- Transcriptomic Analysis of Trichoderma atroviride Overgrowing Plant-Wilting Verticillium dahliae Reveals the Role of a New M14 Metallocarboxypeptidase CPA1 in Biocontrol. [Journal Article]
- FMFront Microbiol 2019; 10:1120
- Verticillium dahliae, a vascular-colonizing fungus, causes economically important wilt diseases in many crops, including olive trees. Trichoderma spp. have demonstrated an effective contribution as b…
Verticillium dahliae, a vascular-colonizing fungus, causes economically important wilt diseases in many crops, including olive trees. Trichoderma spp. have demonstrated an effective contribution as biocontrol agents against this pathogen through a variety of mechanisms that may involve direct mycoparasitism and antibiosis. However, molecular aspects underlaying Trichoderma-V. dahliae interactions are not well known yet due to the few studies in which this pathogen has been used as a target for Trichoderma. In the present study, Trichoderma atroviride T11 overgrew colonies of V. dahliae on agar plates and inhibited growth of highly virulent defoliating (D) V. dahliae V-138I through diffusible molecules and volatile organic compounds produced before contact. A Trichoderma microarray approach of T11 growing alone (CON), and before contact (NV) or overgrowing (OV) colonies of V-138I, helped to identify 143 genes that differed significantly in their expression level by more than twofold between OV and CON or NV. Functional annotation of these genes indicated a marked up-regulation of hydrolytic, catalytic and transporter activities, and secondary metabolic processes when T11 overgrew V-138I. This transcriptomic analysis identified peptidases as enzymatic activity overrepresented in the OV condition, and the cpa1 gene encoding a putative carboxypeptidase (ID number 301733) was selected to validate this study. The role of cpa1 in strain T11 on antagonism of V-138I was analyzed by a cpa1-overexpression approach. The increased levels of cpa1 expression and protease activity in the cpa1-overexpressed transformants compared to those in wild-type or transformation control strains were followed by significantly higher antifungal activity against V-138I in in vitro assays. The use of Trichoderma spp. for the integrated management of plant diseases caused by V. dahliae requires a better understanding of the molecular mechanisms underlying this interaction that might provide an increase on its efficiency.
- 3D Digitization in Functional Morphology: Where is the Point of Diminishing Returns? [Journal Article]
- ICIntegr Comp Biol 2019 Jun 11
- Modern computational and imaging methods are revolutionizing the fields of comparative morphology, biomechanics, and ecomorphology. In particular, imaging tools such as micro-X-ray Computed Tomograph…
Modern computational and imaging methods are revolutionizing the fields of comparative morphology, biomechanics, and ecomorphology. In particular, imaging tools such as micro-X-ray Computed Tomography (µCT) and diffusible iodine-based contrast enhanced CT (diceCT) allow observing and measuring small and/or otherwise inaccessible anatomical structures, and creating highly accurate 3D renditions that can be used in biomechanical modeling and tests of functional or evolutionary hypotheses. But, do the larger datasets generated through 3D digitization always confer greater power to uncover functional or evolutionary patterns, when compared with more traditional methodologies? And, if so, why? Here, we contrast the advantages and challenges of using data generated via (3D) CT methods versus more traditional (2D) approaches in the study of skull macroevolution and feeding functional morphology in bats. First, we test for the effect of dimensionality and landmark number on inferences of adaptive shifts during cranial evolution by contrasting results from 3D versus 2D geometric morphometric datasets of bat crania. We find sharp differences between results generated from the 3D versus some of the 2D datasets (xy, yz, ventral, frontal), which appear to be primarily driven by the loss of critical dimensions of morphological variation rather than number of landmarks. Second, we examine differences in accuracy and precision among 2D and 3D predictive models of bite force by comparing three skull lever models that differ in the sources of skull and muscle anatomical data. We find that a 3D model that relies on skull µCT scans and muscle data party derived from diceCT is slightly more accurate than models based on skull photographs or skull µCT, and muscle data fully derived from dissections. However, the benefit of using the diceCT-informed model is modest given the effort it currently takes to virtually dissect muscles from CT scans. By contrasting traditional and modern tools, we illustrate when and why 3D datasets may be preferable over 2D data, and vice versa, and how different methodologies can complement each other in comparative analyses of morphological function and evolution.
