An approach on the migratory processes in the north of Chile based on Y chromosome analysis.

OBJECTIVES: Northern Chile is an area characterized by a complex cultural and demographic trajectory. During the last few centuries, this complex trajectory has become the destination of intra- and intercontinental migratory waves. In this study, we analyzed the Y chromosome to evaluate how migratory and admixture patterns have affected the genetic composition of the populations in northern Chile compared with other populations of the country. METHODS: A total of 311 people from urban (Antofagasta and Calama), rural (Azapa and Camarones), and Native (Aymara and Atacameño) populations from northern Chile were characterized by 26 SNPs and the STR DYS393 of the Y chromosome, along with 69 individuals from Native populations (Mapuche, Pehuenche, and Huilliche) from southern Chile. In addition to characterizing the paternal lineages, multivariate analyses were performed to compare with published data from other Chilean populations. RESULTS: Both the Antofagasta and Calama populations show differences compared with the rest of the Chilean population. On one side, Antofagasta shows a high diversity of non-Amerindian lineages, including the highest value for haplogroup I (12%) for all Chileans populations. Otherwise, Calama has the highest value of any Chilean urban population (31.9%) for Amerindian lineages, including the only Q-M3 sub-lineage detected in the entire sample. Regarding the Native population, Aymara presents the highest percentage of Q-M3 (94.4%). CONCLUSIONS: The Y chromosome haplogroup distribution allowed us to identify recent migratory processes typical of the northern populations studied. These have shaped the demographic and cultural dynamics of local and migrant groups in the territory.

Native American mitochondrial lineages in admixed populations from Chile: Detecting recent migrations during post-Columbian times using geographically restricted lineages.

OBJECTIVES: To analyze the mitochondrial diversity in three admixed populations and evaluate the historical migration effect of native southern population movement to Santiago (capital of Chile). The intensity of migration was quantified using three mitochondrial lineages restricted to South-Central native groups. METHODS: D-loop sequences were genotyped in 550 unrelated individuals from San Felipe-Los Andes (n = 108), Santiago (n = 217), and Concepción (n = 225). Sequence processing, alignment, and haplogroup inference were carried out, and different genetic structure analyses were performed for haplogroup frequencies and D-loop sequences. RESULTS: The Native lineages B2i2, C1b13, and D1g were the most frequent haplogroups, especially in Santiago (71.8%). Despite the distance, this city showed a high-genetic affinity with southern populations, including Concepción (~500 km distant) and native groups, rather than with those from San Felipe-Los Andes (<100 km distant). In fact, there was a negative correlation between geographical and genetic distance among these cities (r corr = -0.5593, p value = 0.8387). Network analysis revealed shared haplotypes between Santiago, Concepción, and other southern populations. Finally, we found lineages from Concepción acting as ancestral nodes in the northern clade. CONCLUSIONS: Considering the geographic distances from these cities, the results were not consistent with a model of genetic isolation by geographic distance, revealing the effects of a historical migration process from the south to the capital. We also show evidence of possible north-to-south migration during admixture onset in Concepción and in addition, we were able to identify previously unreported mitochondrial diversity in urban populations that became lost in Native groups post-European contact.

Uniparental origins of the admixed Argentine Patagonia.

