Dopamine is a key regulator in the signalling pathway underlying predator-induced defences in
            Daphnia

The waterflea Daphnia is a model to investigate the genetic basis of phenotypic plasticity resulting from one differentially expressed genome. Daphnia develops adaptive phenotypes (e.g. morphological defences) thwarting predators, based on chemical predator cue perception. To understand the genomic basis of phenotypic plasticity, the description of the precedent cellular and neuronal mechanisms is fundamental. However, key regulators remain unknown. All neuronal and endocrine stimulants were able to modulate but not induce defences, indicating a pathway of interlinked steps. A candidate able to link neuronal with endocrine responses is the multi-functional amine dopamine. We here tested its involvement in trait formation in Daphnia pulex and Daphnia longicephala using an induction assay composed of predator cues combined with dopaminergic and cholinergic stimulants. The mere application of both stimulants was sufficient to induce morphological defences. We determined dopamine localization in cells found in close association with the defensive trait. These cells serve as centres controlling divergent morphologies. As a mitogen and sclerotization agent, we anticipate that dopamine is involved in proliferation and structural formation of morphological defences. Furthermore, dopamine pathways appear to be interconnected with endocrine pathways, and control juvenile hormone and ecdysone levels. In conclusion, dopamine is suggested as a key regulator of phenotypic plasticity.

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Genetic basis of phenotypic plasticity and genotype x environment interaction in a multi-parental population

10.1101/2020.02.07.938456 ◽

2020 ◽

Author(s):

Isidore Diouf ◽

Laurent Derivot ◽

Shai Koussevitzky ◽

Yolande Carretero ◽

Frédérique Bitton ◽

...

Keyword(s):

Phenotypic Plasticity ◽

Genetic Architecture ◽

Genetic Basis ◽

Linear Models ◽

Global Climate ◽

Functional Characterization ◽

Genotype X Environment Interaction ◽

Environment Interaction ◽

Multiple Traits ◽

Genotype X Environment

AbstractDeciphering the genetic basis of phenotypic plasticity and genotype x environment interaction (GxE) is of primary importance for plant breeding in the context of global climate change. Tomato is a widely cultivated crop that can grow in different geographical habitats and which evinces a great capacity of expressing phenotypic plasticity. We used a multi-parental advanced generation intercross (MAGIC) tomato population to explore GxE and plasticity for multiple traits measured in a multi-environment trial (MET) design comprising optimal cultural conditions and water deficit, salinity and heat stress over 12 environments. Substantial GxE was observed for all the traits measured. Different plasticity parameters were estimated through the Finlay-Wilkinson and factorial regression models and used together with the genotypic means for quantitative trait loci (QTL) mapping analyses. Mixed linear models were further used to investigate the presence of interactive QTLs (QEI). The results highlighted a complex genetic architecture of tomato plasticity and GxE. Candidate genes that might be involved in the occurrence of GxE were proposed, paving the way for functional characterization of stress response genes in tomato and breeding for climate-adapted crop.HighlightThe genetic architecture of tomato response to several abiotic stresses is deciphered. QTL for plasticity and QTL x Environment were identified in a highly recombinant MAGIC population.

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Experimental Evolution Reveals a Genetic Basis for Membrane-Associated Virus Release

Molecular Biology and Evolution ◽

10.1093/molbev/msaa208 ◽

2020 ◽

Author(s):

Juan-Vicente Bou ◽

Rafael Sanjuán

Keyword(s):

Experimental Evolution ◽

Genetic Basis ◽

Close Association ◽

Site Directed Mutagenesis ◽

Full Genome ◽

Virus Release ◽

Viral Shedding ◽

Free Virion ◽

Viral Particles ◽

Evolution Experiment

Abstract Many animal viruses replicate and are released from cells in close association to membranes. However, whether this is a passive process or is controlled by the virus remains poorly understood. Importantly, the genetic basis and evolvability of membrane-associated viral shedding have not been investigated. To address this, we performed a directed evolution experiment using coxsackievirus B3, a model enterovirus, in which we repeatedly selected the free-virion or the fast-sedimenting membrane-associated viral subpopulations. The virus responded to this selection regime by reproducibly fixing a series of mutations that altered the extent of membrane-associated viral shedding, as revealed by full-genome ultra-deep sequencing. Specifically, using site-directed mutagenesis, we showed that substitution N63H in the viral capsid protein VP3 reduced the ratio of membrane-associated to free viral particles by 2 orders of magnitude. These findings open new avenues for understanding the mechanisms and implications of membrane-associated viral transmission.

