ABSTRACT The objective of this study was to evaluate the effect of intronic single nucleotide polymorphisms (SNP) on temperament traits in a Brahman cattle population. The SNP located in CACNG4, EXOC4, NRXN3, and SLC9A4 candidate genes were genotyped in 250 animals with temperament records of exit velocity, pen score, and temperament score. Rs3423464051:G>A in the CACNG4 gene was associated with exit velocity and temperament score. An in silico analysis of the five intronic SNP showed that alternative alleles of CACNG4-rs3423464051, EXOC4-rs109393235, and SLC9A4-rs109722627 SNP could alter branch point sites during splicing, while a protein–protein interaction network analysis demonstrated a GRIA2 gene-mediated interaction between CACNG4 and NRXN3. The present results support previously reported evidence regarding bovine temperament-related candidate genes, particularly CACNG4, which is a confirmed candidate gene in need of more detailed analyses to reveal its role in temperament-related traits.

Resumen Coronavirus 19 (COVID-19), es una enfermedad viral prevalente y diseminada a nivel mundial, considerada una pandemia con alta tasa de mortalidad. A la fecha no existen estudios que describan la influencia de las variables asociadas a la enfermedad en el estado fronterizo de Tamaulipas, México. El objetivo del presente estudio fue evaluar y analizar las características, complicaciones, tasas de letalidad y factores de riesgo asociados a mortalidad en paciente positivos a COVID-19 en el estado de Tamaulipas, a un año de la emergencia local. Se utilizó la frecuencia de casos observados en relación a características, complicaciones y comorbilidades para estimar prevalencias y tasas de letalidad. Se ajustó un modelo de regresión logística multivariada para estimar los factores de riesgo significativos y se utilizaron curvas de supervivencia de Kaplan-Meier para describir las comorbilidades más importantes. Los análisis indicaron una mayor infección en pacientes en edad productiva, con una probabilidad significativa de muerte a partir de los 40 años, más evidente en pacientes masculinos. Los riesgos asociados a la hospitalización, como intubación endotraqueal y neumonía, son factores muy importantes. Las comorbilidades con alta prevalencia (diabetes, hipertensión y obesidad) y enfermedad renal crónica (ERC) están asociados significativamente (P < 0.01) a mayor mortalidad por COVID-19 en pacientes positivos. El presente estudio demostró algunos patrones generales de prevalencia y tasas de letalidad por COVID-19, por lo que se sugieren particularidades en los factores asociados a mortalidad en la población de Tamaulipas que requieren atención en sus grupos vulnerables, sobre todo en posibles casos de rebrotes de la enfermedad.

Abstract Coronavirus 19 (COVID-19) is a prevalent and globally disseminated viral disease that has become a pandemic associated with a high case fatality rate. To date, there are no published studies that describe the influence of the variables associated with the disease, specifically in the border state of Tamaulipas, Mexico. The objective of the present study was to assess the characteristics, complications, fatality rates and risk factors associated to mortality in patients positive to COVID-19 in Tamaulipas, one year after the local emergency. Descriptive frequency of characteristics, complications for prevalence and case fatality rates were used. A multivariate logistic regression model was adjusted to estimate the meaningful risk factors, and Kaplan-Meier survival curves were used to describe the most important comorbidities. The analysis indicated higher infection rates in patients of productive age, with a significant death probability in male patients from the age of 40. The risks associated with hospitalization, such as endotracheal intubation and the presence of pneumonia are important risk factors. Comorbidities with high prevalence; diabetes, hypertension, obesity, and chronic kidney disease (CKD) were significantly associated (P < 0.01) with higher COVID-19 mortality risk in the assessed population. The present study demonstrated some COVID-19 general patterns on frequency and mortality rates. It also suggested particularities in factors associated to mortality in the Tamaulipas population, which require proper attention in vulnerable groups, especially in future outbreaks of the disease.

