RESUMO
Genetic investigations on ancient human remains affected by rheumatological pathologies are a research field of particular interest for identifying the pathogenesis of diseases, especially those having an autoimmune background such as spondyloarthopaties (SpA). Reliable studies concerning this topic require collaboration between multiple disciplines, usually starting from paleopathologic observations up to molecular genetic screening. Here, we focused our investigation in a medieval necropolis in the Basque Country (13th-15th century, Nâ¯=â¯163), which presents a high frequency of joint pathologies through two approaches: on the one hand, the analysis of joint manifestations for the differential diagnosis of the SpA and, on the other hand, the determination of the alleles of the HLA-B gene. The morphological analysis allowed determining that 30% of the individuals had rheumatic bone manifestations, with SpA being the most frequent (45%). The genetic analysis of individuals with and without pathologies, based on the study of the HLA-B gene, allowed finding 17 alleles for this gene, with HLA-B40, HLA-B27 and HLA-B35 being the most frequent. Although these alleles have been traditionally described as genetic markers associated to the development of SpA, in this study they were also found in individuals with other rheumatic diseases (osteoarthritis and rheumatoid arthritis) and even in individuals without pathologies. These data confirm the complexity of the relationship of the HLA-B gene variants with SpA, since it is not possible to establish a diagnosis of SpA with these variants alone. However, we suggest that allele HLA-B40, in combination with some specific rheumatic bone manifestations, facilitates the diagnosis of SpA.
Assuntos
Artrite Reumatoide/diagnóstico , Antígeno HLA-B27/genética , Antígeno HLA-B35/genética , Antígeno HLA-B40/genética , Osteoartrite/diagnóstico , Polimorfismo Genético , Espondiloartropatias/diagnóstico , Alelos , Artrite Reumatoide/genética , Artrite Reumatoide/imunologia , Artrite Reumatoide/patologia , Restos Mortais , Osso e Ossos/imunologia , Osso e Ossos/patologia , Clima , Temperatura Baixa , DNA Antigo/análise , Diagnóstico Diferencial , Feminino , Predisposição Genética para Doença , Antígeno HLA-B27/imunologia , Antígeno HLA-B35/imunologia , Antígeno HLA-B40/imunologia , História Medieval , Humanos , Articulações/imunologia , Articulações/patologia , Masculino , Osteoartrite/genética , Osteoartrite/imunologia , Osteoartrite/patologia , Paleopatologia/métodos , Espanha , Espondiloartropatias/genética , Espondiloartropatias/imunologia , Espondiloartropatias/patologiaRESUMO
In 1964, a human humerus was found in a sedimentary deposit in Lezetxiki Cave (Basque Country, northern Iberia). The first studies on the stratigraphy, associated mammal faunal remains and lithic implements placed the deposits containing the humerus into the Riss glacial stage. Direct chronometric evidence has so far been missing, and the previous chronostratigraphic framework and faunal dating gave inconsistent results. Here we report laser ablation U-series analyses on the humerus yielding a minimum age of 164 ± 9 ka, corresponding to MIS 6. This is the only direct dating analysis of the Lezetxiki humerus and confirms a Middle Pleistocene age for this hominin fossil. Morphometric analyses suggest that the Lezetxiki humerus has close affinities to other Middle Pleistocene archaic hominins, such as those from La Sima de los Huesos at Atapuerca. This emphasizes the significance of the Lezetxiki fossil within the populations that predate the Neanderthals in south-western Europe. It is thus an important key fossil for the understanding of human evolution in Europe during the Middle Pleistocene, a time period when a great morphological diversity is observed but whose phylogenetic meaning is not yet fully understood.
