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INTRODUCTION: Hematocrit monitoring during continuous renal replacement therapy (CRRT) allows the continuous estimation of relative blood volume (RBV). This may enable early detection of intravascular volume depletion prior to clinical sequelae. We aimed to investigate the feasibility of extended RBV monitoring and its epidemiology during usual CRRT management by clinicians unaware of RBV. Moreover, we studied the association between changes in RBV and net ultrafiltration (NUF) rates. METHODS: In a cohort of adult intensive care unit patients receiving CRRT, we continuously monitored hematocrit and RBV using a pre-filter non-invasive optical sensor. We analyzed temporal changes in RBV and investigated the association between RBV change and NUF rates, using the classification of NUF rates into low, moderate, or high based on predefined cut-offs. RESULTS: We obtained >60,000 minute-by-minute measurements in >1,000 CRRT hours in 36 patients. The median RBV change was negative (decrease) in 69% of patients and the median peak change in RBV was -9.3% (IQR -3.9% to -14.3%). Moreover, the median RBV decreased from baseline by >5% in 40.2% of measurements and by >10% in 20.6% of measurements. Finally, RBV decreased significantly more when patients received a high NUF rate (>1.75 ml/kg/h) compared to low or moderate NUF rates (5.32% vs 1.93% or 1.97%, p<0.001). CONCLUSION: Continuous hematocrit and RBV monitoring during CRRT was feasible. RBV decreased significantly during CRRT, and decreases were greater with higher NUF rates. RBV monitoring may help optimize NUF management and prevent the occurrence of intravascular volume depletion.
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Pentacyclic triterpenoids, recognized for their natural bioactivity, display complex spatiotemporal accumulation patterns within the ecological model plant Nicotiana attenuata. Despite their ecological importance, the underlying biosynthetic enzymes and functional attributes of triterpenoid synthesis in N. attenuata remain unexplored. Here, we show that three cytochrome P450 monooxygenases (NaCYP716A419, NaCYP716C87, and NaCYP716E107) from N. attenuata oxidize the pentacyclic triterpene skeleton, as evidenced by heterologous expression in Nicotiana benthamiana. NaCYP716A419 catalyzed a consecutive three-step oxidation reaction at the C28 position of ß-amyrin/lupeol/lupanediol, yielding the corresponding alcohol, aldehyde, and carboxylic acid. NaCYP716C87 hydroxylated the C2α position of ß-amyrin/lupeol/lupanediol/erythrodiol/oleanolic acid/betulinic acid, while NaCYP716E107 hydroxylated the C6ß position of ß-amyrin/oleanolic acid. The genes encoding these three CYP716 enzymes are highly expressed in flowers and respond to induction by ABA, MeJA, SA, GA3, and abiotic stress treatments. Using VIGS technology, we revealed that silencing of NaCYP716A419 affects the growth and reproduction of N. attenuata, suggesting the ecological significance of these specialized metabolite biosynthetic steps.
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The feeding of piercing-sucking insect herbivores often elicits changes in their host plants that benefit the insect.1 In addition to thwarting a host's defense responses, these phloem-feeding insects may manipulate source-sink signaling so as to increase resources consumed.2,3 To date, the molecular mechanisms underlying herbivore-induced resource reallocation remain less investigated. Brown planthopper (BPH), an important rice pest, feeds on the phloem and oviposits into leaf sheaths. BPH herbivory increases sugar accumulations 5-fold in the phloem sap of leaf sheaths and concurrently induces the expression of two clade III SWEET genes, SWEET13 and SWEET14, in leaf tissues, but not in leaf sheaths of attacked rice plants. Mutations of both genes by genome editing attenuate resistance to BPH without alterations of known chemical and physical defense responses. Moreover, BPH-elicited sugar levels in the phloem sap were significantly reduced in sweet13/14 mutants, which is likely to attenuate BPH feeding behavior on sweet13/14 mutants. In one of the two field seasons tested, the sweet13/14 mutants showed comparable yield to wild types, and in the other season, the mutants demonstrated stronger BPH resistance. These preliminary results suggested that the mutations in these SWEET transporters could enhance BPH resistance without yield penalties. Given that sweet13/14 mutants also exhibit resistance to bacterial blight pathogen, Xanthomonas oryzae pv. oryzae, these SWEET genes could serve as excellent molecular targets for the breeding of resistant rice cultivars.
