Daphnia magna responses to fish kairomone and chlorpromazine exposures

In freshwater zooplankton diel vertical migration (DVM) is a widespread predator-avoidance behavior that is induced by kairomones released from fish. Thereby zooplankton reduces predation by fish by staying in deep and dark colder strata during daytime and migrating into warmer layers during night, and thus experiences diel alterations in temperature. Constantly lower temperatures have been shown to increase the relative abundance of polyunsaturated fatty acids (PUFAs) in Daphnia sp. Furthermore, a low dietary supply of the ω3-PUFA eicosapentaenoic acid (EPA) has been shown to limit the induction of DVM in Daphnia magna and the performance of D. magna under fluctuating temperatures, as experienced during DVM. In nature DVM of D. magna in response to fish is accompanied by the presence of fish-borne kairomone and diel fluctuations of depth dependent-parameters like temperature, food, and oxygen supply. Here we investigated the effect of factors, which are differing between Daphnia that perform DVM and those which do not. We selected to examine the effect of changing temperature and light conditions and of the presence/absence of fish kairomones on D. magna. For this purpose, we conducted a full factorial experimental design in which we grew D. magna under constantly warm temperatures in a diel light-dark regime or under alternating temperatures in darkness crossed with the presence or absence of fish kairomones. We analyzed the fatty acid composition of mature animals and of their offspring in each treatment. Simulation of the light and temperature regime of migrating animals in presence of the fish kairomone resulted in an increased relative allocation of the ω3-PUFA EPA, from adult animals to their offspring, manifesting as decreased EPA concentrations in mothers and increased EPA concentrations in their offspring in response to simulated DVM (mothers). Additionally, EPA concentrations in the offspring were affected by the interaction of simulated DVM and the fish cue. The presence of the fish kairomone alone increased the EPA concentration in the offspring, that was not experiencing simulated DVM. These findings lead to the conclusion that the temperature and light regime associated with DVM alone, as well as in combination with the DVM-inducing fish kairomones, alter the allocation of fatty acids to the offspring in a manner, which is beneficial for the offspring under the decreased average temperatures, which migrating animals are exposed to. A low dietary supply of ω3-PUFAs may constrain D. magna’s amplitude of DVM, but our results suggest that the next generation of animals may be capable of regaining the full DVM amplitude due to the effect of the fish kairomone and the experienced temperature fluctuations (and darkness) on tissue fatty acid composition. These findings suggest that fatty acid limitation in DVM performing Daphnia may be more severe for the maternal than for the offspring generation.

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Transcriptional response to kairomone exposure in Daphnia magna: A candidate gene approach

10.21203/rs.2.20016/v1 ◽

2020 ◽

Author(s):

Murat Telli ◽

Donna M. Gordon ◽

Ercan Selçuk Ünlü

Keyword(s):

Daphnia Magna ◽

Time Course ◽

Biological Activities ◽

Predatory Fish ◽

Candidate Gene Approach ◽

Late Time ◽

Mrna Transcript ◽

Transcript Levels ◽

Fish Kairomone ◽

Ideal System

Abstract Background: Daphnia (Brachiopoda, Cladocera) is a well-studied model organism providing unparalleled opportunity to test epigenetic regulation of predator avoidance mechanisms in aquatic ecosystems. The discovery of regulatory functions for microRNA molecules and recently described miRNA profiles of Daphnia make it an ideal system to probe for posttranslational regulatory mechanisms mediated by kairomone released by predatory fish. However, despite a number of studies that focused on mRNA transcript level differences, no miRNA studies associated with kairomone exposure have been reported. Results: Exposing D. magna to fish kairomone from birth to the first reproduction was found to result in the differential expression of the four miRNAs tested: miR-7, miR-34, miR-317, and miR-375. Normalized transcript levels for each miRNA were found to vary across the exposure period with no clear conserved pattern of expression despite functional target analyses by GO, COG and KEGG indicating that predicted miRNA target genes are likely involved in related biological activities. Analysis of six mRNA transcripts (Hsp70, Hsp90, actin, AKT, GYS and IGFR), identified in previous studies as kairomone-mediated genes in Daphnia magna, were also carried out. Similar to that obtained for miRNAs, the mRNA transcript levels showed varying degrees of temporal regulation across the exposure time course with the two heat shock transcripts exhibiting elevated levels at early and late time points of kairomone exposure while the AKT, GYS, and IGFR transcripts had an general decrease in expression during the first 96 hours. Conclusions: Differential mRNA expression data supports the premise of an ecological trade-off between the cost of general biological processes and that of survival under long-term kairomone stress. Transcript levels for the four miRNAs tested were found to vary across developmental time with kairomone exposure which suggests that they may have a role in regulating morphological, behavioral or physiological responses by altering target gene expression. These studies lay the foundation for future work aimed at linking miRNAs and their target transcripts to changes in the signaling events that govern Daphnia response to kairomone specific stress.

