Abstract:
The complex of Mon1-Ccz1 functions as a GEF (Guanosine nucleoside exchange factor)
for Rab7 and mediates the transition of Rab5 marked early endosomes to late
endosomes. Drosophila Mon1 mutants have a shortened lifespan, have motor defects and
are sterile. The egg chambers fail to mature resulting in stalling of oocytes at the
previtellogenic stages. These defects can be rescued by expression of Dmon1 in the
octopaminergic/tyraminergic neurons (DHIMAN et al. 2019). Eggs laid by neuronallyrescued
Dmon1lof mutants fail to hatch into larvae indicating maternal roles for Dmon1.
The cuticle pattern of these embryos shows absence of head structures and suggests a
possible failure in axial patterning. We probed these embryos for spatiotemporal
expression of A-P and D-V patterning genes using RNA in-situ hybridization. While D-V
patterning genes, namely twist, snail, short-gastrulation and decapentaplegic show near normal patterns of expression, the A-P patterning genes nanos and oskar are mislocalised. This
indicates that Dmon1 has a critical role in localising the determinants of the A/P axis in
the egg. We hypothesize that this role may be related to Mon1’s function as a Rab
converter.
