Targeted mutation of secretogranin-2 disrupts sexual behavior and reproduction in zebrafish

Abstract

The luteinizing hormone surge is essential for fertility as it triggers ovulation in females and sperm release in males. We previously reported that secretoneurin-a, a neuropeptide derived from the processing of secretogranin-2a (Scg2a), stimulates luteinizing hormone release, suggesting a role in reproduction. Here we provide evidence that mutation of thescg2aandscg2bgenes using TALENs in zebrafish reduces sexual behavior, ovulation, oviposition, and fertility. Large-scale spawning within-line crossings (n= 82 to 101) were conducted. Wild-type (WT) males paired with WT females successfully spawned in 62% of the breeding trials. Spawning success was reduced to 37% (P= 0.006), 44% (P= 0.0169), and 6% (P< 0.0001) forscg2a−/−,scg2b−/−, andscg2a−/−;scg2b−/−mutants, respectively. Comprehensive video analysis indicates thatscg2a−/−;scg2b−/−mutation reduces all male courtship behaviors. Spawning success was 47% in saline-injected WT controls compared to 11% in saline-injectedscg2a−/−;scg2b−/−double mutants. For these mutants, spawning success increased 3-fold following a single intraperitoneal (i.p.) injection of synthetic secretoneurin-a (P= 0.0403) and increased 3.5-fold with injection of human chorionic gonadotropin (hCG). Embryonic survival at 24 h remained on average lower inscg2a−/−;scg2b−/−fish compared to WT injected with secretoneurin-a (P< 0.001). Significant reductions in the expression of gonadotropin-releasing hormone 3 in the hypothalamus, and luteinizing hormone beta and glycoprotein alpha subunits in the pituitary provide evidence for disrupted hypothalamo-pituitary function inscg2aandscg2bmutant fish. Our results indicate that secretogranin-2 is required for optimal reproductive function and support the hypothesis that secretoneurin is a reproductive hormone.

WITHDRAWN: Exposure to Difenoconazole Induces Reproductive Toxicity of Zebrafish by Interfering Reproductive Behavior

“…Gonadal histological section was examined using an Olympus microscope (Olympus BH-2, Japan). The classi cation of cells at different stages in the gonads was based on previous studies (Hu et al, 2018;Mitchell et al, 2020).…”

“…However, environmental pollutants often induced reproductive toxicity by interfering with gamete formation, such as bisphenol compounds (Ji et (Li et al, 2019b). In vertebrates, sexual behavior coordinates the release of gametes to determine fertility (Mitchell et al, 2020). Nowadays, most studies on the reproductive toxicity of environmental pollutants focus on the formation of gametes, while reproductive behavior is relatively less concerned.…”

Cystic proliferation of germline stem cells is necessary to reproductive success and normal mating behavior in medaka

“…Sexual behavior has been found to be strongly controlled by the brain (Hiraki-Kajiyama et al, 2019;Mitchell et al, 2020;Yang and Shah, 2014), and levels of sex steroid hormones (Hiraki-Kajiyama et al, 2019;Munakata and Kobayashi, 2010). Here, it is important to note that in medaka, the secondary sex characters are induced by sex steroid hormones (Kikuchi et al, 2019;Sato et al, 2008).…”

Cystic proliferation of embryonic germ stem cells is necessary to reproductive success and normal mating behavior in medaka

“…We specifically observed differences in male mating behavior related with stimulation of female spawning and fertilization, such as the duration of quivering and number of convulsions; actions that seems to be conserved in vertebrates, because the ejaculation in male rat is accompanied by severe vibration and significant abdominal contraction (Qin et al, 2017). Sexual behavior has been found to be strongly controlled by the brain (Hiraki-Kajiyama et al, 2019;Mitchell et al, 2020;Yang and Shah, 2014), and levels of sex steroid hormones (Hiraki-Kajiyama et al, 2019;Munakata and Kobayashi, 2010). Here, it is important to note that in medaka, the secondary sex characters are induced by sex steroid hormones (Kikuchi et al, 2019;Sato et al, 2008).…”