Dr. Octavio M. Palacios-Gimenez

My research focuses on the study of genome evolution in the grasshopper Vandiemenella viatica species complex, particularly sex chromosomes and repetitive DNA using comparative genomics, molecular biology and cytogenetics. While most of the viatica species have X0 system, where females have two X chromosomes and males only one, there has been repeated and independent chromosomal fusions between the ancestral X0 races and autosomes resulting in the formation of new Y chromosomes (males neo-XY and females neo-XX). This allows independent comparisons between pairs of races with different combinations of autosome-X chromosome fusions to investigate the timing and patterns of recombination suppression, gene loss, gene expression differentiation, and genome divergence.

Sex is a fundamental and ancient feature of eukaryotic reproduction often associated with the presence of specialized sex chromosomes involved in female or male development. Despite the importance and conservation of sexual reproduction, there is a notable diversity of sex chromosomes within and between sexes: XY system with female XX and male XY, and ZW system with female ZW and male ZZ. This diversity is likely to have key consequences for multiple facets of evolution, as sex chromosomes play central roles in adaptation, speciation and sexual dimorphism but remains unclear how sex chromosomes are built and what kind of sex-specific changes occur. Understanding the causes and consequences of sex chromosome evolution requires study systems where sex chromosomes have evolved recently and independently several times. My current research involve the understanding of the early signatures of sex chromosome evolution using the grasshopper Vandiemenella viatica species complex. While most species have and X0 system, where females have two X chromosomes and males only one, there has been repeated and independent chromosomal fusions between the ancestral X and autosomes resulting in the formation of new Y chromosomes. By combining state-of-the art genomics, transcriptomics, single cell resolution, and cytogenetics, we seek to provide an integrated understanding of the early signatures of sex chromosome evolution. The research aims to answer three key questions:

1. How is recombination suppressed between nascent sex chromosomes?
2. How does gene regulation evolve after recombination suppression?
3. How fast does the neo-Y degenerate after recombination suppression?

Cabral-de-Mello, D.C. & Palacios-Gimenez, O.M. (2024). Repetitive DNAs: The “invisible” regulators of insect adaptation and speciation. Current Opinion in Insect Science doi: 10.1016/j.cois.2024.101295External link 

Jayaprasad, S., Peona, V., Ellerstrand, S.J., Rossini, R., Bunikis, I., Pettersson, O.V., Olsen, R.-A., Rubin, C.-J., Einarsdottir, E., Bonath, F., Bradford, T.M., Cooper, S.J.B., Hansson, B., Suh, A., Kawakami, T., Schielzeth, H. & Palacios-Gimenez, O.M. (2024). Orthopteran neo-sex chromosomes reveal dynamics of recombination suppression and evolution of supergenes. Molecular Ecology doi: 10.1111/mec.17567External link 

Li, X., Jayaprasad, S., Einarsdottir, E., Cooper, S.J.B., Suh, A., Kawakami, T. & Palacios-Gimenez, O.M. (2024). Chromosome-level genome assembly of the morabine grasshopper 
19. Scientific Data 11: 997. doi: 10.1038/s41597-024-03858-0External link

Peona, V., Palacios-Gimenez, O.M., Lutgen, D., Olsen, R.A., Alaei Kakhki, N., Andriopoulos, P., Bontzorlos, V., Schweizer, M., Suh, A. & Burri, R. (2023). An annotated chromosome-scale reference genome for Eastern black-eared wheatear (Oenanthe melanoleuca). G3 - Genes Genomes Genetics doi: 10.1093/g3journal/jkad088External link 

Castillo, E., Cabral-de-Mello, D.C., Martí, D.A., Scattolini, M., Palacios-Gimenez, O.M. & Cigliano, M. (2023). Karyotype evolution in Ronderosia grasshoppers (Orthoptera, Acrididae). Zoological Journal of the Linnean Society doi: 10.1093/zoolinnean/zlac090External link 

Peona, V., Palacios-Gimenez, O.M., Blommaert, J., Liu, J., Haryoko, T., Jønsson, K.A., Irestedt, M., Zhou, Q., Jern, P. & Suh, A. (2021). The avian W chromosome is a refugium for endogenous retroviruses with likely effects on female-biased mutational load and genetic incompatibilities. Philosophical Transactions of the Royal Society B 376: 20200186. doi: 10.1098/rstb.2020.0186External link

Martí, E., Milani, D., Bardella, V.B., Albuquerque, L., Song, H., Palacios-Gimenez, O.M. & Cabral-de-Mello, D.C. (2021). Cytogenomic analysis unveils mixed molecular evolution and recurrent chromosome rearrangements shaping the multigene families on Schistocerca grasshopper genomes. Evolution doi: 10.1111/evo.14287External link

Mahadevaraju, S., Fear, J.M., Akeju, M., Galletta, B.J., Pinheiro, M.M.L.S., Avelino, C.C., Cabral-de-Mello, D.C., Conlon, K., Dell’Orso, S., Demere, Z., Mansuria, K., Mendonça, C.A., Palacios-Gimenez, O.M., Ross, E., Savery, M., Yu, K., Smith, H.E., Sartorelli, V., Yang, H., Rusan, N.M., Vibranovski, M.D., Matunis, E. & Oliver, B. (2021). Dynamic sex chromosome expression in Drosophila male germ cells. Nature Communications 12: 892. doi: 10.1038/s41467-021-20897-yExternal link

Santander, M.D., Cabral-de-Mello, D.C., Taffarel, A., Martí, D.A., Palacios-Gimenez, O.M. & Castollo, E.R.D. (2021). New insights into the six decades of Mesa’s hypothesis of chromosomal evolution in Ommexechinae grasshoppers (Orthoptera: Acridoidea). Zoological Journal of the Linnean Society 20: 1-15. doi: 10.1093/zoolinnean/zlaa188/6138200External link

Ferretti, A.B.S.M., Milani, D., Palacios-Gimenez, O.M., Ruiz-Ruano, F.J. & Cabral-de-Mello, D.C. (2020). High dynamism for neo-sex chromosomes: satellite DNAs reveal complex evolution in a grasshopper. Heredity 125: 124-137. doi: 10.1038/s41437-020-0327-7External link

Palacios-Gimenez, O.M., Koelman, J., Palmada-Flores, M., Bradford, T.M., Jones, K.K., Cooper, S.J.B., Kawakami, T. & Suh, A. (2020). Comparative analysis of morabine grasshopper genomes reveals highly abundant transposable elements and rapidly proliferating satellite DNA repeats. BMC Biology 18: 199. doi: 10.1186/s12915-020-00925-xExternal link

Palacios-Gimenez, O.M., Milani, D., Song, H., Marti, D.A., Lopez-Leon, M.D., Ruiz-Ruano, F.J., Camacho, J.P.M. & Cabral-de-Mello, D.C. (2020). Eight million years of satellite DNA evolution in grasshoppers of the genus Schistocerca illuminate the ins and outs of the library hypothesis. Genome Biology and Evolution 12: 88-102. doi: 10.1093/gbe/evaa018External link