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Parwinder S Grewal - One of the best experts on this subject based on the ideXlab platform.
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Moraxella osloensis Gene Expression in the Slug Host Deroceras reticulatum
BMC Microbiology, 2008Co-Authors: Srinand Sreevatsan, Parwinder S GrewalAbstract:Background The bacterium Moraxella osloensis is a mutualistic symbiont of the slug-parasitic nematode Phasmarhabditis hermaphrodita . In nature, P. hermaphrodita vectors M. osloensis into the shell cavity of the slug host Deroceras reticulatum in which the bacteria multiply and kill the slug. As M. osloensis is the main killing agent, genes expressed by M. osloensis in the slug are likely to play important roles in virulence. Studies on pathogenic interactions between bacteria and lower order hosts are few, but such studies have the potential to shed light on the evolution of bacterial virulence. Therefore, we investigated such an interaction by determining gene expression of M. osloensis in its slug host D. reticulatum by selectively capturing transcribed sequences. Results Thirteen M. osloensis genes were identified to be up-regulated post infection in D. reticulatum . Compared to the in vitro expressed genes in the stationary phase, we found that genes of ubiquinone synthetase ( ubiS ) and acyl-coA synthetase ( acs ) were up-regulated in both D. reticulatum and stationary phase in vitro cultures, but the remaining 11 genes were exclusively expressed in D. reticulatum and are hence infection specific. Mutational analysis on genes of protein-disulfide isomerase ( dsbC ) and ubiS showed that the virulence of both mutants to slugs was markedly reduced and could be complemented. Further, compared to the growth rate of wild-type M. osloensis , the dsbC and ubiS mutants showed normal and reduced growth rate in vitro , respectively. Conclusion We conclude that 11 out of the 13 up-regulated M. osloensis genes are infection specific. Distribution of these identified genes in various bacterial pathogens indicates that the virulence genes are conserved among different pathogen-host interactions. Mutagenesis, growth rate and virulence bioassays further confirmed that ubiS and dsbC genes play important roles in M. osloensis survival and virulence, respectively in D. reticulatum .
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infection behavior of the rhabditid nematode phasmarhabditis hermaphrodita to the grey garden slug Deroceras reticulatum
Journal of Parasitology, 2001Co-Authors: Li Tan, Parwinder S GrewalAbstract:Infection behavior of the rhabditid nematode Phasmarhabditis hermaphrodita to the grey garden slug Deroceras reticulatum was studied. The dauer (enduring or nonaging) juveniles of P. hermaphrodita invade D. reticulatum within 8–16 hr following external exposure, with the posterior mantle region containing the shell cavity serving as the main portal of entry. The dauer juveniles can recover, multiply, and produce new dauer juveniles in the slug and slug feces homogenates, but not in the soil extract. These results demonstrate that P. hermaphrodita is a facultative parasite of the slug and can complete its life cycle under nonparasitic conditions associated with the host. Although the juvenile and adult nematodes can kill the slug if injected into the shell cavity of the host, only the dauer juvenile can serve as an infective stage in the natural environment.
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pathogenicity of moraxella osloensis a bacterium associated with the nematode phasmarhabditis hermaphrodita to the slug Deroceras reticulatum
Applied and Environmental Microbiology, 2001Co-Authors: Li Tan, Parwinder S GrewalAbstract:Moraxella osloensis, a gram-negative bacterium, is associated with Phasmarhabditis hermaphrodita, a nematode parasite of slugs. This bacterium-feeding nematode has potential for the biological control of slugs, especially the grey garden slug, Deroceras reticulatum. Infective juveniles of P. hermaphrodita invade the shell cavity of the slug, develop into self-fertilizing hermaphrodites, and produce progeny, resulting in host death. However, the role of the associated bacterium in the pathogenicity of the nematode to the slug is unknown. We discovered that M. osloensis alone is pathogenic to D. reticulatum after injection into the shell cavity or hemocoel of the slug. The bacteria from 60-h cultures were more pathogenic than the bacteria from 40-h cultures, as indicated by the higher and more rapid mortality of the slugs injected with the former. Coinjection of penicillin and streptomycin with the 60-h bacterial culture reduced its pathogenicity to the slug. Further work suggested that the reduction and loss of pathogenicity of the aged infective juveniles of P. hermaphrodita to D. reticulatum result from the loss of M. osloensis from the aged nematodes. Also, axenic J1/J2 nematodes were nonpathogenic after injection into the shell cavity. Therefore, we conclude that the bacterium is the sole killing agent of D. reticulatum in the nematode-bacterium complex and that P. hermaphrodita acts only as a vector to transport the bacterium into the shell cavity of the slug. The identification of the toxic metabolites produced by M. osloensis is being pursued.
