It is well accepted that Forkhead box protein L2 (Foxl2) and aromatase (Cyp19a1; the enzyme responsible for estrogen synthesis) are critical for ovarian development in vertebrates. Knockouts of Foxl2 and Cyp19a1 in goat, mouse, and zebrafish have revealed similar but not identical functions across species. Functional analyses of these two genes in other animals are needed to elucidate their conserved roles in vertebrate sexual development. In this study, we established foxl2 and cyp19a1a mutant lines in Nile tilapia. Both foxl2-/- and cyp19a1a-/- XX fish displayed female-to-male sex reversal. Sf1, Dmrt1, and Gsdf were upregulated in the foxl2-/- and the cyp19a1a-/- XX gonads. Downregulation of Cyp19a1a and serum estradiol-17β level, and upregulation of Cyp11b2 and serum 11-ketotestosterone level were observed in foxl2-/- XX fish. The mutant phenotype of foxl2-/- XX individuals could be rescued by 17β-estradiol treatment from 5 to 30 days after hatching (dah). Upregulation of Star1, the enzyme involved in androgen production in tilapia, was also observed in the foxl2-/- XX gonad at 30 and 90 dah. In vitro promoter analyses consistently demonstrated that Foxl2 could suppress the transcription of star1 in a dose-dependent manner. In addition, compared with the control XX gonad, fewer germ cells were detected in the foxl2-/- XX, cyp19a1a-/- XX, and control XY gonads 10 dah. These results demonstrate that Foxl2 promotes ovarian development by upregulating Cyp19a1a expression and repressing male pathway gene expression. These results extend the study of Foxl2 and Cyp19a1a loss of function to a commercially important fish species.

We reported 79 % accuracy of O-arm-based pedicle screw placement in dystrophic NF-1-associated scoliosis. O-arm navigation system does facilitate pedicle screw insertion in dystrophic NF-1-associated scoliosis, demonstrating superiorities in the safety and accuracy of pedicle screw placement in comparison with free-hand technique.

No abstract

No abstract

A new self-assembled nanoparticle platform based on a carboxymethylcellulose (CMC)–ursolic acid (UA) conjugate is presented for the first time.

Germline sexual fate has long been believed to be determined by the somatic environment, but this idea is challenged by recent studies of foxl3 mutants in medaka. Here we demonstrate that the sexual fate of tilapia germline is determined by the antagonistic interaction of dmrt1 and foxl3, which are transcriptionally repressed in male and female germ cells, respectively. Loss of dmrt1 rescued the germ cell sex reversal in foxl3Δ7/Δ7 XX fish, and loss of foxl3 partially rescued germ cell sex reversal but not somatic cell fate in dmrt1Δ5/Δ5 XY fish. Interestingly, germ cells lost sexual plasticity in dmrt1Δ5/Δ5 XY and foxl3Δ7/Δ7 XX single mutants, as aromatase inhibitor and estrogen treatment failed to rescue the respective phenotypes. However, recovery of germ cell sexual plasticity was observed in dmrt1/foxl3 double mutants. Importantly, mutation of somatic cell specific foxl2 resulted in testicular development in foxl3Δ7/Δ7 or dmrt1Δ5/Δ5 mutants. Our findings demonstrate that sexual plasticity of germ cells relies on the presence of both dmrt1 and foxl3. The existence of dmrt1 and foxl3 allows environmental factors to influence the sex fate decision in vertebrates.

Small metal clusters received increasing attention due to their attractive and superior performance in electrocatalytic energy conversion. However, the designable realization of well-dispersed metal clusters is a great challenge owing...

The diverse color patterns of cichlid fishes play an important role in mate choice and speciation. Here we develop the Nile tilapia (Oreochromis niloticus) as a model system for studying the developmental genetics of cichlid color patterns. We identified 4 types of pigment cells: melanophores, xanthophores, iridophores and erythrophores, and characterized their first appearance in wild-type fish. We mutated 25 genes involved in melanogenesis, pteridine metabolism, and the carotenoid absorption and cleavage pathways. Among the 25 mutated genes, 13 genes had a phenotype in both the F0 and F2 generations. None of F1 heterozygotes had phenotype. By comparing the color pattern of our mutants with that of red tilapia (Oreochromis spp), a natural mutant produced during hybridization of tilapia species, we found that the pigmentation of the body and eye is controlled by different genes. Previously studied genes like mitf, kita/kitlga, pmel, tyrb, hps4, gch2, csf1ra, pax7b, and bco2b were proved to be of great significance for color patterning in tilapia. Our results suggested that tilapia, a fish with 4 types of pigment cells and a vertically barred wild-type color pattern, together with various natural and artificially induced color gene mutants, can serve as an excellent model system for study color patterning in vertebrates.