Non-pigmented Strains Research Articles

Biological inactivation by single oxygen: distinguishing O 2( 1Δg) and O 2( 1Σg+)

Experiments were performed to determine whether bacterial inactivation in the separated-surface-sensitizer system for singlet oxygen generation is due to O 2( 1 Δ g) or O 2( 1 Σ g +). The rates of inactivation of Gram-negative Salmonella typhimurium LT-2 and a nonpigmented strain of Gram-positive Sarcina lutea were found linearly with the concentration of 1 Δ g. The gas phase lifetime of the inactivating agent was found to be within the range of values expected for the gas phase lifetime of 1 Δ g rather than 1 Σ g +. These measurements conclusively demonstrate that bacterial inactivation in this system is due predominantly to 1 Δ g. Therefore, studies of bacterial inactivation with this singlet oxygen generating system can be used to assess the role of singlet oxygen in various biological and medically relevant situations.

The possible mechanism of naphthalene cataract in rat and its prevention by an aldose reductase inhibitor (ALØ1576)

The naphthalene-induced cataract in rats has been studied for many years as a possible model of human aging-related cataract. While the molecular mechanism of this cataract is unclear, it has recently been demonstrated that the aldose reductase inhibitor ALØ1576 can prevent lens opacification in this system. The present study was undertaken to investigate the molecular basis for the effects of naphthalene on the lens and the role of pigmentation in the cataractogenic mechanism. Cataracts were induced in five strains of rats (two pigmented, three albino) by oral administration of naphthalene. Initial lens changes were observed after 1 week by slit-lamp; by 3 weeks a distinct shell-like opacity was present in the deep cortex. Little difference in the course of opacification was found between the pigmented and albino strains. Major biochemical effects were a decrease of 20–30% in glutathione (GSH) by 1 week of feeding, disulfide cross-linking of lens proteins present by 3 weeks, and a nearly 20-fold increase in the content of protein-GSH mixed disulfide. No effect was seen in the ability of the affected lenses to accumulate actively [ 3H]choline or 86Rb from the medium in organ culture nor in the activity of the Na + K + -ATPase . ALØ1576 (10 mg kg −1 day −1) completely prevented all morphological and biochemical changes in the lenses of the naphthalene-fed rats in both pigmented and non-pigmented strains. These results indicate that pigmentation is not required for induction of naphthalene cataract in rats. Naphthalene dihydrodiol was found in the aqueous humor and lens of naphthalene-fed rats. It is proposed that naphthalene dihydrodiol produced in the liver reaches the aqueous humor and penetrates the lens where it is further metabolized ultimately to form the toxic species, naphthoquinone.

Evaluation of the influence of optic stalk melanin on the chiasmatic pathways in the developing rodent visual system

In a number of mammalian species, fibre outgrowth in the developing retinofugal pathway is coincident with the presence of melanin in the retinal part of the optic stalk. The presence of melanin is transient in this developing system and has been proposed to play a role in the guidance of retinofugal fibres. Further, it has been suggested that this stalk melanin accounts for the differences between the size of the uncrossed retinal component in pigmented and nonpigmented strains. However, a recent study showed that there is no melanin in the optic stalk of Manchester rats during fibre outgrowth. Since such rats supposedly have a normal pigment distribution and a normal pattern of decussation at the optic chiasm, this finding appears to undermine the suggested role played by stalk melanin in establishing the laterality of retinal fibre projections in other mammalian species. The aim of this study was to re-evaluate the relationship between melanin in the stalk and the development of the retinofugal pathway in three strains of rat: the Wild type, Long Evans Hooded, and the Albino. The Albino rat, which lacks melanin-bearing cells entirely, was shown to have the smallest uncrossed projection, approximately 1,340 ipsilaterally projecting cells (ipc), whereas the Long Evans (2,760 ipc) and the Wild-type strain (2425 ipc) were found to have a larger uncrossed retinal component. In both pigmented strains, melanin was restricted to the eye cup and absent from the optic stalk throughout all stages of development.(ABSTRACT TRUNCATED AT 250 WORDS)

Polar Lipid and Fatty Acid Composition of Strains of the Genus Thermus

Summary Eighteen isolates and five reference strains of the genus Thermus were examined for polar lipid patterns and fatty acid composition. All high-temperature yellow or nonpigmented strains had a major glycolipid and a major phospholipid, and minor, slightly variable components. The red-pigmented strains, related to Thermus ruber, had two prominent glycolipids in addition to the major phospholipid. With the exception of Thermus filiformis, all strains had iso-C15 and iso-C17 fatty acids as major components, followed by lower relative proportions of the anteiso-brmched fatty acids. In contrast, anteiso-branched fatty acids were predominant in T. filiformis. Principal component analysis of the fatty acid results did not reflect the classification of the members of the genus Thermus.

