Maximal shelf life was determined and microbial flora were compared for irradiated (0.1 and 0.2 Mrad) and nonirradiated yellow perch fillets stored at 1 C. Shelf life was estimated by organoleptic determinations. Microbiological studies included determination of the effects of irradiation on the total aerobic microbial population, lag phase, and rate of growth. Genera of organisms isolated from fillets through the course of microbial spoilage were identified, and the proteolytic activity of the organisms was determined. Plate counts for fish prior to irradiation showed the presence of approximately 10(6) organisms per g of sample. Irradiation to 0.1 and 0.2 Mrad produced 1.4 and 3 logarithm reductions of the initial count, respectively. Irradiation to 0.1 and 0.2 Mrad approximately doubled the product's shelf life. Organisms initially isolated from the nonirradiated fillets, in order of decreasing number, consisted of Flavobacterium, Micrococcus-Sarcina, Achromobacter-Alcaligenes-Mima, Pseudomonas, Microbacterium, Vibrio, Bacillus, Corynebacterium, Lactobacillus, Brevibacterium, and Aeromonas. By the 6th and 9th days of fillet storage, Pseudomonas and the Achromobacter group were the predominant organisms. All members of the genus Flavobacterium, but not all members of the genus Pseudomonas, were proteolytically active on raw fish juice-agar and skim milk-agar media. The Achromobacter group was found to be nonproteolytic on both media. Residual flora of fillets irradiated to 0.1 and 0.2 Mrad consisted of the Achromobacter group, Lactobacillus, Micrococcus-Sarcina, and Bacillus. Their sequence in predominance, however, varied with dose level. Not all proteolytic bacteria in the fillets were eliminated by 0.1 and 0.2 Mrad; proteolytic Micrococcus-Sarcina survived these treatments.
The microfloral changes of irradiated petrale sole fillets during anaerobic (vacuum-packed in cans) refrigerated storage was determined by the identification of 1,260 microbial isolates to the generic level. The samples were irradiated at 0.0, 0.1, 0.2, 0.3, and 0.4 Mrad from a cobalt-60 gamma source, stored at 0.5 C, and examined periodically for spoilage and total microbial population and composition. The preirradiation flora consisted of Achromobacter, Micrococcus, Pseudomonas, coryneforms, Lactobacillus, and Flavobacterium. Immediately after irradiation, Micrococcus, Achromobacter, coryneforms, and Bacillus were predominant. After storage under vacuum, the spoilage flora of the nonirradiated petrale sole was predominantly Pseudomonas; the spoilage flora of the 0.1-Mrad irradiated samples consisted of Pseudomonas and Lactobacillus; and that of the 0.2-, 0.3-, and 0.4-Mrad samples was almost entirely Lactobacillus.
The microfloral changes on irradiated petrale sole fillets during aerobic (packaged with oxygen-permeable film), refrigerated storage were determined by the identification of bacterial and yeast isolates to the generic level. The samples were irradiated at 0.0, 0.1, 0.15, 0.2, 0.3, and 0.4 Mrad by use of a cobalt-60 gamma source, were stored at 0.5 C, and were examined periodically for spoilage, total microbial population, and composition. The preirradiation flora of the fresh fillets consisted of coryneforms, Achromobacter, Micrococcus, Flavobacterium, Pseudomonas, and Lactobacillus. Immediately after irradiation, Micrococcus, Achromobacter, coryneforms, and Bacillus were predominant. The flora of the nonirradiated fillets at the time of spoilage consisted of Pseudomonas and Achromobacter. The flora of the irradiated fillets at the time of spoilage consisted of Achromobacter and Trichosporon.
Diquat (2 x 10(-4)m) inhibited both aerobic and anaerobic growth of Rhodospirillum rubrum. With photosynthetic cultures, diquat affected the synthesis of bacteriochlorophyll more readily than cell mass (turbidity). Diquat retarded the synthesis of bacteriochlorophyll and some protein more readily than that of other cellular constituents such as ribonucleic acid, deoxyribonucleic acid, and cell mass. With cells deficient in phosphate, diquat inhibited the uptake-conversion of inorganic phosphate completely only when 3-(3,4-dichlorophenyl)-1,1'-dimethyl urea and ascorbate were also present.
