Biobanks, which contain human biological samples and/or data, provide a crucial contribution to the progress of biomedical research. However, the effective and efficient use of biobank resources depends on their accessibility. In fact, making bio-resources promptly accessible to everybody may increase the benefits for society. Furthermore, optimizing their use and ensuring their quality will promote scientific creativity and, in general, contribute to the progress of bio-medical research. Although this has become a rather common belief, several laboratories are still secretive and continue to withhold samples and data. In this study, we conducted a questionnaire-based survey in order to investigate sample and data accessibility in research biobanks operating all over the world. The survey involved a total of 46 biobanks. Most of them gave permission to access their samples (95.7%) and data (85.4%), but free and unconditioned accessibility seemed not to be common practice. The analysis of the guidelines regarding the accessibility to resources of the biobanks that responded to the survey highlights three issues: (i) the request for applicants to explain what they would like to do with the resources requested; (ii) the role of funding, public or private, in the establishment of fruitful collaborations between biobanks and research labs; (iii) the request of co-authorship in order to give access to their data. These results suggest that economic and academic aspects are involved in determining the extent of sample and data sharing stored in biobanks. As a second step of this study, we investigated the reasons behind the high diversity of requirements to access biobank resources. The analysis of informative answers suggested that the different modalities of resource accessibility seem to be largely influenced by both social context and legislation of the countries where the biobanks operate.

Objectives: Tunisia has been a crossroads for people from Africa, Europe, and the Middle East since prehistoric times. At present, it is inhabited by two main ethnic groups, Arabs and Berbers, and several minorities. This study aims to advance knowledge regarding their genetic structure using new population samplings and a genome-wide approach. Materials and Methods: We investigated genomic variation, estimated ancestry components and dated admixture events in three Berber and two Arab populations from Southern Tunisia, mining a dataset including Middle Eastern, sub-Saharan, and European populations. Results: Differences in the proportion of North African, Arabian, and European ancestries and the varying impact of admixture and isolation determined significant heterogeneity in the genetic structure of Southern Tunisian populations. Admixture time estimates show a multilayer pattern of admixture events, involving both ethnolinguistic groups, which started around the mid XI century and lasted for nearly five centuries. Discussion: Our study provides evidence that the relationships between genetic and cultural diversity of old and new inhabitants of North Africa in southern Tunisia follow different patterns. The Berbers seem to have preserved a significant part of their common genomic heritage despite Islamization, Arab cultural influence, and linguistic diversity. Compared to Morocco and Algeria, southern Tunisian Arabs have retained a higher level of Arabian ancestry. This is more evident in the semi-nomad R'Baya, who have kept their original Bedouin lifestyle, than in the population from Douz, who have undergone multiple events of stratification and admixture.

The Tyrolean Iceman is an extraordinarily well-preserved natural mummy that lived south of the Alpine ridge ~5,200 years before present (ybp), during the Copper Age. Despite studies that have investigated his genetic profile, the relation of the Iceman´s maternal lineage with present-day mitochondrial variation remains elusive. Studies of the Iceman have shown that his mitochondrial DNA (mtDNA) belongs to a novel lineage of haplogroup K1 (K1f) not found in extant populations. We analyzed the complete mtDNA sequences of 42 haplogroup K bearing individuals from populations of the Eastern Italian Alps – putatively in genetic continuity with the Tyrolean Iceman—and compared his mitogenome with a large dataset of worldwide K1 sequences. Our results allow a re-definition of the K1 phylogeny, and indicate that the K1f haplogroup is absent or rare in present-day populations. We suggest that mtDNA Iceman´s lineage could have disappeared during demographic events starting in Europe from ~5,000 ybp. Based on the comparison of our results with published data, we propose a scenario that could explain the apparent contrast between the phylogeographic features of maternal and paternal lineages of the Tyrolean Iceman within the context of the demographic dynamics happening in Europe from 8,000 ybp.

1Biobanks hold human biological samples and/or data giving a crucial contribution to the progress 2 of biomedical research. However, the effective and efficient exploitation of these resources 3 depends on their accessibility. In fact, making bio-resources promptly accessible to all, can 4 favour collaboration among research groups as well as multidisciplinarity. Although this has 5 become a rather common belief, several laboratories still apply secrecy and withholding of 6 samples and data. In this study we conducted a questionnaire based survey in order to investigate 7 sample and data accessibility in research biobanks operating all over the world. 46 out of the 238 8 contacted biobanks have decided to participate. Most of them provide permission to access their 9 samples (95.7%) and data (85.4%), but free and unconditioned accessibility seems not to be a 10 common practice. The analysis of the biobanks guidelines regarding the accessibility of their 11 resources reveal the importance of three aspects: (i) request for applicants to explain what they 12 would like to do with the required resources; (ii) the role of funding, public or private, in the 13 establishment of fruitful collaborations between biobanks and research labs; (iii) request of co-14 authorship in order to give access to their data. These results suggest that economic and academic 15 aspects are involved in determining the extent of sharing of samples and data stored in biobanks. 16As a second step of this study, we investigated the reasons behind the high diversity of the 17 requirements for accessing to biobanks' resources. The analysis of informative answers suggested 18 that the different modalities of resource accessibility seem to be largely influenced by both social 19 context and legislation of the countries where biobanks operate. 20 21Keywords: open science, data sharing, human subjects, research ethics, biorepository. 22 23PeerJ PrePrints | https://dx.doi.org/10.7287/peerj.preprints.1212v1 | CC-BY 4.0 Open Access |

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