Mycobacterium tuberculosis MycP1 Protease Plays a Dual Role in Regulation of ESX-1 Secretion and Virulence

SummaryMycobacterium tuberculosis uses the ESX-1 secretion system to deliver virulence proteins during infection of host cells. Here we report a mechanism of posttranscriptional control of ESX-1 mediated by MycP1, a M. tuberculosis serine protease. We show that MycP1 is required for ESX-1 secretion but that, unexpectedly, genetic inactivation of MycP1 protease activity increases secretion of ESX-1 substrates. We demonstrate that EspB, an ESX-1 substrate required for secretion, is a target of MycP1 in vitro and in vivo. During macrophage infection, an inactive MycP1 protease mutant causes hyperactivation of ESX-1-stimulated innate signaling pathways. MycP1 is required for growth in mice during acute infection, while loss of its protease activity leads to attenuated virulence during chronic infection. As the key ESX-1 substrates ESAT-6 and CFP-10 are highly immunogenic, fine-tuning of their secretion by MycP1 may balance virulence and immune detection and be essential for successful maintenance of long-term M. tuberculosis infection

Tuberculosis Toxin Blocking Phagosome Maturation Inhibits a Novel Ca2+/Calmodulin-PI3K hVPS34 Cascade

The capacity of Mycobacterium tuberculosis to infect latently over one billion people and cause two million fatalities annually rests with its ability to block phagosomal maturation into the phagolysosome in infected macrophages. Here we describe how M. tuberculosis toxin lipoarabinomannan (LAM) causes phagosome maturation arrest, interfering with a new pathway connecting intracellular signaling and membrane trafficking. LAM from virulent M. tuberculosis, but not from avirulent mycobacteria, blocked cytosolic Ca2+ increase. Ca2+ and calmodulin were required for a newly uncovered Ca2+/calmodulin phosphatidylinositol (PI)3 kinase hVPS34 cascade, essential for production of PI 3 phosphate (PI3P) on liposomes in vitro and on phagosomes in vivo. The interference of the trafficking toxin LAM with the calmodulin-dependent production of PI3P described here ensures long-term M. tuberculosis residence in vacuoles sequestered away from the bactericidal and antigen-processing organelles in infected macrophages

Strategic Scheduling of Infrastructure Repair and Maintenance: Volume 2—Developing Condition-Based Triggers for Bridge Maintenance and Rehabilitation Treatments

Even for the right treatment, improper timing can have consequences: premature application (treatment is applied too early) could mean wasteful spending even if users enjoy the benefits of higher pavement condition; deferred or delayed application (treatment is applied too late) could result in higher user costs due to poor condition and even reduced asset longevity. The objectives of this research were to establish the optimal condition or timing for each of the standard M&R treatment types typically used by INDOT; quantify the consequences of departures from such optimal conditions or timings; and to establish the optimal M&R treatment schedule for each asset family. The study focused on three asset types and their treatments: Painting of Steel Bridges. A painting decision tree was developed, to serve as a framework that would enable INDOT to consider other maintenance treatment types, namely spot repair/painting and overcoating. Bridge Deck Maintenance and Rehabilitation. Life-cycle condition-based deck M&R strategies based on different trigger results were proposed and presented. Pavement Maintenance, Rehabilitation, and Replacement. A framework was established to find the optimal scheduling for multiple treatments and recommend appropriate long-term M&R strategies for flexible and rigid pavements on different functional classes

Strategic Scheduling of Infrastructure Repair and Maintenance: Volume 1—Decision Tree for Steel Bridge Painting

Even for the right treatment, improper timing can have consequences: premature application (treatment is applied too early) could mean wasteful spending even if users enjoy the benefits of higher pavement condition; deferred or delayed application (treatment is applied too late) could result in higher user costs due to poor condition and even reduced asset longevity. The objectives of this research were to establish the optimal condition or timing for each of the standard M&R treatment types typically used by INDOT; quantify the consequences of departures from such optimal conditions or timings; and to establish the optimal M&R treatment schedule for each asset family. The study focused on three asset types and their treatments: Painting of Steel Bridges. A painting decision tree was developed, to serve as a framework that would enable INDOT to consider other maintenance treatment types, namely spot repair/painting and overcoating. Bridge Deck Maintenance and Rehabilitation. Life-cycle condition-based deck M&R strategies based on different trigger results were proposed and presented. Pavement Maintenance, Rehabilitation, and Replacement. A framework was established to find the optimal scheduling for multiple treatments and recommend appropriate long-term M&R strategies for flexible and rigid pavements on different functional classes

Strategic Scheduling of Infrastructure Repair and Maintenance: Volume 3—Developing Condition-Based Triggers for Pavement Maintenance, Rehabilitation, and Replacement Treatments

Even for the right treatment, improper timing can have consequences: premature application (treatment is applied too early) could mean wasteful spending even if users enjoy the benefits of higher pavement condition; deferred or delayed application (treatment is applied too late) could result in higher user costs due to poor condition and even reduced asset longevity. The objectives of this research were to establish the optimal condition or timing for each of the standard M&R treatment types typically used by INDOT; quantify the consequences of departures from such optimal conditions or timings; and to establish the optimal M&R treatment schedule for each asset family. The study focused on three asset types and their treatments: Painting of Steel Bridges. A painting decision tree was developed, to serve as a framework that would enable INDOT to consider other maintenance treatment types, namely spot repair/painting and overcoating. Bridge Deck Maintenance and Rehabilitation. Life-cycle condition-based deck M&R strategies based on different trigger results were proposed and presented. Pavement Maintenance, Rehabilitation, and Replacement. A framework was established to find the optimal scheduling for multiple treatments and recommend appropriate long-term M&R strategies for flexible and rigid pavements on different functional classes

