Wireworm in Quebec Field Crops: Specific Community Composition in North America.

Wireworms are important economic pests that attack the seeds and roots of numerous vegetable and field crops worldwide. A 5-yr study was conducted in the main agricultural regions of the province of Quebec (Canada), to identify and characterize the wireworm communities (Coleoptera: Elateridae) that occur in fields planted with economically important crops (maize, soybean, cereals, canola, and grasslands). Bait traps were used to collect wireworms each spring from 2011 to 2015. More than 600 sites were sampled in total, involving ca. 14,000 traps. Wireworms were found in 69% of the sites and 73% of the traps. A total of 6,014 wireworms were collected and identified to genus, or to species when possible. The results show that nine genera occur in Quebec and that Hypnoidus abbreviatus (Say) is currently the most abundant species in arable land in Quebec, representing 72% of all collected wireworms. The other genera collected were Melanotus (8% of all wireworms collected), Ampedus (7%), Limonius (6%), and Agriotes (4%). Wireworms from the genera Aeolus, Dalopius, Hemicrepidius, and Oestodes constituted ca. 3% together. The predominance of H. abbreviatus appeared to be specific to Quebec compared with the other Canadian provinces and the rest of North America. We observed differences in the relative abundance of wireworm genera among the agricultural regions sampled. However, no effect of current and preceding crops was observed in this study. Our results suggest that integrated pest management strategies for managing wireworms in Quebec fields should take into consideration the species present in each agronomical region.

Sub-nanosecond Yb:KLu(WO4)2 microchip laser.

A diode-pumped Yb:KLu(WO4)2 microchip laser passively Q-switched by a Cr4+:YAG saturable absorber generated a maximum average output power of 590 mW at 1031 nm with a slope efficiency of 55%. The pulse characteristics were 690 ps/47.6 µJ at a pulse repetition frequency of 12.4 kHz. The output beam had an excellent circular profile with M2<1.05. Yb:KLu(WO4)2 is very promising for ultrathin sub-ns microchip lasers.

Passive Q-switching of a Tm,Ho:KLu(WO4)2 microchip laser by a Cr:ZnS saturable absorber.

A diode-pumped Tm,Ho:KLu(WO4)2 microchip laser passively Q-switched with a Cr:ZnS saturable absorber generated an average output power of 131 mW at 2063.6 nm with a slope efficiency of 11% and a Q-switching conversion efficiency of 58%. The pulse characteristics were 14 ns/9 µJ at a pulse repetition frequency of 14.5 kHz. With higher modulation depth of the saturable absorber, 9 ns/10.4 µJ/8.2 kHz pulses were generated at 2061.1 nm, corresponding to a record peak power extracted from a passively Q-switched Tm,Ho laser of 1.15 kW. A theoretical model is presented, predicting the pulse energy and duration. The simulations are in good agreement with the experimental results.

Flooding tolerance: O2 sensing and survival strategies.

The investigation of flooding survival strategies in model, crop and wild plant species has yielded insights into molecular, physiological and developmental mechanisms of soil flooding (waterlogging) and submergence survival. The antithetical flooding escape and quiescence strategies of deepwater and submergence tolerant rice (Oryza sativa), respectively, are regulated by members of a clade of ethylene responsive factor transcriptional activators. This knowledge paved the way for the discovery that these proteins are targets of a highly conserved O2-sensing protein turnover mechanism in Arabidopsis thaliana. Further examples of genes that regulate transcription, root and shoot metabolism or development during floods have emerged. With the rapid advancement of genomic technologies, the mining of natural genetic variation in flooding tolerant wild species may ultimately benefit crop production.

Microgenomics: genome-scale, cell-specific monitoring of multiple gene regulation tiers.

The expression of nuclear protein-coding genes is controlled by dynamic mechanisms ranging from DNA methylation, chromatin modification, and gene transcription to mRNA maturation, turnover, and translation and the posttranslational control of protein function. A genome-scale assessment of the spatiotemporal regulation of gene expression is essential for a comprehensive understanding of gene regulatory networks. However, there are major obstacles to the precise evaluation of gene regulation in multicellular plant organs; these include the monitoring of regulatory processes at levels other than steady-state transcript abundance, resolution of gene regulation in individual cells or cell types, and effective assessment of transient gene activity manifested during development or in response to external cues. This review surveys the advantages and applications of microgenomics technologies that enable panoramic quantitation of cell-type-specific expression in plants, focusing on the importance of querying gene activity at multiple steps in the continuum, from histone modification to selective translation.

