Biomedical subjects

H Steller

Publications and source records attributed to H Steller.

58 records · Page 4Linked to original sources

PubMed1985

Fate of DNA injected into early Drosophila embryos.

Plasmid DNA injected into early Drosophila embryos becomes enclosed in nuclei or nucleus-like structures where it remains at least throughout embryonic development. The fraction remaining in the cytoplasm is gradually degraded. The nuclear fraction is converted to a high-molecular-weight form consisting largely but not exclusively of tandem oligomers. Some of it, however, can occasionally become integrated in the genome. Extensive DNA replication takes place but few, if any, molecules are able to initiate a second round of replication.

Animals↗

PubMed1985

A 43 kilobase cosmid P transposon rescues the fs(1)K10 morphogenetic locus and three adjacent Drosophila developmental mutants.

The K10 female sterility locus involved in establishment of the embryonic dorsoventral axis maps genetically to the 2E2-2F1 interval of the Drosophila X chromosome. We microdissected the 2E2-2F3 region from salivary gland chromosomes and used clones obtained from the microdissected fragments to establish a chromosomal walk covering more than 200 kb. To identify the K10 gene we used P-mediated transformation with cosmid clones constructed in cos-P, a cosmid vector incorporating the terminal repeats of the P element. Clone cos9, containing a 43 kb insert, transformed the germ line of homozygous K10 females and allowed production of normal progeny. It also rescued three genes, crooked neck, pecanex, and kurz, which map genetically near K10. Transformation experiments using smaller fragments of cos9 localize the K10+ function within 11 kb. Northern blots hybridized with probes from this region indicate the presence of several mRNA species. Each transcript has been assigned to a complementation group.

Alleles↗

PubMed1984

Regulated expression of genes injected into early Drosophila embryos.

DNA of cloned genes injected into 15-30 min Drosophila embryos reaches nearly all the cells of the later embryo and its expression can be detected by Northern blot hybridisation. The injected DNA continues to be expressed at least up to the first instar larval stage and some developmental control of expression is retained. Genes normally expressed in the embryo are strongly transcribed upon injection while genes characteristic of later stages are not, or only very weakly expressed. Some transcription was detected with a larval salivary gland secretion gene (sgs-4) and with the adult promoter of the alcohol dehydrogenase gene (Adh) but not from the Adh larval promoter or from larval cuticle genes. A foreign gene (Semliki Forest virus capsid protein) was used to monitor the activity of promoters attached to it. In situ immunofluorescence of thin sections showed that the copia promoter is active mostly in yolk cells. In contrast, the hsp-70 heat-shock promoter is active, upon heat-shock, in nearly all cells in the embryo but most of the injected DNA is gradually lost so that in first instar larvae only 15% of the cells still express it.

Aldehyde Dehydrogenase↗

PubMed1984

Cloning of heat-shock locus 93D from Drosophila melanogaster.

Using the microcloning approach a number of recombinant lambda phages carrying DNA from the 93D region have been isolated. Screening genomic libraries, cloned in phage lambda or cosmid vectors, with this isolated DNA yielded a series of overlapping DNA fragments from the region 93D6-7 as shown by in situ hybridization to polytene chromosomes. In vitro 32P-labelled nuclear RNA prepared from heat-shocked third instar larvae hybridized specifically to one fragment within 85 kb of cloned DNA. The region which is specifically transcribed after heat shock could be defined to a cluster of internally-repetitive DNA and its neighbouring proximal sequences. Over a sequence of 10-12 kb in length the DNA is cut into repeat units of approximately 280 nucleotides by the restriction endonuclease TaqI. The TaqI repeat sequences are unique in the Drosophila genome.

Animals↗