Robbie Rae - One of the best experts on this subject based on the ideXlab platform.
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chemoattraction and host preference of the gastropod parasitic nematode phasmarhabditis hermaphrodita
Journal of Parasitology, 2009Co-Authors: Robbie Rae, Jamie Robertson, Michael John WilsonAbstract:Abstract Phasmarhabditis hermaphrodita is a parasitic nematode that has been formulated into a biological control agent for slugs. The nematode responds to slug-associated cues such as mucus and feces in order to locate potential hosts. We assessed the olfactory response of P. hermaphrodita to mucus from 9 species of slugs, 2 snails, and 2 earthworms (non-hosts). We then examined the susceptibility of each invertebrate test species to high doses of P. hermaphrodita to determine whether susceptible species are more attractive than non-susceptible species to the nematode. We also studied the numbers of infective juveniles produced in each test species, as well as infectivity. Phasmarhabditis hermaphrodita showed strong attraction to mucus from the non-susceptible slug Arion subfuscus, the snail Helix aspersa, and the highly susceptible slug Deroceras reticulatum. In reproduction experiments, P. hermaphrodita produced the highest number of infective juveniles in D. reticulatum and Deroceras panormitanum; how...
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susceptibility and immune response of Deroceras reticulatum milax gagates and limax pseudoflavus exposed to the slug parasitic nematode phasmarhabditis hermaphrodita
Journal of Invertebrate Pathology, 2008Co-Authors: Jamie Robertson, Robbie Rae, Michael T WilsonAbstract:We exposed three slug species (Deroceras reticulatum (Muller), Milax gagates (Draparnaud) and Limax pseudoflavus L.) to the parasitic nematode Phasmarhabditis hermaphrodita Schneider. P. hermaphrodita was able to cause mortality and feeding inhibition to both D. reticulatum and M. gagates but did not negatively affect L. pseudoflavus. On dissection of surviving L. pseudoflavus large numbers of P. hermaphrodita were found encapsulated in the shell of the slug. We found that by increasing shell size, the slug was able to trap invading nematodes, which could be an immune response to P. hermaphrodita invasion. This is the first report of a slug defense mechanism to inhibit P. hermaphrodita.
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the chemotactic response of phasmarhabditis hermaphrodita nematoda rhabditida to cues of Deroceras reticulatum mollusca gastropoda
Nematology, 2006Co-Authors: Robbie Rae, Jamie Robertson, Michael T WilsonAbstract:Entomopathogenic nematodes use a range of cues released by insects to locate hosts but there has been no research on how the slug-parasitic nematode, Phasmarhabditis hermaphrodita, finds potential hosts. We exposed P. hermaphrodita to a range of cues associated with the highly susceptible host Deroceras reticulatum. Cues included foot and mantle mucus and faeces from live D. reticulatum and volatile cues released from this slug. We also compared the attractiveness of live and dead D. reticulatum, and the attractiveness of infected and non-infected D. reticulatum. Phasmarhabditis hermaphrodita responded poorly to volatile cues but was strongly attracted to live D. reticulatum, its faeces and mucus from both the foot and mantle. Phasmarhabditis hermaphrodita was attracted more to dead than live hosts, and was equally attracted to infected and non-infected D. reticulatum. The strong attraction to dead D. reticulatum adds weight to the hypothesis that this nematode is a facultative parasite that is capable of growth and reproduction on decaying plant and animal material present in soil.
