Biology subjects

Poon, H.

Publications and source records attributed to Poon, H..

2 recordsLinked to original sources

bioRxiv2025

Maternal Effects on Postembryonic Neuroblast Migration in C. elegans

Maternal effect genes mostly regulate early embryogenesis as their mRNAs or proteins are deposited into the oocytes to function during early embryonic development before the onset of zygotic transcription. Here, we report a case where a maternal effect gene regulates postembryonic neuroblast migration long after the early embryonic stages. We found that the defects of the Q neuroblast migration in C. elegans mannosyltransferase dpy-19 mutants can be rescued by a maternal copy of the gene. Maternal dpy-19 mRNAs are deposited into the oocytes and persist throughout embryonic development into the Q cells to regulate their migration in early larval stages. These mRNAs appeared to be remarkably stable, since long-term developmental arrest, changing the 3UTR sequence, and mutations in genes involved in RNA binding and modification all had weak effects on the maternal rescue of the neuroblast migration defects. Since the defects can also be rescued by a zygotic copy of dpy-19(+), our results suggest that postembryonic neurodevelopment is redundantly regulated by maternal and zygotic copies of the same gene.

developmental biology↗

bioRxiv2025

Functional Interrogation of Neuronal Subtypes via Intersectional Expression of Optogenetic Actuator Reveals Non-linear Components in a Linear Circuit

Investigating signal integration in a neural circuit is oftentimes challenging when the circuit contains neuronal subtypes that are transcriptomically similar, due to the lack of tools to express optogenetic actuators with high cellular specificity and to deliver light with high spatiotemporal accuracy. Here, we demonstrate the use of a split GAL4-based genetic "AND" gate to express Chrimson in specific touch receptor neuron (TRN) subtypes in the C. elegans touch response circuit. Combining this intersectional strategy for transgene expression with high-throughput optical targeting and behavioral quantification, we optogenetically interrogated the role of each TRN subtype in mediating the mechanosensor-induced escape response and in integrating signals that trigger the opposite motor output. Surprisingly, we found that although the response of the overall circuit linearly combines the competing anterior and posterior stimuli, this linearity is comprised of antagonistic non-linear contributions from the anterior and posterior sensors, which conspire to generate a linear response.

neuroscience↗