Serological comparison of ten glycolytic Mycoplasma species

Immunogenicity of Mycoplasma pneumoniae

The immunogenicity of Mycoplasma pneumoniae for New Zealand white female rabbits was studied by using an immunization scheme which employed initial intramuscular immunization with vaccine in incomplete Freund adjuvant followed 3 weeks later by a series of five intravenous injections of fluid vaccine. Small doses of immunogen (15 to 150 mug of mycoplasmic protein per rabbit) gave rise to sera which contained antilipid complement-fixing antibody, produced one to three precipitin lines, but gave poor growth-inhibition on agar. Larger doses of immunogen (1.5 to 15 mg per rabbit) gave rise to sera which gave higher antilipid complement-fixing titers, four to eight precipitin lines, and good growth-inhibition. Doses smaller than 15 mug per rabbit failed to give rise to detectable antibody. Growth-inhibiting antibody was produced later than the other antibodies. The number of precipitin lines was controlled more critically by the quality of the antisera, as determined by the amount of immunogen, than by the quantity of serological test antigen. All sera which gave any precipitin lines produced a common precipitin line which stained for lipid.

Increased uptake and retention of rhodamine 123 by mitochondria of old human fibroblasts

Binding of the fluorescent dye R123 by a variety of mammalian cells has been shown to be dependent on the high transmembrane potential maintained in functional mitochondria. Recent studies in our laboratory have shown that old human fibroblasts (HF) bind and retain more R123 than young HF. In an effort to determine whether this difference in R123 uptake indeed reflected a difference in mitochondrial transmembrane potential, drugs known to disrupt the transmembrane potential of mitochondria were used to monitor the R123-mitochondria interaction of young and old HF. Distinct differences indicating that old HF maintain a higher mitochondrial transmembrane potential were observed. More significantly, perhaps this difference reflects an age-related change(s) in the structure and/or function of mitochondria.

Flow-cytometric analysis of mitochondria-associated fluorescence in young and old human fibroblasts

Rhodamine 123 fluorescence in populations of young and old human fibroblasts was analysed and quantified with a fluorescence-activated cell sorter (FACS). Old fibroblasts exhibited a higher mean relative fluorescence than young fibroblasts. Moreover, two distinct subpopulations were evident in the fluorescence distributions of old cells--but not in those of young cells.

Induction of DNA polymerase alpha in senescent cultures of normal and Werner's syndrome cultured skin fibroblasts

DNA polymerase alpha activity was determined following serum stimulation of early and late passages of human diploid fibroblast-like (HDFL) cultures derived from apparently normal donors (two strains) and from a patient with Werner's syndrome (one strain). Induction of this enzyme was observed in both low passage, actively proliferating cultures and in postmitotic "senescent" cultures from all three strains. The maximal polymerase activity of early and late passage cells of each strain were nearly identical when normalized to the number of cells present. However, the activity of the enzyme was observed to be significantly lower in late passage cultures when normalized to total protein content apparently because of enlargement of the senescent cells. The behavior of Werner derived cells was similar to that of the normal cells. The induction of DNA polymerase alpha in senescent cultures indicates that they retain the capacity to carry out some complex metabolic responses to mitogen stimulation. In addition, these results suggest the possibility that dilution of DNA polymerase alpha and/or other DNA replication factors may play a role in the onset or maintenance of the postmitotic state in the enlarged senescent HDFL cells.

Epidemiologic and immunologic studies in processors of the king crab

Following the report of ten cases of respiratory illness in processors of frozen king crab, we investigated the conditions of work and the pulmonary and immunologic status of the workers in three crab-processing and one fish-packing (control) plant. Pulmonary function was measured before and after work, and skin tests were performed in subgroups matched for age, sex, and duration of current employment. The antibody response to king crab antigens was examined in sera from the subgroups and another (unrelated) control group. Extracts of crab meat, shell, and processing dust were used for skin testing and precipitin detection. FEV1, FVC, and MEFR decreased during the day in two crab processors, and precipitins were evident in sera from nine, but findings were normal in the fish packers. Crab meat elicited the strongest response, with multiple precipitin bands in some cases. Control sera showed no reaction. There was correlation between serology, results of skin tests, and symptoms. It is concluded that the inhalation of aerosolized crab antigen(s) may cause respiratory symptoms and can cause immunologic effects similar to those caused by other occupational respiratory allergens. We recommend preplacement and periodic medical examination of workers in crab-processing plants, improved ventilation in processing areas, and programs to discourage smoking.

