Immunofluorescent study of histone H5 in chick erythroid cells from developing embryos and adults

Indirect immunofluorescence has been used to detect the presence of histone H5 in single cells during avian erythropoiesis. Evidence is presented which demonstrates that this method specifically detects histone H5. The results show that the increase in the amount of H5 which can be extracted from nuclei during erythropoiesis is accounted for both by an increase in the amount of H5 per cell and by an increase in the total number of cells containing histone H5. Of particular interest are the observations that histone H5 is arranged within the nucleus in several distinct, reproducible patterns and that different patterns predominate at different stages of erythroid cell development. In addition to suggesting new possibilities for the role of histone H5, these findings indicate that immunofluorescence may be used profitably to explore the supramolecular organization of chromatin.

Histone H5 in nucleated erythrocytes of fish as determined by radioimmunoassay

Tissue-specific histone H5 in the nucleated erythrocytes of dogfish, scup, skate, tautog, sea robin and toad fish was studied. The presence of this histone was inferred by its electrophoretic mocility on polyacrylamide gels containing either acid-urea or sodium dodecyl sulfate. By radioimmunoprecipitation assays, cross reaction was observed between fish histones and an anti-H5chicken antibody. The antibody was specific to chicken histone H5; purified chicken histone H1 and calf thymus total histones did not cross react. It is concluded that fish histone H5 shares common antigenic determinants with the chicken H5 histone.

An evaluation of Tween 80 effects on the survival and DNA repair in Escherichia coli following UV or gamma irradiation

The notion that Tween 80 may be a DNA-repair inhibitor was tested with Escherichia coli. The results indicate that cell growth, colony-forming ability, and the rate and extent of removal of thymine-containing dimers from DNA are unchanged in the presence of Tween 80. We conclude that this detergent does not increase or diminish the effect of UV or gamma irradiation to bacteria.

Single strand breakage and repair in eukaryotic DNA as assayed by S1 nuclease

A sensitive new approach for measuring the repair of single strand breaks in DNA induced by low doses of gamma irradiation was tested in cultured fibroblasts from Chinese hamster lung, human afflicted with ataxia telangiectasia or Fanconi's anemia and in normal cells of early and late passages. The assay is based on the increasing rate of strand separation of DNA duplexes in alkali for molecules with increasing numbers of single strand scissions. DNA strand separation is shown to follow the relation, in F = -(1/Mn - const) - tbeta where F is the proportion of double-stranded DNA, detected as S1 nuclease resistant, after alkaline denaturation time, t. Mn is the number-average molecular weight of DNA between single strand breaks. beta less than 1 is an empirically determined constant. The results suggest an increase in the number-average molecular weight between breaks, Mn, with increasing times for repair. The final level attained corresponds to the Mn of control DNA in unirradiated cells. As few as one break introduced into 109 daltons of single-stranded control cell DNA can be detected. The kinetics, requirements and sensitivities of this assay are described.

Lack of mutagenicity of vinyl chloride in two strains of Neurospora crassa

No detectable induction of mutations could be found in two strains of Neurospora crassa after their conidia were treated with vinyl chloride, in ethanol solution and in its gaseous form. The results suggest that although N. crassa seems to lativating systems does not increase mutagenic activity of vinyl chloride in the two strains tested. At the same time these strains were mutated easily by UV and methyl methanesulfonate.

Proliferative capacity of cell cultures derived from the human placenta

The placenta consists largely of fetal tissue, yet at term it displays histological signs of deterioration not apparent in the fetus. To determine whether the apparent degeneration of the placenta is genetically determined, the life-spans of placental cell cultures and the proportion of placental cells capable of incorporating [3H]thymidine for replicative DNA synthesis in vitro were measured. Under the culture conditions employed, the placental cells were removed from the influence of many extrinsic factors thought to play a role in the degeneration of the placenta in vivo. Cultures of fibroblast-like cells derived from the placenta exhibited a reduced life-span and correspondingly reduced proportion of cells able to incorporate [3H]thymidine for DNA synthesis in comparison to cultures derived from the fetal skin and the maternal decidua. These results suggest that intrinsic cellular processes may be involved in the apparent degeneration of the placenta.