No detrimental effects of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) were observed when cells of Bacillus megaterium were grown from small inocula in nutrient media containing up to 100 mug of DDT/ml. However, when the ratio of DDT to biomass of resting cells was held constant, levels of DDT as low as 1 mug/ml (0.5 mug/mg of cell dry weight) enhanced the rate of death in the population. The lethal action of DDT was both time- and dose-dependent so that higher doses required less time to effect the same killing than did lower doses. Intact cells bound a maximum of about 1.7 mug of DDT/mg of cell dry weight, of which about 75% was localized in the protoplast membrane. Much of the bound DDT was subsequently lost to the suspending medium and the aqueous stability of the returned DDT was enhanced, possibly by association with solubilized cell materials. A small quantity of bound DDT was converted to 1,1-dichloro-2,2-bis(p-chlorophenyl)ethane, which was released from cells somewhat faster than DDT. Apparently the lethal action of DDT was related to its binding in the membrane, but respiration was not inhibited. The atypical macroscopic appearance of membranes isolated from treated cells suggested that cell death may result from altered membrane chemistry.
Whole cells or cell-free extracts of Aerobacter aerogenes catalyze the degradation of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) in vitro to at least seven metabolites: 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE); 1,1-dichloro-2,2-bis(p-chlorophenyl)ethane (DDD); 1-chloro-2,2-bis(p-chlorophenyl)ethylene (DDMU); 1-chloro-2,2-bis(p-chlorophenyl)ethane (DDMS); unsym-bis(p-chlorophenyl)ethylene (DDNU); 2,2-bis(p-chlorophenyl)acetate (DDA); and 4,4'-dichlorobenzophenone (DBP). The use of metabolic inhibitors together with pH and temperature studies indicated that discrete enzymes are involved. By use of the technique of sequential analysis, the metabolic pathway was shown to be: DDT --> DDD -->DDMU -->DDMS --> DDNU --> DDA --> DBP, or DDT --> DDE. Dechlorination was marginally enhanced by light-activated flavin mononucleotide.
Resting cells of Pseudomonas oleovorans PO-1R that had been grown on octane oxidized 1-alkenes containing 6 to 12 carbon atoms and 1,7-octadiene to their corresponding 1,2-epoxides. The microorganism was capable of growing on 1-octene but not on 1,7-octadiene as a sole carbon source. The optimal temperature, pH, and 1-octene concentration for 1,2-epoxyoctane production by the resting cells were 34 to 40 C, pH 7 to 8, and 1.5 mg of 1-octene per ml, respectively. Epoxide concentration reached a maximum after 150 min of incubation and subsequently declined. In the absence of 1-octene, the epoxide was metabolized readily by the resting cells. The amount of 1,2-epoxyoctane produced was dependent on the initial cell concentration. With larger cell populations, the amount of epoxide present after 60 min of incubation was less than the amount observed at lower population densities after the same time period. This relationship was attributed to the rapid depletion of 1-octene at high biomass concentrations and the resultant early initiation of epoxide degradation by the resting cells.
Eighteen species of Penicillium, one of Oidium and one of Paecilomyces were found to effect a stereospecific conversion of cis-propenylphosphonate to fosfomycin which was identified by paper chromatography and gas-liquid chromatography (GLC) of the trimethylsilyl esters. Penicillium spinulosum carried out the epoxidation only after the glucose substrate had been utilized. Glucose controlled the epoxidation since its residual concentrations in the broth severely depresses the reaction. At optimum levels of glucose, an epoxidation efficiency approaching 90% of olefin charged (0.2 g/liter) was obtained after 10 days of incubation. The olefin concentration could be increased to 0.5 g/liter when glucose was replaced by glycerol, whereby a 90% conversion to fosfomycin was attainable in 6 days. The high conversion efficiency, a good agreement between the GLC assay and bioactivity, are indicative of the levorotatory nature of the product.
