Md. Peterson et al., The embryonic expression pattern of labial, posterior homeotic complex genes and the teashirt homologue in an apterygote insect, DEV GENES E, 209(2), 1999, pp. 77-90
During embryogenesis of the fruit fly, Drosophila melanogaster, the homeoti
c genes are required to specify proper cell fates along the anterior-poster
ior axis of the embryo. We cloned partial cDNAs of homologues of the Drosop
hila homeotic gene teashirt and five of the homeotic-complex (HOM-C) genes
from the thysanuran insect, Thermobia domestica, and assayed their embryoni
c expression patterns. The HOM-C genes we examined were labial, Antennapedi
a, Ultrabithorax, abdominal-A and Abdominal-B. As the expression pattern of
these HOM-C genes is largely conserved among insects and as Thermobia is a
member of a phylogenetically basal order of insects, we were able to infer
their ancestral expression patterns in insects. We compare the expression
patterns of the Thermobia HOM-C genes with their expression in Drosophila a
nd other insects and discuss the potential roles these genes may have playe
d in insect evolution. Interestingly, the teashirt homologue shows greater
variability between Thermobia and Drosophila than any of the HOM-C genes. I
n particular, teashirt is not expressed strongly in the Thermobia abdomen,
unlike Drosophila teashirt. We propose that teashirt expression has expande
d posteriorly in Drosophila and contributed to a homogenization of the Dros
ophila larval thorax and abdomen.