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Patuwatha Withanage DBM, Luong LT. CHEMOTAXIS RESPONSE OF PHASMARHABDITIS CALIFORNICA (FAMILY: RHABDITIDAE) AND PRISTIONCHUS ENTOMOPHAGUS (FAMILY: NEODIPLOGASTERIDAE) TO THE MUCUS OF FOUR SLUG SPECIES. J Parasitol 2024; 110:59-65. [PMID: 38381123 DOI: 10.1645/23-61] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2024] Open
Abstract
The chemotaxis responses of soil nematodes have been well studied in bacteriophagic nematodes, plant-parasitic nematodes, entomopathogenic nematodes, and to a lesser extent malacopathogenic nematodes. Free-living stages of parasitic nematodes often use chemotaxis to locate hosts. In this study, we compared the chemotaxis profile of 2 slug-associated nematodes with overlapping host ranges. Phasmarhabditis californica is a facultative parasite that has been shown to express strain-dependent variation in chemoattraction profile. We tested 4 slug species to determine the attraction index of a Canadian strain of Ph. californica and a sympatric necromenic nematode, Pristionchus entomophagus. When tested against a control (distilled water), Ph. californica showed a clear (positive) attraction towards the mucus of slugs Ambigolimax valentianus, Arion rufus, and Arion fasciatus, but not Deroceras reticulatum. However, when given a choice between the mucus of D. reticulatum and Ar. fasciatus in a pairwise test, Ph. californica was strongly attracted to the former. Other pairwise comparisons did not reveal a clear preference for either slug species in the following pairs: D. reticulatum-Ar. rufus, Am. valentianus-Ar. rufus, D. reticulatum-Am. valentianus. The chemotaxis assay for Pr. entomophagus showed an attraction toward D. reticulatum and Ar. fasciatus (tested against controls); the attraction index for Am. valentianus was positive, but this was not statistically significant. In contrast, the attraction index for Ar. rufus was negative, suggesting possible repulsion to the mucus of this slug species. Given that Pr. entomophagus and Ph. californica occupy overlapping habitats, utilize similar hosts, and exhibit similar chemotaxis profiles, there is a potential for direct interaction between these 2 nematodes. Like other members of the genus Pristionchus, Pr. entomophagus may be able to prey upon the co-occurring Ph. californica, such antagonistic interactions could have important implications for the coexistence of these 2 species and Ph. californica in particular as a biocontrol agent against pestiferous slugs.
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Affiliation(s)
| | - Lien T Luong
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
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2
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Kalirad A, Sommer RJ. The role of plasticity and stochasticity in coexistence. Ecol Lett 2024; 27:e14370. [PMID: 38348631 DOI: 10.1111/ele.14370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 12/12/2023] [Accepted: 12/18/2023] [Indexed: 02/15/2024]
Abstract
Species coexistence in ecological communities is a central feature of biodiversity. Different concepts, i.e., contemporary niche theory, modern coexistence theory, and the unified neutral theory, have identified many building blocks of such ecological assemblies. However, other factors, such as phenotypic plasticity and stochastic inter-individual variation, have received little attention, in particular in animals. For example, how resource polyphenisms resulting in predator-prey interactions affect coexistence is currently unknown. Here, we present an integrative theoretical-experimental framework using the nematode plasticity model Pristionchus pacificus with its well-studied mouth-form dimorphism resulting in cannibalism. We develop an individual-based model that relies upon synthetic data based on our empirical measurements of fecundity and polyphenism to preserve demographic heterogeneity. We demonstrate how the interplay between plasticity and individual stochasticity result in all-or-nothing outcomes at the local level. Coexistence is made possible when spatial structure is introduced.
