Quantitative Trait Loci (QTLs) mapping for growth traits in the mouse: A review

The attainment of a specific mature body size is one of the most fundamental differences among species of mammals. Moreover, body size seems to be the central factor underlying differences in traits such as growth rate, energy metabolism and body composition. An important proportion of this variability is of genetic origin. The goal of the genetic analysis of animal growth is to understand its "genetic architecture", that is the number and position of loci affecting the trait, the magnitude of their effects, allele frequencies and types of gene action. In this review, the different strategies developed to identify and characterize genes involved in the regulation of growth in the mouse are described, with emphasis on the methods developed to map loci contributing to the regulation of quantitative traits (QTLs)

Analysis of a polymorphism in the DGAT1 gene in 14 cattle breeds through PCR-SSCP methods

The diacylglycerol O-acyltransferase (DGAT1) is a microsomal enzyme that catalyzes the final step of triglyceride synthesis. Recent work have evidenced a significant association between lysine at amino acid position 232 with elevated milk fat content, while an alanine at this position is associated with lowered milk fat content. The aim of the present work was to develop a simple and inexpensive PCR-SSCP assay in order to discriminate the CG/AA alleles in exon 8 of the DGAT1 gene. In addition, this method was used to analyze the polymorphism of the DGAT1 through PCR-SSCP methods in 14 populations of cattle from Argentine, Bolivia and Uruguay. The PCR primers were designed from GenBank reported sequences. In this study, we found three PCR-SSCP variants, which were denominated from "A" to "C". However, DNA sequencing analysis showed that "A" variant corresponded with the A allele, while both "B" and "C" observed pattern have the motif AA at positions 10,433-10,434 (K allele), being two alternative conformations of the same DNA sequence. Both variants were detected within each breed with the exception of Hereford, and the heterozygosity varied between 0.000 and 0.524. The gene frequency analysis evidenced significant differences among the studied breeds (FST = 0.325, p = 0.000). European Bos taurus breeds, with the exception of Jersey breed, showed the lowest frequency of the K allele, while highest K allele frequencies were harboured by Bos indicus type cattle. In addition, unselected South American Creole cattle breeds and the synthetic Brangus breed had intermediate allele frequencies.Fil: Ripoli, María Verónica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico CONICET- La Plata. Instituto de Genética Veterinaria "Ing. Fernando Noel Dulout". Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias. Instituto de Genética Veterinaria; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias. Centro de Investigaciones en Genética Básica y Aplicada; ArgentinaFil: Corva, Pablo Marcelo. Universidad Nacional de Mar del Plata, Facultad de Ciencias Agrarias, Departamento de Producción Animal, Balcarce; ArgentinaFil: Giovambattista, Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico CONICET- La Plata. Instituto de Genética Veterinaria "Ing. Fernando Noel Dulout". Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias. Instituto de Genética Veterinaria; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias. Centro de Investigaciones en Genética Básica y Aplicada; Argentin

Genome-wide isolation of growth and obesity QTL using mouse speed congenic strains

BACKGROUND: High growth (hg) modifier and background independent quantitative trait loci (QTL) affecting growth, adiposity and carcass composition were previously identified on mouse chromosomes (MMU) 1, 2, 5, 8, 9, 11 and 17. To confirm and further characterize each QTL, two panels of speed congenic strains were developed by introgressing CAST/EiJ (CAST) QTL alleles onto either mutant C57Bl/6J-hg/hg (HG) or wild type C57Bl/6J (B6) genetic backgrounds. RESULTS: The first speed congenic panel was developed by introgressing four overlapping donor regions spanning MMU2 in its entirety onto both HG and B6 backgrounds, for a total of eight strains. Phenotypic characterization of the MMU2 panel confirmed the segregation of multiple growth and obesity QTL and strongly suggested that a subset of these loci modify the effects of the hg deletion. The second panel consisted of individual donor regions on an HG background for each QTL on MMU1, 5, 8, 9, 11 and 17. Of the six developed strains, five were successfully characterized and displayed significant differences in growth and/or obesity as compared to controls. All five displayed phenotypes similar to those originally attributed to each QTL, however, novel phenotypes were unmasked in several of the strains including sex-specific effects. CONCLUSION: The speed congenic strains developed herein constitute an invaluable genomic resource and provide the foundation to identify the specific nature of genetic variation influencing growth and obesity

Análisis de secuencias genómicas sugieren que el gen de la prodinorfina está bajo selección positiva en bovinos

