The chemistry of insect hemolymph. III. Glycerol

Free glycerol has been identified as a major solute in plasma of pupae of the silk moth, Hyalophora cecropia. Glycerol is not found in the blood of larvae; it appears about the time of pupation, and then gradually accumulates during diapause to reach after 6 months a level of about 0.3 M. When diapause is broken and the adult develops, glycerol rapidly disappears. In diapausing pupae of the related species, Telea polyphemus, about 0.05 M glycerol was found; in 3 other saturniid species, there was little or none. It is suggested that glycerol may be a product of a modified glycolytic pathway.

A note on glycerol formal as a solvent in toxicity testing

Twenty-nine organic solvents and emulsifying agents, selected for possible use as injection solvents in toxicity testing, have been submitted to a “range-finding” toxicity screening test on rats. As a result, glycerol formal was examined in greater detail. Glycerol formal is a good inert solvent for a wide range of organic chemicals. It produced no toxic effects or macroscopic pathology when 1500 mg./kg. was administered intraperitoneally to rats, or 1000 mg./kg. to mice or guinea pigs, or 4000 mg./kg. orally to rats, and at high doses the only specific effect found was narcosis. It was correspondingly innocuous subcutaneously or dermally, and was almost non-irritant to the eye surface. There was no detectable effect on the toxicity of parathion. Glycerol formal appears to be a useful addition to the range of solvents suitable for use in toxicity tests.

Oxidation of glycerol by Streptococcus faecalis

Claridge, C. A. (Merck Sharp & Dohme Research Laboratories, Rahway, N.J.) and David Hendlin. Oxidation of glycerol by Streptococcus faecalis. J. Bacteriol. 84:1181-1186. 1962.-The nature of the factors in yeast autolysate essential for the oxidation of glycerol by Streptococcus faecalis F24 was examined. Two factors appear to be involved in the oxidation of glycerol. One factor was shown to be an inducer of the enzyme system required for glycerol oxidation; the other was shown to be alpha-lipoic acid. Minute quantities of glucose will "spark" growth of S. faecalis in a medium containing glycerol and acetate as carbon sources, probably by supplying sufficient energy for induction of the glycerol-oxidation system.

A SYSTEM FOR STUDYING MICROBIAL MORPHOGENESIS: RAPID FORMATION OF MICROCYSTS IN MYXOCOCCUS XANTHUS

A method has been found for inducing the rapid, quantitative, and relatively synchronous conversion of vegetative rods of a fruiting myxobacterium to microcysts. The conversion is induced by the addition of 0.5M glycerol to a dispersed, growing, liquid culture of Myxococcus xanthus. The vegetative rods are converted to microcysts in about 120 minutes.

PHYSIOLOGY OF THE ENTEROCOCCI AS RELATED TO THEIR TAXONOMY

Deibel, R. H. (American Meat Institute Foundation, Chicago, Ill.), Donald E. Lake, and C. F. Niven, Jr. Physiology of the enterococci as related to their taxonomy. J. Bacteriol. 86:1275-1282. 1963-Studies on a collection of enterococci isolated from diverse sources have confirmed the existence of two distinct species, namely, Streptococcus faecalis and Streptococcus faecium. In contrast with S. faecium, S. faecalis characteristically ferments melezitose, sorbitol, glycerol (anaerobically), citrate, and gluconate; fails to ferment arabinose and melibiose; has strong reducing capacities as demonstrated by prompt reduction of litmus in milk or tetrazolium in an agar medium; initiates growth on an agar medium containing 0.04% potassium tellurite; does not require folic acid for growth; and does not produce strong greening in blood agar. S. liquefaciens and S. zymogenes differ from S. faecalis only in their proteolytic capacities and, therefore, deserve only varietal status. Some S. faecalis and S. faecium strains are proteolytic when tested on agar media. S. durans differs from S. faecium only in its inability to ferment arabinose and mannitol, and the failure of most strains to ferment sucrose. Therefore, it should be considered as a variety of S. faecium. It is recommended that the term "enterococcus" be used only when referring to S. faecalis and S. faecium, and their respective varieties.

