Vertebrates originally possess four functional subtypes of G protein-coupled melatonin receptor.

Melatonin receptors (MTNRs) belonging to the G protein-coupled receptor family are considered to consist of three subtypes in vertebrates: MTNR1a, MTNR1b and MTNR1c. Additionally, MTNR1a-like genes have been identified in teleostean species as a fish-specific subtype of MTNR1a. However, similar molecules to this MTNR1a-like gene can be found in some reptiles upon searching the DNA database. We hypothesized that a vertebrate can essentially have four functional subtypes of MTNR as ohnologs. Thus, in the present study we examined the molecular phylogeny, expression patterns and pharmacological profile(s) using the teleost medaka (Oryzias latipes). The four conserved subtypes of MTNR (MTNR1a, MTNR1b, MTNR1c and MTNR1a-like) in vertebrates were classified based on synteny and phylogenetic analysis. The fourth MTNR, termed MTNR1a-like, could be classified as MTNR1d. It was observed by using RT-qPCR that expression patterns differed amongst these subtypes. Moreover, mtnr1a, mtnr1c and mtnr1a-like/mtnr1d expression was elevated during short days compared to long days in diencephalons. All the subtypes were activated by melatonin and transduced signals into the Gi pathway, to perform a cAMP-responsive reporter gene assay. It was shown that MTNR originally consisted of four subtypes: MTNR1a, MTNR1b, MTNR1c and MTNR1d. These subtypes were functional, at least in fish, although some organisms, including mammals, have lost one or two subtypes.

A fourth subtype of retinoic acid receptor-related orphan receptors is activated by oxidized all-trans retinoic acid in medaka (Oryzias latipes).

BACKGROUND: The three known subtypes of the retinoic acid receptor-related orphan receptor (ROR) have been implicated in the control of immunity, brain function, and circadian rhythm in mammals. Here, we demonstrate by phylogenetic analysis that there were originally four subtypes of RORs in vertebrates. One of the novel ror paralogs, rord1 (rorca in the Ensembl database), is conserved among teleosts, but absent in mammals. Using medaka (Oryzias latipes) as a model teleost, we evaluated the expression pattern of this gene, its transactivational properties for endogenic chemicals, and its ability to activate the promoters of putative target genes. RESULTS: In eyes, the transcript of rord1 was expressed at higher levels during the day than at night. Interestingly, cholesterol derivatives, which are well-known ligands for mammalian RORs, did not efficiently promote transcriptional activity via RORd1. Thus we sought to identify the ligands that regulate the transcriptional activity of RORd1 using a luciferase reporter cell-based screening system. Using this system, we identified two metabolites of all-trans retinoic acid (ATRA), 4OH-ATRA and 4-keto ATRA, as potential ligands of RORd1. Moreover, RORd1 activated the promoter of cyp26a1 in a 4OH-ATRA -dependent manner. CONCLUSIONS: A novel ror subtype, rord has two paralogs, rord1 and rord2, in teleost. Rord1 mRNA is highly abundant in the eyes of medaka during light periods, suggesting that rord1 expression is involved in the regulation of circadian rhythm. We identified two ATRA metabolites, 4OH-ATRA and 4 K-ATRA, as endogenous candidate ligands of RORd1. We also show that 4-oxygenated ATRA metabolites have the potential to activate cyp26a1, the metabolic enzyme of ATRA. Our results support the notion that RORd1 is involved in the metabolism of ATRA in medaka.

Chlorophyll-Based Organic-Inorganic Heterojunction Solar Cells.

Solid-state chlorophyll solar cells (CSCs) employing a carboxylated chlorophyll derivative, methyl trans-32 -carboxypyropheophorbide a, as a light-harvesting dye sensitizer chlorophyll (DSC) deposited on mesoporous TiO2 , on which four zinc hydroxylated chlorophyll derivatives were spin-coated for hole transporter chlorophylls (HTCs), are described. Key parameters, including the effective carrier mobility of the HTC films, as determined by the space charge-limited current method, and the frontier molecular orbitals of these DSCs and HTCs, as estimated from cyclic voltammetry and electronic absorption spectra, suggest that both charge separation and carrier transport are favorable. The power conversion efficiencies (PCEs) of the present CSCs with fluorine-doped tin oxide (FTO)/TiO2 /DSC/HTCs/Ag were determined to follow the order of HTC-1>HTC-2>HTC-3>HTC-4, which coincided perfectly with the order of their hole mobilities. The maximum PCE achieved was 0.86 % with HTC-1. The photovoltaic devices studied herein with two types of chlorophyll derivatives as dye sensitizers and hole transporters provide a unique solution for the utilization of solar energy with a view to truly realizing "green energy".