17. december: Tom Gilbert – Københavns Universitet

17. december: How to understand life's origin, evolution and diversity

KU's alumneforening har bedt forskere fra Københavns Universitet om at fortælle om et af deres aktuelle forskningsprojekter. Det er tilsammen blevet til de 24 låger i årets forskningsjulekalender, hvor du kan læse om alt fra bakterier til nationale sikkerhedsstrategier.

I dagens låge fortæller professor Tom Gilbert, der er international forsker på Center for GeoGenetik om sin forskning i molekylær biologi, genetik og DNA.

Institutes like that where I am based - the Natural History Museum of Denmark - have cellars-full of long dead, dried, pickled or otherwise preserved zoological samples. Much of this material represents decades if not centuries of collecting effort, and in theory would offer a veritable treasure chest of knowledge about the animals inhabiting our planet. Over recent decades, advances in molecular biology have demonstrated just how DNA extracted from organic tissues can be used to understand life's origin, evolution and diversity, however it has become painfully clear that the quality of material needed as a base for such analyses is not found in conventional museum collections.

This challenge forms the core of my research team's interests - are most museum collections out of bounds for molecular based work, or do technical solutions exist that can open them up for study? Thanks to recent developments in so-called 'next generation' DNA and protein sequencing techniques, we are making great progress in tackling such samples, and today it seems the answer is yes - we can exploit them for use in a range of questions, spanning archaeology, anthropology, evolutionary biology and taxonomy, as some of the examples below highlight.

The extent of the Trans-Atlantic Slave Trade

Over 10million African natives were enslaved during the 18th and 19th centuries, and transported to colonial holdings in the West Indies and Americas - a role that Denmark played a considerable part in. Although the horrors of this period can never be undone, we have a responsibility to help learn as much as we can about the trade, and in this regard DNA from ancient samples can play a role. Specifically, while very accurate records exist as to where on the African coast slaves were shipped from, much less is known about where the Africans were first enslaved prior to embarkation on the slave ships - and DNA extracted from slave remains helps us place them in the context of modern African genetic diversity, thus resolving such questions.

A giant mystery

In 1857, the great Danish polymath, and employee of the forerunner to my very own institute - Japetus Steenstrup - shocked the world when he described the existence of a previously unknown gigantic squid. Know scientifically as Architeuthis dux, this beast grows to at least 12 m in length, is found globally, and yet remains largely a scientific enigma. Given the museum's long association with this beast, it is fitting that we have been leading a DNA-based global effort to better understand it, and in doing so have begun to reveal quite astounding insights into it. For example, despite its global distribution, it seems to be a single homogenous population with almost no genetic diversity - something that defies all expectations given what is known from other organisms.

Losing and finding Elephas maximus

A principal role of Natural History Museums is repositories for so-called 'type specimens' - the reference samples that act as the official representative of every species. Unfortunately, the reliability of type specimens is not always up to scratch, in particular with those that were designated in the very earliest days of scientific taxonomy. One example is the principal type specimen for Elephas maximus - otherwise known as the Asian Elephant. Through application of state-of-the-art so-called 'proteogenomics' we have demonstrated that when naming this species, Linnaeus (the father of taxonomy) made a not inconsequential error, and picked an African elephant as his example, thus invalidating its type status. As all organisms need their type, to resolve this we undertook arm-chair detective work to scourged the historical literature available on Googlebooks, and found a valid replacement, thus averting a minor taxonomic crisis.

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I morgen kan du i KU's forskningsjulekalender 2013 møde Åse Marie Hansen, der blandt andet forsker i kroppens reaktioner på stress.