Mycoplasma taxonomy studiedy electrophoresis of cell proteins

Mycoplasma agalactiae, an Etiological Agent of Contagious Agalactia in Small Ruminants: A Review

Mycoplasma agalactiae is one of the causal agents of classical contagious agalactia (CA), a serious, economically important but neglected enzootic disease of small ruminants. It occurs in many parts of the world and most notably in the Mediterranean Basin. Following the infection common complications are septicaemia, mastitis, arthritis, pleurisy, pneumonia, and keratoconjunctivitis. Primary or tentative diagnosis of the organism is based upon clinical signs. Various serological tests, namely, growth precipitation, immunofluorescence, complement fixation test, haemagglutination inhibition, agglutination, immunodiffusion, enzyme immunoassays, immunoelectrophoresis, blotting techniques, and others, are available. Molecular tools seem to be much more sensitive, specific, and faster and help to differentiate various strains. The real-time PCR, multiplex PCR, quantitative PCR, PCR-RFLP, MLST, and gene probes, complementary to segments of chromosomal DNA or 16S ribosomal RNA (rRNA), have strengthened the diagnosis of M. agalactiae. Both live attenuated and adjuvant (alum precipitated or saponified) inactivated vaccines are available with greater use of inactivated ones due to lack of side effects. The present review discusses the etiology, epidemiology, pathogenesis, and clinical signs of contagious agalactia in small ruminants along with trends and advances in its diagnosis, treatment, vaccination, prevention, and control strategies that will help in countering this disease.

Revised minimal standards for description of new species of the class Mollicutes (division Tenericutes)

Minimal standards for novel species of the class Mollicutes (trivial term, mollicutes), last published in 1995, require revision. The International Committee on Systematics of Prokaryotes Subcommittee on the Taxonomy of Mollicutes proposes herein revised standards that reflect recent advances in molecular systematics and the species concept for prokaryotes. The mandatory requirements are: (i) deposition of the type strain into two recognized culture collections, preferably located in different countries; (ii) deposition of the 16S rRNA gene sequence into a public database, and a phylogenetic analysis of the relationships among the 16S rRNA gene sequences of the novel species and its neighbours; (iii) deposition of antiserum against the type strain into a recognized collection; (iv) demonstration, by using the combination of 16S rRNA gene sequence analyses, serological analyses and supplementary phenotypic data, that the type strain differs significantly from all previously named species; and (v) assignment to an order, a family and a genus in the class, with an appropriate specific epithet. The 16S rRNA gene sequence provides the primary basis for assignment to hierarchical rank, and may also constitute evidence of species novelty, but serological and supplementary phenotypic data must be presented to substantiate this. Serological methods have been documented to be congruent with DNA-DNA hybridization data and with 16S rRNA gene placements. The novel species must be tested serologically to the greatest extent that the investigators deem feasible against all neighbouring species whose 16S rRNA gene sequences show >0.94 similarity. The investigator is responsible for justifying which characters are most meaningful for assignment to the part of the mollicute phylogenetic tree in which a novel species is located, and for providing the means by which novel species can be identified by other investigators. The publication of the description should appear in a journal having wide circulation. If the journal is not the International Journal of Systematic and Evolutionary Microbiology, copies of the publication must be submitted to that journal so that the name may be considered for inclusion in a Validation List as required by the International Code of Bacteriological Nomenclature (the Bacteriological Code). Updated informal descriptions of the class Mollicutes and some of its constituent higher taxa are available as supplementary material in IJSEM Online.

Taxonomic relationship of some members of Azotobacteraceae based on their protein profiles

Analysis of protein profiles of the members of Azotobacteraceae suggests that the genus Azotobacter consists of a heterogeneous group of bacteria, of which Azotobacter beijerinekii should possibly be separated to a new genus. Azomonas agilis and Azomonas macrocytogenes are only 26 percent related to each other.

