The ASIP gene in the llama (Lama glama): Alternative transcripts, expression and relation with color phenotypes.

The Agouti gene (ASIP) is one of the most important genes for coat color determination in mammals. It has a complex structure with several promoters and alternative non-coding first exons that are transcribed into mRNAs with different 5'UTR. These mRNA isoforms regulate the temporal and spatial expression of the gene, producing diverse pigmentation patterns. Here, we studied ASIP transcriptional variants and their expression in the skin of llamas with different coat color phenotypes. We also described the ASIP locus, including promoter usage and the splicing events that originate each transcript variant. Using 5'RACE-PCR we isolated seven ASIP transcripts with alternative 5'UTR, where exons 1A, 1A', 1C, 1D, and a novel non-coding exon 1A" were identified. Additionally, new alternative spliced forms were found. The diversity of ASIP 5'UTRs is originated by a complex pattern of alternative promoter usage, multiple transcription start sites and splicing events that include exon skipping and alternative 3' splicing site selection. We found that ASIP was highly expressed in llamas with white and brown phenotypes while black animals presented very low expression. The main responsible for this difference was a fusion transcript between ASIP and NCOA6 genes, which was present in the skin of white and brown llamas but not in the black ones. The rest of ASIP transcripts presented very low expression in the skin, indicating that the main regulation point for ASIP gene expression is at the transcriptional level. Nevertheless, the characteristics of the 5'UTRs sequences suggest that alternative transcripts could be regulated differently at the protein synthesis level.

Genetics of fibre production and fleece characteristics in small ruminants, Angora rabbit and South American camelids.

This paper reviews genetics of fibre production and fleece characteristics in small ruminants, Angora rabbit and South American camelids with a special distinction between single-coated (SC) and double-coated (DC) species. Considering the biology of fibre production, there are variations in coat composition and structure, fibre growth pattern and fibre structure and quality between these two main kinds of fibre-producing animals. In SC species, all fibres are nearly similar in dimensions and are produced from individual follicles that have a very long period, essentially permanent, of active growth without a synchronous phase of rest between follicles. In contrast, in DC species the fleece comprises a coarse outer coat and a fine inner coat with variations of coat composition and structure, and fibre growth pattern according to the season with a well-defined duration of fibre growth. Genetic basis of hair growth pattern, coat composition and fibre structure are different between species. In small ruminants, these coat characters are additive and because of several genes whereas in rabbit, several autosomal recessive genes determine fibre growth, coat composition and structure. In alpaca, the fleece type (Suri or Huacaya) is determined by a single dominant gene. This paper also reviews genetic parameters of fibre production traits in Angora goat, Angora rabbit and alpaca in which many aspects of the genetic basis of fibre production are analogous. There are many traits controlling both fibre quality and fibre quantity, and most of these traits tend to be moderately to strongly inherited so that a rapid genetic progress in any traits is possible and indeed has been achieved. However, there are differences in breeding programmes. In DC Angora rabbit, selection for one single trait, the easy measurable total fleece weight has general beneficial effects on fleece quality. However, because of antagonistic relations between qualitative and quantitative traits in SC species, achieving this goal requires a multi-trait selection index approach. Gene mapping studies have recently identified several putative quantitative trait loci and major genes affecting fibre and fleece characteristics in sheep, goat and rabbit are reviewed. The whole genome sequence of sheep and rabbit will be available in the near future and the use of high-density single nucleotide polymorphism chip will allow fine mapping and dissection of the genetic basis of many production traits including fibre production and fleece characteristics. The application of these techniques will thus contribute to improving the efficiency, profitability and sustainability of small ruminant and rabbit fibre production.

Plumage colour mutations and melanins in the feathers of the Japanese quail: a first comparison.

The absorbance of melanin content from dorsal feathers was compared between wild-type Japanese quail and nine other quail plumage colours determined by single mutations in one of seven genes: extended brown (MC1R), yellow (ASIP), silver (MITF), lavender (MLPH), roux (TYRP1), imperfect albinism (SLC45A2) and rusty. As compared with wild-type quail, all mutations but extended brown decreased total melanins. The largest decrease was observed in quail with one of the dilution mutations at TYRP1, MLPH or SLCA45A2. No difference in eumelanins was found between the 10 plumage colours. Despite visible colour differences, homozygous and heterozygous mutants at MITF, or the two imperfect albino (white) and cinnamon (pale yellow) alleles at SLC45A2, could not be differentiated on the basis of melanins. In contrast, the two white phenotypes caused by mutations at MITF and SLC45A2, or the two reddish plumage colours caused by the roux and rusty non-allelic mutations had different total melanin contents. The results showed that rusty was not likely to be a dilution mutation.

Tenderness evaluation and mineral levels of llama (Lama glama) and alpaca (Lama pacos) meat.

Tenderness and mineral levels were determined in the Longissimus thoracis taken from 20 llama and 30 alpaca males reared in Peru and slaughtered at 25 months of age. Mineral contents were determined using an inductively coupled plasma emission spectrometer. Tenderness evaluation was determined two and seven days post slaughter using a Warner-Bratzler shear force device. Potassium is the mineral with the highest content, with a significant difference (P<0.05) between the two species of camelids. The other mineral contents were, in decreasing order, phosphorus, sodium, magnesium and calcium, in addition to smaller percentages of zinc and iron. Shear force values determined seven days post slaughter were significantly (P<0.01) lower in both the species compared with the results obtained two days post slaughter.