Natural variation of submergence tolerance among Arabidopsis thaliana accessions.

• The exploitation of natural variation in Arabidopsis thaliana (Arabidopsis) provides a huge potential for the identification of the molecular mechanisms underlying this variation as a result of the availability of a vast array of genetic and genomic resources for this species. Eighty-six Arabidopsis accessions were screened for natural variation in flooding tolerance. This forms the first step towards the identification and characterization of the role of candidate genes contributing to flooding tolerance. • Arabidopsis accessions at the 10-leaf stage were subjected to complete submergence in the dark. Survival curves were plotted to estimate median lethal times as a measure of tolerance. Flooding-associated survival parameters, such as root and shoot oxygen content, initial carbohydrate content and petiole elongation under water, were also measured. • There was a significant variation in submergence tolerance among Arabidopsis accessions. However, the order of tolerance did not correlate with root and shoot oxygen content or initial amounts of shoot starch and total soluble sugars. A negative correlation was observed between submergence tolerance and underwater petiole elongation. • Arabidopsis accessions show considerable variation in the ability to tolerate complete submergence, making it a good species in which to identify and characterize genes and to study mechanisms that contribute to survival under water.

Modelling honeybee visual guidance in a 3-D environment.

In view of the behavioral findings published on bees during the last two decades, it was proposed to decipher the principles underlying bees' autopilot system, focusing in particular on these insects' use of the optic flow (OF). Based on computer-simulated experiments, we developed a vision-based autopilot that enables a "simulated bee" to travel along a tunnel, controlling both its speed and its clearance from the right wall, left wall, ground, and roof. The flying agent thus equipped enjoys three translational degrees of freedom on the surge (x), sway (y), and heave (z) axes, which are uncoupled. This visuo-motor control system, which is called ALIS (AutopiLot using an Insect based vision System), is a dual OF regulator consisting of two interdependent feedback loops, each of which has its own OF set-point. The experiments presented here showed that the simulated bee was able to navigate safely along a straight or tapered tunnel and to react appropriately to any untoward OF perturbations, such as those resulting from the occasional lack of texture on one wall or the tapering of the tunnel. The minimalistic visual system used here (involving only eight pixels) suffices to jointly control both the clearance from the four walls and the forward speed, without having to measure any speeds or distances. The OF sensors and the simple visuo-motor control system we have developed account well for the results of ethological studies performed on honeybees flying freely along straight and tapered corridors.

Characterisation of a pneumatic muscle test station with two dynamic plants in cascade.

Pneumatic muscle actuators (PMAs) offer significant advantages over more traditional actuators, which make them prime candidates in rehabilitation devices. A dynamic test station (DTS) is modified to demonstrate the use of a PMA for this application. The DTS includes two dynamic systems: a PMA and a DC servomotor. An overall transfer function was developed utilising characterisation data for the PMA and DC servomotor. A Tustin (bilinear) transform was performed on the overall transfer function to obtain a discrete time system. Model parameters were optimised and used to generate input voltage profiles that achieve isokinetic (constant velocity) task specifications. Percent root mean square error values (PRMSE) between the actual and ideal profiles were used to evaluate the accuracy of this method in achieving isokinetic displacement. For PMA pressures (in kPa) of 150, 350 and 550 PRMSE were 7.80, 5.40 and 2.76, respectively.

Characterisation of a phenomenological model for commercial pneumatic muscle actuators.

