ABSTRACT In the last decade, other quality attributes have emerged as the main aspects that impact pork consumers acceptance, such as environmentally friendly production, nutritional value, and animal welfare. This study applies a Check-All-That-Apply (CATA) questionnaire for sensory characterization of loins from genetically lean immunocastrated male pigs fed diets containing either a standard commercial diet with 1.5 % soybean oil (control) or 3 % oil from either soybean oil (SO), canola oil (CO), or fish oil (FO) during the growing-finishing phases. Twenty CATA attributes for loin samples were generated. We interviewed 101 consumers to select all the CATA terms that they considered suitable to characterize sensory attributes of longissimus lumborum muscle samples of pigs from each dietary treatment. The CATA results indicated differences among pork loin samples depending on the source and inclusion level of dietary oil. Loins from pigs fed 3 % SO were characterized by a higher frequency of the “juicy texture” attribute (p < 0.05) and a lower frequency of the “dry texture” attribute (p < 0.05) compared to loins from 3 % FO-fed pigs. Moreover, loins from pigs fed 3 % SO had a lower citation frequency of the “tasteless” attribute (p < 0.05) compared to loins from 3 % FO-fed pigs. The attributes “cooked pork meat-like taste”, “juicy texture”, “tender texture”, and “brightness” were placed close to the overall liking. “Tender texture”, “juicy texture”, “pork meat-like” (odor and taste), and “cooked pork meat-like taste” attributes were considered drivers of liking. Feeding genetically lean immunocastrated male pigs with diets containing 3 % SO may be advisable from a pork sensory quality perspective.

Resumo Uma vez que o sistema calpaína é central para o amaciamento da carne e dada a importância da atividade de calpastatina na determinação da maciez de bifes de bovinos Bos taurus indicus, o objetivo do presente estudo foi determinar se a expressão do gene de μ-calpaína (CAPN1), calpastatina total (CAST T), e suas variantes (CAST I e II) foi induzido pela inclusão de vitamina D3 na dieta. Os animais receberam nenhuma ou 2 × 106 UI dose de vitamina D3 por 2 ou 8 dias antes do abate, e foram submetidos a diferentes condições durante o confinamento: exposição solar ou sombreamento artificial. Bifes do Longissimus lumborum foram fabricados e submetidos a maturação por 1, 7, e 21 dias post-mortem e posteriormente usados para determinação da força de cisalhamento e do índice de fragmentação miofibrilar. Vitamina D3 não influenciou a abundância de RNAm, exceto para maior abundância de transcritos de CAST II em animais que foram suplementados por 8 dias antes do abate. Foi encontrada associação negativa entre a abundância de CAST II e a força de cisalhamento. Essa contradição revela uma importante modulação da expressão do sistema calpaína resultado da suplementação com vitamina D que pode ser importante na determinação de estratégias para melhorar a maciez da carne.

ABSTRACT The calpain system is the central player for meat tenderization and the calpastatin activity plays an important role in beef tenderness of Bos taurus indicus cattle. This study investigated whether dietary vitamin D3 induced gene expression of μ-calpain (CAPN1), total calpastatin (CAST T), and their variants (CAST I and II). Animals received none or 2 × 106 IU of vitamin D3 for either 2 or 8 days before slaughter and were submitted to different conditions during feedlot: sun exposure or artificial shade. Steaks from Longissimus lumborum were fabricated, aged for 1, 7, and 21 days post-mortem, and later used for the analyses of shear force and the myofibrillar fragmentation index. Vitamin D3 did not influence mRNA abundance; however, it induced a greater CAST II transcript in animals supplemented 8 days before slaughter. There was a negative association between CAST II abundance and the shear force, which revealed an important modulation of the calpain system expression due to vitamin D supplementation. This result is an important tool for strategies to improve beef tenderness.