LIPIDS OF DEBARYOMYCES HANSENII

Merdinger, Emanuel (Roosevelt University, Chicago, Ill.), and Edward M. Devine, Jr. Lipids of Debaryomyces hansenii. J. Bacteriol. 89:1488-1493. 1965.-The separation of neutral lipids and phospholipids from the lipid extract of Debaryomyces hansenii NRRL Y-1448 was accomplished by using a single column packed with silicic acid. The neutral lipids comprised 67%, and the phospholipids 33%, of the total lipid extract. Qualitative and quantitative characterization of the lipids was effected by various analytical procedures. Gas chromatography of the fatty acid methyl esters showed 11 acids, of which 59.7% were unsaturated. The most abundant among the unsaturated acids was the monounsaturated C18 acid (50.1%). Among the saturated acids, palmitic acid (23.5%) prevailed. Ratios of fatty acid to glycerol, phosphorus to glycerol, and phosphorus to fatty acid were ascertained for combined cuts from the neutral lipids and the phospholipids. The presence of ergosterol, stigmasterol, and an unidentified sterol was established by gas chromatography. Also present were saturated hydrocarbons containing 16 to 39 carbon atoms, C22 being the most prevalent.

RELAXING EFFECTS OF FORMAMIDE ON GLYCERINATED MUSCLE FIBERS AND ON MYOSIN B SUSPENSION

Acetone induces a reversible relaxation of glycerinated muscle fibers (1). We found that formamide is equally effective. Since the dielectric constant of formamide is larger and that of acetone is smaller than that of water, the change in the dielectric constant of the fiber medium after adding organic solvents has little to do with the mechanism of this organic solvent-induced relaxation. That ITP can substitute for ATP in this relaxation suggests that organic solvents, when they induce a relaxation, act on the contractile protein rather than on ATP. Comparing the relaxing effect of 11 different organic solvents, the authors propose a working hypothesis based on the assumption of a specific interaction between organic solvents and the contractile protein. Formamide induces a "clearing" response of myosin B suspensions which is an in vitro model of muscle relaxation. Effects of Mg, Ca, and ionic strength (KCl) on this clearing response are studied in comparison with the effects of these on EDTA-induced relaxation. It is then shown that the formamide-induced clearing response is less specific than the EDTA-induced clearing response with regard to the requirements for ATP and Mg.

SWEETNESS PRODUCED ELECTRICALLY ON THE TONGUE AND ITS RELATION TO TASTE THEORIES

Electrical stimulation of the tongue under controlled conditions produces pure sensations of the four basic tastes. These basic tastes correspond to four kinds of papillae which are distinguished by differences in their anatomical structures, their frequency response curves, and the times required for the buildup of sensation, but which all have about the same chronaxie. Although these findings do not favor the cluster theory of taste perception, adaptation experiments indicate that they do not disagree with the microelectrode recordings of nervous discharges of taste fibers in the chorda tympani.

electrical taste; frequency response of the four specific taste buds; inhibition of taste sensations; interaction between taste buds; specific taste receptors; taste buds; taste units

Submitted on March 2, 1964

CAT HEART MUSCLE IN VITRO. V. DIFFUSION THROUGH A SHEET OF RIGHT VENTRICLE

The rate of transfer of labeled molecules across a sheet of quiescent cat right ventricle separating two chambers containing chemically identical solutions was followed at 23°C. For the diffusion of sucrose, SO₄, and Na the experimental points fit the entire time course of the plot of the diffusion equation for a plane sheet. The tortuosity factor of the extracellular diffusion channel, λ was 1.44 ± 0.05 (mean ± SEM) for sucrose and similar for SO₄ and Na. The fractional area available for extracellular diffusion, calculated from λ and the slope of the linear asymptote approached during steady state diffusion, was 0.17–0.23 for both impermeant species (sucrose, SO₄, Na) and permeant species (water, urea, glycerol). Permeant molecules showed a characteristic prolongation of the approach to the steady state, with an unexplained "hump" in the curve for water. The observed time courses for diffusion of permeant molecules are interpreted in terms of a model proposed by Fatt et al. for diffusion through linear porous media containing dead-end pore volume. Large molecules like inulin and dialyzed dextran (diameter 150 to 180 A) diffuse through the sheet. These molecules may have a reflection coefficient σ > 0. The fraction of muscle water occupied by the sucrose diffusion channel is significantly smaller than the 3 hr. mannitol, sucrose, and inulin spaces.

