Protein arginine methyltransferases(PRMTs) catalyze the methylation of a variety of protein substrates, many of which have been linked to the development, progression and aggressiveness of different types of cancer. M...Protein arginine methyltransferases(PRMTs) catalyze the methylation of a variety of protein substrates, many of which have been linked to the development, progression and aggressiveness of different types of cancer. Moreover, aberrant expression of PRMTs has been observed in several cancer types. While the link between PRMTs and cancer is a relatively new area of interest, the functional implications documented thus far warrant further investigations into its therapeutic potential. However, the expression of these enzymes and the regulation of their activity in cancer are still significantly understudied. Currently there are nine main members of the PRMT family. Further, the existence of alternatively spliced isoforms for several of these family members provides an additional layer of complexity. Specifically, PRMT1, PRMT2, CARM1 and PRMT7 have been shown to have alternative isoforms and others may be currently unrealized. Our knowledge with respect to the relative expression and the specific functions of these isoforms is largely lacking and needs attention. Here we present a review of the current knowledge of theknown alternative PRMT isoforms and provide a rationale for how they may impact on cancer and represent potentially useful targets for the development of novel therapeutic strategies.展开更多
To defend themselves against herbivore attack, plants produce secondary metabolites, which are variously inducible and constitutively deployed, presumably to optimize their fitness benefits in light of their fitness c...To defend themselves against herbivore attack, plants produce secondary metabolites, which are variously inducible and constitutively deployed, presumably to optimize their fitness benefits in light of their fitness costs. Three phytohormones, jasmonates （JA） and their active forms, the JA-isoleucine （JA-Ile） and ethylene （ET）, are known to play central roles in the elicitation of induced defenses, but little is known about how this mediation changes over ontogeny. The Optimal Defense Theory （ODT） predicts changes in the costs and benefits of the different types of defenses and has been usefully extrapolated to their modes of deployment. Here we studied whether the herbivore-induced accumulation of JA, JA-Ile and ET changed over ontogeny in Nicotiana attenuata, a native tobacco in which inducible defenses are particularly well studied. Herbivore-elicited ET production changed dramatically during six developmental stages, from rosette through flowering, decreasing with the elongation of the first corollas during flower development. This decrease was largely recovered within a day after flower removal by decapitation. A similar pattern was found for the herbivore-induced accumulation of JA and JA-Ile. These results are consistent with ODT predictions and suggest that the last steps in floral development control the inducibility of at least three plant hormones, optimizing defense-growth tradeoffs.展开更多
Nitric oxide-associated protein 1 （NOA1） is involved in various abiotic stress responses and is required for plant resistance to pathogen infections. However, the role of NOA1 in plant-herbivore interactions has not...Nitric oxide-associated protein 1 （NOA1） is involved in various abiotic stress responses and is required for plant resistance to pathogen infections. However, the role of NOA1 in plant-herbivore interactions has not been explored. We created NOA1-silenced Nicotiana attenuata plants （irNaNOA1）. Compared with wild-type （WT） plants, irNaNOA1 plants had highly decreased photosynthesis rates. We further examined various traits important for plant defense against its specialist herbivore Manduca sexta by treating WT and irNaNOA1 plants with mechanical wounding and M. sexta oral secretions （OS）. NOA1-silenced plants showed elevated levels of herbivory-induced jasmonic acid （JA）, but decreased JA-isoleucine conjugate （JA-Ile） levels. The decreased JA-Ile levels did not result from compromised JAR （jasmonic acid resistant） activity in irNOA1 plants. Moreover, nitrogen-rich defensive compounds, nicotine and trypsin proteinase inhibitors, did not differ between WT and irNaNOA1 plants. In contrast, concentrations of most carbon-based defensive compounds were lower in these plants than in WT plants, although the levels of chlorogenic acid were not changed. Therefore, silencing NOA1 alters the allocation of carbon resources within the phenylpropanoid pathway. These data suggest the involvement of NOA1 in N. attenuata’s defense against M. sexta attack, and highlight its role in photosynthesis, and biosynthesis of jasmonates and secondary metabolites.展开更多
Multiple robotic flexible endoscope platforms have been developed based on cross specialty collaboration between engineers and medical doctors. However, significant number of these platforms have been developed for th...Multiple robotic flexible endoscope platforms have been developed based on cross specialty collaboration between engineers and medical doctors. However, significant number of these platforms have been developed for the natural orifice transluminal endo-scopic surgery paradigm. Increasing amount of evidence suggest the focus of development should be placed on advanced endolumenal procedures such as endoscopic submucosal dissection instead. A thorough literature analysis was performed to assess the current status of robotic flexible endoscopic platforms designed for advanced endolumenal procedures. Current efforts are mainly focused on robotic locomotion and robotic instrument control. In the future, advances in actuation and servoing technology, optical analysis, augmented reality and wireless power transmission technology will no doubt further advance the field of robotic endoscopy. Globally, health systems have become increasingly budget conscious; widespread acceptance of robotic endoscopy will depend on careful design to ensure its delivery of a cost effective service.展开更多
