Type three secretion system-mediated escape of Burkholderia pseudomallei into the host cytosol is critical for the activation of NFκB.

BackgroundBurkholderia pseudomallei is the causative agent of melioidosis, a potentially fatal disease endemic in Southeast Asia and Northern Australia. This Gram-negative pathogen possesses numerous virulence factors including three "injection type" type three secretion systems (T3SSs). B. pseudomallei has been shown to activate NFκB in HEK293T cells in a Toll-like receptor and MyD88 independent manner that requires T3SS gene cluster 3 (T3SS3 or T3SSBsa). However, the mechanism of how T3SS3 contributes to NFκB activation is unknown.ResultsKnown T3SS3 effectors are not responsible for NFκB activation. Furthermore, T3SS3-null mutants are able to activate NFκB almost to the same extent as wildtype bacteria at late time points of infection, corresponding to delayed escape into the cytosol. NFκB activation also occurs when bacteria are delivered directly into the cytosol by photothermal nanoblade injection.ConclusionsT3SS3 does not directly activate NFκB but facilitates bacterial escape into the cytosol where the host is able to sense the presence of the pathogen through cytosolic sensors leading to NFκB activation

Flat-H Redundant Frangible Joint Design Evolution 2018: Feasibility Study Conclusions

This paper reports results of an investigation into developing a single failure tolerant pyrotechnic linear separation system which features completely redundant explosive trains suitable for human spaceflight. It is a follow up to Flat-H Redundant Frangible Joint Design Evolution 2017 and Flat-H Redundant Frangible Joint Evolution. The paper chronicles the history of the redundant frangible joint development program including testing, analysis, and design improvements from 2014 to the present culminating in a successful proof-of-concept prototype. The paper describes work done to address debris control and containment of combustion products. A performance optimization strategy is presented along with optimization results. Additionally a novel containment manifold design is presented with test results

Discovery and Early Evolution of ASASSN-19bt, the First TDE Detected by TESS

We present the discovery and early evolution of ASASSN-19bt, a tidal disruption event (TDE) discovered by the All-Sky Automated Survey for Supernovae (ASAS-SN) at a distance of $d\simeq115$ Mpc and the first TDE to be detected by TESS. As the TDE is located in the TESS Continuous Viewing Zone, our dataset includes 30-minute cadence observations starting on 2018 July 25, and we precisely measure that the TDE begins to brighten $\sim8.3$ days before its discovery. Our dataset also includes 18 epochs of Swift UVOT and XRT observations, 2 epochs of XMM-Newton observations, 13 spectroscopic observations, and ground data from the Las Cumbres Observatory telescope network, spanning from 32 days before peak through 37 days after peak. ASASSN-19bt thus has the most detailed pre-peak dataset for any TDE. The TESS light curve indicates that the transient began to brighten on 2019 January 21.6 and that for the first 15 days its rise was consistent with a flux $\propto t^2$ power-law model. The optical/UV emission is well-fit by a blackbody SED, and ASASSN-19bt exhibits an early spike in its luminosity and temperature roughly 32 rest-frame days before peak and spanning up to 14 days that has not been seen in other TDEs, possibly because UV observations were not triggered early enough to detect it. It peaked on 2019 March 04.9 at a luminosity of $L\simeq1.3\times10^{44}$ ergs s$^{-1}$ and radiated $E\simeq3.2\times10^{50}$ ergs during the 41-day rise to peak. X-ray observations after peak indicate a softening of the hard X-ray emission prior to peak, reminiscent of the hard/soft states in X-ray binaries.Comment: 23 pages, 14 figures, 5 tables. A machine-readable table containing the host-subtracted photometry presented in this manuscript is included as an ancillary fil

Rapid weight gain and weight differential predict competitive success in 2100 professional combat-sport athletes.

Purpose: Combat-sport athletes commonly undergo rapid weight loss prior to prebout weigh-in and subsequently rapid weight gain (RWG) prior to competition. This investigation aimed to evaluate the effect of RWG and weight differential (WD) between opponents on competitive success. Methods: A retrospective cohort study was performed using data from professional mixed martial arts (MMA) and boxing events held between 2015 and 2019. The primary outcome was RWG (relative and absolute) between weigh-in and competition stratified by bout winners and losers. Binary logistic regression was used to explore the relationships among bout outcome, RWG, and WD between competitors on the day of their bout. Results: Among 708 MMA athletes included, winners regained more relative body mass (8.7% [3.7%] vs 7.9% [3.8%], P < .01) than losers. In 1392 included male boxers, winners regained significantly more relative body mass (8.0% [3.0%] vs 6.9% [3.2%], P < .01) than losers. Each percentage body mass increase resulted in a 7% increased likelihood of victory in MMA and a 13% increase in boxing. The relationship between RWG and competitive success remained significant in regional and male international MMA athletes, as well as boxers. WD predicted victory in international mixed martial artists and boxers. WD predicted victory by knockout or technical knockout in international MMA athletes and regional boxers. Conclusion: This analysis of combat-sport athletes indicates that RWG and WD influence competitive success. These findings raise fair-play and safety concerns in these popular sports and may help guide risk-mitigating regulation strategies

Diel surface temperature range scales with lake size

Ecological and biogeochemical processes in lakes are strongly dependent upon water temperature. Long-term surface warming of many lakes is unequivocal, but little is known about the comparative magnitude of temperature variation at diel timescales, due to a lack of appropriately resolved data. Here we quantify the pattern and magnitude of diel temperature variability of surface waters using high-frequency data from 100 lakes. We show that the near-surface diel temperature range can be substantial in summer relative to long-term change and, for lakes smaller than 3 km2, increases sharply and predictably with decreasing lake area. Most small lakes included in this study experience average summer diel ranges in their near-surface temperatures of between 4 and 7°C. Large diel temperature fluctuations in the majority of lakes undoubtedly influence their structure, function and role in biogeochemical cycles, but the full implications remain largely unexplored

