In recent years, scientists have been able to refine their molecular tools to resurrect ancient DNA from human graves and determine that yes, Yersinia pestis was the causative agent for the Black Death in the 14th century and the Plague of Justinian in the 6th century. As more and more human graves have been uncovered, their DNA has revealed many secrets that scientists even ten years ago were unable to discover. With the ability to sequence entire genomes of bacteria that died with their hosts hundreds and even thousands of years ago, researchers are exploring the rise and possible spread of Y. pestis. Each new member sequence adds to the Y. pestis family tree, pinpointing the origin of this bacteria as it diverged from its ancestor Y. pseudotuberculosis. Peering into the past, scientists have been able to track down a strain of Y. pestis from individuals in a Swedish passage grave that is basal to known strains and that the authors of a Cell article suggest has interesting implications.
This pathogenic journey into history started by analyzing ancient DNA data sets from the teeth of individuals present in a communal passage grave in Gökhem parish, located in western Sweden, for any disease-causing microbial sequences that might be present. Y. pestis was flagged in one 20-year-old female dated 4,867–5,040 years ago. The bacterial sequences from this individual, named Gok2, were more closely aligned with Y. pestis than the Y. pseudotuberculosis reference genome. Continue reading “Expanding the Plague Family Tree: Yersinia pestis in the Neolithic”
In February 2018 we wrote about a resurrection effort to bring the then endangered black-footed ferret back from the brink of extinction in western U.S. This effort was undertaken by the U.S. Fish and Wildlife Service, with assistance from Revive & Restore and partners ViaGen Pets & Equine, San Diego Zoo Global and the Association of Zoos and Aquariums. On February 18, the U.S. Fish and Wildlife Service announced announced the successful cloning of a black-footed ferret, introducing the world to a 38-day-old black-footed ferret kit “Elizabeth Ann” cloned from cells of a female ferret that died in 1988.
Cells from ferret, “Willa” were preserved by freezing, and when somatic cell nuclear transfer (SCNT) became a possibility, Willa’s cells were used to create Elizabeth Ann, the kit born just over one month ago.
Before Elizabeth Ann’s birth there were upwards of 1,000 black-footed ferrets alive in the western U.S., but they were all descendants of just 7 ferrets, and thus genetically very similar.
Analysis of Elizabeth Ann’s genome has revealed more than three times the genetic variants found in the existing wild U.S. ferrets. This means that if she is able to reproduce, her contribution to the genetic diversity of wild ferrets would be huge.
Interested in learning more about ferrets and the challenges they’ve faced in surviving and thriving in the wild? Below is our original 2018 blog with those details. Don’t miss the video clip of a young black-footed ferret doing the “weasel war dance” (below).
Writing about Yersinia pestis or the Black Death, has earned me a reputation among Promega Connections bloggers. I am interested in what researchers have been able to piece together about the causative agent of ancient plagues, what modern research shows about how Y. pestis spreads in the body and the continuing reservoirs in modern times, resulting in publication of eight blog posts on the subject. Understanding Y. pestis bacterium is of continuing interest to researchers. How did Yersinia pestis evolve from the humble Yersinia pseudotuberculosis, a pathogen that causes gastrointestinal distress, into a virulent pneumonic plague that is a global killer? One strategy for answering this question is to look at the genomic tree of Y. pestis and trace which strains had what characteristics. In a recent Nature Communications article, Zimbler et al. explored the role of the plasmid pPCP1 in Y. pestis evolution and the signature protease Pla it expresses. Continue reading “All You Need is Pla (for Pneumonic Plague)”
Sequencing Yersinia pestis, the bacterium that caused the Black Plague in Europe during 1348–50, is an amazing accomplishment. Y. pestis infection still occurs sporatically and causes fatalities despite the Age of Antibiotics. Even with animal models, there are questions remaining about the progression of infection. Nham et al. used in vivo imaging to examine the course of infection in a mouse animal model using a bioluminescent clone of Y. pestis. Continue reading “Tracking the Progression of Plague Using Bioluminescence”