bluuebunny/crossref_metadata_2025 huggingface dataset:
Fate of Recipient Deoxyribonucleic Acid During Transformation in
Haemophilus influenzae
Authors: Steinhart William L. , Herriott Roger M.
Published: January 2020

During genetic transformation of
Haemophilus influenzae
, segments of the host deoxyribonucleic acid (DNA) corresponding to the integrating donor DNA were degraded and liberated into the medium. This degradation was detected by the release of the radioactive label from host DNA during a time period matching the time of development of maximal linkage between donor and host markers. The host label released above that released from nontransformed, control cultures was equivalent to about 2% of the host genome or 16 × 10
6
daltons of DNA. The released, labeled material was acid-soluble and dialyzable. The label release from control cultures was unaffected at 30 C; at this temperature, the recombination-specific release from transformed cells was suppressed. High molecular weight fragments of host DNA corresponding in size to the donor fragments could not be found free within the cell, weakly bound to other host DNA, or bound to non-integrated donor DNA by a reciprocal cross mechanism.
Unbalanced Growth Death Due to Depletion of Mn
2+
in
Brevibacterium ammoniagenes
Authors: Oka Tetuo , Udagawa Kiyoshi , Kinoshita Shukuo
Published: January 2020

In the microbial conversion of added hypoxanthine to 5′-inosinic acid, Mn
2+
concentration in the growth medium is known to have a profound effect both on the yield of 5′-inosinic acid and the morphology of cells of
Brevibacterium ammoniagenes
. To elucidate the mechanism in which Mn
2+
was concerned with cell morphology and 5′-inosinic acid production, effects of Mn
2+
on the macromolecular synthesis were measured. It was found that Mn
2+
strongly governed deoxyribonucleic acid (DNA) synthesis and that, in the medium lacking Mn
2+
, DNA synthesis was stopped at the level corresponding to one-fourth to one-third that in the medium supplemented with Mn
2+
(100 μg/liter). On the other hand, cellular ribonucleic acid and protein synthesis was quite indifferent to Mn
2+
concentration. Consequently, cells showed so-called “unbalanced growth death” after 10 hr of culture, losing the ability to form colonies while cell mass was increasing. The elongated cells turned into irregular forms (bulbous, club-shaped, etc.) which finally lysed. Two main reaction components in the conversion of hypoxanthine to 5′-inosinic acid, phosphoribosylpyrophosphate and hypoxanthine phosphoribosyltransferase, were liberated into the medium during lysis. The role of Mn
2+
in the synthesis of DNA and the role of the unbalanced growth death in the conversion of hypoxanthine to 5′-inosinic acid are discussed.
In Vivo Regulation of Intermediate Reactions in the Pathway of Tryptophan Biosynthesis in
Neurospora crassa
Authors: Lester Gabriel
Published: January 2020

The in vivo regulation of intermediate reactions in the pathway of tryptophan synthesis in
Neurospora crassa
was examined in a double mutant (
tr-2, tr-3
) which lacks the functions of the first and last enzymes in the pathway from chorismic acid to tryptophan. The double mutant can convert anthranilic acid to indole and indole-3-glycerol, and the production of these indolyl compounds by germinated conidia was used to estimate the activity of the intermediate enzymes in the pathway. Indole-synthesizing activity was maximal in germinated conidia obtained from cultures in which the levels of
l
-tryptophan were growth-limiting; the formation of this activity was markedly repressed when the levels of
l
-tryptophan exceeded those required for maximal growth.
d
-, 5-methyl-
dl
-, and 6-methyl-
dl
-tryptophan were less effective than
l
-tryptophan, and 4-methyl-
dl
-tryptophan, tryptamine, and indole-3-acetic acid were ineffective in repressing the formation of indole-synthesizing activity; anthranilic acid stimulated the formation of indole-synthesizing activity. Preformed indole-synthesizing activity was strongly and specifically inhibited by low levels of
l
-tryptophan; several related compounds were ineffective as inhibitors. These results suggest that, in addition to repression, an end product feedback inhibition mechanism is operative on an intermediate enzyme(s) in tryptophan biosynthesis. The relation of these results to other in vivo and in vitro studies and to general aspects of the regulation of tryptophan biosynthesis in
N. crassa
are discussed.
Paradoxical Effect of Weak Inducers on the
lac
Operon of
Escherichia coli
Authors: Williams Beverly , Paigen Kenneth
Published: January 2020

Previously, we reported the existence of a group of compounds whose function in the regulation of the
lac
operon was “paradoxical” in that they acted as either inducers or repressors depending on the circumstances. We now show that this group of compounds does not repress the
lac
operon by catabolite repression, transient repression, or by preventing the uptake of inducers. A model is presented which shows that “paradoxical” behavior is to be expected if a weak inducer is present at a concentration that is high relative to its binding affinity for the regulatory macromolecule. This model depends on the assumptions that the regulatory macromolecule is an allosteric protein which undergoes a transition between two conformational states and that the rate of enzyme synthesis depends on the fraction of protein molecules in each state. The previous observations on the responses of
lac
regulatory mutants to weak inducers have been extended to a series of such mutants. Weak inducers repress β-galactosidase synthesis in several
i
−
mutants. When this happens, enzyme synthesis can be reinduced by using a strong inducer such as isopropyl-β-
d
-thiogalactoside. These compounds induce operator constitutives and the
i
t
mutant more easily than they induce a wild-type strain.
Superinfection with R Factors by Transduction inEscherichia coliandSalmonella typhimurium
Authors: Watanabe Tsutomu , Sakaizumi Sachiko , Furuse Chizuko
Published: January 2020