I-E/I-C region-associated induction of murine gamma interferon by a haplotype-restricted polyclonal T-cell mitogen derived from Mycoplasma arthritidis

Cell-free supernatants from cultures of Mycoplasma arthritidis induced significant levels of interferon when cocultured with murine splenic cells. On the basis of physicochemical characteristics and antibody neutralization studies, the antiviral substance was identified as gamma interferon. Use of inbred and congenic mouse strains established that splenic cells from mice expressing the H2k and H2d haplotypes produced interferon in response to M. arthritidis culture supernatants, but those from mice with H2b and H2q haplotypes did not. Further studies with recombinant mouse strains established that interferon induction by the mycoplasma supernatant was associated with the haplotype expressed at the I-E/I-C subregion of the murine major histocompatibility complex. The specificity seen for interferon induction was identical with that reported earlier for induction of cytotoxic lymphocytes and for lymphocyte proliferation in response to the mitogen. All of these reactions appear to be dependent upon binding of the mitogen to specific I-E/I-C region-coded products present on splenic cell surfaces. The observations presented introduce the concept that microbial mitogens or their lymphokine products might modify immune responses and defense mechanisms of the naive host in a genetically restricted manner.

Evidence for differences in the mechanism of cell cycle arrest between senescent and serum-deprived human fibroblasts: heterokaryon and metabolic inhibitor studies

It has previously been shown that serum-deprived, early passage quiescent human diploid fibroblastlike (HDFL) cells are able to inhibit cycling cells from entry into DNA synthesis upon cell fusion. We have found that the degree of inhibition of DNA synthesis in the heterokaryon correlates with the duration of serum deprivation, which is consistent with the suggestion that serum-deprived cells may enter progressively deeper stages of G0 as they increase their time in quiescence. In contrast to fusions with senescent cells, in heterokaryons between serum-deprived early passage and cycling young cells transient inhibition of protein synthesis with cycloheximide or inhibition of RNA synthesis with 5-6-dichloro-1-beta-D-ribofuranosyl benzimidazole (DRB) did not stimulate nuclear [3H]-thymidine incorporation. These results suggest that differences may exist in the mechanisms responsible for inhibiting cell cycle progression in senescent vs early passage quiescent HDFL cells.

Inhibition of DNA synthesis in young cycling human diploid fibroblast-like cells upon fusion to enucleate cytoplasts from senescent cells

Previous studies have demonstrated that upon fusion with actively cycling human diploid fibroblast-like (HDFL) cells, senescent HDFL are capable of inhibiting the young nucleus from entry into DNA synthesis (Norwood et al. (1974) [10]; Rabinovitch et al. (1980) [1]). These studies have been interpreted as evidence in favor of the existence of cell cycle inhibitors in senescent cells. Enucleate cytoplasts derived from senescent HDFL cells are also capable of inhibiting the young nucleus from entry into DNA synthesis upon fusion with whole cycling HDFL cells. In contrast, no inhibition was observed in fusions between enucleate young cells and whole cycling cells. These results provide evidence for transmissible cell cycle-inhibitory factors in the cytoplasm of senescent cells.

Medium components adsorbed to mycoplasmal cells

Washed cells of Mycoplasma pneumoniae mixed with complete Freund's adjuvant were capable of producing lethal anaphylactic shock in mice when injected repeatedly into the foot pad. The causative agent is associated with horse serum contained in the culture medium but cannot be removed from mycoplasmal cells by repeated washing with phosphate buffered saline. Mycoplasmas grown in medium containing rabbit serum had a similar effect. No lethal anaphylaxis occurs when M. pneumoniae is injected without adjuvant.