Assuntos
Fósseis , Datação Radiométrica , Evolução Biológica , Cavernas , Humanos , Úmero , EspanhaRESUMO
OBJECTIVES: The study focuses on the estimation of demographic parameters of Late Neolithic/Early Chalcolithic (mid 4th-early 3rd millenniums cal. BC) burial sites from the La Rioja region (Ebro valley, northern Spain) to identify demographic characteristics. MATERIALS AND METHODS: The human remains come from three caves (Las Yurdinas II, Peña Larga, and La Peña de Marañón) and three megalithic graves (Alto de la Huesera, San Martín, and Peña Guerra II). The total skeletal sample consists of a minimum of 261 individuals, 149 being buried in caves and 112 in megalithic graves. Data based on age and sex estimation are analyzed using abridged life tables, mortality rates, and sex ratios. RESULTS: A systematic bias against children under 5 years of age is detected both in caves (5 q0 = 187.92%) and megalithic graves (5 q0 = 71.43%) but also against some juveniles and adults compared with population models, though a statistically significant greater lack of infants is worth noting in the megaliths (t-test, P = 0.012). Moreover, a significant divergence in sex ratios (χ(2) , P = 0.002) is also identified between site types, clearly prioritizing women in caves (sex ratio = 0.45) and men in megalithic graves (sex ratio = 1.33). CONCLUSIONS: This evidence is interpreted as the result of different selective burial patterns. The mortuary variability could lie behind intragroup differential status relationships, though the hypothesis of two populations performing distinct funerary practices in a small region cannot be rejected at the present state of the research. Am J Phys Anthropol 160:284-297, 2016. © 2016 Wiley Periodicals, Inc.
Assuntos
Sepultamento/história , Sepultamento/estatística & dados numéricos , Cavernas , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Arqueologia , Sepultamento/métodos , Criança , Pré-Escolar , Feminino , História Antiga , Humanos , Lactente , Recém-Nascido , Masculino , Pessoa de Meia-Idade , Espanha , Adulto JovemRESUMO
BACKGROUND: Copy Number Variants (CNVs) contribute to a large fraction of genetic diversity and some of them have been reported to offer an evolutionary advantage. AIM: To identify CNVs in pigmentary loci that could contribute to human skin pigmentation diversity. SUBJECTS AND METHODS: This study assessed the existence of CNVs in every exon of candidate genes: TYR, TYRP1, DCT, MC1R and SLC24A5, using the Multiplex Amplifiable Probe Hybridization technique (MAPH). This study analysed a total of 99 DNA samples of unrelated individuals from different populations. Validation and further analysis in a larger Spanish sample were performed by RT-qPCR. RESULTS: Five CNVs were identified by MAPH: DCT exons 4 and 8, TYR exon 1 and SLC24A5 exons 1 and 4. Real-time quantitative PCR (RT-qPCR) confirmed the CNV in exon 1 of SLC24A5. This study further analysed the 5' promoter region of SLC24A5 and found another CNV in this region. However, no association was found between the CNV and the degree of pigmentation. CONCLUSION: Although the functional role of these structural variants in pigmentation should be the subject of future work, the results emphasize the need to consider all classes of variation (both SNPs and CNVs) when exploring the genetics of skin pigmentation.