Pancreatic cancer is one of the most aggressive and lethal malignancies worldwide, with a very poor prognosis and a five-year survival rate less than 8%. This dismal outcome is largely due to delayed diagnosis, early ...Pancreatic cancer is one of the most aggressive and lethal malignancies worldwide, with a very poor prognosis and a five-year survival rate less than 8%. This dismal outcome is largely due to delayed diagnosis, early distant dissemination and resistance to conventional chemotherapies. Kras mutation is a well-defined hallmark of pancreatic cancer, with over 95% of cases harbouring Kras mutations that give rise to constitutively active forms of Kras. As important down-stream effectors of Kras, p21-activated kinases(PAKs) are involved in regulating cell proliferation, apoptosis, invasion/migration and chemo-resistance. Immunotherapy is now emerging as a promising treatment modality in the era of personalized anti-cancer therapeutics. In this review, basic knowledge of PAK structure and regulation is briefly summarised and the pivotal role of PAKs in Kras-driven pancreatic cancer is highlighted in terms of tumour biology and chemoresistance. Finally, the involvement of PAKs in immune modulation in the tumour microenvironment is discussed and the potential advantages of targeting PAKs are explored.展开更多
Citrus greening disease or huanglongbing(HLB)is associated with excessive pre-harvest fruit drop.To understand the mechanisms of the HLB-associated fruit abscission,transcriptomes were analyzed by RNA sequencing of ca...Citrus greening disease or huanglongbing(HLB)is associated with excessive pre-harvest fruit drop.To understand the mechanisms of the HLB-associated fruit abscission,transcriptomes were analyzed by RNA sequencing of calyx abscission zones(AZ-C)of dropped“Hamlin”oranges from HLB-diseased trees upon shaking the trees(Dd),retained oranges on diseased trees(Rd),dropped oranges from healthy shaken trees(Dh),and retained oranges on healthy trees(Rh).Cluster analysis of transcripts indicated that Dd had the largest distances from all other groups.Comparisons of transcriptomes revealed 1047,1599,813,and 764 differentially expressed genes(DEGs)between Dd/Rd,Dd/Dh,Dh/Rh,and Rd/Rh.The gene ontology(GO)and Kyoto Encyclopedia of Genes and Genomes(KEGG)pathway enrichment analyses indicated hormone signaling,defense response,and secondary metabolism were involved in HLB-associated fruit abscission.Ethylene(ET)and jasmonic acid(JA)synthesis/signaling-related genes were upregulated in Dd,while other phytohormone-related genes were generally downregulated.In addition,genes related to JA/ET-activated defense response were upregulated in Dd as well.Consistent with the phytohormone gene expression data,increased levels(p<0.05)of ET and JA,and a decreased level(p<0.05)of abscisic acid were found in Dd compared with Rd,Dh or Rh.Lasiodiploidia theobromae level in Dd AZ-C was higher than the other fruit types,confirmed by qPCR,indicating AZ-C secondary fungal infection of HLB fruit may exacerbate their abscission.This information will help formulate effective strategies to control HLB-related abscission.展开更多
The peritrophic matrix （PM） is essential for insect digestive system physiol- ogy as it protects the midgut epithelium from damage by food particles, pathogens, and toxins. The PM is also an attractive target for de...The peritrophic matrix （PM） is essential for insect digestive system physiol- ogy as it protects the midgut epithelium from damage by food particles, pathogens, and toxins. The PM is also an attractive target for development of new pest control strategies due to its per os accessibility. To understand how the PM performs these functions, the molecular architecture of the PM was examined using genomic and proteomic approaches in Mamestra configurata （Lepidoptera： Noctuidae）, a major pest of cruciferous oilseed crops in North America. Liquid chromatography-tandem mass spectrometry analyses of the PM identified 82 proteins classified as： （i） peritrophins, including a new class with a CBDIII domain; （ii） enzymes involved in chitin modification （chitin deacetylases）, di- gestion （serine proteases, aminopeptidases, carboxypeptidases, lipases and ^-amylase） or other reactions （/^-l,3-glucanase, alkaline phosphatase, dsRNase, astacin, pantetheinase）; （iii） a heterogenous group consisting of polycalin, REPATs, serpin, C-Type lectin and Lsti99/Lsti201 and 3 novel proteins without known orthologs. The genes encoding PM proteins were expressed predominantly in the midgut, cDNAs encoding chitin synthase-2 （McCHS-2）, chitinase （McCHI）, and fl-N-acetylglucosaminidase （McNAG） enzymes, in- volved in PM chitin metabolism, were also identified. McCHS-2 expression was specific to the midgut indicating that it is responsible for chitin synthesis in the PM, the only chitinous material in the midgut. In contrast, the genes encoding the chitinolytic enzymes were expressed in multiple tissues. McCHS-2, McCHI, and McNAG were expressed in the midgut of feeding larvae, and NAG activity was present in the PM. This information was used to generate an updated model of the lepidopteran PM architecture.展开更多