Dynorphin A is an endogenous opioid peptide that is part of the KNDy system in the hypothalamus of mammals. This peptide acts as an inhibitor of the GnRH pulse generation, thus regulating the onset of puberty and reproductive cycles. The PDYN gene encodes the propeptide Prodynorphin, the precursor of Dynorphin A. Despite its physiological relevance, PDYN has not emerged as a candidate gene associated with puberty in genomic association studies conducted in cattle. The present work aimed to search for signatures of selection on the PDYN gene among cattle breeds. To this, the whole genome sequences from 57 samples of ten cattle breeds were used. The samples were grouped based on breed selection history and their productive differences, particularly in terms of sexual precocity. The population structure was analyzed using Principal Component Analyses. To evidence recent selection processes, neutrality tests, such as Tajima’s D and Fu & Li’s F* and D* were performed in defined functional regions of PDYN. The putative promoter of PDYN showed a population structure that is in agreement with the criteria considered to make the groups. In that region, neutrality tests were consistently negative and resulted in statistically significant for the dairy breeds. Also, these breeds exhibited less variability in the haplotype analyses than the others. The results presented here suggest that regulatory regions of PDYN could be under positive selection, particularly in dairy breeds.Dinorfina A es un péptido opioide endógeno que forma parte del sistema KNDy en el hipotálamo de mamíferos. Este péptido actúa como inhibidor de la generación de los pulsos de GnRH, regulando así el inicio de la pubertad y los ciclos reproductivos. El gen PDYN codifica el propéptido Prodinorfina, precursor de Dinorfina A. A pesar de su relevancia fisiológica, PDYN no ha surgido como gen candidato asociado a pubertad en estudios de asociación genómicos en bovinos. El presente trabajo tuvo como objetivo buscar huellas de selección en el gen PDYN entre diferentes razas bovinas. Para alcanzarlo se utilizaron secuencias genómicas de 57 muestras de diez razas bovinas. Las muestras fueron agrupadas considerando la historia de selección y las diferencias productivas entre razas, particularmente en términos de precocidad sexual. La estructura poblacional fue analizada usando análisis de componentes principales. Para evidenciar procesos de selección recientes se realizaron pruebas de neutralidad, tales como D de Tajima y F* y D* de Fu & Li, en diferentes regiones funcionales de PDYN. El promotor putativo de PDYN mostró una estructura poblacional que es consistente con los criterios usados para agrupar las razas. En esa región, las pruebas de neutralidad fueron consistentemente negativas y estadísticamente significativas en las razas lecheras. Además, estas razas también exhibieron menor variabilidad en los análisis de haplotipos que las demás razas. Los resultados presentados aquí sugieren que regiones regulatorias de PDYN estarían bajo selección positiva, particularmente en razas bovinas lecherasFil: Suqueli García, María Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; ArgentinaFil: Castellote, Martín Alfredo. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce; ArgentinaFil: Corva, Pablo Marcelo. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentin

Genetic and environmental factors influencing beef tenderness

Tenderness is one of the most important quality attributes of beef. However, it is difficult to predict and its causation is complex. Tenderness is influenced by factors inherent to the animal, such as its genetic constitution, management and feeding, and also by practices employed at slaughter and subsequent handling of the meat. In spite of the large number of factors involved, research results indicate that tenderness can be increased through genetic improvement of animals. In this review the structure of skeletal muscle and its relation to subsequent tenderness of the meat are described. Also discussed are the principal genetic and environmental factors that determine its variability. Emphasis is placed on the role of molecular marker technology in prediction of meat tenderness and in animal improvement

Simulation of marker assisted selection strategies in beef cattle

Marker-assisted selection (MAS) has been presented as a promising tool for animal breeding, but its application in beef cattle is still very limited. The technology is still expensive and the way to combine molecular information with more traditional breeding strategies has not been well defined. In order to evaluate MAS strategies, a simulation study was conducted. A beef cattle herd was simulated, in which selection was practiced to improve weaning weight. Three molecular markers with effect on weaning weight explained 40% of the additive variance. Four strategies were compared: mass selection based on phenotypes, marker-assisted selection, selection with animal model (BLUP) and a combined strategy in which the phenotypes were corrected for the effect of the markers and then analyzed with an animal model. Molecular analysis was performed on a limited number of individuals and genotypes of the rest of the population were inferred by segregation analysis. Marker-based selection was the least effective option. Selection based on animal model and the combined strategy performed better than mass selection. Under the simulated conditions, the combined approach showed a slight advantage over the animal model (3% in years 6-8) that would be of little practical relevance. Still, the feasibility of integrating molecular and quantitative genetic information in a single strategy was confirmed. Further research should evaluate options to optimize both the number of markers and of animals to be genotyped

Feed sorting behavior and performance of Argentinian Creole, Braford and crossbred steers during the growing and fattening phases

