Analisi di sistemi genetici a trasmissine uniparentale = Analysis of uniparentally transmitted genetic systems

The analysis of the variability of the uniparentally transmitted genetic systems, as the mitochondrial DNA (mtDNA) and the non-recombining region of Y chromosome (NRY), is considered a useful tool to study evolutionary processes. In the present PhD Thesis both haploid systems were analyzed in different organisms by a phylogenetic and phylogeographic approaches. In the first part, the variability of mtDNA has been analyzed in domestic Horse. In particular, two Sardinian native breeds -the Giara and Sarcidano horse- were studied in order to determine their genetic structure and phylogenetic history by a comparison in a global framework. The project regarding the creation of a new informatics tool- HapSign Software- to assign mtDNA haplotypes is also reported with the first results of application in horse breeds. The second part encompasses a study focused on the mtDNA variation of a Sardinian endemic genus of Carabidae (Coleoptera) of the subterranean fauna, with the aim to establish the phylogenetic relations among species already known and potentially new ones, coming from some Sardinian caves. Finally, some studies about mtDNA and Y chromosome variation in human populations were conducted; the first one concern the high resolution phylogeny of the NRY of Sardinian population by the sequencing of a large portion of Y chromosome. The other studies has been focused on Italian and African populations in order reconstruct their history from a genetic perspective

The History and geography of the Y chromosome SNPs in Europe: an update

The knowledge of the evolution of the human genome is strictly dependent on the availability of appropriate genetic markers and their relative coverage of genetic variation which refine the phylogenetic reconstruction. While autosomal markers are particularly valuable for recognizing correspondence between genetic and geographic distances, markers on mitochondrial DNA (mtDNA) or Non Recombining Portion of Y Chromosome (NRY), because of their unilinear transmission, can effectively trace diachronical patterns of the human peopling. The maximum extent of polymorphism coverage has already been reached for the very small mitochondrial genome (about 16,5 Kbp), whereas the first studies based on RFLPs (Restriction Fragment Length Polymorphisms) (Cann et al., 1987) and on sequencing of the hypervariable regions (Vigliant et al., 1991), were then combined to get higher resolution (Torroni et al., 1996), and finally the complete genome sequencing is now routinely performed (Achilli et al., 2004, Pala et al., 2009), in order to detect the whole mtDNA variation. A similar approach cannot be used yet at population level for the by far larger nuclear genome. However, advances in genotyping technology have dramatically enhanced the resolution of the analysis at genome-wide level, and recent papers significantly improved the knowledge of the relationships among European populations, using 300 to 500 K SNPs (Single Nucleotide Polymorphisms) on microarrays chips (Tian et al., 2008; Novembre et al., 2008). As to the NRY, most of the studies before the year 2000 were performed using Alu insertion (Hammer, 1995) or STRs (Short Tandem Repeats) (De Knijff et al., 1997; Pritchard et al., 1999) with the known limitations due to recurrence and reversion of this kind of polymorphisms. Using D-HPLC (Denaturing High Performance Liquid Chromatography) technology, Underhill and coworkers (1997) discovered 22 new SNP biallelic markers, rapidly raising in number to 167 (Underhill et al., 2000), 242 (YCC, 2002), about 600 (Karafet et al., 2008), up to more than 725 presently listed in the Y-DNA SNP Index 2009, (www.isogg. org), and the knowledge of Y chromosome phylogeny and of the spread worldwide of human populations raised proportionally. The next goal of the research on Y chromosome will be the use of specific microarrays that can genotype a much higher number of SNPs than nowadays routinely performed, and, ultimately, the complete Y chromosome sequencing. Waiting for future developments, this short note reports the state of the art of the phylogenetic (“history”) and phylogeographic (“geography”) research on Y chromosome SNP analyses in Europe, updating the review published in this Journal by Francalacci & Sanna at the beginning of 2008

Detection of phylogenetically informative polymorphisms in the entire euchromatic portion of human Y chromosome from a Sardinian sample

Background: Next-Generation Sequencing methods have led to a great increase in phylogenetically useful markers within the male specific portion of the Y chromosome, but previous studies have limited themselves to the study of the X-degenerate regions. Methods: DNA was extracted from peripheral blood samples of adult males whose paternal grandfathers were born in Sardinia. The DNA samples were sequenced, genotyped and subsequently analysed for variant calling for approximately 23.1 Mbp of the Y chromosome. A phylogenetic tree was built using Network 4.6 software. Results: From low coverage whole genome sequencing of 1,194 Sardinian males, we extracted 20,155 phylogenetically informative single nucleotide polymorphisms from the whole euchromatic region, including the X-degenerate, X-transposed, and Ampliconic regions, along with variants in other unclassified chromosome intervals and in the readable sequences of the heterochromatic region. Conclusions: The non X-degenerate classes contain a significant portion of the phylogenetic variation of the whole chromosome and their inclusion in the analysis, almost doubling the number of informative polymorphisms, refining the known molecular phylogeny of the human Y chromosome

The Family Name as Socio-Cultural Feature and Genetic Metaphor: From Concepts to Methods

A recent workshop entitled The Family Name as Socio-Cultural Feature and Genetic Metaphor: From Concepts to Methods was held in Paris in December 2010, sponsored by the French National Centre for Scientific Research (CNRS) and by the journal Human Biology. This workshop was intended to foster a debate on questions related to the family names and to compare different multidisciplinary approaches involving geneticists, historians, geographers, sociologists and social anthropologists. This collective paper presents a collection of selected communications

Uniparental markers in Italy reveal a sex-biased genetic structure and different historical strata