Evidence that a critical threshold of DNA polymerase-alpha activity may be required for the initiation of DNA synthesis in mammalian cell heterokaryons

The specific activity of DNA polymerase (90% alpha) was determined in nine "neoplastoid" cell lines (Martin and Sprague, 1973) and in three different strains of HDF (human diploid fibroblast-like cells), all examined in logarithmic phases of growth. This was compared to the ability of each cell type to "rescue" (reinitiate DNA synthesis in) senescent HDF cells subsequent to polyethylene glycol-mediated cell fusions. A sharp "threshold" value of DNA polymerase activity was observed below which reinitiation of DNA synthesis in heterokaryons with senescent HDF does not occur. This threshold was especially obvious when the specific activity of DNA polymerase (p moles dTTP incorporated per mg protein or per cell) was divided by the percent of S-phase cells present in each culture as determined by flow microfluorometry. Our results indicate that the specific activity of DNA polymerase-alpha (or some other factor tightly coregulated with it) in "recessive" cell types (those unable to rescue senescent cells) is only about two times this theoretical "threshold" value, and that fusion of recessive cell types to senescent HDF cells reduces the specific activity in the heterokaryon to below this minimum, thus preventing the cells from entering S phase.

Evidence for endogenous polypeptide-mediated inhibition of cell-cycle transit in human diploid cells

Previous studies have shown that the senescent phenotype is dominant with respect to DNA synthesis in fusions between late passage and actively replicating human diploid fibroblasts. Brief postfusion treatments with the protein synthesis inhibitor cycloheximide (CHX) or puromycin have been found to significantly delay (by 24-48 h) the inhibition of entry into DNA synthesis of young nuclei in heterokaryons after fusion with senescent cells. A significant fraction of the senescent nuclei incorporated tritiated thymidine in CHX-treated heterokaryons. The optimal duration of exposure to CHX was 1-3 h immediately after fusion, although treatments beginning as late as 9 h after fusion elevated the heterokaryon labeling index. Prefusion treatments with CHX were without a significant effect. These results are consistent with the interpretation that regulatory cell cycle inhibitor(s) which are dependent upon protein synthesis may be present in heterokaryons between senescent and actively replicating cells.

Growth inhibition and morphologic modulation of human fibroblastlike cells by erythromycin

In vitro exposures of mass cultures and clones of human diploid fibroblastlike cells to erythromycin, in concentrations of 50 to 400 micrograms/ml, results in increasing degrees of growth inhibition and augmented cell volume, with a shift toward larger proportions of cells of the epithelioid type and fewer of the fibroblast type. These alterations were reversed upon subculture in the absence of the antibiotic.

Systematic growth studies, cocultivation, and cell hybridization studies of Werner syndrome cultured skin fibroblasts

The growth of 20 independently derived skin fibroblastlike (FL) cell strains from three individuals with Werner syndrome (adult progeria) was compared with the growth of ten FL cell strains from normal individuals. Population growth rates and total replicative life spans of Werner syndrome strains averaged 53% and 27%, respectively, of the growth rates and life spans of non-Werner strains. In the first few passages, four Werner syndrome strains demonstrated population growth rates in the low normal range, but the longest-lived Werner syndrome strain had only 75% of the total replicative potential of the shortest-lived normal strain. Exponential growth rates, cloning efficiencies, and saturation densities of Werner strains were also reduced, whereas cell attachment was normal. Viable cells (identified by dye exclusion) were maintained in post-replicative Werner syndrome and control cultures for periods of at least 10 months; there was no evidence of accelerated post-replicative senescence of cell death of Werner syndrome FL cells. Cocultivation of Werner syndrome and normal strains did not influence population growth rates of either strain. Two proliferating hybrid clones were obtained from fusions of normal and Werner syndrome FL cell strains and these hybrids displayed the reduced growth potential typical of Werner syndrome FL cells. These studies confirm that low growth rate and sharply reduced replicative life span are characteristic of cultured skin FL cells from patients with Werner syndrome, and they suggest that these characteristics are not affected by complementation with non-Werner FL cells.

Selective elimination of proliferating cells in human diploid cell cultures by treatment with BrdU, 33258 Hoechst and visible light

We have attempted to obtain pure populations of postmitotic cells from cultures of human diploid fibroblasts by the selective elimination of replicating cells. The selective system consists of treating cultures with 5-bromodeoxyuridine (5-BrdU) followed by exposure to the fluorescent dye 33258 Hoechst and irradiation with visible light. The percentage of survivors after the combined treatment was observed to be inversely proportional to the pretreatment [3H] thymidine labeling index of the culture. The post-treatment labeling indices, determined on the basis of the number of cells plated prior to the initiation of treatment, was higher in late passage cultures. Even after prolonged exposure to 5-BrdU (10 days), a small fraction of cells in early passage human fibroblast-like cultures was capable of incorporating [3H] thymidine. In contrast, actively replicating cells could be completely eliminated from HeLa cultures in this selective system. Studies with [3H] BrdU indicated that the cells incorporating this analog are preferentially killed. These observations suggest that human diploid cell cultures contain a subpopulation of very slowly cycling or transiently noncycling cells.

