PubMed Health⌕ Search

Biomedical subjects

D Pallotta

Publications and source records attributed to D Pallotta.

49 records · Page 3Linked to original sources
PubMed1976

Analysis of the genome of plants. II. Characterization of repetitive DNA in barley (Hordeum vulgare) and wheat (Triticum aestivum).

Barley and wheat DNAs have been characterized by studying their kinetics of reassociation, melting properties and sedimentation behaviour in neutral CsCl gradients as well as in Cs2SO4 gradients containing Ag+ or Hg2+. In both species, reassociation kinetics have revealed the presence of approx. 76% redundant nucleotide sequences which have been grouped into very rapidly reassociating (Cot 0-0.01), rapidly reassociating (Cot 0.01-1.0) and slowly reassociating (Cot 1-100) fractions. The barley Cot 0-0.01 and Cot 0.01-1.0 fractions as well as the wheat Cot 0.01-1.0 fraction form narrow bands upon centrifugation in CsCl gradients. Under similar experimental conditions both Cot 0.01 and Cot 1.0-100 wheat fractions and the barley Cot 1.0-100 fraction form broad bands each having several shoulders. Thermal denaturation studies of most of the above reassociated fractions have shown a considerable degree of order in their duplexes with an average hyperchromicity of 21.5%. When native, high molecular weight barley DNA is centrifuged in Ag+/CS2SO4 density gradients (RF = 0.2), two satellites appear on the heavier side of the main band, as against one in the case of wheat. The two minor peaks, designated as satellites I and II, have buoyant densities of 1.702 and 1.698 g/cm3, respectively, in neutral CsCl gradients and together represent about 8-9% of total barley DNA. Upon centrifugation in Hg2+/CS2SO4 density gradients, one satellite is observed in both barley and wheat and it accounts for 1-2% of their genomes.

DNA↗
PubMed1976

A study of the interaction between ethidium bromide and rye chromatin: comparison with calf thymus chromatin.

We studied the interaction of ethidium bromide with rye and calf thymus chromatin. Both types of chromatin have the same dye accessibility, which is about 50% of that of DNA. From this result we conclude that the molecular structure of these two chromatins is similar. For rye, the extraction of H1 produces no change in the binding of ethidium bromide. The subsequent extraction of H2A and H2B produces a 14% increase in the binding, and the removal of H3 and H4, another 54% increase. At this stage, the number of binding sites is still less than that of DNA. This is presumably due to the presence of some tightly bound non-histones. Thus, the arginine-rich histones and the tightly bound non-histones are most responsible for limiting the binding of ethidium bromide to rye chromatin.

Animals↗
PubMed1976

Amino acid composition of sperm histones in the house cricket Acheta domesticus.

Histones were isolated from late spermatids and spermatozoa of the house cricket Acheta domesticus, and the individual histone fractions were separated by electrophoresis on polyacrylamide-urea gels. The stained gels were cut so as to isolate the different histone fractions, and the amino acid compositions were determined using the technique of Houston (Houston, L.L.: Anal. Biochem. 44, 81-88 (1971). Five of the histones had amino acid compositions resembling those for the histones of calf thymus and were thus identified as fractions F1, F3, F2a2, F2b, and F2al. Another protein (SH) located exclusively in the late spermatids and spermatozoa was found to be basic and histone-like. It is a protein containing relatively high amounts of arginine (12.6%) and low amounts of lysine (7.6%), and, as a result, it has a low ratio of lysine-arginine (0.6). Other noteworthy features are its high contents of serine, glutamic acid, and glycine. It is arginine rich histone and in this regard resembles other such proteins, but it does contain unique features which distinguish it from all previously described histones.

Amino Acids↗
PubMed1976

The selective extraction of histones from rye chromatin.

The selective extraction of histones from rye chromatin was studied using three different methods. Extractions with NaCl-phosphate buffers at pH5.5 gave results similar to those already obtained with other types of chromatin. Histone H1 was selectively extracted with 0.6 M NaCl-0.001 M PO4, while the selectivity of dissociation of the other fractions was reduced at higher NaCl concentrations. The use of phosphate-urea buffers at pH5.5 also revealed that the histones were dissociated at the same concentrations as were calf thymus histones. Histone H1 was extracted with 0.5 M PO4-1 M urea; H1, H2A, and H2B were extracted with 0.8 M PO4-2 M urea; and all histones were removed with 0.8 M PO4-5.3 M urea. It was, however, observed that the dissociated rye histones H2A and H2B were unstable in these buffers. This instability was maximum in the presence of 3 M urea, where both histones were absent from the extracted proteins and the residual nucleoproteins. Finally, a solution of 30% ethanol-0.35 M NaCl-6 M urea produced a rye nucleoprotein fraction containing only histone H1.

Animals↗
PubMed1969

Chromatin and histones: binding of tritiated actinomycin D to heterochromatin in mealy bugs.

The degree of actinomycin D binding to DNA in chromatin is dependent upon the state of repression of chromatin. Living cells bind three times more tritiated actinomycin to euchromatin than to genetically inactive heterochromatin. Extraction of histone results in a general increase in tritiated actinomycin binding and in a ratio of the uptake in heterochromatin to that in euchromatin approaching unity.

Animals↗