scholarly journals The entomopathogenic nematode Steinernema hermaphroditum is a self-fertilizing hermaphrodite and a genetically tractable system for the study of parasitic and mutualistic symbiosis

2021 ◽  
Author(s):  
Mengyi Cao ◽  
Hillel T. Schwartz ◽  
Chieh-Hsiang Tan ◽  
Paul W. Sternberg
Keyword(s):  
Entomopathogenic Nematodes ◽  
Genetic Model ◽  
Entomopathogenic Nematode ◽  
Model Development ◽  
Symbiotic Bacteria ◽  
Mutualistic Symbiosis ◽  
Self Fertilization ◽  
Rapid Generation ◽  
Mutant Lines

AbstractEntomopathogenic nematodes, including Heterorhabditis and Steinernema, are parasitic to insects and contain mutualistically symbiotic bacteria in their intestines (Photorhabdus and Xenorhabdus, respectively) and therefore offer opportunities to study both mutualistic and parasitic symbiosis. The establishment of genetic tools in entomopathogenic nematodes has been impeded by limited genetic tractability, inconsistent growth in vitro, variable cryopreservation, and low mating efficiency. We obtained the recently described Steinernema hermaphroditum strain CS34 and optimized its in vitro growth, with a rapid generation time on a lawn of its native symbiotic bacteria Xenorhabdus griffiniae. We developed a simple and efficient cryopreservation method. Previously, S. hermaphroditum isolated from insect hosts was described as first-generation hermaphroditic and second-generation gonochoristic. We discovered that CS34, when grown in vitro, produced consecutive generations of autonomously reproducing hermaphrodites accompanied by rare males. We performed mutagenesis screens in S. hermaphroditum that produced mutant lines with visible and heritable phenotypes. Genetic analysis of the mutants demonstrated that this species reproduces by self-fertilization rather than parthenogenesis and that its sex is determined chromosomally. Genetic mapping has thus far identified markers on the X chromosome and three of four autosomes. We report that S. hermaphroditum CS34 is the first consistently hermaphroditic entomopathogenic nematode and is suitable for genetic model development to study naturally occurring mutualistic symbiosis and insect parasitism.

scholarly journals The entomopathogenic nematode Steinernema hermaphroditum is a self-fertilizing hermaphrodite and a genetically tractable system for the study of parasitic and mutualistic symbiosis

Genetics ◽  
2021 ◽  
Author(s):  
Mengyi Cao ◽  
Hillel T Schwartz ◽  
Chieh-Hsiang Tan ◽  
Paul W Sternberg
Keyword(s):  
Entomopathogenic Nematodes ◽  
Genetic Model ◽  
Entomopathogenic Nematode ◽  
Model Development ◽  
Symbiotic Bacteria ◽  
Mutualistic Symbiosis ◽  
Self Fertilization ◽  
Rapid Generation ◽  
Mutant Lines

Abstract Entomopathogenic nematodes, including Heterorhabditis and Steinernema, are parasitic to insects and contain mutualistically symbiotic bacteria in their intestines (Photorhabdus and Xenorhabdus, respectively) and therefore offer opportunities to study both mutualistic and parasitic symbiosis. The establishment of genetic tools in entomopathogenic nematodes has been impeded by limited genetic tractability, inconsistent growth in vitro, variable cryopreservation, and low mating efficiency. We obtained the recently described Steinernema hermaphroditum strain CS34 and optimized its in vitro growth, with a rapid generation time on a lawn of its native symbiotic bacteria Xenorhabdus griffiniae. We developed a simple and efficient cryopreservation method. Previously, S. hermaphroditum isolated from insect hosts was described as producing hermaphrodites in the first generation. We discovered that CS34, when grown in vitro, produced consecutive generations of autonomously reproducing hermaphrodites accompanied by rare males. We performed mutagenesis screens in S. hermaphroditum that produced mutant lines with visible and heritable phenotypes. Genetic analysis of the mutants demonstrated that this species reproduces by self-fertilization rather than parthenogenesis and that its sex is determined chromosomally. Genetic mapping has thus far identified markers on the X chromosome and three of four autosomes. We report that S. hermaphroditum CS34 is the first consistently hermaphroditic entomopathogenic nematode and is suitable for genetic model development to study naturally occurring mutualistic symbiosis and insect parasitism.