Cellular aging in Werner's syndrome: a unique phenotype?

Werner's syndrome is commonly regarded as a model for the study of premature aging. There are, however, a variety of clinical and pathologic anatomical features that clearly distinguish it from aging in normal individuals. In this paper we report on in vitro cytogenetic and cell fusion studies that indicate cultured fibroblast-like cells derived from Werner patients differ from cells of normal donors. Despite these discordances with "natural" aging, however, Werner's syndrome, like several other "segmental progeroid syndromes," may prove useful for the investigation of selected aspects of the aging process and of age-related diseases.

Evidence for clonal attenuation of growth potential in HeLa cells

The growth of primary clones and serial subclones of HeLa cells and of diploid human fibroblast-like cells were compared both in the presence and absence of feeder layers; the latter had no significant effects upon the results. Clones and subclones of both cell types displayed great heterogeneity in growth rates, typically with a bimodality of growth distributions. Serial passages of clones selected on the basis of superior rates of proliferation showed attentuation of growth potentials; the extent of such attentuations was much less in the case of HeLa cells, suggesting at least one possible basis for the differences in long-term growth potential between these two classes of cell lines.

Differences in incorporation of nucleic acid bases and nucleosides by various Mycoplasma and Acholeplasma species

Eight species representative of the serological diversity of the Mycoplasmatales were tested for their ability to incorporate radiolabeled nucleic acid precursors into acid-insoluble material. Cultures in complex growth medium were centrifuged and resuspended in minimal essential medium (Eagle). For Acholeplasma laidlawii, labeling occurred mainly during the first 4 h of incubation, with substrate saturation at 20 micron. All organisms tested incorporated uracil, adenine, and guanine; none incorporated cytosine. Thymine was incorporated only by bovine group 7, Mycoplasma putrefaciens, and Mycoplasma pneumoniae (strain 3546), but deoxynucleosides enhanced thymine incorporation in A. laidlawii, Mycoplasma gallisepticum, M. pneumoniae (strain AP-164), and Mycoplasma hyorhinis. Nucleoside incorporation (adenosine, guanosine, uridine, cytidine, and thymidine) was not observed for the arginine-utilizing species, Mycoplasma hominis and Mycoplasma arginini, whereas all other organisms tested incorporated nucleosides. The incorporation pattern provides additional metabolic evidence to support the biochemical and antigenic diversity of these organisms. The recognition of differences in incorporation of nucleic acid precursors is important not only to the specific labeling of these organisms, but also to the study of metabolism and transport.

Effect of urea concentration on growth of Ureaplasma urealyticum (T-strain mycoplasma)

The effect of urea on growth of Ureaplasma urealyticum type VIII was studied by cultivating the organisms in a dialysate broth, prepared from soy peptone and autoclaved yeast, supplemented with 5% dialyzed horse serum, 100 mM 2-(N-morpholino)ethane sulfonic acid buffer (pH 5.75), and defined amounts of urea. Without urea, growth did not occur. Total growth was directly related to urea concentration. The least amount of urea that supported growth was 0.032 mM, which resulted in 3 x 10(4) colony-forming units per ml. The maximum yield of organisms, 8.0 x 10(7) colony-forming units per ml, was observed at 32 mM urea. Growth was limited not only by urea concentration, but also by the buffer capacity of the medium. The maximum amount of 2-(N-morpholino)ethane sulfonic acid buffer that could be employed was 100 mM; at higher concentrations, growth was inhibited. The yield of U. urealyticum was small even in medium with 32 mM urea and 100 mM 2-(N-morpholino)ethane sulfonic acid buffer: 0.63 mg of protein per liter of culture containing 5 x 10(10) total colony-forming units. The molar growth yield was 20 mg of protein per mol of urea. The growth rate was also a function of urea concentration. Generation times ranged from 8 h at 0.032 mM urea to 1.6 h at 3.2 mM urea, where the substrate level was saturating. The K(s) value for growth was 2.0 x 10(-4) M urea. Thus, urea is a growth-limiting factor for U. urealyticum, but remarkably large amounts of this substrate are required.