Further resolution of adult chick hemoglobins by isoelectric focusing in polyacrylamide gel

Evidence is presented that adult chick hemoglobins exist in four types separable by isoelectric focusing on polyacrylamide gels instead of the two hemoglobin types previously resolved by other methods. These are hemoglobin A1 (HbA1), hemoglobin A2 (HbA2), hemoglobin D1 (HbD1), and hemoglobin D2(HbD2). Their pI values are 7.53 +/- 0.02, 7.37 +/- 0.02, 6.92 +/- 0.04 and 6.72 +/- 0.05, respectively, constituting about 63, 14, 18 and 5% of the total hemoglobin from adult chick erythrocytes, respectively. HbA1 and HbA2 ar identical in size, as determined on sodium dodecyl sulfate gels and similar in their amino acid composition and tryptic peptides. The molecular weight and amino acid composition of HbD1 and HbD2 are also identical although there are differences in their tryptic peptides. Experiments were done to show that the existence of four hemoglobin types is not due to genetic heterogeneity of the experimental animal, nor to artifacts of oxidation of carboxyhemoglobin to methemoglobin tetramers. Care was exercised to eliminate deamination and modification of side chain amino groups by using freshly prepared hemolysates and to minimize the "plateau phenomenon" peculiar to isoelectric focusing by controlling the duration of electrophoresis. The use of cyanmet form of (thus liganded) hemoglobin in this study reduced the chance of heterotetramer formation. Furthermore, consideration was given to possible anomalies caused by ampholytes. In the face of negative evidence for artifacts, it is concluded that adult chicken has more than the two hemoglobin types previously reported.

Protein requirements of men in a hot climate: decreased urinary nitrogen losses concomitant with increased sweat nitrogen losses during exposure to high environmental temperature

In two separate experiments 8 healthy young men were given an egg-milk formula at a level of 0.7 g protein/kg per day, and were exposed to high environmental temperature (34--37 C, 7 hours daily) or cool temperature (21--26 C, all day), alternately. In the first experiment a 16-day hot period was followed by a 20-day cool period and finally by a 20-day hot period. Daily urinary nitrogen (N) loss of the last 8 days of cool period, 82.2 mg/kg, was significantly higher than that of the last 8 days of the 20-day hot period 69.7 mg/kg. Daily skin N loss was significantly lower during the last 8 days of the cool period (3.5 mg/kg) than during the last 8 days of the 20-day hot period (11.9 mg/kg). Urinary N and skin N lossess were negatively correlated (r equal to -0.905) in these periods. In the second experiment a 28 day hot period was followed by a 20-day cool period. Skin N loss diminished from 12.3 mg/kg daily during the last 12 days of the 28-day hot period to 4.1 mg/kg during the last 12-days of the cool period. At the same time, urinary N loss increased significantly from 81.4 mg/kg during the 28-day hot period to 95.2 mg/kg during a cool period. Urinary N and skin N losses were again negatively correlated (r equal to -0.620) during these periods. Results of these studies indicate that when skin N loss increases during high temperature, urinary N loss decreases gradually, but total N loss does not increase.