Southeastern wildrye (Elymus glabriflorus, Vasey ex L.H. Dewey) is a cool-season, perennial grass native to southeastern United States. Recently, there is a growing interest in its development as a grazing and haying ...Southeastern wildrye (Elymus glabriflorus, Vasey ex L.H. Dewey) is a cool-season, perennial grass native to southeastern United States. Recently, there is a growing interest in its development as a grazing and haying forage crop due to its wide area of adaptation across this region. Consequently, there is a great need for the evaluation of its forage quality by rapid, but accurate analytical methods like Near-Infrared Reflectance Spectroscopy (NIRS). In this study, acceptable NIRS calibration models were developed for: dry matter, DM (n = 113, R<sup>2</sup> = 0.904, RSCD = 2.54, RSCIQ = 4.65);crude protein, CP (n = 113, R<sup>2</sup> = 0.974, RSCD = 5.16, RSCIQ = 5.92);acid detergent fiber, ADF (n = 116, R<sup>2</sup> = 0.896, RSCD = 2.35, RSCIQ = 1.28);neutral detergent fiber, NDF (n = 118, R<sup>2</sup> = 0.934, RSCD = 2.53, RSCIQ = 3.38);digestible dry matter, DDM (n = 116, R<sup>2</sup> = 0.895, RSCD = 2.36, RSCIQ = 1.35);dry matter intake, DMI (n = 115, R<sup>2</sup> = 0.924, RSCD = 2.40, RSCIQ = 2.53);and relative feed value, RFV (n = 114, R<sup>2</sup> = 0.932, RSCD = 2.94, RSCIQ = 2.81). Prediction of independent validation sets yielded good agreement between the NIRS predicted values and the laboratory reference values for each of: DM (n = 53, R<sup>2</sup> = 0.831, RPD = 2.45, RPIQ = 4.24);CP (n = 57, R<sup>2</sup> = 0.967, RPD = 5.37, RPIQ = 7.16);ADF (n = 49, R<sup>2</sup> = 0.895, RPD = 2.97, RPIQ = 1.51);NDF (n = 53, R<sup>2</sup> = 0.928, RPD = 3.75, RPIQ = 4.22);digestible dry matter, DDM (n = 55, R<sup>2</sup> = 0.860, RSCD = 265, RSCIQ = 1.15);dry matter intake, DMI (n = 156, R<sup>2</sup> = 0.845, RSCD = 2.48, RSCIQ = 2.11);and relative feed value, RFV (n = 55, R<sup>2</sup> = 0.916, RSCD = 3.45, RSCIQ = 3.04) contents, indicating that all seven calibration models had good quantitative information. Therefore, precise, accurate, and rapid analysis of these important forage quality attributes of southeastern wildrye can be routinely done using the developed NIRS calibration models.展开更多
Direct synthesis of layer-tunable and transfer-free graphene on technologically important substrates is highly valued for various electronics and device applications.State of the art in the field is currently a two-st...Direct synthesis of layer-tunable and transfer-free graphene on technologically important substrates is highly valued for various electronics and device applications.State of the art in the field is currently a two-step process:a high-quality graphene layer synthesis on metal substrate through chemical vapor deposition(CVD)followed by delicate layer transfer onto device-relevant substrates.Here,we report a novel synthesis approach combining ion implantation for a precise graphene layer control and dual-metal smart Janus substrate for a diffusion-limiting graphene formation to directly synthesize large area,high quality,and layer-tunable graphene films on arbitrary substrates without the post-synthesis layer transfer process.Carbon(C)ion implantation was performed on Cu-Ni film deposited on a variety of device-relevant substrates.A well-controlled number of layers of graphene,primarily monolayer and bilayer,is precisely controlled by the equivalent fluence of the implanted C-atoms(1 monolayer~4×10^(15)C-atoms/cm^(2)).Upon thermal annealing to promote Cu-Ni alloying,the pre-implanted C-atoms in the Ni layer are pushed toward the Ni/substrate interface by the top Cu layer due to the poor C-solubility in Cu.As a result,the expelled C-atoms precipitate into a graphene structure at the interface facilitated by the Cu-like alloy catalysis.After removing the alloyed Cu-like surface layer,the layer-tunable graphene on the desired substrate is directly realized.The layer-selectivity,high quality,and uniformity of the graphene films are not only confirmed with detailed characterizations using a suite of surface analysis techniques but more importantly are successfully demonstrated by the excellent properties and performance of several devices directly fabricated from these graphene films.Molecular dynamics(MD)simulations using the reactive force field(ReaxFF)were performed to elucidate the graphene formation mechanisms in this novel synthesis approach.With the wide use of ion implantation technology in the microelectronics展开更多
The midgut of most insects is lined with a semipermeable acellular tube, the peritrophic matrix （PM）, composed of chitin and proteins. Although various genes encoding PM proteins have been characterized, our underst...The midgut of most insects is lined with a semipermeable acellular tube, the peritrophic matrix （PM）, composed of chitin and proteins. Although various genes encoding PM proteins have been characterized, our understanding of their roles in PM structure and function is very limited. One promising approach for obtaining functional information is RNA interference, which has been used to reduce the levels of specific mRNAs using double-stranded RNAs administered to larvae by either injection or feeding. Although this method is well documented in dipterans and coleopterans, reports of its success in lepidopterans are varied. In the current study, the silencing midgut genes encoding PM proteins （insect intestinal mucin 1, insect intestinal mucin 4, PM protein 1） and the chitin biosynthetic or modifying enzymes （chitin synthase-B and chitin deacetylase 1） in a noctuid lepidopteran, Mamestra configurata, was examined in vitro and in vivo. In vitro studies in primary midgut epithelial cell preparations revealed an acute and rapid silencing （by 24 h） for the gene encoding chitin deacetylase 1 and a slower rate of silencing （by 72 h） for the gene encoding PM protein 1. Genes encoding insect intestinal mucins were slightly silenced by 72 h, whereas no silencing was detected for the gene encoding chitin synthase-B. In vivo experiments focused on chitin deacetylase 1, as the gene was silenced to the greatest extent in vitro. Continuous feeding of neonates and fourth instar larvae with double-stranded RNA resulted in silencing of chitin deacetylase 1 by 24 and 36 h, respectively. Feeding a single dose to neonates also resulted in silencing by 24 h. The current study demonstrates that genes encoding PM proteins can be silenced and outlines conditions for RNA interference by per os feeding in lepidopterans.展开更多