Molecular biology and genetics of mycoplasmas (Mollicutes)

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Electrophoretic analysis of isoenzymes of mycoplasma species

The purpose of this paper is to further characterize and determine relatedness among some Mycoplasma species or serogroups of significant practical veterinary interest. Twenty-four strains were examined for the presence of 35 enzymes by horizontal starch gel electrophoresis, revealing a total of 127 different electromorphs of 30 enzymes. Inter- as well as intraspecific differences were found demonstrating the application of isoenzyme studies in classification as well as epidemiology. It is concluded that the F38 group of MacOwan and group 7 of Leach constitute 2 new species, The elevation of the 2 subspecies of M. mycoides (mycoides and capri) to species level is favoured, but it is suggested that a decision be taken internationally, considering the practical consequences of a given nomenclature. Three alternative possibilities for classification are presented.

Regarding identification the results suggest that the presence or absence of maltase and ornithine transcarbamylase indicate whether an isolate is related to the agent of contagious bovine pleuropneumonia or merely a representative of either the caprine LG type of M. mycoides subsp. mycoides or the classical caprine subspecies, M. mycoides subsp. capri.

Comparison of seven isolates of Mycoplasma meleagridis

A comparative study of seven isolates of Mycoplasma meleagridis indicated that they were indistinguishable morphologically. Two isolates, E2 and 8M92, induced hemagglutination of red blood cells of several different species while the others did not. Metabolic inhibition, growth inhibition and growth precipitation tests revealed minor differences among the seven isolates. According to these differences, isolates were divided into three groups: antiserum-sensitive isolate 1466, less sensitive isolates N, 8M92, RY3, 529 and E2 and insensitive isolate 1940. One dimensional polyacrylamide gel electrophoresis of cell proteins revealed that all isolates of M. meleagridis had virtually identical patterns and that they were electrophoretically distinct from Mycoplasma gallisepticum and Mycoplasma synoviae. When nonhemagglutinating isolate N, and hemagglutinating isolate E2 were examined by simple immunoelectrophoresis, no differences were detected. However, minor antigenic differences were detected between the two strains by means of two dimensional immunoelectrophoresis.

A comparative study of spirochaetes from the porcine alimentary tract

Strains of Treponema hyodysenteriae capable of inducing swine dysentery in specific pathogen-free pigs were compared with other spirochaetes from the porcine alimentary tract by biochemical and serological tests and by electrophoresis of their proteins. Carbohydrate fermentation and esculin hydrolysis were similar in all the spirochaetes. Indole was produced by T. hyodysenteriae and by some of the other spirochaetes. Analysis of the fatty acids produced from glucose showed a difference between T. hyodysenteriae and other spirochaetes only in the amount of n-butyric acid produced. The indirect fluorescent antibody test showed extensive cross-reactions between all the spirochaetes unless antisera were first absorbed. A microtitre agglutination test and a growth-inhibition test were both more specific; strains of T. hyodysenteriae could be distinguished from the other spirochaetes using unabsorbed sera. Both tests revealed some antigenic heterogeneity among strains of T, hyodysenteriae. The cell proteins of a single strain of T. hyodysenteriae gave an electrophoretic pattern distinct from those of the other spirochaetes. Two of the six spirochaetes not associated with swine dysentery, PWS/B and PWS/C, were indistinguishable serologically and electrophoretically. The other four strains were serologically distinct from one another and from PWS/B and PWS/C. Only two of these spirochaetes were examined electrophoretically, but each gave a different pattern from PWS/B and PWS/C. The diversity observed among spirochaetes not associated with swine dysentery indicates that their suggested inclusion in a single species, T. innocens, may prove to be unjustified.

Characterization of the strain-specific and common surface antigens of Mycoplasma arginini

A combination of quantitative immunoelectrophoresis and sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis was used to determine location and molecular weights of surface membrane antigens of four strains of Mycoplasma arginini. Two major surface antigens were identified for M. arginini by absorption of antiserum with whole cells: one surface antigen was strain specific, electrophoretically fast, and prominently located on the surface, whereas the other surface antigen was common to the four strains and of intermediate electrophoretic mobility. Three of the four strains of M. arginini (G-230, 23243, and 27389) possessed immunologically strain-specific antigens which did not cross-react, whereas the leonis strain lacked an immunologically detectable unique surface antigen. A monospecific antiserum prepared against immune precipitates of the strain-specific antigen of strain G-230 detected three polypeptides of 74,000, 44,000, and 17,000 daltons in SDS-polyacrylamide gels of membrane preparations. All four strains shared the common surface antigen which appeared considerably more hydrophobic than the strain-specific surface antigen because it could only be demonstrated by charge-shift immunoelectrophoretic conditions (addition of deoxycholate to the nonionic detergent). Monospecific antiserum to the common antigen of strain G-230 reacted with all four M. arginini strains, but did not react with two other arginine-utilizing species, and recognized three polypeptides of 40,000, 29,000, and 20,000 daltons in membranes of strain G-230. Whereas the common surface antigen is a likely target for conventional serological reactions used for identification of the species M. arginini, strain-specific antigen cannot fulfill this role but must participate in other surface reactions.

