Association of protein amount polymorphism (PAP) among maize lines with performances of their hybrids

Summary It has been suggested that molecular foundations of phenotypic diversity reside in the variability of genome expression. This variability can be appraised through the polymorphism of individual protein amounts (PAP: protein amount polymorphism). Eight maize inbred lines and ten of their single-cross hybrids were analyzed by two-dimensional polyacrylamide gel electrophoresis in order to examine the potential of PAP for predicting hybrid vigor. The 28 possible pairs of lines were characterized for: (i) the number, H of expected heterozygous structural loci in their hybrid, in the sample of loci revealed by 2D-PAGE; (ii) four distance indices based on PAP; (iii) the hybrid values for five agromorphological characters measured in four different year/locations. For the subset of ten hybrids analyzed by 2D-PAGE, the number of cases of nonadditive inheritance (NA) was also counted. Whereas H appeared to be related neither to the PAP indices, nor to NA, nor to hybrid performances, PAP indices were correlated to NA, and both were positively associated to hybrid performances. The possibility that PAP is responsible for quantitative trait variation is discussed. This could result in the definition of biological predictors of heterosis.     

Phosphorylation state of protamines 1 and 2 in human spermatids and spermatozoa

The basic nuclear proteins of a fraction of elongating spermatids from human tests and of a fraction of motile spermatozoa from the ejaculate, separated by ion-exchange chromatography, were compared. Analysis by acetic acid-urea polyacrylamide gel electrophoresis (PAGE) showed that, in both fractions, four proteins of lower mobility were coeluted with protamine 1 by 23% guanidinium chloride (GuCI) while protamine 2 alone was eluted by 50% GuCI. Treatment with alkaline phosphatase identified those four proteins as phosphorylated protamines, and cyanogen bromide (CNBr) treatment of the dephosphorylated protamines distinguished them as variants of protamine 2 and not of protamine 1. Thus far, phosphorylated forms of protamine 1 have not been detected in either spermatids or spermatozoa. Those observations indicate that protamine 2 functions in the cycle of phosphorylation-dephosphorylation, which is essential to the process of sperm chromatin condensation, while the role of protamine 1 in human spermiogenesis is not yet defined. The presence of phosphorylated protamine in motile, presumably mature spermatozoa appears to be characteristic of human sperm but not of the sperm of other mammals and is probably the basis for the heterogeneity of chromatin condensation frequently observed in human spermatozoa.     

A minireview of microheterogeneity in H1 histone and its possible significance

Subtypes of H1 histone vary in primary structure, and the higher organisms that have been studied each seem to have about a half-dozen subtypes. The proportions of these subtypes vary with the progress of differentiation as seen in embryonic development, hormonally induced changes, spermatogenesis, and terminal differentiation. The H1 subtypes differ among themselves in their ability to condense DNA and small chromatin fragments. They have the potential, therefore, of causing different parts of the chromatin to be condensed to different degrees.     

Co-condensation between transcription factor and coactivator p300 modulates transcriptional bursting kinetics

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Cis-acting loci involved in the induction and reversal of chromosome condensation in plant prophase,determined by their different replication times

Summary Anoxic UVA irradiation (300–400 nm) of cells in prophase induced their chromatin to return to the interphase decondensed form when their DNA was unifiliarly bromosubstituted. This immediate effect may be related to the incompetence of chromatin with Br-DNA when irradiated to bind proteins which induce its condensation. Hence, inhibition of protein synthesis also causes chromatin decondensation in cells with native DNA.Bromosubstitution of DNA sequences replicated in the last two thirds of the S period was as efficient as bromosubstitution of the whole genome for such an effect to take place in a nucleus. On the other hand, the irradiation accelerated the entrance into prophase of those cells in which only sequences replicated in the first third of S were bromosubstituted. Thus, early replicating loci may act as attachment sites for binding proteins preventing the induction of chromatin condensation. DNA bromosubstitution during portions of S was carried out in synchronous cell populations labelled as binucleate by a previous short caffeine treatment, inAllium cepa L. root meristems.Abbreviations Br-DNA bromosubstituted DNA - BrUdR 5-bromodeoxyuridine - UVA 300–400 nm wavelengths light - p 34 34 kDa protein codified by genecdc 2 inS. pombe or its analogues in other species     

Chromatography of human urinary erythropoietin and granulocyte colony-stimulating factor on insolubilized phytohaemagglutinin

Human urinary erythropoietin was adsorbed to phytohaemagglutinin coupled to agarose or porous glass and quantitatively eluted by a saturated solution of MgCl₂. This method provides a means of separating erythropoietin from several of its contaminants, presumably on the basis of its carbohydrate side chains. Erythropoietin which had been purified by chromatography on insolubilized phytohaemagglutinin was sufficiently free of toxicity to be assayable in tissue culture even when crude urine was used as a starting material.     

Premature chromosme condensation in the bone marrow of Chinese hamster after application of bleomycin in vivo.

The Chinese hamster bone marrow was used as a test system in vivo to analyse the chromosome-danaging effect of bleomycin. Both chromosome and chromatid aberrations were found. Mitoses with aberrations (Ma) show a linear dose-effect relationship after a recovery time of 24 h, the same hold true for cells with micronuclei (Cm) and for mitoses with premature chromosome condensation (PCC). The dose-effect relationships for Ma, Cm and PCC run parallel to each other with Ma at the highest and PCC at the lowest level (Ma greater than Cm greater than PCC). The time-effect relationships for Ma, Cm and PCC show that after 12 h recovery time there are no PCCs but the highest frequencies of Ma and Cm indicating that most cells are in their first post-treatment mitoses or Gi-phases at this fixation time. In addition to the frequency determinations autoradiographic analysis were performed to clarigy the nature of the PCCs. The results are interpreted as follows: bleomycin induces chromosomal aberrations that in turn give rise to micronuclei by means of lagging chromatin, main and micronuclei eventually become asynchronous in their cell cycles and mitosing main nuclei induce PCC in the micronuclei.