title: Rhythmic expression, light entrainment and alpha-MSH modulation of rhodopsin mRNA in a teleost pigment cell line.
abstract: To investigate whether teleost fish GEM-81 erythrophoroma cells were photosensitive, the cells were submitted to constant darkness (DD), 14 h of light and 10 h of darkness (14L:10D), and 10 h of light and 14 h of darkness (10L:14L). The doubling times (hours) were: DD 35.33+/-0.05; 14L:10D 67.85+/-0.04; and 10L:14D 49.60+/-0.08. In order to verify whether proliferation was dependent on light phase length, GEM-81 cells were submitted to 7L: 5D. The proliferation curves and doubling times were similar in 14L:10D and 7L:5D (respectively 69.44+/-0.03 and 67.85+/-0.04), suggesting that the cell cycle was regulated by the length of the light phase within 24 h, or by the light/dark ratio. We have also demonstrated the expression of Carassius retinal rhodopsin mRNA in GEM-81 cells, which cycles in a circadian rhythm, entrained by light. In addition, we showed that alpha-melanocyte stimulating hormone (alpha-MSH, 10(-10) to 10(-8) M), a conspicuous hormone that exerts mitogenic and melanogenic activity in most vertebrates, decreased rhodopsin mRNA in the first 3 days; after 4 days the inhibition was reversed, and after 5 days an increase in rhodopsin mRNA level was elicited. This is the first report of rhythmic expression of extra-ocular rhodopsin and its modulation by light and hormones.
authors.affiliation: Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP, Brazil.
authors.forename: Letícia Hyoo Jung
authors.initials: LHJ
authors.lastname: Im
authors.affiliation: Department of Biology, University of Virginia, Charlotesville, VA, USA.
authors.forename: Mauro Cesar
authors.initials: MC
authors.lastname: Isoldi
authors.affiliation: Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP, Brazil.
authors.forename: Ana Cristina
authors.initials: AC
authors.lastname: Scarparo
authors.affiliation: Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP, Brazil.
authors.forename: Maria Aparecida
authors.initials: MA
authors.lastname: Visconti
authors.affiliation: Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP, Brazil; Department of Biology, University of Virginia, Charlotesville, VA, USA. Electronic address: amdlcast@ib.usp.br.
authors.forename: Ana Maria
authors.initials: AM
authors.lastname: de Lauro Castrucci
mesh_terms: D000818:Animals; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects / Q000528:radiation effects; D002940:Circadian Rhythm / Q000187:drug effects* / Q000528:radiation effects*; D003624:Darkness; D005786:Gene Expression Regulation / Q000187:drug effects / Q000528:radiation effects; D006054:Goldfish / Q000235:genetics*; D008027:Light; D008544:Melanocytes / Q000166:cytology* / Q000187:drug effects / Q000528:radiation effects; D017440:Photoperiod; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012243:Rhodopsin / Q000235:genetics* / Q000378:metabolism; D000521:alpha-MSH / Q000494:pharmacology*
chemical_list: D012333:RNA, Messenger; D000521:alpha-MSH; D012243:Rhodopsin