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Affiliation(s)
- Ata Kalirad
- Department for Integrative Evolutionary Biology, Max Planck Institute for Biology Tübingen, Tübingen, Germany
| | - Ralf J Sommer
- Department for Integrative Evolutionary Biology, Max Planck Institute for Biology Tübingen, Tübingen, Germany
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3
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Hiramatsu F, Lightfoot JW. Kin-recognition and predation shape collective behaviors in the cannibalistic nematode Pristionchus pacificus. PLoS Genet 2023; 19:e1011056. [PMID: 38096160 PMCID: PMC10721034 DOI: 10.1371/journal.pgen.1011056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Accepted: 11/08/2023] [Indexed: 12/17/2023] Open
Abstract
Kin-recognition is observed across diverse species forming an important behavioral adaptation influencing organismal interactions. In many species, the molecular mechanisms involved are difficult to characterize, but in the nematode Pristionchus pacificus molecular components regulating its kin-recognition system have been identified. These determine its predatory behaviors towards other con-specifics which prevents the killing and cannibalization of kin. Importantly, their impact on other interactions including collective behaviors is unknown. Here, we explored a high altitude adapted clade of this species which aggregates abundantly under laboratory conditions, to investigate the influence of the kin-recognition system on their group behaviours. By utilizing pairwise aggregation assays between distinct strains of P. pacificus with differing degrees of genetic relatedness, we observe aggregation between kin but not distantly related strains. In assays between distantly related strains, the aggregation ratio is frequently reduced. Furthermore, abolishing predation behaviors through CRISPR/Cas9 induced mutations in Ppa-nhr-40 result in rival strains successfully aggregating together. Finally, as Caenorhabditis elegans are found naturally occurring with P. pacificus, we also explored aggregation events between these species. Here, aggregates were dominated by P. pacificus with the presence of only a small number of predators proving sufficient to disrupt C. elegans aggregation dynamics. Thus, aggregating strains of P. pacificus preferentially group with kin, revealing competition and nepotism as previously unknown components influencing collective behaviors in nematodes.
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Affiliation(s)
- Fumie Hiramatsu
- Max Planck Research Group Genetics of Behavior, Max Planck Institute for Neurobiology of Behavior–caesar, Bonn, Germany
- International Max Planck Research School for Brain and Behavior, Bonn, Germany
| | - James W. Lightfoot
- Max Planck Research Group Genetics of Behavior, Max Planck Institute for Neurobiology of Behavior–caesar, Bonn, Germany
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4
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O’Rourke D, Gravato-Nobre MJ, Stroud D, Pritchett E, Barker E, Price RL, Robinson SA, Spiro S, Kuwabara P, Hodgkin J. Isolation and molecular identification of nematode surface mutants with resistance to bacterial pathogens. G3 (BETHESDA, MD.) 2023; 13:jkad056. [PMID: 36911920 PMCID: PMC10151413 DOI: 10.1093/g3journal/jkad056] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 02/16/2023] [Accepted: 02/22/2023] [Indexed: 03/14/2023]
Abstract
Numerous mutants of the nematode Caenorhabditis elegans with surface abnormalities have been isolated by utilizing their resistance to a variety of bacterial pathogens (Microbacterium nematophilum, Yersinia pseudotuberculosis, and 2 Leucobacter strains), all of which are able to cause disease or death when worms are grown on bacterial lawns containing these pathogens. Previous work led to the identification of 9 srf or bus genes; here, we report molecular identification and characterization of a further 10 surface-affecting genes. Three of these were found to encode factors implicated in glycosylation (srf-2, bus-5, and bus-22), like several of those previously reported; srf-2 belongs to the GT92 family of putative galactosyltransferases, and bus-5 is homologous to human dTDP-D-glucose 4,6-dehydratase, which is implicated in Catel-Manzke syndrome. Other genes encoded proteins with sequence similarity to phosphatidylinositol phosphatases (bus-6), Patched-related receptors (ptr-15/bus-13), steroid dehydrogenases (dhs-5/bus-21), or glypiation factors (bus-24). Three genes appeared to be nematode-specific (srf-5, bus-10, and bus-28). Many mutants exhibited cuticle fragility as revealed by bleach and detergent sensitivity; this fragility was correlated with increased drug sensitivity, as well as with abnormal skiddy locomotion. Most of the genes examined were found to be expressed in epidermal seam cells, which appear to be important for synthesizing nematode surface coat. The results reveal the genetic and biochemical complexity of this critical surface layer, and provide new tools for its analysis.