Superinfection immunity is found in the conjugal transfer of R factors between twofi+R factors and between twofi−R factors (fi= fertility inhibition), as we reported previously. In contrast, no reduction in the frequencies of transduction of anfi+R factor 222 was caused by the presence offi+R factors in the recipients in transduction systems with phage P1kc inEscherichia coliK-12 and with phage P22 inSalmonella typhimuriumLT-2. The absence of superinfection immunity in transduction may be due to the difference in the route of entry of the R factor. The frequencies of transduction of anfi+R factor were reduced, although slightly, by the presence offi−R factors in the recipients. This reduction is probably due to host-controlled restriction of the enteringfi+R factor by thefi−R factors in the recipients, since transduction of anfi+R factor by the transducing phage propagated on the strain carrying bothfi+andfi−R factors was not reduced by the presence of homologousfi−R factors in the recipients. Thefi+R factor 222, when transduced to the recipient strains carrying other R factors, recombined genetically at high frequencies with these resident R factors, regardless of theirfitype.
Cytology of Spore Formation in
Clostridium perfringens
Authors: Hoeniger Judith F. M. , Stuart Philip F. , Holt Stanley C.
Published: January 2020

The sequential morphological events in spore formation by
Clostridium perfringens
type D were observed in Ellner's medium where 80 to 100% of the cells formed spores. Gross structural changes were studied with the light microscope under phase-contrast, and in fixed cells by the use of both nigrosin and Giemsa preparations. Fine structure was examined with the electron microscope in both thin sections and frozen-etched preparations. During the first 3 hr of incubation, the original rod-shaped cells became ellipsoid to ovoid in shape; by 5 to 6 hr, subterminal spores had developed within these enlarged cells. The fine structural sequence was in most respects identical to that in other
Bacillaceae
, although some stages were illustrated with particular clarity. A unique feature was the development of a convoluted, membranous exosporium which adhered to the outer surface of the two coats and had an unusual fine structure resembling a rectangular array of subunits.
Cytology of Spore Germination in
Clostridium pectinovorum
Authors: Hoeniger Judith F. M. , Headley C. L.
Published: January 2020

The process of spore germination in
Clostridium pectinovorum
has been followed by phase-contrast and electron microscopy. Unlike most other
Bacillaceae
, germination of this species takes place within the sporangium. Under phase-contrast, the spore darkens and swells slightly, and then the vegetative rod slips out through the end opposite the collar-like extension of the sporangium. In thin sections, a spore from an early stage in germination consists of a central protoplast, core membrane, germ cell wall, cortex, and two coats. Within a short period, the cortex disintegrates and the young cell develops. It possesses a large fibrillar nucleoplasm and several mesosomes. Subsequently, the young cell elongates, becomes somewhat deformed, and then emerges through a narrow aperture in the inflexible coats of the spore, finally rupturing the sporangium. Free vegetative cells of
C. pectinovorum
resemble in their structure other gram-positive rods.
Effects of Penicillin and Glycine on Cell Wall Glycopeptides of the Two Varieties of
Vibrio fetus
Authors: Fung P. H. , Winter A. J.
Published: January 2020

Actively growing strains of
Vibrio fetus
venerealis and
V. fetus
intestinalis, none of which produced penicillinase, were treated with inhibitory levels of penicillin or glycine, primarily to gain insight into the differential sensitivities of the two varieties to both of these compounds. Treatments induced the accumulation of uridine nucleotide glycopeptide precursors which contained amino sugars and amino acids in various molar ratios. Penicillin-induced nucleotides all contained muramic acid and sometimes glucosamine; they generally contained alanine, glutamic acid, diaminopimelic acid, and glycine. Approximately equimolar ratios of these components were observed in some compounds, but ratios varied considerably in others. Glycine-induced nucleotides contained muramic acid and, in some instances, glucosamine. Amino acids were detected only infrequently and usually in low molar ratios. The data suggest that penicillinase production, differences in the chemical composition of glycopeptide, and variations in modes of action of penicillin and glycine cannot individually account for the differential sensitivities of venereal and intestinal strains of
V. fetus
to these substances.
Effect of Lysogeny on Serum Sensitivity
Authors: Muschel Louis H. , Ahl Lissa A. , Baron L. S.
Published: January 2020

WhenEscherichia coliK-12 was infected with λ phage and mutants of λ characterized by the production of temperature-sensitive repressors, the lysogenic bacteria were significantly more resistant to normal serum than the uninfected organisms. Infection ofE. coliK-12 with a lambdoid phage, φ80, whose prophage attachment site is different from that of λ, did not result in a detectable change in serum resistance. Similarly, infection with certainPseudomonasandShigellaphages caused no detectable differences in serum resistance. Finally, the well-known conversion of theSalmonella anatumserotype toS. newingtonby E15phage indicated that, despite the relatively greater roughness ofS. anatum, S. newingtonwas more sensitive to normal serum thanS. anatum. Thus, the effects of lysogeny on the sensitivity of bacteria to the bactericidal action of serum mediated by the complement system may be quite variable.
Effects of Chelates in Chemotherapy of Experimental Gas-Gangrene Toxemia
Authors: Lynch Kenneth L. , Moskowitz Merwin
Published: January 2020

