RESUMEN
Drosophila, Arabidopsis, Synechocystis, human (DASH)-type cryptochromes (cry-DASHs) form one subclade of the cryptochrome/photolyase family (CPF). CPF members are flavoproteins that act as DNA-repair enzymes (DNA-photolyases), or as ultraviolet(UV)-A/blue light photoreceptors (cryptochromes). In mammals, cryptochromes are essential components of the circadian clock feed-back loop. Cry-DASHs are present in almost all major taxa and were initially considered as photoreceptors. Later studies demonstrated DNA-repair activity that was, however, restricted to UV-lesions in single-stranded DNA. Very recent studies, particularly on microbial organisms, substantiated photoreceptor functions of cry-DASHs suggesting that they could be transitions between photolyases and cryptochromes.
Asunto(s)
Arabidopsis/metabolismo , Criptocromos/metabolismo , Desoxirribodipirimidina Fotoliasa/metabolismo , Drosophila/metabolismo , Synechocystis/metabolismo , Animales , HumanosRESUMEN
This study provides 398 novel complete mitochondrial control region sequences that augment the still underrepresented data from Africa by three datasets: a mixed West African sample set deriving from 12 countries (nâ¯=â¯145) and datasets from Côte d'Ivoire (Ivory Coast) (nâ¯=â¯100) as well as Rwanda (nâ¯=â¯153). The analysis of mtDNA variation and genetic comparisons with published data revealed low random match probabilities in all three datasets and typical West African and East African diversity, respectively. Genetic parameters indicate that the presented mixed West African dataset may serve as first forensic mtDNA control region database for West Africa in general. In addition, a strategy for responsible forensic application of precious mtDNA population samples potentially containing close maternal relatives is outlined. The datasets will be uploaded to the forensic mtDNA database EMPOP (https://empop.online) upon publication.
Asunto(s)
ADN Mitocondrial/genética , Variación Genética , Genética de Población , África Occidental , Población Negra/genética , Côte d'Ivoire , Conjuntos de Datos como Asunto , Haplotipos , Humanos , Región de Control de Posición , RwandaRESUMEN
Members of the cryptochrome/photolyase family (CPF) of proteins utilize noncovalently bound light-absorbing cofactors for their biological function. Usually, the identity of these cofactors is determined after expression in heterologous systems leaving the question unanswered whether these cofactors are identical to the indigenous ones. Here, cryptochrome 3 from Arabidopsis thaliana was expressed as a fusion with the green fluorescent protein in Arabidopsis plants. Besides the confirmation of the earlier report of its localization in chloroplasts, our data indicate that fractions of the fusion protein are present in the stroma and associated with thylakoids, respectively. Furthermore, it is shown that the fusion protein expressed in planta contains the same cofactors as the His6 -tagged protein expressed in Escherichia coli, that is, flavin adenine dinucleotide and N5 ,N10 -methenyltetrahydrofolate. This demonstrates that the heterologously expressed cryptochrome 3, characterized in a number of previous studies, is a valid surrogate of the corresponding protein expressed in plants. To our knowledge, this is also a first conclusive analysis of cofactors bound to an Arabidopsis protein belonging to the CPF and purified from plant tissue.
Asunto(s)
Arabidopsis/enzimología , Criptocromos/metabolismo , Flavina-Adenina Dinucleótido/metabolismo , Tetrahidrofolatos/metabolismo , Cromatografía de Fase Inversa , Criptocromos/genética , Escherichia coli/genética , Proteínas Fluorescentes Verdes/genética , Proteínas Fluorescentes Verdes/metabolismo , Inmunoprecipitación , Plantas Modificadas Genéticamente , Proteínas Recombinantes de Fusión/genética , Proteínas Recombinantes de Fusión/metabolismo , Espectrometría de FluorescenciaRESUMEN
Africa is the cradle of all human beings, and although it has been the focus of a number of genetic studies, there are many questions that remain unresolved. We have performed one of the largest and most comprehensive meta-analyses of mitochondrial DNA (mtDNA) lineages carried out in the African continent to date. We generated high-throughput mtDNA single nucleotide polymorphism (SNP) data (230 SNPs) from 2024 Africans, where more than 500 of them were additionally genotyped for the control region. These data were analyzed together with over 12,700 control region profiles collected from the literature, representing more than 300 population samples from Africa. Insights into the African homeland of humans are discussed. Phylogeographic patterns for the African continent are shown at a high phylogeographic resolution as well as at the population and regional levels. The deepest branch of the mtDNA tree, haplogroup L0, shows the highest sub-haplogroup diversity in Southeast and East Africa, suggesting this region as the homeland for modern humans. Several demographic estimates point to the coast as a facilitator of human migration in Africa, but the data indicate complex patterns, perhaps mirroring the effect of recent continental-scaled demographic events in re-shaping African mtDNA variability.
