RESUMO
The mangrove oyster (Crassostrea gasar) is Brazil's second most cultured species and presents a high potential for aquaculture. However, artificial selection in a highly fecund species and significant variance in reproductive success can result in the loss of genetic diversity and increases the inbreeding rate, especially in cultivated populations. In this study, we investigated the genetic structure and diversity of C. gasar in wild and cultivated populations using 14 microsatellites. Spatial genetic comparisons revealed the existence of two main genetic groups of C. gasar, one comprising the population in cultivation and the other formed by wild populations along the southern and southeastern Brazilian coasts. Although no common genetic structure exists among wild populations, it is possible to observe a distribution gradient based on discriminant analysis of principal components consistent with their geographic distribution. However, it is insufficient to differentiate them genetically. Despite artificial reproduction, the genetic diversity values of the cultivated population remained relatively high and did not show a reduction. Therefore, monitoring the cultivated population and establishing reference values for genetic diversity will allow the adoption of strategies both for the viability of the cultivated population and the management of wild populations.
Assuntos
Crassostrea , Animais , Crassostrea/genética , Brasil/epidemiologia , Alimentos Marinhos , Aquicultura , Estruturas GenéticasRESUMO
The selective breeding of laboratory rodents with different anxiety-related traits is the subject of growing interest. The present study compared the effects of the benzodiazepine midazolam in the elevated plus maze (EPM) test of anxiety in two lines of Wistar rats that were selectively bred in our laboratory for either high or low anxiety-like traits based on a contextual freezing conditioning paradigm. After phenotyping anxiety-like traits (i.e., conditioned freezing behavior), Carioca High-Freezing [CHF], Carioca Low-Freezing [CLF]) and control rats were intraperitoneally injected (1.0â¯ml/kg) with .9 % saline or midazolam (.25, .5, .75, and 1.0â¯mg/kg) and subjected to the EPM 30â¯min later. After the saline injection, the CHF and CLF groups exhibited lower and higher open-arm exploration in the EPM, respectively, compared with control rats. These results indicate that anxiety-related traits previously selected from an associative learning paradigm can also be phenotypically expressed in an ethologically based animal model of anxiety. All midazolam doses significantly increased open-arm exploration in both CHF and control animals, but this anxiolytic-like effect in CLF rats was only observed at the lowest dose tested (.25â¯mg/kg). The present findings indicate that these two breeding lines of rats are a useful model for studying anxiety, and the anxiolytic effect of midazolam depends on genetic variability that is associated with basal reactions to threatening situations.
Assuntos
Condicionamento Clássico/efeitos dos fármacos , Resposta de Imobilidade Tônica/efeitos dos fármacos , Midazolam/farmacologia , Animais , Ansiolíticos/farmacologia , Relação Dose-Resposta a Droga , Aprendizagem em Labirinto , Fenótipo , Ratos Endogâmicos , Seleção ArtificialRESUMO
Ethanol use is widespread in adolescents, yet only some transition to problematic drinking. It is important to understand why the risk for problematic drinking varies across sub-groups of adolescents. This study reports a short-term selection program to generate Wistar rat lines (high and low adolescent ethanol drinking, ADHI and ADLO lines, respectively) that significantly differ in ethanol drinking at adolescence. The S0 generation and filial generations 1 (S1), S2, and S3 of ADHI and ADLO offspring were tested for basal or stress-induced ethanol intake at adulthood, or for shelter-seeking and risk-taking in the multivariate concentric square field test (MSCF). The study generated lines with significant differences in free-choice ethanol drinking at adolescence. The effects of the selection were observed at adulthood, beyond the stage in which the selection was conducted: S1-ADHI but not S1-ADLO adult male rats exhibited stress-induced drinking. These effects were associated with significant alterations in shelter-seeking and risk-taking behaviors. ADHI rats spent significantly less time in areas of the MSCF whose exploration entails risk-taking and significantly more time in dark, sheltered areas. Some of these effects were normalized by the administration of 0.5 g/kg ethanol. There were no line differences in ethanol-induced latency to lose the righting reflex or sleep time. These findings indicate that genetic risk of enhanced ethanol intake at adolescence is still present at adulthood, long after the developmental window when the selective breeding occurred. Exposure to stress at adulthood triggers the vulnerability associated with this genetic risk, an effect associated with enhanced anxiety.