OBJECTIVES: We aimed to contribute to the understanding of the ancient geographic origins of the uniparentally inherited markers in modern admixed Argentinian populations from central Patagonia with new information provided for the city of Trelew. We attempted to highlight the importance of combining different genetic markers when studying population history. METHODS: The mtDNA control region sequence was typified in 89 individuals and 12 Y-STR and 15 Y-SNP loci were analyzed in 66 males. With these data, analysis of molecular variance and Network analyses were carried out. We exhaustively compared the modern data with ancient mtDNA information. Finally, we tested the differences in continental origins estimated by uniparental and previously published biparental markers. RESULTS: Native American mtDNAs (53.9%) increased when maternal ancestors were born in the northern (81.8%) and southern (58.5%) regions of Argentina or in Chile (77.8%). Population substructure was only observed for Y-chromosome haplotypes. Some mtDNA haplogroups have been present in the area for at least ca. 2762-2430 and ca. 500 (D1g and D1g4 haplogroups) and ca. 6736 and ca. 6620 (C1b and C1c haplogroups) years, respectively. In contrast, haplogroups B2i2 and C1b13, frequent in modern Patagonia populations, had not been found in previous ancient DNA studies of the region. CONCLUSIONS: The results suggest that Native American ancestry is well preserved in the region. Trelew samples had characteristic native mtDNA haplogroups previously described in Chilean and Argentine Patagonian populations, but not observed in ancient samples until now. These findings support the idea that these lineages have a recent regional origin. Finally, the estimated proportions of continental ancestry depend on the genetic marker analyzed.

Arrival of Paleo-Indians to the southern cone of South America: new clues from mitogenomes.

With analyses of entire mitogenomes, studies of Native American mitochondrial DNA (MTDNA) variation have entered the final phase of phylogenetic refinement: the dissection of the founding haplogroups into clades that arose in America during and after human arrival and spread. Ages and geographic distributions of these clades could provide novel clues on the colonization processes of the different regions of the double continent. As for the Southern Cone of South America, this approach has recently allowed the identification of two local clades (D1g and D1j) whose age estimates agree with the dating of the earliest archaeological sites in South America, indicating that Paleo-Indians might have reached that region from Beringia in less than 2000 years. In this study, we sequenced 46 mitogenomes belonging to two additional clades, termed B2i2 (former B2l) and C1b13, which were recently identified on the basis of mtDNA control-region data and whose geographical distributions appear to be restricted to Chile and Argentina. We confirm that their mutational motifs most likely arose in the Southern Cone region. However, the age estimate for B2i2 and C1b13 (11-13,000 years) appears to be younger than those of other local clades. The difference could reflect the different evolutionary origins of the distinct South American-specific sub-haplogroups, with some being already present, at different times and locations, at the very front of the expansion wave in South America, and others originating later in situ, when the tribalization process had already begun. A delayed origin of a few thousand years in one of the locally derived populations, possibly in the central part of Chile, would have limited the geographical and ethnic diffusion of B2i2 and explain the present-day occurrence that appears to be mainly confined to the Tehuelche and Araucanian-speaking groups.

An alternative model for the early peopling of southern South America revealed by analyses of three mitochondrial DNA haplogroups.

After several years of research, there is now a consensus that America was populated from Asia through Beringia, probably at the end of the Pleistocene. But many details such as the timing, route(s), and origin of the first settlers remain uncertain. In the last decade genetic evidence has taken on a major role in elucidating the peopling of the Americas. To study the early peopling of South America, we sequenced the control region of mitochondrial DNA from 300 individuals belonging to indigenous populations of Chile and Argentina, and also obtained seven complete mitochondrial DNA sequences. We identified two novel mtDNA monophyletic clades, preliminarily designated B2l and C1b13, which together with the recently described D1g sub-haplogroup have locally high frequencies and are basically restricted to populations from the extreme south of South America. The estimated ages of D1g and B2l, about ~15,000 years BP, together with their similar population dynamics and the high haplotype diversity shown by the networks, suggests that they probably appeared soon after the arrival of the first settlers and agrees with the dating of the earliest archaeological sites in South America (Monte Verde, Chile, 14,500 BP). One further sub-haplogroup, D4h3a5, appears to be restricted to Fuegian-Patagonian populations and reinforces our hypothesis of the continuity of the current Patagonian populations with the initial founders. Our results indicate that the extant native populations inhabiting South Chile and Argentina are a group which had a common origin, and suggest a population break between the extreme south of South America and the more northern part of the continent. Thus the early colonization process was not just an expansion from north to south, but also included movements across the Andes.