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Affiliation(s)
- Delia O’Rourke
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | | | - Dave Stroud
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Emily Pritchett
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Emily Barker
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Rebecca L Price
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Sarah A Robinson
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Simon Spiro
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | | | - Jonathan Hodgkin
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
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Dardiry M, Piskobulu V, Kalirad A, Sommer RJ. Experimental and theoretical support for costs of plasticity and phenotype in a nematode cannibalistic trait. Evol Lett 2023; 7:48-57. [PMID: 37065436 PMCID: PMC10091500 DOI: 10.1093/evlett/qrac001] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 11/01/2022] [Accepted: 12/06/2022] [Indexed: 02/04/2023] Open
Abstract
Abstract
Developmental plasticity is the ability of a genotype to express multiple phenotypes under different environmental conditions and has been shown to facilitate the evolution of novel traits. However, while the associated cost of plasticity, i.e., the loss in fitness due to the ability to express plasticity in response to environmental change, and the cost of phenotype, i.e., the loss of fitness due to expressing a fixed phenotype across environments, have been theoretically predicted, empirically such costs remain poorly documented and little understood. Here, we use a plasticity model system, hermaphroditic nematode Pristionchus pacificus, to experimentally measure these costs in wild isolates under controlled laboratory conditions. P. pacificus can develop either a bacterial feeding or predatory mouth morph in response to different external stimuli, with natural variation of mouth-morph ratios between strains. We first demonstrated the cost of phenotype by analyzing fecundity and developmental speed in relation to mouth morphs across the P. pacificus phylogenetic tree. Then, we exposed P. pacificus strains to two distinct microbial diets that induce strain-specific mouth-form ratios. Our results indicate that the plastic strain does shoulder a cost of plasticity, i.e., the diet-induced predatory mouth morph is associated with reduced fecundity and slower developmental speed. In contrast, the non-plastic strain suffers from the cost of phenotype since its phenotype does not change to match the unfavorable bacterial diet but shows increased fitness and higher developmental speed on the favorable diet. Furthermore, using a stage-structured population model based on empirically derived life history parameters, we show how population structure can alleviate the cost of plasticity in P. pacificus. The results of the model illustrate the extent to which the costs associated with plasticity and its effect on competition depend on ecological factors. This study provides support for costs of plasticity and phenotype based on empirical and modeling approaches.
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Affiliation(s)
- Mohannad Dardiry
- Department for Integrative Evolutionary Biology, Max Planck Institute for Biology Tübingen , Tübingen , Germany
| | - Veysi Piskobulu
- Department for Integrative Evolutionary Biology, Max Planck Institute for Biology Tübingen , Tübingen , Germany
| | - Ata Kalirad
- Department for Integrative Evolutionary Biology, Max Planck Institute for Biology Tübingen , Tübingen , Germany
| | - Ralf J Sommer
- Department for Integrative Evolutionary Biology, Max Planck Institute for Biology Tübingen , Tübingen , Germany
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6
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Quach KT, Chalasani SH. Flexible reprogramming of Pristionchus pacificus motivation for attacking Caenorhabditis elegans in predator-prey competition. Curr Biol 2022; 32:1675-1688.e7. [PMID: 35259340 PMCID: PMC9050875 DOI: 10.1016/j.cub.2022.02.033] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 12/18/2021] [Accepted: 02/09/2022] [Indexed: 12/16/2022]
Abstract
Animals with diverse diets must adapt their food priorities to a wide variety of environmental conditions. This diet optimization problem is especially complex for predators that compete with prey for food. Although predator-prey competition is widespread and ecologically critical, it remains difficult to disentangle predatory and competitive motivations for attacking competing prey. Here, we dissect the foraging decisions of the omnivorous nematode Pristionchus pacificus to reveal that its seemingly failed predatory attempts against Caenorhabditis elegans are actually motivated acts of efficacious territorial aggression. While P. pacificus easily kills and eats larval C. elegans with a single bite, adult C. elegans typically survives and escapes bites. However, non-fatal biting can provide competitive benefits by reducing access of adult C. elegans and its progeny to bacterial food that P. pacificus also eats. We show that the costs and benefits of both predatory and territorial outcomes influence how P. pacificus decides which food goal, prey or bacteria, should guide its motivation for biting. These predatory and territorial motivations impose different sets of rules for adjusting willingness to bite in response to changes in bacterial abundance. In addition to biting, predatory and territorial motivations also influence which search tactic P. pacificus uses to increase encounters with C. elegans. When treated with an octopamine receptor antagonist, P. pacificus switches from territorial to predatory motivation for both biting and search. Overall, we demonstrate that P. pacificus assesses alternate outcomes of attacking C. elegans and flexibly reprograms its foraging strategy to prioritize either prey or bacterial food.
