Mitogenomics of historical type specimens of Australasian turtles
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ABSTRACT:
PROVIDER: PRJEB31010 | ENA |
REPOSITORIES: ENA
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Project description:Diagnosability is central to taxonomy as are type specimens which define taxa. New advances in technologies and the discovery of new informative traits must be matched with previous taxonomic decisions based on name-bearing type specimens. Consequently, the challenge of sequencing highly degraded DNA from historical types becomes an inevitability to resolve the very many taxonomic issues arising from, by modern standards, poor historical species descriptions leading to difficulties to assign names to genetic clusters identified from fresh material. Here we apply high-throughput parallel sequencing and sequence baiting to reconstruct the mitogenomes from 18 type specimens of Australasian side-necked turtles (Chelidae). We resolve a number of important issues that have confused the taxonomy of this family, and analyse the mitogenomes of the types and those of fresh material to improve our understanding of the phylogenetic relationships of this morphologically conservative group. Together with previously published nuclear genomic data, our study provides evidence for multiple old mitochondrial introgressions.
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Project description:Natural history museum specimens of historical honeybees have been successfully used to explore the genomic past of the honeybee, indicating fast and rapid changes between historical and modern specimens, possibly as a response to current challenges. In our study we explore a potential untapped archive from natural history collections - specimens of beeswax. We examine an Apis mellifera mellifera queen cell specimen from the 19th century. The intact and closed cell was analysed by X-ray Computed Tomography (CT) to reveal a perfectly preserved queen bee inside her cell. Subsequently, a micro-destructive approach was used to evaluate the possibility of protein extraction from the cell. Our results show that studies on specimens such as these provide valuable information about the past rearing of queens, their diet and development, which is relevant for understanding current honeybee behaviour. In addition we evaluate the feasibility of using historical beeswax as a biomolecular archive for ancient proteins to study honeybees.
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Project description:Formalin induces inter- and intra-molecular crosslinks within exposed cells. This cross-linking can be exploited to characterise chromatin state as in the FAIRE (Formaldehyde-Assisted Isolation of Regulatory Elements) and MNase (micrococcal nuclease) assays. Here, we optimised the FAIRE and MNase assays for application upon heavily-fixed tissues as is typically found in historical formalin-preserved museum specimens. We demonstrate these assays in formalin-fixed mouse specimens and compare the chromatin signatures to specimen-matched fresh tissues. We found that heavy formalin fixation modulates rather than eliminates signatures of differential chromatin accessibility and that these chromatin profiles are reproducible, tissue-specific and sex-specific in vertebrate specimens.
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