Assuntos
Consumo de Bebidas Alcoólicas/genética , Consumo de Bebidas Alcoólicas/fisiopatologia , Ansiedade/fisiopatologia , Comportamento Animal/fisiologia , Depressores do Sistema Nervoso Central/farmacologia , Etanol/farmacologia , Predisposição Genética para Doença , Estresse Psicológico/fisiopatologia , Fatores Etários , Animais , Ansiedade/genética , Depressores do Sistema Nervoso Central/administração & dosagem , Modelos Animais de Doenças , Etanol/administração & dosagem , Feminino , Masculino , Fenótipo , Ratos , Ratos Wistar , Assunção de Riscos , Seleção Artificial , Estresse Psicológico/complicaçõesRESUMO
The estimation of linkage disequilibrium between molecular markers within a population is critical when establishing the minimum number of markers required for association studies, genomic selection, and inferring historical events influencing different populations. This work aimed to evaluate the extent and decay of linkage disequilibrium in a coho salmon breeding population using a high-density SNP array. Linkage disequilibrium was estimated between a total of 93,502 SNPs found in 64 individuals (33 dams and 31 sires) from the breeding population. The markers encompass all 30 coho salmon chromosomes and comprise 1,684.62 Mb of the genome. The average density of markers per chromosome ranged from 48.31 to 66 per 1 Mb. The minor allele frequency averaged 0.26 (with a range from 0.22 to 0.27). The overall average linkage disequilibrium among SNPs pairs measured as r 2 was 0.10. The Average r 2 value decreased with increasing physical distance, with values ranging from 0.21 to 0.07 at a distance lower than 1 kb and up to 10 Mb, respectively. An r 2 threshold of 0.2 was reached at distance of approximately 40 Kb. Chromosomes Okis05, Okis15 and Okis28 showed high levels of linkage disequilibrium (>0.20 at distances lower than 1 Mb). Average r 2 values were lower than 0.15 for all chromosomes at distances greater than 4 Mb. An effective population size of 43 was estimated for the population 10 generations ago, and 325, for 139 generations ago. Based on the effective number of chromosome segments, we suggest that at least 74,000 SNPs would be necessary for an association mapping study and genomic predictions. Therefore, the SNP panel used allowed us to capture high-resolution information in the farmed coho salmon population. Furthermore, based on the contemporary N e, a new mate allocation strategy is suggested to increase the effective population size.
RESUMO
Genetic gain for final weight and influence of selective breeding on several zootechnical and morphometric parameters of selected Nile tilapia within different genetic groups, after one generation of individual selection, were evaluated. After selection, five genetic groups were sampled for current analysis. Ten separate matings were carried out in 50 m² fish ponds for five selected groups and five non-selected groups (sampled fish with mean weight of the same genetic groups for control). Thirty females from each genetic group were mated with twelve males, totaling 300 females and 120 males. Larvae from ponds were collected after 21 days, from which 500 larvae were sampled per genetic group, with hatchery in ten 100L tanks, separately for each group, followed by rearing in ten 1 m³ hapas in a 300 m² fish pond. Afterwards, 30 tilapias (30.0±1.6 g) from each genetic group, totaling 300 animals, were tagged with magnetic transponder. These were distributed into three 50 m² ponds with ten animals of each group per fish pond. After 140 days of rearing, the animals were harvested for evaluation. Individual selection was characterized by final and fillet weight gain, respectively at 8.4% and 9.5%. In addition, the results showed an increase in total length, standard length, body height, body width and corrected length. However, no modifications occurred in parameters such as survival...
Este estudo teve como objetivo avaliar o ganho genético para peso final, e a influência da seleção em outras variáveis zootécnicas e morfométricas, de tilápias-do-nilo selecionadas dentro de diferentes grupos genéticos, após uma geração de seleção individual. Após a seleção, cinco grupos genéticos foram amostrados para realizar o estudo. Foram realizados dez acasalamentos em viveiros de 50 m², separadamente, para cinco grupos selecionados e cinco não selecionados (peixes amostrados da média de peso dos mesmos grupos genéticos para serem utilizados como controle), totalizando dez viveiros. De cada população foram acasaladas 30 fêmeas com 12 machos, totalizando 300 fêmeas e 120 machos. Após 21 dias, foram coletadas as nuvens, das quais 500 larvas por grupo genético foram amostradas, realizando a alevinagem em 10 tanques de 100 L, separadamente para cada grupo, seguido de recria em dez tanques-rede de 1 m³ dentro de um viveiro de 300 m². Posteriormente 30 tilápias (30,0±1,6 g) de cada grupo genético foram marcadas com transponder magnético, totalizando 300 animais. Estes foram distribuídos em três viveiros de 50 m², de modo a ficar 10 animais de cada grupo por viveiro. Após 140 dias de cultivo, os animais foram despescados para avaliação. A seleção individual realizada ocasionou um ganho do peso final do cultivo e no peso do filé de 8,4% e 9,5%, respectivamente. Além disso...
