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Radiocarbon is one of the most widespread radionuclides in nature. Although it is probably best known for dating in archaeology, in the case of the general public, it represents a useful tracer to study our environment, both in the past and nowadays. For instance, carbonaceous particles, which are in many cases the most abundant among aerosols constituents, are believed to play a major role in both health and climatic effects of aerosols. In particular, measurement of radiocarbon concentration in particulate matter samples can give information on the contributions of the fossil fuels combustion and of natural sources to the carbonaceous fraction in aerosols. These measurements are especially effective when separately performed on different carbonaceous fractions, like elemental and organic carbon (EC and OC, respectively). Past climate is also studied thanks to old archives, as e.g. marine sediments can be. In this case, instead of radiocarbon dating the bulk sediment, a reliable method to fix chronological markers is represented by dating foraminifera tests of CaCO3 picked from different layers in the sediment. Both the aforementioned applications are characterized by the fact that the samples that can be collected for 14C measurements are typically very small, i.e. few mg or less (before any treatment). Accelerator Mass Spectrometry (AMS) is thus the only technique that can be applied to measure radiocarbon in such samples. Anyway, measurements cannot be so straightforward. In the case of the measurement of radiocarbon concentration in aerosol samples, a preparation line especially dedicated to the extraction of only the carbonaceous fraction of interest is mandatory. Actually, this line should include a combustion oven, from which either total carbon or EC and OC can separately evolve, and a system of traps to purify and collect the CO2. In the case of foraminifera tests (inorganic carbon), special care must be taken in the pre-treatment phase: foraminifera can be contaminated by heterogeneous materials, including organic matter too. Pre-treatment should thus remove all the possible contaminations without losing too much mass of the samples. Here we present an overview of the environmental radiocarbon applications the INFN-LABEC laboratory in Florence is involved in. 14C is measured by AMS, using the dedicated beam line installed at the 3 MV Tandem accelerator. In particular, details about the hardware and the experimental procedures are given.

The territory of Chile is particularly long and narrow, which combined with its mountainous terrain, makes it a unique scenario for human genetic studies. We obtained 995 control region mitochondrial DNA (mtDNA) sequences from Chileans representing populations living at different latitudes of the country from the North to the southernmost region. The majority of the mtDNA profiles are of Native American origin (∼88%). The remaining haplotypes are mostly of recent European origin (∼11%), and only a minor proportion is of recent African ancestry (∼1%). While these proportions are relatively uniform across the country, more structured patterns of diversity emerge when examining the variation from a phylogeographic perspective. For instance, haplogroup A2 reaches ∼9% in the North, and its frequency decreases gradually to ∼1% in the southernmost populations, while the frequency of haplogroup D (sub-haplogroups D1 and D4) follows the opposite pattern: 36% in the southernmost region, gradually decreasing to 21% in the North. Furthermore, there are remarkable signatures of founder effects in specific sub-clades of Native American (e.g. haplogroups D1j and D4p) and European (e.g. haplogroups T2b3 and K1a4a1a + 195) ancestry. We conclude that the magnitude of the latitudinal differences observed in the patterns of mtDNA variation might be relevant in forensic casework. [ABSTRACT FROM AUTHOR]

We have genotyped 46 Ancestry Informative Markers (AIMs) in two of the most populated areas in Bolivia, namely, La Paz (Andean region; n =105), and Chuquisaca (Sub-Andean region; n =73). Using different analytical tools, we inferred admixture proportions of these two American communities by comparing the genetic profiles with those publicly available from the CEPH (Centre d’Etude du Polymorphisme Humain) panel representing three main continental groups (Africa, Europe, and America). By way of simulations, we first evaluated the minimum sample size needed in order to obtain accurate estimates of ancestry proportions. The results indicated that sample sizes above 30 individuals could be large enough to estimate main continental ancestry proportions using the 46 AIMs panel. With the exception of a few individuals, the results also indicated that Bolivians showed a predominantly Native American ancestry with variable levels of European admixture. The proportions of ancestry were statistically different in La Paz and Chuquisaca: the Native American component was 86% and 77% (Mann–Whitney U-test: un-adjusted P-value=2.1×10−5), while the European ancestry was 13% and 21% (Mann–Whitney U-test: un-adjusted P-value=3.6×10−5), respectively. The African ancestry in Bolivians captured by the AIMs analyzed in the present study was below 2%. The inferred ancestry of Bolivians fits well with previous studies undertaken on haplotype data, indicating a major proportion of Native American lineages. The genetic differences observed in these two groups suggest that forensic genetic analysis should be better performed based on local databases built in the main Bolivian areas. [ABSTRACT FROM AUTHOR]