ABSTRACT: Growth hormone (GH), insulin-like growth factor 1 (IGF1), and leptin (LEP) can be candidate genes for association studies because they play vital roles in the metabolism process. Thus, this study aimed to identify variants in these genes associated with body traits in Santa Inês sheep. The following were recorded: body weight at 100 (BW100) and 240 days (BW240), average daily gain (ADG), withers (WH) and croup (CH) heights, body length (BL), thoracic (TG) and leg (LG) girths, thoracic (TW) and croup (CW) widths, body depth (BD), rib eye area (REA), fat thickness (FT), and carcass finishing score (CFS). Single-locus association analysis was performed with 11 variants in IGF1, 18 in LEP, and 16 in GH. Moreover, two haplotypes in IGF1 and one haplotype in LEP were evaluated in haplotype association analysis. The single-locus analysis revealed 23 suggestive additive effects (p < 0.05), but no additive effect was found at the Bonferroni threshold. Haplotype association analysis revealed 19 additive effects, of which ten were at the Bonferroni threshold (p < 0.0074). In IGF1 gene, haplotype replacements were associated with ADG 20.51(7.37), CH 4.09(1.21), WH 3.52(1.20), BL 3.94(1.19), TG 3.88(1.30), TW 1.13(0.36), and LG 3.40(1.08); while in the LEP gene the haplotype replacement was associated with BW100 1.83(0.51), BD −2.51(0.56), and CFS −0.24(0.06). Therefore, there are haplotypes in IGF1 and LEP genes associated with body traits in Santa Inês sheep, which can be useful in marker-assisted selection.

Resumo: O objetivo deste trabalho foi sequenciar os genes MyoD1, MyoG, MyF5, MyF6 e MSTN e identificar polimorfismos em ovinos Santa Inês (Ovis aries). No total, 192 cordeiros com 240 dias de idade foram avaliados, e estes genes foram sequenciados para comparação com a sequência-referência no genoma de Ovis aries. As frequências genotípicas e alélicas foram estimadas, e o equilíbrio de Hardy-Weinberg, testado. Foram obtidos fragmentos contendo 2.493 pb (MyoDl), 1.836 pb (MyoG), 2.813 pb (MyF5), 1.126 pb (MyF6) e 2.380 pb (MSTN), e, nessas sequências, foram identificadas 160 variantes. Esses polimorfismos foram distribuídos da seguinte forma: 59 (MyoD1), 24 (MyoG), 63 (MyF5), 4 (MyF6) e 10 (MSTN). Foram encontrados 104 novos polimorfismos, sendo 45 no MyoD1, 2 no MyoG, 56 no MyF5 e 1 no MSTN. Com relação ao local, 61 variantes estavam em íntron (27 no MyoD1, 16 no MyoG, 5 no MyF5, 3 no MyF6 e 10 no MSTN), 87 em região codificante (22 no MyoD1, 8 no MyoG, 56 no MyF5 e 1 no MyF6) e 12 na região 3’UTR (10 no MyoD1 e 2 no MyF5). Portanto, os genes da família MyoD e o MSTN possuem vários polimorfismos em ovinos da raça Santa Inês, os quais podem ser úteis em estudos de associação.

Abstract: The objective of this work was to sequence the MyoD1, MyoG, MyF5, MyF6, and MSTN genes and to identify polymorphisms in Santa Inês sheep (Ovis aries). A total of 192 lambs with 240 days of age were evaluated, and these genes were sequenced to be compared with the reference sequence in the Ovis aries genome. Genotype and allele frequencies were estimated, and the Hardy-Weinberg equilibrium was tested. Fragments containing 2,493 bp (MyoD1), 1,836 bp (MyoG), 2,813 bp (MyF5), 1,126 bp (MyF6), and 2,380 bp (MSTN) were obtained, and, in these sequences, 160 variants were identified. These polymorphisms were distributed as follows: 59 (MyoD1), 24 (MyoG), 63 (MyF5), 4 (MyF6), and 10 (MSTN). One hundred and four were novel polymorphisms, 45 in MyoD1, 2 in MyoG, 56 in MyF5, and 1 in MSTN. Regarding site, 61 were in intron (27 in MyoD1, 16 in MyoG, 5 in MyF5, 3 in MyF6, and 10 in MSTN), 87 in coding region (22 in MyoD1, 8 in MyoG, 56 in MyF5, and 1 in MyF6), and 12 on 3’UTR (10 in MyoD1 and 2 in MyF5). Therefore, the MyoD family and MSTN genes have several polymorphisms in Santa Inês sheep, which can be useful for association studies.