Studies on interaction between histone V (f2c) and deoxyribonucleic acids

Histone V (2fc) from chick erythroctes was used in the study of its interaction with DNA from various sources. Complexes between this histone and DNA were formed using the procedure of continuous NaCl gradient dialysis in urea. Two physical methods, namely thermal denaturation and circular dichroism (CD), were used as analytical tools. Thermal denaturation of nucleohistone V with chick or calf thymus DNA shows three melting bands: band I at 45-50 degrees corresponds to free base pairs; band II at 75-79 degrees, and band III at 90-93 degrees correspond to histone-bound base pairs. In histone-bound regions, there are 1.5 amino acid residues/nucleotide in nucleohistone V. In contrast, a value between 2.9 and 3.3 was determined for nucleohistone I (fl) (H. J. Li (1973), Biopolymers 12, 287). Similar melting properties have been observed for histone V complexed with bacterial DNA from Micrococcus luteus. Histone V binding to DNA induces a slight transition from a B-type CD spectrum to a C-type spectrum. Trypsin treatment of nucleohistone V reduces melting band III much more effectively than band II. Such a treatment also restores DNA to B conformation in the free state. Reduction of the melting bands of nucleohistone V by polylysine binding follows the order of I greater than II greater than III, accompanied by the increase of a new band at 100 degrees. When two bacterial DNAs of varied A + T (adenine + thymine) content simultaneously compete for the binding of histone V, the more (A " T)-rich DNA is selectively favored. Under experimental conditions described here, Clostridium perfringens DNA with 69% A + T is bound by histone V in preference to chicken DNA with 56% A + T although the latter has natural sequences for histone V binding.

Regional neurochemical studies on the effect of beta, beta'-iminodipropionitrile (IDPN) in the rat

A permanent hyperkinetic syndrome, characterized by excitation, choreiform head and neck movements and circling, which has led to it being called collectively the "ECC-syndrome," is induced in rats by the daily IP administration of beta, beta'-iminodipropionitrile (IDPN), 300 mg/kg, for 7 days. The levels of the biogenic amines, norepinephrine (NE), dopamine (DA), serotonin (5-HT) and its metabolite 5-hydroxyindoleacetic acid (5-HIAA), were measured in the striatum, midbrain, medulla, cortex, and cerebellum on the day the syndrome appeared (day 7) and one week later (day 14). The biogenic amine most affected by IDPN administration was 5-HT. On day 7, striatal 5-HT levels increased and 5-HIAA levels decreased while in the medulla and midbrain, 5-HIAA levels increased. On day 14, significant reductions in both 5-HT, in the midbrain, striatum, and cortex, and 5-HIAA, in all regions except the cortex, were observed. NE was markedly increased in the medulla, midbrain, and striatum on day 7, whereas on day 14 it was found to be within the normal range in these same regions. With the exception of a slight, but significant, increase in the cortex on day 7, DA levels in all regions were found to be relatively unaffected by IDPN administration on both day 7 and day 14. In an attempt to detect degenerative changes which might be taking place in the brain and which might provide an explanation for the permanency of the behavioral disturbances, the uptake of [3H]-labeled NE, DA, and 5-HT into synaptosomal-rich preparations of striatum and the uptake of NE and 5-HT into the midbrain area were compared between normal and syndromized rats on both day 7 and day 14. Small changes were observed but they were not statistically significant. The alterations of 5-HT and 5-HIAA levels in several regions of the brain under the conditions examined may indicate that IDPN's neurotoxicity primarily affects 5-HT-containing neurones. The active membrane transporting system of the nerve endings studied, however, remained relatively intact. This latter finding eliminates the possibility that neuronal degeneration in these areas is responsible for the decreased 5-HT and 5-HIAA levels or is the pathology underlying the permanency of the syndrome. These results are evaluated in terms of a possible model for hyperkinetic disorders.

New chromatographic form of phenylalanine transfer ribonucleic acid from Escherichia coli growing exponentially in a low-phosphate medium

Reversed-phase chromatography has been used to detect the presence of a new form of phenylalanyl-transfer ribonucleic acid (Phe-tRNA) from Escherichia coli growing exponentially in media containing low but nonlimiting levels of inorganic phosphate. The amount of this extra Phe-tRNA form is greatest in slowly growing cells (0.8 generations/h), and becomes negligible in media supporting a rapid growth rate (2.14 generations/h).

