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Our objective was to estimate Bos primigenius taurus introgression in American Zebu cattle. One hundred and four American Zebu (Nellore) cattle were submitted to mtDNA, microsatellite and satellite analysis. Twenty-three alleles were detected in microsatellite analysis, averaging 4.6 ± 1.82/locus. Variance component comparisons of microsatellite allele sizes allowed the construction of two clusters separating taurus and indicus. No significant variation was observed when indicus and taurus mtDNA were compared. Three possible genotypes of 1711b satellite DNA were identified. All European animals showed the same restriction pattern, suggesting a Zebu-specific restriction pattern. The frequencies of B. primigenius indicus-specific microsatellite alleles and 1711b satellite DNA restriction patterns lead to an estimate of 14% taurine contribution in purebred Nellore.

Insulin-like growth factor 1 (IGF1) regulates growth and metabolic functions in vertebrates. A dinucleotide repeat sequence located at the promoter region of the IGF1 gene has been reported in several vertebrate species and may affect the control of the transcriptional activity of this gene. The genotypes of animals from seven horse breeds were determined in order to study the potential association of allelic forms of this microsatellite with adult body size differences found in domestic horses. Among these breeds, five alleles were found. Breed-specific differences in adult body size could not be attributed to the presence or absence of any of the alleles observed. In addition, animals representing five other equid species were typed. Examples of apparent species-specific alleles were found. However, overlapping polymorphic size ranges preclude this microsatellite from being an absolute identifier for species or hybrid status in equids. The polymorphisms found at this IGF1 locus are useful for synteny and linkage mapping.

Characterizes horse dinucleotide repeat loci COR021-COR040. Polymerase chain reaction conditions; Chromosomal location; Allele frequencies; Primer sequences.

Characterizes horse microsatellite loci COR001-COR020. Primer sequences; Polymerase chain reaction conditions; Heterozygosity and polymorphism information content values; Chromosomal location; Allele frequencies.