Gonad development examination of high-temperature–treated genetically female Nile tilapia

Polymorphism in a sex‐linked DNA marker located on LG23 in Hainan strain of Nile tilapia (Oreochromis niloticus)

“…Another explanation for XX male fish is sex reversal. It is possible that the sex of the XX/XX L fish was reversed by environmental factors, such as temperature (Baroiller, D'Cotta, & Saillant, 2009;Zhao et al, 2020). When the temperature increased from 25 to 35 C, the proportion of male Nile tilapia fry (4 days after hatching) increased from 52.5% to 75.9% after one week of rearing (Khater, Ali, & Mohamed, 2017).…”

“…Because Marker-5 is located on the same Fosmid clone as amhy, separated by a small physical distance, it is considered as a sex-specific marker in Nile tilapia. Marker-5 and derived or similar markers have been used to test the sex genotype of laboratory strains, cultured strains, as well as wild populations (Salirrosas et al, 2017;Sissao et al, 2019;Sultana, Khan, Hossain, & Alam, 2020;Zhao et al, 2020).…”

Molecular and morphological changes in Nile tilapia ( Oreochromis niloticus ) gonads during high‐temperature‐induced masculinization

“…Melo et al (2019) found that differentiated spermatogonia were characterized by a centralized nucleus with one or more nucleoli and little or no nuage in 35 dph tilapia. Additionally, Zhao et al (2020) reported that the period of temperature‐induced gonadal transformation from ovary to testis was 21–39 dpf. In present study, we could see oogonia and an ovarian cavity in the 28XX♀ and 36XX♀ gonads at 35 dpf.…”

“…How temperature influences the process of gonadal development in GSD + TE animals is an important question in biology. A recent study revealed that morphological sexual differentiation in Nile tilapia occurred between 21 and 25 days post hatching (dph) (Melo et al, 2019), and temperature was found to divert genetics‐directed gonadal development at a specific time window of 21–39 days post fertilization (dpf) in tilapia (Zhao et al, 2020). The first morphological signs of gonadal sex differentiation were observed at 7 weeks after hatching (wah) for ovaries at a female‐producing temperature (FPT) of 17°C, and at 6 wah for testis at a male‐producing temperature (MPT) of 29°C in Pejerrey ( Odontesthes bonariensis ) (Fernandino et al, 2008).…”

“…Temperature variation during the thermosensitive period of sex differentiation may affect the expression of many sex differentiation‐related genes, such as transcription factors, steroidogenic enzymes and transforming growth factor‐β (TGFβ) superfamily members, in different species of teleosts, including Nile tilapia (Li et al, 2014; Matsumoto et al, 2013; Parrott et al, 2014; Zhao et al, 2020) and African catfish (Liu et al, 2010). Specifically, the transcription factor double sex and mab ‐ 3 related transcription factor 1 ( dmrt1 ) is widely distributed in invertebrates and vertebrates, and is required for male development (Matson & Zarkower, 2012; Raymond et al, 2000).…”