The superoxide （O^2-）-generating NADPH oxidases are crucial for the defense of plants against attack from pathogens; however, it remains unknown whether they also mediate responses against chewing insect herbivores....The superoxide （O^2-）-generating NADPH oxidases are crucial for the defense of plants against attack from pathogens; however, it remains unknown whether they also mediate responses against chewing insect herbivores. The transcripts of the respiratory burst NADPH oxidase homolog Narboh D in Nicotiana attenuate are rapidly and transiently elicited by wounding, and are amplified when Manduca sexta oral secretions （OS） are added to the wounds. The fatty-acid-amino-acid-conjugates （FACs）, demonstrably the major elicitors in M. sexta OS, are responsible for the increase in Narboh D transcripts. Silencing Narboh D significantly reduced reactive oxygen species （ROS） levels after OS elicitation, but neither OS-elicited jasmonic acid （JA） or JA-isoleucine （JA-Ile） bursts, pivotal hormones that regulates plant resistance to herbivores, nor early transcripts of herbivore defense-related genes （NaJAR4 and NaPAL1）, were influenced. However, late OS-elicited increases in trypsin proteinase inhibitors （TPIs）, as well as the transcript levels of defense genes such as polyphenol oxidase, TPI and Thionin were significantly reduced, in addition, Narboh D-silenced plants were more vulnerable to insect herbivores, especially the larvae of the generalist Spodoptera fittoralis. We thus conclude that Narboh D-based defenses play an important role in late herbivore-elicited responses.展开更多
Phytochromes mainly function in photoau- totrophic organisms to adjust growth in response to fluctuating light signals. The different isoforms of plant phytochromes often display both conserved and divergent roles, pr...Phytochromes mainly function in photoau- totrophic organisms to adjust growth in response to fluctuating light signals. The different isoforms of plant phytochromes often display both conserved and divergent roles, presumably to fine-tune plant responses to environmental signals and optimize fitness. Here we describe the distinct, yet partially redundant, roles of phytochromes NaPHYA, NaPHYB1 and NaPHYB2 in a wild tobacco species, Nicotiana attenuata using RNAi-silenced phytochrome lines. Consistent with results reported from other species, silencing the expression of NaPHYA or NaPHYB2 in N. attenuata had mild or no influence on plant develop- ment as long as NaPHYBI was functional; whereas silencing the expression of NaPHYB1 alone strongly altered flowering time and leaf morphology. Thecontribution of NaPHYB2 became significant only in the absence of NaPHYB1; plants silenced for both NaPHYB1 and NaPHYB2 largely skipped the rosette- stage of growth to rapidly produce long, slender stalks that bore flowers early： hallmarks of the shade- avoidance responses. The phenotyping of phyto- chrome-silenced lines, combined with sequence and transcript accumulation independent functional analysis, suggest the diversification of the phytochromes, and a dominant role of NaPHYB1 and NaPHYB2 in N. attenuata＇s vegetative and reproductive development.展开更多
DICER-like （DCL） proteins produce small RNAs that silence genes involved in development and defenses against viruses and pathogens. Which DCLs participate in plant-herbivore interactions remains unstudied. We identi...DICER-like （DCL） proteins produce small RNAs that silence genes involved in development and defenses against viruses and pathogens. Which DCLs participate in plant-herbivore interactions remains unstudied. We identified and stably silenced four distinct DCL genes by RNAi in Nicotiana attenuata （Torrey ex. Watson）, a model for the study of plant-herbivore interactions. Silencing DCL1 expression was lethal. Manduca sexta larvae performed significantly better on ir-dcl3 and ir-dcl4 plants, but not on ir-dcl2 plants compared to wild type plants. Phytohormones, defense metabolites and microarray analyses revealed that when DCL3 and DCL4 were silenced separately, herbivore resistance traits were regulated in distinctly different ways. Crossing of the lines revealed complex interactions in the patterns of regulation. Single ir-dcl4 and double ir-dcl2 ir-dcl3 plants were impaired in JA accumulation, while JA- Ile was increased in ir-dcl3 plants. Ir-dcl3 and ir-dcl4 plants were impaired in nicotine accumulation; silencing DCL2 in combination with either DCL3 or DCL4 restored nicotine levels to those of WT. Trypsin proteinase inhibitor activity and transcripts were only silenced in ir-dcl3 plants. We conclude that DCL2/3/4 interact in a complex manner to regulate anti-herbivore defenses and that these interactions significantly complicate the already challenging task of understanding smRNA function in the regulation of biotic interactions.展开更多
The brassinosteroid （BR） receptor, BR insensitive 1 （BRI1）, plays a critical role in plant development, but whether BRI1-mediated BR signaling is involved in plant defense responses to herbivores was largely unkno...The brassinosteroid （BR） receptor, BR insensitive 1 （BRI1）, plays a critical role in plant development, but whether BRI1-mediated BR signaling is involved in plant defense responses to herbivores was largely unknown. Here, we examined the function of BRI1 in the resistance of Nicotiana attenuata （Solanaceae） to its specialist insect herbivore Manduca sexta. Jasmonic acid （JA） and JA-isoleucine conjugate （JA-Ile） are important hormones that mediate resistance to herbivores and we found that after wounding or simulated herbivory NaBRI1 had little effect on JA levels, but was important for the induction of JA-Ile. Further experiments revealed that decreased JAR （the enzyme for JA-Ile production） activity and availability of Ile in NaBRI1-silenced plants were likely responsible for the low JA-Ile levels. Consistently, M. sexta larvae gained more weight on NaBRI1-silenced plants than on the control plants. Quantification of insect feeding-induced secondary metabolites revealed that silencing NaBRI1 resulted in decreased levels of carbon-rich defensive secondary metabolites （hydroxygeranyllinalool diterpene glycosides, chlorogenic acid, and rutin）, but had little effect on the nitrogen-rich ones （nicotine and trypsin proteinase inhibitors）. Thus, NaBRI1-mediated BR signaling is likely involved in plant defense responses to M. sexta, including maintaining JA-Ile levels and the accumulation of several carbon-rich defensive secondary metabolites.展开更多