The relative ability of the calcium chelates of calcium disodium ethylenediaminetetraacetate (EDTA) and calcium trisodium ethylenetriaminepentaacetate (DTPA) to protect mice against lethal doses of
Clostridium perfringens
α-toxin was investigated. Their protective ability was assayed by the increase in survival time of mice which had been given large doses of toxin, and by determining the median protective dose of chelate that would protect mice against toxin at a minimum lethal dose of two. In both assay procedures, intraperitoneal, intravenous, and intracutaneous injections of toxin were utilized, and with each toxin injection route the protective ability of the chelate was determined with the three routes of injection. DTPA was 10 to 20 times more effective than EDTA with both types of assay procedure and with all injection routes. DTPA may be superior to EDTA as a protective agent not only because it binds zinc to a greater extent, but also because of its greater retention in the body and its ability to gain entrance into cells. It appears that DTPA may be of value as a therapeutic agent in gas-gangrene.
Complement-inactivating Proteinase(s) fromClostridium histolyticum
Authors: Goldlust Marvin B. , Luzzati Alma , Levine Lawrence
Published: January 2020

A proteinase fraction inhibiting the hemolytic activity of guinea pig complement was obtained from supernatant fluids ofClostridium histolyticumcultures and purified 150- to 350-fold by ammonium sulfate precipitation, Sephadex G-75 gel filtration, and diethylaminoethyl cellulose chromatography. An assay was developed based on the inactivation of hemolytic complement. Partially purified anticomplementary preparations were active against casein and were capable of “solubilizing”Escherichia coliendotoxin. Two components were found by differential heat inactivation, with complement and casein as substrates, but only one of these components was active against endotoxin. The more heat-stable activity, showing 50% inactivation at about 47 C, was characterized as topH and ionic strength optima and sensitivity to reagents such as cysteine, β-mercaptoethanol, ethylenediaminetetraacetate, and heavy metals.
Biosynthesis of Branched-Chain Amino Acids in Yeast: Correlation of Biochemical Blocks and Genetic Lesions in Leucine Auxotrophs
Authors: Satyanarayana T. , Umbarger H. E. , Lindegren Gertrude
Published: January 2020

The three enzymatic steps in the conversion of α-ketoisovalerate to α-ketoisocaproate were examined in wild-type and in leucine auxotrophic stocks of yeast. Procedures for the reliable assay of each of the enzymatic steps in crude extracts were devised. Crude extracts of the prototrophic haploid stock catalyzed all three enzymatic steps. Examination of a series of leucine auxotrophs permitted a correlation between the three enzymatic steps and the genetic lesions affecting 10 different loci. This examination revealed that a single locus (
le
-6) affected primarily α-isopropylmalate synthetase, the first step in the pathway. Lesions in six loci (
le
-1,
le
-4,
le
-5,
le
-7,
le
-8, and
le
-10) lead primarily to a deficiency in the activity of the second enzyme in the pathway, α-isopropylmalate isomerase. Stocks with lesions in three loci (
le
-2,
le
-3, and
le
-9) were primarily blocked in the third step of the pathway, catalyzed by β-isopropylmalate dehydrogenase. The results with the mutants provide strong evidence that the pathway for leucine biosynthesis proposed by Strassman and his colleagues is the sole significant pathway in yeast.
Biosynthesis of Branched-Chain Amino Acids in Yeast: Regulation of Leucine Biosynthesis in Prototrophic and Leucine Auxotrophic Strains
Authors: Satyanarayana T. , Umbarger H. E. , Lindegren Gertrude
Published: January 2020

The first enzyme in the biosynthesis of leucine in yeast, α-isopropylmalate synthetase, is inhibited by
l
-leucine. In a mutant resistant to the analogue 5′,5′,5′-trifluoroleucine, the enzyme is markedly resistant to inhibition by
l
-leucine. Growth ing the presence of exogenous
l
-leucine results in repression of the second and third enzymes of the pathway. The first enzyme is not repressed unless both
l
-leucine and
l
-threonine are supplied in the medium. Comparison of levels of the remaining two enzymes in leucine auxotrophs grown under conditions of leucine excess and leucine limitation reveals deviations from the wild-type derepression pattern in some mutants. In some, repression of the synthetase by leucine alone was observed. In others, the repressibility of the dehydrogenase was lost. It is unlikely that these deviations were due to the same primary mutational event that caused leucine auxotrophy. No mutants were found in which an altered gene was recognized to be clearly responsible for the level of the leucine-forming enzymes.
Stability of the Nucleic Acids of L Cells After Infection with the Meningopneumonitis Agent
Authors: Lin Hsiu-San
Published: January 2020

The stability of host nucleic acids in L cells infected with
Chlamydia psittaci
(strain meningopneumonitis) was studied. The L cells were prelabeled with either
32
P-orthophosphate,
3
H-uridine, or
3
H-thymidine. After infection, the redistribution of each label among the different fractions of host and parasite was quantitatively determined and compared. There were no signs of accelerated degradation of host nucleic acid as the consequence of meningopneumonitis infection. Comparison of the specific activities of the meningopneumonitis nucleic acids with that of the acid-soluble fraction of host cell cytoplasm suggested that the major source of precursors for parasite nucleic acid synthesis was the common cytoplasmic pool of the infected host cell.
Macromolecular Synthesis and Thymineless Death in
Mycoplasma laidlawii
B
Authors: Smith Douglas W. , Hanawalt Philip C.
Published: January 2020