Assuntos
Variações do Número de Cópias de DNA/genética , Dosagem de Genes/genética , Melanócitos/enzimologia , Pigmentação da Pele/genética , Adolescente , Adulto , Antiporters/genética , Povo Asiático/genética , Sequência de Bases , Sítios de Ligação/genética , População Negra/genética , Feminino , Humanos , Oxirredutases Intramoleculares/genética , Masculino , Melanócitos/citologia , Glicoproteínas de Membrana/genética , Pessoa de Meia-Idade , Monofenol Mono-Oxigenase/genética , Técnicas de Amplificação de Ácido Nucleico , Oxirredutases/genética , Polimorfismo de Nucleotídeo Único/genética , Reação em Cadeia da Polimerase em Tempo Real , Receptor Tipo 1 de Melanocortina/genética , Análise de Sequência de DNA , População Branca/genética , Adulto JovemRESUMO
In humans, the geographical apportionment of the coding diversity of the pigmentary locus melanocortin-1 receptor (MC1R) is, unusually, higher in Eurasians than in Africans. This atypical observation has been interpreted as the result of purifying selection due to functional constraint on MC1R in high UV-B radiation environments. By analyzing 3,142 human MC1R alleles from different regions of Spain in the context of additional haplotypic information from the 1000 Genomes (1000G) Project data, we show that purifying selection is also strong in southern Europe, but not so in northern Europe. Furthermore, we show that purifying and positive selection act simultaneously on MC1R. Thus, at least in Spain, regions at opposite ends of the incident UV-B radiation distribution show significantly different frequencies for the melanoma-risk allele V60L (a mutation also associated to red hair and fair skin and even blonde hair), with higher frequency of V60L at those regions of lower incident UV-B radiation. Besides, using the 1000G south European data, we show that the V60L haplogroup is also characterized by an extended haplotype homozygosity (EHH) pattern indicative of positive selection. We, thus, provide evidence for an adaptive value of human skin depigmentation in Europe and illustrate how an adaptive process can simultaneously help to maintain a disease-risk allele. In addition, our data support the hypothesis proposed by Jablonski and Chaplin (Human skin pigmentation as an adaptation to UVB radiation. Proc Natl Acad Sci U S A. 2010;107:8962-8968), which posits that habitation of middle latitudes involved the evolution of partially depigmented phenotypes that are still capable of suitable tanning.
Assuntos
Melanoma/genética , Receptor Tipo 1 de Melanocortina/genética , Seleção Genética , Pigmentação da Pele/genética , População Branca/genética , Alelos , Evolução Molecular , Predisposição Genética para Doença , Variação Genética , Haplótipos , Homozigoto , Humanos , Mutação , Fenótipo , Pigmentação da Pele/efeitos da radiação , Espanha , Raios Ultravioleta/efeitos adversosRESUMO
BACKGROUND: In the present study we have assessed whether the Carpathian Mountains represent a genetic barrier in East Europe. Therefore, we have analyzed the mtDNA of 128 native individuals of Romania: 62 of them from the North of Romania, and 66 from South Romania. RESULTS: We have analyzed their mtDNA variability in the context of other European and Near Eastern populations through multivariate analyses. The results show that regarding the mtDNA haplogroup and haplotype distributions the Romanian groups living outside the Carpathian range (South Romania) displayed some degree of genetic differentiation compared to those living within the Carpahian range (North Romania). CONCLUSION: The main differentiation between the mtDNA variability of the groups from North and South Romania can be attributed to the demographic movements from East to West (prehistoric or historic) that differently affected in these regions, suggesting that the Carpathian mountain range represents a weak genetic barrier in South-East Europe.
Assuntos
Genética Populacional , População Branca/genética , DNA Mitocondrial/genética , Haplótipos , Humanos , RomêniaRESUMO
Adequate responses by our innate immune system toward invading pathogens were of vital importance for surviving infections, especially before the antibiotic era. Recently, a polymorphism in Mal (Ser180Leu, TIRAP rs8177374), an important adaptor protein downstream of the Toll-like receptor (TLR) 2 and 4 pathways, has been described to provide protection against a broad range of infectious pathogens. We assessed the functional effects of this polymorphism in human experimental endotoxemia, and we demonstrate that individuals bearing the TIRAP 180L allele display an increased, innate immune response to TLR4 and TLR2 ligands, but not to TLR9 stimulation. This phenotype has been related to an increased resistance to infection. However, an overshoot in the release of proinflammatory cytokines by TIRAP 180L homozygous individuals suggests a scenario of balanced evolution. We have also investigated the worldwide distribution of the Ser180Leu polymorphism in 14 populations around the globe to correlate the genetic makeup of TIRAP with the local infectious pressures. Based on the immunological, clinical, and genetic data, we propose that this mutation might have been selected in West Eurasia during the early settlement of this region after the out-of-Africa migration of modern Homo sapiens. This combination of functional and genetic data provides unique insights to our understanding of the pathogenesis of sepsis.