The whole-plant activation of defense responses to wounding and herbivory requires systemic signaling in which jasmonates （JAs） play a pivotal role. To examine the nature of the slower cell-nonautonomous as compared...The whole-plant activation of defense responses to wounding and herbivory requires systemic signaling in which jasmonates （JAs） play a pivotal role. To examine the nature of the slower cell-nonautonomous as compared to the rapid cell-autonomous signal in mediating systemic defenses in Nicotiana attenuata, reciprocal stem graftingexperiments were used with plants silenced for the JA biosynthetic gene ALLENE OXIDE CYCLASE （irAOC） or plants transformed to create JA sinks by ectopicalIy expressing Arabidopsis JA-O-methyltransferase （ovJMT）. JA-impaired irAOC plants were defective in the cell-nonautonomous signaling pathway but not in JA transport. Conversely, ovJMT plants abrogated the production of a graft-transmissible JA signal. Both genotypes displayed unaltered cell-autonomous signaling. Defense responses （17-hydroxygeranyllinalool diterpene glycosides, nicotine, and proteinase inhibitors） and metabolite profiles were differently induced in irAOC and ovJMT scions in response to graft-transmissible signals from elicited wild type stocks. The performance of Manduca sexta larvae on the scions of different graft combinations was consistent with the patterns of systemic defense metabolite elicitations. Taken together, we conclude that JA and possibly MeJA, but not JA-lle, either directly functions as a long-distance transmissible signal or indirectly interacts with long distance signal（s） to activate systemic defense responses.展开更多
基金Supported by Cancer projects in the C télab are funded through the Cancer Research Society,Canadian Research Institutes of Health Research and Canadian Breast Cancer Foundation
文摘Protein arginine methyltransferases(PRMTs) catalyze the methylation of a variety of protein substrates, many of which have been linked to the development, progression and aggressiveness of different types of cancer. Moreover, aberrant expression of PRMTs has been observed in several cancer types. While the link between PRMTs and cancer is a relatively new area of interest, the functional implications documented thus far warrant further investigations into its therapeutic potential. However, the expression of these enzymes and the regulation of their activity in cancer are still significantly understudied. Currently there are nine main members of the PRMT family. Further, the existence of alternatively spliced isoforms for several of these family members provides an additional layer of complexity. Specifically, PRMT1, PRMT2, CARM1 and PRMT7 have been shown to have alternative isoforms and others may be currently unrealized. Our knowledge with respect to the relative expression and the specific functions of these isoforms is largely lacking and needs attention. Here we present a review of the current knowledge of theknown alternative PRMT isoforms and provide a rationale for how they may impact on cancer and represent potentially useful targets for the development of novel therapeutic strategies.
文摘To defend themselves against herbivore attack, plants produce secondary metabolites, which are variously inducible and constitutively deployed, presumably to optimize their fitness benefits in light of their fitness costs. Three phytohormones, jasmonates （JA） and their active forms, the JA-isoleucine （JA-Ile） and ethylene （ET）, are known to play central roles in the elicitation of induced defenses, but little is known about how this mediation changes over ontogeny. The Optimal Defense Theory （ODT） predicts changes in the costs and benefits of the different types of defenses and has been usefully extrapolated to their modes of deployment. Here we studied whether the herbivore-induced accumulation of JA, JA-Ile and ET changed over ontogeny in Nicotiana attenuata, a native tobacco in which inducible defenses are particularly well studied. Herbivore-elicited ET production changed dramatically during six developmental stages, from rosette through flowering, decreasing with the elongation of the first corollas during flower development. This decrease was largely recovered within a day after flower removal by decapitation. A similar pattern was found for the herbivore-induced accumulation of JA and JA-Ile. These results are consistent with ODT predictions and suggest that the last steps in floral development control the inducibility of at least three plant hormones, optimizing defense-growth tradeoffs.
文摘Nitric oxide-associated protein 1 （NOA1） is involved in various abiotic stress responses and is required for plant resistance to pathogen infections. However, the role of NOA1 in plant-herbivore interactions has not been explored. We created NOA1-silenced Nicotiana attenuata plants （irNaNOA1）. Compared with wild-type （WT） plants, irNaNOA1 plants had highly decreased photosynthesis rates. We further examined various traits important for plant defense against its specialist herbivore Manduca sexta by treating WT and irNaNOA1 plants with mechanical wounding and M. sexta oral secretions （OS）. NOA1-silenced plants showed elevated levels of herbivory-induced jasmonic acid （JA）, but decreased JA-isoleucine conjugate （JA-Ile） levels. The decreased JA-Ile levels did not result from compromised JAR （jasmonic acid resistant） activity in irNOA1 plants. Moreover, nitrogen-rich defensive compounds, nicotine and trypsin proteinase inhibitors, did not differ between WT and irNaNOA1 plants. In contrast, concentrations of most carbon-based defensive compounds were lower in these plants than in WT plants, although the levels of chlorogenic acid were not changed. Therefore, silencing NOA1 alters the allocation of carbon resources within the phenylpropanoid pathway. These data suggest the involvement of NOA1 in N. attenuata’s defense against M. sexta attack, and highlight its role in photosynthesis, and biosynthesis of jasmonates and secondary metabolites.