Dimethyl sulfoxide enhances polyethylene glycol-mediated somatic cell fusion

The efficiency of fusion of human diploid cells by polyethylene glycol was greatly enhanced by addition of dimethyl sulfoxide. The extent of fusion was directly proportional to the concentrations of both of these compounds. At all except the highest concentrations, cell loss was moderate to minimal and perturbation of cell cycle function as measured by [3H] thymidine labeling indices and mitotic indices was minimal in the surviving cells. This technique is potentially useful for heterokaryon studies as well as for the isolation of hybrids of mammalian somatic cells.

Enzymatic synthesis of two fucose-containing glycolipids with fucosyltransferases of human serum

Lacto-N-neotetraosylceramide incubated with human serum fucosyltransferase preparations gave rise to two fucoglycolipids. The faster migrating fucoglycolipid I on the basis of its thin-layer chromatographic mobility, susceptibility to alpha(1 leads to 2) fucosidase from Trichomonas foetus, radio-immunoprecipitation with Ulex europeus lectin and studies with Oh (Bombay) sera was identified as H-active glycolipid (H-I). The most probable structure of fucoglycolipid II should be that with fucose linked alpha(1 leads to 3) to N-acetylglucosamine. Lactosylceramide, ceramide trihexoside and globoside were not substrates for human serum fucosyltransferases. Lacto-N-neotetraosyl ceramide served as a fucose acceptor for all serum preparations tested while asialoganglioside was a substrate only when serum preparations containing H-gene dependent alpha-2-L-fucosyltransferase were used. With asialoganglioside only one radioactive reaction product was formed.

Role of arginine deiminase in growth of Mycoplasma hominis

Arginine has been considered as the major energy source of nonglycolytic arginine-utilizing mycoplasmata. When three strains of Mycoplasma arginini, and one strain each of Mycoplasma arthritidis, Mycoplasma fermentans, Mycoplasma gallinarum, Mycoplasma gallisepticum and Mycoplasma hominis were grown in the medium with high arginine concentration (34 mM) compared with low arginine (4 mM), both the protein content of the organisms and the specific activity of arginine deiminase increased. M. fermentans, the one arginine-utilizing species included in the survey which is also glycolytic, showed an increase in protein content but no increase in specific activity of the enzyme. The glycolytic non-arginine-utilizing M. gallisepticum did not show an increase in either parameter. The Km for arginine deiminase from crude cell extracts was 1.66 X 10(-4)M. The enzyme demonstrated a hyperbolic activation curve subject to substrate inhibition and was not affected by the presence of L-histidine. When mycoplasmic protein and arginine deiminase were determined for M. hominis under aerobic and anaerobic conditions, aerobically grown cells exhibited no detectable enzymatic increases until late in log phase. Higher levels of arginine deiminase were observed earlier in the anaerobic growth cycle. The rate of 14CO2 evolution from [guanido-14C]arginine was not altered in arginine-supplemented cells compared with cells grown in low arginine. In addition, CO2 production did not parallel increased arginine deiminase activity. These observations argue that arginine is used only as an alternate energy source in these organisms.

A serologic variant of Mycoplasma hyorhinis recovered from the conjunctiva of swine

In an examination of conjunctival samples from 40 piglets for mycoplasmas, 17 isolates were obtained. Eight could be identified as Mycoplasma hyorhinis, three as Mycoplasma flocculare, and one as Acholenlasma sp. Five strains were not readily identifiable, but together with two previously recovered strains they were found to represent a distinct serogroup. All seven strains were glucose and phosphatase positive. Incubation in a CO₂-enriched atmosphere led to enhancement of the growth on solid medium. The serogroup was serologically related to M. hyorhinis, but not to a number of other glucose fermenting species of mycoplasma, and it may therefore be regarded as a new subspecies of M. hyorhinis.