Abstract: There is a growing interest among forensic geneticists in developing efficient protocols for genotyping coding region mitochondrial DNA (mtDNA) SNPs (mtSNPs). Minisequencing is becoming a popular method for SNP genotyping, but it is still used by few forensic laboratories. In part, this is due to the lack of studies testing its efficiency and reproducibility when applied to real and complex forensic samples. Here we tested a minisequencing design that consists of 71 mtSNPs (in three multiplexes) that are diagnostic of known branches of the R0 phylogeny, in real forensic samples, including degraded bones and teeth, hair shafts, and serial dilutions. The fact that amplicons are short coupled with the natural efficiency of the minisequencing technique allow these assays to perform well with all the samples tested either degraded and/or those containing low DNA amount. We did not observe phylogenetic inconsistencies in the 71 mtSNP haplotypes generated, indicating that the technique is robust against potential artefacts that could arise from unintended contamination and/or spurious amplification of nuclear mtDNA pseudogenes (NUMTs). [Copyright &y& Elsevier]

Abstract: We have developed a single PCR multiplex SNaPshot reaction that consists of 32 coding region SNPs that allows (i) increasing the discrimination power of the mitochondrial DNA (mtDNA) typing in forensic casework, and (ii) haplogroup assignments of mtDNA profiles in both human population studies (e.g. anthropological) and medical research. The selected SNPs target the East Asian phylogeny, including its Native American derived branches. We have validated this multiplex assay by genotyping a sample of East Asians (Taiwanese) and Native Americans (Argentineans). In addition to the coding SNP typing, we have sequenced the complete control region for the same samples. The genotyping results (control region plus SNaPshot profiles) are in good agreement with previous human population genetic studies (based on e.g. complete sequencing) and the known mtDNA phylogeny. We observe that the SNaPshot method is reliable, rapid, and cost effective in comparison with other techniques of multiplex SNP genotyping. We discuss the advantages of our SNP genotyping selection with respect to previous attempts, and we highlight the importance of using the known mtDNA phylogeny as a framework for SNP profile interpretation and as a tool to minimize genotyping errors. [Copyright &y& Elsevier]

Abstract: We here designed a multiplex minisequencing assay for genotyping 71 coding region SNPs of the mitochondrial DNA (mtDNA) genome targeting the most important phylogenetic branches within R0, where the common haplogroup H and its different sub-clades are nested. We present preliminary results related to frequency patterns in Iberia and its performance in typical forensic samples. [Copyright &y& Elsevier]

Abstract: The genetic structure of Italy appears to be mainly shaped by pre-Roman historical events. The studies carried out so far show a major North–South cline, possibly the result of two distinct main demic processes: the first colonisation of the area during the Palaeolithic period and the subsequent Neolithic expansion from the Middle East. However, the demographic contribution of these events is still a matter of debate. We here report mitochondrial DNA (mtDNA) data from nine population groups covering the main Italian regions: Central Liguria (N =50), East Friuli (N =51), South Latium (N =48), Central Marche (N =53), West Calabria (N =50), Central Campania (N =50), South Apulia (N =53), and two populations from Sicily (East and West Sicily, N =40 each). Haplogroup frequency spectra indicate clear differences at a regional level and haplotype sharing among populations is low. [Copyright &y& Elsevier]