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Obesogens beyond Vertebrates: Lipid Perturbation by Tributyltin in the Crustacean Daphnia magna.

Jordão R, Casas J, Fabrias G, Campos B, Piña B, Lemos MF, Soares AM, Tauler R, Barata C - Environ. Health Perspect. (2015)

Bottom Line: The analysis of obesogenic effects in invertebrates is limited by our poor knowledge of the regulatory pathways of lipid metabolism.TBT's disruptive effects translated into a lower fitness for offspring and adults.These findings indicate the presence of obesogenic effects in a nonvertebrate species.

View Article: PubMed Central - PubMed

Affiliation: Department of Environmental Chemistry, Institute of Environmental Assessment and Water Research (IDAEA), Spanish Research Council (IDAEA, CSIC), Barcelona, Spain.

ABSTRACT

Background: The analysis of obesogenic effects in invertebrates is limited by our poor knowledge of the regulatory pathways of lipid metabolism. Recent data from the crustacean Daphnia magna points to three signaling hormonal pathways related to the molting and reproductive cycles [retinoic X receptor (RXR), juvenile hormone (JH), and ecdysone] as putative targets for exogenous obesogens.

Objective: The present study addresses the disruptive effects of the model obesogen tributyltin (TBT) on the lipid homeostasis in Daphnia during the molting and reproductive cycle, its genetic control, and health consequences of its disruption.

Methods: D. magna individuals were exposed to low and high levels of TBT. Reproductive effects were assessed by Life History analysis methods. Quantitative and qualitative changes in lipid droplets during molting and the reproductive cycle were studied using Nile red staining. Lipid composition and dynamics were analyzed by ultra-performance liquid chromatography coupled to a time-of-flight mass spectrometer. Relative abundances of mRNA from different genes related to RXR, ecdysone, and JH signaling pathways were studied by qRT-PCR.

Results and conclusions: TBT disrupted the dynamics of neutral lipids, impairing the transfer of triacylglycerols to eggs and hence promoting their accumulation in adult individuals. TBT's disruptive effects translated into a lower fitness for offspring and adults. Co-regulation of gene transcripts suggests that TBT activates the ecdysone, JH, and RXR receptor signaling pathways, presumably through the already proposed interaction with RXR. These findings indicate the presence of obesogenic effects in a nonvertebrate species.

No MeSH data available.


Transcription patterns (mean ± SE; n = 5) shown by the number of mRNA copies of the eight studied genes (HR3, EcRB, Neverland, HR38, MET, SRC, Hb2, and RXR), relative to G3PDH, across the adolescent instar in females exposed to TBT L (gray triangles), TBT H (black triangles), or the carrier solvent (open circles).
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f3: Transcription patterns (mean ± SE; n = 5) shown by the number of mRNA copies of the eight studied genes (HR3, EcRB, Neverland, HR38, MET, SRC, Hb2, and RXR), relative to G3PDH, across the adolescent instar in females exposed to TBT L (gray triangles), TBT H (black triangles), or the carrier solvent (open circles).

Mentions: Gene responses. The profiles of mRNA abundance for the eight genes analyzed in this study during the molting/reproductive cycle in control females are shown in Figure 3. Levels of mRNA of RXR, SRC, EcRB, HR3, and Neverland genes varied during the instar, being highest at 0 and 48 hr, whereas HR38, Hb2, and MET levels remained relatively constant throughout the cycle. TBT treatments significantly increased transcript levels of seven of eight of these genes at least in some phases of the molting/reproductive cycle, including MET and, particularly, Hb2, which remained relatively constant in control conditions (Figure 3; for ANOVA results, see Supplemental Material, Table S5). Affected genes include markers of the ecdysone pathway (EcRB, HR3, Neverland), the juvenile hormone signaling pathway (MET, SRC), and the RXR genes.


Obesogens beyond Vertebrates: Lipid Perturbation by Tributyltin in the Crustacean Daphnia magna.

Jordão R, Casas J, Fabrias G, Campos B, Piña B, Lemos MF, Soares AM, Tauler R, Barata C - Environ. Health Perspect. (2015)

Transcription patterns (mean ± SE; n = 5) shown by the number of mRNA copies of the eight studied genes (HR3, EcRB, Neverland, HR38, MET, SRC, Hb2, and RXR), relative to G3PDH, across the adolescent instar in females exposed to TBT L (gray triangles), TBT H (black triangles), or the carrier solvent (open circles).
© Copyright Policy - public-domain
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4529017&req=5

f3: Transcription patterns (mean ± SE; n = 5) shown by the number of mRNA copies of the eight studied genes (HR3, EcRB, Neverland, HR38, MET, SRC, Hb2, and RXR), relative to G3PDH, across the adolescent instar in females exposed to TBT L (gray triangles), TBT H (black triangles), or the carrier solvent (open circles).
Mentions: Gene responses. The profiles of mRNA abundance for the eight genes analyzed in this study during the molting/reproductive cycle in control females are shown in Figure 3. Levels of mRNA of RXR, SRC, EcRB, HR3, and Neverland genes varied during the instar, being highest at 0 and 48 hr, whereas HR38, Hb2, and MET levels remained relatively constant throughout the cycle. TBT treatments significantly increased transcript levels of seven of eight of these genes at least in some phases of the molting/reproductive cycle, including MET and, particularly, Hb2, which remained relatively constant in control conditions (Figure 3; for ANOVA results, see Supplemental Material, Table S5). Affected genes include markers of the ecdysone pathway (EcRB, HR3, Neverland), the juvenile hormone signaling pathway (MET, SRC), and the RXR genes.

Bottom Line: The analysis of obesogenic effects in invertebrates is limited by our poor knowledge of the regulatory pathways of lipid metabolism.TBT's disruptive effects translated into a lower fitness for offspring and adults.These findings indicate the presence of obesogenic effects in a nonvertebrate species.

View Article: PubMed Central - PubMed

Affiliation: Department of Environmental Chemistry, Institute of Environmental Assessment and Water Research (IDAEA), Spanish Research Council (IDAEA, CSIC), Barcelona, Spain.

ABSTRACT

Background: The analysis of obesogenic effects in invertebrates is limited by our poor knowledge of the regulatory pathways of lipid metabolism. Recent data from the crustacean Daphnia magna points to three signaling hormonal pathways related to the molting and reproductive cycles [retinoic X receptor (RXR), juvenile hormone (JH), and ecdysone] as putative targets for exogenous obesogens.

Objective: The present study addresses the disruptive effects of the model obesogen tributyltin (TBT) on the lipid homeostasis in Daphnia during the molting and reproductive cycle, its genetic control, and health consequences of its disruption.

Methods: D. magna individuals were exposed to low and high levels of TBT. Reproductive effects were assessed by Life History analysis methods. Quantitative and qualitative changes in lipid droplets during molting and the reproductive cycle were studied using Nile red staining. Lipid composition and dynamics were analyzed by ultra-performance liquid chromatography coupled to a time-of-flight mass spectrometer. Relative abundances of mRNA from different genes related to RXR, ecdysone, and JH signaling pathways were studied by qRT-PCR.

Results and conclusions: TBT disrupted the dynamics of neutral lipids, impairing the transfer of triacylglycerols to eggs and hence promoting their accumulation in adult individuals. TBT's disruptive effects translated into a lower fitness for offspring and adults. Co-regulation of gene transcripts suggests that TBT activates the ecdysone, JH, and RXR receptor signaling pathways, presumably through the already proposed interaction with RXR. These findings indicate the presence of obesogenic effects in a nonvertebrate species.

No MeSH data available.