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J Kruh

Publications and source records attributed to J Kruh.

117 records · Page 7Linked to original sources
PubMedDate not supplied

Early effects of triidothyronine on the complexity of rat heart messenger RNAs.

Triiodothyronine (T3), injected daily into rats, induces heart hypertrophy. In a recent work we have shown that a single T3 injection stimulates RNA synthesis and modifies the translational products of myocardial mRNAs in reticulocyte lysates, quantitatively and qualitatively. In this work we show that T3 induces small but significant changes in mRNA size distribution after 4 h and much more important changes after 18 h. It also modifies the size distribution of their poly(A) tails. We studied the early effects of this compound on mRNA complexity, using the nucleic acid hybridization technique with DNA complementary to poly(A)+ RNAs. T3, 4 h after injection, suppresses approximately 15% of the sequences, mostly among rare sequences, and increases the frequency of the abundant sequences and of the sequences of intermediary abundance. A large part of this effect disappears 18 h after the injection. It may be concluded that T3 presents an early effect on gene expression, involving changes either at the gene level or and at some post transcriptional level.

Animals↗
PubMedDate not supplied

The protein kinases tightly bound to DNA are present in normal tissues and in regenerating liver, but strongly decreased in hepatomas.

We have previously described in rat liver two protein kinases tightly bound to DNA, one is serine-specific, the other arginine-specific. In this work we show that both enzymes are present in various rat tissues and in liver from various species. Both kinase specific activities are strongly decreased in methyl-DBA-induced hepatomas and in HTC cells but not in regenerating liver after hepatectomy. This decrease is then not related to cell proliferation.

Animals↗
PubMedDate not supplied

Phosphorylation and protein kinase activities of chromosomal non histone proteins from chick embryo fibroblasts.

Confluent chick embryo fibroblasts were cultured in vitro in (i) medium which prevented the cells from dividing, (ii) medium which stimulated the cells to divide synchronously, (iii) medium without lysine in which the cells were blocked in G1. Chromosomal non histone proteins (NHP) were extracted from cells pulse labelled with 32P phosphate, and the radioactivity analyzed by acrylamide gel electrophoresis. Several radioactive peaks were found all along the gel in the NHP from confluent and stimulated cells. The highest phosphorylation was found in the fast moving proteins, but the stimulation of the cells increases the phosphorylation of the slower moving proteins. In the NHP from cells cultured in the medium without lysine only the slow migrating proteins were phosphorylated. NHP were extracted from unlabelled cell cultures in the three different media, incubated with [gamma-32P] ATP and analyzed by acrylamide gel electrophoresis. Highly labelled peaks were observed in the fast moving proteins from stimulated cells and from cells cultured in a medium deprived from lysine. By comparing in vivo and in vitro phosphorylation, it can be concluded that in confluent cells the turnover of bound phosphate is slow. In stimulated cells there is a fast turnover of the phosphate bound to fast turnover of the phosphate bound to a small group of fast migrating proteins and very little turnover of the phosphate bound to slow migrating proteins. The cells were incubated with labelled lysine and NHP analyzed by gel electrophoresis. The radioactivity of individual NHP varied with the culture conditions, but in all cases, there was little radioactivity in the fast moving proteins. The phosphate groups submitted to a fast turnover are bound to stable proteins. Phosvitin and casein kinase activities were measured in the NHP fractions. Nine-ten peaks of activities were observed with each substrate. Some variations were observed which apparently correlate with the culture conditions.

Adenosine Triphosphate↗
PubMedDate not supplied

Conformational change of core particles studied by quasielastic light scattering.

The diffusion translational coefficient Dt of core particles in monodisperse solutions has been measured by the quasielastic light scattering method in a large scale of salinities over the range 6.10(-4) to 2M Na+ or K+. The observed values of DT are independent of particle concentration in the range 0.1-2 mg/ml and do not vary with the scattering vector q corresponding to scattering angles between 40 degrees -120 degrees. When the salinity is progressively raised an increase of DT from 1.9.10(-7) cm2s-1 to 3.2.10(-7) cm2s-1 was observed at about 2.10(-3) M NaCl followed by a decrease of DT beyond 0.6 M NaCl.

Animals↗
PubMedDate not supplied

In vitro, non enzymatic labelling of histone H1 with [14C] acetyl CoA.

Histones H 1A and H 1B, in nuclear homogenates or after purification, are able to be acetylated or labelled by [14C] acetyl CoA in the absence of enzyme, as shown after blotting into nitrocellulose sheets. The reaction is pH-dependent, resistant to 2 M NaCl and does not occur at high ionic strength.

Acetyl Coenzyme A↗