Submission Date

7-19-2019

Document Type

Paper- Restricted to Campus Access

Department

Biology

Faculty Mentor

Rebecca Lyczak

Comments

Presented during the 21st Annual Summer Fellows Symposium, July 19, 2019 at Ursinus College.

This project was supported by a National Institutes of Health Academic Research Enhancement Award (AREA) grant (1 R15 GM110614-02).

Project Description

The puromycin-sensitive aminopeptidase, PAM-1, is crucial for polarity establishment, pseudocleavage, and symmetric division, all of which are clear signs of viable development of one cell C. elegans embryos. We have found restorative effects of these phenotypes in pam-1 worms by adding secondary suppressor mutation wee-1.3 (lz5). WEE-1.3 is an inhibitory kinase that regulates maturation promoting factor (MPF) to control the timing of oocytes entering M phase during interphase of mitosis. This allows oocytes to mature at a controlled rate before fertilization and meiosis occur. To test for further interactions between PAM-1 and WEE-1.3, we looked at how the absence of WEE-1.3 in wildtype and pam-1 worms affected oocyte maturation. Wildtype worms that were grown on wee-1.3 RNA interference (RNAi) plates became sterile. This is due to oocytes maturing precociously and trying to undergo meiosis before fertilization, which we were able to visualize by counting nucleoli. Nucleoli are strong indicators of oocyte maturity, so the absence of nucleoli indicated rapid maturation. However, pam-1 worms that were grown on wee-1.3 RNAi plates were not sterile and their nucleoli counts seemed to be rescued back to what we would expect to see in wildtype worms. For these reasons, we suspect that pam-1 and wee-1.3 interact during oocyte maturation in addition to early embryogenesis. We used meiotic exit timing, the time between the extrusion of the second polar body and the formation of the pronucleus, to see if pam-1 could rescue early meiosis in wee-1.3 mutants.

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