Combined Effects of Cadmium and UVB Radiation on Sea Urchin Embryos: Skeleton Impairment Parallels p38 MAPK Activation and Stress Genes Overexpression

Chem Res Toxicol. 2015 May 18;28(5):1060-9. doi: 10.1021/acs.chemrestox.5b00080. Epub 2015 Apr 21.

Abstract

Human and natural activities release many pollutants in the marine environment. The mixture of pollutants can affect many organisms concurrently. We used Paracentrotus lividus as a model to analyze the effects on signal transduction pathways and stress gene expression in embryos exposed continuously to double stress, i.e., cadmium (Cd) from fertilization and UVB at cleavage (Cd/UVB-embryos). By microscopical inspection, we evaluated embryonic morphology after 72 h of development. Tissue-specific markers were used to assess mesoderm differentiation by immunofluorescence. We analyzed p38MAPK, ERK1/2, and JNK activation by Western blot and mRNA profiles of Pl-MT, Pl-14-3-3epsilon, and Pl-jun genes by real-time quantitative polymerase chain reaction (qPCR) and the localization of their transcripts by whole mount in situ hybridization (WMISH). We found that the Cd/UVB combined exposure induced morphological malformations in 76% of pluteus embryos, mainly affecting the development of the skeleton, including the normal branching of skeletal roads. In Cd/UVB-embryos, p38MAPK was activated 1 h after UVB exposure and a remarkable overexpression of the Pl-MT, Pl-14.3.3epsilon, and Pl-jun genes 24 h after UVB exposure. Pl-MT and Pl-14.3.3epsilon mRNAs were misexpressed as they were localized in a position different from that observed in wild-type embryos, i.e., the intestine. On the contrary, Pl-jun mRNA has remained localized in the skeletogenic cells despite their displacement in exposed embryos. In conclusion, Cd/UVB exposure affected skeletal patterning producing alternative morphologies in which p38MAPK activation and Pl-MT, Pl-14.3.3epsilon, and Pl-jun gene overexpression seem linked to a protective role against the stress response induced by Cd/UVB.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cadmium / toxicity*
  • Embryo, Nonmammalian / abnormalities*
  • Embryo, Nonmammalian / drug effects
  • Embryo, Nonmammalian / embryology
  • Embryo, Nonmammalian / radiation effects*
  • Enzyme Activation / drug effects
  • Enzyme Activation / radiation effects
  • Paracentrotus / drug effects
  • Paracentrotus / embryology*
  • Paracentrotus / genetics
  • Paracentrotus / radiation effects*
  • RNA, Messenger / genetics
  • Skeleton / abnormalities
  • Skeleton / drug effects
  • Skeleton / embryology
  • Skeleton / radiation effects
  • Up-Regulation / drug effects
  • p38 Mitogen-Activated Protein Kinases / metabolism

Substances

  • RNA, Messenger
  • Cadmium
  • p38 Mitogen-Activated Protein Kinases