- Maturation of retroviruses. [Review]
- COCurr Opin Virol 2019 Jun 07; 36:47-55
- During retrovirus maturation, cleavage of the precursor structural Gag polyprotein by the viral protease induces architectural rearrangement of the virus particle from an immature into a mature, infe…
During retrovirus maturation, cleavage of the precursor structural Gag polyprotein by the viral protease induces architectural rearrangement of the virus particle from an immature into a mature, infectious form. The structural rearrangement encapsidates the viral RNA genome in a fullerene capsid, producing a diffusible viral core that can initiate infection upon entry into the cytoplasm of a host cell. Maturation is an important therapeutic window against HIV-1. In this review, we highlight recent breakthroughs in understanding of the structures of retroviral immature and mature capsid lattices that define the boundary conditions of maturation and provide novel insights on capsid transformation. We also discuss emerging insights on encapsidation of the viral genome in the mature capsid, as well as remaining questions for further study.
- Lymphatic Vessel Pumping. [Journal Article]
- AEAdv Exp Med Biol 2019; 1124:357-377
- The lymphatic system extends its network of vessels throughout most of the body. Lymphatic vessels carry a fluid rich in proteins, immune cells, and long-chain fatty acids known as lymph. It results …
The lymphatic system extends its network of vessels throughout most of the body. Lymphatic vessels carry a fluid rich in proteins, immune cells, and long-chain fatty acids known as lymph. It results from an excess of interstitial tissue fluid collected from the periphery and transported centrally against hydrostatic pressure and protein concentration gradients. Thus, this one-way transport system is a key component in the maintenance of normal interstitial tissue fluid volume, protein concentration and fat metabolism, as well as the mounting of adequate immune responses as lymph passes through lymph nodes. In most cases, lymph is actively propelled via rhythmical phasic contractions through a succession of valve-bordered chambers constituting the lymphatic vessels. This contraction/relaxation cycle, or lymphatic pumping, is initiated in the smooth muscle cells present in the vessel wall by a pacemaker mechanism generating voltage-gated Ca2+ channel-induced action potentials. The action potentials provide the depolarization and Ca2+ influx essential for the engagement of the contractile machinery leading to the phasic constrictions of the lymphatic chambers and forward movement of lymph. The spontaneous lymphatic constrictions can be observed in isolated vessels in the absence of any external stimulation, while they are critically regulated by physical means, such as lymph-induced transmural pressure and flow rate, as well as diffusible molecules released from the lymphatic endothelium, perivascular nerve varicosities, blood and surrounding tissues/cells. In this chapter, we describe the latest findings which are improving our understanding of the mechanisms underlying spontaneous lymphatic pumping and discuss current theories about their physiological initiation.
- Predicting Phosphate Release from Sewage Sludge Ash Using an Ion Sink Assay. [Journal Article]
- JEJ Environ Qual 2019; 48(3):746-754
- Thermochemical treatments allow production of sewage sludge ash (SSA) rich in P and low in heavy metals, which could be recycled in agriculture. Our objective was to quantify P release from SSA using…
Thermochemical treatments allow production of sewage sludge ash (SSA) rich in P and low in heavy metals, which could be recycled in agriculture. Our objective was to quantify P release from SSA using ion sink assays and to relate these results to P speciation in SSA and plant P uptake. Anion and cation exchange membranes saturated with different counterions (HCO, Na, and H) were used to create a gradient in pH, P, or cation concentration between SSA particles and the surrounding solution. Phosphorus speciation in SSA was assessed using X-ray powder diffraction, and plant P uptake was determined in a pot experiment with an acidic and a neutral soil. Four SSA products were investigated: a SSA thermochemically treated with CaCl or MgCl (SSA Ca/Mg), a SSA blended with KCl, and a SSA blended with KCl and triple superphosphate (TSP) to obtain a marketable 12-20 P-K fertilizer. The H membranes dissolved all P species present in SSA. Combined HCO/Na membranes extracted diffusible P and noncrystalline P from SSA Ca/Mg and stanfieldite from SSA Mg. Blending with KCl hardly changed P release from SSA, whereas blending with TSP masked P release. The amount of P extracted from SSA by combined HCO/Na membranes was correlated to plant P use in the acid soil, whereas the amount of P extracted by HCO membranes alone was correlated to P use in the neutral soil. In conclusion, the ion sink assays delivered information on P release that was related to both SSA mineralogy and P use by plants.