The relationships between macromolecular synthesis and viability have been studied in the pleuropneumonia-like organism
Mycoplasma laidlawii
B adapted to a semidefined grwoth medium. This organism exhibited an absolute growth requirement for the nucleosides uridine and thymidine, a partial requirement for guanosine and deoxyguanosine, but no requirement for adenosine, deoxyadenosine, cytosine, and deoxycytosine. Cytosine and deoxycytosine partially satisfied the requirement for uridine. Loss in viability resulted from thymidine deprivation, but not from a deficiency in other growth requirements. This phenomenon of thymineless death in a mycoplasma is similar in many respects to that reported in other bacterial systems. Chloramphenicol specifically inhibited protein synthesis and allowed deoxyribonucleic acid synthesis to proceed to only about 40% of that normally produced per generation period, while causing less inhibition of ribonucleic acid synthesis. Protein synthesis inhibition permitted thymineless death to a survival level of less than 0.5%, but ribonucleic acid synthesis inhibition resulted in a higher (10%) survival level. These results are consistent with previously noted aspects of thymineless death in
Escherichia coli
strains, which suggest that thymineless death is coupled to ribonucleic acid synthesis.
Ultrastructure of Mitochondria and Crystal-containing Bodies in Mature Ballistospores of the Fungus
Basidiobolus ranarum
as Revealed by Freeze-etching
Authors: Bauer Heinz , Tanaka Kenji
Published: January 2020

By using the freeze-etch technique, a regular pattern on both sides of the outer mitochondrial membrane can be demonstrated in mature spores of
Basidiobolus ranarum
. Bands consisting of 5 to 10 parallel ridges, each of which is 20 nm wide, envelop the outer as well as the inner side of this membrane. Hexagonal crystals, probably representing stored protein, are enclosed in special bodies with a very smooth surrounding unit membrane. The crystals are formed by parallel rods which consist of globular subunits, 6.5 to 7.0 nm wide.
Respiration-enhancing Effect of Tuberculin on Splenic Cells of Hypersensitive Guinea Pigs
Authors: Kochan Ivan , Khan Amanullah
Published: January 2020

Oxygen utilization in splenic cells of normal and BCG-sensitized guinea pigs was measured in a Warburg respirometer in the absence and in the presence of Old Tuberculin (OT). In the absence of OT, normal and sensitive cells respired at the same rate; in the presence of OT, normal cell respiration remained unchanged, whereas the respiration of sensitive cells increased significantly. This enhancement of oxygen utilization in sensitive cells was induced with OT but not with Purified Protein Derivative and it was most pronounced during the first hour of the interaction between the cells and the antigen. When normal splenic cells were treated with an extract of hypersensitive cells, their respiration was enhanced in the presence of OT. Oxygen utilization in cells of desensitized animals did not differ from that in cells of normal animals. The absence of reactivity to OT in splenic cells and in the skin of desensitized guinea pigs suggested that both phenomena are expressions of antigen-induced biological changes in cells of animals with delayed hypersensitivity.
Immunizing Capacity of Viable and Killed Attenuated Mycobacterial Cells Against Experimental Tuberculous Infection
Authors: Youmans Guy P. , Youmans Anne S.
Published: January 2020

The relationship of the dose of vaccine to the immune response was determined in CF-1 mice vaccinated intraperitoneally with viable cells of the attenuated H37Ra strain ofMycobacterium tuberculosisand in mice vaccinated with cells of the same strain killed by autoclaving at 121 C for 15 min. The results showed, in terms of increased resistance to tuberculous infection, that the immune response with both living and killed cells was dependent upon the dose of vaccine, whereas only the living cells were dependent upon the time of challenge after vaccination. The dose response curves show dramatically that viable cells, which do not multiply in vivo, are several hundred times more effective immunizing agents against tuberculous infection than are autoclaved cells. Viable 2-week-old H37Ra cells were far more immunogenic than viable 4-week-old cells. Autoclaved 2-week-old cells, however, were no more immunogenic than autoclaved 4-week-old cells. H37Ra cells killed by boiling (98 C), exposure to 65 C for 30 min, treating with 2% phenol, or by being dried with acetone also lost most of their capacity to immunize mice. The effect of adjuvant on the immune response of mice to tuberculous infection was tested by incorporating both viable and autoclaved cells in Freund's incomplete adjuvant. We found that this vehicle had little or no effect on the immunizing capacity of either viable or heat-killed mycobacterial cells. The relationship of all the findings to the specificity of the immune response to tuberculosis is discussed.
Specificity of Acquired Resistance Produced by Immunization withListeria monocytogenesand Listeria Fractions
Authors: Coppel Suzanne , Youmans Guy P.
Published: January 2020

Mice were immunized with 1.0 mg of an attenuated strain ofListeria monocytogenesto determine the period of protection afforded by this strain when the mice were challenged intravenously with 5 MLD of listeria. Protection appeared 2 days after immunization and was still apparent 4 weeks after immunization. If the challenge dose was decreased to 1 MLD, protection was apparent at 10 weeks. Mice immunized with a comparable dose of mycobacterial cells and challenged intravenously with 1 MLD of listeria showed no protection at 10 weeks. The magnitude of the immune response to listeria challenge was not increased in mice immunized with the same virulent strain as that used for challenge. It was also found that resistance to listeria challenge appeared early after listeria immunization if the immunizing dose was large. As the immunizing dose was decreased and the challenge dose increased, resistance appeared later. Listeria killed by heat or ultraviolet irradiation, living but nonmultiplying streptomycin-dependent listeria, or listeria ribosomal fraction gave no protection against listeria challenge. The magnitude of the immune responses after listeria immunization to listeria challenge and to mycobacteria challenge were compared. It was found that protection after listeria challenge was of longer duration. In addition, a 100-fold larger vaccinating dose was required to give comparable protection against tuberculous infection.
Specificity of the Anamnestic Response Produced byListeria monocytogenesorMycobacterium tuberculosisto Challenge WithListeria monocytogenes
Authors: Coppel Suzanne , Youmans Guy P.
Published: January 2020