O objetivo deste trabalho foi caracterizar genotipicamente, e construir o mapa de ligação e mapear locos associados a características quantitativas (QTL) de desempenho e carcaça no cromossomo 5 de linhagens brasileiras galinhas. Utilizou-se uma população F2 CTCT, resultante do acasalamento entre machos da linhagem de postura CC e fêmeas da linhagem de corte TT. Um total de 356 animais foi genotipado com 11 marcadores microssatélites. A caracterização genotípica foi realizada pela estimação dos seguintes parâmetros genotípicos: conteúdo de informação polimórfica (0,45-0,69), heterozigosidades observada (0,48-1,00) e esperada (0,48-0,74), e número de alelos por loco (3-5). Empregou-se o mapeamento por intervalo combinado à modelagem fenotípica por modelo misto, no mapeamento de QTL. O comprimento do mapa de ligação foi de 174,7 cM. Não foram constatadas inversões entre o mapa obtido, o mapa consenso e o genoma. Foram mapeados nove QTL, dos quais sete foram sugestivos ("log of odds", LOD<1,5) e dois significativos ao nível cromossômico (LOD>3,0). Seis destes QTL são inéditos: conversão alimentar e eficiência alimentar dos 35 aos 41 dias de idade (significativo), pesos de cabeça e fígado, e triglicerídeos e triglicerídeos+colesterol. A população CTCT apresenta variabilidade genotípica, o mapa de ligação é similar ao mapa consenso e ao genoma, e novos QTL foram mapeados.

The objective of this work was to genotype, construct the linkage map and map quantitative trait loci (QTL) associated with performance and carcass on chromosome 5 of Brazilian chickens lines. It was used a F2 CTCT chicken population, resulting from the crossing of males from a CC layer line with females from a TT broiler line. A total of 356 animals were genotyped with 11 microsatellite markers. Genotypic characterization was carried out by the estimation of the following genotypic parameters: polymorphic information content (0.45-0.69), observed (0.48-1.00) and expected (0.48-0.74) heterozygosities, and number of alleles per locus (3-5). QTLmapping used interval mapping combined with phenotypic modeling via mixed model. The length of the linkage map was 174.7 cM. No inversions were found between the obtained map, the consensus map, and the genome. Nine QTL were mapped, of which seven were suggestive (log of odds, LOD<1.5) and two significant at the chromosome level (LOD>3.0). Six of these QTL are original: feed conversion and feed efficiency from 35 to 41 days of age (significative), weight of head and liver, and triglycerides and triglycerides+cholesterol. The CTCT population shows genotypic variability, the linkage map is similar to consensus map and genome, and new QTL were mapped.

Este estudo teve por objetivo mapear QTL (quantitative trait loci) utilizando combinações lineares de características de interesse econômico em Gallus gallus. Foram estudadas 350 aves F2 oriundas de um cruzamento inicial entre machos de uma linhagem de corte (TT) e fêmeas de uma linhagem de postura (CC). Foi conduzido mapeamento de QTL nos cromossomos Gallus gallus (GGA1, GGA3, GGA5, GGA8, GGA11 e GGA13), para 20 características de desempenho e de carcaça. Para detectar QTL foi utilizado o teste da razão de verossimilhanças entre um modelo reduzido (incluindo efeitos fixos de sexo, incubação e o efeito aleatório de valor genético infinitesimal) e um completo (incluindo todos os efeitos anteriores mais os efeitos de QTL). Ao analisar as características originais, ou seja, antes da formação das combinações lineares, foram mapeados seis QTLs significativos a 1% no genoma, quatro no GGA1 (peso vivo aos 35 dias, peso vivo aos 42 dias, gordura abdominal e peso do coração) e dois no GGA3 (peso vivo aos 35 e aos 42 dias de idade); três QTLs significativos a 5% no genoma, sendo um no GGA1 (peso da cabeça), um no GGA3 (peso das asas), e um no GGA8 (peso da moela); além de sete ligações sugestivas para diversas características. Ao mapear QTLs para os componentes principais, foram confirmados vários QTLs mapeados para as características originais, além de encontrar três QTLs e oito ligações sugestivas não mapeadas para as características originais.

