Faculty Opinions recommendation of Intrastrain heterogeneity of the mgpB gene in Mycoplasma genitalium is extensive in vitro and in vivo and suggests that variation is generated via recombination with repetitive chromosomal sequences.

2006 ◽  
Author(s):  
Jeffrey Lawrence
Keyword(s):  
Mycoplasma Genitalium ◽  
Chromosomal Sequences

scholarly journals Intrastrain Heterogeneity of the mgpB Gene in Mycoplasma genitalium Is Extensive In Vitro and In Vivo and Suggests that Variation Is Generated via Recombination with Repetitive Chromosomal Sequences

2006 ◽  
Vol 74 (7) ◽  
pp. 3715-3726 ◽  
Author(s):  
Stefanie L. Iverson-Cabral ◽  
Sabina G. Astete ◽  
Craig R. Cohen ◽  
Eduardo P. C. Rocha ◽  
Patricia A. Totten
Keyword(s):  
Reproductive Tract ◽  
Natural Infection ◽  
Mycoplasma Genitalium ◽  
Infected Woman ◽  
Expression Site ◽  
Tract Disease ◽  
Adhesin Protein ◽  
Chromosomal Sequences

ABSTRACT Mycoplasma genitalium is associated with reproductive tract disease in women and may persist in the lower genital tract for months, potentially increasing the risk of upper tract infection and transmission to uninfected partners. Despite its exceptionally small genome (580 kb), approximately 4% is composed of repeated elements known as MgPar sequences (MgPa repeats) based on their homology to the mgpB gene that encodes the immunodominant MgPa adhesin protein. The presence of these MgPar sequences, as well as mgpB variability between M. genitalium strains, suggests that mgpB and MgPar sequences recombine to produce variant MgPa proteins. To examine the extent and generation of diversity within single strains of the organism, we examined mgpB variation within M. genitalium strain G-37 and observed sequence heterogeneity that could be explained by recombination between the mgpB expression site and putative donor MgPar sequences. Similarly, we analyzed mgpB sequences from cervical specimens from a persistently infected woman (21 months) and identified 17 different mgpB variants within a single infecting M. genitalium strain, confirming that mgpB heterogeneity occurs over the course of a natural infection. These observations support the hypothesis that recombination occurs between the mgpB gene and MgPar sequences and that the resulting antigenically distinct MgPa variants may contribute to immune evasion and persistence of infection.

scholarly journals Persistence, Immune Response, and Antigenic Variation of Mycoplasma genitalium in an Experimentally Infected Pig-Tailed Macaque (Macaca nemestrina)

2013 ◽  
Vol 81 (8) ◽  
pp. 2938-2951 ◽  
Author(s):  
Gwendolyn E. Wood ◽  
Stefanie L. Iverson-Cabral ◽  
Dorothy L. Patton ◽  
Peter K. Cummings ◽  
Yvonne T. Cosgrove Sweeney ◽  
...  
Keyword(s):  
Recombinant Protein ◽  
Antigenic Variation ◽  
Immune Escape ◽  
Variable Region ◽  
Mycoplasma Genitalium ◽  
Macaca Nemestrina ◽  
Suitable Model ◽  
Content Type

ABSTRACTMycoplasma genitaliumis a sexually transmitted pathogen associated with several acute and chronic reproductive tract disease syndromes in men and women. To evaluate the suitability of a pig-tailed macaque model ofM. genitaliuminfection, we inoculated a pilot animal withM. genitaliumstrain G37 in the uterine cervix and in salpingeal pockets generated by transplanting autologous Fallopian tube tissue subcutaneously. Viable organisms were recovered throughout the 8-week experiment in cervicovaginal specimens and up to 2 weeks postinfection in salpingeal pockets. Humoral and cervicovaginal antibodies reacting to MgpB were induced postinoculation and persisted throughout the infection. The immunodominance of the MgpB adhesin and the accumulation ofmgpBsequence diversity previously observed in persistent human infections prompted us to evaluate sequence variation in this animal model. We found that after 8 weeks of infection, sequences withinmgpBvariable region B were replaced by novel sequences generated by reciprocal recombination with an archived variant sequence located elsewhere on the chromosome. In contrast,mgpBregion B of the same inoculum propagated for 8 weeksin vitroremained unchanged. Notably, serum IgG reacted strongly with a recombinant protein spanning MgpB region B of the inoculum, while reactivity to a recombinant protein representing the week 8 variant was reduced, suggesting that antibodies were involved in the clearance of bacteria expressing the original infecting sequence. Together these results suggest that the pig-tailed macaque is a suitable model to studyM. genitaliumpathogenesis, antibody-mediated selection of antigenic variantsin vivo, and immune escape.