When mice immunized withListeria monocytogeneswere given a second injection of listeria, they showed an anamnestic immune response to intravenous challenge with listeria, as measured by enumeration of the viable infecting organisms in the spleens of the infected animals. This response was independent of the effects of the challenge dose. When mice immunized with living or heat-killed attenuated mycobacterial cells were boosted with living H37Ra, there was also an accelerated response to listeria challenge. The response was greater in the mice given the primary immunization with living cells than in those immunized with heat-killed cells. The response to listeria challenge in mice immunized and boosted with mycobacteria was of less magnitude than that in the mice immunized and boosted with listeria. Growth of listeria in the mice immunized and boosted with mycobacteria was retarded only during the first 2 days of the infection, whereas the infecting listeria in mice immunized and boosted with listeria were permanently inactivated. Mice immunized with mycobacterial ribosomal fraction and restimulated with living mycobacterial cells showed no accelerated response to listeria challenge. It is evident from these results that resistance to these organisms is specifically evoked, but that once evoked it is not completely nonspecific in action. Also, the resistance produced by the mycobacterial ribosomal fraction to challenge with mycobacteria is completely specific in action. Therefore, it has been shown that there are two mechanisms involved in acquired immunity to facultative, intracellular parasites. One is nonspecific and mediated by activated macrophages. The other is specific and mediated by a mechanism as yet unknown.
Allergenicity of Mycobacterial Ribosomal and Ribonucleic Acid Preparations in Mice and Guinea Pigs
Authors: Youmans Guy P. , Youmans Anne S.
Published: January 2020

Guinea pigs were injected subcutaneously with mycobacterial ribosomal fraction incorporated in Freund's incomplete adjuvant and tested 6 and 12 weeks later by the intradermal injection of 0.5 μg (25 TU) of Purified Protein Derivative. No evidence of delayed-type hypersensitivity could be detected in these animals, although large necrotic reactions were obtained in guinea pigs sensitized with living, attenuated mycobacterial cells. Mice also were vaccinated by the intraperitoneal injection of mycobacterial ribosomal fraction or ribonucleic acid (RNA) and tested for sensitivity to tuberculin at various subsequent times. No evidence of true tuberculin hypersensitivity could be detected at any time, although what appeared to be small Arthus type reactions were seen in mice given the largest vaccinating doses. Attempts to recall tuberculin sensitivity in vaccinated mice by the intravenous injection, 4 weeks after vaccination of living cells, of either the virulent or attenuated mycobacterial strains were unsuccessful. Instead, when the virulent cells were injected, a suppression of footpad reactivity was noted in animals made sensitive to tuberculin by the previous intraperitoneal injection of viable attenuated mycobacterial cells. Both guinea pigs and mice, vaccinated as described above, were also skin tested or footpad tested, respectively, with 2 μg of the ribosomal fraction or RNA used for vaccination. No evidence of true tuberculin hypersensitivity could be obtained; instead, in guinea pig skin very small dermonecrotic areas were noted, and in mice swelling and redness of the footpad occurred to an equal extent in both vaccinated and nonvaccinated mice. The possible role of tuberculin hypersensitivity in acquired immunity to tuberculosis is discussed, and the conclusion is reached that its part, if any, is minor.
Metabolism of α-Aminoisobutyric Acid by Soil Bacteria
Authors: Dempsey Walter B.
Published: January 2020

Eleven different bacteria, isolated by enrichment procedures on α-aminoisobutyric (AIB) as sole fixed nitrogen source, were examined for the mechanism by which they attacked the amino acid. All eleven organisms, including one which grew well on isopropylamine, converted AIB to acetone and CO
2
and showed an absolute dependence upon pyruvate for this reaction. No organism isolated degraded AIB to isopropylamine as the primary reaction. The data suggested that the usual mode of attack upon this amino acid is by an overall reaction comprised of two half reactions, one a decarboxylation-dependent transamination and the other a normal exchange transamination.
Role of
lac
Genes in Induction of β-Galactosidase Synthesis by Galactose
Authors: Llanes Barbara , McFall Elizabeth
Published: January 2020

Strain BL1003, a
lacO
mutant, synthesizes β-galactosidase constitutively at a low rate. The enzyme is further inducible by
d
-galactose to the same differential rate as is seen in the presence of an optimal concentration of thiomethylgalactoside.
lacY
Mutants derived from strain BL1003 are not inducible by galactose, although they synthesize β-galactosidase at the low constitutive rate characteristic of the parent. Galactose is a weak inducer of β-galactosidase synthesis in wild-type
Escherichia coli
K-12, but it is more effective when the wild type has been preinduced with isopropyl-β-
d
-thiogalactoside. Nevertheless, the rise in the differential rate of synthesis in response to galactose in a preinduced wild-type culture is much lower than in strain BL1003. Thus, two factors are involved in the induction of strain BL1003 by galactose: the mutant operator and the constitutive permease. The operator has an altered sensitivity to the
i
product-galactose complex. The low constitutive level of permease enabled the cells, at the high concentrations of galactose used (5 × 10
−2
m
), to maintain a sufficient internal concentration for further induction.
Comparison of the Catalytic and Immunological Properties of β-Glucosidases from Three Strains of
Saccharomyces lactis
Authors: Marchin George L. , Duerksen Jacob D.
Published: January 2020

