摘要:

A number of genetic loci, called neurogenic, have been found to be involved in directing the segregation of neural and epidermal lineages within the ectodermal germ layer ofDrosophila melanogaster. With the aim of understanding the regulation of this developmental function we have studied interactions of the lociN, DlandE(spl)among each other and with another locus(H), by means of increasing and decreasing the number of wild-type copies of one of these genes in the presence of mutations in another one. The results reveal functional community which exists among these neurogenic loci.E(spl)overlaps functionally with bothNandDlbecause genotypes involving only one copy ofE(spl)+and either anNorDlmutation are lethal. Furthermore the normalH+allele behaves as if it represses the activity of the 3 neurogenic loci; and, whereasE(spl)seems to be a close target ofHrepressing action, the influence ofHupon the other two seems to be indirect.

ISSN:0167-7063    

DOI:10.3109/01677068509102325

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

摘要:

Developmental studies have shown thatelavJ1mutants are temperature-sensitive for defects in retinula cell and optic lobe structure. Anatomical and physiological examination of mutants, shifted between permissive and restrictive temperatures, shows that the early pupal period is phenocritical for producing defects in retinula cells. Although this period precedes visible development of the rhabdomere, brief pulses to 29°C during this time result in characteristic abnormalities in rhabdomere structure. These studies also show that the temperature-sensitive effects on mutant optic lobe development begin prior to the effects on the retina, suggesting that theelavproduct participates directly in optic lobe as well as in retinula cell development.

ISSN:0167-7063    

DOI:10.3109/01677068509102326

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

摘要:

We have investigated the form I cyclic nucleotide phosphodiesterase (PDE) fromDrosophila melanogasterand shown that whereas heads and male thoraces and abdomens contain high levels of Ca2 +-stimulated enzyme, female thoraces and abdomens contain little Ca2 +-stimulated activity. The electrophoretic patterns of form I PDE from these 3 sources have also been studied and reveal that heads, and male thoraces and abdomens, produce two bands of form I PDE both of which are stimulated by Ca2+. Extracts of female thoraces and abdomens, on the other hand, show only a single, faster running band of PDE activity which is only marginally stimulated by Ca2+, if at all. Surveying wild-type strains ofDrosophilahas revealed that one strain, Swedish, shows altered electrophoretic mobility of the PDE band from female thoraces and abdomens. The alteration is such that the Swedish PDE band runs more anodally than the Oregon-R and Canton-S PDE activities. Mixing experiments, using co-homogenization of heads with female thoraces and abdomens, yeild a single faster running band on electrophoresis. This band contains only Ca2+-insensitive PDE. Attempts to reconstruct this loss of Ca2+-sensitive PDE without electrophoresis have failed. The Swedish electrophoretic variation of the PDE from female thoraces and abdomens has been found to be recessive with respect to the Canton-S phenotype, but the variation is observed to re-emerge and segregate with the third chromosome in the F2generation. The results indicate that electrophoretic variation in the form I PDE is, by itself, insufficient to allow the location of the structural gene for this enzyme.

ISSN:0167-7063    

DOI:10.3109/01677068509102327

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

摘要:

A cDNA library was efficiently synthesized from mouse neuroblastoma poIy(A)+RNA. Several modifications of the oligo(dC)(dG) tailing procedure were used. After first strand synthesis, a dATP tail was added to the 3′-end of the cDNA. The second strand was primed for synthesis with oligo(dT). Blunt ends were produced on the cDNA by treatment with S1 nuclease. Size-enriched fractions of high molecular weight DNAs were obtained by passing the cDNA over a Sepharose CL-4B column. The optimal tailing time for each cDNA fraction was individually tested. Tailing reactions used terminal deoxynucleotidyl transferase and annealing reactions used a (G)-tailed PstI cut pBR322.E. coliK12 RR1 cells were transformed and 2.5–5×106transformants perμg cDNA insert were obtained for each size fraction. The transformants had an average insert size of 1200 base pairs and were 98% ampicillin sensitive. Our modifications in the method for cDNA library synthesis had 3 advantages. (1) Homopolymer-primed cDNA treated with S1 nuclease allowed the blund ends to be tailed sychronously. This allowed a higher transformation efficiency without loss of 5′-sequences. (2)Time tailing determined the most efficient tail length and optimized the transformation efficiency in each size fraction. (3) A Sephadex G-50 mini-column was used to desalt and dry nitrogen was used to concentrate the ds cDNA instead of the usual ethanol precipitation. This resulted in almost 100% recovery of synthesized products at each step of this procedure.

ISSN:0167-7063    

DOI:10.3109/01677068509102328

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor