Life-History Traits of the Model Organism Pristionchus pacificus Recorded Using the Hanging Drop Method: Comparison with Caenorhabditis elegans

Gilarte, Patricia; Kreuzinger‐Janik, Bianca; Majdi, Nabil; Traunspurger, Walter

doi:10.1371/journal.pone.0134105

Cited by 12 publications

(7 citation statements)

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“…8). 177 Importantly, this is still within the egg-laying period 32 , potentially contributing to increased 178 fitness. Nevertheless, these assumptions are subject to several difficult-to-measure factors that 179 could both positively and negatively affect K, such as the consumption rate of other nematode 180 .…”

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confidence: 99%

Adult influence on juvenile phenotypes by stage-specific pheromone production

Werner

Claaßen

Renahan

et al. 2018

Preprint

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1Animals and plants can predict decreasing food supplies by recognition of population density, 2 and respond by adjusting behavioral and morphological traits. Population density in nematodes 3 is detected through pheromones, influencing dormant (dauer) stage entry, and in some lineages 4 alternative mouth-form decision (bacterivorous vs. predatory). Whether age is a relevant 5 parameter in recognizing population density is not well understood. Here, we utilized the mouth-6 form plasticity of the model nematode Pristionchus pacificus and developmental pheromone 7 profiling to study potential parent:progeny communication. Surprisingly, we observed adult-8 specific production of molecules that induce the predatory morph, even though adult mouth 9 forms are no longer plastic. We introduce a novel dye-based method to differentiate populations 10 in mixed-generation cultures, and found adults, but not peers, influence developing juvenile 11 mouth forms. Finally, we applied a logistic growth model that demonstrates adults both lower 12 the population carrying capacity and decrease the time until resource depletion. In the 13 necromenic life cycle of P. pacificus, we view mouth-form plasticity as an alternative 'Malthusian 14 escape' strategy to dauer that responds to age-specific population densities. The copyright holder for this preprint (which was not . http://dx.doi.org/10.1101/291591 doi: bioRxiv preprint first posted online Mar. 29, 2018; Population density is an important ecological parameter that correlates with increased 26 competition for resources 1 . In addition to density-dependent selection 2 , which operates on 27 evolutionary time scales, some organisms can respond dynamically to population density by 28 phenotypic plasticity. For example, plants can sense crowding by detecting the ratio of red 29 (chlorophyll absorbing) to far red (non-absorbing) light, and respond by various shade-30 avoidance strategies including higher shoots 3 . Locusts undergo solitary to swarm (i.e. 31 gregarious) transition, and aphids can develop wings, both as a result of increased physical 32 mechanosensory contact [4][5][6] . Intriguingly, population density can also have transgenerational 33 effects. For example, adult crowding of the desert locust Schistocerca gregaria 7,8 and migratory 34 locust Locusta migratoria 9 also influences the egg size, number, and morphology of their 35 progeny, and high population densities of red squirrels elicit hormonal regulation in mothers to 36 influence faster developing offspring 10 . Nevertheless, while incorporating age into population 37 structures has significantly advanced density-dependent selection theory 11 , surprisingly little 38age-specific refinement has been incorporated into models of phenotypic plasticity, especially at 39 the mechanistic level. This is partly due to the competing challenges of (1) studying population 40 ecology in the laboratory, and (2) the paucity of laboratory model organisms that are suitable for 41 ecological studies. The model nematode ...

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confidence: 99%

Adult influence on juvenile phenotypes by stage-specific pheromone production

Werner

Claaßen

Renahan

et al. 2018

Preprint

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“…The pre-hatch development timeline was initially observed using a hanging drop method with modifications [24]. Single eggs were added to 6 μl of either water or a hatching stimulant in a concave well microscope slide and covered with a coverslip.…”

Section: Methodsmentioning

confidence: 99%

Embryogenesis in the parasitic nematode Heterodera glycines is independent of host-derived hatching stimulation

et al. 2017

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BackgroundMany parasites regulate their development to synchronize their life cycle with a compatible host. The parasitic nematode Heterodera glycines displays incomplete host-mediated hatching behavior wherein some H. glycines individuals hatch only in the presence of a host-derived cue while others hatch in water alone. Furthermore, H. glycines shows variable hatching behavior based on oviposition location. The mechanisms regulating this hatching variability are unknown. In this study, we established a detailed timeline of the H. glycines pre-hatch development from early embryogenesis to the pre-hatched J2. These descriptive data were then used to test hypotheses regarding the effect of host stimulus and oviposition location on pre-hatch development.ResultsWe found that H. glycines develops from a single-cell egg to a fully formed J2 in approximately 172 hours. The stylet-based mouthpart, which is used to pierce the eggshell during hatching, is not completely formed until late in pre-hatch J2 development and is preceded by the formation of stylet protractor muscles. We also found that the primary motor nervous system of H. glycines did not complete development until late in pre-hatch J2 development. These data suggest possible structural requirements for H. glycines hatching. As expected, exposure of H. glycines eggs to host-derived cues increased the percentage of nematodes that hatched. However, exposure to hatching cues did not affect pre-hatch development. Similarly, we found no obvious differences in the pre-hatch developmental timeline between eggs laid in an egg sac or retained within the mother.ConclusionsThe pattern of early embryonic development in H. glycines was very similar to that recently described in the related parasitic nematode Meloidogyne incognita. However, the speed of H. glycines pre-hatch development was approximately three times faster than reported for M. incognita. Our results suggest that hatching stimulants do not affect embryogenesis itself but only influence the hatching decision once J2 development is complete. Similarly, the oviposition location does not alter the rate of embryogenesis. These results provide insight into the primary survival mechanism for this important parasite.

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“…The first of these traits, lifetime fecundity, was chosen based on its use as a standard life‐history measure (Gilarte et al. ) and its demonstrated ability to detect fitness differences on alternative diets in P. pacificus (Rae et al. ; Serobyan et al.…”

Section: Methodsmentioning

confidence: 99%

“…Specifically, we recorded brood sizes and growth rates for the wild-type strain and all single, double, and triple mutants. The first of these traits, lifetime fecundity, was chosen based on its use as a standard life-history measure (Gilarte et al 2015) and its demonstrated ability to detect fitness differences on alternative diets in P. pacificus (Rae et al 2008;Serobyan et al 2014). We measured the second trait, growth rate, because of the previous detection of differences in rates between the two mouth-morphs on a similar diet, albeit with a finer time-course than what we employ here (Serobyan et al 2013).…”

Section: Phenotypic Assaysmentioning

confidence: 99%

Specialization of a polyphenism switch gene following serial duplications inPristionchusnematodes

Ragsdale

Ivers

2016

Evolution

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Polyphenism is an extreme manifestation of developmental plasticity, requiring distinct developmental programs and the addition of a switch mechanism. Because the genetic basis of polyphenism switches has only begun to be understood, how their mechanisms arise is unclear. In the nematode Pristionchus pacificus, which has a mouthpart polyphenism specialized for alternative diets, a gene (eud-1) executing the polyphenism switch was recently identified as the product of lineage-specific duplications. Here, we infer the role of gene duplications in producing a switch gene. Using reverse genetics and population genetic analyses, we examine evidence for competing scenarios of degeneration and complementation, neutral evolution, and functional specialization. Of the daughter genes, eud-1 alone has assumed switch-like regulation of the mouth polyphenism. Measurements of life-history traits in single, double, and triple sulfatase mutants did not, given a benign environment, identify alternative or complementary roles for eud-1 paralogs. Although possible roles are still unknown, selection analyses of the sister species and 104 natural isolates of P. pacificus detected purifying selection on the genes, suggesting their functionality by their fixation and evolutionary maintenance. Our approach shows the tractability of reverse genetics in a nontraditional model system to study evolution by gene duplication.

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Life-History Traits of the Model Organism Pristionchus pacificus Recorded Using the Hanging Drop Method: Comparison with Caenorhabditis elegans

Cited by 12 publications

References 48 publications

Adult influence on juvenile phenotypes by stage-specific pheromone production

Adult influence on juvenile phenotypes by stage-specific pheromone production

Embryogenesis in the parasitic nematode Heterodera glycines is independent of host-derived hatching stimulation

Specialization of a polyphenism switch gene following serial duplications inPristionchusnematodes

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