- Organization of Embryonic Morphogenesis via Mechanical Information. [Journal Article]
- DCDev Cell 2019 May 28
- Embryonic organizers establish gradients of diffusible signaling molecules to pattern the surrounding cells. Here, we elucidate an additional mechanism of embryonic organizers that is a secondary con…
Embryonic organizers establish gradients of diffusible signaling molecules to pattern the surrounding cells. Here, we elucidate an additional mechanism of embryonic organizers that is a secondary consequence of morphogen signaling. Using pharmacological and localized transgenic perturbations, 4D imaging of the zebrafish embryo, systematic analysis of cell motion, and computational modeling, we find that the vertebrate tail organizer orchestrates morphogenesis over distances beyond the range of morphogen signaling. The organizer regulates the rate and coherence of cell motion in the elongating embryo using mechanical information that is transmitted via relay between neighboring cells. This mechanism is similar to a pressure front in granular media and other jammed systems, but in the embryo the mechanical information emerges from self-propelled cell movement and not force transfer between cells. The propagation likely relies upon local biochemical signaling that affects cell contractility, cell adhesion, and/or cell polarity but is independent of transcription and translation.
- Colletotrichum acutatum M11 can suppress the defence response in strawberry plants. [Journal Article]
- PPlanta 2019 Jun 06
- CONCLUSIONS: Colletotrichum acutatum M11 produces a diffusible compound that suppresses the biochemical, physiological, molecular and anatomical events associated with the defence response induced by the plant defence elicitor AsES. The fungal pathogen Colletotrichum acutatum, the causal agent of anthracnose disease, causes important economical losses in strawberry crop worldwide and synthetic agrochemicals are used to control it. In this context, the control of the disease using bioproducts is gaining reputation as an alternative of those toxic and pollutant agrochemicals. However, the success of the strategies using bioproducts can be seriously jeopardized in the presence of biological agents exerting a defence suppression effect. In this report, we show that the response defence induced in plant by the elicitor AsES from the fungus Acremonium strictum can be suppressed by a diffusible compound produced by isolate M11 of C. acutatum. Results revealed that strawberry plants treated with conidia of the isolated M11 or the culture supernatant of the isolate M11 suppress: ROS accumulation (e.g., H2O2, O2·- and NO), cell wall reinforcement (e.g., lignin and callose), and the up-regulation of defence-related genes (e.g., FaPR1, FaCHI23, FaPDF1.2, FaCAT, FaCDPK, FaCML39) induced by the elicitor AsES. Additionally, we show that the defence suppressing effect causes a systemic sensitization of plants. Results presented here highlights the necessity to make an integral study of the microbiome present in soils and plant biosphere before applying defence activation bioproducts to control crop diseases.
- Lipid-dependent Akt-ivity: where, when, and how. [Review]
- BSBiochem Soc Trans 2019 May 30
- Akt is an essential protein kinase activated downstream of phosphoinositide 3-kinase and frequently hyperactivated in cancer. Canonically, Akt is activated by phosphoinositide-dependent kinase 1 and …
Akt is an essential protein kinase activated downstream of phosphoinositide 3-kinase and frequently hyperactivated in cancer. Canonically, Akt is activated by phosphoinositide-dependent kinase 1 and mechanistic target of rapamycin complex 2, which phosphorylate it on two regulatory residues in its kinase domain upon targeting of Akt to the plasma membrane by PI(3,4,5)P3 Recent evidence, however, has shown that, in addition to phosphorylation, Akt activity is allosterically coupled to the engagement of PI(3,4,5)P3 or PI(3,4)P2 in cellular membranes. Furthermore, the active membrane-bound conformation of Akt is protected from dephosphorylation, and Akt inactivation by phosphatases is rate-limited by its dissociation. Thus, Akt activity is restricted to membranes containing either PI(3,4,5)P3 or PI(3,4)P2 While PI(3,4,5)P3 has long been associated with signaling at the plasma membrane, PI(3,4)P2 is gaining increasing traction as a signaling lipid and has been implicated in controlling Akt activity throughout the endomembrane system. This has clear implications for the phosphorylation of both freely diffusible substrates and those localized to discrete subcellular compartments.
