title: Identification of the retinoblastoma (Rb) gene and expression in response to environmental stressors in the intertidal copepod Tigriopus japonicus.
abstract: There have been no reports thus far on the structure or molecular characterization of the retinoblastoma (Rb) gene of aquatic animals. Herein we describe the identification of the Rb gene of the intertidal copepod Tigriopus japonicus. In silico analyses revealed the conserved Rb domains of T. japonicus with those of protostomes. Phylogenetic analysis revealed that orthologs of Rb gene were evolved by an ancient split event in deuterostomes, while only a single Rb gene was conserved in protostomes except for Drosophila. The transcription of the T. japonicus Rb gene continuously increased across the molting transition from nauplius to the copepodid and adult stages, suggesting that it may play a developmental role in the molting process of T. japonicus. Information on Rb's response to environmental stressors, including toxin exposure, is lacking in copepods. To examine the transcriptional response to stressful conditions in laboratory culture conditions, copepods were exposed to UV-B radiation and different concentrations of metals, environmental toxins, and biocides. Transcription of the T. japonicus Rb gene was upregulated in response to about half of the 96 h-LD50 of UV-B radiation (12 kJ/m(2)) for 48 h, while the approximate 96 h-LD50 value (24 kJ/m(2)) of UV-B and relatively high concentrations of several toxins and biocides induced the downregulation of T. japonicus Rb mRNA expression. Taken together, our findings suggest that the T. japonicus Rb gene is sensitive to environmentally unfavorable conditions that can induce cell cycle alteration.
authors.affiliation: Department of Biological Science, College of Science, Sungkyunkwan University, Suwon 16419, South Korea.
authors.forename: Bo-Mi
authors.initials: BM
authors.lastname: Kim
authors.affiliation: Department of Biological Science, College of Science, Sungkyunkwan University, Suwon 16419, South Korea; Department of Chemistry, College of Natural Sciences, Hanyang University, Seoul 04763, South Korea.
authors.forename: Chang-Bum
authors.initials: CB
authors.lastname: Jeong
authors.affiliation: Department of Biological Science, College of Science, Sungkyunkwan University, Suwon 16419, South Korea.
authors.forename: Min Chul
authors.initials: MC
authors.lastname: Lee
authors.affiliation: Department of Marine Science, College of Natural Sciences, Incheon National University, Incheon 22012, South Korea. Electronic address: jsrhee@inu.ac.kr.
authors.forename: Jae-Sung
authors.initials: JS
authors.lastname: Rhee
authors.affiliation: Department of Biological Science, College of Science, Sungkyunkwan University, Suwon 16419, South Korea. Electronic address: jslee2@skku.edu.
authors.forename: Jae-Seong
authors.initials: JS
authors.lastname: Lee
mesh_terms: D000818:Animals; D003001:Cloning, Molecular; D033342:Copepoda / Q000235:genetics*; D018076:DNA, Complementary / Q000235:genetics; D017753:Ecosystem; D004785:Environmental Pollutants; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D016161:Genes, Retinoblastoma / Q000235:genetics*; D013312:Stress, Physiological; D014466:Ultraviolet Rays
chemical_list: D018076:DNA, Complementary; D004785:Environmental Pollutants
keywords: Copepod; Environmental pollutant; Rb; Retinoblastoma; Tigriopus japonicus; UV-B