Physico-chemical properties and mode of action of a signal from the symbiotic bacterium Photorhabdus luminescens inducing dauer juvenile recovery in the entomopathogenic nematode Heterorhabditis bacteriophora

Nematology ◽  
2001 ◽  
Vol 3 (8) ◽  
pp. 849-853 ◽  
Author(s):  
Ralf-Udo Ehlers ◽  
Jens Aumann
Keyword(s):  
Entomopathogenic Nematodes ◽  
Entomopathogenic Nematode ◽  
Chemical Properties ◽  
Symbiotic Bacterium ◽  
Heterorhabditis Bacteriophora ◽  
Juvenile Stage ◽  
Food Sources ◽  
Symbiotic Bacteria ◽  
Photorhabdus Luminescens ◽  
Physico Chemical

AbstractRecovery in entomopathogenic nematodes is the exit from the dauer juvenile stage. It is a response to environmental queues signalling the presence of food sources (e.g., insect haemolymph). The bacterium Photorhabdus luminescens excretes a signal which also induces recovery of its symbiotic Heterorhabditis bacteriophora dauer juveniles. This bacterial signal is composed of at least two compounds with different polarity. The symbiotic bacteria also secrete an antagonistic signal which inhibits nematode recovery. The recovery-inducing signal compounds have a molecular mass of less than 20 kDa and are negatively charged. The data indicate that at least one compound is smaller than 5 kDa. The bacterial signal triggers by receptor binding, the first step in a recovery-inducing muscarinic signalling pathway.

scholarly journals Cold tolerance of entomopathogenic nematodes

2009 ◽  
Vol 62 ◽  
pp. 396-396
Author(s):  
F. Ali ◽  
D.A. Wharton
Keyword(s):  
Large Scale ◽  
Entomopathogenic Nematodes ◽  
Entomopathogenic Nematode ◽  
Freeze Substitution ◽  
Slow Freezing ◽  
Steinernema Feltiae ◽  
Commercial Application ◽  
Subzero Temperature ◽  
Cold Stage

Entomopathogenic nematodes in the Steinernematidae and Heterorhabditidae families are lethal parasites of insects They have great potential as biological control agents since they can be mass produced in vitro However their limited shelf life is the major impediment to their large scale commercial application Attempts to base a storage technology on partial desiccation and anhydrobiosis have met with limited success The natural capacity of entomopathogenic nematodes for freezing tolerance could be an alternative to be exploited as a first step towards developing a method for their longterm storage In the present laboratory experiments the entomopathogenic nematode Steinernema feltiae has shown to be freezetolerant if frozen at relatively high subzero temperature with survival near the level of controls However slow freezing at high subzero temperature (1C) enhanced the nematodes survival at lower temperatures (down to 12C) Freezing of the nematodes was confirmed under the cold stage microscope although the mechanism of survival in the slow freezing regime was difficult to visualise through cold stage microscopy This mechanism needs to be investigated further via a different technique such as freeze substitution and electron microscopy Neither acclimation nor rapid cold hardening improved the survival of nematodes significantly

scholarly journals Effect of the entomopathogenic nematode Steinernema Glaseri (Rhabditida: Steinernematidae) isolate Santa Rosa on the biological parameters of engorged nymphs of Amblyomma Cajennense (Acari: Ixodidae)

2013 ◽  
Vol 80 (2) ◽  
pp. 237-241 ◽  
Author(s):  
R. Cardoso ◽  
C. M.O. Monteiro ◽  
M.C.A. Prata ◽  
E.S.P. Batista
Keyword(s):  
Relative Humidity ◽  
Entomopathogenic Nematodes ◽  
Entomopathogenic Nematode ◽  
Biological Parameters ◽  
Amblyomma Cajennense ◽  
Steinernema Glaseri ◽  
Petri Dishes ◽  
In Vitro Effects ◽  
Mortality Percentage

This work evaluated the in vitro effects of Steinernema glaseri on the biology of engorged Amblyomma cajennense nymphs. The ticks were exposed to infective juveniles (IJs) of S. glaseri at different concentrations. Each treatment was composed by 10 experimental units (EU = repetitions) in Petri dishes maintained at 27 ± 1º C and relative humidity (RH) > 80 ± 10% for 72 hours. Then the nymphs were transferred to Petri dishes free of nematodes for observation of the following parameters: pre-ecdysis period (PEP), ecdysis period (EP), molting period (MP), ecdysis percentage (%Ec) and mortality percentage (%Mt). The groups treated with 5,000 and 10,000 IJs/EU showed significant alterations in the PEP when compared to the control, while for the EP only the treatment with 10,000 IJs/EU produced any significant changes compared to the control. The MP did not differ significantly from the control in any of the treated groups. For the %Ec only the group treated with 10,000 IJs/EU differed significantly from the control. The greatest efficiency was obtained at the concentration of 10,000 IJs/EU, in which the mortality percentage was 13%. This demonstrates that the nematode utilized was not able to cause high mortality in engorged A. cajennense nymphs and agrees with other reports indicating that immature ticks are not highly susceptible to entomopathogenic nematodes.

