Drosophila regulatory factor X is necessary for ciliated sensory neuron differentiation.

Ciliated neurons play an important role in sensory perception in many animals. Modified cilia at dendrite endings serve as sites of sensory signal capture and transduction. We describe Drosophila mutations that affect the transcription factor RFX and genetic rescue experiments that demonstrate its central role in sensory cilium differentiation. Rfx mutant flies show defects in chemosensory and mechanosensory behaviors but have normal phototaxis, consistent with Rfx expression in ciliated sensory neurons and neuronal precursors but not in photoreceptors. The mutant behavioral phenotypes are correlated with abnormal function and structure of neuronal cilia, as shown by the loss of sensory transduction and by defects in ciliary morphology and ultrastructure. These results identify Rfx as an essential regulator of ciliated sensory neuron differentiation in Drosophila.

Cytoplasmic actin A3 gene promoter injected as supercoiled plasmid is transiently active inBombyx mori embryonic vitellophages.

Freshly deposited eggs ofBombyx mori were microinjected with supercoiled plasmid DNA which carried the ß-galactosidase coding sequence ofEscherichia coli inserted in place of the coding sequence of theB. mori cytoplasmic actin A3 gene. Transient expression of this fusion gene in the embryo was determined by in situ histochemical detection of enzyme activity. After injection of the plasmid at different stages of embryonic development, ß-galactosidase activity depending on the injected DNA was only detected in the vitellophages. This indicates the presence of active transactivators of the actin A3 gene promoter in this cell type. Tissue specificity of the fusion gene expression could be related to the early polyploidization of vitellophages, a process which would favour the stability of the nuclear pool of injected plasmids. The activity of the transgene in vitellophages was detectable at 24-33 h of egg development, the stage presumed for the onset of zygotic gene expression, up to the end of embryogenesis. This gene transfer system is thus promising to analyse thecis regulatory sequences of the actin A3 gene and could be utilized for other ubiquitous genes.

The arrest of embryogenesis at gastrula stage in the diapausing silkwormBombyx mori is related to the synthesis of protein P61.

Two-dimensional protein gels are used to assess systematically changes in protein synthesis in diapausing and non-diapausing early embryos ofBombyx mori throughout natural breakage of diapause by chilling and after artificial prevention of diapause by HCl+ heat-shock treatment. A set of proteins, the heat-shock protein (hsp) 70 family previously described, was synthesized in diapausing and non-diapausing development at the early germ-anlage stage; by contrast, protein 61 (P61; 61 kDa) was synthesized only in the diapausing gastrula stage. The synthesis of P61 decreased during days at 5°C. Thereafter, we observed the synthesis of the hsp 70 family at 5°C. After the artificial prevention of diapause, P61 synthesis was not induced at the gastrula stage, whereas the hsp 70 family was enhanced in the 6 h following the preventive treatment. P61 was only synthesized after treatments were ineffective in preventing diapause and in inducing hsp 70. Thus, P61 can be described as a "diapause arrest-associated protein."