Mark Rebeiz

Really excited for PASEDB2025 in July!

🐟 I’ve been herring all about it!
Fish satellite symposia speaker talks at #PASEDB

Invited speaker: @fishevodevogeno.bsky.social

Organizers: @nakamuralab.bsky.social @patyschneider22.bsky.social & Joaquín Letelier

Register: evodevo.wildapricot.org/event-6007396

🌟Remember to register #PASEDB 2025 Biennial Meeting (July 22-25)!

We have an incredible line up of activities and speakers, including 4 satellite symposia (July 22): Spiralia🐌, Arthropods🦋, Fishes🐟 and Non-bilaterian 🪸

Register and submit today!
evodevo.wildapricot.org/event-6007396

🌟We have great satellite meetings!🥳😎

- Spiralia 🐌🪱
- Arthropods 🦋🦗🪰🪳
- Fishes🐠🐟🐡
- Non-bilaterian 🪼🪸

Remember to register here: evodevo.wildapricot.org/event-6007396

#evodevo #pasedb #science

Thanks so much Amber! Hope you are having an awesome time in your postdoc!

BTW our bad - Gavin's handle is @gavinrrice.bsky.social

Thank you to the O'Connor-Giles lab for updating the incredible CRISPR Optimal Target Finder to include D. eugracilis. @bdsc.bsky.social for lines, and @flybase.bsky.social for being our favorite database

We want to thank our amazing collaborators Julia Zeitlinger and Tatiana Gaitan. We cannot wait to share more as we continue to dive deeper into how the trichome genetic network has specialized!

Schematic representation of the origin and specialization of the D. eugracilis aedaegal sheath trichomes and its genetic network

Our results demonstrate the power of genetic network co-option to redeploy a genetic network into a new tissue context. Yet, novelties are more than mere iterations of repeated structures. We reflect on how they derive unique features by elaborating their network architecture.

induction of ectopic trichomes in D. melanogaster by mis-expressing shavenbaby.

Misexpression of the active form of shavenbaby in the naïve aedeagal sheath of D. melanogaster was sufficient to induce small trichomes.
This is one of the first times that genetic network co-option has been recapitulated through experimental manipulations.

adult aedaegal sheaths of D. eugracilis control and shavenbaby CRISPR treatments which reduced height of the largest trichomes.

Disruption of shavenbaby via mosaic CRISPR caused the truncation of trichome height, showing the important role of shavenbaby, but also indicating that there are likely other redundant transcription factors as well

shavenbaby GRN showing multiple downstream functions (ECM, actin and "other".

Additionally, we find that the trichome genetic network was partially co-opted into the aedeagal sheath as 14 (purple) out of 23 direct targets of shavenbaby we tested have gained expression in the D. eugracilis aedeagal sheath

expression of shavenbaby protein (top) and mRNA (bottom) in D. melanogaster (no expression in the sheath) and D. eugracilis (expression in the sheath - outlined)

The novel unicellular outgrowths of D. eugracilis have evolved expression of the key trichome transcription factor shavenbaby, named for its mutant phenotype, in which trichome morphology is disrupted

We found that each of these outgrowths develop as an actin-rich (magenta) extension of a single cell (apical cell junctions grey), similar to trichomes, hair-like structures that cover the larvae and much of the adult cuticle

The adult aedeagal sheaths of D. pseudoobscura, D. ananassae, D. melanogaster, and D. eugracilis (which is the only species with a variety of differently sized outgrowths).

We developed the rapidly evolving drosophilid terminalia as a model to explore the genetic basis of novelty. D. eugracilis has over 150 differently sized outgrowths on its aedeagal sheath which appear to be absent from other species of Drosophila, including D. melanogaster.

3D micrograph of the developing D. eugracilis terminalia

Our new @CurrentBiology paper provides a rare glimpse into a morphological novelty in Drosophila eugracilis
In it, @gavinrrice and colleagues, infer and reproduce the likely initial steps of a novelty's formation
www.sciencedirect.com/science/arti...