Assuntos
Endotoxemia/genética , Endotoxemia/imunologia , Glicoproteínas de Membrana/fisiologia , Receptores de Interleucina-1/fisiologia , Seleção Genética , Choque Séptico/genética , Choque Séptico/imunologia , Alelos , Humanos , Imunidade Inata/genética , Leucina/genética , Glicoproteínas de Membrana/genética , Polimorfismo Genético , Receptores de Interleucina-1/genética , Serina/genéticaRESUMO
BACKGROUND/AIM: TP53 is an efficient central node in a signal transduction network that responds to minimize cancer. However, over 50% of tumors show some mutation in TP53. Thus, one might argue that this single central node network lacks robustness. Therefore, we wanted to investigate if natural selection has played a role in shaping the genomic region containing TP53. METHODS: We have analyzed the HapMap data for evidence of selection using F(ST) pairwise comparisons and the extended haplotype homozygosity test on a 200-kb region encompassing TP53. We have also resequenced 4 kb upstream TP53 in Europeans (including melanoma patients), Asians, Australian Aborigines and Africans. RESULTS: Genetic hitchhiking by a linked, positively selected allele at the nearby gene WDR79 may be partly responsible for the sequence diversity profile of TP53. It can help explain why the TP53 Arg72 allele is the major allele in Europeans even when the alternative allele, 72Pro, has been reported to offer an increased longevity after disease. CONCLUSIONS: Despite the important role of TP53, a complex interplay with other evolutionary forces, which are extrinsic to TP53 function, may have driven the genetic diversity pattern of this locus, and, as a consequence, its structure and function.
Assuntos
Variação Genética , Proteínas/genética , Seleção Genética , Proteína Supressora de Tumor p53/genética , Alelos , Povo Asiático/genética , População Negra/genética , Frequência do Gene , Predisposição Genética para Doença/etnologia , Predisposição Genética para Doença/genética , Genótipo , Haplótipos , Humanos , Melanoma/etnologia , Melanoma/genética , Chaperonas Moleculares , Mutação , Havaiano Nativo ou Outro Ilhéu do Pacífico/genética , Polimorfismo de Nucleotídeo Único , Telomerase , População Branca/genéticaRESUMO
Few complete human genomes from the European Early Upper Palaeolithic (EUP) have been sequenced. Using novel sampling and DNA extraction approaches, we sequenced the genome of a woman from "Pestera Muierii," Romania who lived â¼34,000 years ago to 13.5× coverage. The genome shows similarities to modern-day Europeans, but she is not a direct ancestor. Although her cranium exhibits both modern human and Neanderthal features, the genome shows similar levels of Neanderthal admixture (â¼3.1%) to most EUP humans but only half compared to the â¼40,000-year-old Pestera Oase 1. All EUP European hunter-gatherers display high genetic diversity, demonstrating that the severe loss of diversity occurred during and after the Last Glacial Maximum (LGM) rather than just during the out-of-Africa migration. The prevalence of genetic diseases is expected to increase with low diversity; however, pathogenic variant load was relatively constant from EUP to modern times, despite post-LGM hunter-gatherers having the lowest diversity ever observed among Europeans.
Assuntos
Homem de Neandertal , Animais , Emigração e Imigração , Europa (Continente) , Feminino , Genoma Humano , Humanos , Recém-Nascido , Homem de Neandertal/genética , CrânioRESUMO
We investigate the contribution of overdominance to the maintenance of polymorphism in the human genome during the recent evolution of our species. Using the HapMap genotypic information, we have detected that the Gene Ontology term "olfactory receptor activity" is a molecular function overrepresented in genes that have SNPs (Single Nucleotide Polymorphisms) showing higher than expected number of heterozygotes in the HapMap populations. Our results suggest that the diversity of a subset of human olfactory receptors (ORs) may have been maintained by balancing selection, in the form of overdominance. This observation may suggest that the loss of OR genes during the evolution of the human lineage may have been accompanied by an increased capability to discriminate odorants with closely similar structures.
