Transient Ectopic Overexpression of Agouti-Signalling

While flatfish in the wild exhibit a pronounced countershading of the dorso-ventral pigment pattern, malpigmentation is commonly observed in reared animals. In fish, the dorso-ventral pigment polarity is achieved because a melanization inhibition factor (MIF) inhibits melanoblast differentiation and encourages iridophore proliferation in the ventrum. A previous work of our group suggested that asip1 is the uncharacterized MIF concerned. In order to further support this hypothesis, we have characterized asip1 mRNAs in both turbot and sole and used deduced peptide alignments to analyze the evolutionary history of the agouti-family of peptides. The putative asip precursors have the characteristics of a secreted protein, displaying a putative hydrophobic signal. Processing of the potential signal peptide produces mature proteins that include an N-terminal region, a basic central domain with a high proportion of lysine residues as well as a proline-rich region that immediately precedes the C-terminal poly-cysteine domain. The expression of asip1 mRNA in the ventral area was significantly higher than in the dorsal region. Similarly, the expression of asip1 within the unpigmented patches in the dorsal skin of pseudoalbino fish was higher than in the pigmented dorsal regions but similar to those levels observed in the ventral skin. In addition, the injection/electroporation of asip1 capped mRNA in both species induced long term dorsal skin paling, suggesting the inhibition of the melanogenic pathways. The data suggest that fish asip1 is involved in the dorsalventral pigment patterning in adult fish, where it induces the regulatory asymmetry involved in precursor differentiation into mature chromatophore. Adult dorsal pseudoalbinism seems to be the consequence of the expression of normal developmental pathways in an inaccurate position that results in unbalanced asip1 production levels. This, in turn, generates a ventral-like differentiation environment in dorsal regions.Publicado

Microsatellite mapping of QTL affecting growth, feed consumption, egg production, tonic immobility and body temperature of Japanese quail

BACKGROUND: The Japanese quail (Coturnix japonica) is both an animal model in biology and a commercial bird for egg and meat production. Modern research developments with this bird, however, have been slowed down by the limited information that is available on the genetics of the Japanese quail. Recently, quail genetic maps with microsatellites and AFLP have been produced which open the way to comparative works with the chicken (Gallus gallus), and to QTL detection for a variety of traits. The purpose of this work was to detect for the first time QTL for commercial traits and for more basic characters in an F2 experiment with 434 female quail, and to compare the nature and the position of the detected QTL with those from the first chicken genome scans carried out during the last few years. RESULTS: Genome-wide significant or suggestive QTL were found for clutch length, body weight and feed intake on CJA01, age at first egg and egg number on CJA06, and eggshell weight and residual feed intake on CJA20, with possible pleiotropy for the QTL affecting body weight and feed intake, and egg number and age at first egg. A suggestive QTL was found for tonic immobility on CJA01, and chromosome-wide significant QTL for body temperature were detected on CJA01 and CJA03. Other chromosome-wide significant QTL were found on CJA02, CJA05, CJA09 and CJA14. Parent-of-origin effects were found for QTL for body weight and feed intake on CJA01. CONCLUSION: Despite its limited length, the first quail microsatellite map was useful to detect new QTL for rarely reported traits, like residual feed intake, and to help establish some correspondence between the QTL for feed intake, body weight and tonic immobility detected in the present work and those reported on GGA01 in the chicken. Further comparative work is now possible in order to better estimate and understand the genetic similarities and differences of these two Phasianidae species

Mutation in ASIP and MC1R that effects the coat colour in Gotland sheep

Gotlandsfår har avlats för en jämn och klar ull. Ullfärgen varierar mellan vit till svart, men marknaden önskar ull mellan ljusgrå och mörkgrå. Genom studier på gener associerade med ullfärgen blir det lättare att förstå deras roll vid pigmenteringen. Studien gjordes på 88 Gotlandsfår samt 41 avkommor och deras föräldradjur där en tidigare känd mutation i ASIP [recessiv svart allel, g.100_105del (D5)] undersöktes för att se om mutationen har någon påverkan på nyansen av ullfärgen. Resultatet visade inget samband mellan ullfärgens nyans och D5 deletionen hos Gotlandsfår. Studien visade även att det inte fanns något tydligt samband mellan föräldradjurens och avkommans ullfärg, samt avkommans genotyp. 56,8 % av Gotlandsfåren hade den vanliga genotypen med avsaknad av D5, NN, den kunde ses bland alla ullfärger förutom svart. Genotypen ND, som beror på mutationen i ASIP, kunde även den ses hos samtliga ullfärger.The Gotlands sheep have been breed for a consistent and clear coat. The coat colour varies between white and black, but the market prefer a coat between light grey and dark grey. By studying the genes associated with coat colour it will be easier to understand the roll it has in pigmentation. The study was made on 88 Gotland sheep and 41 offspring along with their parents where a previously known mutation in ASIP [recessive black allele, g.100_105del (D5)] where investigated to see if the mutation has any influence on the coat colour. The result showed that there isn´t a significant relationship between the coat colour and whether the Gotland sheep had the D5 mutation or not. The study also showed that there is no significant relationship between the offspring and the parents coat colour, and the offspring’s genotype. 56,8 % of the Gotland sheep had the regular genotype with the absent of D5, NN, it could be seen in all colours except black. The ND genotype, which is due to the mutation in ASIP, could also be seen in all colours

