326 research outputs found

    Differential responses of Duo grass (Lolium Ă— Festuca), a phosphorus hyperaccumulator to high phosphorus and poultry manure treatments

    Get PDF
    Use of suitable plants to extract and concentrate excess phosphorus (P) from contaminated soil serves as an attractive method of phyto-remediation. Plant species vary considerably in their potential to assimilate different organic and inorganic P substrates. Duo grass (a hybrid of Lolium Ă— Festuca) seedlings were grown in liquid nutrient media supplemented with various concentrations of potassium dihydrogen phosphate (KH2PO4) and phytate to study their P-accumulation potential. Plants that received extra P showed significantly greater plant biomass and accumulated more shoot P compared to the plants that were supplied with normal P. Duo was also grown in poultry manure amended soil and liquid media to evaluate their ability to grow and accumulate biomass in poultry manure impacted soils. Thus this grass species may be utilized as a P hyper-accumulator for phyto-extraction of excess P into their biomass from soils. Duo grass can utilize both organic (phytate), as well as, inorganic P from the growth medium as evidenced in the results.Keywords: Duo grass, phosphorus, phosphorus substrates, phytate, phosphorus accumulation, phytoremediationAfrican Journal of Biotechnology Vol. 12(21), pp. 3191-319

    Contemporary Use of Balloon Aortic Valvuloplasty in the Era of Transcatheter Aortic Valve Implantation

    Get PDF
    The development of transcatheter aortic valve implantation (TAVI) has increased the use of balloon aortic valvuloplasty (BAV) in treating aortic stenosis. We evaluated our use of BAV in an academic tertiary referral center with a developing TAVI program. We reviewed 69 consecutive stand-alone BAV procedures that were performed in 62 patients (mean age, 77 ± 10 yr; 62% men; baseline mean New York Heart Association functional class, 3 ± 1) from January 2009 through December 2012. Enrollment for the CoreValve® clinical trial began in January 2011. We divided the study cohort into 2 distinct periods, defined as pre-TAVI (2009–2010) and TAVI (2011–2012). We reviewed clinical, hemodynamic, and follow-up data, calculating each BAV procedure as a separate case. Stand-alone BAV use increased 145% from the pre-TAVI period to the TAVI period. The mean aortic gradient reduction was 13 ± 10 mmHg. Patients were successfully bridged as intended to cardiac or noncardiac surgery in 100% of instances and to TAVI in 60%. Five patients stabilized with BAV subsequently underwent surgical aortic valve replacement with no operative deaths. The overall in-hospital mortality rate (17.4%) was highest in emergent patients (61%). The implementation of a TAVI program was associated with a significant change in BAV volumes and indications. Balloon aortic valvuloplasty can successfully bridge patients to surgery or TAVI, although least successfully in patients nearer death. As TAVI expands to more centers and higher-risk patient groups, BAV might become integral to collaborative treatment decisions by surgeons and interventional cardiologists

    The role of charge in the toxicity of polymer-coated cerium oxide nanomaterials to Caenorhabditis elegans

    Get PDF
    This study examined the impact of surface functionalization and charge on ceria nanomaterial toxicity to Caenorhabditis elegans. The examined endpoints included mortality, reproduction, protein expression, and protein oxidation profiles. Caenorhabditis elegans were exposed to identical 2–5 nm ceria nanomaterial cores which were coated with cationic (diethylaminoethyl dextran; DEAE), anionic (carboxymethyl dextran; CM), and non-ionic (dextran; DEX) polymers. Mortality and reproductive toxicity of DEAE-CeO2 was approximately two orders of magnitude higher than for CM-CeO2 or DEX-CeO2. Two-dimensional gel electrophoresis with orbitrap mass spectrometry identification revealed changes in the expression profiles of several mitochondrial-related proteins and proteins that are expressed in the C. elegans intestine. However, each type of CeO2 material exhibited a distinct protein expression profile. Increases in protein carbonyls and protein-bound 3-nitrotyrosine were also observed for some proteins, indicating oxidative and nitrosative damage. Taken together the results indicate that the magnitude of toxicity and toxicity pathways vary greatly due to surface functionalization of CeO2 nanomaterials

    Viral genome packaging terminase cleaves DNA using the canonical RuvC-like two-metal catalysis mechanism

    Get PDF
    Bacteriophages and large dsDNA viruses encode sophisticated machinery to translocate their DNA into a preformed empty capsid. An essential part of this machine, the large terminase protein, processes viral DNA into constituent units utilizing its nuclease activity. Crystal structures of the large terminase nuclease from the thermophilic bacteriophage G20c show that it is most similar to the RuvC family of the RNase H-like endonucleases. Like RuvC proteins, the nuclease requires either Mn2+, Mg2+ or Co2+ ions for activity, but is inactive with Zn2+ and Ca2+. High resolution crystal structures of complexes with different metals reveal that in the absence of DNA, only one catalytic metal ion is accommodated in the active site. Binding of the second metal ion may be facilitated by conformational variability, which enables the two catalytic aspartic acids to be brought closer to each other. Structural comparison indicates that in common with the RuvC family, the location of the two catalytic metals differs from other members of the RNase H family. In contrast to a recently proposed mechanism, the available data do not support binding of the two metals at an ultra-short interatomic distance. Thus we postulate that viral terminases cleave DNA by the canonical RuvC-like mechanism