scholarly journals Response of Ants to a Deterrent Factor(s) Produced by the Symbiotic Bacteria of Entomopathogenic Nematodes

2002 ◽  
Vol 68 (12) ◽  
pp. 6202-6209 ◽  
Author(s):  
Xinsheng Zhou ◽  
Harry K. Kaya ◽  
Kurt Heungens ◽  
Heidi Goodrich-Blair
Keyword(s):  
Entomopathogenic Nematodes ◽  
Sucrose Concentration ◽  
In Vitro Assays ◽  
Symbiotic Bacteria ◽  
Xenorhabdus Nematophila ◽  
Bacterial Cultures ◽  
Heat Stable ◽  
Species Being

ABSTRACT The production of an ant-deterrent factor(s) (ADF) by Xenorhabdus nematophila and Photorhabdus luminescens, the symbiotic bacteria of the nematodes Steinernema carpocapsae and Heterorhabditis bacteriophora, respectively, was examined. In addition to an in vivo assay in which bacteria were tested for their ability to produce ADF within insect cadavers (M.E. Baur, H. K. Kaya, and D. R. Strong, Biol. Control 12:231-236, 1998), an in vitro microtiter dish assay was developed to monitor ADF activity produced by bacteria grown in cultures. Using these methods, we show that ADF activity is present in the supernatants of bacterial cultures, is filterable, heat stable, and acid sensitive, and passes through a 10-kDa-pore-size membrane. Thus, ADF appears to be comprised of a small, extracellular, and possibly nonproteinaceous compound(s). The amount of ADF repellency detected depends on the ant species being tested, the sucrose concentration (in vitro assays), and the strain, form, and age of the ADF-producing bacteria. These findings demonstrate that the symbiotic bacteria of some species of entomopathogenic nematodes produce a compound(s) that deters scavengers such as ants and thus could protect nematodes from being eaten during reproduction within insect cadavers.

scholarly journals Evaluation in vitro of the infection times of engorged females of Rhipicephalus (Boophilus) microplus by the entomopathogenic nematode Steinernema glaseri CCA strain

2010 ◽  
Vol 40 (4) ◽  
pp. 939-943 ◽  
Author(s):  
Leandro Barbiéri de Carvalho ◽  
John Furlong ◽  
Márcia Cristina de Azevedo Prata ◽  
Éder Sebastião dos Reis ◽  
Elder Simões de Paula Batista ◽  
...  
Keyword(s):  
Exposure Time ◽  
Treatment Efficacy ◽  
Tick Species ◽  
Entomopathogenic Nematodes ◽  
Entomopathogenic Nematode ◽  
Boophilus Microplus ◽  
Development Phase ◽  
Biological Parameters ◽  
Steinernema Glaseri

Studies have shown that ticks are susceptible to infection by entomopathogenic nematodes. These studies indicate different susceptibilities of ticks to infection by these fungi, depending on the tick species, development phase, entomopathogenic nematodes species and strains and the time the ticks are exposed to them. Usually this period ranges from 24 to 72 hours. The aim of this study was to evaluate the infection times in vitro of engorged Rhipicephalus (Boophilus) microplus females by the entomopathogenic nematodes Steinernema glaseri CCA strain, by analysis of the ticks' biological parameters. The results show that a 2-hour exposure time was sufficient for the engorged R. microplus females to be infected by S. glaseri CCA, but that a minimum exposure time of 24 hours was necessary to generate treatment efficacy above 90%.

scholarly journals Mass Cultivation of Entomopathogenic Nematode in Artificial Media

2016 ◽  
Vol 8 (1) ◽  
pp. 111 ◽  
Author(s):  
Dyah Rini Indriyanti ◽  
Nur Lailatul Muharromah
Keyword(s):  
Entomopathogenic Nematodes ◽  
Entomopathogenic Nematode ◽  
Biology Education ◽  
Chicken Liver ◽  
Dog Food ◽  
Mass Cultivation ◽  
Soybean Powder ◽  
Food Media

