Differential expression of Gnrh2, Gthβ, and Gthr genes in sterile triploids and fertile tetraploids
Differential expression of Gnrh2, Gthβ, and Gthr genes in sterile triploids and fertile tetraploids
复制标题
DOI：
10.1007/s00441-009-0850-6
复制
发表时间：
2009-10-01
影响因子：
3.6
通讯作者：
Liu, Yun
中科院分区：
文献类型：
--
作者：
Long, Yu;Tao, Min;Liu, Yun
促性腺激素释放激素（GnRH）、促性腺激素（GTH）和促性腺激素受体（GTHR）是下丘脑-垂体-性腺（HPG）轴的关键信号分子，在调节脊椎动物性腺发育中起重要作用。本研究比较分析了Gnrh2、Gth β和Gthr在红鲫二倍体、三倍体和异源四倍体中的表达特征。这些基因在三种鱼类倍体类型中的表达模式相似：Gnrh2基因在中脑、垂体和性腺中表达；Gth β基因在垂体中表达；Gthr基因主要在性腺中表达。这些结果表明，这三个基因参与了性腺发育的调控。通过实时聚合酶链反应和原位杂交，我们发现，在这三种鱼倍性类型中，三倍体的性腺中Gthr的表达量低于二倍体和四倍体；这削弱了GTHR与垂体释放的GTH的结合，导致三倍体不育，因为性腺不能产生足够的性类固醇。此外，Gthr在三倍体中的低表达可能会影响Gth β的下调，进而影响Gnrh2的下调；因此，三倍体中Gnrh2和Gth β基因在繁殖季节后表达量最高。综上所述，Gnrh2、Gth β和Gthr在三倍体和四倍体中的差异表达分别与它们的不育性和两性育性有关。
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, Gth beta, 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 Gth beta 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 Gth beta, which then affects the down-regulation of Gnrh2; hence, the expression levels of Gnrh2 and Gth beta genes in triploids are the highest after the breeding season. In conclusion, the differential expression of Gnrh2, Gth beta, and Gthr in triploids and tetraploids is related to their sterility and bisexual fertility, respectively.