Gas phase Elemental abundances in Molecular cloudS (GEMS) I : The prototypical dark cloud TMC 1

GEMS is an IRAM 30 m Large Program whose aim is determining the elemental depletions and the ionization fraction in a set of prototypical star-forming regions. This paper presents the first results from the prototypical dark cloud Taurus molecular cloud (TMC) 1. Extensive millimeter observations have been carried out with the IRAM 30 m telescope (3 and 2mm) and the 40 m Yebes telescope (1.3 cm and 7 mm) to determine the fractional abundances of CO, HCO+, HCN, CS, SO, HCS+, and N2H+ in three cuts which intersect the dense filament at the well-known positions TMC 1-CP, TMC 1-NH3, and TMC 1-C, covering a visual extinction range from A(v) similar to 3 to similar to 20 mag. Two phases with differentiated chemistry can be distinguished: (i) the translucent envelope with molecular hydrogen densities of 1-5 x 10(3) cm(-3); and (ii) the dense phase, located at A(v) > 10 mag, with molecular hydrogen densities >10(4) cm(-3). Observations and modeling show that the gas phase abundances of C and O progressively decrease along the C+/C/CO transition zone (A(v) similar to 3 mag) where C/H similar to 8 x 10(-5) and C/O similar to 0.8-1, until the beginning of the dense phase at A(v) similar to 10 mag. This is consistent with the grain temperatures being below the CO evaporation temperature in this region. In the case of sulfur, a strong depletion should occur before the translucent phase where we estimate an S/H similar to (0.4-2.2) x 10(-6), an abundance similar to 7-40 times lower than the solar value. A second strong depletion must be present during the formation of the thick icy mantles to achieve the values of S/H measured in the dense cold cores (S/H similar to 8 x 10(-8)). Based on our chemical modeling, we constrain the value of zeta(H2) to similar to(0.5-1.8) x 10(-16) s(-1) in the translucent cloud.Peer reviewe

Analyses of DNA from ancient bones of a pre-Columbian Cuban woman and a child

Molecular anthropology has brought new possibilities into the study of ancient human populations. Amplification of chromosomal short tandem repeat (STR) loci and mitochondrial DNA (mtDNA) has been successfully employed in analyses of ancient bone material. Although several studies have reported on continental Amerindian populations, none have addressed the ancient populations inhabiting the Caribbean islands. We used STR and mtDNA analyses to study the skeletal remains of a Cuban Ciboney female adult holding an infant. Results showed that for the STR analyzed the skeletal remains shared common alleles, suggesting a relationship. Mitochondrial DNA analysis showed sequence identity, thus corroborating a possible mother-child relationship. The mtDNA sequence grouped these remains into haplogroup A, commonly found in Amerindian populations. Based on these results, we speculated on a South American origin of pre-Columbian Antilles populations and possible infanticide practices in these populations. This constitutes the first report on DNA analysis of ancient pre-Columbian Cuban populations.<br>A antropologia molecular trouxe novas possibilidades para o estudo de populações humanas antigas. A amplificação de loci em pequenos segmentos cromossômicos repetidos (short tandem repeat, STR) e de DNA mitocondrial (mtDNA) tem sido empregada com sucesso em análises de material ósseo antigo. Embora vários estudos tenham sido publicados a respeito de populações ameríndias continentais, nenhum estudou as populações antigas que habitavam as ilhas do Caribe. Nós usamos análise de STR e mtDNA para estudar os restos de ossos de uma mulher adulta da tribo Ciboney cubana carregando uma criança. Os resultados mostraram que para o STR analisado os restos ósseos compartilhavam alelos comuns, sugerindo um parentesco. A análise de mtDNA mostrou identidade de seqüência, corroborando assim uma possível relação mãe-filho. A seqüência de mtDNA alocou esses restos no haplogrupo A, comumente encontrado em populações ameríndias. Baseado nesses resultados, nós especulamos a respeito de uma origem sul-americana para as populações pré-colombianas das Antilhas e possíveis práticas infanticidas nessas populações. Este constitui o primeiro relato de análise de DNA em populações cubanas pré-colombianas antigas