Assuntos
Evolução Molecular , Genoma Humano , Polimorfismo de Nucleotídeo Único , Receptores Odorantes/genética , Seleção Genética , Simulação por Computador , Bases de Dados Genéticas , Heterozigoto , Humanos , PseudogenesRESUMO
BACKGROUND: The observed correlation between ultraviolet light incidence and skin color, together with the geographical apportionment of skin reflectance among human populations, suggests an adaptive value for the pigmentation of the human skin. We have used Affymetrix U133a v2.0 gene expression microarrays to investigate the expression profiles of a total of 9 melanocyte cell lines (5 from lightly pigmented donors and 4 from darkly pigmented donors) plus their respective unirradiated controls. In order to reveal signatures of selection in loci with a bearing on skin pigmentation in humans, we have resequenced between 4 to 5 kb of the proximal regulatory regions of three of the most differently expressed genes, in the expectation that variation at regulatory regions might account for intraespecific morphological diversity, as suggested elsewhere. RESULTS: Contrary to our expectations, expression profiles did not cluster the cells into unirradiated versus irradiated melanocytes, or into lightly pigmented versus darkly pigmented melanocytes. Instead, expression profiles correlated with the presence of Bovine Pituitary Extract (known to contain alpha-MSH) in the media. This allowed us to differentiate between melanocytes that are synthesizing melanin and those that are not. TYR, TYRP1 and DCT were among the five most differently expressed genes between these two groups. Population genetic analyses of sequence haplotypes of the proximal regulatory flanking-regions included Tajima's D, HEW and DHEW neutrality tests analysis. These were complemented with EHH tests (among others) in which the significance was obtained by a novel approach using extensive simulations under the coalescent model with recombination. We observe strong evidence for positive selection for TYRP1 alleles in Africans and for DCT and TYRP1 in Asians. However, the overall picture reflects a complex pattern of selection, which might include overdominance for DCT in Europeans. CONCLUSION: Diversity patterns clearly evidence adaptive selection in pigmentation genes in Africans and Asians. In Europeans, the evidence is more complex, and both directional and balancing selection may be involved in light skin. As a result, different non-African populations may have acquired light skin by alternative ways, and so light skin, and perhaps dark skin too, may be the result of convergent evolution.
Assuntos
Oxirredutases Intramoleculares/genética , Melanócitos/efeitos da radiação , Glicoproteínas de Membrana/genética , Oxirredutases/genética , Pigmentação da Pele/genética , Tirosina/genética , Raios Ultravioleta , Povo Asiático/genética , População Negra/genética , Células Cultivadas , Pré-Escolar , Perfilação da Expressão Gênica , Haplótipos , Humanos , Lactente , Masculino , Análise de Sequência com Séries de Oligonucleotídeos , Reação em Cadeia da Polimerase , Seleção Genética , Análise de Sequência de DNA , Pigmentação da Pele/efeitos da radiação , População Branca/genéticaRESUMO
The present study is focused on a group of arthropathies that may have very similar bone manifestations (rheumatoid arthritis, ankylosing spondylitis, reactive arthritis, psoriatic arthritis, osteoarthritis and diffuse idiopathic skeletal hyperostosis), which makes it more difficult to diagnose them in human remains from archaeological contexts. A stepwise recording form was designed in order to improve the identification and differential diagnosis of these pathological conditions in bone remains, particularly in joint manifestations of the spine, pelvis, hands, feet and other limb joints. This recording form was applied in the analysis of two medieval individuals from the Basque Country (Spain) who presented very severe arthropathic manifestations. The use of this recording form allowed the researchers the diagnosis of ankylosing spondylitis in one of them and diffuse idiopathic skeletal hyperostosis in the other.