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Predator-induced phenotypic plasticity in Daphnia pulex: Life history and morphological responses to Notonecta and Chaoborus

Limnology and Oceanography ◽

10.4319/lo.1993.38.5.0986 ◽

1993 ◽

Vol 38 (5) ◽

pp. 986-996 ◽

Cited By ~ 47

Author(s):

A. Ross Black

Keyword(s):

Life History ◽

Phenotypic Plasticity ◽

Daphnia Pulex ◽

Morphological Responses

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Interaction between competitors and predators and its effects on morphological and behavioural defences in Scinax nasicus tadpoles

Behaviour ◽

10.1163/1568539x-00003085 ◽

2013 ◽

Vol 150 (8) ◽

pp. 921-937 ◽

Cited By ~ 3

Author(s):

Valeria I. Gómez ◽

Arturo I. Kehr

Keyword(s):

Growth Rate ◽

Experimental Design ◽

Growth And Development ◽

Chemical Cues ◽

Development Rate ◽

Larval Morphology ◽

Induced Defences ◽

Morphological Defences ◽

Growth Development ◽

Determinant Factor

Predation affects the behaviour of organisms, and the number of conspecifics can influence the perception of predation risk. Two main types of traits, morphological and behavioural, are involved in the induced defences of many organisms. Here, we examined the influence of chemical cues of the predators Belostoma elongatum (Hemiptera, Belostomatidae) and Moenkhausia dichroura (Characiformes, Characidae) on the morphology, growth, development and activity of Scinax nasicus larvae. Our main goal was to determine whether the investment in morphological or behavioural defences varied according to the number of conspecifics and to the chemical cues of predators. To this end, we performed two experiments under microcosm conditions. In experiment 1, we determined morphological defences in tadpoles by analysing changes in morphology, growth rate and development rate, whereas in experiment 2, we determined behavioural defences by analysing changes in the activity of tadpoles. The experimental design consisted of two tadpole densities, with and without chemical cues of predators. We found that: (1) larval morphology, growth and development were significantly affected by density; (2) the chemical cues of the predators did not influence the morphology, growth or development of tadpoles; (3) tadpoles at high densities were more active than those at low densities; (4) tadpoles decreased the activity in the presence of chemical cues of M. dichroura; and (5) tadpoles increased the activity in the presence of chemical cues of B. elongatum. Our results suggest that density is a determinant factor of tadpole morphology of and that Scinax nasicus larvae respond to predators with behavioural defences, which vary according to the type of predator.

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Environmentally controlled phenotypic plasticity of morphology and polypeptide expression in two populations of Daphnia pulex (Crustacea: cladocera)

Oecologia ◽

10.1007/bf00379879 ◽

1984 ◽

Vol 63 (2) ◽

pp. 207-214 ◽

Cited By ~ 3

Author(s):

Lester W. Lee

Keyword(s):

Phenotypic Plasticity ◽

Daphnia Pulex ◽

Two Populations

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Modulation of Type IV pili phenotypic plasticity through a novel Chaperone-Usher system in Synechocystis sp.

10.1101/130278 ◽

2017 ◽

Cited By ~ 3

Author(s):

Anchal Chandra ◽

Lydia-Maria Joubert ◽

Devaki Bhaya

Keyword(s):