Two-dimensional gel electrophoretic comparison of proteins from virulent and avirulent strains of Mycoplasma pneumoniae

The protein composition of the virulent M129 strain of Mycoplasma pneumoniae was compared to that of its homologous avirulent strain by the use of standard one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Forty-nine individual M. pneumoniae cell proteins were resolved by this method, and the virulent strain was shown to possess a single high-molecular-weight protein not present in avirulent cells. Variability in the resolution of this particular protein in one-dimensional gels prompted the application of two-dimensional gel electrophoresis to the analysis of M. pneumoniae cell proteins. The sequential use of isoelectric focusing in the first dimension and sodium dodecyl sulfate-polyacrylamide gel electrophoresis in the second dimension permitted the resolution of a least 142 individual M. pneumoniae cell proteins. Application of nonequilibrium pH gradient electrophoresis in the first dimension achieved the resolution of at least 20 additional basic proteins. Three proteins which are synthesized only by cells of the virulent strain, and not by the homologous avirulent strain, were identified by these two-dimensional gel electrophoresis techniques.

Mycoplasmas in human pyelonephritis: demonstration of antibodies in serum and urine

This study was carried out to elucidate by serological examination the etiological significance of mycoplasmas isolated from the upper urinary tract of patients with pyelonephritis. The occurrence of antibodies in patients with acute pyelonephritis, chronic pyelonephritis with or without exacerbation, or noninfectious urinary tract disease was compared by the indirect hemagglutination method. Antibody response was demonstrated significantly more often in patients yielding growth of Mycoplasma hominis from the upper urinary tract than in patients not yielding growth. Antibodies against M. hominis were demonstrated in ureteric and bladder urine from three patients with acute pyelonephritis and from one patient with exacerbation of chronic pyelonephritis. M. hominis was isolated from the upper urinary tract of all four patients. Urine antibodies could not be demonstrated in any other cases. Thus, it seems highly possible that M. hominis may play a role in pyelonephritis of humans. The investigations did not disclose a similar role for Ureaplasma urealyticum.

The mycoplasmas

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Bovine mycoplasmas: classification of groups related to Mycoplasma mycoides

Mycoplasmas which had in various ways proved to be related to Mycoplasma mycoides were studied with a view to classification and nomenclature. Representative strains of M. mycoides — subspecies mycoides (PG1) and subspecies capri (PG3) — and of the as yet unclassified bovine serogroups 7 (PG50) and L (B144P) were compared serologically and by DNA-DNA hybridization. The serological methods used (metabolism inhibition, growth inhibition and immunofluorescence) are usually considered to be species-specific.

The two subspecies of M. mycoides can be clearly separated by all three serological methods, whereas the hybridization studies revealed great similarity between them, the relatedness value being 0.70.

The two serogroups (7 and L) cross-reacted with each other in all three serological tests, and their relatedness value was 0.83. The relatedness value between group 7 and M. mycoides subsp. mycoides was found to be 0.72, and only limited cross-reactions were demonstrated by immunofluorescence and growth inhibition.

Although groups 7 and L were found only to a slight degree to be genetically related to M. bovigenitalium with a DNA homology of 20 % or less, a serological cross-reaction between group 7 and M. bovigenitalium has been demonstrated by growth inhibition in previous studies.

Conclusions drawn on the basis of the premises just mentioned give rise to a dilemma, because three different situations exist. In (1), significant serological differences were disclosed, but the DNA homology was great. In (2), the serogroups 7 and L showed conformity between hybridization and serological findings, whereas, in (3), hybridization showed a distinct separation, but a serological cross-reaction does occur. If the results of hybridization are regarded as decisive, the two subspecies of M. mycoides can be preserved, but this is at variance with the general perception that the serological methods used here are species-specific. If, on the other hand, the serological results are chosen to be decisive, PG1 and PG3 must be regarded as two separate species, and consequently Group L/7 may also be a separate species.

