Purification and Characterization of an Autolysin from Clostridium acetobutylicum

A proteinaceous substance with antibiotic-like activity, resembling that of a bacteriocin, was isolated from an industrial-scale acetone-butanol fermentation of Clostridium acetobutylicum. The substance, purified by acetone precipitation, diethylaminoethyl cellulose chromatography, and polyacrylamide gel electrophoresis, was characterized as a glycoprotein with a molecular weight of 28,000. The glycoprotein was partially inactivated by certain protease enzymes. It had no effect on deoxyribonucleic acid, ribonucleic acid, or protein synthesis, and it did not result in the loss of intracellular adenosine triphosphate. The glycoprotein lysed sodium dodecyl sulfate-treated cells and cell wall preparations, and therefore it is referred to as an autolysin. The autolysin gene appeared to be chromosomal since plasmid deoxyribonucleic acid was not detected in the C. acetobutylicum strain.     

Characterization and phenotypic control of the cytochrome content of Escherichia coli

1. Electron-transport particles derived from Escherichia coli grown aerobically contain three b-type cytochromes with mid-point oxidation-reduction potentials at pH7 of +260mV, +80mV and -50mV, with n=1 for each. The variation of these values with pH was determined. 2. E. coli develops a different set of b-type cytochromes when grown anaerobically on glycerol with fumarate or nitrate as terminal electron acceptor. Electron-transport particles of fumarate-grown cells contain b-type cytochromes with mid-point potentials at pH7 of +140mV and +250mV (n=1). These two cytochromes are also present in cells grown with nitrate as terminal acceptor, where an additional cytochrome b with a mid-point potential of +10mV (n=1) is developed. 3. The wavelengths of the alpha-absorption-band maxima of the b-type cytochromes at 77K were: (a) for aerobically grown cells, cytochrome b (E(m7) +260mV), 556nm and 563nm, cytochrome b (E(m7) +80mV), 556nm and cytochrome b (E(m7)-50mV), 558nm; (b) for anaerobically grown cells, cytochrome b (E(m7) +250mV), 558nm, cytochrome b (E(m7) +40mV), 555nm and cytochrome b (E(m7) +10mV), 556nm. 4. Cytochrome d was found to have a mid-point potential at pH7 of +280mV (n=1). 5. Cytochrome a(1) was resolved as two components of equal magnitude with mid-point potentials of +260mV and +160mV (n=1). 6. Redox titrations performed in the presence of CO showed that one of the b-type cytochromes in the aerobically grown cultures was reduced, even at the upper limits of our range of electrode potentials (above +400mV). Cytochrome d was also not oxidizable in the presence of CO. Neither of the cytochromes a(1) was affected by the presence of CO.     

The cellular and humoral immune response to Schistosoma mansoni infections in inbred rats. V. Prerequisite mechanisms for the development of optimal protective immunity.

The mechanisms whereby natural infection or artificial immunization lead to the development of optimal protective immunity against reinfection by homologous Schistosoma mansoni were investigated. Animals, exposed to normal or irradiated cercariae, demonstrated strong resistance to reinfection by S. mansoni. They also developed a population of T lymphocytes, which could adoptively transfer resistance in vivo and specifically interact with immunogen in vitro. Subsequently these animals produced antibody capable of adoptively transferring resistance and possessing a variety of antischistosomal activities. Animals exposed to soluble cercarial immunogen demonstrated moderate resistance upon reexposure. They failed to produce a significant population of sensitized T lymphocytes. Moreover, although these animals produced unimpaired levels of cytotoxic, complement-fixing, and hemagglutinating antibody, their sera did not adoptively transfer resistance. Adult worm and egg immunogens were even less effective than cercarial immunogen in stimulating resistance. In addition, these membrane-derived immunogens directly stimulated B-lymphocyte blastogenesis in vitro. These studies suggest that the optimal production of protective immunity requires the stimulation of T-dependent mechanisms by stage-specific immunogens. This stimulation is produced more effectively by the use of natural infection or irradiated cercariae than by the use of soluble schistosome immunogens which may be working through relatively T-independent mechanisms.     

Effect of aeration on the flood-induced formation of adventitious roots and other changes in sunflower (Helianthus annuus L.)

Summary The effects of flooding, flooding with aeration, and no flooding of the root system on shoot growth was studied in sunflower plants. The responses of shoots appear to be brought about by: (1) The anaerobic condition of the roots which causes stem dwarfing, chlorosis, and petiolar epinasty. (2) The presence of water in excess of field capacity (but not anoxia) around the roots which results in an increase in stem hypertrophy and the formation and growth of adventitious roots.Abbreviations (F, NF, FA) are explained in Material and Methods.     

Excretion of inhibitors of calcification in urine Part II. Findings in patients with chronic renal failure.

By means of a semiquantitative method incorporating the rachitic rat cartilage technique, the total urinary inhibitory activity with respect to calcification was compared in 11 control subjects and 20 patients with renal failure. The patients had significantly lower mean values of inhibiting units per day than did the control subjects. Both groups showed a significant positive correlation between the number of inhibiting units per day and urine volume. When urine volume was taken into account in the comparison, the numbers of inhibiting units for patients continued to be lower than the numbers for controls. These findings are consistent with the hypothesis that the increase of inhibitory activity observed in uremic serum is secondary to a decrease in excretion of the responsible factor (or factors) in the urine, and that the factor (or factors) in serum responsible for the inhibition are identical to those in the urine.