Identification of 16S rRNA mutations in Mycoplasma genitalium potentially associated with tetracycline resistance in vivo but not selected in vitro in M. genitalium and Chlamydia trachomatis

2021 ◽  
Author(s):  
Chloé Le Roy ◽  
Arabella Touati ◽  
Carla Balcon ◽  
Justine Garraud ◽  
Jean-Michel Molina ◽  
...  
Keyword(s):  
Chlamydia Trachomatis ◽  
16S Rrna ◽  
16S Rrna Gene ◽  
Tetracycline Resistance ◽  
Mycoplasma Genitalium ◽  
Rrna Gene ◽  
Resistant Mutants ◽  
The 16S Rrna Gene

Abstract Objectives Tetracyclines are widely used for the treatment of bacterial sexually transmitted infections (STIs) and recently have been used successfully for post-exposure prophylaxis of STIs in MSM. We investigated the in vitro and in vivo development of tetracycline resistance in Chlamydia trachomatis and Mycoplasma genitalium and evaluated 16S rRNA mutations associated with acquired resistance in other bacteria. Methods In vitro selection of resistant mutants of reference strains of C. trachomatis and M. genitalium was undertaken by serial passage in medium containing subinhibitory concentrations of tetracycline or doxycycline, respectively. The 16S rRNA gene of the two microorganisms was amplified and sequenced at different passages, as were those of 43 C. trachomatis- and 106 M. genitalium-positive specimens collected in France from 2013 to 2019. Results No tetracycline- or doxycycline-resistant strains of C. trachomatis and M. genitalium, respectively, were obtained after 30 serial passages. The tetracycline and doxycycline MICs were unchanged and analysis of the 16S rRNA gene, the molecular target of tetracyclines, of C. trachomatis and M. genitalium revealed no mutation. No mutation in the 16S rRNA gene was detected in C. trachomatis-positive specimens. However, six M. genitalium-positive specimens harboured a mutation potentially associated with tetracycline resistance without known prior tetracycline treatment for patients. Conclusions Tetracyclines did not select in vitro-resistant mutants of C. trachomatis or M. genitalium. However, 16S rRNA mutations either responsible for or associated with tetracycline resistance in other bacteria, including mycoplasma species, were identified in several M. genitalium-positive specimens.

Induction and Differentiation of Dental Epithelium in Vivo and in Vitro

1982 ◽  
Vol 40 ◽  
pp. 142-145
Author(s):  
E. J. Kollar
Keyword(s):  
Connective Tissue ◽  
Oral Mucosa ◽  
Basal Lamina ◽  
Functional Derivatives ◽  
Specific Source ◽  
Dental Epithelium ◽  
Connective Tissue Stroma

The differentiation and maintenance of many specialized epithelial structures are dependent on the underlying connective tissue stroma and on an intact basal lamina. These requirements are especially stringent in the development and maintenance of the skin and oral mucosa. The keratinization patterns of thin or thick cornified layers as well as the appearance of specialized functional derivatives such as hair and teeth can be correlated with the specific source of stroma which supports these differentiated expressions.

