Rita Gonçalves

Phylogeography of Y-Chromosome Haplogroup I Reveals Distinct Domains of Prehistoric Gene Flow in Europe

To investigate which aspects of contemporary human Y-chromosome variation in Europe are characteristic of primary colonization, late-glacial expansions from refuge areas, Neolithic dispersals, or more recent events of gene flow, we have analyzed, in detail, haplogroup I (Hg I), the only major clade of the Y phylogeny that is widespread over Europe but virtually absent elsewhere. The analysis of 1,104 Hg I Y chromosomes, which were identified in the survey of 7,574 males from 60 population samples, revealed several subclades with distinct geographic distributions. Subclade I1a accounts for most of Hg I in Scandinavia, with a rapidly decreasing frequency toward both the East European Plain and the Atlantic fringe, but microsatellite diversity reveals that France could be the source region of the early spread of both I1a and the less common I1c. Also, I1b*, which extends from the eastern Adriatic to eastern Europe and declines noticeably toward the southern Balkans and abruptly toward the periphery of northern Italy, probably diffused after the Last Glacial Maximum from a homeland in eastern Europe or the Balkans. In contrast, I1b2 most likely arose in southern France/Iberia. Similarly to the other subclades, it underwent a postglacial expansion and marked the human colonization of Sardinia approximately 9,000 years ago.

Y-chromosome Lineages from Portugal, Madeira and Açores Record Elements of Sephardim and Berber Ancestry

A total of 553 Y‐chromosomes were analyzed from mainland Portugal and the North Atlantic Archipelagos of Açores and Madeira, in order to characterize the genetic composition of their male gene pool. A large majority (78–83% of each population) of the male lineages could be classified as belonging to three basic Y chromosomal haplogroups, R1b, J, and E3b. While R1b, accounting for more than half of the lineages in any of the Portuguese sub‐populations, is a characteristic marker of many different West European populations, haplogroups J and E3b consist of lineages that are typical of the circum‐Mediterranean region or even East Africa. The highly diverse haplogroup E3b in Portuguese likely combines sub‐clades of distinct origins. The present composition of the Y chromosomes in Portugal in this haplogroup likely reflects a pre‐Arab component shared with North African populations or testifies, at least in part, to the influence of Sephardic Jews. In contrast to the marginally low sub‐Saharan African Y chromosome component in Portuguese, such lineages have been detected at a moderately high frequency in our previous survey of mtDNA from the same samples, indicating the presence of sex‐related gene flow, most likely mediated by the Atlantic slave trade.

Genetic profile of a multi-ethnic population from Guiné-Bissau (west African coast) using the new PowerPlex 16 System kit.

Allele and haplotype frequencies of 15 chromosome STR loci included in the kit PowerPlex16 System from Promega, were determined in a sample of unrelated males from Guiné-Bissau, a country from the west African coast. All individuals were subjected to an interview in order to make sure that their ancestors belonged to the same ethnic group. This way we intended to look for possible inter-ethnic differences. PowerPlex 16 includes STRs not studied before in any multi-ethnic population. The kit includes two new allele markers (Penta D and Penta E), which are very useful either in forensics or population genetic studies. The Guinean population presents significant differences when compared with other African populations.

Y-chromosome lineages in Cabo Verde Islands witness the diverse geographic origin of its first male settlers

The Y-chromosome haplogroup composition of the population of the Cabo Verde Archipelago was profiled by using 32 single-nucleotide polymorphism markers and compared with potential source populations from Iberia, west Africa, and the Middle East. According to the traditional view, the major proportion of the founding population of Cabo Verde was of west African ancestry with the addition of a minor fraction of male colonizers from Europe. Unexpectedly, more than half of the paternal lineages (53.5%) of Cabo Verdeans clustered in haplogroups I, J, K, and R1, which are characteristic of populations of Europe and the Middle East, while being absent in the probable west African source population of Guiné-Bissau. Moreover, a high frequency of J* lineages in Cabo Verdeans relates them more closely to populations of the Middle East and probably provides the first genetic evidence of the legacy of the Jews. In addition, the considerable proportion (20.5%) of E3b(xM81) lineages indicates a possible gene flow from the Middle East or northeast Africa, which, at least partly, could be ascribed to the Sephardic Jews. In contrast to the predominance of west African mitochondrial DNA haplotypes in their maternal gene pool, the major west African Y-chromosome lineage E3a was observed only at a frequency of 15.9%. Overall, these results indicate that gene flow from multiple sources and various sex-specific patterns have been important in the formation of the genomic diversity in the Cabo Verde islands.

