Browsing by Author "Omer, Arina D."

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    Chromosome size affects sequence divergence between species through the interplay of recombination and selection
    (Wiley, 2022) Tigano, Anna; Khan, Ruqayya; Omer, Arina D.; Weisz, David; Dudchenko, Olga; Multani, Asha S.; Pathak, Sen; Behringer, Richard R.; Aiden, Erez L.; Fisher, Heidi; MacManes, Matthew D.; Center for Theoretical and Biological Physics
    The structure of the genome shapes the distribution of genetic diversity and sequence divergence. To investigate how the relationship between chromosome size and recombination rate affects sequence divergence between species, we combined empirical analyses and evolutionary simulations. We estimated pairwise sequence divergence among 15 species from three different mammalian clades—Peromyscus rodents, Mus mice, and great apes—from chromosome-level genome assemblies. We found a strong significant negative correlation between chromosome size and sequence divergence in all species comparisons within the Peromyscus and great apes clades but not the Mus clade, suggesting that the dramatic chromosomal rearrangements among Mus species may have masked the ancestral genomic landscape of divergence in many comparisons. Our evolutionary simulations showed that the main factor determining differences in divergence among chromosomes of different sizes is the interplay of recombination rate and selection, with greater variation in larger populations than in smaller ones. In ancestral populations, shorter chromosomes harbor greater nucleotide diversity. As ancestral populations diverge, diversity present at the onset of the split contributes to greater sequence divergence in shorter chromosomes among daughter species. The combination of empirical data and evolutionary simulations revealed that chromosomal rearrangements, demography, and divergence times may also affect the relationship between chromosome size and divergence, thus deepening our understanding of the role of genome structure in the evolution of species divergence.
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    Emx2 underlies the development and evolution of marsupial gliding membranes
    (Springer Nature, 2024) Moreno, Jorge A.; Dudchenko, Olga; Feigin, Charles Y.; Mereby, Sarah A.; Chen, Zhuoxin; Ramos, Raul; Almet, Axel A.; Sen, Harsha; Brack, Benjamin J.; Johnson, Matthew R.; Li, Sha; Wang, Wei; Gaska, Jenna M.; Ploss, Alexander; Weisz, David; Omer, Arina D.; Yao, Weijie; Colaric, Zane; Kaur, Parwinder; Leger, Judy St; Nie, Qing; Mena, Alexandria; Flanagan, Joseph P.; Keller, Greta; Sanger, Thomas; Ostrow, Bruce; Plikus, Maksim V.; Kvon, Evgeny Z.; Aiden, Erez Lieberman; Mallarino, Ricardo; Center for Theoretical Biological Physics
    Phenotypic variation among species is a product of evolutionary changes to developmental programs1,2. However, how these changes generate novel morphological traits remains largely unclear. Here we studied the genomic and developmental basis of the mammalian gliding membrane, or patagium—an adaptative trait that has repeatedly evolved in different lineages, including in closely related marsupial species. Through comparative genomic analysis of 15 marsupial genomes, both from gliding and non-gliding species, we find that the Emx2 locus experienced lineage-specific patterns of accelerated cis-regulatory evolution in gliding species. By combining epigenomics, transcriptomics and in-pouch marsupial transgenics, we show that Emx2 is a critical upstream regulator of patagium development. Moreover, we identify different cis-regulatory elements that may be responsible for driving increased Emx2 expression levels in gliding species. Lastly, using mouse functional experiments, we find evidence that Emx2 expression patterns in gliders may have been modified from a pre-existing program found in all mammals. Together, our results suggest that patagia repeatedly originated through a process of convergent genomic evolution, whereby regulation of Emx2 was altered by distinct cis-regulatory elements in independently evolved species. Thus, different regulatory elements targeting the same key developmental gene may constitute an effective strategy by which natural selection has harnessed regulatory evolution in marsupial genomes to generate phenotypic novelty.
