We analyzed the main karyologic changes that have occurred during the dispersion of Triatoma infestans, the main vector of Chagas disease. We identified two allopatric groups, named Andean and non-Andean. The Andean specimens present C-heterochromatic blocks in most of their 22 chromosomes, whereas non-Andean specimens have only 4–7 autosomes with C-banding. These heterochromatin differences are the likely cause of a striking DNA content variation (approximately 30%) between Andean and non-Andean insects. Our study, together with previous historical and genetic data, suggests that T. infestans was originally a sylvatic species, with large quantities of DNA and heterochromatin, inhabiting the Andean region of Bolivia. However, the spread of domestic T. infestans throughout the non-Andean regions only involved insects with an important reduction of heterochromatin and DNA amounts. We propose that heterochromatin and DNA variation mainly reflected adaptive genomic changes that contribute to the ability of T. infestans to survive, reproduce, and disperse in different environments.

BackgroundInsulin-like growth factor 1 (IGF-1) gene is considered as a promising candidate for the identification of polymorphisms affecting cattle performance. The objectives of the current study were to determine the association of the single nucleotide polymorphism (SNP) IGF-1/SnaBI with fertility, milk production and body condition traits in Holstein-Friesian dairy cows under grazing conditions.MethodsSeventy multiparous cows from a commercial herd were genotyped for the SNP IGF-1/SnaBI. Fertility measures evaluated were: interval to commencement of luteal activity (CLA), calving to first service (CFS) and calving to conception (CC) intervals. Milk production and body condition score were also evaluated. The study period extended from 3 wk before calving to the fourth month of lactation.Results and discussionFrequencies of the SNP IGF-1/SnaBI alleles A and B were 0.59 and 0.41, respectively. Genotype frequencies were 0.31, 0.54 and 0.14 for AA, AB and BB, respectively. Cows with the AA genotype presented an early CLA and were more likely to resume ovarian cyclicity in the early postpartum than AB and BB ones. No effect of the SNP IGF-1/SnaBI genotype was evidenced on body condition change over the experimental period, suggesting that energy balance is not responsible for the outcome of postpartum ovarian resumption in this study. Traditional fertility measures were not affected by the SNP IGF-1/SnaBI.ConclusionTo our knowledge this is the first report describing an association of the SNP IGF-1/SnaBI with an endocrine fertility measure like CLA in cattle. Results herein remark the important role of the IGF-1gene in the fertility of dairy cows on early lactation and make the SNP IGF-1/SnaBI an interesting candidate marker for genetic improvement of fertility in dairy cattle.

The chromosome numbers of 46 out of the 122 currently recognized species of Triatominae (Hemiptera, Reduviidae) are summarized. We present the number of autosomes, the sex mechanism and the first reference for each karyotype.

BackgroundService sire has a considerable impact on reproductive success in dairy cattle. Most gene mapping studies for bull fertility have focused on additive effects, while non-additive effects have been largely ignored. The main goal of this study was to assess the relevance of non-additive effects on Sire Conception Rate (SCR) in Holstein dairy cattle. The analysis included 7.5 k Holstein bulls with both SCR records and 57.8 k single nucleotide polymorphism (SNP) markers spanning the entire genome.ResultsThe importance of non-additive effects was evaluated using an efficient two-step mixed model-based approach. Four genomic regions located on chromosomes BTA8, BTA9, BTA13 and BTA17 showed marked dominance and/or recessive effects. Most of these regions harbor genes, such as ADAM28, DNAJA1, TBC1D20, SPO11, PIWIL3 and TMEM119, that are directly implicated in testis development, male germ line maintenance, and sperm maturation.ConclusionsThis study provides further evidence for the relevance of non-additive effects in fitness-related traits, such as male fertility. In addition, these findings may point out new strategies for improving service sire fertility in dairy cattle via marker-assisted selection.