In vitro antiproliferative activity of 3 H-spiro [1-benzofuran-2,1'-cyclohexane] derivatives / Actividad antiproliferativa in vitro de derivados de 3 H-spiro [1-benzofuran-2, 1'-cyclohexano]

The in vitro effect of the resinous exudate of Heliotropium filifolium, of the 3 H-spiro[1-benzofuran-2,1 '-cyclohexane] derivative called filifolinol 1, isolated from the resin and the semi-synthetic compounds filifolinone 2 and filifolinoic acid 3, obtained from filifolinol 1, were evaluated on the proliferation of an immortalized cell line, UCHT1, derived from rat thyroid. We evaluated the effect of these compounds on UCHT1 cell growth parameters by calculating doubling time; and toxicity using the LIVE/DEAD™ in vitro test. The results showed that the resin is not active, while filifolinone 2, filifolinoic acid 3 and filifolinol 1 produced a significant inhibition of cell doubling time, in concentrations equal or greater than 50, 25 and 75 uM, respectively. The LIVE/DEAD test showed no significant toxicity at these concentrations, compared to cultures kept in absence of compounds. These results suggest a possible cytostatic effect of these compounds, and could therefore constitute potential alternatives for antineoplasic therapy.

Se evaluó el efecto in vitro de la resina aislada desde Heliotropium filifolium y del derivado 3 H-spiro[1-benzofuran-2,1'-cyclohexano] llamado filifolinol 1, obtenido desde este exudado resinoso y los compuestos semi-sintéticos filifolinona 2 y ácido filifolinoico 3, obtenidos a partir de filifolinol 1, sobre la proliferación de la línea celular inmortal, UCHT1, derivada de tumor de tiroide de rata. Evaluamos el efecto de estos compuestos en el desarrollo celular de UCHT1 a través de los parámetros tiempo de doblaje y citotoxicidad usando el test LIVE/DEAD™ in vitro. Los resultados mostraron que la resina no presentó actividad y que filifolinona, ácido filifolinoico y filifolinol producen una inhibición significativa del tiempo de doblaje celular, en concentraciones iguales o superiores a 50, 25 y 75 uM, respectivamente. El test LIVE/DEAD no mostró toxicidad significativa en comparación con los cultivos mantenidos en ausencia de compuestos. Estos resultados sugieren un posible efecto citostático de estos compuestos y por lo tanto, constituirían alternativas potenciales para terapia antineoplásica.

Knockdown of amyloid precursor protein normalizes cholinergic function in a cell line derived from the cerebral cortex of a trisomy 16 mouse: An animal model of down syndrome.

We have generated immortal neuronal cell lines from normal and trisomy 16 (Ts16) mice, a model for Down syndrome (DS). Ts16 lines overexpress DS-related genes (App, amyloid precursor protein; Sod1, Cu/Zn superoxide dismutase) and show altered cholinergic function (reduced choline uptake, ChAT expression and fractional choline release after stimulation). As previous evidence has related amyloid to cholinergic dysfunction, we reduced APP expression using specific mRNA antisense sequences in our neuronal cell line named CTb, derived from Ts16 cerebral cortex, compared to a cell line derived from a normal animal, named CNh. After transfection, Western blot studies showed APP expression knockdown in CTb cells of 36% (24 hr), 40.4% (48 hr), and 50.2% (72 hr) compared to CNh. Under these reduced APP levels, we studied 3H-choline uptake in CTb and CNh cells. CTb, as reported previously, expressed reduced choline uptake compared to CNh cells (75%, 90%, and 69% reduction at 1, 2, and 5 min incubation, respectively). At 72 hr of APP knockdown, choline uptake levels were essentially similar in both cell types. Further, fractional release of 3H-choline in response to glutamate, nicotine, and depolarization with KCl showed a progressive increase after APP knockdown, reaching values similar to those of CNh after 72 hr of transfection. The results suggest that APP overexpression in CTb cells contributes to impaired cholinergic function, and that gene knockdown in CTb cells is a relevant tool to study DS-related dysfunction.