Color Genetics

  • A Missense Mutation in the Agouti Signaling Protein Gene (ASIP) is Associated with the No Light Points Coat Phenotype in Donkeys

    Seven donkey breeds are recognized by the French studbook and are characterized by a black, bay or grey coat colour including light cream-to-white points (LP). Occasionally, Normand bay donkeys give birth to dark foals that lack LP and display the no light points (NLP) pattern. This pattern is more frequent and officially recognized in American miniature donkeys. The LP (or pangare) phenotype resembles that of the light bellied agouti pattern in mouse, while the NLP pattern resembles that of the mammalian recessive black phenotype; both phenotypes are associated with the agouti signaling protein gene (ASIP). more »
  • Alpaca Color Genetics: The Genetics of White Markings

    To make predictions about coat color, or almost any other trait, in cria from specific breedings you need to understand some basic rules of genetics. Coat color is determined by genetics. When people say something is genetically determined, what they are really talking about is DNA. DNA is what codes for all of the proteins (things like hemoglobin, albumin, melanin, insulin, keratin tissues, hormones all the stuff that make up an alpaca), and for the instructions on how, when and where to make these proteins within the alpaca. Segments of DNA that code for proteins are called genes. more »
  • Alpaca Colour Genetics: Mendel Meets Molecular

    Over the past seven years the team at the Alpaca Molecular Research group at Curtin University has been researching the inheritance patterns and molecular causes of colour in alpacas. Using a combination of Mendelian genetics principles, molecular genetic techniques, objective chemical analysis of the fibre and observation of skin and nail colour we have been able to arrive at a model that, we think, describes most of the colour variation in alpacas. The current nomenclature for alpaca colours contributes to the confusion. One person's fawn is another's light brown and one person's mid brown is another's red brown. We therefore propose a new set of names for base colour varieties that reflects the genetic basis of the colour. more »
  • Characterisation of the Melanocortin-1 Receptor Gene in Alpaca and Identification of Possible Markers Associated with Phenotypic Variations in Colour

    The aim of this study was to determine if any correlation exists between melanocortin-1 receptor (MC1R) polymorphisms and skin and fibre colour in alpacas. Primers capable of amplifying the entire alpaca MC1R gene were designed from a comparative alignment of Bos taurus and Mus musculus MC1R gene sequences. The complete MC1R gene of 41 alpacas exhibiting a range of fibre colours, and which were sourced from farms across Australia, was sequenced from PCR products. Twenty-one single nucleotide polymorphisms were identified within MC1R. Two of these polymorphisms (A82G and C901T) have the potential to reduce eumelanin production by disrupting the activity of MC1R. No agreement was observed between fibre colour alone and MC1R genotype in the 41 animals in this study. However, when the animals were assigned to groups based on the presence or absence of eumelanin in their fibre and skin, only animals that had at least one allele with the A82/C901 combination expressed eumelanin. We propose that A82/C901 is the wild-type dominant ‘E’ MC1R allele, while alpacas with either G82/T901 or G82/Y901 are homozygous for the recessive ‘e’ MC1R allele and are therefore unable to produce eumelanin. more »
  • Gene Expression Levels of Alpaca Tyrosinase Gene Family in Individuals of Different Colors

    Melanin plays important roles in the formation of animal hair color, the members of TYR gene family participate in the synthesis of melanin. For exploring the relationship between gene expression of alpaca TYR gene family and alpaca's coat color, the relative expression quantity of TYR,TRP1,TRP2 in alpaca of different colors were analyzed by using real-time quantitative PCR in this research. Results showed that the relative expression quantity of TYR,TRP1,TRP2 in Brown alpaca respectively were 13.669,3.417,8.593 times than that in White alpaca, all results were corrected by the household gene. The findings indicated that gene expression level of TYR gene family in Brown alpaca were higher than that in White alpaca, and the gene expression level of TYR gene family were related with phenotype of alpacas' coat color. more »
  • Gene Expression Profile in White Alpaca (Vicugna pacos) Skin

    A cDNA library from white alpaca (Vicugna pacos) skin was constructed using SMART technology to investigate the global gene expression profile in alpaca skin and identify genes associated with physiology of alpaca skin and pigmentation. A total of 5359 high-quality EST (expressed sequence tag) sequences were generated by sequencing random cDNA clones from the library. Clustering analysis of sequences revealed a total of 3504 unique sequences including 739 contigs (assembled from 2594 ESTs) and 2765 singletons. BLAST analysis against GenBank nr database resulted in 1287 significant hits (E-value < 10−10), of which 863 were annotated through gene ontology analysis. Transcripts for genes related to fleece quality, growth and coat color (e.g. collagen types I and III, troponin C2 and secreted protein acidic and rich in cysteine) were abundantly present in the library. Other genes, such as keratin family genes known to be involved in melanosome protein production, were also identified in the library. Members (KRT10, 14 and 15) of this gene family are evolutionarily conserved as revealed by a cross-species comparative analysis. This collection of ESTs provides a valuable resource for future research to understand the network of gene expression linked to physiology of alpaca skin and development of pigmentation. more »
  • Harlequin Appaloosa Alpaca Genetics