Meat fatty acid composition of llama (Lama glama) reared in the Andean highlands.

This study reports the results of the chemical analysis of the Longissimus thoracis and lumborum taken from 20 llama males, reared in the Andean highlands. The animals were slaughtered at 25 months and had a mean final body weight of 63kg. Llama meat shows a low fat (3.51%) and cholesterol content (56.29mg/100g). The fatty acid composition in llama meat contains 50.34% saturated fatty acids, 42.48% monounsaturated fatty acids and 7.18% polyunsaturated fatty acids. Llama meat appears to be a healthy alternative red meat choice.

Meat and carcass quality from Peruvian llama (Lama glama) and alpaca (Lama pacos).

An experiment based on 20 llama males and 40 alpaca males reared in Peru has been carried out with the aim to evaluate the live growth performances, carcass quality, the nutritional characteristics of meat from animals slaughtered at 25 months of age, and to determine the physical and chemical parameters of meat obtained from these animals. The live body weights registered during the 25 months of the experiment were significantly lower in alpaca compared with llama. In llama carcasses were significantly higher both warm and cold carcass weight (P<0.001) but dressing percentage was higher in alpacas (P<0.01). The glycolityc fine-course was very similar both in llama and in alpaca muscle Longissimus Thoracis et Lumborum. Chemical composition of muscle Longissimus Thoracis et Lumborum taken from llama and alpaca carcasses was significantly different (P<0.01) in ash content; cholesterol content was significantly higher (P<0.001) in llama meat compared with alpaca.

Tenderization of wether lambs meat through pre-rigor infusion of calcium ions.

A study involving 36 wether lamb carcasses was conducted in order to evaluate the effects of 0.3 M CaCl(2) injection on final tenderness in muscle Longissimus thoracis et lumborum. Injection of wether lamb carcasses with CaCl(2) accelerated the post mortem tenderization process. Both control and distilled water injected animals had similar Ca(2+)-dependent proteases (µ-calpain and m-calpain) and their inhibitor (calpastatin) activities, whereas these were all significantly decreased in CaCl(2) injected animals. The effect of CaCl(2) injection on tenderness was recorded by measuring shear force values 2 and 6 days post mortem. Tenderness was significantly improved by CaCl(2) injection at both at 2 and 6 days post mortem. It was concluded that activation of µ-calpain and m-calpain was responsible for the observed post mortem proteolysis and tenderization.

Chemical and electron microscopic studies of cattle (Bos taurus) with four types of phenotypic pigmentation.

The biological behavior of the pigmentary phenotypes of four breeds of cattle has been analysed: the black pigmentation of Holstein Friesian; the red pigmentation of Limousin; the dilution in Charolais; and the postnatal disappearance of red pigmentation in Chianina. The analytic techniques included the characterization of melanins by high-performance liquid chromatography, the examination of follicular melanocytes by light microscopy, and the examination of melanosomes by electron microscopy. The black phenotype was very strongly eumelanogenic. The red phenotype in Limousin is polymorphic: individual follicular melanocytes contain both mature eumelanosomes and pheomelanosomes. Charolais and Chianina cattle exhibited a dramatic reduction in melanogenic activity, which was characterized by the almost exclusive presence of prephaoemelanosomes in Charolais and of immature premelanosomes in Chianina. In the dilute Charolais phenotype, the density of distribution of follicular melanocytes also seemed to be reduced. The genes that are responsible for these four phenotypes seem to act on the maturation, differentiation, and density of distribution of the melanosomes.

Estimating erosion of phenotypic variation in a French goat population.

A survey was made on a sample of 45 flocks of the goat population in Provence France in 1982. The sample included 56 male goats and 757 breeding females within a 30 km radius of the town of Forcalquier (Alpes-de-Haute-Provence). The visible phenotypic profile was established for the following characters: ear length, ear curling, ear erectness, presence of horns, type of horns, presence of wattles, presence of beard, length of hair, hair coat pigmentation pattern, type of eumelanin in hair, pigment alteration of hair, and white spotting (36 different phenotypes). The visible genic profile is based on 23 various alleles at eight loci. This high degree of genetic variability comes from the traditional local population that is in the process of being upgraded to standardized breeds such as Saanen, Rove and, mainly, Chamois Alpine (95 percent of upgraded flocks). The average coefficient of phenotypic erosion ep had a value of 32 percent among the breeding females in 1982. At the present rate of upgrading the estimate is 90 percent for the male and 85 percent for the female coefficient of genotypic erosion eg by the year 2002. A small nucleus of purely traditional Provence goat (5 percent of the present size of the population: about 1500 goats for the PACA (Provence-Alpes-Côte d'Azur region) will probably have disappeared by that time. Phenotypic and genic profiles of this Provence population have been compared to the profiles of other traditional goat populations in Central Asia, Norway, Sardinia, and Corsica. The available data show profiles that are very similar.(ABSTRACT TRUNCATED AT 250 WORDS)