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Hemípteros , Oryza , Hemípteros/fisiologia , Hemípteros/genética , Hemípteros/microbiologia , Oryza/metabolismo , Oryza/genética , Oryza/microbiologia , Animais , Herbivoria , Floema/metabolismo , Proteínas de Plantas/metabolismo , Proteínas de Plantas/genética , Comportamento Alimentar/fisiologia , Açúcares/metabolismoRESUMO
The phytohormone jasmonate (JA) plays a central role in plant defenses against biotic stressors. However, our knowledge of the JA signaling pathway in rice (Oryza sativa) remains incomplete. Here, we integrated multi-omic data from three tissues to characterize the functional modules involved in organizing JA-responsive genes. In the core regulatory sector, MYC2 transcription factor transcriptional cascades are conserved. in different species but with distinct regulators (e.g. bHLH6 in rice)., in which genes are early expressed across all tissues. In the feedback sector, MYC2 also regulates the expression of JA repressor and catabolic genes, providing negative feedback that truncates the duration of JA responses. For example, the MYC2-regulated NAC (NAM, ATAF1/2 and CUC2) transcription factor genes NAC1, NAC3, and NAC4 encode proteins that repress JA signaling and herbivore resistance. In the tissue-specific sector, many late-expressed genes are associated with the biosynthesis of specialized metabolites that mediate particular defensive functions. For example, the terpene synthase gene TPS35 is specifically induced in the leaf sheath and TPS35 functions in defense against oviposition by brown planthoppers and the attraction of this herbivore's natural enemies. Thus, by characterizing core, tissue-specific, and feedback sectors of JA-elicited defense responses, this work provides a valuable resource for future discoveries of key JA components in this important crop.
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The apocarotenoid strigolactones (SLs) facilitate pre-symbiotic communication between arbuscular mycorrhizal (AM) fungi and plants. Related blumenol-C-glucosides (blumenols), have also been associated with symbiosis, but the cues that are involved in the regulation of blumenol accumulation during AM symbiosis remain unclear. In rice, our analyses demonstrated a strict correlation between foliar blumenol abundance and intraradical fungal colonisation. More specifically, rice mutants affected at distinct stages of the interaction revealed that fungal cortex invasion was required for foliar blumenol accumulation. Plant phosphate status and D14L hormone signalling had no effect, contrasting their known role in induction of SLs. This a proportion of the SL biosynthetic enzymes, D27 and D17, are equally required for blumenol production. These results importantly clarify that, while there is a partially shared biosynthetic pathway between SL and blumenols, the dedicated induction of the related apocarotenoids occurs in response to cues acting at distinct stages during the root colonisation process. However, we reveal that neither SLs nor blumenols are essential for fungal invasion of rice roots.