Understanding the circumgalactic medium is critical for understanding galaxy evolution

Galaxies evolve under the influence of gas flows between their interstellar medium and their surrounding gaseous halos known as the circumgalactic medium (CGM). The CGM is a major reservoir of galactic baryons and metals, and plays a key role in the long cycles of accretion, feedback, and recycling of gas that drive star formation. In order to fully understand the physical processes at work within galaxies, it is therefore essential to have a firm understanding of the composition, structure, kinematics, thermodynamics, and evolution of the CGM. In this white paper we outline connections between the CGM and galactic star formation histories, internal kinematics, chemical evolution, quenching, satellite evolution, dark matter halo occupation, and the reionization of the larger-scale intergalactic medium in light of the advances that will be made on these topics in the 2020s. We argue that, in the next decade, fundamental progress on all of these major issues depends critically on improved empirical characterization and theoretical understanding of the CGM. In particular, we discuss how future advances in spatially-resolved CGM observations at high spectral resolution, broader characterization of the CGM across galaxy mass and redshift, and expected breakthroughs in cosmological hydrodynamic simulations will help resolve these major problems in galaxy evolution.Comment: Astro2020 Decadal Science White Pape

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Protein secretion systems in Bordetella and Burkholderia species and their roles in virulence

Bordetella and Burkholderia species are significant human and animal pathogens. Bordetella pertussis, B. parapertussis and B. bronchiseptica colonize respiratory epithelium to cause human pertussis and pertussis-like respiratory illnesses, while Burkholderia pseudomallei and its less-virulent relative Burkholderia thailandensis are soil organisms that can behave as opportunistic pathogens and survive as facultative intracellular parasites. Bordetella and Burkholderia are well equipped with virulence determinants, including multiple protein secretion systems. In the first section of this dissertation I describe an analysis of the Bordetella type III secretion (T3SS) effector protein BteA, which is necessary and sufficient for the induction of rapid toxicity in a variety of mammalian cell lines. We identify a N-terminal domain of BteA that mediates its localization to lipid raft domains of mammalian cells following ectopic expression and T3SS-mediated translocation by B. bronchiseptica. The rest of the dissertation is focused on the secretion systems and virulence mechanisms in B. pseudomallei and B. thailandensis. Unlike Bordetella, which contains a single injection-type T3SS and one known effector protein BteA, Burkholderia pseudomallei contains three injection T3SSs that function in mediating its interactions with other organisms in the rhizosphere and in mammalian pathogenesis. In the second section of the dissertation, the roles of T3SS and other virulence mechanisms are closely examined in the intracellular lifecycle of Burkholderia. Bacteria were delivered directly into the cytoplasm of mammalian cells using a photothermal nanoblade device, bypassing invasion and the need to escape from endosomes. Activity of the Burkholderia secretion apparatus T3SS (T3SSBsa) was critical for endosome escape following infection, but was not required for subsequent actin polymerization, intercellular spread and the fusion of host cell membranes to form multinucleate giant cells (MNGCs) following cytosolic nanoblade delivery of bacteria. Motility, mediated by either the Fla2 flagellar system or actin polymerization, was required for cell-cell spread and MNGC formation by B. thailandensis and B. pseudomallei, as was the activity of a type VI secretion (T6SS) system. We conclude that the primary means for intercellular spread involves cell fusion, as opposed to pseudopod engulfment and bacterial escape from double-membrane vacuoles. The third section of the dissertation describes further analysis of the Fla2 flagellar T3SS and B. pseudomallei injection T3SS effector proteins. Using confocal immunofluorescence microscopy, we discovered that fla2 encodes multiple, lateral flagellar filaments and is activated following infection of mammalian cells. Surprisingly, constitutive expression of a Fla2 response regulator protein, Frr, strongly reduced plaquing efficiency in B. pseudomallei and B. thailandensis. I also describe the identification and analysis of novel B. pseudomallei effector protein (Bep) candidates. Specific phenotypes for six Bep proteins were observed following transfections of HeLa cells; BepA exhibited perinuclear localization, BepB resulted in cytotoxicity and alterations in cell morphology, BepC bundled actin, BepD decorated microtubules, and BepE and BepF rearranged actin and altered cell morphology. However, strains carrying deletion mutations in single Bep effector candidate loci did not exhibit defects following infection of mammalian cells. A single strain containing deletions in BopA, BopC and BopE, the three previously known T3SSBsa effectors, exhibited reduced plaque formation in RAW264.7 macrophages. Of the three effectors, only BopA was seen to play a major role in B. pseudomallei intracellular pathogenesis

Environmental influences on fish assemblage in the Venice Lagoon, Italy

This study aimed to investigate the small fish assemblage in the Venice Lagoon shallow waters in relation to selected environmental variables, such as water-quality parameters, sediment grain-size variables, and habitat structure factors. Fish sampling was carried out in 68 stations, seasonally, by using a small beach seine net. The results highlighted the primary importance of habitat structure variables, such as seagrass and salt marsh coverages, with regard to fish distribution in the lagoon, in association with turbidity and salinity gradients. Two distinct fish assemblages were identified, corresponding to opposite species preferences in relation to salt marsh coverage-turbidity and seagrass coverage-salinity gradients. These results confirmed the importance of the biologically mediated influence of environmental parameters over physical parameters on small fish assemblages in dynamic systems such as the Venice Lagoon