GLUCOSE CATABOLISM BY BACILLUS POPILLIAE AND BACILLUS LENTIMORBUS

Pepper, Rollin E. (Michigan State University, East Lansing), and Ralph N. Costilow. Glucose catabolism by Bacillus popilliae and Bacillus lentimorbus. J. Bacteriol. 87:303-310. 1964.-Resting cells of Bacillus popilliae and B. lentimorbus catabolize glucose with the production of CO(2), lactic acid, acetic acid, glycerol, ethanol, and trace amounts of acetoin and acetaldehyde. The first three products are the major ones, and their ratios may be varied by controlling the availability of oxygen. Practically no lactic acid is produced when oxygen is not limiting, whereas it may comprise up to 80% of the total acid when oxygen is greatly limited. However, no glucose is catabolized by resting cells in the absence of molecular oxygen. Isotope and inhibitor studies and assays for key enzymes of the established metabolic routes all indicate that these organisms utilize both the Embden-Meyerhof and hexosemonophosphate pathways for glucose dissimilation. With a concentrated resting-cell suspension, the extent of participation of the latter route was estimated to be as high as 40% in an atmosphere of pure oxygen, and as low as 2% in air. Acetate was oxidized by only one of the cultures of B. popilliae tested, which is apparently a mutant. Cells of this strain from stationary phase cultures oxidized acetate at pH 7.0 or higher, but not at pH 6.0; however, they oxidized succinate, fumarate, and malate more rapidly at pH 6.0 than at 7.0. The oxidation of tricarboxylic acid cycle intermediates, the presence of condensing enzyme in extracts of cells capable of oxidizing acetate, and the complete inhibition of acetate oxidation by arsenite and partial inhibition by malonate all indicate that terminal oxidation of acetate by this strain of B. popilliae is via the tricarboxylic acid cycle.

FUMARATE REDUCTION AND ITS ROLE IN THE DIVERSION OF GLUCOSE FERMENTATION BY STREPTOCOCCUS FAECALIS

Deibel, R. H. (American Meat Institute Foundation, Chicago, Ill.), and M. J. Kvetkas. Fumarate reduction and its role in the diversion of glucose fermentation by Streptococcus faecalis. J. Bacteriol. 88:858-864. 1964.-Fumarate diverts the normal fermentation of glucose by Streptococcus faecalis FB82, as shown by the production of increased amounts of CO(2), formate, acetate, and acetoin, and decreased formation of lactate and ethanol. Experiments with d-glucose-1-C(14), in which low levels of labeled CO(2) were recovered, indicated that C-1 cleavage of the glucose molecule was not involved. The presence of fumarate afforded consistently larger cell crops in growth studies with glucose and other energy sources. On a molar growth-yield basis, anaerobically grown, glucose-fumarate cultures were equivalent to aerobically grown, glucose cultures. The reduction of fumarate by cell suspensions indicated that glucose, gluconate, and, to a lesser extent, glycerol and mannitol could serve as hydrogen donors. Several common metabolic inhibitors had no effect upon the fumarate reductase system in cell suspensions, although some sensitivity to acidic pH was noted. Significant levels of succinate oxidation activity were not detected. Fumarate reductase activity was demonstrated in all five S. faecalis strains tested. Distribution of this ability in S. faecium strains was variable, ranging from activity comparable with that of S. faecalis to total inactivity. The observations support the conclusion that fumarate functions as an alternate hydrogen acceptor, thus allowing pyruvate to participate in the energy-yielding phosphoroclastic and dismutation pathways.