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Lactonas , Micorrizas , Oryza , Simbiose , Micorrizas/fisiologia , Oryza/microbiologia , Oryza/metabolismo , Oryza/genética , Oryza/fisiologia , Lactonas/metabolismo , Raízes de Plantas/microbiologia , Raízes de Plantas/metabolismo , Reguladores de Crescimento de Plantas/metabolismo , Glucosídeos/metabolismo , Regulação da Expressão Gênica de PlantasRESUMO
Adsorption-based extracorporeal therapies have been subject to technical developments and clinical application for close to five decades. More recently, new technological developments in membrane and sorbent manipulation have made it possible to deliver more biocompatible extracorporeal adsorption therapies to patients with a variety of conditions. There are several key rationales based on physicochemical principles and clinical considerations that justify the application and investigation of such therapies as evidenced by multiple ex-vivo, experimental, and clinical observations. Accordingly, unspecific adsorptive extracorporeal therapies have now been applied to the treatment of a wide array of conditions from poisoning to drug overdoses, to inflammatory states and sepsis, and acute or chronic liver and kidney failure. In response to the rapidly expanding knowledge base and increased clinical evidence, we convened an Acute Disease Quality Initiative (ADQI) consensus conference dedicated to such treatment. The data show that hemoadsorption has clinically acceptable short-term biocompatibility and safety, technical feasibility, and experimental demonstration of specified target molecule removal. Pilot studies demonstrate potentially beneficial effects on physiology and larger studies of endotoxin-based hemoadsorption have identified possible target phenotypes for larger randomized controlled trials (RCTs). Moreover, in a variety of endogenous and exogenous intoxications, removal of target molecules has been confirmed in vivo. However, some studies have raised concerns about harm or failed to deliver benefits. Thus, despite many achievements, modern hemoadsorption remains a novel and experimental intervention with limited data, and a large research agenda.
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Nicotiana attenuata styles preferentially select pollen from among accessions with corresponding expression patterns of NaS-like-RNases (SLRs), and the postpollination ethylene burst (PPEB) is an accurate predictor of seed siring success. However, the ecological consequences of mate selection, its effect on the progeny, and the role of SLRs in the control of ethylene signaling remain unknown. We explored the link between the magnitude of the ethylene burst and expression of the SLRs in a set of recombinant inbred lines (RILs), dissected the genetic underpinnings of mate selection through genome-wide association study (GWAS), and examined its outcome for phenotypes in the next generation. We found that high levels of PPEB are associated with the absence of SLR2 in most of the tested RILs. We identified candidate genes potentially involved in the control of mate selection and showed that pollination of maternal genotypes with their favored pollen donors produces offspring with longer roots. When the maternal genotypes are only able to select against nonfavored pollen donors, the selection for such positive traits is abolished. We conclude that plants' ability of mate choice contributes to measurable changes in progeny phenotypes and is thus likely a target of selection.
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Regulação da Expressão Gênica de Plantas , Fenótipo , Pólen , Ribonucleases , Pólen/genética , Pólen/fisiologia , Ribonucleases/genética , Ribonucleases/metabolismo , Nicotiana/genética , Nicotiana/fisiologia , Etilenos/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Polinização , Estudo de Associação Genômica Ampla , Zigoto/metabolismo , Genótipo , EndogamiaRESUMO
BACKGROUND: Historically IV and enteral fluids given during acute kidney injury (AKI) were restricted before the introduction of continuous renal replacement therapies (CRRTs) when more liberal fluids improved nutrition for the critically ill. However, fluid accumulation can occur when higher volumes each day are not considered in the fluid balance prescribing and the NET ultrafiltration (NUF) volume target. KEY MESSAGES: The delivered hours of CRRT each day are vital for achievement of fluid balance and time off therapy makes the task more challenging. Clinicians inexperienced with CRRT make this aspect of AKI management a focus of rounding with senior oversight, clear communication, and "precision" a clinical target. Sepsis-associated AKI can be a complex patient where resuscitation and admission days are with a positive fluid load and replacement mind set. Subsequent days in ICU requires fluid regulation, removal, with a comprehensive multilayered assessment before prescribing the daily fluid balance target and the required hourly NET plasma water removal rate (NUF rate). Future machines may include advanced software, new alarms - display metrics, messages and association with machine learning and "AKI models" for setting, monitoring, and guaranteeing fluid removal. This could also link to current hardware such as on-line blood volume assessment with continuous haematocrit measurement. SUMMARY: Fluid balance in the acutely ill is a challenge where forecasting and prediction are necessary. NUF rate and volume each hour should be tracked and adjusted to achieve the daily target. This requires human and machine connections.
