14 research outputs found
Sporisorium reilianum Infection Changes Inflorescence and Branching Architectures of Maize
No full textAbstractSporisorium reilianum is a biotrophic maize (Zea mays) pathogen of increasing economic importance. Symptoms become obvious at flowering time, when the fungus causes spore formation and phyllody in the inflorescences. To understand how S. reilianum changes the inflorescence and floral developmental program of its host plant, we investigated the induced morphological and transcriptional alterations. S. reilianum infection promoted the outgrowth of subapical ears, suggesting that fungal presence suppressed apical dominance. Female inflorescences showed two distinct morphologies, here termed “leafy ear” and “eary ear.” In leafy ears, all floral organs were replaced by vegetative organs. In eary ears, modified carpels enclosed a new female inflorescence harboring additional female inflorescences at every spikelet position. Similar changes in meristem fate and organ identity were observed in the tassel of infected plants, which formed male inflorescences at spikelet positions. Thus, S. reilianum triggered a loss of organ and meristem identity and a loss of meristem determinacy in male and female inflorescences and flowers. Microarray analysis showed that these developmental changes were accompanied by transcriptional regulation of genes proposed to regulate floral organ and meristem identity as well as meristem determinacy in maize. S. reilianum colonization also led to a 30% increase in the total auxin content of the inflorescence as well as a dramatic accumulation of reactive oxygen species. We propose a model describing the architectural changes of infected inflorescence as a consequence of transcriptional, hormonal, and redox modulation, which will be the basis for further molecular investigation of the underlying mechanism of S. reilianum-induced alteration of floral development.</jats:p
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No full textThe biotrophic fungus Ustilago maydis causes smut disease in maize with characteristic tumor formation and anthocyanin induction. Here, we show that anthocyanin biosynthesis is induced by the virulence promoting secreted effector protein Tin2. Tin2 protein functions inside plant cells where it interacts with maize protein kinase ZmTTK1. Tin2 masks a ubiquitin-proteasome degradation motif in ZmTTK1, thus stabilizing the active kinase. Active ZmTTK1 controls activation of genes in the anthocyanin biosynthesis pathway. Without Tin2, enhanced lignin biosynthesis is observed in infected tissue and vascular bundles show strong lignification. This is presumably limiting access of fungal hyphae to nutrients needed for massive proliferation. Consistent with this assertion, we observe that maize brown midrib mutants affected in lignin biosynthesis are hypersensitive to U. maydis infection. We speculate that Tin2 rewires metabolites into the anthocyanin pathway to lower their availability for other defense responses
WITHDRAWN: Structural and mechanistic studies of hydroperoxide conversions catalyzed by a CYP74 clan epoxy alcohol synthase from amphioxus (Branchiostoma floridae)
No full textThis manuscript has been withdrawn by the Author
Population pharmacokinetics of subcutaneous C1-inhibitor for prevention of attacks in patients with hereditary angioedema
No full textBackground: Long-term prophylaxis with subcutaneous (SC) administration of a highly concentrated plasma-derived C1-esterase inhibitor (C1-INH) formulation was recently approved by the Food and Drug Administration for hereditary angioedema (HAE) attack prevention. Objective: To characterize the population pharmacokinetics of C1-INH (SC) (HAEGARDA ® ; CSL Behring) in healthy volunteers and HAE patients, and assess the variability and influence of covariates on pharmacokinetics. Methods: C1-INH functional activity data obtained after administration of various C1-INH (intravenous; IV) and C1-INH (SC) doses from 1 study in healthy volunteers (n = 16) and 2 studies in subjects with HAE (n = 108) were pooled to develop a population pharmacokinetic model (NONMEM v7.2). Pharmacokinetic parameters derived from steady-state simulations based on the final model were also evaluated. Results: C1-INH functional activity following C1-INH (SC) administration was described by a linear one-compartment model with first-order absorption and elimination, with inter-individual variability in all parameters tested. The mean population bioavailability of C1-INH (SC), and pharmacokinetic parameters for clearance (CL), volume of distribution, and absorption rate were estimated to be ~43%, 1.03 mL/hour/kg, 0.05 L/kg and 0.0146 hour −1 , respectively. The effect of bodyweight on CL of C1-INH functional activity was included in the final model, estimated to be 0.74. Steady-state simulations of C1-INH functional activity vs time profiles in 1000 virtual HAE patients revealed higher minimum functional activity (C trough ) levels after twice-weekly dosing with 40 IU/kg (~40%) and 60 IU/kg (~48%) compared with 1000 IU IV (~30%). Based on the population pharmacokinetic model, the median time to peak concentration was ~59 hours and the median apparent plasma half-life was ~69 hours. Conclusions and Clinical Relevance: Twice-weekly bodyweight-adjusted dosing of C1-INH (SC) exhibits linear pharmacokinetics and dose-dependent increases in C trough levels at each dosing interval. In this analysis, SC dosing led to maintenance of higher C trough levels than IV dosing
Pharmacokinetics and pharmacodynamics of a recombinant fusion protein linking activated coagulation factor VII with human albumin (rVIIa-FP) in patients with congenital FVII deficiency
No full textObjectives: Recombinant fusion protein linking activated factor VIIa to human albumin (rVIIa-FP) is a therapeutic option designed to prevent and treat bleeding events in patients with congenital FVII deficiency with reduced infusion frequency compared to current FVII treatments. This study characterized the pharmacokinetics (PK) and pharmacodynamics (PD) of rVIIa-FP.