This study focuses on the parameter characterisation of a three-element phenomenological model for commercially available pneumatic muscle actuators (PMAs). This model consists of a spring, damping and contractile element arranged in parallel. Data collected from static loading, contraction and relaxation experiments were fitted to theoretical solutions of the governing equation for the three-element model resulting in prediction profiles for the spring, damping and contractile force coefficient. For the spring coefficient, K N/mm, the following relationships were found: K = 32.7 - 0.0321P for 150 < or = P < or = 314 kPa and K = 17 + 0.0179P for 314 < or = P < or = 550 kPa. For the damping coefficient, B Ns/mm, the following relationship was found during contraction: B = 2.90 for 150 < or = P < or = 550 kPa. During relaxation, B = 1.57 for 150 < or = P < or = 372 kPa and B = 0.311 + 0.00338P for 372 < or = P < or = 550. The following relationship for the contractile force coefficient, F(ce) N, was also determined: F(ce) = 2.91P+44.6 for 150 < or = P < or = 550 kPa. The model was then validated by reasonably predicting the response of the PMA to a triangular wave input in pressure under a constant load on a dynamic test station.

Getting the message across: cytoplasmic ribonucleoprotein complexes.

mRNA-ribonucleoprotein (mRNP) complexes mediate post-transcriptional control mechanisms in the cell nucleus and cytoplasm. Transcriptional control is paramount to gene expression but is followed by regulated nuclear pre-mRNA maturation and quality control processes that culminate in the export of a functional transcript to the cytoplasm. Once in the cytosol, mRNPs determine the activity of individual mRNAs through regulation of localization, translation, sequestration and turnover. Here, we review how quantitative assessment of mRNAs in distinct cytoplasmic mRNPs, such as polyribosomes (polysomes), has provided new perspectives on post-transcriptional regulation from the global to gene-specific level. In addition, we explore recent genetic and biochemical studies of cytoplasmic mRNPs that have begun to expose RNA-binding proteins in an integrated network that fine-tunes gene expression.

Flooding stress: acclimations and genetic diversity.

Flooding is an environmental stress for many natural and man-made ecosystems worldwide. Genetic diversity in the plant response to flooding includes alterations in architecture, metabolism, and elongation growth associated with a low O(2) escape strategy and an antithetical quiescence scheme that allows endurance of prolonged submergence. Flooding is frequently accompanied with a reduction of cellular O(2) content that is particularly severe when photosynthesis is limited or absent. This necessitates the production of ATP and regeneration of NAD(+) through anaerobic respiration. The examination of gene regulation and function in model systems provides insight into low-O(2)-sensing mechanisms and metabolic adjustments associated with controlled use of carbohydrate and ATP. At the developmental level, plants can escape the low-O(2) stress caused by flooding through multifaceted alterations in cellular and organ structure that promote access to and diffusion of O(2). These processes are driven by phytohormones, including ethylene, gibberellin, and abscisic acid. This exploration of natural variation in strategies that improve O(2) and carbohydrate status during flooding provides valuable resources for the improvement of crop endurance of an environmental adversity that is enhanced by global warming.

The organization of cytoplasmic ribosomal protein genes in the Arabidopsis genome.

Eukaryotic ribosomes are made of two components, four ribosomal RNAs, and approximately 80 ribosomal proteins (r-proteins). The exact number of r-proteins and r-protein genes in higher plants is not known. The strong conservation in eukaryotic r-protein primary sequence allowed us to use the well-characterized rat (Rattus norvegicus) r-protein set to identify orthologues on the five haploid chromosomes of Arabidopsis. By use of the numerous expressed sequence tag (EST) accessions and the complete genomic sequence of this species, we identified 249 genes (including some pseudogenes) corresponding to 80 (32 small subunit and 48 large subunit) cytoplasmic r-protein types. None of the r-protein genes are single copy and most are encoded by three or four expressed genes, indicative of the internal duplication of the Arabidopsis genome. The r-proteins are distributed throughout the genome. Inspection of genes in the vicinity of r-protein gene family members confirms extensive duplications of large chromosome fragments and sheds light on the evolutionary history of the Arabidopsis genome. Examination of large duplicated regions indicated that a significant fraction of the r-protein genes have been either lost from one of the duplicated fragments or inserted after the initial duplication event. Only 52 r-protein genes lack a matching EST accession, and 19 of these contain incomplete open reading frames, confirming that most genes are expressed. Assessment of cognate EST numbers suggests that r-protein gene family members are differentially expressed.