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Injúria Renal Aguda , Terapia de Substituição Renal Contínua , Equilíbrio Hidroeletrolítico , Humanos , Terapia de Substituição Renal Contínua/métodos , Injúria Renal Aguda/terapia , Hidratação/métodos , Estado Terminal , Sepse/terapiaRESUMO
Plant specialized metabolites (PSMs) are variably distributed across taxa, tissues, and ecological contexts; this variability has inspired many theories about PSM function, which, to date, remain poorly tested because predictions have outpaced the available data. Advances in mass spectrometry-based metabolomics have enabled unbiased PSM profiling, and molecular biology techniques have produced PSM-free plants; the combination of these methods has accelerated our understanding of the complex ecological roles that PSMs play in plants. Synthetic biology techniques and workflows are producing high-value, structurally complex PSMs in quantities and purities sufficient for both medicinal and functional studies. These workflows enable the reengineering of PSM transport, externalization, structural diversity, and production in novel taxa, facilitating rigorous tests of long-standing theoretical predictions about why plants produce so many different PSMs in particular tissues and ecological contexts. Plants use their chemical prowess to solve ecological challenges, and synthetic biology workflows are accelerating our understanding of these evolved functions.
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Plantas , Biologia Sintética , Plantas/metabolismo , MetabolômicaRESUMO
BACKGROUND: Continuous haemoglobin, venous blood oxygen saturation, and haematocrit (Hct) monitoring is currently not applied during continuous renal replacement therapy (CRRT). Such Hct monitoring enables estimation of changes in blood volume as percentage change (ΔBV%) from therapy start time and is incorporated into intermittent haemodialysis machines but not CRRT machines despite its potential to optimise fluid management in CRRT patients. METHODS: To overcome this problem, we used a standalone monitor (CRIT-LINE®IV, Fresenius Medical Care, Concord, USA) with an associated in-line blood chamber (CRIT-LINE®IV Blood Chamber, Fresenius Medical Care, Concord, USA) and designed our own adaptor connection piece (TekMed and Morriset, Melbourne and Brisbane, Australia) to allow these readings at the vascular access outflow and recorded data for estimated Hct and derived ΔBV% during CRRT. RESULTS: We report on this technique with an illustrative case example and 12 h of CRRT data on the fluid loss rate prescribed, hourly net patient fluid loss (range: 0-308 mL/h), mean arterial pressure, norepinephrine dose (range: 5-14 mcg/min), estimated continuous Hct and ΔBV%, and the otherwise undetected diagnosis of an approximate 15 % decrease in blood volume during the CRRT. CONCLUSION: We have described a technical CRRT circuit modification that can facilitate a previously unavailable assessment of fluid shifts during CRRT. Further application in clinical trials is now possible.
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Volume Sanguíneo , Terapia de Substituição Renal Contínua , Humanos , Terapia de Substituição Renal Contínua/métodos , Hematócrito , Monitorização Fisiológica/métodos , Determinação do Volume Sanguíneo/métodos , Masculino , Injúria Renal Aguda/terapia , Injúria Renal Aguda/sangueRESUMO
Laboratory studies have revealed that strigolatone (SL) and karrikin (KAR) signalling mediate responses to abiotic and biotic stresses, and reshape branching architecture that could increase reproductive performance and crop yields. To understand the ecological function of SL and KAR signalling, transgenic lines of wild tobacco Nicotiana attenuata, silenced in SL/KAR biosynthesis/signalling were grown in the glasshouse and in two field plots in the Great Basin Desert in Utah over four field seasons. Of the lines silenced in SL and KAR signalling components (irMAX2, irD14, irKAI2 and irD14 × irKAI2 plants), which exhibited the expected increases in shoot branching, only irMAX2 plants showed a strong leaf-bleaching phenotype when grown in the field. In the field, irMAX2 plants had lower sugar and higher leaf amino acid contents, lower lifetime fitness and were more susceptible to herbivore attack compared to wild-type plants. These irMAX2 phenotypes were not observed in glasshouse-grown plants. Transcriptomic analysis revealed dramatic responses to high-light intensity in irMAX2 leaves in the field: lutein contents decreased, and transcriptional responses to high-intensity light, singlet oxygen and hydrogen peroxide increased. PAR and UV-B manipulations in the field revealed that the irMAX2 bleaching phenotype is reversed by decreasing PAR, but not UV-B fluence. We propose that NaMAX2 functions in high-light adaptation and fitness optimisation by regulating high-light responses independently of its roles in the SL and KAR signalling pathways. The work provides another example of the value of studying the function of genes in the complex environments in which plants evolved, namely nature.