Taxonomic Relationship of Black-Pigmented Bacillus subtilis Strains and a Proposal for Bacillus atrophaeus sp. nov.

The taxonomic position of Bacillus subtilis strains that produce soluble black pigment is unclear. To assess the genetic relatedness between the pigmented and nonpigmented strains, deoxyribonucleic acid (DNA) reassociation was measured spectrophotometrically. Among the 40 pigmented strains examined, two distinct DNA relatedness groups were found. A total of 25 strains (group 1) showed 24 to 34% DNA relatedness and 15 strains (group 2) showed 70 to 100% relatedness to Bacillus subtilis type strain NRRL NRS-744. The intragroup DNA relatedness values for each group ranged from 85 to 100%; the intergroup relatedness values ranged from 20 to 35%. A multilocus enzyme electrophoresis analysis revealed a low level of similarity between group 1 and group 2 or the nonpigmented group. The group 2 strains and the nonpigmented strains clustered in a common group, indicating the close genetic relationship of these organisms. My results strongly suggest that group 2 is a pigmented variant of B. subtilis, but group 1 is a new species, for which the name Bacillus atrophaeus is proposed. The type strain of the new species is strain NRRL NRS-213.

A Protein Associated with Prodigiosin Formation in Serratia marcescens

A protein associated to prodigiosin formation was found in Serratia marcescens. The protein was not found in nonpigmented strains and was correlated with the pigment level. The protein was about 100 kilodaltons (kDa) and was also found in nonpigmented bacteria of the pigmented strain grown in glucose medium, at high temperature, or under anaerobic condition. The 100 kDa protein was found not in the outer membrane and the periplasm, but in the inner membrane and/or the cytoplasm. The protein was also found singly or dominantly in pigment-protein complexes and pigment-localizing vesicles described in previous reports. These results suggest that the 100 kDa protein is associated with prodigiosin formation.

Gas vacuolate bacteria obtained from marine waters of Antarctica

Several strains of heterotrophic, gas vacuolate bacteria were isolated from marine waters of Antarctica. To our knowledge these are the first marine forms of gas vacuolate bacteria to be reported. Current isolates are all Gram-negative rods. All isolates are psychrophiles that grow at temperatures between ≤−1.5°C and 7°C, with none growing at temperatures higher than 14°C. All can grow at salt concentrations of sea water, although some can grow at 1/16th that concentration. Two of the strains produce orange colored pigments, whereas all heterotrophic gas vacuolate bacteria known to date are nonpigmented. The two pigmented filamentous strains grow well at 5.0% NaCl and have a specific sodium ion requirement. Isolates differ in the substrates they use for growth. Organic acids, amino acids, and sugars are used depending upon the strain. All isolates appear to be microaerophilic and oxidase and catalase positive. All grow well at pH 7.0. The mol% G+C of the pigmented strains is 31 and that of the non-pigmented strains, 52–57.

Studies on the virulence properties and metabolism of pleiotropic mutants of Porphyromonas gingivalis (Bacteroides gingivalis) W50.

Porphyromonas gingivalis (Bacteroides gingivalis) strain W50 and variants isolated from continuous culture designated W50/BP1 (black pigmented), W50/BR1 (brown pigmented) and W50/BE1 (beige or non-pigmented) were previously shown to lose virulence with the loss of pigmentation. Major properties which may affect the virulence and metabolism of P. gingivalis were compared amongst the 4 strains. The non-pigmented strain lost the ability to hemagglutinate sheep erythrocyte, had a reduced hydrophobicity and possessed lower levels of proteolytic activity. Defects in the electron transport system occurred at the level of cytochrome b but not menaquinone synthesis and resulted in an altered metabolic end product profile of the non-pigmented strain.