Phenotypic Plasticity ◽

Extreme Environments ◽

Type Iv Pili ◽

Structural Modifications ◽

Carbon And Nitrogen ◽

Type Iv ◽

Phenotypic Transition ◽

And Control ◽

Camp Levels ◽

Synechocystis Sp

AbstractControlling the transition from a multicellular motile state to a sessile biofilm is an important eco-physiological decision for most prokaryotes, including cyanobacteria. Photosynthetic and bio geochemically significant cyanobacterium Synechocystis sp. PCC6803 (Syn6803) uses Type IV pili (TFP) for surface-associated motility and light-directed phototaxis. We report the identification of a novel Chaperone-Usher (CU) system in Syn6803 that regulate secretion of minor pilins as a means of stabilizing TFP morphology. These secreted minor-pilins aid in modifying TFP morphology to suit the adhesion state by forming cell to surface contacts when motility is not required. This morphotype is structurally distinct from TFP assembled during motile phase. We further demonstrate by examining mutants lacking either the CU system or the minor-pilins, which produce aberrant TFP, that are morphologically and functionally distinct from wild-type (WT). Thus, here we report that in Syn6803, CU system work independent of TFP biogenesis machinery unlike reported for other pathogenic bacterial systems and contributes to provide multifunctional plasticity to TFP. cAMP levels play an important role in controlling this switch. This phenotypic plasticity exhibited by the TFP, in response to cAMP levels would allow cells and cellular communities to adapt to rapidly fluctuating environments by dynamically transitioning between motile and sessile states.Significance of this workHow cyanobacterial communities cope with fluctuating or extreme environments is crucial in understanding their role in global carbon and nitrogen cycles. This work addresses the key question: how do cyanobacteria modulate external appendages, called Type IV pili, to effectively switch between motile and sessile biofilm states? We demonstrate that cells transition between forming strong cell-surface interactions indispensable for biofilm formation to forming cell-cell interactions that allow for coordinated movement crucial for social motility by functional/ structural modification of same TFP appendage. The second messenger, cAMP and a Chaperone-Usher secretion are indispensible to achieve these structural modifications of TFP and control the complex phenotypic transition. We have uncovered a strategy that Syn6803 has evolved to deal with molecular decision-making under uncertainty, which we call phenotypic plasticity. Here we demonstrate how a single motility appendage can be structurally modified to attain two antagonistic functions in order to meet the fluctuating environmental demands.

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Phenotypic plasticity more essential to maintaining variation in host-attachment behaviour than evolutionary trade-offs in a facultatively parasitic mite

Parasitology ◽

10.1017/s0031182019000507 ◽

2019 ◽

Vol 146 (10) ◽

pp. 1289-1295 ◽

Cited By ~ 2

Author(s):

Emily S. Durkin ◽

Lien T. Luong

Keyword(s):

Phenotypic Plasticity ◽

Natural Populations ◽

Fitness Advantage ◽

Trade Offs ◽

Parasitic Mite ◽

Facultative Parasite ◽

Parasitic Activity ◽

Fitness Benefits ◽

And Control ◽

Attachment Behaviour

AbstractA prevailing hypothesis for the evolution of parasitism posits that the fitness benefits gained from parasitic activity results in selection for and fixation of parasitic strategies. Despite the potential fitness advantage of parasitism, facultative parasites continue to exhibit genetic variation in parasitic behaviour in nature. We hypothesized that evolutionary trade-offs associated with parasitic host-attachment behaviour maintain natural variation observed in attachment behaviour. In this study, we used replicate lines of a facultatively parasitic mite, previously selected for increased host-attachment behaviour to test whether increased attachment trades off with mite fecundity and longevity, as well as the phenotypic plasticity of attachment. We also tested for potential correlated changes in mite morphology. To test for context-dependent trade-offs, mite fecundity and longevity were assayed in the presence or absence of a host. Our results show that selected and control mites exhibited similar fecundities, longevities, attachment plasticities and morphologies, which did not provide evidence for life history trade-offs associated with increased attachment. Surprisingly, phenotypic plasticity in attachment was maintained despite directional selection on the trait, which suggests that phenotypic plasticity likely plays an important role in maintaining attachment variation in natural populations of this facultative parasite.

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Methodology for Inoculating Sweetpotato Virus Disease: Discovery of Tip Dieback, and Plant Recovery and Reversion in Different Clones

Plant Disease ◽

10.1094/pdis-12-11-1072-re ◽

2013 ◽

Vol 97 (1) ◽

pp. 30-36 ◽

Cited By ~ 6

Author(s):

R. O. M. Mwanga ◽

G. C. Yencho ◽

R. W. Gibson ◽

J. W. Moyer

Keyword(s):