Canine mycoplasmas: serological studies of type and reference strains, with a proposal for the new species, Mycoplasma opalescens

The type and reference strains of all Mycoplasma species or "serogroups" presently known to occur in dogs were compared serologically. Tests of growth inhibition and metabolism inhibition as well as indirect immunofluorescence tests did not disclose any cross reactions. Examination by double immunodiffusion revealed at least one antigen specific for each strain tested. In addition, the common antigens were found within the glucose fermenting group and within the arginine metabolizing group of Mycoplasma strains, respectively. No antigens were shared by these groups. The arginine positive strain MH5408, serogroup D was found to differ serologically from all other arginine positive Mycoplasma species. Serogroup D is therefore a new species for which the name Mycoplasma opalescens is proposed. The type strain is MH5408 (ATCC 27921 and NTCC 10149). Finally, serological data are presented which relate strain HRC689 to M. mycoides.

Reinitiation of DNA synthesis in senescent human fibroblasts upon fusion with cells of unlimited growth potential

Postreplicative, "senescent" human fibroblasts were fused to HeLa or to SV-40 transformed human fibroblasts with Sendai virus. DNA synthesis was reinitiated in senescent nuclei in a high proportion of the heterodikaryons. The [3H]thymidine labeling index of senescent fibroblast nuclei in heteropolykaryons was a function of the ratio of HeLa to senescent nuclei.

Serological comparison of five arginine-utilizing Mycoplasma species by two-dimensional immunoelectrophoresis

Five arginine-utilizing, nonglycolytic Mycoplasma species were compared serologically by two dimensional immunoelectrophoresis. The survey included: Mycoplasma hominis, Mycoplasma arthritidis, Mycoplasma gateae, Mycoplasma gallinarum, and three strains of Mycoplasma arginini. Although the M. arginini strains showed strong cross-reactions, each strain produced a different antigenic profile which was distinct and which indicated significant antigenic differences between strains. The M. arginini strains showed strong relationships with M. gateae; lesser cross-reactions were observed with other strains. Common antigens were demonstrable in the entire group. When all these species were compared with a glycolytic species, Mycoplasma gallisepticum, no cross-reactions were observed. Two-dimensional immunoelectrophoresis was a far more sensitive technique than double-immunodiffusion since as many as 20 components could be resolved.

Dominance of the senescent phenotype in heterokaryons between replicative and post-replicative human fibroblast-like cells

In heterokaryons between senescent and young diploid fibroblast-like cells, dominance of the former with respect to nuclear DNA synthesis (incorporation of [(3)H]thymidine) was demonstrated. For identification of the respective partners, double-layer autoradiography was used after the old cells were labeled with [(3)H]methionine and the young cells were labeled with [(14)C]thymidine. Synchrony of nuclear labeling (i.e., all nuclei in a cell labeled with [(3)H]thymidine) was observed in the majority of di- and polykaryons during the second and third of three 24-hr periods of labeling with [(3)H]thymidine. The results are compatible with either terminal differentiation or error theories of clonal senescence.

Differences in arginine requirement for growth among arginine-utilizing Mycoplasma species

The essentiality of arginine for initiation of growth of arginine-utilizing, nonglycolytic Mycoplasma species from small populations was studied by growing the organisms in a semisynthetic medium proven to be free from arginine by chemical and biological assays. Initiation of growth of two strains of M. arginini did not require arginine, whereas another strain of M. arginini required 4 mM arginine, as did M. gallinarum. M. hominis grew in 0.4 mM arginine. A species which utilizes both arginine and glucose, N. fermentans, did not require arginine but did require glucose for growth. When mycoplasmata were grown in human heteroploid cell cultures employing medium free from arginine but supplemented with citrulline, similar results were obtained: two M. arginini strains grew in the absence of arginine, whereas growth of M. gallinarum and M. hominis and a third M. arginini strain was dependent on arginine even though mammalian cells were present. The arginine deiminases were heterogeneous serologically: antisera to M. hominis and M. arginini showed reciprocal inhibition of their enzymes but did not inhibit arginine deiminase from M. gallinarum. Antiserum to M. gallinarum inhibited only M. gallinarum enzyme.

Clonal selection, attenuation and differentiation in an in vitro model of hyperplasia

Observations of the growth kinetics and morphologies of clones and subclones of diploid human skin fibroblast cultures lead to the working hypothesis that these cells, presumably like their counterparts in healing wounds, constitute a differentiating system. There is attenuation of the growth of serial clones, with continual selection for more vigorous stem cells. The latter segregate daughter cells of varying growth potential, including a class of cells which may be regarded as terminally differentiating; we propose that such cells may be histiocytes or macrophages. These studies a) demonstrate extensive epigenetic heterogeneity in fibroblast cultures, b) suggest that hyperplastic foci may be monoclonal or oligoclonal, c) rule out a simple biologic clock mechanism as an explanation of clonal senescence, d) suggest a new approach to the analysis of various inborn errors of metabolism, such as Werner's Syndrome.