This study aimed at mapping QTL (quantitative trait loci) using linear combinations of characteristics of economical interest in Gallus gallus. A total of 350 F2 chickens from an initial crossing among males from a broiler line (TT) with females from a layer line (CC) were used. It was conducted a QTL mapping in chromosomes of Gallus gallus (GGA1, GGA3, GGA5, GGA8, GGA11, and GGA13) for 20 performance and carcass traits. For detecting QTL, it was used the likelihood ratio test between a reduced model (including fixed effects of sex, hatch and random effect of infinitesimal genetic value) and a full model (including all the previous effects plus QTL effects). When original characterists were analyzed, that is, before the formation of linear combinations, six significant QTLs were mapped at 1% in the genome, four in the GGA1 (live weight at 35 days of age and at 42 days of age, abdominal fat and heart weight); and two on GGA3 (live weight at 35 and 42 days of age); three significant QTLs at 5% in the genome, one on GGA1 (head weight), one on GGA3 (wings weight), and one on GGA8 (gizzard weight); besides seven suggestive linkages for several traits. When QTLs were mapped for principal components, many mapped QTLs were confirmed for original traits, in addition to finding three QTLs and eight suggestive linkages not mapped for the original traits.

A biotecnologia animal tem fornecido novas ferramentas para os programas de melhoramento e, dessa forma, contribuído para melhorar a eficiência da produção dos produtos de origem animal. No entanto, os avanços têm sido mais lentos do que antecipados, especialmente em razão da dificuldade na identificação dos genes responsáveis pelas características fenotípicas de interesse zootécnico. Três estratégias principais têm sido utilizadas para identificar esses genes - mapeamento de QTL, genes candidatos e sequenciamento de DNA e mRNA - e cada uma tem suas vantagens e limitações. O mapeamento de QTL permite determinar as regiões genômicas que contêm genes, mas o intervalo de confiança do QTL pode ser grande e conter muitos genes. A estratégia de genes candidatos é limitada por causa do conhecimento ainda restrito das funções de todos os genes. Os sequenciamentos de genomas e de sequências expressas podem auxiliar na identificação da posição de genes e de vias metabólicas associadas à característica de interesse. A integração dessas estratégias por meio do desenvolvimento de programas de bioinformática permitirá a identificação de novos genes de interesse zootécnico. Assim, os programas de melhoramento genético se beneficiarão pela inclusão da informação obtida diretamente do DNA na avaliação do mérito genético dos plantéis disponíveis.

Animal biotechnology is providing new tools for animal breeding and genetics and thus contributing to advances in production efficiency and quality of animal products. However, the progress is slower than anticipated, mainly because of the difficulty involved in identifying genes that control phenotypic characteristics of importance to the animal industry. Three main strategies: QTL mapping, candidate genes and DNA and mRNA sequencing have been used to identify genes of economic interest to animal breeding and each has advantages and disadvantages. QTL mapping allows identification of the genomic region that contains the genes, but the confidence interval of the regions is usually large and may contain several genes. Candidate gene approach is limited to our restricted knowledge of the biological function of the genes. Sequencing of genomes and expressed sequences tags can provide identifying gene position and metabolic pathways associated with phenotypic trait. Integrating these strategies using bioinformatics software will allow identifying of novel genes for animal production. Then, animal breeding programs will include the information from DNA directly on evaluation of genetic value of livestock production.

Precise normalization with reference genes is necessary, in order to obtain reliable relative expression data in response to gastrointestinal nematode infection. By using sheep from temperate regions as models, three reference genes, viz., ribosomal protein LO (RPLO), glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and succinate dehydrogenase complex subunit A (SDHA), were investigated in the abomasum, abomasal lymph nodes and small intestine of Brazilian Somalis sheep, either resistant or susceptible to gastrointestinal nematodes infections. Real time PCR was carried out by using SYBR Green I dye, and gene stability was tested by geNorm. RPLO was an ideal reference gene, since its expression was constant across treatments, presented lower variation, and was ranked as the most stable in abomasum and lymph node tissues. On the other hand, SDHA was the most stable in the small intestine followed by RPLO and GAPDH. These findings demonstrate the importance of correctly choosing reference genes prior to relative quantification. In addition, we determined that reference genes used in sheep from temperate regions, when properly tested, can be applied in animals from tropical regions such as the Brazilian Somalis sheep.