Induction of Yellow Pigmentation in Serratia marcescens

The appearance of yellow pigmentation in nonpigmented strains of Serratia sp. has been demonstrated to be due to the production of a muconic acid, 2-hydroxy-5-carboxymethylmuconic acid semialdehyde. The 3,4-dihydroxyphenylacetate 2,3-dioxygenase responsible for the synthesis of this muconic acid was induced in all strains tested. Another muconic acid, the beta-cis-cis-carboxymuconic acid, could also be synthesized from 3,4-dihydroxybenzoate, but this product was not colored. Mutants that were unable to grow on tyrosine and produced yellow pigment were isolated from nonpigmented strains. These mutants had properties similar to those of the yellow-pigmented strains. The ability to produce pigment may be more widespread among Serratia marcescens strains than is currently known.

Viability of blastocysts produced by aggregation of two half-embryos in the mouse

Although methods for production of chimeras from early cleavage stages have been well established, little research has been directed toward production of genetically identical chimeric offspring. This study was designed to examine survival of blastocysts produced by aggregation of two halved eight-cell stage embryos from two different mouse strains. Four blastomeres of an eight-cell embryo from a pigmented strain were aggregated with four blastomeres of an eight-cell embryo from a nonpigmented strain. Aggregates were cultured for 48 h and transferred as blastocysts to synchronized recipients of three treatment groups. Viability was determined by examining the number of offspring produced relative to the number of blastocysts transferred. Thirty-nine pups were born from 375 transferred blastocysts (10%), with 16 pups displaying coat-color chimerism. Both nonmanipulated eight-cell embryos cultured for 48 h (P < 0.05) and chimeric blastocysts (P < 0.001) displayed lower embryo survival after transfer to recipients than noncultured, nonmanipulated blastocysts used as controls. Viability of chimeric blastocysts was also lower than that of nonmanipulated embryos cultured for the same period and transferred to the same recipients (P < 0.001). Although posttransfer survival of chimeric blastocysts was low, the birth of morphologically normal offspring demonstrated that production of chimeras from half embryos was compatible with survival. Improvements in this procedure may be useful for production of tenetically identical chimeras from outbred populations, such as those commonly found in domestic livestock species.

Frequency of antibiotic and heavy metal resistance, pigmentation, and plasmids in bacteria of the marine air-water interface.

A field investigation of marine coastal waters revealed that the frequency of pigmented bacteria and the occurrence of bacterial antibiotic resistance were higher at the air-water interface than in the bulk water. The differences in the frequency of pigmented colonies at the surface and in the bulk-water samples could not be explained by the degree of cell surface hydrophobicity or by bacterial adhesion to air-water interfaces. Pigmented strains exhibited a higher degree of multiple drug resistance than did nonpigmented strains. However, the frequency of multiple drug resistance in nonpigmented strains was also substantial. An average of 91% of all strains were resistant to more than one antibiotic, and 21% of the bacteria isolated were resistant to five of the eight antibiotics tested. High numbers of plasmid-carrying strains were found among selected surface isolates, but the presence of detectable plasmids could not be correlated with either pigmentation or multiple drug resistance. Furthermore, selected surface isolates were significantly more resistant to mercury than were bulk-water bacteria. The higher frequency of pigmented, antibiotic-resistant, and mercury resistant strains at the air-water interface than in the bulk water are discussed in terms of various forms of selective pressure and genetic exchange at the surface.

Trimethyltin ototoxicity in albino rats

The toxicity of alkyltin compounds is of exceptional interest due to the dissimilar toxic effects of some very closely related structural analogues among this class of compounds. Since several features of the toxicity of trimethyltin appeared to be consistent with a mechanism involving accumulation of the toxicant on melanin pigments, the ototoxicity induced by TMT exposure was examined in albino rats. Hearing thresholds for tones sampling the mid- and high-frequency range of the rat's audibility function were assessed by reflex inhibition audiometry. TMT produced a frequency dependent loss of auditory sensitivity that was most severe in the high frequency range. The TMT-induced impairment of auditory function was similar to that previously observed in pigmented Long-Evans rats. These results extend the observation of TMT-induced hearing loss to a non-pigmented rodent strain and suggest that the accumulation of TMT on cochlear melanin is not critical to the production of hearing impairment by TMT.