East Africa ◽

Ipomoea Batatas ◽

Genetic Basis ◽

Virus Disease ◽

Rapid Screening ◽

Viral Diseases ◽

Hypersensitivity Response ◽

Plant Recovery ◽

Grafting Technique ◽

And Control

Evaluating sweetpotato (Ipomoea batatas) genotypes for resistance to sweetpotato virus disease (SPVD) has been slow and inefficient. Ipomoea setosa plants, normally used as the source of scions for graft-infecting sweetpotatoes with viral diseases, are often severely stunted and their mortality is 10 to 30% when infected with SPVD, making them unsuitable as scions. Tanzania, a landrace of I. batatas widely grown in East Africa, was found to be a superior host for maintaining and increasing SPVD inoculum (scions) for mass grafting. Modifications to a cleft-grafting technique also increased survival of grafted SPVD-affected scions from 5 to 100%. These modifications, coupled with an efficient SPVD scoring technique, allowed rapid screening of large sweetpotato populations for SPVD resistance. Plant recovery from SPVD is reported here as a component of SPVD resistance. Differences in recovery from SPVD were detected among progenies, indicating its genetic basis. Plant tip dieback, a hypersensitivity response, was observed only in families with cv. Wagabolige as a parent. These findings may open up new opportunities for improved understanding and control of this devastating disease.

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Demographic costs of Chaoborus-induced defences in Daphnia pulex: a sensitivity analysis

Oecologia ◽

10.1007/bf00323778 ◽

1991 ◽

Vol 87 (1) ◽

pp. 43-50 ◽

Cited By ~ 34

Author(s):

Mari Walls ◽

Hal Caswell ◽

Matti Ketola

Keyword(s):

Sensitivity Analysis ◽

Daphnia Pulex ◽

Induced Defences

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Experimental Assessment of the Influence of Gull-Billed Terns on Nest Site Choice of Black Skimmers

The Condor ◽

10.1093/condor/104.1.174 ◽

2002 ◽

Vol 104 (1) ◽

pp. 174-177

Author(s):

Sandra M. Pius ◽

Paul L. Leberg

Keyword(s):

Nest Site ◽

Close Association ◽

Habitat Partitioning ◽

Mixed Species ◽

Experimental Assessment ◽

Nest Site Choice ◽

Species Specific ◽

And Control

Abstract The hypothesis that members of one species might benefit from nesting with heterospecifics has been proposed to explain the existence of mixed-species breeding colonies. Black Skimmers (Rhynchops niger) usually nest in close association with one of several tern species (Sterna spp.); benefits of this association might lead skimmers to use different nesting substrates than terns, thus facilitating coexistence. Manipulating availability of substrates, we found that skimmers exclusively nested on substrates normally occupied by terns, indicating that habitat partitioning detected in previous studies was not a result of species-specific preferences. Using arrays of tern, skimmer, and control decoys, we found that skimmers nested more often with conspecifics than with terns. Our results suggest that the tendency of skimmers to nest in association with terns, but on different substrates, may be more influenced by nesting sequence than from a preference to nest near terns. Estimación Experimental de la Influencia de Sterna nilotica sobre la Selección de Sitios de Nidificación de Rhynchops niger Resumen. La hipótesis que sugiere que miembros de una especie podrían recibir beneficios al anidar con organismos de diferentes especies ha sido propuesta para explicar la tendencia de algunas aves coloniales a formar grupos interespecíficos de nidificación. Individuos de Rhynchops niger generalmente anidan en asociación con alguna de las diferentes especies de golondrinas marinas (Sterna spp.). Los beneficios de esta asociación podrían hacer que R. niger utilice diferentes substratos para anidar que aquellos utilizados por las golondrinas lo cual facilitaría su coexistencia. Al manipular la disponibilidad de los substratos, se encontró que R. niger anida en substratos ocupados normalmente por golondrinas; indicando que la repartición del hábitat observada en estudios previos no es el resultado de preferencias especie-específicas. Encontramos que los rayadores anidaron más comúnmente con miembros de su misma especie que con golondrinas cuando se les dio la opción de elegir entre grupos al utilizar líneas de señuelos. Nuestros resultados sugieren que la tendencia de R. niger a anidar en asociación con golondrinas en diferentes substratos podría estar más influenciada por la secuencia de nidificación, que por la preferencia de anidar en proximidad a las golondrinas marinas.

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