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Affiliation(s)
- Kathleen T. Quach
- Neurosciences Graduate Program, University of California San Diego, Gilman Drive, La Jolla, CA 92037, USA.,Molecular Neurobiology Laboratory, Salk Institute for Biological Studies, North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Sreekanth H. Chalasani
- Neurosciences Graduate Program, University of California San Diego, Gilman Drive, La Jolla, CA 92037, USA.,Molecular Neurobiology Laboratory, Salk Institute for Biological Studies, North Torrey Pines Road, La Jolla, CA 92037, USA.,Lead Contact,Correspondence: , Twitter: @shreklab
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Igreja C, Sommer RJ. The Role of Sulfation in Nematode Development and Phenotypic Plasticity. Front Mol Biosci 2022; 9:838148. [PMID: 35223994 PMCID: PMC8869759 DOI: 10.3389/fmolb.2022.838148] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Accepted: 01/24/2022] [Indexed: 12/25/2022] Open
Abstract
Sulfation is poorly understood in most invertebrates and a potential role of sulfation in the regulation of developmental and physiological processes of these organisms remains unclear. Also, animal model system approaches did not identify many sulfation-associated mechanisms, whereas phosphorylation and ubiquitination are regularly found in unbiased genetic and pharmacological studies. However, recent work in the two nematodes Caenorhabditis elegans and Pristionchus pacificus found a role of sulfatases and sulfotransferases in the regulation of development and phenotypic plasticity. Here, we summarize the current knowledge about the role of sulfation in nematodes and highlight future research opportunities made possible by the advanced experimental toolkit available in these organisms.
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Affiliation(s)
- Catia Igreja
- *Correspondence: Catia Igreja, ; Ralf J. Sommer,
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8
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Sun S, Theska T, Witte H, Ragsdale EJ, Sommer RJ. The oscillating Mucin-type protein DPY-6 has a conserved role in nematode mouth and cuticle formation. Genetics 2021; 220:6481560. [PMID: 35088845 PMCID: PMC9208649 DOI: 10.1093/genetics/iyab233] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Accepted: 12/13/2021] [Indexed: 01/09/2023] Open
Abstract
Nematodes show an extraordinary diversity of mouth structures and strikingly different feeding strategies, which has enabled an invasion of all ecosystems. However, nearly nothing is known about the structural and molecular architecture of the nematode mouth (stoma). Pristionchus pacificus is an intensively studied nematode that exhibits unique life history traits, including predation, teeth-like denticle formation, and mouth-form plasticity. Here, we used a large-scale genetic screen to identify genes involved in mouth formation. We identified Ppa-dpy-6 to encode a Mucin-type hydrogel-forming protein that is macroscopically involved in the specification of the cheilostom, the anterior part of the mouth. We used a recently developed protocol for geometric morphometrics of miniature animals to characterize these defects further and found additional defects that affect mouth form, shape, and size resulting in an overall malformation of the mouth. Additionally, Ppa-dpy-6 is shorter than wild-type with a typical Dumpy phenotype, indicating a role in the formation of the external cuticle. This concomitant phenotype of the cheilostom and cuticle provides the first molecular support for the continuity of these structures and for the separation of the cheilostom from the rest of the stoma. In Caenorhabditis elegans, dpy-6 was an early mapping mutant but its molecular identity was only determined during genome-wide RNAi screens and not further investigated. Strikingly, geometric morphometric analysis revealed previously unrecognized cheilostom and gymnostom defects in Cel-dpy-6 mutants. Thus, the Mucin-type protein DPY-6 represents to the best of our knowledge, the first protein involved in nematode mouth formation with a conserved role in cuticle deposition. This study opens new research avenues to characterize the molecular composition of the nematode mouth, which is associated with extreme ecological diversification.
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Affiliation(s)
- Shuai Sun
- Department for Integrative Evolutionary Biology, Max Planck Institute for Biology Tübingen, 72076 Tübingen, Germany
| | - Tobias Theska
- Department for Integrative Evolutionary Biology, Max Planck Institute for Biology Tübingen, 72076 Tübingen, Germany
| | - Hanh Witte
- Department for Integrative Evolutionary Biology, Max Planck Institute for Biology Tübingen, 72076 Tübingen, Germany
| | - Erik J Ragsdale
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Ralf J Sommer
- Department for Integrative Evolutionary Biology, Max Planck Institute for Biology Tübingen, 72076 Tübingen, Germany,Corresponding author: Department for Integrative Evolutionary Biology, Max Planck Institute for Biology Tübingen, Max-Planck Ring 9, Tübingen 72076, Germany.