Ultrastructural Correlations between Clonal Human Tumor Colonies and in Vivo Neoplasms

1982 ◽  
Vol 40 ◽  
pp. 210-211
Author(s):  
M.J. Murphy ◽  
R.R. Price ◽  
J.C. Sloman
Keyword(s):  
Cultured Cells ◽  
Human Tumor ◽  
Cell Type ◽  
Tumor Mass ◽  
Initial Cell ◽  
Cloning Assay ◽  
Human Tumor Cloning ◽  
The Relationship

The in vitro human tumor cloning assay originally described by Salmon and Hamburger has been applied recently to the investigation of differential anti-tumor drug sensitivities over a broad range of human neoplasms. A major problem in the acceptance of this technique has been the question of the relationship between the cultured cells and the original patient tumor, i.e., whether the colonies that develop derive from the neoplasm or from some other cell type within the initial cell population. A study of the ultrastructural morphology of the cultured cells vs. patient tumor has therefore been undertaken to resolve this question. Direct correlation was assured by division of a common tumor mass at surgical resection, one biopsy being fixed for TEM studies, the second being rapidly transported to the laboratory for culture.

Ultrastructure of melanocyte-keratinocyte interactions and pigment transfer in vitro

1978 ◽  
Vol 36 (2) ◽  
pp. 650-651
Author(s):  
Raul I. Garcia ◽  
Evelyn A. Flynn ◽  
George Szabo
Keyword(s):  
Direct Injection ◽  
Skin Pigmentation ◽  
Freeze Fracture ◽  
Pigment Granule ◽  
Time Lapse ◽  
Ultrastructural Level ◽  
Lanthanum Tracer ◽  
A Cell

Skin pigmentation in mammals involves the interaction of epidermal melanocytes and keratinocytes in the structural and functional unit known as the Epidermal Melanin Unit. Melanocytes(M) synthesize melanin within specialized membrane-bound organelles, the melanosome or pigment granule. These are subsequently transferred by way of M dendrites to keratinocytes(K) by a mechanism still to be clearly defined. Three different, though not necessarily mutually exclusive, mechanisms of melanosome transfer have been proposed: cytophagocytosis by K of M dendrite tips containing melanosomes, direct injection of melanosomes into the K cytoplasm through a cell-to-cell pore or communicating channel formed by localized fusion of M and K cell membranes, release of melanosomes into the extracellular space(ECS) by exocytosis followed by K uptake using conventional phagocytosis. Variability in methods of transfer has been noted both in vivo and in vitro and there is evidence in support of each transfer mechanism. We Have previously studied M-K interactions in vitro using time-lapse cinemicrography and in vivo at the ultrastructural level using lanthanum tracer and freeze-fracture.

In vitro and in vivo polysaccharides assembly: ultrastructural and cytochemical study of growing plant cell wall components.

1978 ◽  
Vol 36 (2) ◽  
pp. 434-435
Author(s):  
D. Reis ◽  
B. Vian ◽  
J. C. Roland
Keyword(s):  
Cell Wall ◽  
Self Assembly ◽  
Plant Cell Wall ◽  
Higher Plants ◽  
Three Dimensional ◽  
Cytochemical Study ◽  
Wall Components

Wall morphogenesis in higher plants is a problem still open to controversy. Until now the possibility of a transmembrane control and the involvement of microtubules were mostly envisaged. Self-assembly processes have been observed in the case of walls of Chlamydomonas and bacteria. Spontaneous gelling interactions between xanthan and galactomannan from Ceratonia have been analyzed very recently. The present work provides indications that some processes of spontaneous aggregation could occur in higher plants during the formation and expansion of cell wall.Observations were performed on hypocotyl of mung bean (Phaseolus aureus) for which growth characteristics and wall composition have been previously defined.In situ, the walls of actively growing cells (primary walls) show an ordered three-dimensional organization (fig. 1). The wall is typically polylamellate with multifibrillar layers alternately transverse and longitudinal. Between these layers intermediate strata exist in which the orientation of microfibrils progressively rotates. Thus a progressive change in the morphogenetic activity occurs.

