Culotta, 2015 (new life for old bones) Flashcards
A … year old thighbone from … was used to sequence the oldest genome of our species
45,000, Siberia
The oldest animal genome sequenced so far has been a … year old ….
700,000 horse
Sequencing and sample preparation technologies have improved and can now be used to extract far more information from ancient fossils than they previously could. Ancient DNA extraction tools are now much more widely available.
woop woop
After the first ancient DNA successes in the …, the field struggled with …, as the genetic material from modern or ancient … or even the scientists themselves could be falsely identified as ancient DNA from the sample.
1980s, contamination, bacteria
Originally, researchers used the … to amplify and sequence the DNA fragments that survive from ancient samples. What was the problem with this?
PCR (polymerase chain reaction)
PCR preferentially amplifies longer molecules, which are more likely to be modern contaminants
Today, with modern developments in technology, researchers can sequence millions of DNA fragments at once and sometimes produce a full genome within a day, for much lower costs.
These new, “next-gen” sequencers do not rely on … to reconstruct molecules and can recognise sequences likely to be from …, so these can be ….
PCR, contaminants, discarded
+ new preparation techniques allow useful information to be extracted from fossil DNA of limited quality
Due to all this, the ancient genomes of … humans and other ancestors (e.g. …) can be sequenced to a quality similar to that of present-day people
archaic, neanderthals
The tally of published papers with ancient DNA rose from … in 1995 to … in 2014
30, 275
Researchers are identifying new places to find well-preserved ancient DNA sequences, for example the dense … bone of the ear and the … on teeth have been found to preserve DNA well.
petrosal, plaque (which can also be used to infer ancient diet and microbiome)
Some researchers are using DNA sequenced from ancient … and … to reconstruct past ecosystems
soil, ice
Singh (2013) sequenced five medieval samples of Mycobacterium … (leprosy) and showed that its genome has essentially remained the same since medieval times. So it has not evolved to become less …, and perhaps infects less people in Europe these days due to reduced … with other diseases or the evolution of a protective … in humans.
leprae, virulent, coinfection, mutation
One team has challenged themselves to sequence the genomes of … individuals that are least … years old, calling this the “… … … project”
- the fragmented DNA of such old specimens often must be sequenced up to … times, at $2000 per copy, in order to be reliable
100, 30,000, 100 archaic genomes, 40
“next generation sequencing doesn’t remove the issues of …” - Alan Cooper from Uni of Adelaide, Australia
- who fears mistakes will become common again as more labs try their hand
contamination