ABSTRACT Introduction: COVID-19 is a viral disease disseminated worldwide, considered a pandemic with a high mortality rate, whose epidemiological study is fundamental to understand the risk associated with specific populations. Objectives: Estimate the case fatality rates and risk factors associated with mortality from COVID-19 in the five states with more infections in Mexico. Methods: 297,230 COVID-19 positive patients were analyzed using RT-PCR tests from 475 monitoring units in five states of Mexico. Case fatality rates and probability ratios were estimated by adjusting a multivariate logistic regression model. Risk factors were considered in a model that included the effects of sex, age, smoking habits, hospitalization history, pneumonia diagnosis, and comorbidities such as diabetes, hypertension, chronic obstructive pulmonary disease, asthma, immunosuppression, chronic kidney disease, and cardiovascular disease, among others. Results: There is greater contagion among people aged 41 to 60 years. More than 90% of deaths occurred after the age of 41, with the case fatality rate increasing at an older age. Men showed a higher proportion of cases, deaths and case fatality rate. Multivariate logistic analysis showed that age, sex, hospitalization, pneumonia, diabetes, and chronic kidney disease are significant risk factors (p < 0.0001) for COVID-19 mortality. Conclusions: In Mexico, age, sex, hospitalization, pneumonia, diabetes and chronic kidney disease are factors that increase the risk of mortality from COVID-19. It is suggested to take this information into account to determine vulnerable groups and increase attention to them to reduce, as far as possible, the risk of contagion and mortality.

RESUMEN Introducción: La COVID-19 es una enfermedad viral diseminada a nivel mundial, que es considerada una pandemia con alta tasa de mortalidad, cuyo estudio epidemiológico es fundamental para entender el riesgo asociado a poblaciones específicas. Objetivos: Estimar las tasas de letalidad y factores de riesgo asociados a mortalidad por COVID-19 en cinco Estados con más contagios en México. Métodos: Se analizaron de 297 230 pacientes positivos a COVID-19 mediante prueba de RT-PCR procedentes de 475 unidades de monitoreo en cinco Estados de México. Se estimaron tasas de letalidad y razones de probabilidad mediante el ajuste de un modelo de regresión logística multivariada. Se consideraron los factores de riesgo en un modelo que incluyó los efectos del sexo, edad, hábitos de fumador, historial de hospitalización, diagnóstico de neumonía y comorbilidades como diabetes, hipertensión, enfermedad pulmonar obstructiva crónica, asma, inmunodepresión, enfermedad renal crónica y enfermedades cardiovasculares, entre otras. Resultados: Existe mayor contagio entre las personas de 41 a 60 años de edad. Más del 90 % de los fallecimientos ocurrieron después de los 41 años, con aumento de la tasa de letalidad a mayor edad. Los hombres mostraron mayor proporción de casos, fallecimientos y tasa de letalidad. El análisis logístico multivariado mostró que la edad, sexo, hospitalización, neumonía, diabetes y enfermedad renal crónica son factores de riesgo significativos (p < 0,0001) para mortalidad por COVID-19. Conclusiones: En México la edad, el sexo, la hospitalización, neumonía, diabetes y enfermedad renal crónica son factores que aumentan el riesgo de mortalidad por COVID-19. Se sugiere tener en cuenta esta información para determinar los grupos vulnerables e incrementar la atención sobre ellos para disminuir, en la medida de lo posible, el riesgo de contagio y mortalidad.

