds at small spatial scales. However, at a higher spatial scale, the proportion of samples with a clustered spatial structure of follicles was significantly higher in Huacaya. The study of skin follicles spatial pattern opens up new possibilities for improving knowledge of the potential role of skin follicle in alpaca fibre production. © 2016 Elsevier B.V
- …
