No abstract

DNA barcoding based on a fragment of the cytochrome c oxidase subunit I (COI) gene in the mitochondrial genome is widely applied in species identification and biodiversity studies. The aim of this study was to establish a comprehensive barcoding reference database of fishes in the Taiwan Strait and evaluate the applicability of using the COI gene for the identification of fish at the species level. A total of 284 mitochondrial COI barcode sequences were obtained from 85 genera, 38 families and 12 orders of fishes. The mean length of the sequences was 655 base pairs. The average Kimura two parameter (K2P) distances within species, genera, families, orders and classes were 0.21%, 6.50%, 23.70% and 25.60%, respectively. The mean interspecific distance was 31-fold higher than the mean intraspecific distance. The K2P neighbor-joining trees based on the sequence generally clustered species in accordance with their taxonomic classifications. High efficiency of species identification was demonstrated in the present study by DNA barcoding, and we conclude that COI sequencing can be used to identify fish species.

One-dimensional nanosized core/shell PN-junctions are formed from N-type SnO 2 nanorods (synthesized via a hydrothermal method; diameter ∼10 nm, length ∼100 nm) uniformly coated with P-type CuO nanoparticles (diameter ∼4 nm). Gas sensors are realized from these PN-junction nanorods, and their resistances greatly decrease upon exposed to H 2 S at room temperature. The sensitivity against 10 ppm H 2 S at 60 °C is up to 9.4 × 10 6 . At the same time, the sensors have very good selectivity against H 2 S. Such good performances are probably attributed to the destruction of PN-junctions and the small size effect of nanostructures. Our results imply that one-dimensional heterostructured nanomaterials are promising candidates for high-performance gas sensors.