Economic evaluation of a new acellular vaccine for pertussis in Canada.

OBJECTIVE: Pertussis is a highly contagious infection affecting mainly children. Acellular pertussis vaccines were recently introduced in Canada based on evidence of improved safety and efficacy over whole cell vaccines, the current standard of care. The following study reports the economic impact of replacing the whole cell vaccine (wP) by a new acellular vaccine (aP) in the Ontario pertussis immunisation programme. DESIGN: For a hypothetical cohort of 100,000 children from birth to the age of 8 years, the costs and consequences of pertussis vaccination with either aP or wP were compared. A decision analytical model was constructed for vaccine delivery, treatment of pertussis cases and vaccine adverse events, with analyses from the viewpoints of the Ontario Ministry of Health and society. MAIN OUTCOME MEASURES AND RESULTS: The main outcomes were expected number of pertussis cases, hospitalisations, and workdays lost by parents. Data on vaccine effectiveness, pertussis incidence, and other parameters used in the model were from published literature. Costs were discounted at 5%, and extensive sensitivity analyses were undertaken. Over 8 years, in a cohort of 100,000 children, the introduction of aP would prevent 10,500 cases of pertussis, avoiding 504 hospital admissions and 73,500 days of work absence. For Ontario, healthcare cost savings over the same period would amount to 275,585 Canadian dollars ($Can), and societal savings to $Can9,752,864

Regulated heterogeneity in 12-kDa P-protein phosphorylation and composition of ribosomes in maize (Zea mays L.).

Maize (Zea mays L.) possesses four distinct approximately 12-kDa P-proteins (P1, P2a, P2b, P3) that form the tip of a lateral stalk on the 60 S ribosomal subunit. RNA blot analyses suggested that the expression of these proteins was developmentally regulated. Western blot analysis of ribosomal proteins isolated from various organs, kernel tissues during seed development, and root tips deprived of oxygen (anoxia) revealed significant heterogeneity in the levels of these proteins. P1 and P3 were detected in ribosomes of all samples at similar levels relative to ribosomal protein S6, whereas P2a and P2b levels showed considerable developmental regulation. Both forms of P2 were present in ribosomes of some organs, whereas only one form was detected in other organs. Considerable tissue-specific variation was observed in levels of monomeric and multimeric forms of P2a. P2b was not detected in root tips, accumulated late in seed embryo and endosperm development, and was detected in soluble ribosomes but not in membrane-associated ribosomes that copurified with zein protein bodies of the kernel endosperm. The phosphorylation of the 12-kDa P-proteins was also developmentally and environmentally regulated. The potential role of P2 heterogeneity in P-protein composition in the regulation of translation is discussed.

Oxygen deprivation stimulates Ca2+-mediated phosphorylation of mRNA cap-binding protein eIF4E in maize roots.

Flooding of maize seedlings causes O2 deprivation that leads to a global reduction in protein synthesis and selective translation of cytoplasmic mRNAs. Since selective translation in animal cells can involve the cap-binding protein eIF4E, we characterized the distinct mRNA cap-binding proteins eIF4E and eIFiso4E of maize. These proteins have 45% deduced amino acid sequence identity and are highly conserved at residues of eIF4E that function in intermolecular interactions in animals. Maize eIF4E is a phosphoprotein. O2 deprivation resulted in a decrease in the isoelectric point of eIF4E, consistent with additional phosphorylation. Modification of eIF4E was mimicked by treatment with caffeine under aerobic conditions and blocked by treatment with ruthenium red under O2 deprivation, implicating Ca2+ as a second messenger in eIF4E modification. In contrast, no isoelectric variants of eIFiso4E were detected. The possible role of cytosolic Ca2+ and pH in regulation of mRNA cap-binding protein activity under O2 deprivation is discussed.

Characterization of the Arabidopsis lecRK-a genes: members of a superfamily encoding putative receptors with an extracellular domain homologous to legume lectins.

