248 research outputs found

    Interplay between carotenoids, abscisic acid and jasmonate guides the compatible rice-Meloidogyne graminicola interaction

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    In this study, we have characterized the role of carotenoids and chlorophyll in the compatible interaction between the sedentary root knot nematode (RKN) Meloidogyne graminicola and the monocot model plant rice (Oryza sativa). Previous transcriptome data showed a differential expression of carotenoid and chlorophyll biosynthesis genes in nematode-induced giant cells and gall tissue. Metabolite measurement showed that galls indeed accumulate chlorophyll a, b and carotenoids, as well as the hormone abscisic acid (ABA). When ABA was externally applied on rice plants, or when ABA-biosynthesis was inhibited, a significant increase in gall formation and nematode development was found, showing the complex role of ABA in this interaction. ABA application suppressed jasmonic acid (JA) levels in the plants, while ABA-biosynthesis inhibition lead to increased JA levels confirming an antagonism between ABA and JA in rice roots. In addition, combined applications of ABA and JA showed that the ABA-effect can overcome JA-induced defense. Based on these observations, we hypothesized that the accumulation of chlorophyll and carotenoid precursors would be beneficial to nematode infection. Indeed, when chemically blocking the carotenoid biosynthesis pathway at different steps, which leads to differential accumulation of carotenoids and chlorophyll in the plants, a positive and clear link between accumulation of carotenoids and chlorophyll and rice susceptibility to RKN was detected

    Spider Silk- Hydrogels, Lyogels, Sponges

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    Spider silk is stronger than Kevlar and more elastic than nylon. These characteristics have led scientists to attempt mass production and world renowned research of the strongest fiber on earth and one of the strongest materials known to man. Only recently has spider silk been artificially produced in large enough quantities to branch out to its endless possibilities. Utah State University\u27s USTAR program has used transgenic goats to produce spider silk protein within their milk. Once these proteins are extracted from the goat\u27s milk it can be restructured in to fibers, adhesives, hydrogels, and coatings. Spider silk has opened the potential for aqueous bases protein materials. Spider silk has been dissolved in aqueous solutions and hydrogels, lyogels, and sponges have been produced. With an aqueous based solution we have determined each of these materials to be biocompatible through immortalized cell culture. This opens a broad range of biomedical uses for each of these materials. We determined the mechanical strength, structural stability, diffusion rate, and drug release effectiveness of these materials. Hydrogels are a gelatinous material composes of mostly water. Their molecular rearrangement can be altered with the incorporation of different post treatments. Lyogels are lyophilized hydrogels that are composed of mostly air and spider silk protein. Sponges are the result of hydrogels that have been frozen in water then allowed to thaw. The properties of the hydrogels, lyogels, and sponges have been characterized by mechanical testing, FTIR, UV spectrometry, and SEM. Through testing and exploration hydrogels have been loaded with antibiotics and much has been learned about the rates of drug release and diffusion through the gels. Although the research on sponges is very new, great strides have been made in showing that they have potential in the biomedical industry especially with their ability to be completely dehydrated then rehydrated again. These different materials can potentially be applied to many different healing applications. The structure and capability of hydrogels, lyogels, and sponges to withstand compression have been studied for all materials. Though each material is related and similar they all have vastly different mechanical properties that give each material distinct properties and capabilities to achieve different tasks

    Jasmonate-induced defense mechanisms in the belowground antagonistic interaction between Pythium arrhenomanes and Meloidogyne graminicola in rice

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    Next to their essential roles in plant growth and development, phytohormones play a central role in plant immunity against pathogens. In this study we studied the previously reported antagonism between the plant-pathogenic oomycete Pythium arrhenomanes and the root-knot nematode Meloidogyne graminicola, two root pathogens that co-occur in aerobic rice fields. In this manuscript, we investigated if the antagonism is related to imbalances in plant hormone levels, which could be involved in activation of plant defense. Hormone measurements and gene expression analyses showed that the jasmonate (JA) pathway is induced early upon P. arrhenomanes infection. Exogenous application of methyl-jasmonate (MeJA) on the plant confirmed that JA is needed for basal defense against both P. arrhenomanes and M. graminicola in rice. Whereas M. graminicola suppresses root JA levels to increase host susceptibility, Pythium inoculation boosts JA in a manner that prohibits JA repression by the nematode in double-inoculated plants. Exogenous MeJA supply phenocopied the defense-inducing capacity of Pythium against the root-knot nematode, whereas the antagonism was weakened in JA-insensitive mutants. Transcriptome analysis confirmed upregulation of JA biosynthesis and signaling genes upon P. arrhenomanes infection, and additionally revealed induction of genes involved in biosynthesis of diterpenoid phytoalexins, consistent with strong activation of the gene encoding the JA-inducible transcriptional regulator DITERPENOID PHYTOALEXIN FACTOR. Altogether, the here-reported data indicate an important role for JA-induced defense mechanisms in this antagonistic interaction. Next to that, our results provide evidence for induced expression of genes encoding ERF83, and related PR proteins, as well as auxin depletion in P. arrhenomanes infected rice roots, which potentially further contribute to the reduced nematode susceptibility seen in double-infected plants

    Biodegradability of organic matter associated with sewer sediments during first flush