文摘Multiple robotic flexible endoscope platforms have been developed based on cross specialty collaboration between engineers and medical doctors. However, significant number of these platforms have been developed for the natural orifice transluminal endo-scopic surgery paradigm. Increasing amount of evidence suggest the focus of development should be placed on advanced endolumenal procedures such as endoscopic submucosal dissection instead. A thorough literature analysis was performed to assess the current status of robotic flexible endoscopic platforms designed for advanced endolumenal procedures. Current efforts are mainly focused on robotic locomotion and robotic instrument control. In the future, advances in actuation and servoing technology, optical analysis, augmented reality and wireless power transmission technology will no doubt further advance the field of robotic endoscopy. Globally, health systems have become increasingly budget conscious; widespread acceptance of robotic endoscopy will depend on careful design to ensure its delivery of a cost effective service.
基金Pancare Foundation (https://www.pancare.org.au) for supporting the pancreatic cancer research program in the Department of Surgery, University of Melbournesupported by Melbourne International Fee Remission Scholarship (MIFRS)+1 种基金Melbourne International Research Scholarship (MIRS)the Moshe Sambor Scholarship (Pancare Foundation)
文摘Pancreatic cancer is one of the most aggressive and lethal malignancies worldwide, with a very poor prognosis and a five-year survival rate less than 8%. This dismal outcome is largely due to delayed diagnosis, early distant dissemination and resistance to conventional chemotherapies. Kras mutation is a well-defined hallmark of pancreatic cancer, with over 95% of cases harbouring Kras mutations that give rise to constitutively active forms of Kras. As important down-stream effectors of Kras, p21-activated kinases(PAKs) are involved in regulating cell proliferation, apoptosis, invasion/migration and chemo-resistance. Immunotherapy is now emerging as a promising treatment modality in the era of personalized anti-cancer therapeutics. In this review, basic knowledge of PAK structure and regulation is briefly summarised and the pivotal role of PAKs in Kras-driven pancreatic cancer is highlighted in terms of tumour biology and chemoresistance. Finally, the involvement of PAKs in immune modulation in the tumour microenvironment is discussed and the potential advantages of targeting PAKs are explored.
基金supported by Southern Gardens Citrus Nursery LLC,a subsidiary company of US Sugar Corporation.
文摘Citrus greening disease or huanglongbing(HLB)is associated with excessive pre-harvest fruit drop.To understand the mechanisms of the HLB-associated fruit abscission,transcriptomes were analyzed by RNA sequencing of calyx abscission zones(AZ-C)of dropped“Hamlin”oranges from HLB-diseased trees upon shaking the trees(Dd),retained oranges on diseased trees(Rd),dropped oranges from healthy shaken trees(Dh),and retained oranges on healthy trees(Rh).Cluster analysis of transcripts indicated that Dd had the largest distances from all other groups.Comparisons of transcriptomes revealed 1047,1599,813,and 764 differentially expressed genes(DEGs)between Dd/Rd,Dd/Dh,Dh/Rh,and Rd/Rh.The gene ontology(GO)and Kyoto Encyclopedia of Genes and Genomes(KEGG)pathway enrichment analyses indicated hormone signaling,defense response,and secondary metabolism were involved in HLB-associated fruit abscission.Ethylene(ET)and jasmonic acid(JA)synthesis/signaling-related genes were upregulated in Dd,while other phytohormone-related genes were generally downregulated.In addition,genes related to JA/ET-activated defense response were upregulated in Dd as well.Consistent with the phytohormone gene expression data,increased levels(p<0.05)of ET and JA,and a decreased level(p<0.05)of abscisic acid were found in Dd compared with Rd,Dh or Rh.Lasiodiploidia theobromae level in Dd AZ-C was higher than the other fruit types,confirmed by qPCR,indicating AZ-C secondary fungal infection of HLB fruit may exacerbate their abscission.This information will help formulate effective strategies to control HLB-related abscission.
文摘The peritrophic matrix （PM） is essential for insect digestive system physiol- ogy as it protects the midgut epithelium from damage by food particles, pathogens, and toxins. The PM is also an attractive target for development of new pest control strategies due to its per os accessibility. To understand how the PM performs these functions, the molecular architecture of the PM was examined using genomic and proteomic approaches in Mamestra configurata （Lepidoptera： Noctuidae）, a major pest of cruciferous oilseed crops in North America. Liquid chromatography-tandem mass spectrometry analyses of the PM identified 82 proteins classified as： （i） peritrophins, including a new class with a CBDIII domain; （ii） enzymes involved in chitin modification （chitin deacetylases）, di- gestion （serine proteases, aminopeptidases, carboxypeptidases, lipases and ^-amylase） or other reactions （/^-l,3-glucanase, alkaline phosphatase, dsRNase, astacin, pantetheinase）; （iii） a heterogenous group consisting of polycalin, REPATs, serpin, C-Type lectin and Lsti99/Lsti201 and 3 novel proteins without known orthologs. The genes encoding PM proteins were expressed predominantly in the midgut, cDNAs encoding chitin synthase-2 （McCHS-2）, chitinase （McCHI）, and fl-N-acetylglucosaminidase （McNAG） enzymes, in- volved in PM chitin metabolism, were also identified. McCHS-2 expression was specific to the midgut indicating that it is responsible for chitin synthesis in the PM, the only chitinous material in the midgut. In contrast, the genes encoding the chitinolytic enzymes were expressed in multiple tissues. McCHS-2, McCHI, and McNAG were expressed in the midgut of feeding larvae, and NAG activity was present in the PM. This information was used to generate an updated model of the lepidopteran PM architecture.
