Gene expression profiling of three different stressors in the water flea Daphnia magna

Abstract

Microarrays are an ideal tool to screen for differences in gene expression of thousands of genes simultaneously. However, often commercial arrays are not available. In this study, we performed microarray analyses to evaluate patterns of gene transcription following exposure to two natural and one anthropogenic stressor. cDNA microarrays compiled of three life stage specific and three stressor-specific EST libraries, yielding 1734 different EST sequences, were used. We exposed juveniles of the water flea Daphnia magna for 48, 96 and 144 h to three stressors known to exert strong selection in natural populations of this species i.e. a sublethal concentration of the pesticide carbaryl, infective spores of the endoparasite Pasteuria ramosa, and fish predation risk mimicked by exposure to fish kairomones. A total of 148 gene fragments were differentially expressed compared to the control. Based on a PCA, the exposure treatments were separated into two main groups based on the extent of the transcriptional response: a low and a high (144 h of fish or carbaryl exposure and 96 h of parasite exposure) stress group. Firstly, we observed a general stress-related transcriptional expression profile independent of the treatment characterized by repression of transcripts involved in transcription, translation, signal transduction and energy metabolism. Secondly, we observed treatment-specific responses including signs of migration to deeper water layers in response to fish predation, structural challenge of the cuticle in response to carbaryl exposure, and disturbance of the ATP production in parasite exposure. A third important conclusion is that transcription expression patterns exhibit stress-specific changes over time. Parasite exposure shows the most differentially expressed gene fragments after 96 h. The peak of differentially expressed transcripts came only after 144 h of fish exposure, while carbaryl exposure induced a more stable number of differently expressed gene fragments over time.

Temporal dynamics of neurogenomic plasticity in response to social interactions in male threespined sticklebacks

“…These changes are coordinated at the neural level, but social interactions also elicit transcriptional changes within the brains of behaving animals [1]. For example, genome-wide transcription studies show that roughly ~10% of the genome responds to a mating opportunity [2–7], predation risk [8–10], or a territorial challenge [11–13]. …”

Proteomic data reveals a physiological basis for costs and benefits associated with thermal acclimation

“…through physiological adaptation within the lifetime of an individual, is one alternative way to cope with extreme and fluctuating temperatures (Angiletta, 2009;Chown and Terblanche, 2006;Hoffmann and Parsons, 1997;Hoffmann et al, 2003). Studies on ectotherms investigating thermal acclimation and the physiological changes induced in response to acclimation typically do so by exposing adult organisms to short-term cold or hot temperatures and subsequently studying the consequences on thermal and molecular phenotypes (Overgaard et al, 2005;Sørensen et al, 2005;Malmendal et al, 2006;Teranishi and Stillman, 2007;Nota et al, 2010;Teets et al, 2012;Colinet et al, 2013;Jansen et al, 2013;Wei et al, 2015). Such studies have provided novel insights into the molecular aspects of acclimation responses and have added important components to our knowledge on associations between the genotype, the molecular phenotype and thermal resistance.…”

Metabolic and functional characterization of effects of developmental temperature in Drosophila melanogaster

“…Laboratory studies on ectotherms investigating acclimation and the physiological changes induced during acclimation typically do so by exposing test organisms to short-term cold or hot temperatures and subsequently studying the consequences on thermal resistance and molecular phenotypes (11, 26, 39, 41, 44, 62, 64, 65, but see 7, 36). Such studies have provided novel insights into the molecular aspects of the acclimation response and have contributed to our knowledge on associations between the genotype and the phenotype.…”