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Biomedical subjects

M Kiper

Publications and source records attributed to M Kiper.

10 recordsLinked to original sources
PubMed1980

Light-induced appearance of polysomal poly(A)-rich messenger RNA during greening of barley plants.

Changes in polysomal poly(A)-rich mRNA during greening of etiolated barley plants were studied by the technique of cDNA-mRNa hybridization. Hybridizaiton data of the homologous reactions reveal that in etiolated as well as in greened shoots a complexity of 5 X 10(7) nucleotides or about 33000 different average-sized mRNAs are present. These are organized in different abundancy classes with 94% of the total complexicity present in each of the slowest reacting class representing rare messengers. Heterologous hybridizations indicate that 92% of all polysomal poly(A)-rich mRNAs in etiolated shoots are complementary to those of greened and 82% of 'green' poly(A)-rich mRNAs are complementary to white ones. It is shown that the abundant mRNA clases are essentially responsible for these differences. The prevalent classes making up 15% ('white') and 31% ('green') of the poly(A)-rich mRNA mass but comprising only a complexity of 1.8 X 10(4) and 2.1 X 10(4) nucleotides are identical to 50% with each other. Hybridization of isolated prevalent 'green' cDNA with whole 'white' poly(A)-rich mRNA indicates that the additionally appearing 50% prevalent green messengers must be regarded as green-specific, only present in polysomal poly(A)-rich mRNA after illumination. This conclusion is underlined by the hybridization of the 'green' cDNA with total polysomal RNa of etiolated shoots. Evidently appearance of these prevalent messengers in functional polysomes is not caused by a shift from poly(A)-free mRNA to poly(A)-rich mRNA. The results clearly demonstrate that light induces greening by turning on genes or influencing post-transcriptional processing to produce mature green-specific poly(A)-rich mRNA.

Hordeum↗
PubMed1979

The expression of a plant genome in hnRNA and mRNA.

Representation of genomic kinetic sequence classes and sequence complexities were investigated in nuclear and polysomal RNA of the higher plant Petroselinum sativum (parsley). Two different methods indicated that most if not all polysomal poly(A) -RNA is transcribed from unique sequences. As measured by saturation hybridization in root callus and young leaves 8.7% and 6.2%, respectively, of unique DNA were transcribed in mRNA corresponding to 13.700 and 10.000 average sized genes. Unique nuclear DNA hybridized with an excess of polysomal poly(A)mRNA to the same extent as with total polysomal RNA. 3H-cDNA - poly(A)mRNA hybridization kinetics revealed the presence of two abundance classes with 9.200 and about 30 different mRNAs in leaves and two abundance classes with 10.500 and 960 different mRNAs in callus cells. The existence of plant poly(A)hnRNA was proven both by its fast kinetics of appearance, its length distribution larger than mRNA, and its sequence complexity a few times that of polysomal RNA.

Base Sequence↗
PubMed1978

A quick hydroxyapatite chromatography technique especially adapted for work with DNA networks.

During the renaturation of DNAs large networks build up which cannot be eluted from hydroxyapatite under standard fractionation conditions (60 degrees C, 0.5 M PB). This is a serious problem especially in plant-DNA renaturation studies as hyperpolymers may comprise more than half of the renatured DNA mass even at moderately long initial fragment lengths and low C0t values. Utilizing the acid solubility of hydroxyapatite a method is outlined which will recover the total double-stranded DNA fraction and will prepare the column for the next fractionation in one quick operation. As the method is time saving compared to the standard hydroxyapatite fractionation procedure its general application may prove to be useful.

Biopolymers↗
PubMed1976

The reconstitution of Anacystis nidulans DNA-dependent RNA polymerase from its isolated subunits.

The DNA-dependent RNA polymerase of the blud-green alga Anacystis nidulans was reconstituted from its isolated subunits in the absence of urea. Applying this technique the kinetics and the subunit requirements of the reconstitution process were analyzed. The results reveal differences with respect to the reconstitution of Escherichia coli polymerase. Reconstitution proceeds much more slowly in the case of the A. nidulans enzyme. Reconstitution here is absolutely dependent on the presence of the subunit sigma. On the other hand, the largest of the subunits of Mr=190000 can be fully substituted by a specific degradation product of this subunit of Mr=175000. Heterologous reconstitution between subunits of E. coli and A. nidulans polymerase does not result in active enzyme hybrids, showing a divergent evolution of the structure of this enzyme in these procaryotic organisms.

Binding Sites↗