Differential expression of Gnrh2, Gthβ, and Gthr genes in sterile triploids and fertile tetraploids

Key Laboratory of Protein Chemistry and Developmental Biology of the State Education Ministry of China, College of Life Sciences, Hunan Normal University, Changsha, 410081, China.
Cell and Tissue Research (Impact Factor: 3.57). 09/2009; 338(1):151-9. DOI: 10.1007/s00441-009-0850-6
Source: PubMed


Gonadotropin-releasing hormone (GnRH), gonadotropin hormone (GTH), and gonadotropin hormone receptor (GTHR) are the pivotal signal molecules of the hypothalamic-pituitary-gonad (HPG) axis, which plays a crucial role in regulating gonadal development in vertebrate. In this study, we comparatively analyze the expression characteristics of Gnrh2, Gthbeta, and Gthr in red crucian carp diploids, triploids, and allotetraploids. The expression patterns of these genes are similar in the three fish ploidy types: the Gnrh2 gene is expressed in midbrains, pituitaries, and gonads; the Gthbeta gene is expressed in pituitaries; the Gthr gene is mainly expressed in gonads. These results indicate that the three genes participate in the regulation of gonadal development. By real-time polymerase chain reaction and in situ hybridization, we find that, among these three fish ploidy types, the expression level of Gthr in the gonads of triploids is lower than those of diploids and tetraploids; this weakens the combination of GTHR with GTH released from the pituitary and leads to the sterility of triploids, since the gonad cannot produce enough sex steroids. In addition, the low expression of Gthr in triploids may affect the down-regulation of Gthbeta, which then affects the down-regulation of Gnrh2; hence, the expression levels of Gnrh2 and Gthbeta genes in triploids are the highest after the breeding season. In conclusion, the differential expression of Gnrh2, Gthbeta, and Gthr in triploids and tetraploids is related to their sterility and bisexual fertility, respectively.

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Available from: Shaojun Liu, Feb 04, 2015
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    • "GnRH2 is involved in sexual behavior and food intake in goldfish (Canosa et al. 2008; Matsuda et al. 2008; Volkoff and Peter 1999), auditory processing as part of the perception of courtship and aggressive social signals in sergeant fish (Maruska and Tricas 2011), and sex change in the black porgy (An et al. 2008). Additionally, the presence of GnRH2 binding sites in the pituitary and hypothalamic area of non-mammalian vertebrates has led to the speculation that GnRH2 plays a hypophysiotropic role (Guzman et al. 2009; Long et al. 2009). In several teleosts including anabantids, GnRH3 might be involved in nest-building behavior and the regulation of pituitary gene expression (Levy et al. 2009; Ogawa et al. 2006; Xu et al. 2011; Yamamoto et al. 1997). "
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