Assuntos
Artrite Reumatoide/história , Hiperostose Esquelética Difusa Idiopática/história , Artropatias/história , Paleopatologia , Espondiloartropatias/história , Espondilite Anquilosante/história , Adulto , Artrite Reumatoide/diagnóstico , Artrite Reumatoide/patologia , Osso e Ossos/patologia , Diagnóstico Diferencial , História Medieval , Humanos , Hiperostose Esquelética Difusa Idiopática/diagnóstico , Hiperostose Esquelética Difusa Idiopática/patologia , Artropatias/diagnóstico , Artropatias/patologia , Masculino , Pessoa de Meia-Idade , Paleopatologia/métodos , Paleopatologia/normas , Registros , Espanha , Espondiloartropatias/diagnóstico , Espondiloartropatias/patologia , Espondilite Anquilosante/diagnóstico , Espondilite Anquilosante/patologiaRESUMO
There is a trend to consider the gene pool of the Basques as a 'living fossil' of the earliest modern humans that colonized Europe. To investigate this assumption, we have typed 45 binary markers and five short tandem repeat loci of the Y chromosome in a set of 168 male Basques. Results on these combined haplotypes were analyzed in the context of matching data belonging to approximately 3000 individuals from over 20 European, Near East and North African populations, which were compiled from the literature. Our results place the low Y-chromosome diversity of Basques within the European diversity landscape. This low diversity seems to be the result of a lower effective population size maintained through generations. At least some lineages of Y chromosome in modern Basques originated and have been evolving since pre-Neolithic times. However, the strong genetic drift experienced by the Basques does not allow us to consider Basques either the only or the best representatives of the ancestral European gene pool. Contrary to previous suggestions, we do not observe any particular link between Basques and Celtic populations beyond that provided by the Paleolithic ancestry common to European populations, nor we find evidence supporting Basques as the focus of major population expansions.
Assuntos
Cromossomos Humanos Y , Variação Genética , Europa (Continente) , Marcadores Genéticos , Humanos , MasculinoRESUMO
The extraction of DNA from human skeletal remains applied to forensic, and evolutionary studies do not exclude risks, which are to be evaluated when working with unique specimens that could be damaged or even destroyed. In the present study were evaluated several nondestructive methods for recovering DNA instead of the most currently used pulverization method. Three different procedures to access inside the dental pieces (occlusal perforation, cervical perforation, and cervical cut) have been compared with the aim of recovering as many cell remains as possible to carry out a DNA extraction. Given the DNA quantitation results, a method was proposed that consists of a cervical cut to facilitate the access to the pulp cavity and a subsequent filing of the root canals down to the apex of the dental root. This methodology allows the recovery of both mitochondrial and nuclear DNA, with the minimum deterioration for the dental pieces.
Assuntos
DNA Mitocondrial/isolamento & purificação , Manejo de Espécimes/métodos , Raiz Dentária/química , Dente Canino , Impressões Digitais de DNA , Polpa Dentária/química , Odontologia Legal , Humanos , Dente Serotino , Reação em Cadeia da PolimeraseRESUMO
The importance of the process of Neolithization for the genetic make-up of European populations has been hotly debated, with shifting hypotheses from a demic diffusion (DD) to a cultural diffusion (CD) model. In this regard, ancient DNA data from the Balkan Peninsula, which is an important source of information to assess the process of Neolithization in Europe, is however missing. In the present study we show genetic information on ancient populations of the South-East of Europe. We assessed mtDNA from ten sites from the current territory of Romania, spanning a time-period from the Early Neolithic to the Late Bronze Age. mtDNA data from Early Neolithic farmers of the Starcevo Cris culture in Romania (Cârcea, Gura Baciului and Negrilesti sites), confirm their genetic relationship with those of the LBK culture (Linienbandkeramik Kultur) in Central Europe, and they show little genetic continuity with modern European populations. On the other hand, populations of the Middle-Late Neolithic (Boian, Zau and Gumelnita cultures), supposedly a second wave of Neolithic migration from Anatolia, had a much stronger effect on the genetic heritage of the European populations. In contrast, we find a smaller contribution of Late Bronze Age migrations to the genetic composition of Europeans. Based on these findings, we propose that permeation of mtDNA lineages from a second wave of Middle-Late Neolithic migration from North-West Anatolia into the Balkan Peninsula and Central Europe represent an important contribution to the genetic shift between Early and Late Neolithic populations in Europe, and consequently to the genetic make-up of modern European populations.
