RESUMO
The growth hormone gene (GH1) and its polypeptide product (GH) have a crucial role in reproduction, embryogenesis and general development. A polymorphism present in the fifth exon of the bovine GH1 gene (GH1 p.Leu127Val) has been associated with GH release and milk production in cattle. The objective of the present study was to examine the genotype frequencies of the GH1 p.Leu127Val polymorphism in bovine blastocysts produced in vitro and in vivo to determine if allelic variation of the GH1 gene affects embryo development and survival. A heterozygous (p.Leu127/Val127) sire was used for in vitro fertilization of oocytes of unknown maternal genotype (n = 104) and known maternal genotype (n = 115). PCR amplification and genotyping of the GH1 gene from Day 8 blastocysts derived from these fertilized oocytes demonstrated that there was significant over-representation from the expected Mendelian ratio of GH1 p.Leu127/Leu127 homozygotes from oocytes of known maternal genotype (P = 0.006). Contrary to this, analysis of in vivo-produced bovine blastocysts of known parental GH1 genotype (n = 69) did not reveal an overrepresentation of GH1 p.Leu127/Leu127 homozygotes. These results suggest that developing in vitro-produced embryos are exposed to a selection process, probably due to a less favorable culture environment, that acts to increase the number of GH1 p.Leu127/Leu127 homozygotes, thereby giving rise to the observed transmission ratio distortion (TRD) of GH1 genotypes when compared to in vivo produced embryos.
Assuntos
Blastocisto/fisiologia , Desenvolvimento Embrionário/genética , Éxons/fisiologia , Hormônio do Crescimento/genética , Polimorfismo Genético , Substituição de Aminoácidos , Animais , Bovinos , Técnicas de Cultura Embrionária , Feminino , Hormônio do Crescimento/biossíntese , Homozigoto , Lactação/genética , GravidezRESUMO
Historic DNA data have the potential to identify phenotypic information otherwise invisible in the historical, archaeological and palaeontological record. In order to determine whether a single nucleotide polymorphism typing protocol based on single based extension (SNaPshot™) could produce reliable phenotypic data from historic samples, we genotyped three coat colour markers for a sample of historic Thoroughbred horses for which both phenotypic and correct genotypic information were known from pedigree information in the General Stud Book. Experimental results were consistent with the pedigrees in all cases. Thus we demonstrate that historic DNA techniques can produce reliable phenotypic information from museum specimens.
Assuntos
DNA/genética , Cavalos/genética , Análise de Sequência de DNA/métodos , Alelos , Animais , Primers do DNA/genética , Genótipo , Paleontologia/métodos , Linhagem , Fenótipo , Reação em Cadeia da Polimerase/métodos , Polimorfismo de Nucleotídeo ÚnicoRESUMO
Arthrogryposis is a congenital malformation affecting the limbs of newborn animals and infants. Previous work has demonstrated that inherited ovine arthrogryposis (IOA) has an autosomal recessive mode of inheritance. Two affected homozygous recessive (art/art) Suffolk rams were used as founders for a backcross pedigree of half-sib families segregating the IOA trait. A genome scan was performed using 187 microsatellite genetic markers and all backcross animals were phenotyped at birth for the presence and severity of arthrogryposis. Pairwise LOD scores of 1.86, 1.35, and 1.32 were detected for three microsatellites, BM741, JAZ, and RM006, that are located on sheep Chr 5 (OAR5). Additional markers in the region were identified from the genetic linkage map of BTA7 and by in silico analyses of the draft bovine genome sequence, three of which were informative. Interval mapping of all autosomes produced an F value of 21.97 (p < 0.01) for a causative locus in the region of OAR5 previously flagged by pairwise linkage analysis. Inspection of the orthologous region of HSA5 highlighted a previously fine-mapped locus for human arthrogryposis multiplex congenita neurogenic type (AMCN). A survey of the HSA5 genome sequence identified plausible candidate genes for both IOA and human AMCN.
Assuntos
Artrogripose/veterinária , Doenças dos Ovinos/genética , Ovinos/genética , Animais , Animais Recém-Nascidos , Artrogripose/genética , Sequência de Bases , Bovinos , Mapeamento Cromossômico , Cruzamentos Genéticos , Primers do DNA/genética , Feminino , Genes Recessivos , Humanos , Recém-Nascido , Masculino , Repetições de Microssatélites , LinhagemRESUMO
Both eyes of 74 healthy 2-12-month-old human infants were refracted twice with the new Welch Allyn SureSight non-cycloplegic autorefractor. At least one reliable estimate of sphere and cylinder was obtained from both eyes of all babies attempted, and 88% of infants contributed two estimates from each eye. These measurements were collected in less than 2 min. Although spherical estimates changed little over the first year (mean = +1.78 D), cylindrical error appeared to decrease from a mean of about 1.4 D (at 6 months) to 0.9 D (at 12 months). Refractive estimates and variability agreed well with published infant data obtained with traditional cycloplegic retinoscopy. Repeatability was excellent for measurement of cylinder but for sphere, 17% of infants' estimates differed by at least 1.0 D between tests. However, given its simplicity and time-efficiency, the SureSight should be a good candidate for the relatively easy screening of significant refractive error in non-verbal paediatric patients.