Methods: A phase I multicenter, randomized, open-label, parallel-arm, single-dose study (NCT02470871) was conducted in nine patients with severe congenital FVII deficiency. Patients received their routine FVII product (30 IU/kg plasma-derived FVII [pdFVII] or 25 μg/kg recombinant activated FVII (rFVIIa) [eptacog alfa]), and were then randomly assigned to receive 100 or 300 μg/kg of rVIIa-FP. Blood samples for PK and PD assessments were drawn up to 48 hr after administration. FVIIa activity was determined using a one-stage clotting assay. PD parameters were derived from thrombin generation testing, using the Nijmegen hemostasis assay.
Results: rVIIa-FP showed improved PK compared to rFVIIa, with 2- to 3-fold longer t1/2 and 4- to 8-fold lower clearance. Analysis of PD data showed a sustained suppression of lag time below 4.5 min (upper limit of healthy people) for rVIIa-FP compared to rFVIIa. AUEC and ECmax were similar across the two dose groups of rVIIa-FP and rFVIIa.
Discussion: rVIIa-FP was well tolerated in patients with congenital FVII deficiency, showed a longer half-life and lower clearance compared to rFVIIa, and lag time remaining within healthy ranges for ≥8 hr.
Conclusion: These results warrant further investigation into the efficacy of rVIIa-FP to control and prevent bleeding in patients with FVII deficiency
The maize lipoxygenase, ZmLOX10, mediates green leaf volatile, jasmonate and herbivore‐induced plant volatile production for defense against insect attack
No full textThis is the peer reviewed version of the following article: [Christensen, S. A., Nemchenko, A., Borrego, E., Murray, I., Sobhy, I. S., Bosak, L., DeBlasio, S., Erb, M., Robert, C. A. M., Vaughn, K. A., Herrfurth, C., Tumlinson, J., Feussner, I., Jackson, D., Turlings, T. C. J., Engelberth, J., Nansen, C., Meeley, R., Kolomiets, M. V. (2013). The maize lipoxygenase, ZmLOX10, mediates green leaf volatile, jasmonate and herbivore‐induced plant volatile production for defense against insect attack. The Plant Journal, 74(1), 59-73], which has been published in final form at [https://doi.org/10.1111/tpj.12101]. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. This article may not be enhanced, enriched or otherwise transformed into a derivative work, without express permission from Wiley or by statutory rights under applicable legislation. Copyright notices must not be removed, obscured or modified. The article must be linked to Wiley’s version of record on Wiley Online Library and any embedding, framing or otherwise making available the article or pages thereof by third parties from platforms, services and websites other than Wiley Online Library must be prohibited.Fatty acid derivatives are of central importance for plant immunity against insect herbivores; however, major regulatory genes and the signals that modulate these defense metabolites are vastly understudied, especially in important agro-economic monocot species. Here we show that products and signals derived from a single Zea mays (maize) lipoxygenase (LOX), ZmLOX10, are critical for both direct and indirect defenses to herbivory. We provide genetic evidence that two 13-LOXs, ZmLOX10 and ZmLOX8, specialize in providing substrate for the green leaf volatile (GLV) and jasmonate (JA) biosynthesis pathways, respectively. Supporting the specialization of these LOX isoforms, LOX8 and LOX10 are localized to two distinct cellular compartments, indicating that the JA and GLV biosynthesis pathways are physically separated in maize. Reduced expression of JA biosynthesis genes and diminished levels of JA in lox10 mutants indicate that LOX10-derived signaling is required for LOX8-mediated JA. The possible role of GLVs in JA signaling is supported by their ability to partially restore wound-induced JA levels in lox10 mutants. The impaired ability of lox10 mutants to produce GLVs and JA led to dramatic reductions in herbivore-induced plant volatiles (HIPVs) and attractiveness to parasitoid wasps. Because LOX10 is under circadian rhythm regulation, this study provides a mechanistic link to the diurnal regulation of GLVs and HIPVs. GLV-, JA- and HIPV-deficient lox10 mutants display compromised resistance to insect feeding, both under laboratory and field conditions, which is strong evidence that LOX10-dependent metabolites confer immunity against insect attack. Hence, this comprehensive gene to agro-ecosystem study reveals the broad implications of a single LOX isoform in herbivore defense.UnfundedAAM supplied by author and uploaded to ChesterRep 07/11/202
ERF5 and ERF6 play redundant roles as positive regulators of JA/Et-mediated defense against botrytis cinerea in arabidopsis