Purification and properties of the cathepsin D types proteinase from beef and rabbit lung and its identification in macrophages

The acid-acting proteinase, cathepsin D (EC 3.4.4.23), was purified from extracts of homogenized rabbit lung and beef lung by autolysis at acid pH, acetone and ammonium sulfate fractionation, column chromatography, and isoelectric focusing. Four isoenzymes were obtained from each source. With acid hemoglobin as the substrate, the proteinase from rabbit lung had a pH optimum of 3.0 and that from beef lung had a pH optimum of 3.6. Their activity was not affected by thiol reagents or by Fe(2+), Mn(2+), or Mg(2+). One isoenzyme from rabbit lung was used to immunize a goat, and one from beef lung was used to immunize a rabbit. In immunoelectrophoresis, each resulting antiserum formed a single precipitin line with its homologous enzyme. They cross-reacted with the other three isoenzymes from the same species, but not with any isoenzyme from the other species. At high concentrations, each antiserum completely inhibited the proteolytic activity of its homologous enzyme. The antiserum against rabbit lung cathepsin D also inhibited the proteolytic activity of rabbit peritoneal and pulmonary macrophages. In limited quantities, this antiserum has now been made commercially available and is being used with labeled antibody techniques to identify under a microscope the presence of cathepsin D in macrophages and to study its role in the pathogenesis of tuberculosis.

Ribosomal RNA synthesis in vitro: a protein-DNA complex from Bacillus subtilis active in initiation of transcription

A protein-DNA transcription complex, isolated from logarithmic-phase cells of Bacillus subtilis, is active in the initiation of new rounds of RNA synthesis in vitro. Transcription directed by the endogenous DNA of the complex is sensitive to inhibitors of initiation. In addition, the effect of addition of a competing template indicates that RNA polymerase in the complex is bound to endogenous DNA in a dissociable, preinitiation state. Hybridization-competition analysis of the RNA product obtained from the in vitro reaction indicates that it is greatly enriched for ribosomal RNA sequences. This initiating complex should be useful for the study of regulation of expression of ribosomal RNA genes.

Identification of competence-repressing factors during log-phase growth of Haemophilus influenzae

Metabolic factors that suppress development of competence in Haemophilus influenzae during growth in the synthetic medium MI(c) have been identified. These include inosine, nicotinamide adenine dinucleotide, glycerol, and uracil. It is also possible to initiate competence in the presence of these substances if the oxygen tension in the culture is temporarily reduced.

Time-dependent effects of inosine on competence development in Haemophilus influenzae

The effect of inosine on the development of competence is dependent upon the time at which it is added to the competence medium. Competence is inhibited if inosine is added within 15 min after the development begins, but is stimulated if the addition is made at later times. Protein synthesis is stimulated by the addition of inosine, but the effect is quantitatively similar regardless of the time at which inosine is added.

In vivo uptake of [14C]leucine by skeletal muscle ribosomes after injury in rats fed two levels of protein

1. After 14 days on a diet containing 5 or 25% casein male rats received a fracture of the left femur. Four hours before they were killed the injured and control rats were injected with [1-14C]leucine; the incorporation of radioactivity into an isolated fraction of skeletal muscle ribosomes was studied 6, 12, 24, 48, 72, 96 and 228 h after injury.

2. The incorporation of [14C]leucine into the ribosome fraction in right thigh muscles dropped to 40% of control values 72 h after fracture in well-nourished rats and after 96 h with diets containing 5 or 25%, casein.

3. The specific activity of the trichloroacetic acid-soluble fraction of muscle from injured rats was equal to or higher than that of the controls during the first 72 h but lower at 96 h.

4. These results suggest that a reduced incorporation of amino acids by ribosomes from the right thigh muscle occurred on day 3 after fracture in the group receiving 25% casein but not in the group receiving 5% casein.

5. Muscle RNA and DNA concentrations were not affected by the injury.

6. The relationship between these findings and the loss of muscle N after injury is discussed.