Abstract The aim of this study was to estimate allelic and genotypic frequencies of markers in the leptin (LEP), pituitary transcription factor (PIT-1) and luteinizing hormone receptor (LHR) genes and evaluate their effects on reproductive traits and milk yield of Holstein cattle. Data from 147 cows from department of Francisco Morazán, Honduras, were collected and PCR-Restriction Fragment Length Polymorphism (RFLP) assays were performed to characterize the PIT-1-HinfI, LEP- A59V and LHR-rs41256848 polymorphisms. To estimate the effect of genotypes on reproductive traits and milk yield fixed and mixed linear models were fitted. The frequencies of the genotypes CC, CT and TT of A59V, AA, AB and BB of HinfI, and CC, CG and GG of rs41256848 were 0.46, 0.33 and, 0.21; 0.09, 0.32 and 0.58; and 0.37, 0.61 and 0.02, respectively. The genotypes of LEP and LHR showed deviations from Hardy-Weinberg equilibrium. The A59V polymorphism was significantly associated with the calving to conception interval (CCI) (p=0.01), being the C allele favorable. The HinfI and rs41256848 polymorphism were significantly associated (p=0.08 and p=0.04) with age to first calving (AFC), being the A and G the alleles favorable associated, respectively. The results suggest that LEP, PIT and LHR polymorphisms can probably act as candidate to be used in marker-assisted selection for AFC and CCI traits.

Abstract A full understanding of how specific genes affect live weight variables is required for their incorporation into genetic improvement programs. An analysis was done of the allelic frequencies of 28 single nucleotide polymorphisms (SNP) located in candidate genes for growth in cattle to identify their effect on live weight traits in Charolais and Simmental herds in the state of Tamaulipas, Mexico. Hair samples were collected from 313 animals and genotyped using the Sequenom MassARRAY system. Genotype analysis showed that all the markers were polymorphic in the evaluated populations and their allelic frequencies were significantly different between the two breeds (P<0.05). An association analysis found that in the Charolais population the marker PRL + 2723 had a significant effect (P= 0.0350) on birth weight and the marker GHR-6.1 affected weaning weight (P= 0.0226). In the Simmental population GHR-6.1 was associated with yearling weight and the marker LEP-3100 (P=0.0249) had a significant effect on weaning weight. The tested 28 SNP panel is polymorphic in both breeds and three of the markers had a significant effect on the evaluated live weight parameters. They can therefore be potentially validated for use as tools in the selection and breeding of beef cattle in Tamaulipas.

Resumen El objetivo del estudio fue analizar las frecuencias alélicas de 28 Polimorfismos de un solo nucleótido (SNP) localizados en genes candidatos para crecimiento en bovinos, así como determinar su efecto sobre rasgos de peso vivo en hatos de las razas Charolais y Simmental. Se tomaron muestras de pelo de 313 animales provenientes de cinco hatos ubicados en cuatro municipios de Tamaulipas y se genotipificaron con la tecnología de Sequenom Mass Array. Todos los marcadores resultaron ser polimórficos en las poblaciones evaluadas y sus frecuencias alélicas fueron significativamente diferentes entre razas (P<0.05). El análisis de asociación determinó que en los animales de la raza Charolais, el marcador PRL+2723 tiene un efecto significativo (P=0.0350) sobre el peso al nacimiento y el marcador localizado en el gen GHR (GHR-6.1), sobre peso al destete (P=0.0226). El GHR-6.1 también se asoció con el peso al año en los animales de la raza Simmental. El marcador LEP-3100 (P=0.0249) también tuvo un efecto significativo sobre el peso al destete en los animales Simmental. El panel probado es polimórfico en las dos razas evaluadas y tres de los marcadores tuvieron efecto significativo en los parámetros de peso vivo evaluados, por lo que tienen el potencial de validarse y usarse como una herramienta adicional en la selección y mejoramiento genético del ganado de carne en Tamaulipas.

ABSTRACT. The aim of the present work was to perform a genetic verification of Herichthys species and assess their phylogenetic relationship by Cytochrome B gene resequencing in two sampling sites from Tamaulipas. Samples from Panal river in Playa Tepehuajes, Soto la Marina and samples from Carrizal river in Aldama were included. The complete sequences were analyzed with bioinformatics tools and the genetic similarity showed that Aldama samples resembled Herichthys carpintis species (> 99%) and Tepehuajes samples were confirmed as Herichthys cyanoguttatus. The assessed phylogenetic trees for genetic distance comparison among current samples and other cichlids species support the previously found results. This study suggest that cytochrome B gene is useful for genetic identification of cichlid species, such as from Tamaulipas.

