Androgen receptors in a cichlid fish, <i>Astatotilapia burtoni</i>: Structure, localization, and expression levels

Harbott, Lene K.; Burmeister, Sabrina S.; White, Richard; Vagell, Mike; Fernald, Russell D.

doi:10.1002/cne.21435

Cited by 84 publications

(95 citation statements)

References 88 publications

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“…In the same time frame, steroid hormone (e.g. androgen and estrogen) mRNA levels drop, as do GnRH receptor mRNA levels (Au et al, 2006;Burmeister et al, 2007;Harbott et al, 2007). In addition, certain key electrical properties of GnRH1 neurons change (Greenwood and Fernald, 2004).…”

Section: Dominant Malementioning

confidence: 99%

Cognitive skills and the evolution of social systems

Fernald

2017

Journal of Experimental Biology

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How do animal social skills influence evolution? Complex animal social behaviors require many cognitive skills including individual recognition and observational learning. For social systems to evolve, these abilities need to be transmitted genetically or culturally and supported by the evolution of underlying neural systems. Because animal skill sets are so varied, it seems best to describe animal cognitive behaviors as being a social calculus that can change with experience, which has evolved to match and facilitate the complexity of the social system where it arose. That is, acquiring and using social information in response to a rapidly changing complex world leads to social competence enabling success in essential behavioral interactions. Here, we describe the remarkable suite of social skills discovered in the African cichlid fish Astatotilapia burtoni, including an attention hierarchy, male deception, transitive inference, the mechanistic bases of social dominance, female mate choice and the neural control of female reproductive behavior. The social calculus of this species is presented as an example of a potential causal factor in the evolution of sophisticated social behavior necessary for the evolutionary success of their social system.

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Section: Dominant Malementioning

confidence: 99%

Cognitive skills and the evolution of social systems

Fernald

2017

Journal of Experimental Biology

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“…In teleosts, androgens play crucial roles in the physiological processes regulating sexual differentiation and reproductive development and the spermatogenesis of males by mediating androgen receptors (ARs) (Harbott et al 2007). ARs belong to a large family of nuclear hormone receptors that are ligand-dependent transcription factors with highly conserved DNA-binding domains and moderately conserved ligand-binding domains (Borg 1994.…”

Section: Introductionmentioning

confidence: 99%

Effects of the Herbicide Pendimethalin on Hormone Receptor Expressions and Dorsal Fin Biometrics in Thai Medaka, <I>Oryzias Minutillus</I> (Actinopterygii: Beloniformes: Adrianichthyidae)

Ngamniyom

Panyarachun

2012

Acta Icth et Piscat

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Ngamniyom A., Panyarachun B. 2012. Effects of the herbicide pendimethalin on hormone receptor expressions and dorsal fin biometrics in Thai medaka, Oryzias minutillus (Actinopterygii: Beloniformes: Adrianichthyidae). Acta Ichthyol. Piscat. 42 (3) 239-246.Background. Xeno-oestrogens have negative effects on the endocrine systems of wildlife including freshwater fish. Pendimethalin is a herbicide found in the environment which exerts some oestrogenic action in vivo. Dwarf medaka (known also as Thai medaka), Oryzias minutillus Smith, 1945, inhabit the natural aquatic environments. Dorsal fin of this species is a secondary sex character controlled by sex hormones and assumes as a sensitive bioindicator for testing of oestrogenic chemicals. In this study, we aimed to examine the pendimethalin effects on hormone receptor expressions and dorsal fin biometrics in adult Thai medaka. Materials and methods. Pendimethalin effects on the androgen receptor (AR) and estrogen receptor (ER) β expressions in dorsal fins were determined by semi-quantitative RT-PCR. The fin biometry was presented as the values (%) of the dorsal fin length (DFL) divided by the standard length (SL).Results. In males, AR levels decreased when the fish were exposed to 0.1 µg · mL -1 pendimethalin for 60 days and were exposed to 1 µg · mL -1 for 30 and 60 days. In females, a 60-day treatment with 1 µg · mL -1 caused AR levels to decrease. Conversely, in males, ERβ levels increased after 30 and 60 days of treatment with 1 µg · mL -1 . In females, ERβ levels increased after 30 days of treatment with 1 µg · mL -1 and 60 days of treatment with 0.1 µg · mL -1 . In males, values of DFL/SL% decreased after exposure to 1 µg · mL -1 for 60 days. Additionally, we observed 4 testis-ova among 30 gonads from males treated with 1 µg · mL -1 for 60 days. Conclusion.Our results suggest that pendimethalin may interfere with endocrine processes via hormone receptors, leading to the feminisation of dorsal fins and gonads in Thai medaka.