Probing the ultrastructure of the mitotic and meiotic spindle in eggs: An expeditious approach based on semi-thin (0.25 μm) serial sections

1983 ◽  
Vol 41 ◽  
pp. 552-555
Author(s):  
Conly L. Rieder ◽  
S. Bowser ◽  
R. Nowogrodzki ◽  
K. Ross ◽  
G. Sluder
Keyword(s):  
Small Sample Size ◽  
Small Sample ◽  
Meiotic Spindle ◽  
Serial Sections ◽  
Mitotic Apparatus ◽  
Thin Sections ◽  
Cell Cycles ◽  
Ultrastructural Studies

Eggs have long been a favorite material for studying the mechanism of karyokinesis in-vivo and in-vitro. They can be obtained in great numbers and, when fertilized, divide synchronously over many cell cycles. However, they are not considered to be a practical system for ultrastructural studies on the mitotic apparatus (MA) for several reasons, the most obvious of which is that sectioning them is a formidable task: over 1000 ultra-thin sections need to be cut from a single 80-100 μm diameter egg and of these sections only a small percentage will contain the area or structure of interest. Thus it is difficult and time consuming to obtain reliable ultrastructural data concerning the MA of eggs; and when it is obtained it is necessarily based on a small sample size.We have recently developed a procedure which will facilitate many studies concerned with the ultrastructure of the MA in eggs. It is based on the availability of biological HVEM's and on the observation that 0.25 μm thick serial sections can be screened at high resolution for content (after mounting on slot grids and staining with uranyl and lead) by phase contrast light microscopy (LM; Figs 1-2).

Formation and Structure of Casein Micelles in Lactating Mammary Tissue

1970 ◽  
Vol 28 ◽  
pp. 150-151
Author(s):  
Robert J. Carroll ◽  
Marvin P. Thompson ◽  
Harold M. Farrell
Keyword(s):  
Size Distribution ◽  
G Protein ◽  
Milk Proteins ◽  
Mammary Tissue ◽  
Colloidal System ◽  
Casein Micelles ◽  
The Stability

Milk is an unusually stable colloidal system; the stability of this system is due primarily to the formation of micelles by the major milk proteins, the caseins. Numerous models for the structure of casein micelles have been proposed; these models have been formulated on the basis of in vitro studies. Synthetic casein micelles (i.e., those formed by mixing the purified αsl- and k-caseins with Ca2+ in appropriate ratios) are dissimilar to those from freshly-drawn milks in (i) size distribution, (ii) ratio of Ca/P, and (iii) solvation (g. water/g. protein). Evidently, in vivo organization of the caseins into the micellar form occurs in-a manner which is not identical to the in vitro mode of formation.

Specific Labeling of Protein Domains with Antibody Fragments

1981 ◽  
Vol 39 ◽  
pp. 416-417
Author(s):  
U. Aebi ◽  
L.E. Buhle ◽  
W.E. Fowler
Keyword(s):  
Image Processing ◽  
Specific Protein ◽  
Antibody Fragments ◽  
Supramolecular Organization ◽  
Two Dimensional ◽  
Ordered Structures ◽  
Virus Capsids ◽  
Processing Techniques

Many important supramolecular structures such as filaments, microtubules, virus capsids and certain membrane proteins and bacterial cell walls exist as ordered polymers or two-dimensional crystalline arrays in vivo. In several instances it has been possible to induce soluble proteins to form ordered polymers or two-dimensional crystalline arrays in vitro. In both cases a combination of electron microscopy of negatively stained specimens with analog or digital image processing techniques has proven extremely useful for elucidating the molecular and supramolecular organization of the constituent proteins. However from the reconstructed stain exclusion patterns it is often difficult to identify distinct stain excluding regions with specific protein subunits. To this end it has been demonstrated that in some cases this ambiguity can be resolved by a combination of stoichiometric labeling of the ordered structures with subunit-specific antibody fragments (e.g. Fab) and image processing of the electron micrographs recorded from labeled and unlabeled structures.

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