- Evidence for distinct rate-limiting steps in the cleavage of alkenes by carotenoid cleavage dioxygenases. [Journal Article]
- JBJ Biol Chem 2019 May 28
- Carotenoid cleavage dioxygenases (CCDs) use a non-heme Fe(II) cofactor to split alkene bonds of carotenoid and stilbenoid substrates. The iron centers of CCDs are typically five-coordinate in their r…
Carotenoid cleavage dioxygenases (CCDs) use a non-heme Fe(II) cofactor to split alkene bonds of carotenoid and stilbenoid substrates. The iron centers of CCDs are typically five-coordinate in their resting states, with solvent occupying an exchangeable site. The involvement of this iron-bound solvent in CCD catalysis has not been experimentally addressed, but computational studies suggest two possible roles: 1) solvent dissociation provides a coordination site for O2, or 2) solvent remains bound to iron but changes its equilibrium position to allow O2 binding and potentially acts as a proton source. To test these predictions, we investigated isotope effects (H2O versus D2O) on two stilbenoid-cleaving CCDs, Novosphingobium aromaticivorans oxygenase 2 (NOV2) and Neurospora crassa carotenoid oxygenase 1 (CAO1), using piceatannol as a substrate. NOV2 exhibited an inverse isotope effect (kH/kD ~0.6) in an air-saturated buffer, suggesting that solvent dissociates from iron during the catalytic cycle. By contrast, CAO1 displayed a normal isotope effect (kH/kD ~1.7) suggesting proton transfer in the rate-limiting step. X-ray absorption spectroscopy on NOV2 and CAO1 indicated that the protonation states of the iron ligands are unchanged within the pH 6.5-8.5 and that the Fe(II)-aquo bond is minimally altered by substrate binding. We pinpointed the origin of the differential kinetic behaviors of NOV2 and CAO1 to a single amino acid difference near the solvent-binding site of iron, and X-ray crystallography revealed that the substitution alters binding of diffusible ligand to the iron center. We conclude that solvent-iron dissociation and proton transfer are both associated with the CCD catalytic mechanism.
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- Modulation of antibiotic sensitivity and biofilm formation in Pseudomonas aeruginosa by interspecies signal analogues. [Journal Article]
- NCNat Commun 2019 05 27; 10(1):2334
- Pseudomonas aeruginosa, a significant opportunistic pathogen, can participate in inter-species communication through signaling by cis-2-unsaturated fatty acids of the diffusible signal factor (DSF) f…
Pseudomonas aeruginosa, a significant opportunistic pathogen, can participate in inter-species communication through signaling by cis-2-unsaturated fatty acids of the diffusible signal factor (DSF) family. Sensing these signals leads to altered biofilm formation and increased tolerance to various antibiotics, and requires the histidine kinase PA1396. Here, we show that the membrane-associated sensory input domain of PA1396 has five transmembrane helices, two of which are required for DSF sensing. DSF binding is associated with enhanced auto-phosphorylation of PA1396 incorporated into liposomes. Further, we examined the ability of synthetic DSF analogues to modulate or inhibit PA1396 activity. Several of these analogues block the ability of DSF to trigger auto-phosphorylation and gene expression, whereas others act as inverse agonists reducing biofilm formation and antibiotic tolerance, both in vitro and in murine infection models. These analogues may thus represent lead compounds to develop novel adjuvants improving the efficacy of existing antibiotics.