Ectopic expression of h does not affect cell number in the stalks between egg chambers.
Expression of hhs.P2 in a pulsing heat-shock regime from 3rd instar larval to pupal stages produced eyes with varying areas of defects, depending on when the heat-shock was administered. Two distinct phenotypes were seen, a change in facet shape and size, and the presence of extra mechanosensory bristles. The change in facet shape and size is often present as a distinct zone (including at least 6 rows of ommatidia). The position of this zone in the eye from posterior to anterior is directly dependent on the age of the animal at the time of heat-shock. 24% of ommatidia are abnormal, with a range of phenotypes: too many photoreceptors, too few photoreceptors, and fused rhabdomeres.
Heat induced h expression causes two classes of cuticular patterns defects. One is 'pair-rule' embryos display pair-wise fusions of adjacent metameres. The second show more extreme deletions, in particular fusion of A2-A7 denticle bands to produce a 'lawn' embryo. The temperature sensitive period for each phenotype has been determined. Heat shock 5-20 minutes before gastrulation produces the pair-rule phenotype alone, 20-35 minutes before gastrulation produces the pair-rule and lawn phenotype and 35-50 minutes before gastrulation produces the lawn phenotype alone.
