Change of resistance to lysozyme and ultrasonic disintegration of the mycelium of Streptomyces griseus under the influence of chelating agents and polyvalent cations

Mycelia of Streptomyces griseus strain No. 52-1 from a 2-day submerged culture pretreated with ethylenediaminetetraacetic acid (EDTA) were digested with lysozyme. The sensitivity of younger vegetative hyphae to lysozyme increased while that of older reproductive hyphae remained almost unchanged.EDTA or borate pretreatment increased resistance to ultrasonic disintegration in the case of 96-h mycelia from submerged culture. EDTA was most effective at a concentration of 10−5 M.The enhanced resistance to ultrasonic disintegration can be reversed by Mg2+ and Al3+ in a concentration of 10−5 M, while Ca2+ ions are ineffective.These results suggest the existence of a polyvalent-ion-dependent layer in the cell wall of streptomycetes. Such a layer would be exterior to the mucopeptide layer. Its thickness changes during the life cycle and it is most prominent in younger vegetative hyphae.

Requirements for macromolecular synthesis in the establishment of beta-galactosidase repression in zygotes

Inhibitors of protein synthesis do not consistently prevent formation of the lac operon repressor, according to several published reports, although direct evidence indicates that the repressor is a protein. Inhibition of ribonucleic acid (RNA) synthesis has never been shown to block lactose repression. These results have raised the possibility that repressor is synthesized in some unusual fashion. We have studied the effect of various inhibitors upon the establishment of repression in zygotes, utilizing conditions which minimize catabolite repression. Inhibition of protein synthesis by either chloramphenicol treatment or tryptophan deprivation blocked repressor formation in our experiments. Sodium borate and 6-azauracil are compounds reported to be specific inhibitors of RNA synthesis, and their behavior in control experiments is consistent with this specificity. Both delayed the establishment of repression. Thymine deprivation, either by starvation of a thymine auxotroph or by treatment with 5-fluorodeoxyuridine, did not delay the onset of repression. We conclude that repressor formation requires RNA synthesis and probably utilizes the usual protein-forming mechanisms.

Evidence for a streptomycin permease

Hurwitz, Charles (Veterans Administration Hospital, Albany, N.Y.), and Carmen L. Rosano. Evidence for a streptomycin permease. J. Bacteriol. 90:1233-1237. 1965.-The hypothesis that an induced streptomycin permease is required for entry of the antibiotic into cells is further supported by the finding that proflavine and borate, which inhibit transcription, also block the lethal action of streptomycin. Furthermore, if ribonucleic acid (RNA) synthesis is permitted to proceed in the presence of streptomycin and chloramphenicol, and chloramphenicol is then replaced with either proflavine or borate, these inhibitors of transcription no longer block the lethal action of streptomycin. This finding is interpreted to mean that, if induced messenger RNA for streptomycin-permease is formed before transcription is blocked, inhibitors of transcription no longer block the lethal action of streptomycin by preventing formation of the permease.

Growth of Allescheria boydii in anitbiotic-containing media

Cazin, John, Jr. (University of Iowa, Iowa City), and David W. Decker. Growth of Allescheria boydii in antibiotic-containing media. J. Bacteriol. 90:1308-1313. 1965.-Thirteen isolates of Allescheria boydii were surveyed for their ability to grow and sporulate on media containing cycloheximide and chloramphenicol. The fungus grew well in the presence of 4 to 8 mg/ml of cycloheximide, whereas ascocarps and coremia were always inhibited at a concentration of the drug lower than that required to inhibit growth and conidial production. In certain strains, ascocarp production was inhibited by concentrations of cycloheximide (0.4 mg/ml) normally used in selective media; however, two strains produced mature ascocarps at a concentration of 1 mg/ml of the antibiotic, and two strains produced immature ascocarps at a concentration of 4 mg/ml. Growth inhibition was not observed with concentrations of chloramphenicol as high as 1,000 mg per liter in any of eight strains tested.

The effect of boric acid on the reaction of lead tetraacetate with polysaccharides in films and tissue sections

1. A preferential reaction of lead tetraacetate and boric acid with vic-glycols having the cis-configuration was investigated with a view to developing a more specific histochemical method for polysaccharides and glycoproteins.

2. With this objective, the effect of boric acid on the oxidation of polysaccharides and glycoproteins by lead tetraacetate in glacial acetic acid, as revealed by subsequent staining with aldehyde reagents, was studied in films of purified polysaccharides incorporated in gelatine (`Model' Preparations) and in tissue sections containing the same or similar compounds.

3. The staining intensity of `Model' Preparations was measured quantitatively by means of a recording microdensitometer.

4. In `Model' Preparations the reactions of galactogen, mannan, and alginic acid, all having reactive adjacent cis-hydroxyl groups, were compared with those of glycogen, and a partially hydrolysed dextran, both assumed to contain only reactive adjacent trans-hydroxyls. In parallel experiments sections of the following tissues were studied: albumin gland of Helix pomatia; liver, tracheal cartilage, thyroid gland, and mixed pharyngeal glands of the mouse.

5. Boric acid partially blocked the oxidation of mannan and galactogen but the oxidation of alginic acid was unaffected. Thus, while boric acid could exert its effect irrespective of whether the reactive hydroxyls were its a single chain or in branch chains, the character of the groups in close proximity to the reactive hydroxyls greatly influenced the reaction.

6. At room temperature lead tetraacetate oxidized glycogen and dextran much less readily than either mannan, galactogen, or alginic acid. Whereas boric acid had a slight blocking affect on the oxidation of glycogen at room temperature, the oxidation of dextran was probably not significantly affected. However, at 50°C. the blocking effect of boric acid was marked in the case of glycogen and appreciable its the case of dextran. This result was unexpected.

7. Galactogen in the albumin gland and glycogen in the liver reacted similarly to the purified materials. The oxidation of cartilage matrix (A) and material present in mucous alveoli (B) of the pharyngeal glands was partially (A) or completely (B) blocked by boric acid, but the reaction of basement membranes and serous alveoli was not affected; nor was the vigorous reaction of thyroid colloid.

8. In `Model' Preparations it was demonstrated that boric acid competed with lead tetraacetate for reactive groups and protected them from oxidation; but, because of adsorption of lead tetraacetate, it could not be shown unequivocally that in the presence of boric acid less lead tetraacetate was consumed in the oxidation of polysaccharide.

9. The apparently anomalous reactions of glycogen and dextran with boric acid may be due to complex formation with pairs of cis-hydroxyl groups, which, though in the same hexose radical, are not adjacent. Despite this, it is claimed that the use of lead tetraacetate its combination with boric acid is a valuable histochemical technique for revealing the presence of reactive adjacent cis-hydroxyl groups in polysaccharides and glycoproteins.