Ching-Ho Chang is the 2021 recipient of the prestigious Larry Sandler Award (https://genestogenomes.org/ching-ho-chang-to-give-larry-sandler-memorial-lecture-at-dros21/). This award honors Dr. Larry Sandler for his many important contributions to Drosophila genetics, including his foundational work on meiotic drive. The award is given to an outstanding recent doctoral graduate working on Drosophila genetics, based their thesis. Ching-Ho’s thesis focused on how genetic conflicts, and especially meiotic drive, shape chromosome evolution in Drosophila. As the award winner, Ching-Ho delivered the Larry Sandler Memorial Lecture at the 2021 annual Drosophila research conference. We are so proud of Ching-Ho!!
Team supergene! Postdoc John Sproul (top left), undergraduate and team captain Sherif Negm (top right), grad student Xiaolu Wei (bottom left), and postdoc Lucas Hemmer (bottom right)
Xiaolu Wei is a recipient of an Agnes M. Messersmith and George Messersmith Dissertation Fellowship – a highly competitive fellowship that recognizes promising University of Rochester PhD candidates. This fellowship will support Xiaolu’s dissertation work on satellite DNA regulation and Segregation Distorter in 2020-2021. Congratulations Xiaolu!
Ching-Ho successfully defended his dissertation on “Meiotic drive and rapid genome evolution in Drosophila”. He will start his postdoctoral work at the Fred Hutchison Cancer Research Center this April. We’ll miss you greatly Dr. Chang!
Congratulations to the first PhD graduate from the Larracuente lab: Danielle Khost! She’s off to a fantastic bioinformatics position in the Harvard Bioinformatics group. We’ll miss her dearly.
Check out our new paper on the organization of Drosophila melanogaster centromeres. For this paper, our lab collaborated with Barbara Mellone’s lab (University of Connecticut) and Ting Wu’s lab (Harvard University) to discover all of the centromeres in D. melanogaster. Centromeres are genomic regions essential for proper chromosome segregation during cell division. They also are among the most rapidly evolving regions of genomes and can play a role in karyotype evolution and speciation. We know little about the detailed organization of centromeres because they are buried in large blocks of tandem repeats that are difficult to assemble. We combined Ching-Ho’s heterochromatin-enriched assembly methods, with ChIP-seq for the centromere-specific histone variant, CENP-A, and FISH on stretched chromatin fibers to reveal the DNA sequences underlying centromeres. It turns out that centromeres correspond to islands rich in retroelements embedded in a sea of satellite DNA! One retroelement, G2/Jockey-3, is found at all D. melanogaster centromeres and centromeres in D. simulans.
Retroelements are associated with centromeres in a wide range of organisms including fungi, plants, and mammals. This suggests that retroelements may be conserved features of centromeres and may have a role in centromere function. We’re currently working on studying patterns of polymorphism and divergence in G2/Jockey-3 and centromere islands to see how they contribute to centromere evolution and function.
Drosophila centromere organization and widespread presence of retroelements at centromeres. Figure 7 from the centromere paper. (A) Schematic showing the organization of D. melanogaster centromeres. (B) Phylogenetic tree showing that centromere-associated retroelements are common across highly diverged lineages: Gossypium hirsutum (cotton), Zea mays mays (maize), Oryza sativa (rice), Triticum boeoticum (wild wheat), Cryptococcus, Phyllostomid (bat), Hoolock leuconedys (gibbon), Homo sapiens (human) (and a human neocentromere), Macropus eugenii (tammar wallaby), Phascolarctos cinereus (koala), and D. melanogaster (this study for endogenous centromeres; also in an X-derived minichromosome).
Taylar successfully defended her senior thesis on suppressors of Segregation Distorter in Drosophila melanogaster and is graduating with honors in research this weekend! Next up for Taylar is the Cell, Development, Molecular Biology and Biophysics PhD program Johns Hopkins, where she will be a Morgan Fellow. Congratulations all around Taylar!
Ching-Ho was awarded a Government Scholarship to Study Abroad from the Taiwan government. He’ll use these funds to study the evolution of a new multi-copy Y-linked gene family specific to the Drosophila simulans clade. Congratulations Ching-Ho!!
