ABSTRACT
Mosquitoes such as Aedes aegypti must consume a blood meal for the nutrients necessary for egg production. Several transcriptome and proteome changes occur post-blood meal that likely corresponds with codon usage alterations. Transfer RNA (tRNA) is the adapter molecule that reads messenger RNA codons to add the appropriate amino acid during protein synthesis. Chemical modifications to tRNA enhance codon decoding, improving the accuracy and efficiency of protein synthesis. Here, we examined tRNA modifications and transcripts associated with the blood meal and subsequent periods of vitellogenesis in A. aegypti. More specifically, we assessed tRNA transcript abundance and modification levels in the fat body at critical times post blood-feeding. Based on a combination of alternative codon usage and identification of particular modifications, we discovered that increased transcription of tyrosine tRNAs is likely critical during the synthesis of egg yolk proteins in the fat body following a blood meal. Altogether, changes in both the abundance and modification of tRNA are essential factors in the process of vitellogenin production after blood-feeding in mosquitoes.
ABSTRACT
BACKGROUND: Testicular germ cell tumor (TGCT) is the most common type of tumor in young men. Type II germ cell tumors including postpubertal-type teratomas are derived from the germ cell neoplasia in situ (GCNIS), whereas prepubertal-type teratomas arise independently of the GCNIS. The consomic mouse strain 129.MOLF-Chr19 (M19) is a suitable murine model of such tumors, but its characterization remains incomplete. OBJECTIVE: Here, we interrogated the suitability of testicular tumors in M19 mice as a model of human TGCT by analyzing their histological features and gene expression signature. MATERIAL AND METHODS: Testes collected from M19 mice of different ages were categorized by macroscopic appearance based on size and the degree of suspected tumorigenesis. Histological sections from selected tumors were stained with Hematoxylin and Eosin, and expression of genes associated with tumorigenesis was determined in frozen tissue samples from a large range of tumors of different subclasses using RT-qPCR and Fluidigm Dynamic Arrays. RESULTS: Macroscopically, testicular specimens appeared very heterogeneous concerning size and signs indicating the presence of a tumor. Histological analysis confirmed the development of teratomas with areas of cells corresponding to all three germ cell layers. Gene expression analyses indicated upregulation of markers related to proliferation, vascular invasive potential and pluripotency, and revealed a strong correlation of gene expression with tumor size and a significant intercorrelation of individual genes. DISCUSSION AND CONCLUSION: TGCT in M19 mice is reminiscent of human testicular teratomas presenting with areas of cells derived from all germ layers and showing a typical gene signature. We thus confirm that these mice can serve as a suitable murine model of pure teratomas for preclinical research.