SOME OBSERVATIONS ON THE FINE STRUCTURE AND METABOLIC ACTIVITY OF NORMAL AND GLYCERINATED VENTRICULAR MUSCLE OF TOAD

Fine structure, enzyme activity, and transmembrane potentials of normal and glycerinated ventricular muscle of the toad were studied. For electron microscopy, osmium tetroxide and Araldite were used. Plasma membranes are firmly attached to Z bands. Both the T system and sarcoplasmic reticulum are poorly developed. Small bodies of medium density may be lysosomes derived from the Golgi zone. Denser bodies may be catecholamine granules. Fine tubules of unknown significance, about 200 A in diameter and of considerable length, lie in conspicuous, although infrequent bundles. Glycogen and mitochondria are abundant. After weeks of extraction in 50 per cent buffered glycerol, most organelles were still present, and much of the gross damage was probably due to osmotic destruction of membranes weakened by extraction. Many mitochondria were well preserved. Plasma and nuclear membranes had diffuse outlines and tended to be broken. Considerable activity remained of the enzymes succinic dehydrogenase, cytochrome oxidase, and phosphorylase after the extraction, but decreased with prolonged soaking. The normal transmembrane potential was about 95 mv; in extracted muscle after 6 weeks it was about 35 mv. The view that glycerinated muscle is a simple system of actin and myosin is clearly wrong. The activity of other organelles still present must affect the actions of many drugs and ions experimentally added.

CIRCUMVENTION OF THE MYCOBACTIN REQUIREMENT OF MYCOBACTERIUM PARATUBERCULOSIS

Morrison, Norman E. (Johns Hopkins University-Leonard Wood Memorial Leprosy Research Laboratory, Baltimore, Md.). Circumvention of the mycobactin requirement of Mycobacterium paratuberculosis. J. Bacteriol. 89:762-767. 1965.-The mycobactin growth requirement of Mycobacterium paratuberculosis was circumvented on glucose-containing synthetic medium with an initial pH of 5.5. Mycobactin was required during the first transfer on the synthetic medium. Subsequent transfers have grown in the absence of mycobactin. The growth of mycobactin-"independent" strains of M. paratuberculosis on the synthetic medium was found to be stimulated by low concentrations of mycobactin. The circumvention of the mycobactin requirement appears to depend upon the properties of the medium and not upon having created conditions which promote endogenous mycobactin synthesis. Investigation of the glucose-containing synthetic medium showed that: (i) growth stimulatory compounds were formed during autoclaving, and (ii) compared with neutrality a pH of 5.5 gave markedly increased pellicle yields. It was suggested that the growth-stimulatory compounds formed during autoclaving may in part be responsible for the circumvention of the mycobactin requirement.

ROLE OF MAGNESIUM IN CONTRACTION OF GLYCERINATED MUSCLE FIBERS

The first phase of the magnesium effect, the increase in tension with increasing concentration of magnesium, up to about 25 µm, is abolished by the metal chelators DCTA and EDTA, but not by EGTA. DCTA is much stronger than EDTA in abolishing this first phase. The second phase of the magnesium effect, the decrease in tension with increasing concentration of magnesium, from about 25 µm to about 1 mm, is reduced when the concentration of ATP is decreased from 5 mm to about 0.5 mm. The third phase, the increase in tension with increasing concentration of magnesium to above 1 mm, is also reduced by metal chelators. However, EGTA is the strongest and DCTA is the weakest in reducing this third phase. From these observations, it is suggested that the first and the second phases are due to Mg (probably in the form of Mg-ATP complex) and that the third phase reflects the effect of a small amount of Ca which has been well established ( J. Biochem., Tokyo 50: 236–244, 1961 and J. Biol. Chem. 234: 2764–2769, 1959).