Amostras do músculo Pectoralis major foram coletadas e uma RT-PCR foi conduzida para avaliar a sequência do mRNA do αRYR, região compreendida entre os resíduos de aminoácido 386-540, numerado de acordo com a sequência de perus. Os resultados revelaram duas classes de transcritos. O primeiro teve 97% e 74% de identidade com as sequências de αRyR e RyR1 de perus e humanos, respectivamente, e incluiu todos os transcritos com substituições de nucleotídeos. A segunda classe de transcritos foi caracterizada pela deleção de bases que levaram a um stop códon prematuro e a uma proteína truncada não-funcional. Esses resultados são até o momento, o primeiro relato de sequenciamento do αRYR, região hotspot1 de frangos e podem servir como guia para estudos futuros na tentativa de se encontrar uma solução para os problemas na cadeia de produção de frangos relacionados com as carnes PSE (pálida, flácida e exsudativa).

Samples of Pectoralis major m. were collected, and an RT-PCR analysis of the a-Ryanodine receptor (a RYR) from chicken mRNA hotspot region spanning aminoacid residues 386 to 540, numbered according to the turkey sequence, revealed two classes of transcripts. The sequences of the first class were similar to turkey and human with 97% and 74% of identity, respectively, and included all transcripts with substitutions in the nucleotide sequence. The second class was characterized by the deletion of nucleotides, leading to a premature stop codon and coding for a truncated and nonfunctional protein. These results are to date the first report related to the sequencing of the chicken αRYR hotspot region 1, which will possibility serve as a guide for further studies regarding a solution in the poultry production chain related to the problem of pale, soft and exudative (PSE) meat.

Populações experimentais de frangos tem sido desenvolvidas pelo mundo para mapeamento de QTLs, mas a caracterização genotípica delas não é normalmente apresentada. O objetivo deste estudo foi caracterizar genotipicamente duas gerações F1 recíprocas e suas linhagens parentais com base na estimação de parâmetros genotípicos. Estas gerações F1 originaram duas populações brasileiras referências para mapear QTLs. Os parâmetros avaliados foram: conteúdo de informação polimórfica (PIC), heterozigosidades observada e esperada e número de alelos por loco nos cromossomos 1, 3 e 4. Todos os animais parentais e F1 de ambas as populações foram usados, em um total de 83 animais: 14 de uma linhagem de corte (TT) e 14 de uma linhagem de postura (CC), e 55 de suas gerações recíprocas F1. Tanto as linhagens como as populações referências foram desenvolvidas no Centro Nacional de Pesquisa de Suínos e Aves (EMBRAPA), Brasil. Os genótipos de todos os animais foram obtidos a partir de 34 marcadores microssatélites localizados nos cromossomos 1 (13), 3 (12) e 4 (9). Com base na amostragem realizada, as duas linhagens exibiram um total de 163 alelos, dos quais 31 (31,1%) e 44 (33,0%) foram oriundos exclusivamente de CC e TT, respectivamente, com freqüências alélicas que variaram de 0,03 a 0,82. A heterozigosidade observada foi maior (0,68-0,71) em ambas as gerações F1 do que em suas linhagens fundadoras devido ao desequilíbrio de ligação. Finalmente, as duas linhagens parentais possibilitaram a obtenção de gerações recíprocas F1 com valores elevados de PIC (0,50-0,52) e heterozigosidade observada, bem como com um número satisfatório de alelos por loco (4,06-4,32). Estes resultados permitirão comparar e selecionar famílias e marcadores microssatélites mais informativos em estudos de QTLs, reduzindo os custos de genotipagem.

Chicken experimental populations have been developed worldwide for QTL mapping, but their genotypic characterizations are not usually discussed. The objective of this study was to characterize genotypically two F1 reciprocal generations and their parental lines based on the estimation of genotypic parameters. These F1 generations originated two Brazilian reference populations to map QTL. The evaluated parameters were polymorphic information content (PIC), observed and expected heterozygosities and number of alleles at microsatellite loci on chromosomes 1, 3 and 4. All parental and F1 chickens from both populations were used totalling of 83 chickens: 14 from a broiler (TT) and 14 from a layer line (CC) and 55 from their reciprocal F1 generations. The chicken lines and the resource populations were developed at the National Research Center for Swine and Poultry (EMBRAPA), Brazil. Genotypes from all animals were obtained from 34 loci on chromosomes 1 (13), 3 (12) and 4 (9). Based on the sampling, we found that the two lines exhibited a total of 163 different alleles, of which 31 (31.1%) and 44 (33.0%) alleles were unique in CC and TT lines, respectively, with allelic frequencies ranging from 0.03 to 0.82. The observed heterozygosity was higher (0.68-0.71) in both F1 generations than in their founder lines due to linkage disequilibrium. Finally, the two chicken lines used as founders created two F1 reciprocal generations with high levels of PIC (0.50-0.52) and observed heterozygosity, as well as satisfactory number of alleles per locus (4.06-4.32). Our results will allow to compare and select families with highly informative microsatellite markers for QTL studies, reducing genotyping costs.

