Presence of histone H1o-related fraction in chicken liver.

The lysine-rich histones of chicken liver were studied in order to see whether a protein similar to mammalian histone H1o was present in this lower vertebrate. The following biochemical methods were used: sodium dodecylsulphate and acid-urea electrophoresis, gel exclusion chromatography on BioGel P100, and ion-exchange chromatography on BioRex 70. Specific polyclonal antibodies were elicited against purified mouse liver H1o and chicken erythrocyte H5, and applied for the further characterization of the chicken H1 subfractions obtained chromatographically.

Metabolically stable ribonucleoproteins in the chromatin of pigeon bone marrow cells.

Ribonucleoproteins with buoyant density 1.4 carrying metabolically stable RNA species with sedimentation coefficients up to 28S have been detected in the 0.35M NaCl extracts from pigeon bone marrow chromatin.

Existence of differences in repressor properties between serine-rich histones (H5, F2c) from immature and mature pigeon erythroid cells.

The abilities of H1 and H5 histones from immature and mature pigeon erythroid cells and subfractions of H5 histones with different content of alkali-labile phosphorus to restrict RNA synthesis were compared in an in vitro transcription system with bacterial RNA polymerase. It has been found that: a) H1 histones from both sources exhibit similar efficiency. b) H5 histones from immature cells restrict transcription to a lesser extent than the same histone from the mature erythrocyte.

Purification and characterization of two transcribed repetitive DNA fractions from the pigeon genome.

Two fractions of the repeats belonging to intermediate frequency repetitive DNA were isolated from the total pigeon nuclear DNA fragmented to about 450 nucleotides. One fraction was designated as "rare repeats" (repetition frequency about 35 per haploid genome) and another termed as "moderate repeats" (repetition frequency about 2500 per haploid genome). The rare repeats, which constitute about 7% of the total DNA, include at least 75% of the repetitive DNA sequences transcribed into the high molecular fraction (greater than 45S) of HnRNA in erythroid cells.

Repetitive sequences and hairpin-like structures in giant RNA of pigeon erythroid cells.

In giant molecules (greater than 45 S) of HnRNA from pigeon bone marrow and peripheral blood erythroid cells a correlation is demonstrated between the amounts of hairpin-like structures and the sequences transcribed from the DNA repetitions. The same correlation is observed in the greater than 45 S poly(A)+ and poly(A)- subfractions.

Transcription of repetitive and unique DNA nucleotide sequences in pigeon erythroid cells with different degrees of specialization.

HnRNA fractions with sedimentation coefficients greater than 45 S isolated from pigeon bone marrow as well as from the immature and mature erythroid cells of periferal blood were hybridised with a large excess of DNA fractionated on the basis of renaturation kinetics. 58-62% of the input RNAs were recovered as RNAase-resistant hybrids. About 1/3 (20%) of bone marrow greater than 45 S RNA found in the hybrids was hybridised with the repetitive and baout 2/3 (40%) with the unique DNA sequences.

In vitro transcription of partially deproteinised and reconstituted chromatins from pigeon erythroid cells.

The role of protein fractions extracted from chromatin preparations with NaCl concentrations up to 0.7 M in the additional repression of pigeon erythrocyte genome was investigated. The chromatins from erythroblasts and erythrocytes were dissociated with 0.

Hybridization of pigeon globin messenger RNA with complementary DNA synthesized in vitro by reverse transcription: influence of the homopolymeric regions.

The kinetics of hybridization of pigeon globin messenger RNA with complementary cDNA synthesized by means of AMV reverse transcriptase is complex. Addition of poly A or poly U in excess to the reaction mixture normalized the kinetics. It is concluded that association of the complementary homopolymeric regions of mRNA and cDNA accelerates the complex formation between heteropolymeric sequences in a fraction of the molecules.