Michael T Wilson - One of the best experts on this subject based on the ideXlab platform.
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susceptibility and immune response of Deroceras reticulatum milax gagates and limax pseudoflavus exposed to the slug parasitic nematode phasmarhabditis hermaphrodita
Journal of Invertebrate Pathology, 2008Co-Authors: Jamie Robertson, Robbie Rae, Michael T WilsonAbstract:We exposed three slug species (Deroceras reticulatum (Muller), Milax gagates (Draparnaud) and Limax pseudoflavus L.) to the parasitic nematode Phasmarhabditis hermaphrodita Schneider. P. hermaphrodita was able to cause mortality and feeding inhibition to both D. reticulatum and M. gagates but did not negatively affect L. pseudoflavus. On dissection of surviving L. pseudoflavus large numbers of P. hermaphrodita were found encapsulated in the shell of the slug. We found that by increasing shell size, the slug was able to trap invading nematodes, which could be an immune response to P. hermaphrodita invasion. This is the first report of a slug defense mechanism to inhibit P. hermaphrodita.
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the chemotactic response of phasmarhabditis hermaphrodita nematoda rhabditida to cues of Deroceras reticulatum mollusca gastropoda
Nematology, 2006Co-Authors: Robbie Rae, Jamie Robertson, Michael T WilsonAbstract:Entomopathogenic nematodes use a range of cues released by insects to locate hosts but there has been no research on how the slug-parasitic nematode, Phasmarhabditis hermaphrodita, finds potential hosts. We exposed P. hermaphrodita to a range of cues associated with the highly susceptible host Deroceras reticulatum. Cues included foot and mantle mucus and faeces from live D. reticulatum and volatile cues released from this slug. We also compared the attractiveness of live and dead D. reticulatum, and the attractiveness of infected and non-infected D. reticulatum. Phasmarhabditis hermaphrodita responded poorly to volatile cues but was strongly attracted to live D. reticulatum, its faeces and mucus from both the foot and mantle. Phasmarhabditis hermaphrodita was attracted more to dead than live hosts, and was equally attracted to infected and non-infected D. reticulatum. The strong attraction to dead D. reticulatum adds weight to the hypothesis that this nematode is a facultative parasite that is capable of growth and reproduction on decaying plant and animal material present in soil.
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feeding activity and survival of slugs Deroceras reticulatum exposed to the rhabditid nematode phasmarhabditis hermaphrodita a model of dose response
Biological Control, 2000Co-Authors: D M Glen, P. Brain, Michael T Wilson, G StroudAbstract:Abstract The slug, Deroceras reticulatum (Stylommatophora: Limacidae), was exposed to different concentrations of infective dauer juveniles of the rhabditid nematode Phasmarhabditis hermaphrodita, in a two-stage bioassay, at 10°C. Slugs were exposed in groups of 10 or 12 to nematodes in plastic boxes filled with soil aggregates for 3 or 5 days and then transferred individually to petri dishes each containing a disk of Chinese cabbage leaf as food. Subsequently, slug food consumption and survival were measured for 10 to 13 days. Models were developed to describe the way that exposure to the nematode caused inhibition of slug feeding followed by death. Both effects were related to nematode concentrations and time after exposure to the nematode. Following exposure to high concentrations (300,000 dauer juveniles per box), slugs were killed rapidly, within a few days after the end of the exposure period. Following exposure to low concentrations of nematodes (7000 or 15,000 per box), substantial numbers of slugs survived until the end of the bioassay, but feeding activity by these slugs was strongly inhibited. It is suggested that inhibition of slug feeding is important for the success of this nematode as a biocontrol agent.
Li Tan - One of the best experts on this subject based on the ideXlab platform.