口腔 Bacteroides species の β-lactamase に関する研究

For the purpose of assessment of production of β-lactamase, the bulk of pus samples collected from oral lesions (11 cases) and dental plaque of gingival crevice from 30 cases of patients and 23 cases of healthy adults were cultured. Then the β-lactamase activity in each culture was determined by iodometric method using CER and PCG as the substrates. Attempts were made to further isolate and identify the β-lactamase-producing strains from the positive cultures concerning β-lactamase production. Subsequently, β-lactamase was purified from one of the isolated strains, Bacteroides intermedius. The results obtained were as follows : 1. Out of the 64 above mentioned cultured samples, 4 pus samples and 10 dental plaque samples (21.9%) were found to contain β-lactamase. 2. The anaerobic strains which produced β-lactamase were of either black-pigmented or non-pigmented Bacteroides group. 3. The black-pigmented and non-pigmented Bacteroides strains which elabolated β-lactamasewere identified to be B. intermedius and Bacteroides heparinolyticus, respectively. 4. MICs of CER and PCG against both species of Bacteroides were rather high and there was a good correlation between the degree of β-lactamase production and MIC. 5. The majority of β-lactamase activity was found in the cell extract prepared by ultrasonic treatment, especially in the precipitate by ultracentrifugation including membrane fraction. No significant amount of the activity was detected in the culture fluid. 6. The enzyme could be solubilized from the ultracentrifugal precipitate with Triton X-100. 7. β-lactamase of B. intermedius was a hydrophobic protein with a molecular weight of 93, 000. Its isoelectric point was 4.4. The optimum pH was 7.0. 8. The enzyme was inactivated by heating at 60℃ for 10 min. PGE, TDC, K^+, Mg^<2+>, Zn^<2+>, Cu^<2+> and Fe^<2+> gave no effect on the activity, but it was inhibited by SDS, 1, 10-phenanthroline, or iodine. 9. The enzyme hydrolyzed cephem antibiotics (CER, CEX and CET) more preferably than penicillin group antibiotics including PCG, ABPC and CBPC. It was confirmed B. intermedius and B. heparinolyticus which were β-lactamase positive and resistant to various β-lactam antibiotics resided in the oral cavity. This enzyme may be membrane-bound and categorized in cephalosporinase. These findings indicate that great care should be taken in chemotherapeutic treatment for oral infections.

A preliminary grouping of new zealand Thermus strains by pyrolysis-mass spectrometry

Isolates belonging to the genus Thermus are readily obtained from many thermal environments but their exact identification is difficult because there is no general agreement on criteria which determine individual species. We present an attempt to determine natural groupings among Thermus strains using the technique of pyrolysis-mass spectrometry. A total of forty-four strains comprising forty isolates from New Zealand hot springs, one from a Fijian hot spring and three reference strains were pyrolysed in a Pyromass 8–80 and the resulting data analysed using multivariate statistical techniques. A dendrogram obtained by average linkage cluster analysis of discriminant distances showed clear discrimination of the three reference strains from each other and from the majority of the New Zealand strains. Thirty New Zealand isolates clustered within a single group, probably at a species level. At a higher level of similarity six sub-groups could be identified within this cluster which presumably represent grouping at a variety level. The non-pigmented reference strain “Ramaley's XI” occupied a rather isolated position in the dendrogram. It appears that pyrolysis-mass spectrometry is useful for rapid characterisation of isolates obtained from ecological studies and offers the possibility of detecting groupings at both species and sub-species levels.

Extracellular Vesicle Formation and Biosurfactant Production by Serratia marcescens

Summary: Pigmented and non-pigmented strains of Serratia marcescens produced extracellular vesicles and had wetting activity when grown at 30°C but not at 37°C. Light microscopy showed that the red pigment was present in vesicles and intracellular granules. Electron microscopy revealed the presence of vesicles surrounded by the bacterial membrane. Three lipids having the wetting activity, W1, W2 and W3, were isolated by thin-layer chromatography of lipids from different strains of S. marcescens. Dispersions of the isolated wetting agents had small contact angles on a polystyrene surface and the ability to lower surface tension. Wetting agent W1 was the aminolipid serratamolide. Wetting agents W2 and W3 were also aminolipids but were shown to be different from serratamolide by chemical analyses. Wetting agent and prodigiosin (in a pigmented strain) were the main lipids of isolated vesicles.

Cell surface hydrophobicity of pigmented and nonpigmented clinical Serratia marcescens strains.

