Search

Darwin's finches are the most classic case of evolution. Early studies on the evolution of this species were mainly based on morphology. Until now, the mitochondrial genome of Geospiza magnirostris has been sequenced and the study explored the characteristics of the complete genome of G. magnirostris and verified the evolutionary position of it. The 13 PCGs initiated by ATN codons. The stop codons of three PCGs (ND2, COX3 and ND4) were incomplete, with only T- or TA- replacing complete form TAA or TAG. All the tRNA genes expressed a typical cloverleaf secondary structure, except for tRNASer1(AGY), whose dihydrouridine (DHU) arm was lack and instead with a simple loop. In the sequence of the control region of G. magnirostris, we found six simple repeat tandem sequences with a total length of 42 bp. Two characteristic conserved overlapping junction (ATGCTAA) and (CAAGAAAG) were observed as reported for eight selected Passeriformes birds. A special conserved overlapping junction (ATCTTACC) involved in mitochondrial transcription termination was found between tRNATyr and COX1 in G. magnirostris's control region. Four most frequently used amino acids in G. magnirostris's PCGs were Leu1 (CUN), Ile, Thr, Ala. The codon usage of G. magnirostris was relatively average, and there was no particular bias. The ratio Ka/Ks results showed that G. magnirostris receives less natural selection pressure. The phylogenetic relationships and cluster analysis of relative codon usage showed that G. magnirostris and Thraupis episcopus clustered in one branch. The phylogenetic position of G. magnirostris was consistent with the traditional taxonomic of Thraupis. The results supported the conclusion that G. magnirostris belongs to the morphological classification of the family Thraupidae. [ABSTRACT FROM AUTHOR]

Background: Although transfer RNA (tRNA) has been found to be the main source of a rich class of noncoding RNA, the tRNA‐derived small RNA (tsRNA) has been proved to play an irreplaceable role in the human body, and its dynamic imbalance could affect the progress of the disease. However, the research on tsRNA in oral submucous fibrosis (OSF) is still scarce. Methods: We sequenced the OSF and validated it by PCR. We found that there were significant differences in their expression levels in OSF. Furthermore, bioinformatic analysis was performed to explore the roles of these fragments in oral submucous fibrosis. Results: Of 126 tsRNAs in OSF were dysregulated, including 73 upregulated tsRNAs and 53 downregulated tsRNAs. The downregulated tiRNA‐Val‐CAC‐002, tRF‐Asn‐GTT‐005, tRF‐Trp‐CCA‐007 and upregulated tRF‐Gly‐TCC‐016, tRF‐Pro‐TGG‐009 showed significant differences by qRT‐PCR validation, which were consistent with the results of RNA sequencing. Gene ontology and pathway analysis revealed that tRF‐Gly‐TCC‐016 would possibly promote the formation and progress of OSF through cytokine‐cytokine receptor interaction and cAMP signal pathway, while tiRNA‐Val‐CAC‐002 could be primarily concerned with the transition from OSF to oral squamous cell carcinoma (OSCC). Conclusion: tRNA‐derived fragments are dysregulated and could be involved in the pathogenesis of oral submucous fibrosis. tRF‐Gly‐TCC‐016 and tiRNA‐Val‐CAC‐002 may be new regulatory molecules that could affect the process of OSF by regulating signal pathways through interacting with multiple genes. [ABSTRACT FROM AUTHOR]