Characteristics of a new Salmonella serotype, subgenus IV, are reported. Culture 5534-68 was recovered from the intestinal tract of Anolis biporcatus, an arboreal lizard found in deep forest tracts in Panama Province, Republic of Panama. The antigenic composition of this new serotype was found to be 50(1, 2, 3):z(4), z(24):-.
Two hundred eighty-five fungi, including 100 basidiomycetes and 35 yeasts, 75 actinomycetes, and 40 bacteria were screened for their ability to convert 5-anilino-1,2,3,4-thiatriazole (AT) to 5-(p-hydroxyanilino)-1,2,3,4-thiatriazole (p-HT). Eleven cultures were found that formed p-HT, which was isolated and whose structure was determined. Aspergillus tamarii NRRL 3280 formed 8.6 g of p-HT/liter from 10 g of AT/liter (78.9% conversion) in shaken flasks and 4.57 g of p-HT/liter from 6 g of AT/liter (69.8% conversion) in 30-liter fermentors. Washed cells of A. tamarii NRRL 3280 also carried out this conversion. 5-(o-hydroxyanilino)-1,2,3,4-thiatriazole (o-HT) was identified as a second product formed by Aspergillus terreus NRRL 1960.
Chemotherapy experiments carried out in vitro demonstrated that 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) was active against lymphocytic choriomeningitis virus and had an equivocal antiviral effect on Semliki Forest, herpes simplex, and vaccinia viruses. No antiviral effect was observed with BCNU against western equine encephalomyelitis, polio, and parainfluenza (HA-1) viruses. Activity of the drug was determined by inhibition of viral-induced cytopathogenic effect in KB or chick embryo cells and by reduction of virus titer in cell culture supernatant fluid. Maximal activity against the viruses was observed when drug and virus were incubated together for 30 min prior to addition to cells; essentially no activity could be demonstrated if BCNU and virus were added to cells with no prior incubation.
A prolongation in the lives of Swiss mice inoculated intracerebrally with lymphocytic choriomeningitis virus (LCM) was observed after treatment with 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU). A variety of treatment schedules, including therapy once or twice daily up to 17 days and single treatments at various times after virus inoculation, were employed. Virus titers ranging to greater than 10(4) were detected in the blood and brains of surviving drug-treated animals. In three comparative studies in which different treatment schedules were used, BCNU was shown to exert a protective effect approximately equal to that of methotrexate in LCM virus-infected mice. Tests were also carried out to investigate the activity of BCNU in mice experimentally infected with eastern equine encephalomyelitis (EEE) virus, western equine encephalomyelitis virus, Semliki Forest (SF) virus, herpes simplex virus, influenza virus strain PR8, vaccinia virus strain WR, Rous sarcoma virus, Friend leukemia virus (FLV), and poliovirus. Slight increases in life span were observed in the treated EEE, SF, and influenza PR8 virus-infected animals. Significant reduction in splenomegaly in FLV-infected animals treated with BCNU was demonstrated. The possible mechanisms of LCM virus inhibition by BCNU, on the basis of these and other studies, were postulated to be either specific antiviral activity or inhibition of "lethal" immune response to the LCM virus. Each of these postulates is discussed.
The rate and extent of stereoselective reduction of 1,3-dioxo-2-methyl-2-(3'-oxo-6'-carbomethoxyhexyl)-cyclopentane to form the 1beta-hydroxy-2beta-methyl isomer by cultures of Schizosaccharomyces pombe ATCC 2476 was dramatically increased by addition to the fermentation of certain alpha,beta-unsaturated ketones and allyl alcohol.