RESUMEN. El objetivo del presente estudio fue verificar genéticamente la identidad de especies del genero Herichthys y estudiar su relación fiolgenética utilizando secuencias de citocromo B mitocondrial. Se incluyeron muestras de dos sitios de Tamaulipas de dicha especie: en el río Panal ubicado en Playa Tepehuajes, Soto la Marina y en el río Carrizal ubicado en Aldama. Se analizaron las secuencias completas del gen mitocondrial citocromo B con herramientas bioinformáticas, los resultados de similitud genética indican que las muestras de Aldama tienen mayor similitud (> 99%) con la especie Herichthys carpintis. Mientras que las muestras de Tepehuajes, confirmaron la identidad supuesta con Herichthys cyanoguttatus. Los árboles filogenéticos analizados con la finalidad de comparar la distancia genética de las muestras con diferentes especies de cíclidos, confirmaron la similitud encontrada previamente. Los resultados sugieren que el citocromo B es un marcador útil en la identificación de especies de cíclidos de Tamaulipas.

Abstract We investigated whether a panel of molecular markers previously associated with temperament has an effect on live growth traits. Phenotypic data from 412 Charolais cows categorized according to their age in adult and young cows were used to determine Pearson's correlations between birth (BW), weaning (WW), and yearling live (YW) weight and temperament traits (measured as exit velocity [EV] and temperament score [TS]). For association analysis, selective genotyping of a group of 80 cows identified as the most docile and temperamental were genotyped with a 151-SNP (single-nucleotide polymorphisms) panel of molecular markers previously associated with temperament. Significant Pearson's correlations between birth weight and weaning weight and the two temperament measurements (EV and TS) were observed only in the young cow group. Significant effects of ten SNP on BW and WW were observed. Four markers located on candidate genes for temperament traits also had an effect on birth weight and weaning weight in Charolais cows, which indicates that both traits could be influenced by the same genes.

Abstract: The objective of this study was to compare the effects of a methodology for the climatic season classification that traditionally had been used as birth season (BS) in statistical assessments. This methodology bases in an aridity index (AI) to classify BS using meteorological historic information. Using a 7,460-pedigree animals dataset were fitted two statistical models for birth and weaning weights of Charolais cattle. Genetic models included the fixed effect of contemporary groups (CG= herd, sex, year and BS) and dam age as a covariate (linear and quadratic). Same models compared with a traditional season classification for BS. When variance component and expected progeny differences (EPD) were predicted with their accuracies, models were statistically different accordingly to the likelihood ratio test (P<0.01). An improvement and reduction in CG conformation (25 %) were observed for those models including IA based BS. The main effect in assessed models was the ranking changes in EPD from both traits. This classification method of birth season can improve the model fitting in animal production based in extensive systems.

Resumen: El objetivo fue comparar los efectos de una metodología para la clasificación de épocas climáticas, que tradicionalmente son utilizadas para establecer épocas de nacimiento (EN) en estudios y experimentos estadísticos. Esta metodología se basa en un índice de aridez (IA) para clasificar las EN utilizando información meteorológica histórica. Se trabajó una base de datos con un pedigrí de 7,460 animales, se ajustaron dos modelos para peso al nacimiento y peso al destete en bovinos Charolais manejados en pastoreo extensivo. Los modelos incluyeron el efecto fijo de grupo contemporáneo (GC= subclase de hato, sexo, año y EN) y edad de la madre. Los mismos modelos se compararon utilizando una clasificación tradicional de estaciones del año para clasificar las EN. Al estimar los componentes de varianza y valores genéticos (DEP) con sus exactitudes, los modelos fueron diferentes de acuerdo a la prueba de razón de verosimilitudes (P<0.01). El número de GC se redujo en 25 % para la EN basada en el IA, con GC con mayor número de individuos. El principal efecto observado en los modelos analizados fue el cambio en la jerarquización de las DEP para ambas características. Este método de clasificación de épocas de nacimiento, puede ayudar a mejorar el ajuste de modelos estadísticos en los sistemas ganaderos manejados en pastoreo extensivo.