    For many breeders, the key to consistent Harlequin Appaloosa alpaca color production has been a closely guarded secret. Because of the rarity, and increasing popularity, of this coloring, many breeders feel that this secrecy is critical to protect the gene's value. Their logic is certainly not invalid. I have seen this scenario played out in many, many animal industries throughout my lifetime, and I can attest that if a color is rare and valuable, there will be breeders out there who will seek to cash in on that popularity. These breeders will produce color for the sake of color, and will flood the market, thus eliminating the added “rarity factor” value. This is unfortunate, but the fact is that it is also inevitable. Serious, committed Harlequin Appaloosa breeders need to look beyond the “rarity factor” and focus on the future, which is quality. In order to produce quality Harlequin Appaloosas, however, we must first understand how to consistently produce Harlequin Appaloosas, so that we can focus on the quality and not the color. more »
  • Horse Color Genetics

    It is easy to understand horse color genetics at a basic level, since the basic coat colors of black, bay, brown and chestnut (including sorrel) are controlled by relatively few genes and not radically affected by the environment. On this horse color genetics page you will find a discussion of these genes and their affects on the phenotype (external appearance) of various colors and shades of horse. more »
  • Identification and Characterization of microRNAs in White and Brown Alpaca Skin

    MicroRNAs (miRNAs) are small, non-coding 21–25 nt RNA molecules that play an important role in regulating gene expression. Little is known about the expression profiles and functions of miRNAs in skin and their role in pigmentation. Alpacas have more than 22 natural coat colors, more than any other fiber producing species. To better understand the role of miRNAs in control of coat color we performed a comprehensive analysis of miRNA expression profiles in skin of white versus brown alpacas. more »
  • Inheritance of White Colour in Alpacas: Identifying the Genes Involved

    This RIRDC report describes the research conducted as part of the alpaca colour genetics project to identify the genes involved in the inheritance of white colour in alpacas. Three approaches were used (Mendelian, physical and genetic) in an attempt to unravel the mystery surrounding colour inheritance in alpacas. This project has successfully identified key mutations in genes that lead to differences in fibre colour in alpacas. Other genes, which play a role in colour variation in other species, were cleared of involvement in colour variation in alpacas. Through extensive observational analysis a model for Mendelian inheritance of the major colours was developed. In combination, these findings provide breeders with information that allows them to make informed colour breeding choices. more »
  • Inheritance of white, black and brown coat colours in alpaca (Vicuna pacos L.)

    An experimental trial of the segregation of white vs. pigmented and black vs. brown colours in alpacas was conducted at the Peruvian INIA Quimsachata Experimental Station. One hundred and forty five offspring were born from the following matings: 4 white sires × 36 white dams, 4 white sires × 39 pigmented dams, and 9 pigmented sires × 70 pigmented dams. Among these last matings were, 4 black sires × 25 black dams, 2 black sires × 20 brown dams, and 3 brown sires × 25 brown dams. Statistical tests validate that the inheritance of white is due to a single gene which is dominant over pigmentation, without any modifying effect and independent of segregation of black and brown patterns. However, the evidence does not support a simple dominant inheritance of the black vs. brown. more »
  • Nitric Oxide Enhances the Sensitivity of Alpaca Melanocytes to Respond to α-Melanocyte-Stimulating Hormone by Up-Regulating Melanocortin-1 Receptor

    Nitric oxide (NO) and α-melanocyte-stimulating hormone (α-MSH) have been correlated with the synthesis of melanin. The NO-dependent signaling of cellular response to activate the hypothalamopituitary proopiomelanocortin system, thereby enhances the hypophysial secretion of α-MSH to stimulate α-MSH-receptor responsive cells. In this study we investigated whether an NO-induced pathway can enhance the ability of the melanocyte to respond to α-MSH on melanogenesis in alpaca skin melanocytes in vitro. It is important for us to know how to enhance the coat color of alpaca. We set up three groups for experiments using the third passage number of alpaca melanocytes: the control cultures were allowed a total of 5 days growth; the UV group cultures like the control group but the melanocytes were then irradiated everyday (once) with 312 mJ/cm2 of UVB; the UV + L-NAME group is the same as group UV but has the addition of 300 μM L-NAME (every 6 h). To determine the inhibited effect of NO produce, NO produces were measured. To determine the effect of the NO to the key protein and gene of α-MSH pathway on melanogenesis, the key gene and protein of the α-MSH pathway were measured by quantitative real-time PCR and Western immunoblotting. The results provide exciting new evidence that NO can enhance α-MSH pathway in alpaca skin melanocytes by elevated MC1R. And we suggest that the NO pathway may more rapidly cause the synthesis of melanin in alpaca skin under UV, which at that time elevates the expression of MC1R and stimulates the keratinocytes to secrete α-MSH to enhance the α-MSH pathway on melanogenesis. This process will be of considerable interest in future studies. more »
  • No Such Thing as a Dominant White?