Assuntos
DNA Mitocondrial/genética , Variação Genética , Genética Populacional , Geografia , Haplótipos/genética , Humanos , Análise Multivariada , Análise de Componente Principal , Romênia , Fatores de TempoRESUMO
We analysed the whole-genome transcriptional profile of 6 cell lines of dark melanocytes (DM) and 6 of light melanocytes (LM) at basal conditions and after ultraviolet-B (UVB) radiation at different time points to investigate the mechanisms by which melanocytes protect human skin from the damaging effects of UVB. Further, we assessed the effect of different keratinocyte-conditioned media (KCM+ and KCM-) on melanocytes. Our results suggest that an interaction between ribosomal proteins and the P53 signaling pathway may occur in response to UVB in both DM and LM. We also observed that DM and LM show differentially expressed genes after irradiation, in particular at the first 6h after UVB. These are mainly associated with inflammatory reactions, cell survival or melanoma. Furthermore, the culture with KCM+ compared with KCM- had a noticeable effect on LM. This effect includes the activation of various signaling pathways such as the mTOR pathway, involved in the regulation of cell metabolism, growth, proliferation and survival. Finally, the comparison of the transcriptional profiles between LM and DM under basal conditions, and the application of natural selection tests in human populations allowed us to support the significant evolutionary role of MIF and ATP6V0B in the pigmentary phenotype.
Assuntos
Perfilação da Expressão Gênica/métodos , Melanócitos/efeitos da radiação , Transcriptoma/efeitos da radiação , Raios Ultravioleta , Células Cultivadas , Humanos , Melanócitos/citologia , Melanócitos/metabolismo , Análise de Sequência com Séries de Oligonucleotídeos , Análise de Componente Principal , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transdução de Sinais/genética , Transdução de Sinais/efeitos da radiação , Pele/citologia , Pele/metabolismo , Pigmentação da Pele/genéticaRESUMO
We explore different designs to estimate both nuclear and mitochondrial human DNA (mtDNA) content based on the detection of the 5' nuclease activity of the Taq DNA polymerase using fluorogenic probes and a real-time quantitative PCR detection system. Human mtDNA quantification was accomplished by monitoring the real-time progress of the PCR-amplification of two different fragment sizes (113 and 287 bp) within the hypervariable region I (HV1) of the mtDNA control region, using two fluorogenic probes to specifically determine the mtDNA copy of each fragment size category. This mtDNA real-time PCR design has been used to assess the mtDNA preservation (copy number and degradation state) of DNA samples retrieved from 500 to 1500 years old human remains that showed low copy number and highly degraded mtDNA. The quantification of nuclear DNA was achieved by real-time PCR of a segment of the X-Y homologous amelogenin (AMG) gene that allowed the simultaneous estimation of a Y-specific fragment (AMGY: 112 bp) and a X-specific fragment (AMGX: 106 bp) making possible not only haploid or diploid DNA quantitation but also sex determination. The AMG real-time PCR design has been used to quantify a set of 57 DNA samples from 4-5 years old forensic bone remains with improved sensitivity compared with the slot-blot hybridization method. The potential utility of this technology to improve the quality of some PCR-based forensic and ancient DNA studies (microsatellite typing and mtDNA sequencing) is discussed.
Assuntos
Impressões Digitais de DNA/métodos , DNA/análise , Dosagem de Genes , Reação em Cadeia da Polimerase/métodos , Amelogenina , Animais , Núcleo Celular/genética , Proteínas do Esmalte Dentário/genética , Feminino , Antropologia Forense/métodos , Hominidae/genética , Humanos , Masculino , Análise para Determinação do Sexo , Sequências de Repetição em Tandem , Germe de DenteRESUMO
Haplotype, allele frequencies and population data of 11 Y-chromosome STR loci DYS19, DYS385, DYS389I, DYS389II, DYS390, DYS391, DYS392, DYS393, DYS438 and DYS439 were determined from a sample of 168 unrelated autochthonous male individuals from the Basque Country. The eight surnames and birth places of the grandparents of all analyzed individuals were of Basque origin. A total of 89 haplotypes were identified by the 11 Y-STR loci. The haplotype diversity (97.49%) and discrimination capacity (52.98%) were calculated. Comparisons were made with previously published haplotype data on other Iberian population samples and significant differences were found.
