RESUMO
It has been demonstrated that variations in litter size or ovulation rate in different breeds of sheep can be associated with the segregation of several major genes. This set of natural mutants constitutes a valuable resource to determine key points in the biochemical pathways controlling the development of ovarian follicles. The French genetic programmes were devised to identify two of these genes: the Booroola (FecB) and Lacaune genes. The FecB prolific mutation corresponds to a non-conservative mutation (Q249R) in the intracellular kinase-signalling domain of the bone morphogenetic protein receptor type IB (BMPR-IB) gene. The Lacaune gene is situated on ovine chromosome 11. Positional cloning is currently in progress to identify the relevant gene and mutation. A similar approach, limited to linkage testing of candidate genes, is proposed to classify the different prolificacy genes in sheep.
Assuntos
Tamanho da Ninhada de Vivíparos/genética , Reprodução/genética , Ovinos/genética , Animais , Receptores de Proteínas Morfogenéticas Ósseas Tipo I , Cruzamento , Mapeamento Cromossômico , Feminino , França , Genótipo , Masculino , Ovulação/genética , Mutação Puntual , Proteínas Serina-Treonina Quinases/genética , Receptores de Fatores de Crescimento/genéticaRESUMO
For the first time, an Escherichia coli strain producing four microcins (Mcc), B17, D93, J25, and L, and showing immunity to Mcc V was isolated and characterized. Each of the gene clusters encoding the production of Mcc B17, D93, and L was cloned separately. The gene cluster for Mcc L was cloned within a 13.5-kb HindIII-SalI fragment, which includes the Mcc V immunity gene, cvi.
Assuntos
Bacteriocinas/biossíntese , Bacteriocinas/genética , Clonagem Molecular , Escherichia coli/genética , Genes Bacterianos , Bacteriocinas/imunologia , Bacteriocinas/farmacologia , Farmacorresistência Bacteriana , Escherichia coli/imunologia , Escherichia coli/isolamento & purificação , Escherichia coli/metabolismo , Testes de Sensibilidade Microbiana , Dados de Sequência MolecularRESUMO
Ewes from the Booroola strain of Australian Mérino sheep are characterized by high ovulation rate and litter size. This phenotype is due to the action of the FecB(B) allele of a major gene named FecB, as determined by statistical analysis of phenotypic data. By genetic analysis of 31 informative half-sib families from heterozygous sires, we showed that the FecB locus is situated in the region of ovine chromosome 6 corresponding to the human chromosome 4q22-23 that contains the bone morphogenetic protein receptor IB (BMPR-IB) gene encoding a member of the transforming growth factor-beta (TGF-beta) receptor family. A nonconservative substitution (Q249R) in the BMPR-IB coding sequence was found to be associated fully with the hyperprolificacy phenotype of Booroola ewes. In vitro, ovarian granulosa cells from FecB(B)/FecB(B) ewes were less responsive than granulosa cells from FecB(+)/FecB(+) ewes to the inhibitory effect on steroidogenesis of GDF-5 and BMP-4, natural ligands of BMPR-IB. It is suggested that in FecB(B)/FecB(B) ewes, BMPR-IB would be inactivated partially, leading to an advanced differentiation of granulosa cells and an advanced maturation of ovulatory follicles.