10, 10'-Oxybisphenoxarsine has been found to be outstanding in its activity against bacteria and fungi. Parallel tests with known fungistats for comparison (2,3,4,6-tetrachlorophenol and phenylmercuric acetate) have demonstrated its superior activity and persistence in an exterior acrylate paint film and in an asphalt coating. In view of its superior antimicrobial activity and its persistence, it can be used in applications in which there is no danger of its ingestion. Further field trials are in progress to evaluate 10, 10'oxybisphenoxarsine in paint, asphalt, wood, and in marine pilings.
A potent beta-lactamase (EC 184.108.40.206) produced by a strain of Klebsiella aerogenes (K. pneumoniae), 1082E, isolated from a hospital patient, has been examined. Its properties were different from those of most gram-negative beta-lactamases previously reported. The enzyme has been partly purified, and its activity against a range of substrates has been compared with that of the enzyme from Enterobacter cloacae (Aerobacter cloacae) P99. The K. aerogenes enzyme, although predominantly a penicillinase, had a wide range of specificity. In addition to hydrolyzing the cephalosporins, it attacked the normally beta-lactamaseresistant compounds methicillin and cloxacillin as well as cephalosporin analogues with the same acyl substituents. The results obtained with the E. cloacae enzyme confirmed its cephalosporinase activity and showed that, unlike the enzyme from K. aerogenes, it was relatively inactive against the penicillins.
A strain of group A Streptococcus which was virulent but M-nontypable was isolated from patients in a hospital nursery during an epidemic. This strain, Boston 11, reacted in T-agglutination tests with antisera for types 9 and 11, an unusual combination. A comparison of this strain with Lancefield's M-11 strain (NCDC SS-721) and Alabama 11 (Provisional 61) revealed three serologically related but distinct strains. Antiserum produced with the Boston 11 strain exhibited similar reactivity with all three "11" strains as well as with M-9 (SS-501) as demonstrated in precipitin tests. Immunodiffusion studies indicated that the Boston 11 antigen was partially identical with the M-11 and M-9 strains and shared at least one antigen with the Alabama 11 strain. The Boston 11 antiserum could be made specific for precipitin tests, but bactericidal activity for the Alabama 11, M-11, and Boston 11 strains was essentially negative.
Microbiological profiles were determined for surfaces of the command module, lunar module (ascent and descent stages), instrument unit, Saturn S-4B stage, and the spacecraft lunar module adapter of the Apollo 10 and 11 spacecraft. Average levels of contamination of the command module were 2.1 x 10(4) and 2.7 x 10(4) microorganisms per ft(2) for Apollo 10 and 11, respectively. With the exception of the exterior surfaces of the ascent stage of the lunar module and the interior surfaces of the command module, average levels of microbial contamination on all components of the Apollo 11 were found to be lower than those observed on Apollo 10. For each Apollo mission, approximately 2,000 colonies were picked from a variety of media and identified. The results showed that approximately 95% of all isolates were those considered indigenous to humans; the remaining were associated with soil and dust in the environment. However, the ratio of these two general groups varied depending on the degrees of personnel density and environmental control associated with each module.
Most media have been unreliable when used to determine the number of coagulase-positive staphylococci in meat pot pies in the presence of overwhelming numbers of Bacillus cells. Various metabolic inhibitors were tested to determine whether they would suppress the growth of Bacillus cells without appreciably affecting the staphylococcal growth. The use of Staphylococcus Medium No. 110 modified by the addition of 0.75 mM sodium azide appears to be practical for the isolation of small numbers of coagulase-positive staphylococci from frozen meat pot pies.
Measles vaccines were prepared from the same virus fluids by inactivation with formaldehyde or by extraction with ether, ethyl acetate, or Freon 113 in the presence of Tween 80. Tests of antigenic potency, based on antibody levels in guinea pigs, showed that the formaldehyde-inactivated vaccines were more potent than the solvent-inactivated preparations and had the additional advantage of long shelf life. Residual Tween 80 in the solvent-extracted vaccines resulted in marked loss of immunogenic potency without significant loss of hemagglutinating activity. Neither extraction with organic solvents nor exhaustive dialysis efficiently removed Tween 80 from aqueous solutions.