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Nicotiana , Folhas de Planta , Nicotiana/metabolismo , Perfilação da Expressão GênicaRESUMO
Remote sensing of vegetation by spectroscopy is increasingly used to characterize trait distributions in plant communities. How leaves interact with electromagnetic radiation is determined by their structure and contents of pigments, water, and abundant dry matter constituents like lignins, phenolics, and proteins. High-resolution ("hyperspectral") spectroscopy can characterize trait variation at finer scales, and may help to reveal underlying genetic variation-information important for assessing the potential of populations to adapt to global change. Here, we use a set of 360 inbred genotypes of the wild coyote tobacco Nicotiana attenuata: wild accessions, recombinant inbred lines (RILs), and transgenic lines (TLs) with targeted changes to gene expression, to dissect genetic versus non-genetic influences on variation in leaf spectra across three experiments. We calculated leaf reflectance from hand-held field spectroradiometer measurements covering visible to short-wave infrared wavelengths of electromagnetic radiation (400-2500 nm) using a standard radiation source and backgrounds, resulting in a small and quantifiable measurement uncertainty. Plants were grown in more controlled (glasshouse) or more natural (field) environments, and leaves were measured both on- and off-plant with the measurement set-up thus also in more to less controlled environmental conditions. Entire spectra varied across genotypes and environments. We found that the greatest variance in leaf reflectance was explained by between-experiment and non-genetic between-sample differences, with subtler and more specific variation distinguishing groups of genotypes. The visible spectral region was most variable, distinguishing experimental settings as well as groups of genotypes within experiments, whereas parts of the short-wave infrared may vary more specifically with genotype. Overall, more genetically variable plant populations also showed more varied leaf spectra. We highlight key considerations for the application of field spectroscopy to assess genetic variation in plant populations.
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INTRODUCTION: Hemoadsorption has emerged as an adjunctive therapy for sepsis, but its impact on antibiotic levels remains poorly defined. We conducted an in vivo experimental study to investigate the removal of vancomycin and gentamicin during hemoadsorption using the HA380 cartridge, a novel styrene-divinylbenzene copolymer cartridge. METHODS: Six surgically prepared sheep were administered 2 g of vancomycin and 400 mg of gentamicin over 30 min, followed by a continuous infusion of vancomycin (20 mg/h). Hemoadsorption was implemented with a styrene-divinylbenzene copolymer HA380 cartridge at a blood flow of 120 mL/min. The removal ratio, sorbent-based clearance, and the mass removal rate were calculated for each time point. RESULTS: The mean 10-min vancomycin removal ratio exceeded 90% and declined to 68.0% at 30 min; 52.8% at 60 min, and 28.0% by 4 h. Due to constant plasma flow, clearance varied proportionally with the removal ratio. Over 4 hours, the total mass removal was 556 mg (SD 106.3). For gentamicin, the mean 10-min removal ratio was 96.9% and the final ratio at 4 h remained 53.0%, with clearances changing proportionately. The total mass removal of gentamicin was 138 mg (SD 26.6) over 4 h. The sorbent-based clearance of vancomycin was significantly lower than that of gentamicin (Pgroup < 0.0001). CONCLUSION: The novel HA380 sorbent cartridge appears safe and achieves significant vancomycin and gentamicin removal over a four-hour period. This information can be used by clinicians to guide their prescription and consider the additional dosing of at least an extra 25-35% amount in patients receiving HA380 hemoadsorption therapy during sepsis.