University of Adelaide Genographic Consortium contributers: Christina J. Adler, Alan Cooper, Clio S. I. Der Sarkissian, Wolfgang Haak.Located in the center of the Mediterranean landscape and with an extensive coastal line, the territory of what is today Italy has played an important role in the history of human settlements and movements of Southern Europe and the Mediterranean Basin. Populated since Paleolithic times, the complexity of human movements during the Neolithic, the Metal Ages and the most recent history of the two last millennia (involving the overlapping of different cultural and demic strata) has shaped the pattern of the modern Italian genetic structure. With the aim of disentangling this pattern and understanding which processes more importantly shaped the distribution of diversity, we have analyzed the uniparentally-inherited markers in ~900 individuals from an extensive sampling across the Italian peninsula, Sardinia and Sicily. Spatial PCAs and DAPCs revealed a sex-biased pattern indicating different demographic histories for males and females. Besides the genetic outlier position of Sardinians, a North West–South East Y-chromosome structure is found in continental Italy. Such structure is in agreement with recent archeological syntheses indicating two independent and parallel processes of Neolithisation. In addition, date estimates pinpoint the importance of the cultural and demographic events during the late Neolithic and Metal Ages. On the other hand, mitochondrial diversity is distributed more homogeneously in agreement with older population events that might be related to the presence of an Italian Refugium during the last glacial period in Europe.Alessio Boattini, Begoña Martinez-Cruz, Stefania Sarno, Christine Harmant, Antonella Useli, Paula Sanz, Daniele Yang-Yao, Jeremy Manry, Graziella Ciani, Donata Luiselli, Lluis Quintana- Murci, David Comas, Davide Pettener, the Genographic Consortiu

Human microevolution and the atlantic slave trade: A case study from Säo Tomé

Populations derived from the Atlantic slaving process provide unique opportunities for studying key evolutionary determinants of current patterns of human cultural and biological variation. Examination of the genetic patterning of the small plantation island of São Tomé (Gulf of Guinea) using a study design that avoids the use of preconceived ethno-linguistic labels to define genetic sampling units reveals that, despite the fact that maximum distance between any two sampled sites is less than 50 km, the island has an unusual level of genetic structure that is mainly caused by the grouping of Angolar Creole-speakers in a separate cluster carrying a distinctive imprint of genetic drift. This pattern may have been shaped by a kin-structured founder effect associated with the flight of a patrilineal clan of rebel slaves who established a remarkably successful maroon community in the vicinity of the plantation complex. The observation that population-discontinuous jumps may occur even under social conditions of massive coercive amalgamation provides an illustration of the way in which human clusters emerge and eventually shape the genetic background of human populations. © 2008 by The Wenner-Gren Foundation for Anthropological Research. All rights reserved

Uniparental markers in Italy reveal a sex-biased genetic structure and different historical strata

Located in the center of the Mediterranean landscape and with an extensive coastal line, the territory of what is today Italy has played an important role in the history of human settlements and movements of Southern Europe and the Mediterranean Basin. Populated since Paleolithic times, the complexity of human movements during the Neolithic, the Metal Ages and the most recent history of the two last millennia (involving the overlapping of different cultural and demic strata) has shaped the pattern of the modern Italian genetic structure. With the aim of disentangling this pattern and understanding which processes more importantly shaped the distribution of diversity, we have analyzed the uniparentally-inherited markers in 900 individuals from an extensive sampling across the Italian peninsula, Sardinia and Sicily. Spatial PCAs and DAPCs revealed a sex-biased pattern indicating different demographic histories for males and females. Besides the genetic outlier position of Sardinians, a North West–South East Y-chromosome structure is found in continental Italy. Such structure is in agreement with recent archeological syntheses indicating two independent and parallel processes of Neolithisation. In addition, date estimates pinpoint the importance of the cultural and demographic events during the late Neolithic and Metal Ages. On the other hand, mitochondrial diversity is distributed more homogeneously in agreement with older population events that might be related to the presence of an Italian Refugium during the last glacial period in EuropeThis study was supported by Strategic Project 2006-09 from the University of Bologna to DP and from MIUR PRIN 2007 and 2009 Grants to DP. The project was also supported by the Spanish Government grant CGL2010-14944/BO

Peopling of three Mediterranean Islands (Corsica, Sardinia, and Sicily) inferred by Y-chromosome biallelic variability

chromosome variability in a sample from the Mediterranean islands of Corsica and Sicily, and compared with data on Sardinia to gain insights into the ethnogenesis of these island populations. The results were interpreted in a broader Mediterranean context by including in the analysis neighboring populations previously studied with the same methodology. All samples studied were enclosed in the comparable spectrum of European Y-chromosome variability. Pronounced differences were observed between the islands as well as in the percentages of haplotypes previously shown to have distinctive patterns of continental phylogeography. Approximately 60% of the Sicilian haplotypes are also prevalent in Southern Italy and Greece. Conversely, the Corsican sample had elevated levels of alternative haplotypes common in Northern Italy. Sardinia showed a haplotype ratio similar to that observed in Corsica, but with a remarkable difference in the presence of a lineage defined by marker M26, which approaches 35% in Sardinia but seems absent in Corsica. Although geographically adjacent, the data suggest different colonization histories and a minimal amount of recent gene flow between them. Our results identify possible ancestral continental sources of the various island populations and underscore the influence of founder effect and genetic drift. The Y-chromosome data are consistent with comparable mtDNA data at the RFLP haplogroup level of resolution, as well as linguistic and historic knowledge