Microbiome dysbiosis inhibits carcinogen-induced murine oral tumorigenesis.

Oral cancer is one of the most common cancers worldwide and ranks fourth for the mortality rate of cancers in males in Taiwan. The oral microbiota is the microbial community in the oral cavity, which is essential for maintaining oral health, but the relationship between oral tumorigenesis and the oral microbiota remains to be clarified. This study evaluated the effect of microbiome dysbiosis on oral carcinogenesis in mice, and the impact of the microbiome and its metabolic pathways on regulating oral carcinogenesis. We found that antibiotics treatment decreases carcinogen-induced oral epithelial malignant transformation. Microbiome analysis based on 16S rRNA gene sequencing revealed that the species richness of fecal specimens was significantly reduced in antibiotic-treated mice, while that in the salivary specimens was not decreased accordingly. Differences in bacterial composition, including Lactobacillus animalis abundance, in the salivary samples of cancer-bearing mice was dramatically decreased. L. animalis was the bacterial species that increased the most in the saliva of antibiotic-treated mice, suggesting that L. animalis may be negatively associated with oral carcinogenesis. In functional analysis, the microbiome in the saliva of the tumor-bearing group showed greater potential for polyamine biosynthesis. Immunochemical staining proved that spermine oxidase, an effective polyamine oxidase, was upregulated in mouse oral cancer lesions. In conclusion, oral microbiome dysbiosis may alter polyamine metabolic pathways and reduce carcinogen-induced malignant transformation of the oral epithelium.

Fish assemblage changes over half a century in the Yellow River, China.

Riverine environments have been threatened by anthropogenic perturbations worldwide, whereby their fish assemblages have been modified by habitat changes and nonendemic species invasions. We assessed changes in fish assemblages by comparing the species presence in historical and contemporary fish data in the Yellow River from 1965 to 2015. The temporal change in species assemblages was found with increased nonendemic species and fewer natives. Fish species richness of the river declined 35.4% over the past fifty years. Moreover, the decreased mean Bray-Curtis dissimilarity among reaches suggested that the fish assemblages of different reaches in the Yellow River were becoming more similar over time. However, temporal patterns of fish assemblages varied among reaches. In the upper Yellow River, higher species richness and more invasive species were found than those in the historical record, while the lower reaches experienced significant species loss. Dam constructions, exotic fish invasions, and flow reductions played the vital role in structuring the temporal fish assemblages in the Yellow River. It is suggested that river basins which experienced different types and levels of stressors by anthropogenic perturbations can produce varied effects on their temporal trends of species assemblages.

The complete mitochondrial genome sequence of Schizopygopsis pylzovi (Cypriniformes: Cyprinidae).

Schizopygopsis pylzovi Kessler (Cypriniformes: Cyprinidae), an endemic species to China, is a major commercial fish in the upper reaches of the Yellow River. The complete mitochondrial DNA genome of S. pylzovi was sequenced. The mitogenome is 16,704 bp in length and includes 13 protein-coding genes, 22 transfer RNA genes, two ribosomal RNA genes and two non-coding regions. The basic composition of S. pylzov is 28.5% for A, 27.0% for T, 26.1% for C, and 18.4% for G, with a slight AT bias of 55.5%. Gene order is similar to that of the typical vertebrate, as is nucleotide composition and codon usage. The complete mitogenome sequence of S. pylzovi would be useful to further phylogenetic analysis and genetic conservation for this endemic species.

[DNA barcoding application of mitochondrial COI gene sequence in medicinal fish of Culter (Pisces: Cyprinidae)].

The sequence variation of medicinal fish of Culter (Pisces: Cyprinidae) was analyzed by using cytochrome c oxidase subunit I (COI) sequencing collected from different regions of the Yangtze River basin, and we examine whether barcoding of COI can be used to discriminate medicinal fish of Culter. The AT content in the COI region of medicinal fish of Culter was higher than that of GC, which was similar with other species of Cypriniformes. Ninty-six percent of nucleotide changes were observed at the 3rd codon position of COI sequence, but the amino acid compositions translated by COI sequences of all Culter fish stayed the same. It is suggested that most synonymous mutations might occur at the 3rd position. The average Kimura-2-parameter (K2P) distance within-species was lower than 1%, and the K2P distance of pairwise-species was 10 times as much as that of within-species. The phylogenetic tree estimated by Neighbour-joining method indicated that species within genera invariably clustered, and generally so did individuals within species. Individuals from operational taxonomic units designated as different Culter species, supporting morphological evidence for each of these being separate species. It is suggested that the COI barcoding can be used to identify medicinal fish species of Culter.