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9
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Lightfoot JW, Dardiry M, Kalirad A, Giaimo S, Eberhardt G, Witte H, Wilecki M, Rödelsperger C, Traulsen A, Sommer RJ. Sex or cannibalism: Polyphenism and kin recognition control social action strategies in nematodes. SCIENCE ADVANCES 2021; 7:7/35/eabg8042. [PMID: 34433565 PMCID: PMC8386922 DOI: 10.1126/sciadv.abg8042] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 07/01/2021] [Indexed: 05/10/2023]
Abstract
Resource polyphenisms, where single genotypes produce alternative feeding strategies in response to changing environments, are thought to be facilitators of evolutionary novelty. However, understanding the interplay between environment, morphology, and behavior and its significance is complex. We explore a radiation of Pristionchus nematodes with discrete polyphenic mouth forms and associated microbivorous versus cannibalistic traits. Notably, comparing 29 Pristionchus species reveals that reproductive mode strongly correlates with mouth-form plasticity. Male-female species exhibit the microbivorous morph and avoid parent-offspring conflict as indicated by genetic hybrids. In contrast, hermaphroditic species display cannibalistic morphs encouraging competition. Testing predation between 36 co-occurring strains of the hermaphrodite P. pacificus showed that killing inversely correlates with genomic relatedness. These empirical data together with theory reveal that polyphenism (plasticity), kin recognition, and relatedness are three major factors that shape cannibalistic behaviors. Thus, developmental plasticity influences cooperative versus competitive social action strategies in diverse animals.
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Affiliation(s)
- James W Lightfoot
- Max Planck Institute for Developmental Biology, Max-Planck Ring 9, 72076 Tübingen, Germany
- Max Planck Research Group Self-Recognition and Cannibalism, Center of Advanced European Studies and Research (CAESAR), Ludwig-Erhard-Allee 2, Bonn 53175, Germany
| | - Mohannad Dardiry
- Max Planck Institute for Developmental Biology, Max-Planck Ring 9, 72076 Tübingen, Germany
- Department of Genetics, Faculty of Agriculture, Cairo University, 12613 Giza, Egypt
| | - Ata Kalirad
- Max Planck Institute for Developmental Biology, Max-Planck Ring 9, 72076 Tübingen, Germany
| | - Stefano Giaimo
- Max Planck Institute for Evolutionary Biology, August-Thienemann-Str. 2, 24306 Plön, Germany
| | - Gabi Eberhardt
- Max Planck Institute for Developmental Biology, Max-Planck Ring 9, 72076 Tübingen, Germany
| | - Hanh Witte
- Max Planck Institute for Developmental Biology, Max-Planck Ring 9, 72076 Tübingen, Germany
| | - Martin Wilecki
- Max Planck Institute for Developmental Biology, Max-Planck Ring 9, 72076 Tübingen, Germany
| | - Christian Rödelsperger
- Max Planck Institute for Developmental Biology, Max-Planck Ring 9, 72076 Tübingen, Germany
| | - Arne Traulsen
- Max Planck Institute for Evolutionary Biology, August-Thienemann-Str. 2, 24306 Plön, Germany
| | - Ralf J Sommer
- Max Planck Institute for Developmental Biology, Max-Planck Ring 9, 72076 Tübingen, Germany.
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Abstract
For the first 25 years after the landmark 1974 paper that launched the field, most C. elegans biologists were content to think of their subjects as solitary creatures. C. elegans presented no shortage of fascinating biological problems, but some of the features that led Brenner to settle on this species-in particular, its free-living, self-fertilizing lifestyle-also seemed to reduce its potential for interesting social behavior. That perspective soon changed, with the last two decades bringing remarkable progress in identifying and understanding the complex interactions between worms. The growing appreciation that C. elegans behavior can only be meaningfully understood in the context of its ecology and evolution ensures that the coming years will see similarly exciting progress.
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Affiliation(s)
- Douglas S Portman
- Departments of Biomedical Genetics, Neuroscience, and Biology, Del Monte Institute for Neuroscience, University of Rochester, Rochester, NY, USA
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