基金supported by the National Key R&D Program of China(No.2022YFA1203400)the National Natural Science Foundation of China under Grant(Nos.62174093 and 12075307)+7 种基金the Ningbo Youth Science and Technology Innovation Leading Talent Project under Grant(No.2023QL006)the Open Research Fund of China National Key Laboratory of Materials for Integrated Circuits(No.NKLJC-K2023-01)Guangdong Basic and Applied Basic Research Foundation(No.2022A1515110628)the support by LDRD Seedling ER project at Los Alamos National Laboratory,NM,USA(No.20210867ER)partially supported by Guangdong Provincial Key Laboratory of Computational Science and Material Design(No.2019B030301001)supported by Center for Computational Science and Engineering at Southern University of Science and TechnologyShanghai Rising-Star Program(No.21QA1410900)the support from the Youth Innovation Promotion Association CAS
文摘Direct synthesis of layer-tunable and transfer-free graphene on technologically important substrates is highly valued for various electronics and device applications.State of the art in the field is currently a two-step process:a high-quality graphene layer synthesis on metal substrate through chemical vapor deposition(CVD)followed by delicate layer transfer onto device-relevant substrates.Here,we report a novel synthesis approach combining ion implantation for a precise graphene layer control and dual-metal smart Janus substrate for a diffusion-limiting graphene formation to directly synthesize large area,high quality,and layer-tunable graphene films on arbitrary substrates without the post-synthesis layer transfer process.Carbon(C)ion implantation was performed on Cu-Ni film deposited on a variety of device-relevant substrates.A well-controlled number of layers of graphene,primarily monolayer and bilayer,is precisely controlled by the equivalent fluence of the implanted C-atoms(1 monolayer~4×10^(15)C-atoms/cm^(2)).Upon thermal annealing to promote Cu-Ni alloying,the pre-implanted C-atoms in the Ni layer are pushed toward the Ni/substrate interface by the top Cu layer due to the poor C-solubility in Cu.As a result,the expelled C-atoms precipitate into a graphene structure at the interface facilitated by the Cu-like alloy catalysis.After removing the alloyed Cu-like surface layer,the layer-tunable graphene on the desired substrate is directly realized.The layer-selectivity,high quality,and uniformity of the graphene films are not only confirmed with detailed characterizations using a suite of surface analysis techniques but more importantly are successfully demonstrated by the excellent properties and performance of several devices directly fabricated from these graphene films.Molecular dynamics(MD)simulations using the reactive force field(ReaxFF)were performed to elucidate the graphene formation mechanisms in this novel synthesis approach.With the wide use of ion implantation technology in the microelectronics
文摘The midgut of most insects is lined with a semipermeable acellular tube, the peritrophic matrix （PM）, composed of chitin and proteins. Although various genes encoding PM proteins have been characterized, our understanding of their roles in PM structure and function is very limited. One promising approach for obtaining functional information is RNA interference, which has been used to reduce the levels of specific mRNAs using double-stranded RNAs administered to larvae by either injection or feeding. Although this method is well documented in dipterans and coleopterans, reports of its success in lepidopterans are varied. In the current study, the silencing midgut genes encoding PM proteins （insect intestinal mucin 1, insect intestinal mucin 4, PM protein 1） and the chitin biosynthetic or modifying enzymes （chitin synthase-B and chitin deacetylase 1） in a noctuid lepidopteran, Mamestra configurata, was examined in vitro and in vivo. In vitro studies in primary midgut epithelial cell preparations revealed an acute and rapid silencing （by 24 h） for the gene encoding chitin deacetylase 1 and a slower rate of silencing （by 72 h） for the gene encoding PM protein 1. Genes encoding insect intestinal mucins were slightly silenced by 72 h, whereas no silencing was detected for the gene encoding chitin synthase-B. In vivo experiments focused on chitin deacetylase 1, as the gene was silenced to the greatest extent in vitro. Continuous feeding of neonates and fourth instar larvae with double-stranded RNA resulted in silencing of chitin deacetylase 1 by 24 and 36 h, respectively. Feeding a single dose to neonates also resulted in silencing by 24 h. The current study demonstrates that genes encoding PM proteins can be silenced and outlines conditions for RNA interference by per os feeding in lepidopterans.
文摘The superoxide （O^2-）-generating NADPH oxidases are crucial for the defense of plants against attack from pathogens; however, it remains unknown whether they also mediate responses against chewing insect herbivores. The transcripts of the respiratory burst NADPH oxidase homolog Narboh D in Nicotiana attenuate are rapidly and transiently elicited by wounding, and are amplified when Manduca sexta oral secretions （OS） are added to the wounds. The fatty-acid-amino-acid-conjugates （FACs）, demonstrably the major elicitors in M. sexta OS, are responsible for the increase in Narboh D transcripts. Silencing Narboh D significantly reduced reactive oxygen species （ROS） levels after OS elicitation, but neither OS-elicited jasmonic acid （JA） or JA-isoleucine （JA-Ile） bursts, pivotal hormones that regulates plant resistance to herbivores, nor early transcripts of herbivore defense-related genes （NaJAR4 and NaPAL1）, were influenced. However, late OS-elicited increases in trypsin proteinase inhibitors （TPIs）, as well as the transcript levels of defense genes such as polyphenol oxidase, TPI and Thionin were significantly reduced, in addition, Narboh D-silenced plants were more vulnerable to insect herbivores, especially the larvae of the generalist Spodoptera fittoralis. We thus conclude that Narboh D-based defenses play an important role in late herbivore-elicited responses.