    If any of the assertions below contradict what you believe about alpaca base coat color genetics, it’s definitely worth reading this blog post and continuing on to a very friendly, fun-loving statistical analysis that is available in our website’s library! 1. First, all white alpacas can produce color when they are bred to it. There is no such thing as a homozygous dominant white animal. In fact, a pink-skinned white is in some ways as recessive a creature as a true black. 2. What’s more, many fawns are not just “dilute” but carry a white base coat color allele, which acts to dilute a brown allele in the production of the phenotypic coat color. You can actually breed two fawns together and get a homozygous white. 3. White breeders, no need to rely on those pure-white pedigrees to make sure you don’t produce fawns and browns. Turns out a brown allele can’t really hide itself well phenotypically. 4. Color breeders, to introduce white genetics into a color breeding program with lower odds of producing white offspring, breed that white animal to brown. The darker, the better. more »
  • Pigmentation in Alpaca Fleece Color: Red or Black?

    Alpaca breeders, unlike those of other species in a not-so-distant past, will not have to resort to numerous and time consuming test breedings to establish inheritance of color genes. We will soon know... with the competent help of one very busy, very knowledgeable woman and a few drops of blood... exactly why that alpaca is red or black. Imagine that! more »
  • Skin Transcriptome Profiles Associated with Coat Color in Sheep

    Previous molecular genetic studies of physiology and pigmentation of sheep skin have focused primarily on a limited number of genes and proteins. To identify additional genes that may play important roles in coat color regulation, Illumina sequencing technology was used to catalog global gene expression profiles in skin of sheep with white versus black coat color. more »
  • Suris With Spots

    Every now and then, on an alpaca farm somewhere in Australia, the day brings an unexpected arrival, a new suri cria ... with spots! When that cria has two solid coloured parents, it is more of a surprise. more »
  • The Alpaca Agouti Gene: Genomic Locus, Transcripts and Causative Mutations of Eumelanic and Pheomelanic Coat Color

    The agouti gene encodes the agouti signaling protein (ASIP) which regulates pheomelanin and eumelanin synthesis in mammals. To investigate the role of agouti in coat color variation of alpaca, we characterized the agouti gene and identified three mutations potentially involved with the determinism of eumelanic and pheomelanic phenotypes. The exon-4 hosts the mutations g.3836C>T, g.3896G>A and g.3866_3923del57. Further analysis of these mutations revealed two genotypes for black animals. The reverse transcription analysis of mRNA purified from skin biopsies of alpaca revealed the presence of three transcripts with different 5′ untranslated regions (UTRs) and color specific expression. The white specific transcript, possibly originating from a duplication event (intra-chromosomal recombination) of the agouti gene is characterise by a 5′UTR containing 142 bp of the NCOA6 gene sequence. Furthermore, the relative level expression analysis of mRNA demonstrates that the agouti gene has up-regulated expression in white skin, suggesting a pleiotropic effect of agouti in the white phenotype. Our findings refine the structure of the agouti locus and transcripts and provide additional information in order to understand the role of agouti in the pigmentation of alpaca. more »
  • The Genetic Inheritance of the Blue-Eyed White Phenotype in Alpacas (Vicugna pacos)

    White-spotting patterns in mammals can be caused by mutations in the gene KIT, whose protein is necessary for the normal migration and survival of melanocytes from the neural crest. The alpaca (Vicugna pacos) blue-eyed white (BEW) phenotype is characterized by 2 blue eyes and a solid white coat over the whole body. Breeders hypothesize that the BEW phenotype in alpacas is caused by the combination of the gene causing gray fleece and a white-spotting gene. We performed an association study using KIT flanking and intragenic markers with 40 unrelated alpacas, of which 17 were BEW. Two microsatellite alleles at KIT-related markers were significantly associated (P < 0.0001) with the BEW phenotype (bew1 and bew2). In a larger cohort of 171 related individuals, we identify an abundance of an allele (bew1) in gray animals and the occurrence of bew2 homozygotes that are solid white with pigmented eyes. Association tests accounting for population structure and familial relatedness are consistent with a proposed model where these alleles are in linkage disequilibrium with a mutation or mutations that contribute to the BEW phenotype and to individual differences in fleece color. more »
  • The Genetics of Gray Alpacas

    With all the discussion about gray alpacas taking place online on the various alpaca chat forums, I thought it would be worthwhile to reiterate my current understanding of the different kinds of grays and how their phenotypes are passed on. I would suggest that there are at least four kinds of alpacas that are called grays. more »