Twenty-two species of lichens from 10 different genera possessed a hemagglutinin for one or more of human, sheep, horse, cow, rabbit, guinea pig, and chicken erythrocytes. Hemolysins were also detected occasionally, but these were only active at low dilutions. In those species tested, the hemolytic principle was dialyzable; the hemagglutinating agent was not. Preliminary studies have indicated that the lichen hemagglutinins are nonspecific.
The ester ethyl butyrate is produced by Zoogloea ramigera 115, a bacterium isolated from an aerobic waste treatment plant, when ethanol is present in culture media. The cells appear to produce butyric acid which is then esterified with residual ethanol in the culture medium.
Polybrene or diethylaminoethyl dextran, when added with murine leukemia or sarcoma virus inocula, significantly increased virus infectivity of BALB/3T3 cells. Residual polycation concentrations were nontoxic.
Pea extract contains a factor which improves recovery counts of heat-stressed putrefactive anaerobe spores in a complex medium up to threefold. The factor is heat-stable and nondialyzable. Most of the active principle is found in the precipitate which forms during storage of pea extract at 4 C. The precipitate disperses upon heating, is high in starch content, and retains activity after extraction with organic solvents and water. Treatment of pea extract with alpha-amylase results in complete destruction of the active principle. These observations indicate that starch is the factor in pea extract responsible for increased recovery counts of heat-stressed putrefactive anaerobe spores.
Staphylococcal enterotoxins, Types A, B, and C, were labeled with 1252 by the chloramine-T method at approximately two levels of specific activity, 40 and 4 muCi/mug of protein. Toxins labeled with high specific activity showed extensive dissociation of 125I when stored at different temperatures, including -23 C. In contrast, toxins labeled with low specific activity did not show any significant loss of 125I when stored at -23 C for as long as 2 months. Enterotoxins, whether labeled with high or low activities, formed aggregates immediately upon labeling. Aggregate formation increased in high-activity-labeled toxins on storage at -23 C, and low-activity-labeled toxins showed no significant increase in aggregate formation, even after 2 months at -23 C. The aggregated forms of the enterotoxins were either devoid of antigenic activity in solid-phase radioimmunoassay or they possessed significantly reduced antigenic activity. Thus, a decrease in binding of 1252-labeled enterotoxin to specific antibody in solid-phase radioimmunoassay results mainly from (i) loss of 125I on storage, and (ii) formation of aggregates with reduced antigenic activity.
Japanese quail (Coturnix coturnix japonica) fibroblast cell culture monolayers were found to provide a very satisfactory system in which to propagate and assay turkey herpesvirus FC-126, which is used for production of Marek's disease vaccine. Japanese quail cells were more sensitive than duck cells and of approximately equal sensitivity to chicken cells. Foci of infection developed rapidly and uniformly, were of larger size, and were more easily discernible in quail cells than in chicken cells.
Geosmin, an earthy-smelling substance, has been isolated from several actinomycetes. Production of 1 mg per liter of whole broth was obtained from Streptomyces griseus LP-16. After preliminary separations, pure geosmin was isolated in milligram amounts by gas chromatography. Geosmin is a neutral oil, with an approximate boiling point of 270 C, which contains carbon and hydrogen, but no nitrogen. It undergoes a reaction with acid to give odorless argosmin, a neutral oil, with an approximate boiling point of 230 C, which contains only carbon and hydrogen. Specific rotation and ultraviolet- and infrared-absorbtion spectra were determined for both.
