RESUMO
Parabreviscolexniepini is a recently described caryophyllidean monozoic tapeworm from schizothoracine fish on the Tibetan Plateau. In the present study, the complete mitochondrial genome of P.niepini is determined for the first time. The mitogenome is 15,034 bp in length with an A+T content of 59.6%, and consists of 12 protein-encoding genes, 22 tRNA genes, two rRNA genes, and two non-coding regions. The secondary structure of tRNAs exhibit the conventional cloverleaf structure, except for trnS1 (AGN) and trnR, which lack DHU arms. The anti-codon of trnS1 (AGN) in the mitogenome of P.niepini is TCT. The two major non-coding regions, 567 bp and 1428 bp in size, are located between trnL2 and cox2, trnG and cox3, respectively. The gene order of P.niepini shows a consistent pattern with other caryophyllideans. Phylogenetic analysis based on mitogenomic data indicates that P.niepini has a close evolutionary relationship with tapeworms Breviscolexorientalis and Atractolytocestushuronensis.
RESUMO
The intestinal microbiota has received increasing attention, as it influences growth, feed conversion, epithelial development, immunity as well as the intrusion of pathogenic microorganisms in the intestinal tract. In this study, pyrosequencing was used to explore the bacterial community of the intestine in gibel carp (Carassius auratus gibelio), and the origin of these microorganisms. The results disclosed great bacterial diversities in the carp intestines and cultured environments. The gibel carp harbored characteristic intestinal microbiota, where Proteobacteria were predominant, followed by Firmicutes. The analysis on the 10 most abundant bacterial operational taxonomic units (OTUs) revealed a majority of Firmicutes in the intestinal content (by decreasing order: Veilonella sp., Lachnospiraceae, Lactobacillales, Streptococcus sp., and Lactobacillus sp.). The second most abundant OTU was Rothia sp. (Actinobacteria). The most likely potential probiotics (Lactobacillus sp., and Bacillus sp.) and opportunists (Aeromonas sp., and Acinetobacter sp.) were not much abundant. Bacterial community comparisons showed that the intestinal community was closely related to that of the sediment, indicating the importance of sediment as source of gut bacteria in gibel carp. However, 37.95 % of the OTUs detected in feed were retrieved in the intestine, suggesting that food may influence markedly the microbiota of gibel carp, and therefore may be exploited for oral administration of probiotics.
