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Home / Science / Gene transcripts of ancient wolves that were analyzed after 14,000 years in permafrost

Gene transcripts of ancient wolves that were analyzed after 14,000 years in permafrost



<div data-thumb = "https://3c1703fe8d.site.internapcdn.net/newman/csz/news/tmb/2019/5d40a10e1c503.jpg" data-src = "https: //3c1703fe8d.site.internapcdn .net / newman / gfx / news / hires / 2019 / 5d40a10e1c503.jpg "data-sub-html =" Fig. 1: Regression of old liver and historical skin samples, Method 1: Relationships between 95th percentile of expressed genes in each control tissue sample (x-axis) and any old sample or control sample from other tissues (y-axis) Black points in charts comparing old samples are the relationships between the control tissue and the corresponding old tissue control tissue and other old tissues, subtitled in the Yellow lines are linear least-squares regression for black points Green lines are linear least-squares regression for red points Filled lines indicate significant linear regression Dotted lines show insignificant linear regression regression. (A) BGISEQ-500 data, d E-duplicated; (B) HiSeq 2500 data, de-duplicated; (C) BGISEQ-500 data, duplicates kept; (D) HiSeq 2500 data, duplicates are retained. The underlying data for this number comes from the Varistran output, which is summarized in S2 data and S3 data. Picture credits: PLOS Biology (201
9). DOI: 10.1371 / journal.pbio.3000166 ">

<img src = "https://3c1703fe8d.site.internapcdn.net/newman/csz/news/800/2019/5d40a10e1c503.jpg" alt = "Gene transcripts of the old wolf analyzed in permafrost after 14,000 years" title = "Fig. 1 Regression of Antique Liver and Historical Skin Samples, Method 1: Relationships between the 95th percentile of the expressed genes in each control tissue sample (x-axis) and each antique sample or control sample from other tissues (y-axis) diagrams comparing previous samples Superimposed red dots represent the relationship between the control fabric and other old fabrics indicated in the subtitle of the diagram. Yellow lines are linear least squares corrections that are suitable for black dots Lines are linear least squares corrections adapted to red points, and filled lines represent significant linear regression. Dashed L inien represent a non-significant linear regression. (A) BGISEQ-500 data, de-duplicated; (B) HiSeq 2500 data, duplicated duplicate; (C) BGISEQ-500 data, duplicates kept; (D) HiSeq 2500 data, duplicates are retained. The underlying data for this number comes from the Varistran output, which is summarized in S2 data and S3 data. Picture credits: PLOS Biology (2019). DOI: 10.1371 / journal.pbio.3000166 "/>
Figure 1: Regression of Antique Liver and Historical Skin Samples, Method 1: Relationships between the 95th percentile of the expressed genes in each control tissue sample (x-axis) and each antique or control sample from other tissues (y-axis). Black dots in charts comparing old samples are the relationships between the control tissue and the corresponding old tissue. Superimposed red dots indicate the relationship between the control tissue and other old tissues indicated in the subtitle of the graph. Yellow lines are linear least squares corrections that are suitable for black dots. Green lines are linear least squares corrections that are suitable for red dots. Filled lines indicate a significant linear regression. Dashed lines indicate a non-significant linear regression. (A) BGISEQ-500 data, de-duplicated; (B) HiSeq 2500 data, de-duplicated; (C) BGISEQ-500 data, duplicates kept; (D) HiSeq 2500 data, duplicates are retained. The underlying data for this number comes from the Varistran output, which is summarized in S2 data and S3 data. Picture credits: PLOS Biology (2019). DOI: 10.1371 / journal.pbio.3000166

RNA – the short-lived transcripts of genes – from the "Pomeranian wolf" tumor pup, was isolated and its sequence analyzed in a new study by Oliver Smith of the University of Copenhagen and colleagues who have published on 30 July in the Open Access Journal PLOS Biology . The results support the possibility of studying a range of RNA transcripts from ancient organisms, an option previously considered highly unlikely due to the short lifetime of RNA.

It is known that DNA encoding the "hard copy" of genes survives thousands of years under favorable conditions. But RNA – the short-lived working copy of a gene that is transcribed by the DNA in the cell and provides the instructions for the production of proteins – is rapidly degraded in living tissue by a series of recycling enzymes. This instability typically persists after death, and for this reason, researchers have generally believed that the likelihood of finding the RNA complement of an old cell – its transcriptome – intact was negligible. However, there were a few exceptions, especially in plants, which led the authors to question whether there might be ancient animal transcriptomes that are well-preserved for sequencing.

They isolated and analyzed RNA from liver tissue from a 14,300-year-old old canid, possibly a wolf or a partially domesticated wolf-like creature that had been preserved in Siberian permafrost until its discovery, as well as tissue from two 19th-century wolves. and 20th century. Using a variety of transcriptomic techniques and quality control measures, the team demonstrated that the RNA sequenced from the Pleistocene Canid is truly representative of the animal's RNA, with many liver-specific transcripts that fit more modern samples of wolves and dogs. [19659004] The transcriptome of the Siberian canid is the oldest RNA sequenced by far and surpasses the next oldest transcriptome by at least 13,000 years. The authors state that unlike paleo-genomics, palaeo-transcriptomics is unlikely to become routine, since even under the best conditions, RNA is not as well conserved as DNA.

However, there are likely to be a large number of other natural phenomena. Frozen samples that allow for the decryption of the transcriptome not only open researchers to the genes of ancient organisms, but also to the flow of transcriptome-encoded cell activity.

"Ancient DNA researchers were previously reluctant to attempt sequencing of ancient RNA because it is generally more unstable than DNA and more susceptible to enzymatic degradation," Dr. Smith. "However, after our recent successes in sequencing ancient RNA from plant material, we speculated that a well-preserved animal specimen frozen in permafrost may contain enough sequencing material, and we were pleased to not only find what we found RNA from different tissues, but in some cases the signal was so strong that we could make biologically meaningful distinction between tissues.

it might be tempting to ask, "well and?". However, we believe For example, many of the most clinically relevant viruses today have RNA genomes, and the RNA stage is often crucial for understanding the intricacies and complexities of gene regulation, which could impact on the discussion of environmental pressures that drive evolution. "


Perfectly preserved wolf-head from the Ice Age, found in Siberia


Further information:
Oliver Smith et al., Ancient Permafrost RNA from the Late Pleistocene and Historic Canids, show the tissue-specific survival of the transcriptome, PLOS Biology (2019). DOI: 10.1371 / journal.pbio.3000166

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Gene transcripts of the old wolf analyzed after 14,000 years in permafrost (2019, July 30)
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