In the present study we
In the present study, we found that the up-regulatory effects of androgens on ep1 transcripts might be mediated by Arα in the olfactory rosette of B. sinensis. However, in mammals, there is no evidence of AR expression in either the vomeronasal organ or the sensory epithelium of main olfactory epithelium, suggesting the regulatory effects of androgens on olfactory receptors are not mediated by AR . It is reported that Ar gene duplication which gave rise to the two different teleost Ars probably occurred during teleost-specific genome duplication . The teleost Arβ is more closely related to AR from mammals, 5(S),6(R)-7-trihydroxymethyl Heptanoate and reptiles, while Arα exhibits sequence divergence [, , ]. In the present study, we observed that Arα but not Arβ played a role in androgen-induced up-regulation of ep1. It is likely that the Arα which has been evolved in the teleost lineage might acquire a new function in olfaction, and this new function might not be present in higher vertebrates.
In summary, we report that 11-KT stimulates the expression of ep1 via Arα in the olfactory rosette of B. sinensis. This mechanism might explain the observations that, compared to immature fish, mature male B. sinensis have both greater EOG sensitivity to the sex pheromone PGE2 and higher expression of ep1 in their olfactory rosettes. To our knowledge, this is the first report describing the molecular mechanism by which androgens regulate the olfactory sensitivity to a prostaglandin sex pheromone in a teleost [30,31].
Declaration of interest
Funding This study was supported by National Natural Science Foundation of China (No. 31672628 and 41276129), the fund for Doctor Station of the Ministry of Education, China (No. 20120121110029), and Program for New Century Excellent Talents in Fujian Province University.
Introduction All organisms, including humans, are exposed to environmental stresses, including industrial chemicals. The majority of these chemicals act as xenobiotics and may cause toxicity depending on the dose and physiological conditions of the host. The host may metabolize or detoxify the chemicals to less reactive chemical species that can be more easily eliminated from the body. However, in rare cases, organisms harbor proteins that specifically bind to certain kinds of chemicals for detoxification, for example, metallothionein, a heavy metal–binding protein (Vasak and Meloni, 2011). Another example is aryl hydrocarbon receptor (AhR), which responds to halogenated aromatic compounds, such as dioxins, although the receptor–chemical binding in this case does not reduce but induces toxicity (Mimura and Fujii-Kuriyama, 2003). The toxicity includes carcinogenesis, reproductive toxicity, immunotoxicity, and neurotoxicity (WHO, 2002). Dioxins are reported to be persistent and ubiquitous environmental contaminants. They are found not only in environmental media, such as air, water, soil, and sediment, but also in the body of various animal species, including humans. Dioxins include three groups of chemicals: polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (PCBs). These compounds are unique in that their toxicity manifests in a receptor-dependent manner and that its intensity depends on the association constant of each congener with AhR (Van den Berg et al., 1998, 2006). Among all congeners, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) has been used as a prototype because it most avidly binds to AhR (Poland and Glover, 1980) and is considered to be the most toxic congener (Schecter and Gasiewicz, 2003). Once AhR ligand, such as TCDD, enters the cells and binds to AhR in the cytoplasm, it is activated in the presence of cofactors and transferred to the nucleus, and dimerizes with AhR nuclear translocator (Arnt) and binds to the AhR-responsive element (AhRE), also called dioxin-responsive element or xenobiotic-responsive element, in the promoter region in various genes. Activation of these genes may lead to abnormal responses, manifesting toxicities (Beischlag et al., 2008; Mimura and Fujii-Kuriyama, 2003; Puga et al., 2009). It has been established that AhR is an essential factor for various types of toxicities, including thymic atrophy, immune suppression, wasting syndrome, cleft palate and hydronephrosis, which was evidenced by independently producing AhR null mice in three laboratories (Gonzalez and Fernandez-Salguero, 1998; Mimura et al., 1997; Peters et al., 1999; Schmidt et al., 1996). However, how the putative molecules that are involved in downstream of AhR signaling remained to be unclear.