Accumulation and elimination of viral particles by hard clams, Mercenaria mercenaria, were studied with the coliphage S-13 as a working model. Escherichia coli uptake and elimination were simultaneously monitored. Clams were exposed to low levels of S-13 (7 particles/ml) in running seawater for several days, achieving titers in tissues from 2 to more than 1,000 times the levels to which they had been exposed. Bacterial accumulation (previously established by other workers) was comparable. Upon exposure to virus-free running water, clams polluted to relatively low levels (100 plaque-forming units/ml) eliminated most of their bacterial contaminants in 24 to 48 hr. Viral contaminants, however, persisted for several days to weeks even under ideal conditions for clam activity, provided that the temperature remained below the inactivation threshold for the virus. Most of the accumulated virus appeared to be sequestered in the digestive gland. These sequestered particles are refractory to those mechanisms responsible for elimination of bacterial contaminants. This discrepancy points out the need for caution in evaluating the efficiency of shellfish depuration processes, especially if only a bacterial criterion is used as a monitoring system.
Thirteen isolates of Nocardia caviae from 12 different clinical sources were received and identified over a 5(1/2)-year period by the Mycology Division of the Center for Disease Control. The results of morphological, biochemical, and physiological studies on these isolates were compared with those obtained with four reference cultures of N. caviae received from the Institute of Microbiology, Rutgers University. Comparison showed that N. caviae isolates form a homogeneous group that is usually easily distinguished from N. asteroides, N. brasiliensis, and other pathogenic aerobic actinomycetes. The clinical sources included nine human and two animal infections and one human isolate apparently not associated with disease. Previous reports of N. caviae infections in man have been limited to rare cases of actinomycotic mycetoma. Among the human infections reported in this series are one case of mycetoma, one case of "mycotic" keratitis, one case of skin abscess, two cases of osteomyelitis, and four cases of serious pulmonary infection caused by N. caviae.
The effect of relative humidity (RH) on the airborne stability of two small bacterial viruses, S-13 and MS-2, was studied. Poorest recovery of S-13 was obtained at 50% RH. Humidification prior to aerosol sampling significantly increased the recovery of S-13 at RH deleterious to the airborne virus. A commercial preparation of MS-2 suspended in a buffered saline solution showed a rapid loss of viability at RH above 30%, whereas a laboratory preparation containing 1.3% tryptone showed high recoveries at all RH studied. Dilution of the commercial MS-2 into tryptone broth conferred stability on the airborne virus. Humidification prior to sampling significantly reduced the viable recovery from aerosols of commercial MS-2, whereas the laboratory preparation was unaffected.
This report describes the methods used to obtain high titers of chikungunya virus with suspension cultures of BHK-21-clone 13 cells. The cells were grown at 37 C to a cell concentration of 10(6) to 2 x 10(6) per ml. After maximum cell growth, the cells were inoculated with chikungunya virus at a multiplicity of 1 to 2 50% suckling mouse intracerebral lethal doses (SMICLD(50)) per cell in the spent Eagle's minimum essential medium for suspension cultures (MEMS), or the cell cultures were centrifuged at 200 x g and resuspended in either fresh MEMS or medium 199 prior to inoculation. The medium used had no effect on virus titer. The inoculated cultures were incubated at 34 C until the cell viability dropped to 30%, which usually occurred 28 to 30 hr postinoculation. After these procedures, chikungunya virus titers of log(10) 10.3 to 11.8 SMICLD(50) per ml were obtained.
The effects of administering low levels of aflatoxin B(1)-(14)C by crop intubation daily for 14 days to broiler chickens were determined. Studies on the distribution of (14)C in the blood, selected organs, tissues, and excreta were conducted. No toxic effects were observed in broiler chickens during the 14 days of the experiment. The broiler chickens excreted 90.64% of the (14)C administered. Of the (14)C retained, 11.04, 9.83, 4.30, 12.52, 31.66, and 30.63% were detected in the blood, liver, heart, gizzard, breast, and leg, respectively. Chemical assay of those samples demonstrating radioactivity revealed that 81.2% of the radioactivity in these substrates was not extractable by classical extraction procedures while approximately 10% was extractable. Treatment of aqueous extracts for conjugated steroids by treatments with beta-glucuronidase revealed that 31.5% of the (14)C detected in the aqueous extract was a liberated glucuronide conjugate of aflatoxin M(1)-(14)C.