THE INCORPORATION OF GLYCEROL AND LYSINE INTO THE LIPID FRACTION OF STAPHYLOCOCCUS AUREUS

1. Incubation of washed cells of Staphylococcus aureus with [1-(14)C]glycerol results in the incorporation of glycerol into the lipid fraction of the cells. The rate of incorporation is increased by the presence of glucose and amino acids. The presence of amino acids increases incorporation into the fraction containing O-amino acid esters of phosphatidylglycerol. 2. Glycerol, incorporated into washed cells by incubation with glycerol, glucose and amino acids, is rapidly released from the lipid fraction when cells are incubated at low suspension densities in buffer. 3. Of nine amino acids tested, only lysine is significantly incorporated into the lipid fraction. The incorporation is increased by the presence of glycerol, glucose and other amino acids, especially aspartate and glutamate. 4. The incorporation of lysine is increased by the addition of puromycin at concentrations that inhibit protein synthesis. Chloramphenicol does not increase the incorporation of lysine but abolishes the enhancing effect of puromycin. 5. The enhancing effect of puromycin is accompanied by a similar increase in the incorporation of lysine into the fraction soluble in hot trichloroacetic acid. 6. Lysine is incorporated into the lipid fraction that contains O-amino acid esters of phosphatidylglycerol and corresponds in properties to phosphatidylglyceryl-lysine. 7. Lysine is rapidly released from the lipid of cells incubated in buffer only at low suspension densities. 8. Incubation of cells with the phosphatidylglyceryl-lysine fraction does not lead to the appearance of free lysine or to incorporation into the fraction insoluble in hot trichloroacetic acid.

TAUTOMERIC FORMS OF METARHODOPSIN

Light isomerizes the chromophore of rhodopsin, 11-cis retinal (formerly retinene), to the all-trans configuration. This introduces a succession of unstable intermediates—pre-lumirhodopsin, lumirhodopsin, metarhodopsin —in which all-trans retinal is still attached to the chromophoric site on opsin. Finally, retinal is hydrolyzed from opsin. The present experiments show that metarhodopsin exists in two tautomeric forms, metarhodopsins I and II, with λ_max 478 and 380 mµ. Metarhodopsin I appears first, then enters into equilibrium with metarhodopsin II. In this equilibrium, the proportion of metarhodopsin II is favored by higher temperature or pH, neutral salts, and glycerol. The change from metarhodopsin I to II involves the binding of a proton by a group with pK 6.4 (imidazole?), and a large increase of entropy. Metarhodopsin II has been confused earlier with the final mixture of all-trans retinal and opsin (λ_max 387 mµ), which it resembles in spectrum. These two products are, however, readily distinguished experimentally.

ISOLATION OF MUTANTS AFFECTING TRYPTOPHANASE PRODUCTION IN ESCHERICHIA COLI

Gartner, Theodore K. (University of California, Davis), and Monica Riley. Isolation of mutants affecting tryptophanase production in Escherichia coli. J. Bacteriol. 89:313-318. 1965.-Mutants of Escherichia coli K-12 were isolated which appear to have suffered an alteration in the regulation system governing tryptophanase synthesis. A novel selection method was used to isolate tryptophanase mutants from tryptophan synthetase deletion mutants. Mutants were obtained which exhibited the following phenotypes either singly or in combination with others: constitutivity and inducibility at 13 C (wild type is not inducible at 13 C), constitutivity and hyperinducibility at 37 C. Mutation to constitutivity at 13 C seems to require two mutational changes of the wild type. Other mutants, presumably structural gene mutations, were isolated which lack tryptophanase activity under all conditions tested.

BIOGENESIS OF THE N-METHYL GROUP OF PYOCYANINE

L-Methionine-methyl-C14 or L-serine-3-C14 was added in substrate amount to a medium containing D-quinic acid, glycerol, L-alanine, and salts. Pseudomonas aeruginosa was grown on this medium, and the pyocyanine synthesized by the organism was isolated and degraded to give an estimate of radioactivity in the N-methyl carbon atoms. The methyl carbon atoms of methionine added to the medium supplied 66% of the N-methyl carbon atoms of pyocyanine and were not incorporated to any extent into the rest of the pyocyanine molecule. This was true even though this strain of P. aeruginosa did not require an exogenous supply of methionine to synthesize pyocyanine. The addition of unlabelled serine to the medium did not decrease the incorporation of the methyl carbon atoms of methionine into the N-methyl carbon atoms of pyocyanine. The labelled carbon atoms of serine-3-C14 were incorporated to a lesser extent and less specifically into the N-methyl carbon atoms of pyocyanine than were the methyl carbon atoms of methionine.