As regards the relation between group L/7 and M. bovigenitalium, the results of hybridization clearly show that they are two different species. As a consequence of this, it must be accepted that cross-reactions may occur — also in growth inhibition — between different species which, genetically, are even far removed from each other.

On account of the fundamental nature of these problems, the authors prefer to leave the decisions — also as to the nomenclature — to the Subcommittee on the Taxonomy of Mycoplasmatales.

Isoelectric focusing of mycoplasma proteins

Polyacrylamide gel isoelectric focusing (PAGIF) in thin layer was used to resolve proteins of Mycoplasma spp., Acholeplasma spp., and eight strains of Ureaplasma urealyticum (T-strain). A mixture of urea, Triton X-100, and dithioerythritol was used to solubilize sonically disrupted cells. PAGIF was performed in the range of pH 3 to 10. Protein patterns were carefully compared, demonstrating resolved and distinguishable species-specific protein bands. The eight serotypes of U. urealyticum (T-strain) gave identical protein patterns in the pH 3 to 10 range. The characteristic "fingerprints" of a species appeared to correlate with the biochemical nature and not the habitat in each case. Arginine-hydrolyzing species seemed to show more diverse focusing than those that ferment glucose, or prefer an acid environment. Characterization and identification of highly resolved species-specific proteins, ease of performance, and reproducibility of this method suggest that PAGIF might be employed as a taxonomic aid.

Mycoplasmas isolated from the respiratory tract of horses

Ten mycoplasmas were isolated from 130 nasopharyngeal swabs from thoroughbred horses with acute respiratory disease and three from 198 apparently normal horses. Two mycoplasmas were isolated from 21 tracheal swabs taken at necropsy. These mycoplasmas, together with six isolated from the equine respiratory tract by other workers, were subjected to biochemical and serological tests. Other properties examined in certain representative strains were appearance under the electron microscope, ability to adsorb or agglutinate the erythrocytes of various animal species and the electrophoretic pattern of the cell proteins. On the basis of these test, mycoplasmas from the equine respiratory tract were divided into seven species. Three species belonged to the genus Acholeplasma, members of which do not require sterol for growth, and were identified as A. laidlawii, A. oculi (formerly A. oculusi) originally isolated from the eyes of goats, and a recently named species A. equifoetale, previously isolated from aborted equine fetuses. Of the four sterol-dependent Mycoplasma species, one was indentified as M. pulmonis, a common rodent pathogen. Another cross-reacted serologically with M. felis and should probably be classified as that species. The other two species probably represent new species peculiar to the horse. One of these, represented by the strains N3 and N11, ferments glucose and is serologically distinct from 19 recognized species of glucose-utilizing mycoplasmas and from two species which do not metabolize either glucose or arginine. The other species, represented by four strains, hydrolyses arginine and, because it is serologically distinct from all the named arginine-hydrolysing Mycoplasma species, the name M. equirhinis sp.nov. is proposed for it. Of the seven species, only M. pulmonis and the glucose-utilizing species represented by N3 and N11 were found exclusively in horses with acute respiratory disease. A. oculi was isolated from an apparently normal horse. The other four species were found in normal horses as well as those with respiratory disease, although three out of the four strains of M. equirhinis were from sick horses.

Flat gel polyacrylamide electrophoresis of porcine mycoplasmas

The flat gel acrylamide electrophoresis technique was standardized and applied to the comparison of four species of porcine mycoplasmas. Clear differences were observed between these species, and differences were seen among the strains of Mycoplasma hyosynoviae. The clarity of the patterns and the number of bands developed was influenced by the amount of protein in the extract and the age of the culture. The technique allows the comparison of several protein extracts in parallel without the problems associated with the rearrangement of separate gel columns.

