No abstract

Sinipta dalmani is an Argentine grasshopper whose chromosome polymorphisms have been widely studied through cytogenetic, morphometric, and fitness component analyses. The present work analysed molecular and morphometric variation in seven chromosomally differentiated populations from Entre Rios and Buenos Aires provinces to analyse population structure. Molecular studies were performed studying RAPD loci and morphometric analyses were carried out measuring five morphometric traits. Genetic variability was high in all studied populations and was characterized by a decrease in H as a function of latitude and temperature. Both conventional F(ST) analysis and Bayesian approach for dominant marker showed that there were significant genetic differences among all populations, between provinces, and among populations within provinces. Entre Rios populations showed higher mean numbers of migrants per generation as well as low genetic differentiation and high gene flow with almost all populations whereas Buenos Aires populations may be considered as a result of a more recently colonization. There is considerable morphometric variation between populations and this variation correlates with latitude and temperature. Our results suggest that selection contributes to phenotypic differentiation among populations by moulding the differences in trait means whereas genetic drift is responsible for differences in the matrix of variance-covariance. The gene flow detected is insufficient to prevent phenotypic and chromosome divergences.

Autism spectrum disorders (ASD) can be conceptualized as a genetic dysfunction that disrupts development and function of brain circuits mediating social cognition and language. At least some forms of ASD may be associated with high level of excitation in neural circuits, and gamma-aminobutyric acid (GABA) has been implicated in its etiology. Single-nucleotide polymorphisms (SNP) located within the GABA receptor (GABAR) subunit genes GABRA1, GABRG2, GABRB3, and GABRD were screened. A hundred and thirty-six Argentinean ASD patients and 150 controls were studied, and the contribution of the SNPs in the etiology of ASD was evaluated independently and/or through gene-gene interaction using multifactor dimensionality reduction (MDR) method. From the 18 SNP studied, 11 were not present in our Argentinean population (patients and controls) and 1 SNP had minor allele frequency < 0.1%. For the remaining six SNPs, none provided statistical significant association with ASD when considering allelic or genotypic frequencies. Non-significant association with ASD was found for the haplotype analysis. MDR identified evidence for synergy between markers in GABRB3 (chromosome 15) and GABRD (chromosome 1), suggesting potential gene-gene interaction across chromosomes associated with increased risk for autism (testing balanced accuracy: 0.6081 and cross-validation consistency: 10/10, P < 0.001). Considering our Argentinean ASD sample, it can be inferred that GABRB3 would be involved in the etiology of autism through interaction with GABRD. These results support the hypothesis that GABAR subunit genes are involved in autism, most likely via complex gene-gene interactions.