β-Glucosidase from
Saccharomyces lactis
strains Y-123 (B
h
), Y-14 (B
m
), and Y-1057A (B
1
) was partially purified. The
p
H optima, Michaelis constants, and activation energies were determined for the hydrolysis of
p
-nitro-phenyl-β-
d
-glucoside by each of the enzymes. Differences among these constants were not enough to account for the low specific activity of β-glucosidase in strains Y-14 and Y-1057A. Enzyme-inhibitor constants were measured for a series of alkyl and aryl glucosides. In general, the three enzymes are arylglucosidases. Tris(hydroxymethyl)-aminomethane inhibited all three enzymes in an uncompetitive fashion. The inhibition was antagonized by Mg
++
. An antiserum was prepared to the highly purified (200-fold) β-glucosidase from strain Y-123. The nature and degree of cross-reaction between the three β-glucosidases was investigated by double diffusion in agar and neutralization tests. Spur formation in the immunodiffusion tests and similar equivalence points in the neutralization tests indicated a strong degree of cross-reaction between the three enzymes. The ratio of enzyme activity to antigenicity was used to compare the relative molecular activity of β-glucosidase in the three strains. Each strain produced the same amount of β-glucosidase per milligram of cell protein. The results are consistent either with a lower turnover number for the β-glucosidase in strains Y-14 and Y-1057A or with the production of β-glucosidase with a “normal” turnover number and enough cross-reacting material to effectively reduce the specific activity to the observed levels.
Genetic Location of Certain Mutations Conferring Recombination Deficiency in
Escherichia coli
Authors: Willetts Neil S. , Clark Alvin J. , Low Brooks
Published: January 2020

Four mutations conferring recombination deficiency (
recA1, recA13, rec-12
, and
rec-65
) have been cotransduced with
cysC
and
pheA
; consequently they lie between 53 and 50 on the standard genetic map of
Escherichia coli
. The four mutations show different degrees of apparent dominance in transient
rec
+
/
rec
−
zygotes, and the degree of apparent dominance of a particular mutation was shown to be a characteristic of that mutation, not a reflection of other genetic differences in the original
rec
mutant strain. All four mutations map at similar distances from
cysC
and
pheA
and, despite the different degrees of apparent dominance, all may lie in the
recA
gene.
Genetic Analysis of Carbohydrate Transport-deficient Mutants of
Salmonella typhimurium
Authors: Levinthal Mark , Simoni Robert D.
Published: January 2020

Mutants (
car
) isolated from
Salmonella typhimurium
were unable to utilize or ferment the following carbohydrates (all
d
-configuration): glucose, fructose, mannose,
N
-acetylglucosamine, sorbitol, mannitol, maltose, melibiose, and glycerol. The mutants did utilize galactose, glucose 6-phosphate, gluconic acid, glucuronic acid, pyruvate, and
l
-lactate. Biochemical analysis showed that there were two classes of mutants, each lacking one component of a phosphotransferase system.
CarA
mutants were deficient in enzyme I;
carB
lacked the phosphate carrier protein, HPr. Mapping experiments showed that the
carA
gene was located near
pro
; the
carB
gene mapped near
purC
.
Effects of Temperature on Composition and Cell Volume of
Candida utilis
Authors: Brown C. M. , Rose A. H.
Published: January 2020

Candida utilis
NCYC 321 was grown in steady-state culture in a chemostat under glucose limitation or NH
4
+
limitation at temperatures of 30, 25, 20, and 15 C and at dilution rates (equal to growth rates) in the range of 0.35 to 0.05 hr
−1
. Deoxyribonucleic acid contents of cells grown under the various conditions remained approximately constant, but the contents of several other cell components varied. Over the range of 30 to 15 C, the greatest differences were in the ribonucleic acid (RNA) and protein contents of cells grown under NH
4
+
limitation, which increased as the temperature was decreased. The contents of other components, particularly adenosine triphosphate in cells grown under glucose limitation, varied more when the cells were grown at different rates at a fixed temperature. Cells grown at a fixed rate under NH
4
+
limitation increased in volume as the temperature was decreased below 30 C. The increase in volume was closely correlated with increases in the proportions of RNA and protein in the dry weight of cells. Cells grown under glucose limitation showed much smaller increases in volume; these increases were poorly correlated with the increased RNA content and hardly at all with the increased protein content. Increases in volume with a decrease in growth temperature from 30 to 20 C were also demonstrated in cells grown under phosphate limitation and to a much smaller extent in cells grown under glycerol limitation. The increased RNA synthesized at low temperatures by cells grown under NH
4
+
limitation was found almost exclusively in the 40,000 ×
g
supernatant fluid, but only about 40% of it sedimented at 100,000 ×
g
. Cells grown at a fixed rate under NH
4
+
limitation synthesized less total carbohydrate when the temperature was decreased from 30 to 15 C. This decrease was mainly in the trichloroacetic acid-soluble fraction (probably trehalose) and in the intracellular hot alkali-soluble glucan (probably glycogen). Cells grown at a fixed rate under glucose limitation showed a small increase in carbohydrate content as the temperature was decreased from 30 to 15 C.
Ribosomal Ribonucleic Acid Maturation During Bacterial Spore Germination
Authors: Bleyman Michael , Woese Carl
Published: January 2020