Assuntos
Mutação/genética , Ovulação/genética , Receptores de Superfície Celular/genética , Receptores de Fatores de Crescimento , Ovinos/genética , Ovinos/fisiologia , Sequência de Aminoácidos , Substituição de Aminoácidos/genética , Animais , Austrália , Sequência de Bases , Proteína Morfogenética Óssea 4 , Receptores de Proteínas Morfogenéticas Ósseas , Proteínas Morfogenéticas Ósseas/farmacologia , Cromossomos Humanos Par 4/genética , Feminino , Fertilidade/genética , Células da Granulosa/efeitos dos fármacos , Células da Granulosa/metabolismo , Fator 5 de Diferenciação de Crescimento , Substâncias de Crescimento/farmacologia , Heterozigoto , Humanos , Tamanho da Ninhada de Vivíparos/genética , Masculino , Modelos Moleculares , Dados de Sequência Molecular , Fenótipo , Mapeamento Físico do Cromossomo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Receptores de Superfície Celular/química , Receptores de Superfície Celular/metabolismo , Alinhamento de SequênciaAssuntos
Cromossomos Humanos Par 13 , Conexinas/genética , Displasia Ectodérmica/genética , Mutação de Sentido Incorreto , Sequência de Aminoácidos , Substituição de Aminoácidos , Animais , Arginina , Mapeamento Cromossômico , Conexina 30 , Feminino , Glicina , Humanos , Masculino , Camundongos , Dados de Sequência Molecular , Linhagem , Alinhamento de Sequência , Homologia de Sequência de AminoácidosRESUMO
The HED (hidrotic ectodermal dysplasia) or Clouston syndrome gene (named ED2) has been mapped to the pericentromeric region of chromosome 13 (13q11) to a 2.4-cM interval flanked by markers D13S1828 and D13S1830. We have developed a BAC/PAC-based contig map of this region. This contig, comprising 23 clones and spanning 1.5 Mb, was established by mapping of 27 BAC/PAC end-derived STSs, 11 known polymorphic markers, 2 previously mapped genes, and 14 ESTs. The genomic clone overlaps were confirmed by restriction fragment fingerprint analysis. This contig provides the basis for genomic sequencing and gene identification in the ED2 critical region. Of the 14 ESTs mapped to the contig, 6 show homology to human genes and 8 appear to be novel. Expression patterns of the genes/ESTs were tested by Northern blot and RT-PCR. Full characterization of some of these genes, as well as the novel ESTs, will be useful in assessing their involvement in the HED/Clouston syndrome.
Assuntos
Cromossomos Humanos Par 13/genética , Displasia Ectodérmica/genética , Mapeamento Físico do Cromossomo , Mapeamento de Sequências Contíguas , Etiquetas de Sequências Expressas , Humanos , Repetições de Microssatélites , Sitios de Sequências RotuladasRESUMO
Direct amplification of length polymorphisms (DALP) uses an arbitrarily primed PCR (AP-PCR) to produce genomic fingerprints and to enable sequencing of DNA polymorphisms in virtually any species. Oligonucleotide pairs were designed to each produce a specific multi-banded pattern and all the fragments thus generated can be directly sequenced with the same two universal M13 sequencing primers. This strategy combines the advantages of a high resolution fingerprint technique and the possibility of characterizing the polymorphisms. The use of family members as templates in the multi-locus detection step allows a direct test of allele transmission, as well as early mapping of the markers or selection of loci associated with some traits or diseases. We used this method to detect micro-deletions/insertions and microsatellite DNA loci useful in population genetics studies, but it could be applied in many other fields of biology, such as genome mapping for definition of polymorphic sequence tagged sites, directly localized on a genetic map.
Assuntos
Marcadores Genéticos , Técnicas de Amplificação de Ácido Nucleico , Polimorfismo Genético , Animais , Bacteriófago lambda/genética , Sequência de Bases , Mapeamento Cromossômico , Primers do DNA/genética , DNA Satélite/genética , DNA Viral/genética , Estudos de Avaliação como Assunto , Genoma , Camundongos , Mutação , Reação em Cadeia da Polimerase/métodos , Sitios de Sequências Rotuladas , Especificidade da EspécieRESUMO
The ovine map is not yet well-developed, which represents a problem when looking for markers of a region of interest in sheep. A means of circumventing this is to use comparative mapping. In this study primers were determined using consensus sequences for the epidermal growth factor gene of humans, rats and mice, and an ovine epidermal growth factor gene fragment was amplified by polymerase chain reaction (PCR). A new set of specific ovine primers was chosen to study the polymorphism of this DNA fragment by denaturing gradient gel electrophoresis. Eighty-four individuals belonging to seven sheep breeds were studied with this technique and four alleles were detected. The heterozygosity rate was 0.57. Family analysis showed mendelian inheritance of the alleles. Usually, genetic analysis of type-I loci used in the comparative mapping is based on the detection of restriction fragment length polymorphisms in sheep DNA using cDNA probes from other species. Our work shows that another method, based on PCR and denaturing gradient gel electrophoresis techniques, can be efficiently used.
