Expression of hb^hs.PS using brief heat shock late in the competence window for NB7-1 neuroblasts to make U1/U2 neurons produces very few ectopic hb[+] U1/U2 neurons.

A heat-shock induced pulse of hb^hs.PS expression just before the birth of the U1/U2 lineage results in a high proportion of hemisegments having ectopic U neurons. Progressively later pulses of hb^hs.PS expression generate a decreasing frequency of ectopic U1/U2 neurons.

When hb^hs.PS is expressed at 3.5-5.5 hours of development using heat shock, several ectopic U1 and U2 neurons are generated. When hb^hs.PS is expressed at 6.0-8.0 hours of development using heat shock, one ectopic presumptive U2 neuron is generated and as the heat shock is given progressively later, there is a gradual decline in the production of presumptive U2 neurons, until no response to hb expression is detected.

Embryos heat shocked during the syncytial blastoderm stage give rise to larvae lacking or having severely reduced abdominal segmentation.

Lam^sz18, hb^hs.PS has larval DO1 motor neuron | ectopic | heat sensitive phenotype

Lam^sz18, hb^hs.PS has larval DO2 motor neuron | ectopic | heat sensitive phenotype