Novel hypophysiotropic AgRP2 neurons and pineal cells revealed by BAC transgenesis in zebrafish

The neuropeptide agouti-related protein (AgRP) is expressed in the arcuate nucleus of the mammalian hypothalamus and plays a key role in regulating food consumption and energy homeostasis. Fish express two agrp genes in the brain: agrp1, considered functionally homologous with the mammalian AgRP, and agrp2. The role of agrp2 and its relationship to agrp1 are not fully understood. Utilizing BAC transgenesis, we generated transgenic zebrafish in which agrp1- and agrp2-expressing cells can be visualized and manipulated. By characterizing these transgenic lines, we showed that agrp1-expressing neurons are located in the ventral periventricular hypothalamus (the equivalent of the mammalian arcuate nucleus), projecting throughout the hypothalamus and towards the preoptic area. The agrp2 gene was expressed in the pineal gland in a previously uncharacterized subgroup of cells. Additionally, agrp2 was expressed in a small group of neurons in the preoptic area that project directly towards the pituitary and form an interface with the pituitary vasculature, suggesting that preoptic AgRP2 neurons are hypophysiotropic. We showed that direct synaptic connection can exist between AgRP1 and AgRP2 neurons in the hypothalamus, suggesting communication and coordination between AgRP1 and AgRP2 neurons and, therefore, probably also between the processes they regulate

A GENETIC STUDY OF SUSCEPTIBILITY TO EXPERIMENTAL TUBERCULOSIS IN MICE INFECTED WITH MAMMALIAN TUBERCLE BACILLI

A study has been made of the genetic aspects of the difference between two inbred strains of mice (C57B1/6 and Swiss) in response to experimental infection with mammalian tubercle bacilli. Males and females, 4 to 6 weeks of age were inoculated intravenously with 0.2 ml of a 1/50 culture dilution of Mycobacterium tuberculosis var. bovis (Vallée strain) grown in tween albumin medium. Mean survival time for C57B1 animals was 28.1 ± 0.6 days and for Swiss, 55.3 ± 0.6 days postinfection. The characteristic survival time of the two strains was reversed in mice receiving a smaller infective dose. The age of mice at the time of inoculation also affected the results of infection: both C57B1 and Swiss, inoculated at 12 months of age, died at the same rate, but when inoculated at older ages, C57B1 survived slightly longer. Bacteriologic studies demonstrated that there was no significant difference between the two mouse strains with regard to the numbers of viable units of tubercle bacilli recovered from various organs during the 2 week period following infection with a 10–3 culture dilution of Vallée. Moreover, the standard infective inoculum (1/50 culture dilution) did not activate corynebacterial pseudotuberculosis in C57B1 mice, a strain known to be latently infected with Corynebacterium kutscheri, rapid multiplication of tubercle bacilli occurred, but no corynebacteria were recovered. When C57B1 and Swiss strains were crossed, survival tests after infection with the standard inoculum demonstrated that mice of the F1 generation were more resistant than either parent. Whether the overdominance was due to a new combination of parental genes for resistance or to heterosis was not determined. The increased litter size of the F1 mice, an evidence of increased vigor, supports the view that heterosis was involved. In backcrosses to the resistant strain (Swiss), survival time gradually became stabilized at approximately the parental level. In the 1st backcross to the susceptible strain (C57B1), survival times fell into two classes indicating segregation of genes, with perhaps dominance of genes from the Swiss. After repeated backcrosses to C57B1, mice of the 4th backcross generation had a survival time essentially the same as that of the original parental strain. On the basis of having obtained progeny characterized by the original parental susceptibilities after genetic tendencies had been intermingled by crossbreeding, it was concluded that hereditary factors influenced the response of mice to experimental infection with M. tuberculosis. The number of genes was not determined

Dog Coat Colour Genetics: A Review

Canis lupus familiaris is one of the most beloved pet species with hundreds of world-wide recognized breeds, which can be differentiated from each other by specific morphological, behavioral and adoptive traits. Morphological characteristics of dog breeds get more attention which can be defined mostly by coat color and its texture, and considered to be incredibly lucrative traits in this valued species. Although the genetic foundation of coat color has been well stated in the literature, but still very little is known about the growth pattern, hair length and curly coat trait genes. Skin pigmentation is determined by eumelanin and pheomelanin switching phenomenon which is under the control of Melanocortin 1 Receptor and Agouti Signaling Protein genes. Genetic variations in the genes involved in pigmentation pathway provide basic understanding of melanocortin physiology and evolutionary adaptation of this trait. So in this review, we highlighted, gathered and comprehend the genetic mutations, associated and likely to be associated variants in the genes involved in the coat color and texture trait along with their phenotypes. Moreover, genetic diversity of other associated genes were also pointed out to understand this phenomena in detail along with their genotypes for better understanding the expression and mode of inheritance of this trait for describing dog breeds with more accuracy.Keywords: Dog breeds; Dog color variants; Dog texture genetics; Dog breed differentiation