Expression of en^hs.3 using a heat pulse 5-6 hours after egg laying at 25^oC results in ectopic NB 7-3 formation in 20% of hemisegments. The ectopic NB 7-3 is also able to give rise to characteristic progeny cells; additional serotonergic neurons are seen in 20% of the hemineuromeres of first instar larvae. A loss of eve-positive EL cells is seen. No additional NB 7-3 cluster is seen when en^hs.3 is expressed using a heat pulse 4-5 hours after egg laying at 25^oC, although the central nervous system is very malformed.

Failed to induce programmed cell death (PCD) in Df(3L)H99 embryos.

Heat shock during cellular blastoderm and early gastrulation causes pattern defects similar to those in embryos lacking en function. Heat shock during cellular blastoderm causes variable head defects, missing mouthparts, and abnormal, fused or missing denticle belts. Heat shock during gastrulation causes a series of defects in segmentation, from denticle belt fusions to a pair rule-type phenotype. Most prevalent fusions are A2 fused to A3, A4 fused to A5 and A6 fused to A7, similar to en⁴.