Assuntos
Animais , Ciclídeos/anatomia & histologia , Ciclídeos/crescimento & desenvolvimento , Ciclídeos/genética , Peso Corporal/genética , Pesos e Medidas Corporais/veterinária , Seleção Genética , Melhoramento Genético/métodosRESUMO
Genetic gain for final weight and influence of selective breeding on several zootechnical and morphometric parameters of selected Nile tilapia within different genetic groups, after one generation of individual selection, were evaluated. After selection, five genetic groups were sampled for current analysis. Ten separate matings were carried out in 50 m² fish ponds for five selected groups and five non-selected groups (sampled fish with mean weight of the same genetic groups for control). Thirty females from each genetic group were mated with twelve males, totaling 300 females and 120 males. Larvae from ponds were collected after 21 days, from which 500 larvae were sampled per genetic group, with hatchery in ten 100L tanks, separately for each group, followed by rearing in ten 1 m³ hapas in a 300 m² fish pond. Afterwards, 30 tilapias (30.0±1.6 g) from each genetic group, totaling 300 animals, were tagged with magnetic transponder. These were distributed into three 50 m² ponds with ten animals of each group per fish pond. After 140 days of rearing, the animals were harvested for evaluation. Individual selection was characterized by final and fillet weight gain, respectively at 8.4% and 9.5%. In addition, the results showed an increase in total length, standard length, body height, body width and corrected length. However, no modifications occurred in parameters such as survival...(AU)
Este estudo teve como objetivo avaliar o ganho genético para peso final, e a influência da seleção em outras variáveis zootécnicas e morfométricas, de tilápias-do-nilo selecionadas dentro de diferentes grupos genéticos, após uma geração de seleção individual. Após a seleção, cinco grupos genéticos foram amostrados para realizar o estudo. Foram realizados dez acasalamentos em viveiros de 50 m², separadamente, para cinco grupos selecionados e cinco não selecionados (peixes amostrados da média de peso dos mesmos grupos genéticos para serem utilizados como controle), totalizando dez viveiros. De cada população foram acasaladas 30 fêmeas com 12 machos, totalizando 300 fêmeas e 120 machos. Após 21 dias, foram coletadas as nuvens, das quais 500 larvas por grupo genético foram amostradas, realizando a alevinagem em 10 tanques de 100 L, separadamente para cada grupo, seguido de recria em dez tanques-rede de 1 m³ dentro de um viveiro de 300 m². Posteriormente 30 tilápias (30,0±1,6 g) de cada grupo genético foram marcadas com transponder magnético, totalizando 300 animais. Estes foram distribuídos em três viveiros de 50 m², de modo a ficar 10 animais de cada grupo por viveiro. Após 140 dias de cultivo, os animais foram despescados para avaliação. A seleção individual realizada ocasionou um ganho do peso final do cultivo e no peso do filé de 8,4% e 9,5%, respectivamente. Além disso...(AU)
Assuntos
Animais , Ciclídeos/anatomia & histologia , Ciclídeos/crescimento & desenvolvimento , Ciclídeos/genética , Seleção Genética , Pesos e Medidas Corporais/veterinária , Peso Corporal/genética , Melhoramento Genético/métodosRESUMO
Selective breeding of shrimp has major potential to enhance production traits, including growth and disease resistance. Genetic characterization of broodstock populations is a key element of breeding programs, as it enables decisions on inbreeding restrictions, family structure, and the potential use of genomic selection. Single Nucleotide Polymorphisms (SNPs) are suitable genetic markers for this purpose. A set of SNPs was developed to characterize commercial breeding stocks in Mexico. Individuals from local and imported lines were selected for sequencing using the nextRAD technique, resulting in the identification of 2619 SNPs. Genetic structure analysis showed three to five genetic groups of Ecuadorian and Mexican origins. A subset of 1231 SNPs has potential for stock identification and management. Further, three SNPs were identified as candidate sex-linked markers. The role of SNPs possibly associated with genes related to traits of importance to shrimp farming, such as growth and immune response, should be further investigated.