Evidence is presented for the isolation and identification of bacteria able to synthesize an unusual antibiotic containing five bromine atoms per molecule. The identification and taxonomic position of these bacteria was made by use of a computer in conjunction with traditional methods. These microorganisms and closely related strains have been isolated on various occasions from tropical water in the vicinity of Puerto Rico. One bacterium, a pseudomonad, has been given the name Pseudomonas bromoutilis because of its distinctive capability. The antibiotic has been extracted, purified, and obtained in crystal form, and its structure has been determined. Although clinical tests of its properties were not encouraging, it may be of significant value and interest from an ecological standpoint.
Fermentative capabilities of 140 strains of Actinobacillus actinomycetem-comitans were studied. Findings correspond closely with those reported previously by Heinrich and Pulverer (12 strains), and by King and Tatum (33 strains). All strains ferment glucose, levulose, and maltose and reduce nitrate to nitrite. Reactions with glycogen and starch are exceedingly diverse. Eight different biotypes have been identified on the basis of their reactions with galactose, mannitol, and xylose.
Methods using dialysis or ultrafiltration are described for the collection of extracellular fluid in rumen contents for analysis of amino acids. Marked differences in the concentration of aspartic acid, glutamic acid, and alanine were found in samples of either diffusate or ultrafiltrate and in clarified acidified rumen liquor. Concentrations are given for aspartic acid, glutamic acid, alanine, glycine, gamma-aminobutyric acid, valine, delta-aminovaleric acid, and leucine.
The in vitro and in vivo incorporation of (2-14C)acetate into lipids of mink (Mustela vison) liver and intestines was studied. In vitro, a dose of aflatoxin B1 as small as 7.5 mug/ml of medium reduced by 20% the amount of (2-14C)acetate incorporated into lipids of mink liver slices, whereas 180 mug caused 76% reduction in the synthesis of lipids from the radioactive precusor. Similar inhibition of lipid synthesis by aflatoxin also was observed with tissues from mink intestines and fatty liver. The degree of inhibition (19 to 84% for tissue from intestines and 19 to 64% for tissue from fatty livers) depended on the amount of aflatoxin B1 (7.5 TO 180 MUG) present in the medium. In vivo, a substantially increased amount of 14C-labeled lipids was found in the livers of mink injected with 600 mug of aflatoxin B1 per kg of body weight 20, 28, and 40 h earlier. However, no appreciable difference in incorporation of (2-14C)acetate into lipids was observed between toxin-treated and control animals when these animals were sacrificed and examined for 14C-labeled lipids at 4 and 10 h after toxin was administered.
A study on skin cross-reactivity between stabilized (14)C-labeled mycobacterial antigens, namely tuberculin purified protein derivative (PPD; from Mycobacterium tuberculosis), PPD-A (M. avium), PPD-Y (M. kansasii), PPD-G (M. scrofulaceum), PPD-B (M. intracellulare), and PPD-F (M. fortuitum), has been carried out in groups of guinea pigs sensitized with one of the following heat-killed mycobacteria: M. tuberculosis, M. avium, M. kansasii, M. scrofulaceum, M. intracellulare, or M. fortuitum. For each type of sensitization, the average response for the corresponding PPD antigen was higher than the average response for any of the other antigens. However, the responses to the heterologous PPD antigens were not necessarily significantly different among themselves, and the significant differences of the heterologous PPD antigens were distributed differently according to the type of sensitization. Therefore, (14)C-PPD antigens skin cross-reacted in guinea pigs essentially in the same manner as reported by others for nonradioactive PPD antigens.