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    The high pollution load in wastewater at the beginning of a rain event is commonly known to originate from the erosion of sewer sediments due to the increased flow rate under storm weather conditions. It is essential to characterize the biodegradability of organic matter during a storm event in order to quantify the effect it can have further downstream to the receiving water via discharges from Combined Sewer Overflow (CSO). The approach is to characterize the pollutograph during first flush. The pollutograph shows the variation in COD and TSS during a first flush event. These parameters measure the quantity of organic matter present. However these parameters do not indicate detailed information on the biodegradability of the organic matter. Such detailed knowledge can be obtained by dividing the total COD into fractions with different microbial properties. To do so oxygen uptake rate (OUR) measurements on batches of wastewater have shown itself to be a versatile technique. Together with a conceptual understanding of the microbial transformation taking place, OUR measurements lead to the desired fractionation of the COD. OUR results indicated that the highest biodegradability is associated with the initial part of a storm event. The information on physical and biological processes in the sewer can be used to better manage sediment in sewers which can otherwise result in depletion of dissolved oxygen in receiving waters via discharges from CSOS

    ARAKNIPRINT: 3D Printing of Synthetic Spider Silk to Produce Biocompatible and Resorbable Biomaterials

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    At 3.07billionin2013,the3Dprintingindustrywasprojectedtoreach3.07 billion in 2013, the 3D printing industry was projected to reach 12.8 billion in 2018 and exceed 21billionby2020(WohlersandCaffrey,2013).Alucrativepartofthisexpandingindustryincludesprintingbiocompatiblemedicalimplants,devices,andtissuescaffolds.Acommonproblemencounteredwithtraditionaldevices,implants,andtissuescaffoldsisthattheyarenotuniquetothepatientandlackthenecessarystrengthandbiocompatibility.Toanswerthesedemands,customizabledevicesarebeingproducedfrompatientmedicalscansandCADdesignsusing3Dprinters.Theseprinterstraditionallyusethermoplasticsbecauseoftheeasewithwhichtheyareprinted.Theseplasticsaretypicallyregardedasbiocompatiblebutcandegradetolessbiocompatibleformsinthebodyandleavetheimplantsite,causinginflammatoryandforeignbodyresponses.Becauseoftheseproblems,therehasbeenafocusondevelopingnewbiomaterialsformedical3Dprinters.SpidersilkisanaturalproteinpolymerthatisstrongerthansteelorKevlarandmoreelasticthannylon.Ithasalsobeenshowntobemorebiocompatiblethanmanymaterialscurrentlyusedin3Dprinters.Inpreviousanimalstudies,spidersilkhasproventonotcauseaninflammatoryresponseupondegradationwhichmakesitadesiredresorbableimplantmaterial(Lewis,2006).A3Dprintersystemcomprisedofasyntheticspidersilkresinandamodified3Dprinterwasdeveloped.Afusedfilament3Dprinter,purchasedforunder21 billion by 2020 (Wohlers and Caffrey, 2013). A lucrative part of this expanding industry includes printing biocompatible medical implants, devices, and tissue scaffolds. A common problem encountered with traditional devices, implants, and tissue scaffolds is that they are not unique to the patient and lack the necessary strength and biocompatibility. To answer these demands, customizable devices are being produced from patient medical scans and CAD designs using 3D printers. These printers traditionally use thermoplastics because of the ease with which they are printed. These plastics are typically regarded as biocompatible but can degrade to less biocompatible forms in the body and leave the implant site, causing inflammatory and foreign body responses. Because of these problems, there has been a focus on developing new biomaterials for medical 3D printers. Spider silk is a natural protein polymer that is stronger than steel or Kevlar and more elastic than nylon. It has also been shown to be more biocompatible than many materials currently used in 3D printers. In previous animal studies, spider silk has proven to not cause an inflammatory response upon degradation which makes it a desired resorbable implant material (Lewis, 2006). A 3D printer system comprised of a synthetic spider silk resin and a modified 3D printer was developed. A fused filament 3D printer, purchased for under 600, was modified with a custom syringe pump design. This syringe pump allowed for the extrusion of spider silk proteins through a needle, producing defined structures. Cell studies were performed on these structures which showed favorable cell attachment and growth. Capable of entering various emerging industries, spider silk offers an alternative in 3D printed biomaterials

    External validation of a prognostic model incorporating quantitative PET image features in esophageal cancer

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    Aim Enhanced prognostic models are required to improve risk stratification of patients with oesophageal cancer so treatment decisions can be optimised. The primary aim was to externally validate a published prognostic model incorporating PET image features. Transferability of the model was compared using only clinical variables. Methods This was a Transparent Reporting of a multivariate prediction model for Individual Prognosis Or Diagnosis (TRIPOD) type 3 study. The model was validated against patients treated with neoadjuvant chemoradiotherapy according to the Neoadjuvant chemoradiotherapy plus surgery versus surgery alone for oesophageal or junctional cancer (CROSS) trial regimen using pre- and post-harmonised image features. The Kaplan–Meier method with log-rank significance tests assessed risk strata discrimination. A Cox proportional hazards model assessed model calibration. Primary outcome was overall survival (OS). Results Between 2010 and 2015, 449 patients were included in the development (n = 302), internal validation (n = 101) and external validation (n = 46) cohorts. No statistically significant difference in OS between patient quartiles was demonstrated in prognostic models incorporating PET image features (X2 = 1.42, df = 3, p = 0.70) or exclusively clinical variables (age, disease stage and treatment; X2 = 1.19, df = 3, p = 0.75). The calibration slope β of both models was not significantly different from unity (p = 0.29 and 0.29, respectively). Risk groups defined using only clinical variables suggested differences in OS, although these were not statistically significant (X2 = 0.71, df = 2, p = 0.70). Conclusion The prognostic model did not enable significant discrimination between the validation risk groups, but a second model with exclusively clinical variables suggested some transferable prognostic ability. PET harmonisation did not significantly change the results of model validation
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