<p>Entomopathogenic nematodes Entomopathogenic nematodes (EPN) of the genera Heterorhabditis and Steinernema are commercially used to control pest insect. EPN is widely cultivated through in-vivo and in vitro methods. This research aims to discover the abundance of EPN cultivated in various artificial media. Seven types of media composition were tested in this research: media A (yeast + soybean powder), media B (yeast + chicken liver), media C (yeast + dog food), media D (yolk + soybean powder), media E (yolk + chicken liver), media F (yolk + dog food), and media G (yeast + yolk + dog food). Each media was inoculated in 1.2x103JI/mL. The growth of EPN was observed weekly in 4 weeks. Results showed that EPN could be cultivated using various media; media D, E, F, and G. Highest abundance of EPN is found in the second week of media D for 28164 JI/ml.Cell harvesting is suggested to be conducted during the first and second week to obtain maximum abundance of EPN.</p><p><strong>How to Cite</strong></p><p>Indriyanti, D., &amp; Muharromah, N. (2016). Mass Cultivation of Entomopathogenic Nematode In Artificial Media.<em> Biosaintifika: Journal of Biology &amp; Biology Education</em>, 8(1), 111-118.</p>

Early Platelet-Collagen Interactions in Whole Blood and Their Modifications by Aspirin and Dipyridamole Evaluated by a New Method (Basic Wave)

1985 ◽  
Vol 54 (04) ◽  
pp. 799-803 ◽  
Author(s):  
José Luís Pérez-Requejo ◽  
Justo Aznar ◽  
M Teresa Santos ◽  
Juana Vallés
Keyword(s):  
Whole Blood ◽  
Ex Vivo ◽  
Platelet Rich Plasma ◽  
White Blood Cells ◽  
Reversible Aggregation ◽  
Inhibitory Compounds ◽  
Rapid Generation ◽  
Stimulation Of ◽  
Collagen Stimulation

SummaryIt is shown that the supernatant of unstirred whole blood at 37° C, stimulated by 1 μg/ml of collagen for 10 sec, produces a rapid generation of pro and antiaggregatory compounds with a final proaggregatory activity which can be detected for more than 60 min on a platelet rich plasma (PRP) by turbidometric aggregometry. A reversible aggregation wave that we have called BASIC wave (for Blood Aggregation Stimulatory and Inhibitory Compounds) is recorded. The collagen stimulation of unstirred PRP produces a similar but smaller BASIC wave. BASIC’s intensity increases if erythrocytes are added to PRP but decreases if white blood cells are added instead. Aspirin abolishes “ex vivo” the ability of whole blood and PRP to generate BASIC waves and dipyridamole “in vitro” significantly reduces BASIC’s intensity in whole blood in every tested sample, but shows little effect in PRP.

scholarly journals Characterization of symbiotic and associated bacteria from entomopathogenic nematode Heterorhabditis sp. (nematode: Heterorhabditidae) isolated from India

2020 ◽  
Vol 30 (1) ◽  
Author(s):  
Rashid Pervez ◽  
Showkat Ahmad Lone ◽  
Sasmita Pattnaik
Keyword(s):  
Insect Pests ◽  
Entomopathogenic Nematode ◽  
Alcaligenes Faecalis ◽  
Symbiotic Bacteria ◽  
Rrna Gene ◽  
Main Body ◽  
Associated Bacteria ◽  
Molecular Approaches

Abstract Background Entomopathogenic nematodes (EPNs) harboring symbiotic bacteria are one of the safest alternatives to the chemical insecticides for the control of various insect pests. Infective juveniles of EPNs locate a target insect, enter through the openings, and reach the hemocoel, where they release the symbiotic bacteria and the target gets killed by the virulence factors of the bacteria. Photorhabdus with Heterorhabditis spp. are well documented; little is known about the associated bacteria. Main body In this study, we explored the presence of symbiotic and associated bacteria from Heterorhabditis sp. (IISR-EPN 09) and characterized by phenotypic, biochemical, and molecular approaches. Six bacterial isolates, belonging to four different genera, were recovered and identified as follows: Photorhabdus luminescens, one each strain of Providencia vermicola, Pseudomonas entomophila, Alcaligenes aquatilis, and two strains of Alcaligenes faecalis based on the phenotypic, biochemical criteria and the sequencing of 16S rRNA gene. Conclusion P. luminescens is symbiotically associated with Heterorhabditis sp. (IISR-EPN 09), whereas P. vermicola, P. entomophila, A. aquatilis, and A. faecalis are the associated bacteria. Further studies are needed to determine the exact role of the bacterial associates with the Heterorhabditis sp.

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