Genetic diversity in Svaneti and its implications for the human settlement of the Highland Caucasus.

OBJECTIVES: In this study, we characterized genetic diversity in the Svans from northwestern Georgia to better understand the phylogeography of their genetic lineages, determine whether genetic diversity in the highland South Caucasus has been shaped by language or geography, and assess whether Svan genetic diversity was structured by regional residence patterns. MATERIALS AND METHODS: We analyzed mtDNA and Y-chromosome variation in 184 individuals from 13 village districts and townlets located throughout the region. For all individuals, we analyzed mtDNA diversity through control region sequencing, and, for males, we analyzed Y-chromosome diversity through SNP and STR genotyping. The resulting data were compared with those for populations from the Caucasus and Middle East. RESULTS: We observed significant mtDNA heterogeneity in Svans, with haplogroups U1-U7, H, K, and W6 being common there. By contrast, ∼78% of Svan males belonged to haplogroup G2a, with the remainder falling into four other haplogroups (J2a1, I2, N, and R1a). While showing a distinct genetic profile, Svans also clustered with Caucasus populations speaking languages from different families, suggesting a deep common ancestry for all of them. The mtDNA data were not structured by geography or linguistic affiliation, whereas the NRY data were influenced only by geography. DISCUSSION: These patterns of genetic variation confirm a complex set of geographic sources and settlement phases for the Caucasus highlands. Such patterns may also reflect social and cultural practices in the region. The high frequency and antiquity of Y-chromosome haplogroup G2a in this region further points to its emergence there.

Quantification of heat shock protein 70 and acetylcholinesterase over a time course suggests environmental adaptation in a foundational molluscan species.

Waterways in urban areas often act as repositories for sewage, industrial waste, and environmental contaminants. In response, inhabitants of these watersheds undergo physiological adaptations specific to their respective environments. Effects of these stressors can be assayed by quantification of various well-documented biomarkers in sentinel species such as the Atlantic Ribbed mussel, Geukensia demissa, a native to the Bronx River Estuary, Bronx, NY, USA. Heat shock protein 70 (Hsp70) is a universally expressed biomarker for an array of environmental stressors including toxins and low dissolved oxygen. To better understand the mechanisms by which organisms tolerate their contaminated environments, we monitored the constitutive and heat shock-induced levels of two proteins: Hsp70 and acetylcholinesterase (AChE) in natural populations of G. demissa from differentially impacted sites: the Bronx River and Greenwich Cove estuaries. We show that G. demissa from the Bronx River exhibits a higher level of constitutive Hsp70, and launches a more rapid and robust heat shock response than does its Greenwich Cove counterpart. In addition, AChE levels are recovered more quickly in Bronx River mussels. Based on response pattern investigations from heat stress as well as constitutive expression, we suggest that the Hsp70/AChE chaperone/client relationship exemplifies the unique adaptive mechanisms utilized by organisms in order to tolerate environmentally impacted habitats. Results from this study offer important insights from an ecological perspective into the molecular and cellular basis of stress response and provide valuable information regarding adaptation to the increased demands of challenging environments.