Local Latin American cattle breeds are considered highly adapted to grazing systems in harsh environments, but their potential in more intensified beef production systems, particularly when compared to imported breeds, is still a matter of debate. Argentinian Creole (CRA), Braford (BRA) and Creole x Braford (CXB) steers were evaluated in the growing (Experiment 1) and fattening phases (Experiment 2). In Experiment 1, 12 animals from each genetic group were allocated after weaning to four pens and fed a total mixed ration for 57 days. In Experiment 2, six 17-month old steers of each genetic group were allocated each to a single pen and fed a high concentrate diet for 55 days. Several traits associated with animal performance, feed intake and feed sorting were recorded. Experiment 1: CRA had lower daily weight gain than the other two groups (P 19 mm, BRA CRA = CXB, P = 0.06). Experiment 2: CRA had lower initial body weight (P 19 mm, BRACRA y CXB, P=0.06). Experimento 2: el peso vivo inicial de CRA fue más bajo que en BRA y CXB (P<0.01) y la diferencia con BRA también fue significativa al final del experimento (P<0.01). CRA tuvo menor espesor de grasa dorsal (P<0.01). El área inicial y final del ojo de bife fue similar entre grupos en ambos experimentos. La clasificación de las partículas en alimento fue similar entre grupos (P≥0.21). Todos los resultados sugieren que CRA tuvo un desempeño productivo inferior a BRA y CXB en ambos experimentos.Instituto de Investigación Animal del Chaco SemiáridoFil: Della Rosa, María Milagros. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Investigación Animal del Chaco Semiárido; ArgentinaFil: Corva, Pablo Marcelo. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias. Departamento de Producción Animal; ArgentinaFil: Royo, Victoria. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Investigación Animal del Chaco Semiárido; ArgentinaFil: Zimerman, María. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Investigación Animal del Chaco Semiárido; ArgentinaFil: Bottegal, Diego Nicolas. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Investigación Animal del Chaco Semiárido; ArgentinaFil: Nasca, Jose Andres. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Investigación Animal del Chaco Semiárido; Argentin

Diferenciales de selección genética en Holando Argentino

La selección genética en ganado lechero a nivel global ha resultado en aumentos considerables en la productividad. En contraste, la producción de leche en Argentina se ha mantenido estable durante los últimos 20 años, aún cuando otros países con sistemas productivos similares han incrementado significativamente su producción en el mismo periodo. El objetivo de este estudio fue determinar los diferenciales de selección realizados en la población de Holando Argentino bajo el modelo de selección de 4 víasEEA BalcarceFil: Pardo, Alan M. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Balcarce; Argentina.Fil: Corva, Pablo. Unidad Integrada Balcarce. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Balcarce; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina.Fil: Dillon Anabella Unidad Integrada Balcarce. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Balcarce; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina.Fil: Rubio, Natalia. Universidad Nacional del Centro de la Provincia de Buenos Aires, Facultad de Ciencias Veterinarias; Argentina.Fil: Andere, C. Universidad Nacional del Centro de la Provincia de Buenos Aires, Facultad de Ciencias Veterinarias; Argentina.Fil: Casanova, D. Universidad Nacional del Centro de la Provincia de Buenos Aires, Facultad de Ciencias Veterinarias; Argentina

Delayed type hypersensitivity induced by intradermal inoculation of a Neospora caninum tachyzoite antigen in previously exposed cattle

The aim of this study was to evaluate delayed type hypersensitivity (DTH) induced by the intradermal inoculation of a Neospora caninum tachyzoite soluble lysate in cattle previously exposed with the protozoa. Four experimental groups were selected according to the prior exposure to N. caninum antigen. All cows were intradermally injected with a N. caninum tachyzoite soluble lysate and skinfold thickness growth at the inoculation sites was measured at 0, 24, 48, 72 and 96 h post inoculation (hpi). Additionally, specific antibodies and IFN-γ production were assessed. Cows experimentally infected with live N. caninum tachyzoites and cows naturally exposed to N. caninum developed skin reactions compatible with DTH between 24 and 96 hpi (p  0.05). Furthermore, serological status of the animals was not modified due to the intradermal inoculation. The highest IFN-γ production was observed at 15 days after intradermal inoculation (p < 0.05). Therefore, these results suggest that cattle previously exposed to N. caninum develop a reaction compatible with DTH which could be useful as in vivo cell mediated immunity parameter for assessed bovine neosporosis.EEA BalcarceFil: Fiorani, Franco. Consejo Nacional de Investigaciones Científicas y Técnicas;, ArgentinaFil: Armendano, Joaquín Ignacio. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; ArgentinaFil: Hecker, Yanina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Araoz, Virginia. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Balcarce; ArgentinaFil: Canton, German Jose. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Balcarce; ArgentinaFil: Leunda, María Rosa. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Balcarce; ArgentinaFil: Pereyra, Susana Beatriz. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Balcarce; ArgentinaFil: Corva, Pablo. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; ArgentinaFil: Odeon, Anselmo Carlos. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Balcarce; ArgentinaFil: Moore, Prando Dadin. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentin