It is widely held that the bilaterian tubular gut with mouth and anus evolved from a simple gut
with one major gastric opening. However, there is no consensus on how this happened. Did …

Background The heads of annelids (earthworms, polychaetes, and others) and arthropods
(insects, myriapods, spiders, and others) and the arthropod-related onychophorans (velvet …

Background Arthropods are the most diverse animal phylum, but their genomic resources
are relatively few. While the genome of the branchiopod Daphnia pulex is now available, no …

Changes in the expression of Hox genes have been widely linked to the evolution of animal
body plans, but functional demonstrations of this relationship have been impeded by the …

Aphids exhibit unique attributes, such as polyphenisms and specialized cells to house
endosymbionts, that make them an interesting system for studies at the interface of ecology …

The head gap genes orthodenticle (otd), empty spiracles (ems) and buttonhead (btd) are
required for metamerization and segment specification in Drosophila. We asked whether the …

Recent advances in genetic manipulation and genome sequencing have paved the way for
a new generation of research organisms. The amphipod crustacean Parhyale hawaiensis is …

Background Transcription factors that determine retinal development seem to be conserved
in different phyla throughout the animal kingdom. In most representatives, however, only a …

Germ cells are a population of cells that do not differentiate to form somatic tissue but form
the egg and sperm that ensure the reproduction of the organism. To understand how germ …