Correlation of circulating capsular polysaccharide with bacteremia in pneumococcal pneumonia

Immunoelectroosmophoresis with rabbit anticapsular antibody was used to detect type-specific pneumococcal polysaccharide in serum from bacteremic patients with pneumococcal pneumonia. The test could detect as little as 0.1 to 1.0 mug per ml or 0.2 to 2 ng per test of polysaccharide from types 1, 2, 3, 4, 5, 8, 12, and 18, and its sensitivity was 10 times that of double immunodiffusion. Although antigen could be detected by double immunodiffusion with types 7 and 14, no antigen could be detected by immunoelectroosmophoresis. Types 7 and 14 polysaccharides were found to be positively charged, whereas the other polysaccharides were negatively charged. Forty-six patients with pneumonia were selected for study because pneumococci corresponding to those types where the test was known to work had been isolated from blood or the respiratory tract. Antigenemia correlated strongly with bacteremia: 12 of 20 bacteremic patients with pneumonia showed antigenemia, whereas 26 patients negative for bacteremia did not show circulating antigen detectable with antisera against the pneumococcal type isolated from the respiratory tract. The apparent concentration of circulating polysaccharide ranged from 0.1 to 100 mug per ml of serum, and the concentration did not appear to diminish appreciably in 10 to 15 days. Three of 12 patients with antigenemia died, and two of these had the highest levels of circulating antigen observed.

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.

Immunogenicity of Mycoplasma pneumoniae glycolipids: a novel approach to the production of antisera to membrane lipids

The glycolipid haptens of Mycoplasma pneumoniae were bound to membrane proteins of acholeplasma laidlawii (formerly Mycoplasma laidlawii) by reaggregation. This process consisted of the solubilization of lipid-depleted A. laidlawii membranes and M. pneumoniae glycolipids in 20 mM sodium dodecyl sulfate, and dialysis of the mixed solutions against 20 mM Mg(2+). The hybrid reaggregate, collected by centrifugation, was highly immunogenic in rabbits, eliciting the production of a high titer of antibodies that fixed complement with the purified glycolipids and inhibited the metabolism of M. pneumoniae cells. The free glycolipids, or their mixture with A. laidlawii proteins, were much less effective in stimulating these antibodies. The antibodies to the hybrid reaggregate agglutinated M. pneumoniae cells and inhibited their ability to absorb erythrocytes, which indicates that at least some of the serologically-active glycolipids are exposed at the outer membrane surface. The ability to bind selected membrane lipids to membrane proteins of a serologically unrelated species provides a new tool for producing antibodies to lipid haptens.

Heterogeneity among strains of Mycoplasma granularum and identification of Mycoplasma hyosynoviae, sp. n

Twelve filtrable, pleomorphic organisms isolated from swine joints and respiratory tracts had typical colonial and microscopic characteristics of mycoplasmas. They resisted penicillin and did not revert to cell wall-producing bacterial forms in media devoid of bacterial inhibitors. The morphological and growth characteristics of these mycoplasmas were similar to those described previously for Mycoplasma granularum. However, a new name, M. hyosynoviae, is proposed for them since they differed biologically, serologically, and electrophoretically from the prototype strain of M. granularum. M. hyosynoviae required sterols, was stimulated by gastric mucin, and metabolized arginine; however, it did not metabolize urea, ferment glucose, or reduce tetrazolium. The organism produced "film and spots" on horse serum-supplemented medium and produced alpha hemolysis of guinea pig and sheep erythrocytes; however, it did not digest serum, produce phosphatase, or hemadsorb guinea pig or swine erythrocytes. M. hyosynoviae was distinguished from three other swine mycoplasmas, M. granularum, M. hyorhinis, and M. laidlawii, by means of acrylamide gel electrophoresis, growth inhibition, metabolic inhibition, and immunodiffusion techniques. It was also serologically and electrophoretically distinct from 13 additional non-swine mycoplasmas which require sterols and metabolize arginine.

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.

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.