No full textCopyright @ 2012 Moffat et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.The ethylene response factor (ERF) family in Arabidopsis thaliana comprises 122 members in 12 groups, yet the biological functions of the majority remain unknown. Of the group IX ERFs, the IXc subgroup has been studied the most, and includes ERF1, ERF14 and ORA59, which play roles in plant innate immunity. Here we investigate the biological functions of two members of the less studied IXb subgroup: ERF5 and ERF6. In order to identify potential targets of these transcription factors, microarray analyses were performed on plants constitutively expressing either ERF5 or ERF6. Expression of defense genes, JA/Et-responsive genes and genes containing the GCC box promoter motif were significantly upregulated in both ERF5 and ERF6 transgenic plants, suggesting that ERF5 and ERF6 may act as positive regulators of JA-mediated defense and potentially overlap in their function. Since defense against necrotrophic pathogens is generally mediated through JA/Et-signalling, resistance against the fungal necrotroph Botrytis cinerea was examined. Constitutive expression of ERF5 or ERF6 resulted in significantly increased resistance. Although no significant difference in susceptibility to B. cinerea was observed in either erf5 or erf6 mutants, the erf5 erf6 double mutant showed a significant increase in susceptibility, which was likely due to compromised JA-mediated gene expression, since JA-induced gene expression was reduced in the double mutant. Taken together these data suggest that ERF5 and ERF6 play positive but redundant roles in defense against B. cinerea. Since mutual antagonism between JA/Et and salicylic acid (SA) signalling is well known, the UV-C inducibility of an SA-inducible gene, PR-1, was examined. Reduced inducibilty in both ERF5 and ERF6 constitutive overexepressors was consistent with suppression of SA-mediated signalling, as was an increased susceptibility to avirulent Pseudomonas syringae. These data suggest that ERF5 and ERF6 may also play a role in the antagonistic crosstalk between the JA/Et and SA signalling pathways.This work was funded by the Biotechnology and Biological Sciences Research Council (BBSRC) UK (studentship BBS/S/B/2003/12908 and BBS/S/K/2003/10126
Phage anti-CRISPR control by an RNA- and DNA-binding helix–turn–helix protein
No full textIn all organisms, regulation of gene expression must be adjusted to meet cellular requirements and frequently involves helix-turn-helix (HTH) domain proteins . For instance, in the arms race between bacteria and bacteriophages, rapid expression of phage anti-CRISPR (acr) genes upon infection enables evasion from CRISPR-Cas defence; transcription is then repressed by an HTH-domain-containing anti-CRISPR-associated (Aca) protein, probably to reduce fitness costs from excessive expression . However, how a single HTH regulator adjusts anti-CRISPR production to cope with increasing phage genome copies and accumulating acr mRNA is unknown. Here we show that the HTH domain of the regulator Aca2, in addition to repressing Acr synthesis transcriptionally through DNA binding, inhibits translation of mRNAs by binding conserved RNA stem-loops and blocking ribosome access. The cryo-electron microscopy structure of the approximately 40 kDa Aca2-RNA complex demonstrates how the versatile HTH domain specifically discriminates RNA from DNA binding sites. These combined regulatory modes are widespread in the Aca2 family and facilitate CRISPR-Cas inhibition in the face of rapid phage DNA replication without toxic acr overexpression. Given the ubiquity of HTH-domain-containing proteins, it is anticipated that many more of them elicit regulatory control by dual DNA and RNA binding. [Abstract copyright: © 2024. The Author(s), under exclusive licence to Springer Nature Limited.
Effect of 1- and 2-Month High-Dose Alpha-Linolenic Acid Treatment on 13C-Labeled Alpha-Linolenic Acid Incorporation and Conversion in Healthy Subjects
No full textScope: The study aims at identifying 1) the most sensitive compartment among plasma phospholipids, erythrocytes, and LDL for studying alpha‐linolenic acid (ALA) conversion, and 2) whether ALA incorporation and conversion is saturable after administration of 13C‐labeled ALA‐rich linseed oil (LO). The effect of a daily intake of 7 g nonlabeled LO (>43% w/w ALA) for 1 month after bolus administration of 7 g 13C‐labeled LO on day 1, and for 2 months after bolus administration of 7 g 13C‐labeled LO on day 1 and day 29 on 13C‐ALA incorporation and conversion into its higher homologs is investigated in healthy volunteers.
Methods and results: Incorporation and conversion of LO‐derived 13C‐labeled ALA is quantified by applying compartmental modeling. After bolus administration, a fractional conversion of approximately 30% from 13C‐ALA to 13C‐DHA is calculated as reflected by the LDL compartment. Treatment with LO for 8 weeks induces a mean reduction of 13C‐ALA conversion to 13C‐DHA by 48% as reflected by the LDL compartment, and a mean reduction of the 13C‐ALA incorporation into LDL by 46%.
Conclusion: A 2‐month dietary intake of a high dose of LO is sufficient to reach saturation of ALA incorporation into LDL particles, which are responsible for ALA distribution in the body.© 2018 The Author