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“…As these neurons are the critical control point through which the brain signals the gonads, we wanted to understand what hormonal signals might influence their activity. We previously used in situ hybridization to show that androgen receptors are expressed in GnRH1 neurons (Harbott et al, 2007), and here, we used this technique to localize GR and MR. To quantify effects, we used quantitative PCR (qPCR) on microdissected regions of the POA containing GnRH1 neurons to determine whether expression levels of the steroid receptor genes were changed in ND males. …”

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confidence: 99%

Social regulation of cortisol receptor gene expression

Korzan

Grone

Fernald

2014

Journal of Experimental Biology

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In many social species, individuals influence the reproductive capacity of conspecifics. In a well-studied African cichlid fish species, Astatotilapia burtoni, males are either dominant (D) and reproductively competent or non-dominant (ND) and reproductively suppressed as evidenced by reduced gonadotropin releasing hormone (GnRH1) release, regressed gonads, lower levels of androgens and elevated levels of cortisol. Here, we asked whether androgen and cortisol levels might regulate this reproductive suppression. Astatotilapia burtoni has four glucocorticoid receptors (GR1a, GR1b, GR2 and MR), encoded by three genes, and two androgen receptors (ARα and ARβ), encoded by two genes. We previously showed that ARα and ARβ are expressed in GnRH1 neurons in the preoptic area (POA), which regulates reproduction, and that the mRNA levels of these receptors are regulated by social status. Here, we show that GR1, GR2 and MR mRNAs are also expressed in GnRH1 neurons in the POA, revealing potential mechanisms for both androgens and cortisol to influence reproductive capacity. We measured AR, MR and GR mRNA expression levels in a microdissected region of the POA containing GnRH1 neurons, comparing D and ND males. Using quantitative PCR (qPCR), we found D males had higher mRNA levels of ARα, MR, total GR1a and GR2 in the POA compared with ND males. In contrast, ND males had significantly higher levels of GR1b mRNA, a receptor subtype with a reduced transcriptional response to cortisol. Through this novel regulation of receptor type, neurons in the POA of an ND male will be less affected by the higher levels of cortisol typical of low status, suggesting GR receptor type change as a potential adaptive mechanism to mediate high cortisol levels during social suppression. KEY WORDS: Cichlid, Glucocorticoid receptors, Social stress, Androgen receptors INTRODUCTIONSocial status hierarchies are a ubiquitous organizing principle of social systems in many animal species from ants (Wilson, 2000) to primates (Cheney and Seyfarth, 1990), including humans (Chiao et al., 2009). Such hierarchies typically regulate access to resources including territories, food and/or mates, granting individuals of high status access to these resources and requiring those of low status to find alternative solutions to survive. In many species, the reproductive capacity of low status individuals is reduced and mating is not possible because of behavioral and physiological changes (e.g. Willisch et al., 2012). Typically, aggressive encounters establish and maintain social rank, which, in turn, produces significant differences in reproductive capacity. In such social systems, levels of stress and reproductive hormones directly reflect the social rank of individuals and may play a causal role in behavioral and physiological changes. RESEARCH ARTICLEThe relationship between social dominance and reproductive physiology has been well studied in an African cichlid fish, Astatotilapia burtoni (Günther 1894), in which status regulates both reproductive access and...

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Androgen receptors in a cichlid fish, Astatotilapia burtoni: Structure, localization, and expression levels

Cited by 84 publications

References 88 publications

Cognitive skills and the evolution of social systems

Cognitive skills and the evolution of social systems

Effects of the Herbicide Pendimethalin on Hormone Receptor Expressions and Dorsal Fin Biometrics in Thai Medaka, <I>Oryzias Minutillus</I> (Actinopterygii: Beloniformes: Adrianichthyidae)

Social regulation of cortisol receptor gene expression

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