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Sepse , Vancomicina , Humanos , Animais , Ovinos , Gentamicinas , Antibacterianos , Sepse/terapia , EstirenosRESUMO
When insect herbivores attack plants, elicitors from oral secretions and regurgitants (OS) enter wounds during feeding, eliciting defense responses. These generally require plant jasmonate (JA) signaling, specifically, a jasmonoyl-L-isoleucine (JA-Ile) burst, for their activation and are well studied in the native tobacco Nicotiana attenuata. We used intraspecific diversity captured in a 26-parent MAGIC population planted in nature and an updated genome assembly to impute natural variation in the OS-elicited JA-Ile burst linked to a mutation in the JA-Ile biosynthetic gene NaJAR4. Experiments revealed that NaJAR4 variants were associated with higher fitness in the absence of herbivores but compromised foliar defenses, with two NaJAR homologues (4 and 6) complementing each other spatially and temporally. From decade-long seed collections of natural populations, we uncovered enzymatically inactive variants occurring at variable frequencies, consistent with a balancing selection regime maintaining variants. Integrative analyses of OS-induced transcriptomes and metabolomes of natural accessions revealed that NaJAR4 is embedded in a nonlinear complex gene coexpression network orchestrating responses to OS, which we tested by silencing four hub genes in two connected coexpressed networks and examining their OS-elicited metabolic responses. Lines silenced in two hub genes (NaGLR and NaFB67) co-occurring in the NaJAR4/6 module showed responses proportional to JA-Ile accumulations; two from an adjacent module (NaERF and NaFB61) had constitutively expressed defenses with high resistance. We infer that mutations with large fitness consequences can persist in natural populations due to compensatory responses from gene networks, which allow for diversification in conserved signaling pathways and are generally consistent with predictions of an omnigene model.
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Redes Reguladoras de Genes , Herbivoria , Herbivoria/genética , MutaçãoRESUMO
MAIN CONCLUSION: Nicotiana attenuata's capacity to interact with arbuscular mycorrhizal fungi influences its intraspecific competitive ability under field and glasshouse conditions, but not its overall community productivity. Arbuscular mycorrhizal (AM) fungi can alter the nutrient status and growth of plants, and they can also affect plant-plant, plant-herbivore, and plant-pathogen interactions. These AM effects are rarely studied in populations under natural conditions due to the limitation of non-mycorrhizal controls. Here we used a genetic approach, establishing field and glasshouse communities of AM-harboring Nicotiana attenuata empty vector (EV) plants and isogenic plants silenced in calcium- and calmodulin-dependent protein kinase expression (irCCaMK), and unable to establish AM symbioses. Performance and growth were quantified in communities of the same (monocultures) or different genotypes (mixed cultures) and both field and glasshouse experiments returned similar responses. In mixed cultures, AM-harboring EV plants attained greater stalk lengths, shoot and root biomasses, clearly out-competing the AM fungal-deficient irCCaMK plants, while in monocultures, both genotypes grew similarly. Competitive ability was also reflected in reproductive traits: EV plants in mixed cultures outperformed irCCaMK plants. When grown in monocultures, the two genotypes did not differ in reproductive performance, though total leaf N and P contents were significantly lower independent of the community type. Plant productivity in terms of growth and seed production at the community level did not differ, while leaf nutrient content of phosphorus and nitrogen depended on the community type. We infer that AM symbioses drastically increase N. attenuata's competitive ability in mixed communities resulting in increased fitness for the individuals harboring AM without a net gain for the community.