Fatores de crescimento coordenam múltiplas vias de sinalização durante o desenvolvimento embrionário. Neste estudo, a abundância de mRNA dos genes IGF-II e bFGF foi estimada em embriões de galinha por análises de RT-PCR competitiva. Aumentos na abundância de mRNA de IGF-II foram observados nos estádios HH1, 5. Os níveis de mRNA de bFGF exibiram aumentos a partir dos estádios HH18 e 20, seguido por uma acentuada redução a níveis basais no estádio HH24 e por um segundo pico na expressão destes transcritos no estádio HH26. Tais descobertas proporcionam importantes informações sobre o padrão de expressão destes fatores de crescimento durante a embriogênese de aves

In this study, the abundance of IGF-II and bFGF transcripts was estimated in the chicken embryos using the competitive RT-PCR analysis. Significant enhancements in the abundance of IGF-II mRNA were observed at stages HH1 and 5, and a new accumulation in these levels was observed at stage HH18 in comparison to the basal levels. The abundance of bFGF mRNA increased significantly at stages HH18 and 20, followed by an upregulation in the expression of these transcripts at stage HH26. These findings provided important information about the temporal expression pattern of IGF-II and bFGF transcripts in the whole chicken embryos during in ovo development.

A leptina, hormônio polipeptídico secretado principalmente pelo tecido adiposo, tem um papel importante na regulação da ingestão de alimentos, metabolismo de energia e reprodução em mamíferos. A função do gene da leptina tem sido intensamente estudada em mamíferos, porém, em aves, ainda é pouco conhecida. O cDNA deste gene foi identificado em galinhas, e a alta expressão hepática e os níveis de leptina no plasma foram associados à alta deposição de gordura presente em linhagens de aves selecionadas. Entretanto, permanecem controvérsias sobre o gene da leptina em galinhas, pois diversos autores não conseguiram amplificar este gene a partir de DNA genômico ou cDNA. Tendo em vista essas controvérsias e a importância desse gene, o presente trabalho teve como objetivo amplificar o gene da leptina numa população de aves desenvolvida pela Embrapa Suínos e Aves (Brasil). Primeiramente, as seqüências do gene da leptina de Gallus gallus (GenBank AF012727) e Mus musculus (GenBank NM_008493) foram alinhadas com o objetivo de desenhar os primers em regiões conservadas nas duas espécies, pois como descrito na literatura, esses genes apresentam 94,6% de similaridade. Para os quatro pares de primers desenhados, foram realizados diversos testes de amplificação utilizando DNA e cDNA, mas não foi obtido um fragmento único ou a banda esperada. A seqüência do gene da leptina depositada no GenBank não representa a seqüência do gene da leptina de galinhas.

Leptin, a polypeptide hormone secreted mainly by adipose tissue, plays an important role in feed intake regulation, energy metabolism and reproduction in several species. Its function has been intensively studied in mammals; however, in birds limited information is available. The cDNA sequence for chicken leptin has been reported, and high hepatic expression levels of leptin were associated with fat deposition in selected bird lines. However, controversies still remain concerning to the chicken leptin gene and several authors failed to amplify this gene from genomic DNA or cDNA. In view of this controversy and the importance of this gene, the present study aimed to investigate the leptin gene in a population of birds developed by Embrapa Swine and Poultry Research Center (Brazil). First of all, the sequences of Gallus gallus leptin gene (GenBank AF012727) and Mus musculus (GenBank NM_008493) were aligned with the objective of designing primers in conserved regions among the two species, since 94.6% of similarity is described in the literature in those species. For all four pairs of primers designed, several amplification tests were performed with both DNA and cDNA, but neither unique fragment nor expected band size was ever achieved. The leptin sequence in GenBank does not represent the sequence of the chicken leptin gene.

