Abstract

The origin and evolution of new genes is an active topic of research, relying on the taxonomical diversity now present in sequence databases. Using those databases, we described how oskar, a key determinant of germ cell determination, likely arose from a horizontal gene transfer and then described its evolution and conservation in insects. The number of ovarioles, the egg-producing unit of the insect ovary, is hypothesized to inform the individualʼs reproductive capacity. Using network biology approaches, we analyzed the effect of signaling pathway genes on the number of ovarioles and eggs laid by Drosophila melanogaster. We found putative gene modules regulating both traits and predicted novel genes affecting both phenotypes. The specification of germ layers is a central mechanism of the embryogenesis of animals, but the underlying molecular mechanisms have only been extensively studied in model organisms. Using Parhyale hawaiensis, a crustacean amphipod, I generated preliminary methods for the generation of single cell RNA sequencing of early embryogenesis, as well as recorded with light sheet microscopy the first three days of embryogenesis. The preliminary analyses of the sequencing datasets were inconclusive, but, analyzing one of the microscopy datasets, I described new preliminary cellular dynamic results. Finally, to observe and annotate 4D microscopy datasets, I developed a tool that allows the visualization of large volumetric datasets in Virtual Reality.

Supervisor

Cassandra G. Extavour

Program

Mollecules Cells and Organisms (MCO)

Thesis

You can download the thesis here: PhD Thesis

Location

This work was done at the Harvard University, Cambridge, MA, USA

Acknowledgments

THERE ARE TOO MANY PEOPLE TO THANK, REALLY! But I will try in this short text to do so.

First, I want to thank all the members of the Extavour laboratory. The days when going to the lab was hard, knowing that such a wonderful community of people were there always cheered me up. But more importantly, everyone taught me so much, about so many things. In particular, Seth Donoughue, thank you for always having crazy ideas and setting such a great example for me to follow. Taro Nakamura, for sharing your knowledge and always being happy to help me troubleshoot any experiment. Tarun Kumar, for being an amazing partner in science, I will always remember our collaboration fondly.

I also want to thank the members of the Harvard community whom I met and shared many adventures with. I was blessed with Ph.D. classmates who were so open-minded and kind. You helped me with science and life, and I am so grateful you were such a beautifully weird group. Thank you Finn, Sean, Georgia, Jamilla, Felix, Alyson, Katie, Yiqun, Jun Han, Linda, Nico, Matt & Sam. And I want to thank the wonderful musicians from around the world with whom I shared amazing musical moments. Harvard World Music Ensemble friends, thank you for the wonderful musical adventures we lived together. I was blessed by the chance to learn from all of you.

To all the staff that make the research endeavour at Harvard possible. Thank you Jack Conlin, Patty Gonzalez and Mike Lawrence for all your dedicated work to help the MCO community. Claire Reardon and Douglas Richardson for all the time you spent helping me with convoluted scientific apparatus. The building operation and custodial service staff for being so kind and helpful.

This adventure was also supported outside of Harvard by the members of the community I lived in during my Ph.D., the Ridgemonites. Thank you for the adventures, food, music, movies, trips, debates, discussions, and so much more. Thank you Marc, Juan, and Deborah for the time we spent together. Thank you Marc for all the knowledge of networks, physics, math, and music you gave me. Thank you Deborah for inviting me to your Philosophy groups at MIT. Thank you Juan for teaching me the ins and outs of business and life hacks.

And from as early as I can remember, thank you my family who always supporting me and accepted me as I was. My mom, Marie-Claude Larrondo who has lived the life of an academic without becoming one. Your curiosity and drive to never stop learning still lives in me. My dad, Vincent Blondel, whoʼs perseverance and love for sciences is one of the main reasons I was able to do a Ph.D. Thank you both for your unwavering love and support. My sister, Lisa Blondel, whoʼs creativity is infectious, and probably the only person I can communicate hours-long discussions without a single word being spoken. My partner, Brenda Marin Rodriguez, for the most wonderful love and support one could have ever hoped for.

I want to thank the member of my Ph.D. committee. The directions and help I received from Allon Klein, Craig Hunter and Sharad Ramanathan were instrumental in the completion of this degree. Thank you for the time you took to listen, and point me in directions I would not have conceived on my own.

And finally, I want to thank my advisor, Cassandra Extavour. When I joined your lab, I knew that it was going to be hard. You are the most rigorous person I know, and I was maybe one of the least rigorous students you had, but your patience to teach me, point my mistakes, and help me grow into a scientist is what molded me into who I am today. Thank you for always having direct conversations, never sugarcoating my mistakes. Thank you for becoming a mentor, in life and in science.