Characterisation of a selenophosphate synthetase from a collection of P-lacW insertion mutants in Drosophila
International Journal of Developmental Biology
We are interested in the regulation of cell proliferation and its role in development. As a model system we use the Drosophila imaginal discs development which shows extensive cell proliferation during larval stages. From a collection of P.lacWlethal insertion mutations in the second chromosome (Torok at al. 1993) we have selected those with a late larval lethal phase and lacking or with reduced or abnormal imaginal discs. Our rationale is that mutations with such phenotypic effects would
... effects would define genes somehow involved in cell proliferation. One of these mutations is the subject of the present study and has been characterised by a morphological analysis of the discs as well as by clonal analysis. Disc morphology is characterised by a reduced and unorganised mass of cells. No folding or patterning can be detected in none of the imaginal discs of the larval stages. Clonal analysis on wings has shown that homozygous clones, in a slow dividing (Minute-) background as well as in twin dones, have the following features: 1.-clones are small in overall size. 2.-cells of the clone are small, as deduced from the size of the trichomes. 3.-borders of the clones are rounded. 4.-vein differentiation is reduced where the clone crosses a vein. 5.-ectopic veins may appear adjacent to clones. 6. -reduction of the wing regions can be detected vvhen clones are in intervein regions. We also have checked for the presence of apoptotic cells in the imaginal discs of the homozygous larvae. Both the reduction of the clone size and the associated reduction of the intervein regions could be explained by an increase of cell death. Therefore we labelled the 3' terminus of putative fragmented DNA by means of labelled nucleotides incorporated by a terminal deoxynucleotidyl transferase. The results show abundant apoptotic cells in the reduced homozygous imaginal discs.