Assuntos
Eletroforese em Gel de Poliacrilamida/métodos , Fator de Crescimento Epidérmico/genética , Reação em Cadeia da Polimerase/métodos , Polimorfismo Genético , Ovinos/genética , Animais , Sequência de Bases , Primers do DNA , Frequência do Gene , Genes/genética , Dados de Sequência Molecular , Desnaturação de Ácido NucleicoRESUMO
Booroola Merino sheep are characterized by a high ovulation rate attributable to the presence of the FecB allele of the FEC gene. This gene, which has been assigned to sheep chromosome 6, is linked to the gene for EGF, which in man is located on the long arm of chromosome 4 (HSA 4q). To increase the number of known markers on sheep chromosome 6, we used comparative mapping data from sheep, man, and cattle. In our study, we show a synteny between EGF and the genes PDHA2 and FGF5 (from HSA 4q) and microsatellites ILSTS018, ILSTS090, and ILSTS093 (from bovine chromosome 6) in sheep. We also show that the conservation between HSA 4q and sheep chromosome 6 is disrupted between EGF and FGF2.
Assuntos
Bovinos/genética , Cromossomos Humanos Par 4/genética , Sequência Conservada/genética , Ovinos/genética , Animais , Sequência de Bases , Humanos , Dados de Sequência Molecular , Reação em Cadeia da PolimeraseRESUMO
The murine Ity/Lsh/Bcg locus belongs to a conserved region between mouse Chromosome 1 and human chromosome 2. This gene governs mouse resistance to several intracellular pathogens. We have localized the gene on sheep chromosome 2q41-->q42 by radioactive in situ hybridization using a 2.1-kb fragment of the ovine equivalent of this gene.
Assuntos
Proteínas de Transporte/genética , Proteínas de Transporte de Cátions , Proteínas de Ligação ao Ferro , Proteínas de Membrana/genética , Ovinos/genética , Animais , Mapeamento Cromossômico/veterinária , Hibridização In Situ/veterinária , Cariotipagem/veterináriaAssuntos
Proteínas de Transporte/genética , Proteínas de Transporte de Cátions , Mapeamento Cromossômico/veterinária , Proteínas de Ligação ao Ferro , Proteínas de Membrana/genética , Ovinos/genética , Sequência de Aminoácidos , Animais , Bovinos , Cricetinae , Células Híbridas , Imunidade Inata/genética , Macrófagos/metabolismo , Camundongos , Dados de Sequência Molecular , Salmonelose Animal/imunologia , Homologia de Sequência de Aminoácidos , Ovinos/imunologiaRESUMO
Animals from the Booroola line of Australian Merino sheep are characterized by a high ovulation rate that can be attributed to the presence of a codominant allele (FecB). The specific function of the gene has not been identified. Effective use of the trait within the sheep breeding industry requires one or more genetic markers that can distinguish between alternative alleles at the locus Fec. With a combination of DNA minisatellite markers and polymorphic protein markers, a cluster of seven minisatellite fragments has been identified as being linked to the Fec gene and to the ovine A blood group locus. The minisatellite fragments have been derived from multilocus probes and hence cannot be used to define the chromosomal location of the Fec gene or to serve as diagnostic markers for Fec. The derivation of cloned single locus markers from the minisatellite fragments will enable finer scale mapping of the Fec and the A blood group locus in sheep.
Assuntos
Fertilidade/genética , Ovulação/genética , Ovinos/genética , Animais , Pré-Escolar , DNA/análise , Feminino , Ligação Genética , Marcadores Genéticos , Humanos , Lactente , Cariotipagem , Escore Lod , MasculinoRESUMO
The M13.13 minisatellite probe, consisting of a polymer of the M13 VNTR consensus sequence, cross-hybridized to ovine DNA and allowed detection of several polymorphic loci. Individual specific patterns were obtained in sheep using this probe. Pedigree analysis showed that individuals were heterozygous for most of the DNA fragments detected (88%). By studying the segregation of male's variable DNA fragments, a minimum of 10 loci were defined. The ovine DNA 'fingerprint' obtained with M13.13 is polymorphic enough to be used efficiently in animal identification, paternity testing, and possibly as a source of genetic markers for linkage analysis.