ABSTRACT The signals of selection using candidate genes polymorphism were studied in five zebu breeds of Mexico. Three loci from GHRH and complementarily Steroyl Co Desaturase F762, Dopamine Beta Hydroxilase 17299, and LEP3272 were identified under selection. Findings depict Zebu selection pressure mainly on Brahman breed resulting in a divergent structure pattern.

ABSTRACT Channel catfish, Ictalurus punctatus, is one of the most important fish on Mexican aquaculture and despite its productive potential, there is very few information regarding the distribution of Ictalurus species in Mexican territory. Sequencing of Cytochrome Oxidase I gene has proved to be very useful for the identification of fish specimens and sub-products. In the present, we report the molecular identification of 93 feral, commercial and domestic catfish individuals. All domestic fish were positively identified as channel catfish. Commercial samples were identified as Ictalurus punctatus, Ictalurus lupus, and Ictalurus furcatus, providing evidence that catfish represents a generic label for separate fish species. We also report the presence of feral I. punctatus on eight novel locations within Mexican territory, I. lupus on three and I. furcatus in one. Thus, we propose that molecular identification by DNA barcoding represents a powerful tool in the study of catfish populations and sub-products.

Abstract: K-casein (CSN3) gene is of particular interest in goat production due to the effect of its polymorphisms on milk quality and composition. The objective of this study was to assess the genotypic and allelic frequencies in CSN3 gene in the Saanen goat breed and its effect on milk production and some of its compositional traits. Allelic discrimination assays were designed to determine the variants (A, B or C) using qPCR and allelic discrimination method. Allelic frequencies for A, B and C were 0.23, 0.64 and 0.13, respectively. Association analysis indicated that the CSN3 was significantly associated only with protein percentage (p = 0.006). Results indicated that animals with AC, BB and CC genotypes showed higher milk protein percentage than those with genotype AB. This evidence suggests that genotypes favorable to this associated trait could be included into Saanen goat breeding strategies.

Resumen: El gen de la к-caseína (CSN3) es de especial interés debido al efecto de sus polimorfismos sobre la calidad y composición de la leche. El objetivo de este estudio fue investigar las frecuencias genotípicas y alélicas del gen CSN3 en la raza caprina Saanen y su efecto sobre la producción de leche y algunas de sus características de composición. Se diseñaron diferentes ensayos de discriminación alélica para determinar las variantes (A, B y C) mediante qPCR. Las frecuencias alélicas para las variantes A, B y C fueron de 0.23, 0.64 y 0.13, respectivamente. El análisis de asociación indicó que el gen CSN3 esta asociado solamente al porcentaje de proteína en leche (p = 0.006). Los resultados mostraron que los animales con los genotipos AC, BB y CC producen leche con mayor porcentaje de proteína que aquellos con el genotipo AB. Esta evidencia sugiere que los genotipos favorables para la característica asociada podrían incluirse en estrategias de selección asistida por marcadores en cabras de la raza Saanen.

The aim of this study was to determine the effect of environmental factors on milk production of Suiz-Bu cows reared under the Mexican tropical conditions. Milk yield records of 728 cows that were available from 2012 to 2014 were analyzed. Cows were milked twice a day as of the fifth day of calving, fed under grazing conditions and supplemented with commercial concentrates. Variables of milk production at 305 days (PL305) and average milk yield per day (MPD) were analyzed using a mixed model that included effects of lactation (NL), year of calving (AP), season of calving (EP), and simple interactions. The year of calving was statistically significant for PL305 and PMD (p<0.05), cows that calved during the rainy season had greater milk production (PL305 and PMD) than those calving during the dry season (p<0.05), and first calvers had lower PL305 than cows with two or three lactations (p<0.05). Moreover, the effects of interactions were significant (p<0.05)

