cact7 embryos exhibit a strong ventralized phenotype; the laterally derived cephalic fold initiates dorsally after the onset of gastrulation.
Homozygous and cact7/cactE10R01 mutant third instar larvae have melanotic nodules found in the hemocoel or in association with He-positive lymph glands. They also show gut melanisation not accompanied by tissue overgrowth or hemocyte encapsulation.
Approximately half of the melanotic nodules found in cact7 larvae are surrounded by lamellocytes, while the other half consist of tissue agglomerates that contain one or more melanised foci and also tube-like structures, which are possibly tracheae, visceral muscles and polyploid cells.
cact7 flies show similar mortality levels to wild-type flies in response to feeding with both the ROS-resistant KNU53775 yeast strain and a standard yeast strain (W303).
The concentration of circulating hemocytes in homozygous larvae is increased compared to controls. The fraction of podocytes and lamellocytes is increased compared to controls.
Lamellocytes appear in circulation during the second instar stage in cact7/cact3 larvae and are abundant in the hemolymph of third instar larvae (5-20%), where they participate in the formation of melanotic tumours. The crystal cell population is not affected. Lamellocytes are present in the lymph glands of third instar mutant larvae.
About 30% of cact7 heterozygotes die as embryos and show mostly a weak ventralised phenotype.
Larvae contain free-floating melanotic masses.
In the absence of immune challenge the antifungal gene Drs is constitutively expressed.
Homozygous females produce strongly ventralised embryos. Larvae exhibit a melanotic tumour phenotype. There is some lethality at the end of the larval stage.
Cell intercalation in lateralized cact mutant embryos proceeds normally during germ band extension.
72% of embryos from heterozygous mothers hatch, but none hatch in presence of additional dl protein. Females transheterozygous for a cact gain of function allele and a loss of function allele result in embryos in which ventral structures are progressively lost at the expense of dorsal structures as the strength of the loss of function allele increases.
Ventralized embryos: rings or patches of ventral denticles along dorsoventral axis, expansion of mesoderm at expense of ectoderm. Altered pattern of dpp and zen and expansion of twi and sna expression domain.
Strong ventralizing phenotype: lack of all dorsally and laterally derived structures and the expansion of the ventral epidermis around the entire circumference. Expansion of twi expression in terminal regions.