All the ribosomal ribonucleic acid made during the early stages of germination of spores of
Bacillus subtilis
is of the “precursor” type, i.e., that type appearing in the incomplete forms of the ribosome. Shortly before the onset of deoxyribonucleic acid synthesis in germination, this precursor ribonucleic acid changed to the mature ribosomal ribonucleic acid characteristic of the 30
S
and 50
S
ribosomal subunits.
Amino Acid Transport in
Pseudomonas aeruginosa
Authors: Kay W. W. , Gronlund Audrey F.
Published: January 2020

Properties of the transport systems for amino acids in
Pseudomonas aeruginosa
were investigated. Exogenous
14
C-labeled amino acids were shown to equilibrate with the internal native amino acid pool prior to incorporation into protein. When added at low external concentrations, the majority of the amino acids examined entered the protein of the cell unaltered. The rates of amino acid transport, established at low concentrations with 18 commonly occurring amino acids, varied as much as 40-fold. The transport process became saturated at high external amino acid concentrations, was temperature-sensitive, and was inhibited by sodium azide and iodoacetamide. Intracellular to extracellular amino acid ratios of 100- to 300-fold were maintained during exponential growth of the population in a glucose minimal medium. When the medium became depleted of glucose, neither extracellular nor intracellular amino acids could be detected.
Dependence of Protease Secretion by
Streptococcus faecalis
var.
liquefaciens
on Arginine and Its Possible Relation to Site of Synthesis
Authors: Casas Ivan A. , Zimmerman Leonard N.
Published: January 2020

Washed cells of
Streptococcus faecalis
var.
liquefaciens
, when harvested from media that supported protease biosynthesis, continued to release this extracellular enzyme in phosphate buffer. The addition of ethylenediaminetetraacetic acid (EDTA) halted the secretion. If zinc ions were added to the EDTA-treated cells before 45 to 60 min had elapsed, a fraction of the anticipated enzyme activity was observed. After 60 min, arginine and phosphate, in addition to zinc, were necessary for the demonstration of proteolytic activity. The enzyme that was released was newly formed, because chloramphenicol, puromycin, or actinomycin D prevented its appearance. Energy for this synthetic reaction was obtained, apparently, from arginine; lactose could not be substituted for arginine. This last point is interpreted to mean that extracellular protease biosynthesis occurs in a localized area or cellular compartment into which the adenosine triphosphate derived from the fermentation of lactose cannot diffuse. No evidence was found for a protease zymogen, although this possibility is not completely precluded.
Amino Acid Regulation of Messenger Ribonucleic Acid Synthesis in T4-infected
Escherichia coli
Authors: Friesen J. D.
Published: January 2020

The effect of amino acid starvation on the synthesis of T4 messenger ribonucleic acid (mRNA) was studied by measuring the uptake of labeled precursors into
Escherichia coli
cells which were infected prior to amino acid starvation. The results indicated that the rate of uptake of labeled uracil and adenine into T4 mRNA was reduced by approximately 50% when amino acids were withheld from stringent K-12 strains, but not when they were withheld from a stringent strain B or a relaxed strain K-12. Chloramphenicol reversed the inhibition of precursor uptake resulting from amino acid starvation in the RC
str
K-12 strain. Pulse-labeling experiments reinforced these observations. Pulse-decay experiments in conjunction with actinomycin D indicated that the observed pattern of precursor uptake was probably
not
due to differences in mRNA decay rate. It is concluded that if amino acids exert any direct effect on the synthesis of T4 mRNA such an effect is much smaller than that observed for bulk RNA synthesis in the uninfected cell. These experiments also indicated that actual translation of the genetic message is not necessary for its transcription.
β-Cyanoalanine Formation by
Chromobacterium violaceum
Authors: Brysk Miriam M. , Corpe W. A. , Hankes L. V.
Published: January 2020

Nonproliferating cells of
Chromobacterium violaceum
incubated with glycine, methionine, and succinate as substrates accumulated β-cyanoalanine in the culture fluid. Tracer experiments showed that carbons-2, -3, and -4 of β-cyanoalanine are derived from the 2-carbon of glycine. When methionine-methyl-
14
C, succinate-
1,4
-
14
C, or succinate-
2,3
-
14
C
was used as substrate, β-cyanoalanine did not become labeled. If K
14
CN and serine were used as substrates, the cyano group of β-cyanoalanine was labeled. Radioactive β-cyanoalanine, labeled in the 3-carbon, was formed when glycine and H
14
CHO were used as substrates.
14
C-formic acid did not replace formaldehyde. Asparagine also accumulated in the incubated mixture and was found to be labeled in the amide carbon. Incubation of cells with β-cyanoalanine-
4
-
14
C
produced labeled aspartic acid in cell hydrolysates.
Alteration in Bacterial Morphology by Optochin and Quinine Hydrochlorides
Authors: Kreger Arnold S. , Swartzendruber D. C. , Olsen R. H.
Published: January 2020

Incubation of washed bacterial and ribosomal suspensions with optochin or quinine hydrochloride caused an increase in the turbidity of the suspensions and the appearance of electron-dense cytoplasmic aggregates in the treated cells. These effects were more pronounced with optochin hydrochloride than with quinine hydrochloride, and they did not correlate with the relative sensitivities of different bacteria to growth inhibition by optochin or quinine.
Electron Microscopy and Viability of Lysostaphin-induced Staphylococcal Spheroplasts, Protoplast-like Bodies, and Protoplasts
Authors: Schuhardt V. T. , Huber T. W. , Pope Leodocia M.
Published: January 2020