Cell biology of the mycoplasmas

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Isolation and characterization of Mycoplasma conjunctivae sp. n. from sheep and goats with keratoconjunctivitis

Fourteen conjunctival strains of mycoplasma were isolated from infected sheep and goats in two separate naturally occurring outbreaks of keratoconjunctivitis (pink-eye). The biological and serological properties and cell protein patterns of these strains are presented in this report. These strains were related to each other and were unrelated to 40 recognized Mycoplasma and Acholeplasma species and serotypes. We are proposing that this group of mycoplasmas be named M. conjunctivae. The role of M. conjunctivae in the etiology of keratoconjunctivitis in sheep and goats remains to be determined.

Toxic membrane fractions from Mycoplasma fermentans

A recent isolate of Mycoplasma fermentans (strain K10, from human leukemic bone marrow) induced a lethal toxicity syndrome in mice. High doses of both viable and inactivated cells were toxic when injected intraperitoneally. Whole lysates and membranes from osmotically shocked cells killed mice, but cytoplasm did not. When membranes were dissolved in detergents and reaggregated by dialysis in the presence of Mg(2+), the lipid-protein complex thus formed was toxic. Lipids extracted from membranes with chloroform-methanol did not kill mice. Protein-rich fractions (obtained by reaggregation plus acetone washes or ammonium sulfate precipitation of dissolved membranes) were also not toxic. No qualitative differences in proteins from three toxic isolates and three nontoxic laboratory strains of M. fermentans were detectable by polyacrylamide gel electrophoresis. The toxic factor contained in reaggregated membranes was heat-stable but sensitive to Pronase, trypsin, and lipase.

Acrylamide gel electrophoresis of intracellular proteins during early stages of sporulation in Bacillus subtilis

Acrylamide gel electrophoresis of unfractionated cellular extracts of Bacillus subtilis is shown to be an effective method for characterizing many of the changes in protein composition, when coupled with specific histological-type staining reactions. The results obtained here by using extracts from cells at different stages of growth and sporulation are consistent with observations from other laboratories where extensively purified and highly characterized enzymes have been studied. In several instances, the histochemical reactions can be associated with a specific enzymatic function and appear to indicate the presence of multiple molecular forms. In other instances, the data cannot be evaluated in terms of known enzyme function because the specificity of the histochemical analysis is not certain. However, the assays described permit monitoring of electrophoretic changes at the level of individual proteins within sporulating cultures. The results suggest that B. subtilis may contain two "hexokinase-like" enzymes which cease to function before sporulation is initiated. Aldolase and alanine dehydrogenase are detectable as single bands of enzyme activity during vegetative growth but as multiple molecular forms once sporulation has been initiated. Reduced nicotinamide adenine dinucleotide dehydrogenase activity is represented by an entire family of reactive species in these crude extracts, which undergo multiple changes during the early stages of sporulation. Tricarboxylic acid cycle dehydrogenase enzymes and those bands having esterase activity on alpha-naphthyl acetate show detectable changes in specific activity after cessation of exponential growth. Glucose dehydrogenase is not detectable until the sequence of changes leading to spore formation has progressed for 4 or 5 hr.

Proposal for classifying human strain navel and related simian mycoplasmas as Mycoplasma primatum sp. n

Mycoplasmas isolated from simian (Cercopithecus aethiops) tissues were shown to have biological, biochemical, and serological properties and electrophoretic cell protein patterns similar to strain Navel isolated from man 15 years ago. The simian and human Navel strains comprised a single serogroup, distinct from the established Mycoplasma and Acholeplasma species of the class Mollicutes. It is proposed that strains with the properties described be named Mycoplasma primatum.

Serological cross-reaction between lipids of Mycoplasma pneumoniae and Mycoplasma neurolyticum

The complement-fixing activity of crude lipid extracts of 10 Mycoplasma species was compared with that of whole organism antigens employing immune rabbit serum. Five species (M. pneumoniae, M. neurolyticum, M. granularum, M. laidlawii, and M. fermentans) showed serological activity, whereas the remaining five species (M. canis, M. felis, M. gallisepticum, M. hyorhinis, and M. pulmonis) did not show significant activity in their lipid fractions. The lipid fractions of the five species which had serological activity in their lipid fractions showed three groups of serological specificity. M. pneumoniae cross-reacted with M. neurolyticum, M. granularum cross-reacted with M. laidlawii, and M. fermentans showed specific activity. Acute and convalescent sera from human pneumonia patients from whom M. pneumoniae had been isolated showed antibody increases which could be measured nearly as well by lipids of M. neurolyticum as by those of M. pneumoniae. Only a few human convalescent sera showed antibody measureable by lipids of M. granularum, M. pneumoniae did not cross-react with M. neurolyticum by other serological parameters such as growth inhibition on agar or double immunodiffusion, indicating that only the lipid antigens of these two species cross-react.