Reactivation of M. tuberculosis Infection in Trans-Membrane Tumour Necrosis Factor Mice

Of those individuals who are infected with M. tuberculosis, 90% do not develop active disease and represents a large reservoir of M. tuberculosis with the potential for reactivation of infection. Sustained TNF expression is required for containment of persistent infection and TNF neutralization leads to tuberculosis reactivation. In this study, we investigated the contribution of soluble TNF (solTNF) and transmembrane TNF (Tm-TNF) in immune responses generated against reactivating tuberculosis. In a chemotherapy induced tuberculosis reactivation model, mice were challenged by aerosol inhalation infection with low dose M. tuberculosis for three weeks to establish infection followed chemotherapeutic treatment for six weeks, after which therapy was terminated and tuberculosis reactivation investigated. We demonstrate that complete absence of TNF results in host susceptibility to M. tuberculosis reactivation in the presence of established mycobacteria-specific adaptive immunity with mice displaying unrestricted bacilli growth and diffused granuloma structures compared to WT control mice. Interestingly, bacterial re-emergence is contained in Tm-TNF mice during the initial phases of tuberculosis reactivation, indicating that Tm-TNF sustains immune pressure as in WT mice. However, Tm-TNF mice show susceptibility to long term M. tuberculosis reactivation associated with uncontrolled influx of leukocytes in the lungs and reduced IL-12p70, IFNγ and IL-10, enlarged granuloma structures, and failure to contain mycobacterial replication relative to WT mice. In conclusion, we demonstrate that both solTNF and Tm-TNF are required for maintaining immune pressure to contain reactivating M. tuberculosis bacilli even after mycobacteria-specific immunity has been established

Short term X-ray rms variability of Cyg X-1

A linear dependence of the amplitude of broadband noise variability on flux for GBHC and AGN has been recently shown by Uttley & McHardy (2001). We present the long term evolution of this rms-flux-relation for Cyg X-1 as monitored from 1998-2002 with RXTE. We confirm the linear relationship in the hard state and analyze the evolution of the correlation for the period of 1996-2002. In the intermediate and the soft state, we find considerable deviations from the otherwise linear relationship. A possible explanation for the rms-flux-relation is a superposition of local mass accretion rate variations.Comment: 3 pages, 3 figures, Proceedings of the 4th Microquasar Workshop, eds. Ph Durouchoux, Y. Fuchs and J. Rodriguez, published by the Center for Space Physics: Kolkat

Rainbow Trout Spawning Characteristics and Relation to the Parasite Myxobolus cerebralis in the Missouri River, Montana

The myxosporean parasite Myxobolus cerebralis is responsible for significant declines of rainbow trout (Oncorhynchus mykiss) populations in several western states, including Montana. Despite a high prevalence of the parasite in Montana’s Missouri River, there have been no apparent impacts to the rainbow trout population. This study examined long-term M. cerebralis monitoring data from the Missouri River system below Holter Dam and evaluated rainbow trout spawning characteristics such as migration distance, spawning location, site fidelity and amount of spawning in the Missouri River and tributaries over three years in an attempt to explain why the population has not declined in the presence of M. cerebralis. Over 13 years of monitoring, a mean 5.3 percent of rainbow trout handled during population estimates had clinical signs of M. cerebralis infection. In experiments using sentinel fish 53 percent of the spawning habitat had high severity of M. cerebralis, 38 percent had low to moderate severity, and 9 percent had no infection. Radio telemetry showed spawning locations varied among years and tagged fish lacked spawning site fidelity. The distance that radio-tagged rainbow trout migrated to spawning locations was significantly different among river sections of the study area. Twenty-eight percent of the spawning redds were found in the Missouri River and 72 percent in the tributaries. Relative to previous studies, we found less tributary spawning and an increase in Missouri River spawning, where M. cerebralis infection severity is lower. Our findings suggest that diverse spawning behaviors may contribute to rainbow trout population stability by spreading the risk of M. cerebralis impact over spawning locations that have a broad range of infection severity

Arabinoxylans, inulin and Lactobacillus reuteri 1063 repress the adherent-invasive Escherichia coli from mucus in a musosa-comprising gut model

The microbiota that colonises the intestinal mucus may particularly affect human health given its proximity to the epithelium. For instance, the presence of the adherent-invasive Escherichia coli (AIEC) in this mucosal microbiota has been correlated with Crohn's disease. Using short-term screening assays and a novel long-term dynamic gut model, which comprises a simulated mucosal environment (M-SHIME), we investigated how (potential) pro-and prebiotics may repress colonisation of AIEC from mucus. Despite that during the short-term screening assays, some of the investigated Lactobacillus strains adhered strongly to mucins, none of them competed with AIEC for mucin-adhesion. In contrast, AIEC survival and growth during co-culture batch incubations was decreased by Lactobacillus rhamnosus GG and L. reuteri 1063, which correlated with (undissociated) lactic acid and reuterin levels. Regarding the prebiotics, long-chain arabinoxylans (LC-AX) lowered the initial mucin-adhesion of AIEC, while both inulin (IN) and galacto-oligosaccharides (GOS) limited AIEC survival and growth during batch incubations. L. reuteri 1063, LC-AX and IN were thus retained for a long-term study with the M-SHIME. All treatments repressed AIEC from mucus without affecting AIEC numbers in the luminal content. As a possible explanation, L. reuteri 1063 treatment increased lactobacilli levels in mucus, while LC-AX and IN additionally increased mucosal bifidobacteria levels, thus leading to antimicrobial effects against AIEC in mucus. Overall, this study shows that pro-and prebiotics can beneficially modulate the in vitro mucosal microbiota, thus limiting occurrence of opportunistic pathogens among those mucosal microbes which may directly interact with the host given their proximity to the epithelium