Molecular mechanisms of EGF signaling-dependent regulation of pipe, a gene crucial for dorsoventral axis formation in Drosophila

During Drosophila oogenesis the expression of the sulfotransferase Pipe in ventral follicle cells is crucial for dorsoventral axis formation. Pipe modifies proteins that are incorporated in the ventral eggshell and activate Toll signaling which in turn initiates embryonic dorsoventral patterning. Ventral pipe expression is the result of an oocyte-derived EGF signal which down-regulates pipe in dorsal follicle cells. The analysis of mutant follicle cell clones reveals that none of the transcription factors known to act downstream of EGF signaling in Drosophila is required or sufficient for pipe regulation. However, the pipe cis-regulatory region harbors a 31-bp element which is essential for pipe repression, and ovarian extracts contain a protein that binds this element. Thus, EGF signaling does not act by down-regulating an activator of pipe as previously suggested but rather by activating a repressor. Surprisingly, this repressor acts independent of the common co-repressors Groucho or CtBP

THE ECOLOGY AND MORPHOLOGICAL VARIATION OF MARITES PHYLLODISTOMUM UMBLAE AND PHYLLODISTOMUM FOLIUM (TREMATODE: GORCODERIDAE) - PARASITES OF FISHES, THE BAIKAL LAKE BASIN

The work is aimed at studying the ecology and morphology of the two indicated species of the phyllodistoma and its influence on the micromorphology of the fishes excretory system. Investigated has been the morphological variation and distribution of the marites in the excretory system of the final hosts. The dynamics of the fishes infection with the phyllodistoma has been studied. The micromorphological variations of the fishes excretory system with the invasion by phyllodistoma have been describedAvailable from VNTIC / VNTIC - Scientific & Technical Information Centre of RussiaSIGLERURussian Federatio