The cell surface hydrophobicity of 10 pigmented and 4 nonpigmented clinical Serratia marcescens strains was studied, based on the ability of the strains to adhere to hydrocarbons and to polystyrene. The cell surface hydrophobicity depended greatly on growth temperature; all of the strains tested were adherent following growth at 30 degrees C, whereas none was adherent following growth at 38 degrees C. In previous studies, the pigment prodigiosin has been cited as responsible for cell surface hydrophobicity in various Serratia strains. However, the observed ability of the nonpigmented strains to adhere to the test hydrocarbons and to polystyrene indicates that Serratia strains can possess hydrophobic surface properties in the absence of this pigment. Moreover, strain 1785 cells were adherent whether they were grown at 30 or 36.5 degrees C, even though pigment was not synthesized at the higher temperature. In Escherichia coli correlations have been noted between increased cell surface hydrophobicity and the presence of mannose-specific adhesins; no such relationship was found in the S. marcescens strains tested. The expression of cell surface hydrophobicity in clinical S. marcescens strains at 30 degrees C and the loss of hydrophobicity at host temperatures raise the possibility that infective cells from the environment are initially hydrophobic, but lose this property upon subsequent proliferation within a host.

Enterococcus mundtii sp. nov.

Deoxyribonucleic acid base composition, deoxyribonucleic acid-deoxyribonucleic acid hybridization, and biochemical studies were performed on some problematic enterococci of unknown taxonomic position. Our results indicate that some motile, nonpigmented strains are members of Enterococcus gallinarum, whereas motile, yellow-pigmented strains belong to Enterococcus casseliflavus. Four nonmotile, yellow-pigmented strains were biochemically and genetically distinct from all previously described Enterococcus species and constitute a new species, for which the name Enterococcus mundtii is proposed. The type strain of Enterococcus mundtii is strain NCDO 2375.

Decrease in respiration activity related to prodigiosin synthesis in Serratia marcescens.

Variation in the cell respiration rate of pigmented and nonpigmented strains of Serratia marcescens was exhibited. The respiration rate of a pigmented strain decreased earlier than that of nonpigmented strains in the late exponential or early stationary phase. However when prodigiosin synthesis was not induced by exchange of carbon sources in the medium, the decrease in the respiration rate of the pigmented strain was the same as that of nonpigmented strains. Measurement of the oxygen consumption rate in the sonicated cell membrane by adding NADH solution showed that the rate in the pigmented strain was lower than that in nonpigmented strains. Furthermore, the cell membrane of prodigiosin-induced organisms was more sensitive to respiration inhibitors than that of pigment-noninduced organisms of the pigmented strain. These results showed that the respiration activity was decreased by prodigiosin synthesis in S. marcescens.

Influence of Serratia marcescens Pigmentation on Cell Concentrations in Aerosols Produced by Bursting Bubbles

For eight strains of Serratia marcescens, increased cell concentrations were found in aerosols produced from bursting bubbles, with concentrations ranging from a maximum of ca. 80 times the bulk concentration for pigmented strains 4180, 933, and 274 to a minimum approximately equal to the bulk concentration for nonpigmented strain 8100. The increased cell concentration in the aerosol was suppressed when pigmented strains were grown at 37 degrees C, a temperature at which the pigment prodigiosin is not synthesized, resulting in lower concentrations similar to those of nonpigmented strains. Strains that produce higher concentrations of prodigiosin after 1, 2, 4, and 8 days of growth show increasing concentrations in bubble-produced drops; duplicate cultures grown at 37 degrees C did not show any increases. In four concurrent experiments, cells starved for 24 h showed greater concentrations than nonstarved cells for chromogenic strain NIMA, whereas for nonchromogenic strain WF, starved cells showed greater concentrations in three cases and a decreased concentration in the fourth. Bacterial concentrations in aerosol drops from bursting bubbles appear to be predominantly influenced by the surface condition of the bacterial cell.

The kinetics of photoinactivation and long-term photosensitivity of pigmented and nonpigmented strains of the smut fungusUstilago violacea

White, pink, pumpkin, and yellow strains ofUstilago violacea containing high and low levels of cytochrome c and various carotenes were subjected to high light intensities to characterize the kinetics of photoinactivation. Additionally, these strains were grown at two light intensities to characterize their long-term resistance to photoinactivation. The orange strain 2.D37291S and yellow strain 1.C2y had the highest carotene contents and were the most light resistant in the kinetics and growth experiments. The pink strains 2.C425, AB278a-1, and 1.C421 accumulated cytochrome c as well as carotenes. These strains were slightly more photosensitive than the yellow or orange strains in the kinetics experiment but were much more sensitive in the growth experiment. The phytoene-containing white strain 2.C419, which contains a small amount of cytochrome c, had a high level of resistance to light in the kinetics and growth experiments. The carotene-less strains were most sensitive in the kinetics experiment but not in the growth experiment. The overall photosensitivity ofU. violacea strains is related to the carotene and cytochrome c contents.