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Characterization of the First Molluscicidal Lipopolysaccharide from Moraxella osloensis
American Society for Microbiology, 2003Co-Authors: Li Tan, Grewal, Parwinder S.Abstract:Moraxella osloensis is a bacterium that is mutualistically associated with Phasmarhabditis hermaphrodita, a nematode that has potential for the biocontrol of mollusk pests, especially the slug Deroceras reticulatum. We discovered that purified M. osloensis lipopolysaccharide (LPS) possesses a lethal toxicity to D. reticulatum when administered by injection but no contact or oral toxicity to this slug. The toxicity of the LPS resides in the lipid A moiety. M. osloensis LPS was semiquantitated at 6 × 10(7) endotoxin units per mg. The LPS is a rough-type LPS with an estimated molecular weight of 5,300. Coinjection of galactosamine with the LPS increased the LPS's toxicity to the slug two- to four-fold. The galactosamine-induced sensitization of the slug to the LPS was reversed completely by uridine
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Endotoxin Activity of Moraxella osloensis against the Grey Garden Slug, Deroceras reticulatum
American Society for Microbiology, 2002Co-Authors: Li Tan, Grewal, Parwinder S.Abstract:Moraxella osloensis is a gram-negative bacterium associated with Phasmarhabditis hermaphrodita, a slug-parasitic nematode that has prospects for biological control of mollusk pests, especially the grey garden slug, Deroceras reticulatum. This bacterium-feeding nematode acts as a vector that transports M. osloensis into the shell cavity of the slug, and the bacterium is the killing agent in the nematode-bacterium complex. We discovered that M. osloensis produces an endotoxin(s), which is tolerant to heat and protease treatments and kills the slug after injection into the shell cavity. Washed or broken cells treated with penicillin and streptomycin from 3-day M. osloensis cultures were more pathogenic than similar cells from 2-day M. osloensis cultures. However, heat and protease treatments and 2 days of storage at 22°C increased the endotoxin activity of the young broken cells but not the endotoxin activity of the young washed cells treated with the antibiotics. This suggests that there may be a proteinaceous substance(s) that is structurally associated with the endotoxin(s) and masks its toxicity in the young bacterial cells. Moreover, 2 days of storage of the young washed bacterial cells at 22°C enhanced their endotoxin activity if they were not treated with the antibiotics. Furthermore, purified lipopolysaccharide (LPS) from the 3-day M. osloensis cultures was toxic to slugs, with an estimated 50% lethal dose of 48 μg per slug, thus demonstrating that the LPS of M. osloensis is an endotoxin that is active against D. reticulatum. This appears to be the first report of a biological toxin that is active against mollusks
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infection behavior of the rhabditid nematode phasmarhabditis hermaphrodita to the grey garden slug Deroceras reticulatum
Journal of Parasitology, 2001Co-Authors: Li Tan, Parwinder S GrewalAbstract:Infection behavior of the rhabditid nematode Phasmarhabditis hermaphrodita to the grey garden slug Deroceras reticulatum was studied. The dauer (enduring or nonaging) juveniles of P. hermaphrodita invade D. reticulatum within 8–16 hr following external exposure, with the posterior mantle region containing the shell cavity serving as the main portal of entry. The dauer juveniles can recover, multiply, and produce new dauer juveniles in the slug and slug feces homogenates, but not in the soil extract. These results demonstrate that P. hermaphrodita is a facultative parasite of the slug and can complete its life cycle under nonparasitic conditions associated with the host. Although the juvenile and adult nematodes can kill the slug if injected into the shell cavity of the host, only the dauer juvenile can serve as an infective stage in the natural environment.