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    Three-dimensional genome architecture persists in a 52,000-year-old woolly mammoth skin sample
    (Elsevier, 2024) Sandoval-Velasco, Marcela; Dudchenko, Olga; Rodríguez, Juan Antonio; Pérez Estrada, Cynthia; Dehasque, Marianne; Fontsere, Claudia; Mak, Sarah S. T.; Khan, Ruqayya; Contessoto, Vinícius G.; Oliveira Junior, Antonio B.; Kalluchi, Achyuth; Zubillaga Herrera, Bernardo J.; Jeong, Jiyun; Roy, Renata P.; Christopher, Ishawnia; Weisz, David; Omer, Arina D.; Batra, Sanjit S.; Shamim, Muhammad S.; Durand, Neva C.; O’Connell, Brendan; Roca, Alfred L.; Plikus, Maksim V.; Kusliy, Mariya A.; Romanenko, Svetlana A.; Lemskaya, Natalya A.; Serdyukova, Natalya A.; Modina, Svetlana A.; Perelman, Polina L.; Kizilova, Elena A.; Baiborodin, Sergei I.; Rubtsov, Nikolai B.; Machol, Gur; Rath, Krisha; Mahajan, Ragini; Kaur, Parwinder; Gnirke, Andreas; Garcia-Treviño, Isabel; Coke, Rob; Flanagan, Joseph P.; Pletch, Kelcie; Ruiz-Herrera, Aurora; Plotnikov, Valerii; Pavlov, Innokentiy S.; Pavlova, Naryya I.; Protopopov, Albert V.; Di Pierro, Michele; Graphodatsky, Alexander S.; Lander, Eric S.; Rowley, M. Jordan; Wolynes, Peter G.; Onuchic, José N.; Dalén, Love; Marti-Renom, Marc A.; Gilbert, M. Thomas P.; Aiden, Erez Lieberman; Center for Theoretical Biological Physics
    Analyses of ancient DNA typically involve sequencing the surviving short oligonucleotides and aligning to genome assemblies from related, modern species. Here, we report that skin from a female woolly mammoth (†Mammuthus primigenius) that died 52,000 years ago retained its ancient genome architecture. We use PaleoHi-C to map chromatin contacts and assemble its genome, yielding 28 chromosome-length scaffolds. Chromosome territories, compartments, loops, Barr bodies, and inactive X chromosome (Xi) superdomains persist. The active and inactive genome compartments in mammoth skin more closely resemble Asian elephant skin than other elephant tissues. Our analyses uncover new biology. Differences in compartmentalization reveal genes whose transcription was potentially altered in mammoths vs. elephants. Mammoth Xi has a tetradic architecture, not bipartite like human and mouse. We hypothesize that, shortly after this mammoth’s death, the sample spontaneously freeze-dried in the Siberian cold, leading to a glass transition that preserved subfossils of ancient chromosomes at nanometer scale.
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    Topologically Associated Domains Delineate Susceptibility to Somatic Hypermutation
    (Elsevier, 2019) Senigl, Filip; Maman, Yaakov; Dinesh, Ravi K.; Alinikula, Jukka; Seth, Rashu B.; Pecnova, Lubomira; Omer, Arina D.; Rao, Suhas S. P.; Weisz, David; Buerstedde, Jean-Marie; Aiden, Erez Lieberman; Casellas, Rafael; Hejnar, Jiri; Schatz, David G.; Center for Theoretical Biological Physics
    Somatic hypermutation (SHM) introduces point mutations into immunoglobulin (Ig) genes but also causes mutations in other parts of the genome. We have used lentiviral SHM reporter vectors to identify regions of the genome that are susceptible (“hot”) and resistant (“cold”) to SHM, revealing that SHM susceptibility and resistance are often properties of entire topologically associated domains (TADs). Comparison of hot and cold TADs reveals that while levels of transcription are equivalent, hot TADs are enriched for the cohesin loader NIPBL, super-enhancers, markers of paused/stalled RNA polymerase 2, and multiple important B cell transcription factors. We demonstrate that at least some hot TADs contain enhancers that possess SHM targeting activity and that insertion of a strong Ig SHM-targeting element into a cold TAD renders it hot. Our findings lead to a model for SHM susceptibility involving the cooperative action of cis-acting SHM targeting elements and the dynamic and architectural properties of TADs.