Assuntos
Código de Barras de DNA Taxonômico , Penaeidae/genética , Polimorfismo de Nucleotídeo Único , Animais , Cruzamento , Feminino , Marcadores Genéticos , MasculinoRESUMO
Piscirickettsia salmonis is one of the main infectious diseases affecting coho salmon (Oncorhynchus kisutch) farming, and current treatments have been ineffective for the control of this disease. Genetic improvement for P. salmonis resistance has been proposed as a feasible alternative for the control of this infectious disease in farmed fish. Genotyping by sequencing (GBS) strategies allow genotyping of hundreds of individuals with thousands of single nucleotide polymorphisms (SNPs), which can be used to perform genome wide association studies (GWAS) and predict genetic values using genome-wide information. We used double-digest restriction-site associated DNA (ddRAD) sequencing to dissect the genetic architecture of resistance against P. salmonis in a farmed coho salmon population and to identify molecular markers associated with the trait. We also evaluated genomic selection (GS) models in order to determine the potential to accelerate the genetic improvement of this trait by means of using genome-wide molecular information. A total of 764 individuals from 33 full-sib families (17 highly resistant and 16 highly susceptible) were experimentally challenged against P. salmonis and their genotypes were assayed using ddRAD sequencing. A total of 9,389 SNPs markers were identified in the population. These markers were used to test genomic selection models and compare different GWAS methodologies for resistance measured as day of death (DD) and binary survival (BIN). Genomic selection models showed higher accuracies than the traditional pedigree-based best linear unbiased prediction (PBLUP) method, for both DD and BIN. The models showed an improvement of up to 95% and 155% respectively over PBLUP. One SNP related with B-cell development was identified as a potential functional candidate associated with resistance to P. salmonis defined as DD.
Assuntos
DNA/genética , Resistência à Doença/genética , Estudo de Associação Genômica Ampla , Genômica , Oncorhynchus kisutch/genética , Oncorhynchus kisutch/microbiologia , Piscirickettsia/fisiologia , Mapeamento por Restrição/métodos , Animais , Cruzamento , Feminino , Doenças dos Peixes/genética , Doenças dos Peixes/microbiologia , Marcadores Genéticos , Estimativa de Kaplan-Meier , Masculino , LinhagemRESUMO
Chilean Farmed Atlantic salmon (Salmo salar) populations were established with individuals of both European and North American origins. These populations are expected to be highly genetically differentiated due to evolutionary history and poor gene flow between ancestral populations from different continents. The extent and decay of linkage disequilibrium (LD) among single nucleotide polymorphism (SNP) impacts the implementation of genome-wide association studies and genomic selection and provides relevant information about demographic processes of fish populations. We assessed the population structure and characterized the extent and decay of LD in three Chilean commercial populations of Atlantic salmon with North American (NAM), Scottish (SCO), and Norwegian (NOR) origin. A total of 123 animals were genotyped using a 159 K SNP Axiom® myDesignTM Genotyping Array. A total of 32 K SNP markers, representing the common SNPs along the three populations after quality control were used. The principal component analysis explained 78.9% of the genetic diversity between populations, clearly discriminating between populations of North American and European origin, and also between European populations. NAM had the lowest effective population size, followed by SCO and NOR. Large differences in the LD decay were observed between populations of North American and European origin. An r 2 threshold of 0.2 was estimated for marker pairs separated by 7,800, 64, and 50 kb in the NAM, SCO, and NOR populations, respectively. In this study we show that this SNP panel can be used to detect association between markers and traits of interests and also to capture high-resolution information for genome-enabled predictions. Also, we suggest the feasibility to achieve similar prediction accuracies using a smaller SNP data set for the NAM population, compared with samples with European origin which would need a higher density SNP array.
RESUMO
Alcohol use disorders are modulated by genetic factors, but the identification of specific genes and their concomitant biological changes that are associated with a higher risk for these disorders has proven difficult. Alterations in the sensitivity to the motivational effects of ethanol may be one way by which genes modulate the initiation and escalation of ethanol intake. Rats and mice have been selectively bred for high and low ethanol consumption during adulthood. However, selective breeding programs for ethanol intake have not focused on adolescence. This phase of development is associated with the initiation and escalation of ethanol intake and characterized by an increase in the sensitivity to ethanol's appetitive effects and a decrease in the sensitivity to ethanol's aversive effects compared with adulthood. The present study performed short-term behavioral selection to select rat lines that diverge in the expression of ethanol drinking during adolescence. A progenitor nucleus of Wistar rats (F0) and filial generation 1 (F1), F2, and F3 adolescent rats were derived from parents that were selected for high (STDRHI) and low (STDRLO) ethanol consumption during adolescence and were tested for ethanol intake and responsivity to ethanol's motivational effects. STDRHI rats exhibited significantly greater ethanol intake and preference than STDRLO rats. Compared with STDRLO rats, STDRHI F2 and F3 rats exhibited a blunted response to ethanol in the conditioned taste aversion test. F2 and F3 STDRHI rats but not STDRLO rats exhibited ethanol-induced motor stimulation. STDRHI rats exhibited avoidance of the white compartment of the light-dark box, a reduction of locomotion, and a reduction of saccharin consumption, suggesting an anxiety-prone phenotype. The results suggest that the genetic risk for enhanced ethanol intake during adolescence is associated with lower sensitivity to the aversive effects of ethanol, heightened reactivity to ethanol's stimulating effects, and enhanced innate anxiety.