基金supported by European Research Council advanced grant Clockwork Green (293926) to ITBthe Global Research Lab program (2012055546) from the National Research Foundation of Korea+2 种基金Institute for Basic Science (IBS-R021-D1)Human Frontier Science Program (RGP0002/2012)the Max Planck Society
文摘Phytochromes mainly function in photoau- totrophic organisms to adjust growth in response to fluctuating light signals. The different isoforms of plant phytochromes often display both conserved and divergent roles, presumably to fine-tune plant responses to environmental signals and optimize fitness. Here we describe the distinct, yet partially redundant, roles of phytochromes NaPHYA, NaPHYB1 and NaPHYB2 in a wild tobacco species, Nicotiana attenuata using RNAi-silenced phytochrome lines. Consistent with results reported from other species, silencing the expression of NaPHYA or NaPHYB2 in N. attenuata had mild or no influence on plant develop- ment as long as NaPHYBI was functional; whereas silencing the expression of NaPHYB1 alone strongly altered flowering time and leaf morphology. Thecontribution of NaPHYB2 became significant only in the absence of NaPHYB1; plants silenced for both NaPHYB1 and NaPHYB2 largely skipped the rosette- stage of growth to rapidly produce long, slender stalks that bore flowers early： hallmarks of the shade- avoidance responses. The phenotyping of phyto- chrome-silenced lines, combined with sequence and transcript accumulation independent functional analysis, suggest the diversification of the phytochromes, and a dominant role of NaPHYB1 and NaPHYB2 in N. attenuata＇s vegetative and reproductive development.
基金the Max Planck Society for fundingSPP acknowledges support from MPG-DST India partner program
文摘DICER-like （DCL） proteins produce small RNAs that silence genes involved in development and defenses against viruses and pathogens. Which DCLs participate in plant-herbivore interactions remains unstudied. We identified and stably silenced four distinct DCL genes by RNAi in Nicotiana attenuata （Torrey ex. Watson）, a model for the study of plant-herbivore interactions. Silencing DCL1 expression was lethal. Manduca sexta larvae performed significantly better on ir-dcl3 and ir-dcl4 plants, but not on ir-dcl2 plants compared to wild type plants. Phytohormones, defense metabolites and microarray analyses revealed that when DCL3 and DCL4 were silenced separately, herbivore resistance traits were regulated in distinctly different ways. Crossing of the lines revealed complex interactions in the patterns of regulation. Single ir-dcl4 and double ir-dcl2 ir-dcl3 plants were impaired in JA accumulation, while JA- Ile was increased in ir-dcl3 plants. Ir-dcl3 and ir-dcl4 plants were impaired in nicotine accumulation; silencing DCL2 in combination with either DCL3 or DCL4 restored nicotine levels to those of WT. Trypsin proteinase inhibitor activity and transcripts were only silenced in ir-dcl3 plants. We conclude that DCL2/3/4 interact in a complex manner to regulate anti-herbivore defenses and that these interactions significantly complicate the already challenging task of understanding smRNA function in the regulation of biotic interactions.
文摘The brassinosteroid （BR） receptor, BR insensitive 1 （BRI1）, plays a critical role in plant development, but whether BRI1-mediated BR signaling is involved in plant defense responses to herbivores was largely unknown. Here, we examined the function of BRI1 in the resistance of Nicotiana attenuata （Solanaceae） to its specialist insect herbivore Manduca sexta. Jasmonic acid （JA） and JA-isoleucine conjugate （JA-Ile） are important hormones that mediate resistance to herbivores and we found that after wounding or simulated herbivory NaBRI1 had little effect on JA levels, but was important for the induction of JA-Ile. Further experiments revealed that decreased JAR （the enzyme for JA-Ile production） activity and availability of Ile in NaBRI1-silenced plants were likely responsible for the low JA-Ile levels. Consistently, M. sexta larvae gained more weight on NaBRI1-silenced plants than on the control plants. Quantification of insect feeding-induced secondary metabolites revealed that silencing NaBRI1 resulted in decreased levels of carbon-rich defensive secondary metabolites （hydroxygeranyllinalool diterpene glycosides, chlorogenic acid, and rutin）, but had little effect on the nitrogen-rich ones （nicotine and trypsin proteinase inhibitors）. Thus, NaBRI1-mediated BR signaling is likely involved in plant defense responses to M. sexta, including maintaining JA-Ile levels and the accumulation of several carbon-rich defensive secondary metabolites.
基金the Max-Planck-Society,the Advanced Grant No 293926 of the European Research Council to ITBDFG-funded Collaborative Research Centre “Chemical Mediators in Complex Biosystems-Chem Bio Sys”(SFB 1127) for funding
文摘The whole-plant activation of defense responses to wounding and herbivory requires systemic signaling in which jasmonates （JAs） play a pivotal role. To examine the nature of the slower cell-nonautonomous as compared to the rapid cell-autonomous signal in mediating systemic defenses in Nicotiana attenuata, reciprocal stem graftingexperiments were used with plants silenced for the JA biosynthetic gene ALLENE OXIDE CYCLASE （irAOC） or plants transformed to create JA sinks by ectopicalIy expressing Arabidopsis JA-O-methyltransferase （ovJMT）. JA-impaired irAOC plants were defective in the cell-nonautonomous signaling pathway but not in JA transport. Conversely, ovJMT plants abrogated the production of a graft-transmissible JA signal. Both genotypes displayed unaltered cell-autonomous signaling. Defense responses （17-hydroxygeranyllinalool diterpene glycosides, nicotine, and proteinase inhibitors） and metabolite profiles were differently induced in irAOC and ovJMT scions in response to graft-transmissible signals from elicited wild type stocks. The performance of Manduca sexta larvae on the scions of different graft combinations was consistent with the patterns of systemic defense metabolite elicitations. Taken together, we conclude that JA and possibly MeJA, but not JA-lle, either directly functions as a long-distance transmissible signal or indirectly interacts with long distance signal（s） to activate systemic defense responses.