O mapa de ligação além de ser fundamental no mapeamento de locos de características quantitativas (QTLs) é importante na organização e localização de genes distribuídos ao longo dos cromossomos. O presente estudo é parte de um trabalho cujo objetivo maior, é a análise de mapeamento de QTLs para características de desempenho no genoma de uma população experimental desenvolvida no Brasil. Com base nesta população foram construídos os mapas de ligação dos cromossomos 6 a 8, 11 e 13 da galinha. A população foi desenvolvida a partir de duas gerações de cruzamentos entre uma linhagem de corte e uma de postura. Foram testados 51 marcadores microssatélites, dos quais 28 foram informativos: 4, 8, 7, 4 e 5 dos cromossomos 6, 7, 8, 11 e 13, respectivamente. Um SNP localizado no gene do receptor da leptina foi incluído no cromossomo 8. Os 10 parentais, 8 F1 e um total de 459 aves F2 de cinco famílias de irmãos completos foram genotipados com estes marcadores. O número de meioses informativas totais por loco variou de 232 a 862 e o de meioses informativas de fase conhecida de 0 a 764. A ordem dos marcadores nos cromossomos coincidiu com a do mapa consenso da galinha, com exceção dos marcadores ADL0147 e MCW0213 do cromossomo 13 que tiveram sua ordem invertida. O número reduzido de meioses informativas de fase conhecida para o marcador ADL0147 (150) pode ser apontado como uma possível causa para a inversão, além da relativa proximidade entre os dois marcadores envolvidos na inversão (10,5 cM).

A linkage map is essential not only for quantitative trait loci (QTL) mapping, but also for the organization and location of genes along the chromosomes. The present study is part of a project whose major objective is, besides from construction the linkage maps, the whole genome scan for mapping QTL for performance traits in the Brazilian experimental chicken population. Linkage maps of chicken chromosomes 6 to 8, 11 and 13 were constructed based on this population. The population was developed from two generations of crossbreeding between a broiler and a layer line. Fifty-one microsatellite markers were tested, from which 28 were informative: 4, 8, 7, 4 and 5 for chromosomes 6, 7, 8, 11 and 13, respectively. A SNP located in the leptin receptor gene was included for chromosome 8. Ten parental, 8 F1 and 459 F2 chickens from five full-sib families were genotyped with these markers. The number of total informative meioses per locus varied from 232 to 862, and the number of phase-known informative meioses from 0 to 764. Marker orders in the chromosomes coincided with those of the chicken consensus map, except for markers ADL0147 and MCW0213, on chromosome 13, which were inverted. The reduced number of phase-known informative meioses for ADL0147 (150) may be pointed out as a possible cause for this inversion, apart from the relative short distance between the two markers involved in the inversion (10.5 cM).

Quantitative trait loci (QTL) mapping in livestock allows the identification of genes that determine the genetic variation affecting traits of economic interest. We analyzed the birth weight and weight at 60 days QTL segregating on bovine chromosome BTA14 in a F2 resource population using genotypes produced from seven microsatellite markers. Phenotypes were derived from 346 F2 progeny produced from crossing Bos indicus Gyr x Holstein Bos taurus F1 parents. Interval analysis to detect QTL for birth weight revealed the presence of a QTL (p < 0.05) at 1 centimorgan (cM) from the centromere with an additive effect of 1.210 ± 0.438 kg. Interval analysis for weight at 60 days revealed the presence of a QTL (p < 0.05) at 0 cM from the centromere with an additive effect of 2.122 ± 0.735 kg. The region to which the QTL were assigned is described in the literature as responsible for some growth traits, milk yield, milk composition, fat deposition and has also been related to reproductive traits such as daughter pregnancy rate and ovulation rate. The effects of the QTL described on other traits were not investigated.

Brazilian poultry industry has reached a high level of development in both meat and egg production as a result of constant technological modernization. Further improvements can be achieved through genomics, but before this can be accomplished, a better understanding of gene expression profiles and nucleotide polymorphisms is necessary. Since animal physiology is directly or indirectly controlled by the pituitary and hypothalamus, the aim of the present work was to identify and analyze genes expressed in these tissues in chicken lines with different growth potential. Two pituitary and hypothalamus cDNA libraries from 21 day broiler (TT) and layer (CC) chickens lines were constructed and allowed identification of 3,074 unique sequences and 77 single nucleotide polymorphisms (SNPs). The collection of expressed sequence tags (ESTs) and SNPs identified in this study represents an important resource for future studies aimed at identifying genes responsible for growth in chicken.