    The role of clathrin in post-golgi trafficking in toxoplasma gondii

    Get PDF
    Apicomplexan parasites are single eukaryotic cells with a highly polarised secretory system that contains unique secretory organelles (micronemes and rhoptries) that are required for host cell invasion. In contrast, the role of the endosomal system is poorly understood in these parasites. With many typical endocytic factors missing, we speculated that endocytosis depends exclusively on a clathrin-mediated mechanism. Intriguingly, in Toxoplasma gondii we were only able to observe the endogenous clathrin heavy chain 1 (CHC1) at the Golgi, but not at the parasite surface. For the functional characterisation of Toxoplasma gondii CHC1 we generated parasite mutants conditionally expressing the dominant negative clathrin Hub fragment and demonstrate that CHC1 is essential for vesicle formation at the trans-Golgi network. Consequently, the functional ablation of CHC1 results in Golgi aberrations, a block in the biogenesis of the unique secretory microneme and rhoptry organelles, and of the pellicle. However, we found no morphological evidence for clathrin mediating endocytosis in these parasites and speculate that they remodelled their vesicular trafficking system to adapt to an intracellular lifestyle

    Interleukin-17D and Nrf2 mediate initial innate immune cell recruitment and restrict MCMV infection.

    Get PDF
    Innate immune cells quickly infiltrate the site of pathogen entry and not only stave off infection but also initiate antigen presentation and promote adaptive immunity. The recruitment of innate leukocytes has been well studied in the context of extracellular bacterial and fungal infection but less during viral infections. We have recently shown that the understudied cytokine Interleukin (IL)-17D can mediate neutrophil, natural killer (NK) cell and monocyte infiltration in sterile inflammation and cancer. Herein, we show that early immune cell accumulation at the peritoneal site of infection by mouse cytomegalovirus (MCMV) is mediated by IL-17D. Mice deficient in IL-17D or the transcription factor Nuclear factor (erythroid-derived 2)-like 2 (Nrf2), an inducer of IL-17D, featured an early decreased number of innate immune cells at the point of viral entry and were more susceptible to MCMV infection. Interestingly, we were able to artificially induce innate leukocyte infiltration by applying the Nrf2 activator tert-butylhydroquinone (tBHQ), which rendered mice less susceptible to MCMV infection. Our results implicate the Nrf2/IL-17D axis as a sensor of viral infection and suggest therapeutic benefit in boosting this pathway to promote innate antiviral responses

    Calmodulin-like proteins localized to the conoid regulate motility and cell invasion by Toxoplasma gondii

    Get PDF
    Toxoplasma gondii contains an expanded number of calmodulin (CaM)-like proteins whose functions are poorly understood. Using a combination of CRISPR/Cas9-mediated gene editing and a plant-like auxin-induced degron (AID) system, we examined the roles of three apically localized CaMs. CaM1 and CaM2 were individually dispensable, but loss of both resulted in a synthetic lethal phenotype. CaM3 was refractory to deletion, suggesting it is essential. Consistent with this prediction auxin-induced degradation of CaM3 blocked growth. Phenotypic analysis revealed that all three CaMs contribute to parasite motility, invasion, and egress from host cells, and that they act downstream of microneme and rhoptry secretion. Super-resolution microscopy localized all three CaMs to the conoid where they overlap with myosin H (MyoH), a motor protein that is required for invasion. Biotinylation using BirA fusions with the CaMs labeled a number of apical proteins including MyoH and its light chain MLC7, suggesting they may interact. Consistent with this hypothesis, disruption of MyoH led to degradation of CaM3, or redistribution of CaM1 and CaM2. Collectively, our findings suggest these CaMs may interact with MyoH to control motility and cell invasion

    Improved Survival, Vascular Differentiation and Wound Healing Potential of Stem Cells Co-Cultured with Endothelial Cells

    Get PDF
    In this study, we developed a methodology to improve the survival, vascular differentiation and regenerative potential of umbilical cord blood (UCB)-derived hematopoietic stem cells (CD34+ cells), by co-culturing the stem cells in a 3D fibrin gel with CD34+-derived endothelial cells (ECs). ECs differentiated from CD34+ cells appear to have superior angiogenic properties to fully differentiated ECs, such as human umbilical vein endothelial cells (HUVECs). Our results indicate that the pro-survival effect of CD34+-derived ECs on CD34+ cells is mediated, at least in part, by bioactive factors released from ECs. This effect likely involves the secretion of novel cytokines, including interleukin-17 (IL-17) and interleukin-10 (IL-10), and the activation of the ERK 1/2 pathway in CD34+ cells. We also show that the endothelial differentiation of CD34+ cells in co-culture with CD34+-derived ECs is mediated by a combination of soluble and insoluble factors. The regenerative potential of this co-culture system was demonstrated in a chronic wound diabetic animal model. The co-transplantation of CD34+ cells with CD34+-derived ECs improved the wound healing relatively to controls, by decreasing the inflammatory reaction and increasing the neovascularization of the wound
    • …
    corecore