Isolation of stable ribosomal subunits from spores of Bacillus cereus.

Analyses of ribosomes extracted from spores of Bacillus cereus T by a dryspore disruption technique indicated that previously reported defects in ribosomes from spores may arise during the ribosome extraction process. The population of ribosomes from spores is shown to cotain a variable quantity of free 50S subunits which are unstable, giving rise to slowly sedimenting particles in low-Mg2+ sucrose gradients and showing extremely low activity in in vitro protein synthesis. The majority of the ribosomal subunits in spores, obtained by dissociation of 70S ribosomes and polysomes, are shown to be as stable as subunits from vegetative cells, though the activity of spore polysomes was lower than that of vegetative ribosomes.

Radiation-induced chromosome aberrations in somatic and germ cells of the male marmoset.

The induction of chromosome aberrations by low LET radiations was studied in peripheral lymphocytes and spermatogonial stem cells of the male marmoset. The data showed that there was not significant difference in the sensitivity of the lymphocytes whether they were irradiated in vitro or in vivo, but the frequency of heritable translocations recovered in the primary spermatocytes were considerably lower than that calculated to occur in the lymphocytes. The data are used to make estimates of human genetic risk from radiation based on limited interspecific comparisons.

The effect of cytosine arabinoside on the frequency of single-strand breaks in DNA of mammalian cells following irradiation or chemical treatment.

1-beta-D-Arabinofuranosyl cytosine (araC), a pyrimidine nucleoside analog used in the treatment of malignant tumors [1, 2], inhibits ultraviolet repair of DNA in a reversible manner. The inhibition occurs during the resynthesis-ligation step and is apparent at all sites undergoing repair. By use of araC it was possible to substantiate the reported observation that the initial velocities of ultraviolet repair are dose dependent and that hamster and human cells are more efficient that mouse cells in excising DNA damage after fluences of less than 50 J/m2.

Vacuum ultraviolet radiation scales: an accurate comparison between plasma blackbody lines and synchrotron radiation.

Blackbody limited lines of C and N from an argon wali-stabilized arc have been used to determine the spectral radiance of specially developed deuterium discharge lamps at 165.7 nm, 167.0 nm, 174.

Electrophysiological and horseradish peroxidase studies of precerebellar afferents to the nucleus interpositus anterior. I. Climbing fiber system.

The input to the nucleus interpositus anterior (NIA) of the cat from the inferior olive (IO) was studied by stimulating the IO while recording intracellularly from the NIA, and by the retrograde transport of horseradish peroxidase (HRP). Stimulation of the IO evoked monosynaptic EPSPs in NIA neurons. The cells labeled in the IO following electrophoretic and pressure injection of HRP into NIA were located in the rostral parts of the dorsal and medial accessory olive.

X-Ray-induced translocations in spermatoginia. II. Fractionation in mice.

The dose-response curve for reciprocal translocations induced by X-rays in spermatogonial stem cells, and observed in primary spermatocytes of mice, is "hump-shaped", with a maximum yield at about 600 R. To test the hypothesis that the decrease in yield with increasing dose above 600 R is a consequence of the different sensitivities of cells in different stages of the cell cycle to both cell killing and chromosome aberration induction, several fractionation experiments were carried out. A total dose of 2800 R was given in repeated doses of 400 R, separated by 8-week intervals.

Efferent nerve fibers associated with the outermost supporting cells of the organ of Corti in the guinea pig.

In whold-mount preparations of the organ of Corti nerve fibers are sometimes seen peripheral to the third-row outer hair cells where they appear to wander among the Hensen cells. These fibers were studied in the guinea pig by both light and electron microscopy. In the upper second, third and fourth cochlear turns nerve fibers were seen between and on the peripheral side of the third-row Deiters cells as well as in the floor of the outer tunnel space.

X-ray-induced chromosome aberrations in mouse dictyate oocytes. I. Time and dose relationships.

Structural chromosome aberrations were analyzed in superovulated metaphase-I oocytes of the mouse, Mus musculus, at various times after a single acute dose of 200 R of X-rays. The aberrations seen were of the chromatid type, i.e.

Cytoplasmic fibrils in plasma cell leukemia.

In a patient with plasma cell leukemia, associated with pleural effusion, ultrastructural studies of the peripheral blood plasma cells showed an abundance of cytoplasmic fibrils. The nature of fibrils was not clarified, but they were not amyloid fibrils. This finding, coupled with a liaterature review, suggests that the cytoplasmic fibrils in plasma cells may be an additional cytological feature of this rare form of leukemia.

Studies on chemically induced dominant lethality. I. The cytogenetic basis of MMS-induced dominant lethality in post-meiotic male germ cells.

Young adult male mice were injected intravenously with doses of methyl methanesulfonate(MMS) ranging from 25 to 100 mg/kg body weight. These males were serially mated to superovulated females from day 1 post injection to day 23 post injection. The morning after mating (about 4-6 h post-copulation) the females were sacrificed and ova flushed from the ampulla.

Cochlear innervation in the guinea pig. II. The spiral tunnel bundle.

The organization of nerve fibers in the spiral tunnel bundle (STB) of the guinea pig organ of Corti has been studied by light and electron microscopy. In the basal turn STB fibers were found to run toward the base or apex in about equal numbers while in the upper turns they ran predominantly in an apical direction. Long spiral fascicles of 100 microns or more in length were abundant in the third and fourth turns, but were rarely seen in the lower turns.

Incorporation of radioactive calcium into otolithic membranes and middle ear ossicles of the gerbil.

45CaCl2 was injected into gerbils in single or multiple doses, and the resulting radioactivity in serum, otoconial CaCO3, bone samples, and selected labyrinthine epithelium was determined by liquid scintillation spectrometry. Incorporation into both utricular and saccular otoconia occurred at the rate of 0.06-0.

6-mercaptopurine, an inducer of cytogenetic and dominant-lethal effects in premeiotic and early meiotic germ cells of male mice.

Dominant-lethal effects of 6-mercaptopurine on male mice were studied using eight doses, ranging from 150 to 482 mg/kg. Effects of the 150-mg/kg dose were studied over the entire spermatogenic cycle, and those of the higher doses for matings made between days 28.5 and 41.

Utilization of nitrogen from soybean meal, casein, zein, and urea by mature sheep.

The utilization of nitrogen contained in soybean meal, casein, zein, and urea was studied in 12 mature wethers. Net microbial synthesis rates during the 6-hour period after feeding corresponded to ruminal ammonia concentrations, suggesting that the ruminal ammonia level in these experiments was a limiting factor in microbiol protein synthesis. Maximum conversion of dietary nitrogen to microbial nitrogen in the rumen during a 24-hour period was estimated to be 62.

Comparative response of castrate and intact male rats to diethylstilbestrol.

Treatment of castrate and intact male rats with DES in the feed was used to note its comparative effect on feed intake vesicle, testicle, spleen and liver weights, and DES similarly reduced gain and feed efficiently in both castrate and intact male rats. Thus, there appears to be a basic difference in the response of rats to DES, compared to cattle and sheep, that does not depend on whether they are intact or castrate males.