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Transcriptional response and functional target analyses of miRNA and mRNA to planktivorous fish kairomone exposure in Daphnia magna

Fundamental and Applied Limnology / Archiv für Hydrobiologie ◽

10.1127/fal/2021/1386 ◽

2021 ◽

Author(s):

Murat Telli ◽

Donna M. Gordon ◽

Ercan Selçuk Ünlü

Keyword(s):

Daphnia Magna ◽

Transcriptional Response ◽

Planktivorous Fish ◽

Fish Kairomone

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Enhanced sensitivity to an insecticide carbaryl in Daphnia magna mediated by fish kairomone

Limnology ◽

10.1007/s10201-019-00572-4 ◽

2019 ◽

Vol 20 (2) ◽

pp. 137-141 ◽

Cited By ~ 1

Author(s):

Yusuke Oda ◽

Kazuya Sato ◽

Takayuki Hanazato ◽

Kwang-Hyeon Chang ◽

Masaki Sakamoto

Keyword(s):

Daphnia Magna ◽

Enhanced Sensitivity ◽

Fish Kairomone

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Membrane-bound vesicles associated with the microvilli in the midgut of the freshwater microcrustacean, Daphnia magna

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100076135 ◽

1983 ◽

Vol 41 ◽

pp. 480-481

Author(s):

Patricia L. Jansma

Keyword(s):

Daphnia Magna ◽

Intestinal Epithelial Cells ◽

Uranyl Acetate ◽

Intestinal Epithelial ◽

Chlamydomonas Reinhardii ◽

Thin Sections ◽

Saturated Water ◽

Cacodylate Buffer ◽

Membrane Bound ◽

Ethanol Series

The presence of the membrane bound vesicles or blebs on the intestinal epithelial cells has been demonstrated in a variety of vertebrates such as chicks, piglets, hamsters, and humans. The only invertebrates shown to have these microvillar blebs are two species of f1ies. While investigating the digestive processes of the freshwater microcrustacean, Daphnia magna, the presence of these microvillar blebs was noticed.Daphnia magna fed in a suspension of axenically grown green alga, Chlamydomonas reinhardii for one hour were narcotized with CO2 saturated water. The intestinal tracts were excised in 2% glutaraldehyde in 0.2 M cacodyl ate buffer and then placed in fresh 2% glutaraldehyde for one hour. After rinsing in 0.1 M cacodylate buffer, the sample was postfixed in 2% OsO4, dehydrated with a graded ethanol series, infiltrated and embedded with Epon-Araldite. Thin sections were stained with uranyl acetate and Reynolds lead citrate before viewing with the Philips EM 200.

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Computer Reconstruction of the Cellular Architecture of the Daphnia Magna Optic Ganglion

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100115043 ◽

1975 ◽

Vol 33 ◽

pp. 284-285

Author(s):

E. R. Macagno ◽

C. Levinthal

Keyword(s):

Daphnia Magna ◽

Genetic Background ◽

Compound Eye ◽

Synaptic Connectivity ◽

Serial Sections ◽

Cross Sectional ◽

Small Crustacean ◽

Optic Ganglion ◽

Structural Invariance ◽

High Degree

The optic ganglion of Daphnia Magna, a small crustacean that reproduces parthenogenetically contains about three hundred neurons: 110 neurons in the Lamina or anterior region and about 190 neurons in the Medulla or posterior region. The ganglion lies in the midplane of the organism and shows a high degree of left-right symmetry in its structures. The Lamina neurons form the first projection of the visual output from 176 retinula cells in the compound eye. In order to answer questions about structural invariance under constant genetic background, we have begun to reconstruct in detail the morphology and synaptic connectivity of various neurons in this ganglion from electron micrographs of serial sections (1). The ganglion is sectioned in a dorso-ventra1 direction so as to minimize the cross-sectional area photographed in each section. This area is about 60 μm x 120 μm, and hence most of the ganglion fit in a single 70 mm micrograph at the lowest magnification (685x) available on our Zeiss EM9-S.

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