Hox genes regulate asexual reproductive behavior and tissue segmentation in adult animals

Christopher P Arnold,Julianna O Haug,Frederick G Mann,Analí Migueles Lozano,Jeffrey J Lange,Chris W Seidel,Alejandro Sánchez Alvarado,Stephanie H Nowotarski

doi:10.1038/s41467-021-26986-2

Christopher P Arnold, Julianna O Haug + Show 6 more

Open Access

https://doi.org/10.1038/s41467-021-26986-2

Copy DOI

Abstract

Hox genes are highly conserved transcription factors renowned for their roles in the segmental patterning of the embryonic anterior-posterior (A/P) axis. We report functions for Hox genes in A/P tissue segmentation and transverse fission behavior underlying asexual reproduction in adult planarian flatworms, Schmidtea mediterranea. Silencing of each of the Hox family members identifies 5 Hox genes required for asexual reproduction. Among these, silencing of hox3 genes results in supernumerary fission segments, while silencing of post2b eliminates segmentation altogether. The opposing roles of hox3 and post2b in segmentation are paralleled in their respective regulation of fission behavior. Silencing of hox3 increases the frequency of fission behavior initiation while silencing of post2b eliminates fission behavior entirely. Furthermore, we identify a network of downstream effector genes mediating Hox gene functions, providing insight into their respective mechanisms of action. In particular, we resolve roles for post2b and effector genes in the functions of the marginal adhesive organ in fission behavior regulation. Collectively, our study establishes adult stage roles for Hox genes in the regulation of tissue segmentation and behavior associated with asexual reproduction.

Highlights

All data points derived from distinct single measurements of individual biological replicates
p-Values calculated with Welch's
Data points were omitted under the following conditions

Summary

Methods

CIW4 animals were sourced from a large recirculation culture and placed directly into a unidirectional flow system culture for RNAi feeding experiments[1,46]. Planarian water flows from the sump pump through a chiller, canister filter, and a UV sterilizer into the top tray. Water is able to flow back through the chiller, canister filter, and UV sterilizer back into the top tray. Cups were perforated with holes at the desired planaria water level for outflow to complete the flow vessel. These flow vessels were placed in an enclosed container on a perforated tray suspended above a collection basin and centralized waste drain.

Results

Discussion

Conclusion