Morphology and ultrastructure of Mycoplasma pneumoniae spherules

During growth in fluid medium, most strains of Mycoplasma pneumoniae produce free-floating granules which become larger with time. We have called these granules "spherules." This study describes the morphological and ultrastructural features of M. pneumoniae strain AP-164 spherules, both free and in association with HeLa cells in cell culture. In thin section, spherules were composed of lobulated cells, connected together by membranes, and ring-shaped cells. The two-dimensional morphology observed varied according to the plane of section and to the age of the culture. In HeLa cell cultures, mycoplasmata were found attached to plasma membranes of cells; in sections, individual mycoplasmata were often aligned in radial apposition to the membranes. Mycoplasmata were not found intracellularly. The three-dimensional morphology of spherules was examined by the critical point method and by scanning electron microscopy. Both methods revealed lobulated forms, ring-shaped forms, and star-shaped forms. Treatment of the spherules with crude porcine pancreatic lipase effectively released large numbers of free organisms. Phosphotungstic acid preparations of these uncentrifuged forms revealed a morphology in agreement with the other methods used. Lobulated ring forms with "beaded" filaments were prominent. In respect to morphology, M. pneumoniae under our conditions resembles that of the type species M. mycoides.

Identification of Mycoplasmatales: procedures for both characterization and purification

Procedures with potential value for identification and purification of Mycoplasma were applied to over 240 cultures representing 11 of the 12 known avian serotypes. Growth was tested at pH 5.5 and 9.5, at 25 and 42 C, in serum-free media, and in the presence of (i) 1% bile salts, (ii) 3% NaCl, and (iii) 0.02% methylene blue. One avian Mycoplasma serotype grew in broth containing 1% bile salts. Two of 11 avian serotypes were resistant to 0.02% methylene blue. A number of Mycoplasma strains grew at 42 C or in a pH 9.5 medium. Usefulness of these procedures for purifying cultures of Mycoplasma is discussed.

T-strains of mycoplasma and nongonococcal urethritis

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Polyacrylamide gel identification of bacterial L-forms and Mycoplasma species of human origin

Polyacrylamide gel electrophoretic patterns of acidified phenol extracts prepared from whole cells can be used for the identification of bacterial L-forms and Mycoplasma species of human origin. Ten human Mycoplasma serotypes and eight L-forms belonging to five different genera were studied. The gel patterns were sufficiently distinct and reproducible that it was possible not only to identify L-forms at the genus level (group with streptococci) and different Mycoplasma serotypes but also to differentiate between the two of them. The parentage of L-forms of Streptobacillus moniliformis L1, Listeria monocytogenes, Streptococcus MG, and Staphylococcus aureus Smith strain was established by relating their gel patterns directly to parent bacteria. It was found that an L-form designated S. moniliformis An (ATCC 14220) was actually an L-form of Proteus. In addition, it was shown electrophoretically that no relationship existed between the Streptococcus MG L-form and M. pneumoniae. The applicability of this method as a diagnostic and taxonomic tool for the differentiation of L-forms and mycoplasmas is discussed.

Antigenic differences within the species Mycoplasma hominis

Membrane and soluble fractions of one genital and two oral strains of Mycoplasma hominis were compared by immunodiffusion and polyacrylamide gel electrophoresis. Differences were demonstrated between the membrane antigens of the three strains by immunodiffusion, and the membrane proteins also gave dissimilar patterns in polyacrylamide gel electrophoresis. The soluble fractions gave identical lines in immunodiffusion tests and similar patterns in polyacrylamide gel electrophoresis.When the strains were cross-titrated in metabolic inhibition (MI) and indirect haemagglutination (IHA) tests, statistical analysis of the results revealed significant differences between the strains. Previously, growth-inhibition, MI and IHA activity was shown to be associated with the membrane antigens of M. hominis, so the intraspecies differences revealed by MI and IHA correlate with the differences in the membrane antigens demonstrated by immunodiffusion. Growth-inhibition tests, which might also have been expected to show intraspecies differences, did not do so, probably because of the insensitivity of the test. In contrast to MI and IHA, complement-fixation (CF) tests revealed a high degree of relatedness between the strains. This is consistent with the observation that the soluble antigens of M. hominis participate in the CF reaction, and that the soluble antigens of different strains are identical in immunodiffusion tests.