Identification of new breakpoints in AZFb and AZFc

Microdeletions in AZFa, AZFb and AZFc regions lead to different patterns of male infertility, from severe oligozoospermia to non-obstructive azoospermia. Intrachromosomal homologous recombination mechanisms were already identified in patients with simultaneous microdeletions in the AZFb and AZFc regions. Ten patients with atypical AZFb and AZFc deletion patterns were studied. The definition of those microdeletions and the fine characterization of the respective breakpoints were performed using sequence tagged sites/single nucleotide variants-PCR and DNA sequencing. Y-chromosome haplogroups were determined to establish a putative association with the patterns obtained. Seven deletion patterns were identified, P5/terminal (30%; 3/10), P5/P1 distal (20%; 2/10), IR4/distal-P2, IR2/proximal-P1, IR4/distal-P1, P4/terminal and complete AZFb/c deletion (10%; 1/10). Breakpoint sequence analysis suggests that only in one patient the P5/P1 distal deletion pattern was due to a homologous recombination mechanism. Sequence alignment of the other deletion patterns suggest that they have resulted from non-homologous recombination mechanisms.

Forensic analysis of dog (Canis lupus familiaris) mitochondrial DNA sequences: an inter-laboratory study of the GEP-ISFG working group.

A voluntary collaborative exercise aiming at the mitochondrial analysis of canine biological samples was carried out in 2006-2008 by the Non-Human Forensic Genetics Commission of the Spanish and Portuguese Working Group (GEP) of the International Society for Forensic Genetics (ISFG). The participating laboratories were asked to sequence two dog samples (one bloodstain and one hair sample) for the mitochondrial D-loop region comprised between positions 15,372 and 16,083 using suggested primers and PCR conditions, and to compare their results against a reference sequence. Twenty-one participating laboratories reported a total of 67.5% concordant results, 15% non-concordant results, and 17.5% no results. The hair sample analysis presented more difficulty to the participants than the bloodstain analysis, with a high percentage (29%) failing to obtain a result. The high level of participation showed the interest of the community in the analysis of dog forensic samples but the results reveal that crucial methodological issues need to be addressed and further training is required in order to respond proficiently to the demands of forensic casework.

Structure and genetic variation of the mitochondrial control region in the honey bee Apis mellifera

Although the mitochondrial molecule of the honey bee is completely sequenced, the control region is rarely used for genetic inferences as in other invertebrates, due to several constraints mainly a biased A plus T content and extensive variable length repeats. Herein, we have analyzed the control region of honey bees from the Iberian Peninsula and North Atlantic islands. The information retrieved when comparing individuals from different populations was crucial to understand and characterize how the control region is organized in this species. As expected, this region in Apis mellifera appears to contain valuable although limited genetic information at the population level. Furthermore, the comparisons of the A. mellifera control region with other species of the same genus highlight the structural role of particular sequences within the A+T rich control region as proposed here.

Cabo Verde islands: different maternal and paternal heritage testifies the nature of its first settlers

Abstract The Cabo Verde Archipelago was colonized by the Portuguese in the 15th century. The first male settlers were mostly European males who never exceeded 1% of the total population mainly constituted by slaves brought from the West African coast. No European women were among the settlers who went to Cabo Verde without their families and formed liaisons with slaves creating a new class of individuals, the “mullato”. Here, we compare the maternal and paternal heritage of present-day Cabo Verdeans, by looking to their mtDNA and Y-biallelic markers profile. There is a strong asymmetry concerning both markers. The sub-Saharan component account for 93% of the total mitochondrial lineages of Cabo Verdeans, but less than 21% of the Y-chromosomes. The high percentage of Y-chromosome markers with an European affiliation attests for the importance that few lineages existing at the beginning of the settlement became widespread in the population in just 500 years.