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Find video protocols related to scientific articles indexed in Pubmed.
MG428 is a novel positive regulator of recombination that triggers mgpB and mgpC gene variation in Mycoplasma genitalium.
Mol. Microbiol.
PUBLISHED: 09-05-2014
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The human pathogen Mycoplasma genitalium employs homologous recombination to generate antigenic diversity in the immunodominant MgpB and MgpC proteins. Only recently, some of the molecular factors involved in this process have been characterized, but nothing is known about its regulation. Here, we show that M. genitalium expresses N-terminally truncated RecA isoforms via alternative translation initiation, but only the full-length protein is essential for gene variation. We also demonstrate that overexpression of MG428 positively regulates the expression of recombination genes, including recA, ruvA, ruvB and ORF2, a gene of unknown function co-transcribed with ruvAB. The co-ordinated induction of these genes correlated with an increase of mgpBC gene variation. In contrast, cells lacking MG428 were unable to generate variants despite expressing normal levels of RecA. Similarly, deletion analyses of the recA upstream region defined sequences required for gene variation without abolishing RecA expression. The requirement of these sequences is consistent with the presence of promoter elements associated with MG428-dependent recA induction. Sequences upstream of recA also influence the relative abundance of RecA isoforms, possibly through translational regulation. Overall, these results suggest that MG428 is a positive regulator of recombination and that precise control of recA expression is required to initiate mgpBC variation.
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Characterization of the operon encoding the Holliday junction helicase RuvAB from Mycoplasma genitalium and its role in mgpB and mgpC gene variation.
J. Bacteriol.
PUBLISHED: 02-14-2014
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Mycoplasma genitalium is an emerging sexually transmitted pathogen associated with reproductive tract disease in men and women, and it can persist for months to years despite the development of a robust antibody response. Mechanisms that may contribute to persistence in vivo include phase and antigenic variation of the MgpB and MgpC adhesins. These processes occur by segmental recombination between discrete variable regions within mgpB and mgpC and multiple archived donor sequences termed MgPa repeats (MgPars). The molecular factors governing mgpB and mgpC variation are poorly understood and obscured by the paucity of recombination genes conserved in the M. genitalium genome. Recently, we demonstrated the requirement for RecA using a quantitative PCR (qPCR) assay developed to measure recombination between the mgpB and mgpC genes and MgPars. Here, we expand these studies by examining the roles of M. genitalium ruvA and ruvB homologs. Deletion of ruvA and ruvB impaired the ability to generate mgpB and mgpC phase and sequence variants, and these deficiencies could be complemented with wild-type copies, including the ruvA gene from Mycoplasma pneumoniae. In contrast, ruvA and ruvB deletions did not affect the sensitivity to UV irradiation, reinforcing our previous findings that the recombinational repair pathway plays a minor role in M. genitalium. Reverse transcription-PCR (RT-PCR) and primer extension analyses also revealed a complex transcriptional organization of the RuvAB system of M. genitalium, which is cotranscribed with two novel open reading frames (ORFs) (termed ORF1 and ORF2 herein) conserved only in M. pneumoniae. These findings suggest that these novel ORFs may play a role in recombination in these two closely related bacteria.
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RADIAL: a novel primary graft failure risk score in heart transplantation.
J. Heart Lung Transplant.
PUBLISHED: 01-28-2011
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Primary graft failure (PGF) is the leading cause of early mortality after heart transplantation (HT). Our aim is to propose a working definition of PGF and to develop a predictive risk score.
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Factors influencing the mechanical behaviour of healthy human descending thoracic aorta.
Physiol Meas
PUBLISHED: 10-27-2010
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In recent times, significant effort has been made to understand the mechanical behaviour of the arterial wall and how it is affected by the different vascular pathologies. However, to be able to interpret the results correctly, it is essential that the influence of other factors, such as aging or anisotropy, be understood. Knowledge of mechanical behaviour of the aorta has been customarily constrained by lack of data on fresh aortic tissue, especially from healthy young individuals. In addition, information regarding the point of rupture is also very limited. In this study, the mechanical behaviour of the descending thoracic aorta of 28 organ donors with no apparent disease, whose ages vary from 17 to 60 years, is evaluated. Tensile tests up to rupture are carried out to evaluate the influence of age and wall anisotropy. Results reveal that the tensile strength and stretch at failure of healthy descending aortas show a significant reduction with age, falling abruptly beyond the age of 30. This fact places age as a key factor when mechanical properties of descending aorta are considered.
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Intravascular ultrasound measurement of the aortic lumen.
Rev Esp Cardiol
PUBLISHED: 05-11-2010
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Intravascular ultrasound (IVUS) has been successfully used to guide the implantation of stents in the thoracic aorta. However, its accuracy in measuring the diameter of the aortic lumen has not been clearly established. Thirteen patients with thoracic aortic disease underwent IVUS, and lumen diameter measurements were compared with those obtained by CT or magnetic resonance imaging. A total of 31 comparable measurements were obtained. The correlation was good (r=0.98; P< .001), with IVUS tending to give a larger minimum diameter than CT (systematic error, 0.59+/-1.8 mm; P=.077). Given that the aorta is often not circular, the diameter obtained by IVUS was also compared to the mean diameter obtained by CT, and it was found that these two measurements were more closely related (P=.425), except in aortic segments with significant eccentricity (i.e., >10%). In conclusion, IVUS was a reliable tool for measuring the diameter of the aorta, particularly in concentric segments where stents are normally placed. Consequently, IVUS could supplement conventional imaging techniques.
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P110 and P140 cytadherence-related proteins are negative effectors of terminal organelle duplication in Mycoplasma genitalium.
PLoS ONE
PUBLISHED: 08-10-2009
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The terminal organelle is a complex structure involved in many aspects of the biology of mycoplasmas such as cell adherence, motility or cell division. Mycoplasma genitalium cells display a single terminal organelle and duplicate this structure prior to cytokinesis in a coordinated manner with the cell division process. Despite the significance of the terminal organelle in mycoplasma virulence, little is known about the mechanisms governing its duplication.
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RecA mediates MgpB and MgpC phase and antigenic variation in Mycoplasma genitalium, but plays a minor role in DNA repair.
Mol. Microbiol.
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Mycoplasma genitalium, a sexually transmitted human pathogen, encodes MgpB and MgpC adhesins that undergo phase and antigenic variation through recombination with archived MgPar donor sequences. The mechanism and molecular factors required for this genetic variation are poorly understood. In this study, we estimate that sequence variation at the mgpB/C locus occurs in vitro at a frequency of > 1.25 × 10(-4) events per genome per generation using a quantitative anchored PCR assay. This rate was dramatically reduced in a recA deletion mutant and increased in a complemented strain overexpressing RecA. Similarly, the frequency of haemadsorption-deficient phase variants was reduced in the recA mutant, but restored by complementation. Unlike Escherichia coli, inactivation of recA in M. genitalium had a minimal effect on survival after exposure to mitomycin C or UV irradiation. In contrast, a deletion mutant for the predicted nucleotide excision repair uvrC gene showed growth defects and was exquisitely sensitive to DNA damage. We conclude that M. genitalium RecA has a primary role in mgpB/C-MgPar recombination leading to antigenic and phase variation, yet plays a minor role in DNA repair. Our results also suggest that M. genitalium possesses an active nucleotide excision repair system, possibly representing the main DNA repair pathway in this minimal bacterium.
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What is Visualize?

JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

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We use abstracts found on PubMed and match them to JoVE videos to create a list of 10 to 30 related methods videos.

Video X seems to be unrelated to Abstract Y...

In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.