El objetivo del presente trabajo fue determinar el efecto de factores ambientales sobre la producción de leche de vacas Suiz-Bú en las condiciones del trópico mexicano. Se analizaron los registros de producción de leche de 728 vacas con información disponible de los años 2012 al 2014. Las vacas se ordeñaban dos veces al día a partir del quinto día posparto y eran alimentadas bajo condiciones de pastoreo y suplementación con concentrado comercial. Las variables producción de leche a 305 días (PL305) y media de producción diaria (MPD) fueron analizadas con un modelo mixto que incluyó efectos de número de lactancia (NL), año de parto (AP), época de parto (EP) y las interacciones simples. El año de parto fue estadísticamente significativo para PL305 y PMD (p<0.05), las vacas que parieron en la época lluviosa tuvieron una mayor producción, tanto PL305 como PMD, que aquellas que parieron en época seca (p<0.05), y las vacas de primer parto tuvieron una menor PL305 que vacas con dos o tres lactancias (p<0.05). Asimismo, los efectos de las interacciones fueron significativas (p<0.05)

The channel catfish is an important aquaculture species in Mexico mostly managed in traditional production systems. The state of Tamaulipas has been the source of diverse populations of channel catfish in the country, however there is no documentary evidence of this. Therefore, the objective of this study was to confirm the genetic origin of populations of channel catfish (Ictalurus punctatus) of west central Mexico by microsatellite DNA markers. The study included four domestic populations from Michoacán, Zacatecas and Jalisco and two reference founder populations from Tamaulipas and Coahuila. The analysis was performed with a panel of 13 microsatellites. Some parameters of diversity and population structure were evaluated. The six populations showed excess of heterozygotes and a coefficient endogamy F IS ≤ -0.014. The analysis of gene structure was determined by a paired comparison populations, and indicated the 5.92% of variation among populations (F ST = 0.059, P < 0.001). The assessment approaches identified the population of Tamaulipas as the most likely genetic origin of channel catfish populations currently used in the evaluated states.

El bagre de canal es una especie importante en la acuacultura de México y se produce en sistemas tradicionales. El estado de Tamaulipas ha sido el origen de diversas poblaciones de bagre de canal en el país. Por ello, el objetivo del presente trabajo fue evaluar el origen genético de poblaciones de bagre de canal (Ictalurus punctatus) introducidas en el centro occidental de México mediante marcadores de ADN. El estudio comprendió cuatro poblaciones de Michoacán, Zacatecas y Jalisco, y se utilizaron como referencia fundadora dos poblaciones correspondientes a Tamaulipas y Coahuila. El análisis se realizó con un panel de 13 microsatélites previamente reportados. Se evaluaron diversos parámetros de diversidad y estructura poblacional. Las seis poblaciones presentaron exceso de heterocigotos y un coeficiente de endogamia F IS ≤ -0,014. El análisis de la estructura genética se determinó mediante una comparación pareada de poblaciones e identificó un 5,92% explicado por la variación entre poblaciones (F ST = 0,059, P < 0,001). Mediante las aproximaciones de análisis se identificó a la población de Tamaulipas como el origen genético más probable de las poblaciones de bagre en los estados evaluados.

Abstract: Dairy cattle shows their genetic potential in different efficiency levels depending on the region in which they live; this effect is referred to as interaction genotype x environment (IGE) and may have implications for the genetic improvement of dairy cattle in Mexico. This phenomenon should be considered when importing genetic resources from other countries, and even from other regions within the same country. The objective of this study was to review the IGE in the genetic improvement of dairy cattle. The genetic improvement programs need to be based on records of the productions carried out in each of the production units. This can help identify the factors affecting the genetic production and how this in turn reflects the achieved production. It is concluded that the selection of the sires of the next generation must be conducted under the same conditions as where their progenies will be used if the IGE is to be minimized.