Electrophoretic analysis of cell proteins of T-strain mycoplasmas isolated from man

Electrophoretic patterns of the cell proteins of 12 T-strain mycoplasmas isolated from man showed a remarkable similarity. This finding suggests that these strains are genetically closely related and supports their classification in a single species.

Large-quantity production of chicken embryo tracheal organ cultures and use in virus and mycoplasma studies

Chicken tracheal organ cultures were made from embryos which were 19 to 20 days old. Transversely cut rings of trachea were placed in screw-capped tissue-culture tubes with Eagle's-N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid (HEPES) medium and incubated in roller drums. The method had advantages over other organ culture systems in that these cultures were prepared in numbers similar to conventional tissue cultures, ciliary activity was quickly and accurately evaluated, and contamination occurred less frequently than with organ cultures in petri dishes. Ciliary activity persisted for at least 1 month when the medium was changed at 5-to 7-day intervals and for 10 to 15 days without a change. Infectious bronchitis virus stopped ciliary movement, and this effect was used as a basis for titrating the virus and for determining the neutralizing capacity of immune mouse ascitic fluid. Twenty-four Mycoplasma strains were tested. Organisms of 17 strains, both avian and mammalian, multiplied in the organ cultures, and 7 strains, belonging to the species M. gallisepticum and M. mycoides var. capri, inhibited ciliary activity.

Proposal for classifying strain PG-24 and related canine mycoplasmas as Mycoplasma edwardii sp. n

Mycoplasmas recovered recently from dogs were found unrelated to three classified canine Mycoplasma serotypes but were similar in biological and serological properties to a Mycoplasma strain (C21, PG-24) isolated 18 years earlier. It is proposed that strains with the characteristics described be designated Mycoplasma edwardii sp. n.

Three-dimensional morphology, ultrastructure, and replication of Mycoplasma felis

The morphology and replication of Mycoplasma felis in relation to growth phase in culture were studied by electron microscopy. The organisms showed 1.0 to 1.45-hr doubling times with typical bacterial-type growth curves when grown in dialysate broth supplemented with horse serum. Organisms were fixed for electron microscopy by using Veronal acetate-buffered 0.8% OsO(4) (pH 6.1) in 20% sucrose. The morphology of exponential-phase organisms differed markedly from that of stationary or death-phase organisms, which were essentially large round forms with either dispersed or abnormally aggregated cytoplasm. Plasticine models prepared from serial sections of organisms in exponential phase showed the organisms to be either disc-shaped, triangular, horseshoe-shaped, or multilobular. A central "hole" was frequently present in these structures and could be visualized in the lobular forms as an interconnecting circular membrane. The inner surface of this membrane often showed contact with a small membranous body about 0.12 mum in diameter. The significance of this body is unknown. The morphology of the various shapes was confirmed by using the phosphotungstic acid and critical point methods. When the ratios of the various forms in exponential-phase cultures were determined, it was found that a replication sequence could be proposed which accounted for not only the volume increase required to accommodate deoxyribonucleic acid (DNA) replication but also the distribution of that DNA. Although it is likely that DNA replication in M. felis is a binary process, it appears that the mechanism for production of new cells need not be a binary process.

Zone electrophoresis of enzymes in bacterial taxonomy

The electrophoretic mobilities in starch gels have been determined for eight enzymes in extracts of representative cultures of members of the family Enterobacteriaceae. These values were compared with each other and with those obtained from certain bacteria not in this family. The migrations of the eight enzymes were virtually identical for each of eight strains of Escherichia coli and for two species of Shigella. A number of these enzymes appeared to be identical in other organisms believed to be closely related to E. coli (Salmonella), and the number of differences increased in organisms which appeared to have lesser degrees of relatedness by other criteria (deoxyribonucleic acid base compositions, overall similarity).