BBS Faculty Member - Cassandra Extavour

Cassandra Extavour

Department of Organismic and Evolutionary Biology

Harvard, FAS Org. and Evol. Biology
BioLabs 4103
16 Divinity Ave
Cambridge, MA 02138
Tel: 617-496-1935
Fax: 617-496-9507
Lab Members: 2 postdoctoral fellows, 6 graduate students, 3 undergraduate students
Visit my lab page here.

My lab is interested in the evolution of early embryonic development. We are a collection of developmental biologists, molecular biologists, geneticists, cell biologists, zoologists, and evolutionary biologists. Our shared interest is in the evolution of the genetic mechanisms employed during early animal embryogenesis to specify cell fate, development and differentiation.

We focus primarily on the evolution and development of reproductive systems, including both the germ line and the somatic components of the gonad. We use molecular genetic developmental analysis, histological analysis, and experimental embryology to study early animal embryogenesis, germ cell specification, and gonad development in several different invertebrate model systems. Our laboratory models are Drosophila (fruit fly), Gryllus (cricket), Oncopeltus (milkweed bug), Parhyale (crustacean), and Achaearanea (spider). Our ultimate goal is to improve our understanding of which developmental mechanisms may have been basal to arthropods, and ultimately to metazoans, and how these mechanisms may have changed throughout evolution.

Germ cells play a unique role in gamete production, heredity and evolution. Germ cells are likely also the closest wild type in vivo equivalent to laboratory-maintained stem cells. Therefore, to understand the mechanisms that specify germ cells is a central challenge in developmental, stem cell, and evolutionary biology.

Last Update: 1/28/2014


For a complete listing of publications click here.



Green II, D.A. and Extavour, C.G. Insulin Signaling Underlies Both Plasticity and Divergence of a Reproductive Trait in Drosophila. Proceedings of the Royal Society B: Biological Sciences (in press) [PDF of accepted MS]

Ahuja, A. and
Extavour, C.G. Patterns of molecular evolution of the germ line specification gene oskar suggest that a
novel domain may contribute to functional divergence in
Drosophila. Development, Genes and Evolution (in press)[PDF of accepted MS]

Sharma, P.P., Gupta, T., Schwager, E.E., Wheeler, W., and
Extavour C.G. Subdivision of arthropod cap-n-collar expression domains is restricted to Mandibulata. EvoDevo 5(1): 3 (2014) PDF PubMed

Gupta, T. and
Extavour, C.G. Identification of a putative germ plasm in the crustacean Parhyale hawaiensis.EvoDevo 4(1): 34 (2013) PDF PubMed

Nast, A. R. and
Extavour, C.G. Ablation of a single cell from eight-cell embryos of the amphipod crustacean Parhyale hawaiensis. Journal of Visualized Experiments (in press) doi:10.3791/51073 (2014) [PDF of accepted MS]

Extavour, C.G. Live long and prosper: Germline stem cell maintenance revisited. BioEssays 35(9): 763 (2013) PDFPubMed

Ewen-Campen, B., Donoughe, S., Clarke, D.N., and
Extavour, C.G. Germ Cell Specification Requires Zygotic Mechanisms Rather Than Germ Plasm in a Basally Branching Insect. Current Biology 23(10): 835-842 (2013) PDFPubMed

Zeng, V. Ewen-Campen, B., Horch, H.W., Roth, S., Mito, T., and
Extavour, C.G. Developmental Gene Discovery in a Hemimetabolous Insect: De Novo Annotation and Assembly of a Transcriptome for the Cricket Gryllus bimaculatus.PLoS ONE 8(5): e61479 (2013) PDF PubMed

Ewen-Campen, B.*, Jones, T.E.*., and
Extavour, C.G. Evidence against a germ plasm in the milkweed bugOncopeltus fasciatus, a hemimetabolous insect. Biology Open (Company of Biologists) 2(6):556-568 (2013) (* equal author contribution) PDF PubMed

Sharma, P.P., Schwager, E.E., Giribet, G.G., Jockusch, E. and
Extavour, C.G. Distal-less and dachshund pattern both plesiomorphic and derived structures in chelicerates: RNA interference in the harvestman Phalangium opilio(Opiliones) Evolution and Development 15(4): 228-242 (2013) PDF PubMed * Cover Article *

© 2013 by the President and Fellows of Harvard College