Females carrying two copies of thr^{ΔVQ.T:Hsap\MYC} are fertile at 25^oC, but almost completely sterile at 18^oC. At 18^oC, many eggs are laid but very few larvae hatch. The cold sensitive period occurs during the early stages of embryogenesis; embryos maintained at 25^oC for the first 3.5 hours of development and then raised at 18^oC hatch. 35% of syncytial embryos derived from females carrying two copies of thr^{ΔVQ.T:Hsap\MYC} and raised at 18^oC during early development have various irregularities, which include embryonic regions with mitotic asynchrony, abnormal mitotic figures and lower nuclear densities than normal. Many embryos with regular nuclear distribution have fewer nuclei compared to control embryos of the same age. During cellularisation 99% of embryos derived from females carrying two copies of thr^{ΔVQ.T:Hsap\MYC} and raised at 18^oC during early development lose a large fraction of nuclei from the egg periphery (the nuclei accumulate in the yolk region in the interior of the egg). Cellularisation is delayed in these embryos compared with nuclear elongation. Centrosome separation is impaired and microtubule asters are slightly smaller than normal. Centrosomes and microtubule asters are seen to stay at the cortex above nuclei which are displaced interiorly.

thr^ΔVQ.Tag:MYC has embryo | maternal effect | embryonic stage 5 phenotype, suppressible by Sse^13m/Sse[+]