Inducible male infertility by targeted cell ablation in zebrafish testis.
To generate a zebrafish model of inducible male sterility, we expressed an Escherichia coli nitroreductase (Ntr) gene in the male germ line of zebrafish. The Ntr gene encodes an enzyme that can convert prodrugs such as metronidazole (Met) to cytotoxins. A fusion protein eGFP:Ntr (fusing Ntr to eGFP) under control of approximately 2 kb putative promoters of the zebrafish testis-specific genes, A-kinase anchoring protein-associated protein (Asp), outer dense fibers (Odf), and sperm acrosomal membrane-associated protein (Sam) was expressed in the male germ line. Three independent and four compound transgenic zebrafish lines expressing eGFP:Ntr were established. Female carriers were fertile, while males exhibited different levels of sterility and appeared normal, otherwise. Developmental analysis shows that germ cells survived and testes were normal before Met treatment, but that the testes of all male transgenic zebrafish exhibited variously depleted prospermatogonia after Met treatment. Particularly in a triple-transgenic line, Tg(AOS-eGFP:Ntr)[Tg(Asp-eGFP:Ntr; Odf-eGFP:Ntr; Sam-eGFP:Ntr)], the transgenic males had very small testes that were virtually devoid of germ cells, and the residual germ cells had almost completely disappeared after 2 weeks of Met treatment. These zebrafish transgenic lines show the complete testis specificity of inducible male sterility after Met treatment and reveal a period of the Ntr/Met ablation activity just prior to formation of the definitive adult spermatogonial cell population. This study demonstrates that combined genetic and pharmacological methods for developing an "infertile breeding technology" have practical application in controlling genetically modified (GM) fish breeding and meet the standards of biological and environment safety for other GM species.
Hsu
Chia-Chun
CC
Department of Radiology, Tri-Service General Hospital, 325, Cheng-Kung Road Sec. 2, Taipei 114, Taiwan, Republic of China.
Hou
Min-Fon
MF
Hong
Jiann-Ruey
JR
Wu
Jen-Leih
JL
Her
Guor Mour
GM
D055011:Ablation Techniques / Q000379:methods / Q000662:veterinary*; D000595:Amino Acid Sequence; D000818:Animals; D030801:Animals, Genetically Modified; D000890:Anti-Infective Agents / Q000494:pharmacology; D001483:Base Sequence; D004926:Escherichia coli / Q000235:genetics; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D005260:Female; D005298:Fertility / Q000235:genetics; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D007248:Infertility, Male / Q000139:chemically induced / Q000235:genetics; D008297:Male; D008795:Metronidazole / Q000494:pharmacology; D008969:Molecular Sequence Data; D009601:Nitroreductases / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D016415:Sequence Alignment; D013091:Spermatogenesis / Q000187:drug effects / Q000235:genetics; D013737:Testis / Q000187:drug effects / Q000502:physiology*; D015027:Zebrafish / Q000235:genetics* / Q000378:metabolism; D029961:Zebrafish Proteins / Q000235:genetics
D000890:Anti-Infective Agents; D029968:Escherichia coli Proteins; D029961:Zebrafish Proteins; D008795:Metronidazole; C116053:NfsA protein, E coli; D009601:Nitroreductases