The cell walls of a selected isolate of
Staphylococcus aureus
FDA 209P were observed undergoing progressive disintegration when exposed to lysostaphin (1 unit/ml) in 24% NaCl solution. Electron micrographs of ultrathin sections of test cells after exposure to lysostaphin for 2 min showed only superficial evidence of lytic damage. However, an average of 89% of these cells were osmotically fragile, and 21% were damaged beyond their capacity to regenerate cell walls and to grow as normal staphylococci. The 68% (average) of the osmotically fragile cells which retained the capacity to revert to normal staphylococci were designated spheroplasts. Neither perforations of the cell walls nor separation of the cell walls from the plasma membranes were observed in the micrographs of these 2-min spheroplasts. Thus, it appears that the osmotic fragility of these and possibly all lysostaphin-induced staphylococcal spheroplasts results from the hydrolysis of a critical number of the pentapeptide cross-linkages of the murein of the cell wall. Electron micrographs of cells exposed to lysostaphin for 5 to 10 min showed perforations and more extensive damage, including the separation of walls from the plasma membranes and the disintegration of large sections of the walls. Smaller numbers of spheroplasts (21 and 8%) were recovered from these 5- and 10-min preparations; those recovered probably represent cells which were attacked more slowly than the majority by the lytic enzyme. The nonrevertible, osmotically fragile cells that retained segments of cell wall were designated protoplast-like bodies. After 20-min exposure to lysostaphin, all of the cell wall was digested away from most of the cells, and true staphylococcal protoplasts were produced. These lysostaphin-induced, osmotically fragile forms appear to have different osmotic properties from the staphylococcal “protoplasts” reported by other investigators and should serve as the basis for a variety of fundamental investigations.
Transformation in Quasi Spheroplasts of
Bacillus subtilis
Authors: Tichy Pavel , Landman Otto E.
Published: January 2020

Recently developed differential plating media permit the distinction of four cell types in incompletely protoplasted populations: intact, osmotically insensitive bacilli; osmotically sensitive rods; spheres with adherent wall residues, called quasi spheroplasts; and protoplasts. Such population mixtures were washed free of lysozyme, and then transforming deoxyribonucleic acid (DNA) was added. Transformation was nil in the protoplasts, very low in the residual osmotically insensitive bacilli, and markedly enhanced in both osmotically sensitive rods and quasi spheroplasts. Transformation in the latter two population fractions was reduced, respectively, by about 60% and about 80% by deoxyribonuclease treatment. DNA adhering to the quasi spheroplasts transforms these cells only if they are permitted to resume wall synthesis; when the same cells are plated on a medium where they shed the residual wall and form L colonies, no transformant L colonies are recovered. It is inferred that far-reaching or complete protoplasting blocks all entry of transforming DNA into the cell interior. This may be owing to eversion of mesosomes. Evidence that intact mesosomes may be required for DNA entry is provided by the finding that the recovery of transformants in the intact cell system is sharply reduced on plating media containing 25% gelatin. On such media, cells expel their mesosomes and 75% of them do not re-form any. Our own data and a survey of published results suggest the generalization that partial depolymerization of the cell wall by lysozyme may enhance competence, whereas its complete removal abolishes it.
Mutant of
Escherichia coli
Exhibiting a Cold-sensitive Phenotype for Growth on Lactose
Authors: Squires Catherine K. , Ingraham John L.
Published: January 2020

As part of a study on the effect of low temperature on cellular regulatory processes, a class of lactose-negative mutants of
Escherichia coli
K-12 was isolated which could use lactose as a sole carbon and energy source at 37 C, but which could not use this sugar at 20 C. The lactose operon of the mutants functioned normally at 20 C. Galactose exhibited a strong inhibitory effect on growth, especially at 20 C. Growth of the mutants on glycerol was stopped at 20 C and slowed considerably at 37 C if galactose was added to the medium. Making the mutants galactose-positive eliminated the cold sensitivity of lactose utilization. One mutant was shown to be galactose-1-phosphate uridyl transferase-negative, galactose-kinase heat-sensitive, and uridine diphosphate-galactose-4-epimerase-positive. It is postulated that the mutant is able to phosphorylate galactose at 20 C (if only at a very low rate), but lacking transferase it is poisoned by the accumulation of galactose-1-phosphate. At 37 C, galactokinase is nonfunctional and the mutant grows on the glucose moiety of lactose.
Inhibition ofShigella flexneriby the Normal Intestinal Flora II. Mechanisms of Inhibition by Coliform Organisms
Authors: Hentges David J.
Published: January 2020

Of 15 strains of coliform bacteria, all isolated from human feces, 14 inhibited the growth ofShigella flexneriin mixed culture. In every case, when inhibition occurred, exponential growth ofShigellawas interrupted in the mixed culture and the organisms entered into either a stationary or a death phase. None of the test coliform strains produced colicines active againstShigella. An analysis of mixed-culture environments at the timeShigellainhibition occurred revealed that the inhibition was not due to nutrient depletion nor to the development of adversepH or oxidation-reduction potentials in themselves. In mixed cultures, the coliform strains produced formic and acetic acids in concentrations that inhibitedShigellagrowth. With one exception, the coliform strains also greatly reduced the culture medium. In average concentrations produced, the formic and acetic acids exerted a bactericidal effect onShigellaunder the reduced conditions found in mixed cultures. The acids were only moderately toxic for the coliform strains under the same conditions. Results indicate that volatile acid production and concomitant reduction of the medium are the mechanisms by which coliform bacteria inhibitShigellagrowth in mixed cultures.