An Arabidopsis cDNA clone that defines a new class of plant serine/threonine receptor kinases was found to be a member of a family of four clustered genes (lecRK-a1-a4) which have been cloned, sequenced and mapped on chromosome 3. This family belongs to a large superfamily encoding putative receptors with an extracellular domain homologous to legume lectins and appears to be conserved at least among dicots. In the Columbia ecotype only the lecRK-a1 and perhaps the lecRK-a3 gene is functional, since lecRK-a2 is disrupted by a Ty-copia retroelement and lecRK-a4 contains a frameshift mutation. Structural analysis of the lecRK-al and lecRK-a3 deduced amino-acid sequences suggests that the lectin domain is unlikely to be involved in binding monosaccharides but could interact with complex glycans and/or with hydrophobic ligands. Immunodetection of lecRK gene products in plasma membranes purified by free-flow electrophoresis showed that the lecRK-a proteins are probably highly glycosylated integral plasma membrane components.

Selective translation of cytoplasmic mRNAs in plants.

Translation of mRNA is emerging as an important mode of gene regulation in plants. It is frequently controlled at initiation and appears to be regulated by competition for limiting translational components, different requirements for specific factors and cis-acting mRNA elements. Recent studies indicate that interactions between the 5' and 3' ends of the message enhance translation, perhaps by facilitating recruitment of initiation factors or enhancing ribosome recycling. Normal development and environmental stimuli modulate the phosphorylation of components of the mRNA 5'-cap-binding complex, ribosomes and mRNA-binding proteins. These modifications might be responsible for changes in the hierarchy of mRNAs that are in competition for translation.

Molecular and biochemical characterization of cytosolic phosphoglucomutase in maize. Expression during development and in response to oxygen deprivation.

Phosphoglucomutase (PGM) catalyzes the interconversion of glucose (Glc)-1- and Glc-6-phosphate in the synthesis and consumption of sucrose. We isolated two maize (Zea mays L.) cDNAs that encode PGM with 98.5% identity in their deduced amino acid sequence. Southern-blot analysis with genomic DNA from lines with different Pgm1 and Pgm2 genotypes suggested that the cDNAs encode the two known cytosolic PGM isozymes, PGM1 and PGM2. The cytosolic PGMs of maize are distinct from a plastidic PGM of spinach (Spinacia oleracea). The deduced amino acid sequences of the cytosolic PGMs contain the conserved phosphate-transfer catalytic center and the metal-ion-binding site of known prokaryotic and eukaryotic PGMs. PGM mRNA was detectable by RNA-blot analysis in all tissues and organs examined except silk. A reduction in PGM mRNA accumulation was detected in roots deprived of O2 for 24 h, along with reduced synthesis of a PGM identified as a 67-kD phosphoprotein on two-dimensional gels. Therefore, PGM is not one of the so-called "anaerobic polypeptides." Nevertheless, the specific activity of PGM was not significantly affected in roots deprived of O2 for 24 h. We propose that PGM is a stable protein and that existing levels are sufficient to maintain the flux of Glc-1-phosphate into glycolysis under O2 deprivation.

Evolutionary analyses of the 12-kDa acidic ribosomal P-proteins reveal a distinct protein of higher plant ribosomes.

The P-protein complex of eukaryotic ribosomes forms a lateral stalk structure in the active site of the large ribosomal subunit and is thought to assist in the elongation phase of translation by stimulating GTPase activity of elongation factor-2 and removal of deacylated tRNA. The complex in animals, fungi, and protozoans is composed of the acidic phosphoproteins P0 (35 kDa), P1 (11-12 kDa), and P2 (11-12 kDa). Previously we demonstrated by protein purification and microsequencing that ribosomes of maize (Zea mays L.) contain P0, one type of P1, two types of P2, and a distinct P1/P2 type protein designated P3. Here we implemented distance matrices, maximum parsimony, and neighbor-joining analyses to assess the evolutionary relationships between the 12 kDa P-proteins of maize and representative eukaryotic species. The analyses identify P3, found to date only in mono- and dicotyledonous plants, as an evolutionarily distinct P-protein. Plants possess three distinct groups of 12 kDa P-proteins (P1, P2, and P3), whereas animals, fungi, and protozoans possess only two distinct groups (P1 and P2). These findings demonstrate that the P-protein complex has evolved into a highly divergent complex with respect to protein composition despite its critical position within the active site of the ribosome.