Asunto(s)
Población Negra/genética , ADN Mitocondrial/genética , Demografía , Polimorfismo de Nucleótido Simple , Teorema de Bayes , Migración Humana , Humanos , FilogeniaRESUMEN
In forensic genetics mitochondrial DNA (mtDNA) is usually analyzed by direct Sanger-type sequencing (STS). This method is known to be laborious and sometimes prone to human error. Alternative methods have been proposed that lead to faster results. Among these are methods that involve mass-spectrometry resulting in base composition profiles that are, by definition, less informative than the full nucleotide sequence. Here, we applied a highly automated electrospray ionization mass spectrometry (ESI-MS) system (PLEX-ID) to an mtDNA population study to compare its performance with respect to throughput and concordance to STS. We found that the loss of information power was relatively low compared to the gain in speed and analytical standardization. The detection of point and length heteroplasmy turned out to be roughly comparable between the technologies with some individual differences related to the processes. We confirm that ESI-MS provides a valuable platform for analyzing mtDNA variation that can also be applied in the forensic context.
Asunto(s)
ADN Mitocondrial/genética , Bases de Datos Genéticas , Genética Forense , Espectrometría de Masa por Ionización de Electrospray/métodos , Composición de Base , HumanosRESUMEN
West Africa is characterized by a migration history spanning more than 150,000 years. Climate changes but also political circumstances were responsible for several early but also recent population movements that shaped the West African mitochondrial landscape. The aim of the study was to establish a Ghanaian mtDNA dataset for forensic purposes and to investigate the diversity of the Ghanaian population sample with respect to surrounding populations. We sequenced full mitochondrial control regions of 193 Akan people from Ghana and excluded two apparently close maternally related individuals due to preceding kinship testing. The remaining dataset comprising 191 sequences was applied as etalon for quasi-median network analysis and was subsequently combined with 99 additional control region sequences from surrounding West African countries. All sequences were incorporated into the EMPOP database enriching the severely underrepresented African mtDNA pool. For phylogeographic considerations, the Ghanaian haplotypes were compared to those of 19 neighboring populations comprising a total number of 6198 HVS1 haplotypes. We found extensive genetic admixture between the Ghanaian lineages and those from adjacent populations diminishing with geographical distance. The extent of genetic admixture reflects the long but also recent history of migration waves within West Africa mainly caused by changing environmental conditions. Also, evidence for potential socio-economical influences such as trade routes is provided by the occurrence of U6b and U6d sequences found in Dubai but also in Tunisia leading to the African West Coast via Mauritania and Senegal but also via Niger, Nigeria to Cameroon.
Asunto(s)
ADN Mitocondrial/genética , Variación Genética , Genética de Población , Adolescente , Adulto , Dermatoglifia del ADN , Ghana , Haplotipos , Humanos , Repeticiones de Microsatélite , Persona de Mediana Edad , Filogeografía , Análisis de Secuencia de ADN , Adulto JovenRESUMEN
BACKGROUND: Nearly half of the West Eurasian assemblage of human mitochondrial DNA (mtDNA) is fractioned into numerous sub-lineages of the predominant haplogroup (hg) R0. Several hypotheses have been proposed on the origin and the expansion times of some R0 sub-lineages, which were partially inconsistent with each other. Here we describe the phylogenetic structure and genetic variety of hg R0 in five European populations and one population from the Middle East. RESULTS: Our analysis of 1,350 mtDNA haplotypes belonging to R0, including entire control region sequences and 45 single nucleotide polymorphisms from the coding region, revealed significant differences in the distribution of different sub-hgs even between geographically closely located regions. Estimates of coalescence times that were derived using diverse algorithmic approaches consistently affirmed that the major expansions of the different R0 hgs occurred in the terminal Pleistocene and early Holocene. CONCLUSION: Given an estimated coalescence time of the distinct lineages of 10-18 kya, the differences in the distributions could hint to either limited maternal gene flow after the Last Glacial Maximum due to the alpine nature of the regions involved or to a stochastic loss of diversity due to environmental events and/or disease episodes occurred at different times and in distinctive regions. Our comparison of two different ways of obtaining the timing of the most recent common ancestor confirms that the time of a sudden expansion can be adequately recovered from control region data with valid confidence intervals. For reliable estimates, both procedures should be applied in order to cross-check the results for validity and soundness.
Asunto(s)
ADN Mitocondrial/genética , Variación Genética/genética , Haplotipos/genética , Disparidad de Par Base , Europa (Continente)/etnología , Genética de Población , Humanos , Medio Oriente/etnología , Filogenia , Polimorfismo de Nucleótido Simple , Dinámica PoblacionalRESUMEN
Recently, a metric approach to skeletal sex determination was published by Paiva and Segre which is based on the summation of two triangular areas defined by three distinct craniometric landmarks: Porion, Mastoidale, and Asterion. According to the authors, values for the total triangle > or =1447.40 mm(2) are characteristic for male crania, while values < or =1260.36 mm(2) are indicative of female skulls (95% confidence). In order to evaluate the method's validity, two sex- and age-documented samples of different provenience were analyzed (N=197). The results show that while the indicated measurements display significant sex differences, the technique is of little practical meaning where a single individual must be independently classified. It is hypothesized that differences in the expression of sexual dimorphism as well as a population-specific variability of the asterion location undermine the value of the mastoid triangle as a sex determinant.