title: Retinoic acid triggers meiosis initiation via stra8-dependent pathway in Southern catfish, Silurus meridionalis.
abstract: Existing studies demonstrated that retinoic acid (RA) regulates meiotic initiation via stra8-independent pathway in teleosts which lack stra8 in their genomes. However, stra8 was recently identified from several fish species including Southern catfish (Silurus meridionalis). To explore the existence of stra8-dependent pathway in RA mediated meiotic initiation in fishes, in the present study, the genes encoding RA synthase aldh1a2 and catabolic enzyme cyp26a1 and cyp26b1 were cloned from the Southern catfish. By immunohistochemistry, Aldh1a2 signal was observed in gonads of both sexes during the meiotic initiation period. By real-time PCR, differentially expressed gene was observed for cyp26a1, but not for cyp26b1, in gonads during the meiotic initiation. Administration of exogenous RA or inhibition of endogenous RA degradation by either KET (RA catabolic enzyme inhibitor) or cyp26a1 knockdown using CRISPR/Cas9 induced advanced meiotic initiation in the ovaries as demonstrated by increased Stra8/stra8 expression and appearance of oocytes. In contrast, treatment with RA synthase inhibitor DEAB resulted in delayed meiotic initiation and Stra8/stra8 expression in the ovaries, which was rescued by exogenous RA administration. These results indicated that (1) RA triggers the onset of meiosis via stra8-dependent pathway in stra8 existing teleosts, as it does in tetrapods; (2) exogenous RA can rescue the endogenous RA deficiency; (3) Cyp26a1, instead of Cyp26b1, is the key catabolic enzyme involved in meiosis initiation in teleosts. Taken together, RA might trigger meiotic initiation via stra8-dependent and -independent pathway in different teleosts.
authors.affiliation: Key Laboratory of Eco-environments in Three Gorges Reservoir Region (Ministry of Education), School of Life Science, Southwest University, 400715 Chongqing, PR China; Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education), Key Laboratory of Aquatic Science of Chongqing, School of Life Science, Southwest University, 400715 Chongqing, PR China.
authors.forename: Minghui
authors.initials: M
authors.lastname: Li
authors.affiliation: Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education), Key Laboratory of Aquatic Science of Chongqing, School of Life Science, Southwest University, 400715 Chongqing, PR China.
authors.forename: Ruijuan
authors.initials: R
authors.lastname: Feng
authors.affiliation: Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education), Key Laboratory of Aquatic Science of Chongqing, School of Life Science, Southwest University, 400715 Chongqing, PR China.
authors.forename: He
authors.initials: H
authors.lastname: Ma
authors.affiliation: Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education), Key Laboratory of Aquatic Science of Chongqing, School of Life Science, Southwest University, 400715 Chongqing, PR China.
authors.forename: Ranran
authors.initials: R
authors.lastname: Dong
authors.affiliation: Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education), Key Laboratory of Aquatic Science of Chongqing, School of Life Science, Southwest University, 400715 Chongqing, PR China.
authors.forename: Zhilong
authors.initials: Z
authors.lastname: Liu
authors.affiliation: Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education), Key Laboratory of Aquatic Science of Chongqing, School of Life Science, Southwest University, 400715 Chongqing, PR China.
authors.forename: Wentao
authors.initials: W
authors.lastname: Jiang
authors.affiliation: Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education), Key Laboratory of Aquatic Science of Chongqing, School of Life Science, Southwest University, 400715 Chongqing, PR China.
authors.forename: Wenjing
authors.initials: W
authors.lastname: Tao
authors.affiliation: Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education), Key Laboratory of Aquatic Science of Chongqing, School of Life Science, Southwest University, 400715 Chongqing, PR China. Electronic address: wdeshou@swu.edu.cn.
authors.forename: Deshou
authors.initials: D
authors.lastname: Wang
mesh_terms: D000818:Animals; D002397:Catfishes / Q000235:genetics* / Q000378:metabolism*; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics*; D005260:Female; D008297:Male; D008540:Meiosis / Q000235:genetics*; D051379:Mice; D014212:Tretinoin / Q000378:metabolism / Q000627:therapeutic use*
chemical_list: D014212:Tretinoin; D003577:Cytochrome P-450 Enzyme System
keywords: CRISPR/Cas9; Meiotic initiation; RA; Southern catfish; aldh1a2; cyp26a1