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pathogenicity of moraxella osloensis a bacterium associated with the nematode phasmarhabditis hermaphrodita to the slug Deroceras reticulatum
Applied and Environmental Microbiology, 2001Co-Authors: Li Tan, Parwinder S GrewalAbstract:Moraxella osloensis, a gram-negative bacterium, is associated with Phasmarhabditis hermaphrodita, a nematode parasite of slugs. This bacterium-feeding nematode has potential for the biological control of slugs, especially the grey garden slug, Deroceras reticulatum. Infective juveniles of P. hermaphrodita invade the shell cavity of the slug, develop into self-fertilizing hermaphrodites, and produce progeny, resulting in host death. However, the role of the associated bacterium in the pathogenicity of the nematode to the slug is unknown. We discovered that M. osloensis alone is pathogenic to D. reticulatum after injection into the shell cavity or hemocoel of the slug. The bacteria from 60-h cultures were more pathogenic than the bacteria from 40-h cultures, as indicated by the higher and more rapid mortality of the slugs injected with the former. Coinjection of penicillin and streptomycin with the 60-h bacterial culture reduced its pathogenicity to the slug. Further work suggested that the reduction and loss of pathogenicity of the aged infective juveniles of P. hermaphrodita to D. reticulatum result from the loss of M. osloensis from the aged nematodes. Also, axenic J1/J2 nematodes were nonpathogenic after injection into the shell cavity. Therefore, we conclude that the bacterium is the sole killing agent of D. reticulatum in the nematode-bacterium complex and that P. hermaphrodita acts only as a vector to transport the bacterium into the shell cavity of the slug. The identification of the toxic metabolites produced by M. osloensis is being pursued.
Monica Cortez - One of the best experts on this subject based on the ideXlab platform.
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control de babosas Deroceras reticulatum muller con phasmarhabditis hermaphrodita schneider nematoda rhabditidae en suelos con sistema de cero labranza
Agricultura Técnica v.62 n.2 2002, 2020Co-Authors: Marcos Gerding, Cecilia Cespedes, Monica CortezAbstract:Se evaluo el efecto del nematodo Phasmarhabditis hermaphrodita (Schneider) en el control de babosas (Deroceras reticulatum Muller) en condiciones de laboratorio y campo. El nematodo fue introducido desde Inglaterra. Luego de la cuarentena, P. hermaphrodita fue inoculado en D. reticulatum y evaluado diariamente por sintomas y mortalidad. En laboratorio el nematodo causo la mortalidad de la totalidad de las poblaciones de babosas a los 20 dias de postinoculacion, produciendo una notoria disminucion del apetito desde los primeros dias de la inoculacion. En terreno, los experimentos se realizaron en campos de cero labranza, con una poblacion de babosas que supero los 100 ejemplares m-2. Las siembras de lupino (Lupinus albus L.) tratadas con nematodos tuvieron una disminucion significativa de 51% menos de dano, comparadas con las siembras sin control. Tambien se observo un efecto significativo en el cultivo de maiz (Zea mays L.) como segunda siembra, reflejado en que el maiz sembrado en las parcelas tratadas con nematodos en el cultivo anterior, mantuvieron una disminucion en las plantas danadas por babosas y el consumo de area foliar decrecio entre 61a 89%, comparado con las parcelas testigos.
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CONTROL DE BABOSAS (Deroceras reticulatum Müller) CON Phasmarhabditis hermaphrodita Schneider (NEMATODA: RHABDITIDAE) EN SUELOS CON SISTEMA DE CERO LABRANZA (Slug control (Derocera reticulatum Müller) with Phasmarhabditis hermaphrodita Schneider (Nematoda: Rhabditidae) in non-tillage crop systems)
Instituto de Investigaciones Agropecuarias INIA, 2002Co-Authors: Andrés France, Marcos Gerding, Cecilia Cespedes, Monica CortezAbstract:The effect of the rhabditid nematode Phasmarhabditis hermaphrodita (Schneider) for slug ( Deroceras reticulatum Müller) control was evaluated in laboratory and farm conditions. The nematode was introduced from England. After quarantine, P. hermaphrodita was inoculated in D. reticulatum slugs and daily evaluated for symptoms and mortality. In the laboratory, the total population of slugs was killed by the nematode within 20 days, however, the food intake by slugs decreased from the first day of inoculation. The farm experiment was conducted in a non-tillage lupine ( Lupinus albus L.) crop system, with a population of slugs that exceeded 100 individuals m -2 . The nematode treated plots had 51% less slug damage compared with the control plots. Furthermore, a significant effect of the nematode was observed in the following corn ( Zea mays L.) crop, indicating that the corn planted in nematode treated plots the prior crop, maintained a reduction in the plants damaged by slugs and the foliar consumption decreased between 61 and 89% compared to the control plots