Assuntos
Cromossomos Humanos Y , Frequência do Gene , Genética Populacional , Haplótipos , Sequências de Repetição em Tandem , Impressões Digitais de DNA/métodos , Humanos , Homens , Reação em Cadeia da Polimerase , EspanhaRESUMO
We aimed to study the selective pressures interacting on SLC45A2 to investigate the interplay between selection and susceptibility to disease. Thus, we enrolled 500 volunteers from a geographically limited population (Basques from the North of Spain) and by resequencing the whole coding region and intron 5 of the 34 most and the 34 least pigmented individuals according to the reflectance distribution, we observed that the polymorphism Leu374Phe (L374F, rs16891982) was statistically associated with skin color variability within this sample. In particular, allele 374F was significantly more frequent among the individuals with lighter skin. Further genotyping an independent set of 558 individuals of a geographically wider population with known ancestry in the Spanish population also revealed that the frequency of L374F was significantly correlated with the incident UV radiation intensity. Selection tests suggest that allele 374F is being positively selected in South Europeans, thus indicating that depigmentation is an adaptive process. Interestingly, by genotyping 119 melanoma samples, we show that this variant is also associated with an increased susceptibility to melanoma in our populations. The ultimate driving force for this adaptation is unknown, but it is compatible with the vitamin D hypothesis. This shows that molecular evolution analysis can be used as a useful technology to predict phenotypic and biomedical consequences in humans.
Assuntos
Alelos , Antígenos de Neoplasias/genética , Predisposição Genética para Doença , Melanoma/genética , Proteínas de Membrana Transportadoras/genética , Seleção Genética , População Branca/genética , Europa (Continente) , Frequência do Gene , Interação Gene-Ambiente , Haplótipos , Humanos , Fases de Leitura Aberta , Polimorfismo de Nucleotídeo Único , Característica Quantitativa Herdável , Análise de Sequência de DNA , EspanhaRESUMO
BACKGROUND: Caspase-12 (CASP12) modulates the susceptibility to sepsis. In humans, the "C" allele at CASP12 rs497116 has been associated with an increased risk of sepsis. Instead, the derived "T" allele encodes for an inactive caspase-12. Interestingly, Eurasians are practically fixed for the inactive variant, whereas in Sub-Saharan Africa the active variant is still common (~24%). This marked structure has been explained as a function of the selective advantage that the inactive caspase-12 confers by increasing resistance to infection. As regards to both when positive selection started acting and as to the speed with which fixation was achieved in Eurasia, estimates depend on the method and assumptions used, and can vary substantially. Using experimental evidence, we propose that, least in Eurasia, the increase in the frequency of the T allele might be related to the selective pressure exerted by the increase in zoonotic diseases transmission caused by the interplay between increased human population densities and a closer contact with animals during the Neolithic. METHODOLOG/PRINCIPAL FINDINGS: We genotyped CASP12 rs497116 in prehistoric individuals from 6 archaeological sites from the North of the Iberian Peninsula that date from Late Upper Paleolithic to Late Neolithic. DNA extraction was done from teeth lacking cavities or breakages using standard anti-contamination procedures, including processing of the samples in a positive pressure, ancient DNA-only chamber, quantitation of DNAs by qPCR, duplication, replication, genotyping of associated animals, or cloning of PCR products. Out of 50, 24 prehistoric individuals could finally be genotyped for rs497116. Only the inactive form of CASP12 was found. CONCLUSIONS/SIGNIFICANCE: We demonstrate that the loss of caspase-12 in Europe predates animal domestication and that consequently CASP12 loss is unlikely to be related to the impact of zoonotic infections transmitted by livestock.