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G Steinbrück

Publications and source records attributed to G Steinbrück.

18 recordsLinked to original sources
PubMed1981

Characterization of macronuclear DNA in five species of ciliates.

Macronuclear DNA of four hypotrichous and one holotrichous ciliate species was characterized by biochemical techniques. The renaturation kinetics of the macronuclear DNAs of all five species were similar. Repetitive sequences occur only in an amount below 2%. Although the DNA content of the macronuclei of the species differs considerably, the kinetic complexity of the macronuclear DNA is rather uniform (around 3 x 10(10) daltons, i.e., 4-11 x the E. coli genome). Only in the macronuclei of the hypotrichous species the DNA exists as gene-sized fragments.

Animals↗
PubMed1978

Histone genes in macronuclear DNA of the ciliate Stylonychia mytilus.

DNA in the macronucleus of Stylonychia mytilus exists as discrete gene-sized fragments which are derived from micronuclear DNA through a series of well-defined developmental events. It has been proposed that each of the DNA fragments might represent a gene and its controlling elements. We have investigated this possibility using genes which code for the five histone proteins. Macronuclear DNA fragments were fractionated according to size by agarose gel electrophoresis, the fragments transferred to nitrocellulose filters using the technique of Southern, and the filter-bound DNA hybridized with labeled cloned histone genes of the sea urchin, Psammechinus miliaris. Results indicate, first, that sequences homologous to the five individual histone gene probes are present in discrete macronuclear fragments which appear as bands in the gel hybridization assay. Secondly, for each of the five individual histone gene probes the homologous DNA fragments are several in number, ranging in size in from 7.6 Kb (Kilo base pairs) to 0.73 Kb. For example, the largest of six detected fragments hybridizing to the H3 gene probe contains approximately 10 times the amount of DNA required to code for a Stylonychia H3 histone. The smallest detected fragment hybridizing to the H3 probe contains enought DNA to code for approximately two copies of the histone. Finally, in general, no two histone approximately two copies of the histone. Finally, in general, no two histone gene probes hybridized to the same macronuclear DNA fragment. This result indicates that genes coding for the five histones in Stylonychia are not located together on the same macronuclear DNA fragments and implies that the five functionally related genes would not be transcribed together as a polycistronic unit.

Animals↗
PubMed1978

Free genes for rRNAs in the macronuclear genome of the ciliate Stylonychia mytilus.

When separated on an agarose gel, macronuclear DNA of the hypotrichous ciliate Stylonychia mytilus gives rise to many well-defined bands ranging in molecular weight from 0.3 x 10(6) to 14 x 10(6) dalton. Hybridization of 25 S rRNA, 17S rRNA or 5 S RNA to such a gel revealed sharp hybridization bands. This suggests that this banding pattern is not an artefact due to nonspecific degradation of macronuclear DNA but that the DNA in the macronucleus of Stylonychia occurs in discrete fragments, each coding for at least one gene. The size of the DNA fragment coding for rRNA was found to be 4.5 x 10(6) dalton, the fragment coding for 5 S RNA has a molecular weight of 150,000-250,000 dalton.

Animals↗
PubMed1978

Chromatin structure in the macronucleus of the ciliate Stylonychia mytilus.

Evidence is presented that macronuclear chromatin in the hypotrichous ciliate Stylonychia mytilus occurs in discrete fragments, each representing at least single genes. The size of these fragments varies between 3 and more than 70 nucleosomes with an average length of about 18 nucleosomes. This observation is discussed with respect to macronuclear structure of hypotrichous ciliates.

Animals↗