Rhodotorula gracilis metabolizes Chlorobenzilate (ethyl 4,4'-dichlorobenzilate) and Chloropropylate (isopropyl 4,4'-dichlorobenzilate) to several metabolites in a basal medium supplemented by sucrose and by several intermediates of the citric acid cycle. Three identified metabolites resulting from the degradation of either acaricide, were 4,4'-dichlorobenzilic acid, 4,4'-dichlorobenzophenone, and carbon dioxide. Chlorobenzilate, i.e., ethyl ester of 4,4'-dichlorobenzilic acid, was more easily hydrolyzed than Chloropropylate, i.e., isopropyl ester of this acid, so that larger amounts of carbon dioxide and 4,4'-dichlorobenzophenone were obtained from Chlorobenzilate degradation. Regardless of acaricides used, longer incubation caused a higher accumulation of 4,4'-dichlorobenzophenone. The probable steps of the degradation pathway are: Chlorobenzilate (or Chloropropylate) --> 4,4'-dichlorobenzilic acid --> 4,4'-dichlorobenzophenone plus carbon dioxide. It appears that the decarboxylation of 4,4'-dichlorobenzilic acid to 4,4'-dichlorobenzophenone was hindered by alpha-ketoglutarate and enhanced by succinate.
Biologically active (14)C-labeled purified protein derivative ((14)C-PPD) has been prepared from the culture filtrates of seven species of mycobacteria, namely Mycobacterium tuberculosis Johnston strain (PPD), M. bovis BCG (PPD-BCG), M. avium (PPD-A), M. kansasii (PPD-Y), M. intracellulare (PPD-B), M. scrofulaceum (PPD-G), and M. fortuitum (PPD-F). These mycobacteria were grown in a culture medium containing a mixture of (14)C-labeled amino acids. The yield and specific radioactivity of the PPD, of the nucleic acid, of the bacterial cells, and of the CO(2) developed during growth have been determined for each of the seven species of mycobacteria. Although the yields of (14)C-PPD antigens differed greatly for the different species of mycobacteria tested, their specific radioactivities were similar. The (14)C-PPD antigens have been used as a means to measure their adsorption to glass. When glass ampoules containing dilute solutions (0.001 mg of PPD per ml) of these PPD antigens (PPD, PPD-BCG, PPD-A, PPD-Y, PPD-G, PPD-B, and PPD-F) were stored for 12 months at 5 C, it was found that they all adsorbed equally well to glass surfaces. In fact, regardless of the origin of the PPD, a loss due to adsorption of about 90% occurred during the first month of storage, and thereafter the PPD content remained practically constant for the rest of the duration of the storage period. The addition of 0.0005% Tween 80 to the PPD solutions effectively reduced the adsorption to glass of most PPD antigens. However, adsorption of PPD-BCG was not quite so effectively prevented, even when the Tween 80 concentration was increased from 0.0005 to 0.0005%.
Evolution of (14)CO(2) by whole blood as well as by Diplococcus pneumoniae, Haemophilus sp., Pseudomonas aeruginosa, Pseudomonas diminuta, and Streptococcus pyogenes was examined by using the BACTEC system. The control medium was JLI no. 6A culture vial containing 30 ml of enriched tryptic soy broth and 1.5 muCi of (14)C-substrate. Hypertonic media consisted of control medium with either 1 or 3% NaCl, 10% sucrose, and 5%, 10%, or 15% dextran. The most deleterious treatment to bacteria was 3% NaCl since it not only retarded (14)CO(2) production, but also prevented growth of D. pneumoniae, Haemophilus, and P. diminuta. The 10% sucrose treatment diminished (14)CO(2) output, although it did not retard growth of test organisms. This effect was probably due to (14)C-substrate dilution rather than to osmotic effects. Dextran had slight effect on (14)CO(2) production and slightly acidified the medium. Of the treatments tested, only 10% sucrose reduced normal output of (14)CO(2) by whole blood. This also is probably due to (14)C-substrate dilution. It appears that 10% sucrose is potentially the most useful osmotic agent for radiometric techniques since, although bacterial (14)CO(2) production is lowered, blood (14)CO(2) is lowered also.