Multiple spinal gas in an 86-year-old diabetic man.

Although spinal gas is common and can be found in various sites and lesions, it should prompt a search for the underlying cause, given that the clinical significance of ectopic gas varies from benign to scary. Spinal gas can occur in the traumatic, iatrogenic, degenerative, osteoporotic, infectious, or neoplastic lesions. The imaging similarity may cause the misdiagnosis or delayed diagnosis which sometimes requires immediate attention. The pattern of gas distribution, detailed appearance, clinical history, and findings on examination can provide clues to diagnosis. Computed tomography is the best method for sensitive detection of gas.

Homozygous Mutation of gsdf Causes Infertility in Female Nile Tilapia (Oreochromis niloticus).

Gonadal somatic cell-derived factor (Gsdf) is a member of the TGF-ß superfamily, which exists mainly in fishes. Homozygous gsdf mutations in Japanese medaka and zebrafish resulted in infertile females, and the reasons for their infertility remain unknown. This study presents functional studies of Gsdf in ovary development using CRISPR/Cas9 in Nile tilapia (Oreochromis niloticus). The XX wild type (WT) female fish regularly reproduced from 12 months after hatching (mah), while the XX gsdf-/- female fish never reproduced and were infertile. Histological observation showed that at 24 mah, number of phase IV oocyte in the XX gsdf-/- female fish was significantly lower than that of the WT fish, although their gonadosomatic index (GSI) was similar. However, the GSI of the XX gsdf-/- female at 6 mah was higher than that of the WT. The mutated ovaries were hyperplastic with more phase I oocytes. Transcriptome analysis identified 344 and 51 up- and down-regulated genes in mutants compared with the WT ovaries at 6 mah. Some TGF-ß signaling genes that are critical for ovary development in fish were differentially expressed. Genes such as amh and amhr2 were up-regulated, while inhbb and acvr2a were down-regulated in mutant ovaries. The cyp19a1a, the key gene for estrogen synthesis, was not differentially expressed. Moreover, the serum 17ß-estradiol (E2) concentrations between XX gsdf-/- and WT were similar at 6 and 24 mah. Results from real-time PCR and immunofluorescence experiments were similar and validated the transcriptome data. Furthermore, Yeast-two-hybrid assays showed that Gsdf interacts with TGF-ß type II receptors (Amhr2 and Bmpr2a). Altogether, these results suggest that Gsdf functions together with TGF-ß signaling pathway to control ovary development and fertility. This study contributes to knowledge on the function of Gsdf in fish oogenesis.

Genome-wide identification, evolution of DNA methyltransferases and their expression during gonadal development in Nile tilapia.

DNA methyltransferases (dnmts) are responsible for DNA methylation and play important roles in organism development. In this study, seven dnmts genes (dnmt1, dnmt2, dnmt3aa, dnmt3ab, dnmt3ba, dnmt3bb.1, dnmt3bb.2) were identified in Nile tilapia. Comprehensive analyses of dnmts were performed using available genome databases from representative animal species. Phylogenetic analysis revealed that the dnmts family were highly conserved in teleosts. Based on transcriptome data from eight adult tilapia tissues, the dnmts were found to be dominantly expressed in the head kidney, testis and ovary. Analyses of the gonadal transcriptome data in different developmental stages revealed that all dnmts were expressed in both ovary and testis, and four de novo dnmts (dnmt3aa, dnmt3ab, dnmt3bb.1, dnmt3bb.2) showed higher expression in the testis than in the ovary. Furthermore, during sex reversal induced by Fadrozole, the expression of these four de novo dnmts increased significantly in treated group compared to female control group. By in situ hybridization, the seven dnmts were found to be expressed mainly in phase I and II oocytes of the ovary and spermatocytes of the testis. When gonads were incubated with a methyltransferase inhibitor (5-AzaCdR) in vitro, the expression of dnmts genes were down-regulated significantly, while the expression of cyp19a1a (a key gene in female pathway) and dmrt1 (a key gene in male pathway) increased significantly. Our results revealed the conservation of dnmts during evolution and indicated a potential role of dnmts in epigenetic regulation of gonadal development.

Genome-wide identification, evolution of chromobox family genes and their expression in Nile tilapia.

Chromobox (Cbx) family proteins are transcriptional repressors that involved in epigenetic and developmental processes. In this study, comprehensive analyses of Cbxs were performed using available genome databases from representative animal species. The Cbx family were originated from one Polycomb (Pc) gene like the yeast Pc, which duplicated into two and gave rise to the Pc and the Heterochromatin protein 1 (Hp1) identified in invertebrates from protozoon to lancelet. Rapid expansion of Cbx family members was observed in vertebrates as ~8 (5 Pc and 3 Hp1) were identified in spotted gar, coelacanth and tetrapods. Further expansion of the members to ~14 (9 Pc and 5 Hp1) was observed in teleosts due to the third round genome duplication (3R). Based on transcriptome data from eight adult tilapia tissues, most of the Cbxs were found to be dominantly expressed in the brain, testis, ovary and heart. Analyses of the gonadal transcriptome data from four developmental stages revealed that all Cbxs were expressed in both ovary and testis except Cbx7b, with significant increase of the total and average RPKM from 5 to 90dah (days after hatching). By in situ hybridization, the three most highly and sexual dimorphically expressed Cbx genes in gonads, Cbx1b, Cbx3a and Cbx5, were found to be expressed in phase I and II oocytes of the ovary, and in secondary spermatocytes (Cbx1b and Cbx3a) and spermatids (Cbx5) of the testis. Our results revealed the evolution of Cbx genes and indicated a potential role of Cbxs in epigenetic regulation of gametogenesis.