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Micorrizas , Micorrizas/fisiologia , Raízes de Plantas , Plantas , Nicotiana/genética , Nicotiana/microbiologia , Biomassa , Fungos/fisiologia , Solo , SimbioseRESUMO
Plants interact with arbuscular mycorrhizal fungi (AMF) and in doing so, change transcript levels of many miRNAs and their targets. However, the identity of an Argonaute (AGO) that modulates this interaction remains unknown, including in Nicotiana attenuata. We examined how the silencing of NaAGO1/2/4/7/and 10 by RNAi influenced plant-competitive ability under low-P conditions when they interact with AMF. Furthermore, the roles of seven miRNAs, predicted to regulate signaling and phosphate homeostasis, were evaluated by transient overexpression. Only NaAGO7 silencing by RNAi (irAGO7) significantly reduced the competitive ability under P-limited conditions, without changes in leaf or root development, or juvenile-to-adult phase transitions. In plants growing competitively in the glasshouse, irAGO7 roots were over-colonized with AMF, but they accumulated significantly less phosphate and the expression of their AMF-specific transporters was deregulated. Furthermore, the AMF-induced miRNA levels were inversely regulated with the abundance of their target transcripts. miRNA overexpression consistently decreased plant fitness, with four of seven-tested miRNAs reducing mycorrhization rates, and two increasing mycorrhization rates. Overexpression of Na-miR473 and Na-miRNA-PN59 downregulated targets in GA, ethylene, and fatty acid metabolism pathways. We infer that AGO7 optimizes competitive ability and colonization by regulating miRNA levels and signaling pathways during a plant's interaction with AMF.
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MicroRNAs , Micorrizas , Nicotiana/metabolismo , Micorrizas/fisiologia , Raízes de Plantas/metabolismo , MicroRNAs/genética , MicroRNAs/metabolismo , Fosfatos/metabolismoRESUMO
Plant defense against herbivores is costly and often associated with growth repression. The phytohormone jasmonate (JA) plays a central role in prioritizing defense over growth during herbivore attack, but the underlying mechanisms remain unclear. When brown planthoppers (BPH, Nilaparvata lugens) attack rice (Oryza sativa), growth is dramatically suppressed. BPH infestation also increases inactive gibberellin (GA) levels and transcripts of GA 2-oxidase (GA2ox) genes, 2 (GA2ox3 and GA2ox7) of which encode enzymes that catalyze the conversion of bioactive GAs to inactive GAs in vitro and in vivo. Mutation of these GA2oxs diminishes BPH-elicited growth restriction without affecting BPH resistance. Phytohormone profiling and transcriptome analyses revealed that GA2ox-mediated GA catabolism was enhanced by JA signaling. The transcript levels of GA2ox3 and GA2ox7 were significantly attenuated under BPH attack in JA biosynthesis (allene oxide cyclase [aoc]) or signaling-deficient (myc2) mutants. In contrast, GA2ox3 and GA2ox7 expression was increased in MYC2 overexpression lines. MYC2 directly binds to the G-boxes in the promoters of both GA2ox genes to regulate their expression. We conclude that JA signaling simultaneously activates defense responses and GA catabolism to rapidly optimize resource allocation in attacked plants and provides a mechanism for phytohormone crosstalk.
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Plant-predator mutualisms have been widely described in nature.1,2 How plants fine-tune their mutualistic interactions with the predators they recruit remains poorly understood. In the wild potato (Solanum kurtzianum), predatory mites, Neoseiulus californicus, are recruited to flowers of undamaged plants but rapidly move downward when the herbivorous mites, Tetranychus urticae, damage leaves. This "up-down" movement within the plant corresponds to the shift of N. californicus from palynivory to carnivory, as they change from feeding on pollen to herbivores when moving between different plant organs. This up-down movement of N. californicus is mediated by the organ-specific emissions of volatile organic compounds (VOCs) in flowers and herbivory-elicited leaves. Experiments with exogenous applications, biosynthetic inhibitors, and transient RNAi revealed that salicylic acid and jasmonic acid signaling in flowers and leaves mediates both the changes in VOC emissions and the up-down movement of N. californicus. This alternating communication between flowers and leaves mediated by organ-specific VOC emissions was also found in a cultivated variety of potato, suggesting the agronomic potential of using flowers as reservoirs of natural enemies in the control of potato pests.
