A common copy-number variant within SIRPB1 correlates with human Out-of-Africa migration after genetic drift correction.

Previous reports have proposed that personality may have played a role on human Out-Of-Africa migration, pinpointing some genetic variants that were positively selected in the migrating populations. In this work, we discuss the role of a common copy-number variant within the SIRPB1 gene, recently associated with impulsive behavior, in the human Out-Of-Africa migration. With the analysis of the variant distribution across forty-two different populations, we found that the SIRPB1 haplotype containing duplicated allele significantly correlated with human migratory distance, being one of the few examples of positively selected loci found across the human world colonization. Circular Chromosome Conformation Capture (4C-seq) experiments from the SIRPB1 promoter revealed important 3D modifications in the locus depending on the presence or absence of the duplication variant. In addition, a 3' enhancer showed neural activity in transgenic models, suggesting that the presence of the CNV may compromise the expression of SIRPB1 in the central nervous system, paving the way to construct a molecular explanation of the SIRPB1 variants role in human migration.

Differential metabolic profiles associated to movement behaviour of stream-resident brown trout (Salmo trutta).

The mechanisms that can contribute in the fish movement strategies and the associated behaviour can be complex and related to the physiology, genetic and ecology of each species. In the case of the brown trout (Salmo trutta), in recent research works, individual differences in mobility have been observed in a population living in a high mountain river reach (Pyrenees, NE Spain). The population is mostly sedentary but a small percentage of individuals exhibit a mobile behavior, mainly upstream movements. Metabolomics can reflect changes in the physiological process and can determine different profiles depending on behaviour. Here, a non-targeted metabolomics approach was used to find possible changes in the blood metabolomic profile of S. trutta related to its movement behaviour, using a minimally invasive sampling. Results showed a differentiation in the metabolomic profiles of the trouts and different level concentrations of some metabolites (e.g. cortisol) according to the home range classification (pattern of movements: sedentary or mobile). The change in metabolomic profiles can generally occur during the upstream movement and probably reflects the changes in metabolite profile from the non-mobile season to mobile season. This study reveals the contribution of the metabolomic analyses to better understand the behaviour of organisms.

Genotyping of common SIRPB1 copy number variant using Paralogue Ratio Test coupled to MALDI-MS quantification.

Copy number variant (CNV) regions have been proven to have a significant impact on gene expression. Some of them have been also found to be associated to different human diseases. CNV genotyping is often prone to error and cross-validation with independent methods is frequently required. The platform of choice depends on whether it is a genome-wide discovery screening or a candidate CNV study, the cohort size and the number of CNVs included in the assay and, finally, the budget available. Here we illustrate a affordable approach to determine the CNV genotype using matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) and based on the quantitative determination of single nucleotide duplicated mismatches (SNDM) mapping the CNV region and a paralogue genomic region that is used as a two-copy reference. We have genotyped nsv436327, a common CNV mapping SIRPB1 intron 1 that has been associated to human personality behavior. SIRP cluster region was subjected to several ancestral duplication events what makes SIRPB1 CNV genotyping technically challenging. We designed three sets of primer pairs that amplified paralogue regions inside and outside the CNV, containing three SNDMs. Post-PCR extension analyses of sequencing oligonucleotides mapping immediately upstream each SNDM allowed us to quantify using MALDI-MS the proportion of PCR products derived from the CNV region versus the external reference. In contrast to other approaches, setting up this genotyping method requires an affordable investment.