RÉSUMÉ
The number of dental schools increased from 55 in 2000 to 66 in 2019 in the United States. The number of public, private, and private-state-related dental schools were 40, 22 and 4, respectively. A majority of them were located in most developed areas, such as western, eastern, and southern regions of the country. In the same period, the number of freshman enrollees rose from 4 234 to 6 231 while the average of enrollees kept under 100. On the basis of learning relevant experiences of the United States, it might be necessary for China to expand the overall scale of stomatology education in order to address the shortage of dentists, take measures to increase the number of stomatology schools and improve their distribution, and control the number of enrollees per school to enhance the quality of education.
RÉSUMÉ
OBJECTIVE@#In order to distinguish the traditional Chinese medicine Bupleurum falcatum and its adulterants effectively and develop a better understanding of the factors affecting synonymous codon usage, codon usage patterns of chloroplast genome, we determine the complete chloroplast (cp) genome of B. falcatum and clarify the main factors that influence codon usage patterns of 78 genes in B. falcatum chloroplast genome.@*METHODS@#The total genomic DNA of fresh leaves from a single individual of B. falcatum was extracted with EASYspin plus Total DNA Isolation Kit and 2 μg genome DNA was sequenced using Illumina Hiseq 2500 Sequencing Platform. The cp genome of B. falcatum was reconstructed with MITObim v1.8 and annotated in the program CPGAVAS2 with default parameters. Python script and Codon W were used to calculate the codon usage bias parameters.@*RESULTS@#The full length of B. falcatum cp genome was 155 851 bp, 132 different genes were annotated in this cp genome containing 80 protein-coding genes, 30 tRNA genes, and four rRNA genes. The codon usage models tended to use A/T-ending codons. The neutrality plot, ENC plot, PR2-Bias plot and correspondence analysis showed that both compositional constraint under selection and mutation could affect the codon usage models in B. falcatum cp genome. Furthermore, three optimal codons were identified and most of these three optimal codons ended with G/U.@*CONCLUSION@#The cp genome of B. falcatum has been characterized and the codon usage bias in B. falcatum cp genome is influenced by natural selection, mutation pressure and nucleotide composition. The results will provide much more barcode information for species discrimination and lay a foundation for future research on codon optimization of exogenous genes, genetic engineering and molecular evolution in B. falcatum.