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Ácaros , Tetranychidae , Compostos Orgânicos Voláteis , Animais , Ácaros/fisiologia , Tetranychidae/fisiologia , Folhas de Planta , Flores , Comportamento Predatório/fisiologiaRESUMO
Plants produce chemical defenses that poison insect herbivores or deter their feeding, but herbivores are also accompanied by microbial endosymbionts crucial for their nutrition, reproduction, and fitness. Hence, plant defenses could target a herbivore's beneficial endosymbionts, but this has not yet been demonstrated. Here, we studied flavonoids that are induced when rice is attacked by a phloem-feeding pest, the brown planthopper (BPH), which harbors beneficial yeast-like symbionts (YLS) essential for insect nutrition, such as by remedying deficiencies in sterols. BPH attack dramatically increased sakuranetin accumulations in leaf sheaths and phloem exudates. Sakuranetin is an antifungal phytoalexin derived from the antibacterial precursor, naringenin, via catalysis of naringenin-O-methyltransferase (NOMT). When added to artificial diets, sakuranetin decreased BPH survivorship, suggesting that it functions as an induced defense. Mutation of NOMT abolished sakuranetin accumulation and increased BPH oviposition and hatching rates. High-throughput amplicon sequencing revealed that BPH fed on sakuranetin-deficient nomt lines were enriched in YLS with only minor changes in the bacterial endosymbionts, compared to those feeding on sakuranetin-rich wild-type (WT) plants. In-vitro feeding of sakuranetin suggested that this flavonoid directly inhibited the growth of YLS. BPH feeding on nomt lines accumulated higher cholesterol levels, which might be attributed to increases in the supply of sterol precursors from the YLS, while nomt lines suffered more damage than WT plants did from BPH herbivory. BPH-elicited accumulation of sakuranetin requires intact jasmonate (JA) signaling. This study reveals that rice uses a JA-induced antifungal flavonoid phytoalexin in defense against BPH by inhibiting its beneficial endosymbionts.
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Hemípteros , Oryza , Animais , Feminino , Antifúngicos , Flavonoides/farmacologia , Regulação da Expressão Gênica de Plantas , Oryza/genéticaRESUMO
BACKGROUNDS: In patients with liver failure, continuous renal replacement therapy (CRRT) without anticoagulation may be necessary. A new heparin coated membrane (oXiris®) may prolong circuit life in this setting. OBJECTIVES: In liver failure patients not receiving anticoagulation, to compare CRRT circuit life with the oXiris® versus the AN69 ST100 (usual care) membrane. METHODS: Randomized single cross-over trial. RESULTS: We studied 20 patients and 39 circuits. Twenty-five treatments used femoral and 14 internal jugular access catheters. Median circuit life was 21 h (IQR: 8.25-35.5) with the AN69 versus 16.0 h (14-25) with the oXiris® membrane (p = 0.36). Median first circuit duration was 14 (11.25-23) h for the AN69 ST100 versus 16 (8 -26) for the oXiris® membrane. There was also no difference between the AN69 ST100 or oXiris® membrane circuits using femoral access at 13 (8 -22.5) versus 15.5 (12.5-21.5) h (p = 0.57) or internal jugular access at 28 (13-47) versus 23 (21-29) h (p = 0.79), respectively. CONCLUSIONS: The oXiris® heparin-grafted membrane does not appear to prolong circuit life in liver failure patients receiving CRRT without anticoagulation.