Increasing sustainability in palaeoproteomics by optimizing digestion times for large-scale archaeological bone analyses

Palaeoproteomic analysis of skeletal proteomes is used to provide taxonomic identifications for an increasing number of archaeological specimens. The success rate depends on a range of taphonomic factors and differences in the extraction protocols employed. By analyzing 12 archaeological bone specimens from two archaeological sites, we demonstrate that reducing digestion duration from 18 to 3 hours has no measurable impact on the obtained taxonomic identifications. Peptide marker recovery, COL1 sequence coverage, or proteome complexity are also not significantly impacted. Although we observe minor differences in sequence coverage and glutamine deamidation, these are not consistent across our dataset. A 6-fold reduction in digestion time reduces electricity consumption, and therefore CO2 emission intensities. We furthermore demonstrate that working in 96-well plates further reduces electricity consumption by 60%, in comparison to individual microtubes. Reducing digestion time therefore has no impact on the taxonomic identifications, while reducing the environmental impact of palaeoproteomic projects

Afríski hvatberahópurinn L3e5a í íslensku þjóðinni

The genetic composition of Icelanders has been widely researched. For the last couple of decades deCODE genetics in Iceland has collected DNA samples from more than half the Icelandic population. Studies of mitochondrial DNA from the genetic database as well as data from the genealogical database have revealed that the Icelandic population is largely descendant from Scandinavia and the British Isles. However, a small proportion of the Icelandic population are carriers of rare groups of mtDNA. One of those groups is L3e5a that is usually found in North and Central Africa. The Icelandic L3e5a therefore possibly has African origins. The objective of this study is to determine when carriers of this haplogroup arrived in Iceland. Two hypotheses exist. The first hypothesis is that the L3e5a haplogroup arrived around 870 AD at the time of the settlement in Iceland. The second hypothesis is that the haplogroup arrived later and possibly with those who returned from the Turkish abductions in 1627. In the deCODE genetic database 74 individuals were found carrying the L3e5a haplogroup and all individuals could be traced to five matrilineal ancestors born between 1630 and 1748. Consensus sequences were made for the five ancestors and compared with 34 mtDNA sequences from literature. One sequence, from Hungary, had similarities to the Icelandic ones but the origin of that sequence is unknown. The frequency of the haplogroup in the Icelandic population was compared to other European populations, as well as few from Africa, to see whether the Icelandic frequency differed. The haplogroup has not been found in Scandinavia or the British Isles. Predicted frequencies for these areas are similar to Iceland. This suggests that the haplogroup may be found there in small numbers, and has not been found due to small sample size. In conclusion it is likely that the L3e5a haplgroup arrived with the settlement.Erfðamengi Íslendinga hefur verið mikið rannsakað. Á seinustu tveimur áratugum hefur Íslensk erfðagreining safnað lífsýnum úr meira en hálfri þjóðinni. Rannsóknir á hvatbera- og Y-litnings erfðum hafa sýnt það að Íslendingar eru að mestu ættaðir frá Skandinavíu og Bretlandi. Einnig hafa fundist framandi hvatberaerfðir, þar á meðal af hvatberahóp L3e5a sem algengast er að finna í Mið- og Norður Afríku. Möguleiki er því að þessi hvatberahópur á Íslandi sé uppruninn í Afríku. Markmið þessarar rannsóknar er að reyna tímsetja komu hvatberahópsins L3e5a til Íslands. Tvær kenningar eru til um það. Sú fyrri segir að hvatberahópurinn hafi borist til Íslands með landnámi í kringum 870. Seinni kenningin segir að hvatberahópurinn hafi komið seinna til landins og mögulega með þeim sem snéru aftur til Íslands eftir Tyrkjaránið 1627. Í gagnagrunni Íslenskrar erfðagreiningar fundusts 74 einstaklingar meðal raðgreindra sýna sem bera hvatberahópinn L3e5a og voru þeir komnir af fimm formæðrum, fæddar á árunum 1630 til 1748. Erfðaraðir voru gerðar fyrir ættleggina fimm og voru þær raðir bornar saman við 34 þekktar hvatberaraðir. Ein röð var lík þeim íslensku, frá Ungverjalandi, en uppruni þeirrar raðar er ekki þekktur. Tíðni hvatberahópsins á Íslandi var borin saman við tíðni í nokkum löndum Evrópu, sem og í Afríku, til þess að sjá hvort hún væri ólík. Hvatberahópurinn hefur hvorki fundist í Skandinavíu né á Bretlandseyjum. Spáð var fyrir um tíðni á þessum svæðum og var hún svipuð þeirri tíðni sem finnst á Íslandi. Líklega finnst hvatberahópurinn á þessum svæðum en vegna þess hve úrtakið er lítið, miðað við Ísland, þá hefur hópurinn ekki fundist þar. Út frá því er hægt að álykta að hvatberahópurinn hafi komið til Íslands með landnámi