Resumen: El ganado bovino lechero expresa con diferente nivel de eficiencia su potencial genético depen diendo de la región en que se desarrolla; a este efecto se le denomina interacción genotipo x ambiente (IGA), y puede afectar la eficiencia de los programas de mejoramiento genético. Este fenómeno debe ser considerado al importar recursos genéticos de otros países e incluso de otras regiones dentro de un mismo país. El objetivo de este trabajo fue analizar los principales as pectos de la IGA en el mejoramiento genético de ganado bovino lechero. Los programas de me joramiento genético deben estar basados en el registro de las operaciones que se realizan en cada una de las unidades de operación, lo que permitirá establecer cuales fueron los principales factores que influyeron en la expresión del potencial genético y su reflejo en la producción alcanzada. Se concluye que la selección de los sementales de la próxima generación deberá realizarse en las mismas condiciones donde se usarán sus progenies, buscando minimizar la IGA.

Abstract: Allelic and genotypic frequencies of eight markers previously associated to genetic disorders and meat quality and located in the calpain (CAPN1-4751 and CAPN1-316), calpastatin (CAST-T1), thyroglobulin (TG5), myostatin (MSTN, Q204X), argininosuccinate synthase (ASS), monophosphate synthase (UMPS) and myophosphorylase (PYGM) genes, were determined from 493 registered Charolais animals sampled from two herds located at Sonora (n= 157) and three at Nuevo León (n= 336), Mexico. No carriers of mutated alleles of ASS and UMPS genes were found, but carriers of the MSTN Q204X allele were identified at frequencies of ≤ 1 % in Sonora populations and 8.6 to 14.4 % in Nuevo Leon. In addition, carriers of PYGM marker were identified at frequencies of 6.49 and 1% in a herd from Sonora and other from Nuevo León, respectively. Analysis of gene differentiation among herds and with four loci showed that there are highly significant differences within Northwest populations (P<0.0001) and between them and the Northeast (P<0.001), differentiation is mainly explained by the loci CAPN-316 and TG5. According to the obtained results, the periodic monitoring of the PYGM marker gene and of the allele Q204X the MSTN gene is propose; also it is important to implement strategies to confirm the usefulness of those markers associated with quality and productivity as a tool to complement breeding programs.

Resumen: Se determinaron las frecuencias alélicas y genotípicas de ocho marcadores localizados en los genes calpaína (CAPN, 4751 y 316), calpastatina (CASTT1) y tiroglobulina (TG5), asociados a calidad de carne, y en los genes, miostatina (MSTN, Q204X), arginino succinato sintasa (ASS), monofosfato sintasa (UMPS) y miofosforilasa (PYGM), asociados a enfermedades genéticas de ganado bovino. Se muestrearon 493 animales Charolais de registro de dos hatos ubicados en Sonora (n=157) y tres en Nuevo León (n=336). No se encontraron portadores de los alelos T-ASS y T-UMPS, pero sí portadores del alelo Q204X del gen MSTN en frecuencias de ≤ 1 % en las poblaciones de Sonora y de 8.6 a 14.4 % en las de Nuevo León. Además, se identificaron portadores del marcador del gen PYGM, en frecuencias del 6.5 y de 1.0 % para un hato de Sonora y otro de Nuevo León, respectivamente. El análisis de diferenciación génica pareado entre las poblaciones y con los cuatro loci mostró que hay diferencias altamente significativas dentro de poblaciones del noroeste (P<0.0001) y entre éstas y las del noreste (P<0.001), la cual es explicada principalmente por los loci CAPN-316 y TG5. De acuerdo a los resultados obtenidos se recomienda el monitoreo del marcador del gen PYGM y del alelo Q204X del gen MSTN, así como también implementar estrategias para confirmar la utilidad de los marcadores asociados a calidad y productividad como herramienta para complementar los programas de mejoramiento genético.