Microbial diversity of intestinal contents and mucus in yellow catfish (Pelteobagrus fulvidraco)

In this study, traditional culture-based techniques and the 16S rDNA sequencing method were used to investigate the microbial community of the intestinal contents and mucosal layer in the intestine of yellow catfish (Pelteobagrus fulvidraco). Eleven phylotypes were detected from culturable microbiota, and their closest relatives were Plesiomonas, Yersinia, Enterobacter, Shewanella, Aeromonas, Vibrio, and Myroides. Forty-four phylotypes were retrieved from 100 positive clones from intestinal contents (library C), and 21 phylotypes were detected in the 57 positive clones from intestinal mucus (library M), most of which were affiliated with Proteobacteria (>50% of the total). However, the bacterial groups OP10 and Actinobacteria detected in library C were not found in library M, suggesting that the abundance and diversity of bacterial populations in mucus might be different from the microbiota in gut contents, and that some microbial species poorly colonized the gut mucosal layer. (C) 2010 Published by Elsevier B.V

Occurrence of Camallanus cotti in greatly diverse fish species from Danjiangkou Reservoir in central China

Two thousand four hundred fifty-eight fish comprised of 53 species were captured in the Danjiangkou Reservoir, in the northwestern part of Hubei Province, central China during 2004, to examine Camallanus cotti infections. We found that 19 cypriniform, 3 siluriforme, and 4 perciforme fishes were infected by the nematode. Our study revealed the species, Hemiculter bleekeri bleekeri, Culter oxycephaloide, Pseudolaubuca sinensis, Acanthobrama simony, Mylopharyngodon piceus, Ctenopharyngodon idella, Gnathopogon imberbis, G. argentatus, Saurogobio dabryi, S. dumerili, Gobiobotia ichangensis, Liobagrus marginatoides, and Ctenogobius shennongensis as new hosts of the worm. The number and range of fish host species found in this survey were much greater than any of the previous investigations. The mean prevalence, prevalence, mean abundance, and intensity of infection varied in different fish species, indicating a possible host preference. Moreover, we suggest that this nematode is a native parasite of cypriniform fishes in China, perhaps initially in the reaches of the Yangtze River.Two thousand four hundred fifty-eight fish comprised of 53 species were captured in the Danjiangkou Reservoir, in the northwestern part of Hubei Province, central China during 2004, to examine Camallanus cotti infections. We found that 19 cypriniform, 3 siluriforme, and 4 perciforme fishes were infected by the nematode. Our study revealed the species, Hemiculter bleekeri bleekeri, Culter oxycephaloide, Pseudolaubuca sinensis, Acanthobrama simony, Mylopharyngodon piceus, Ctenopharyngodon idella, Gnathopogon imberbis, G. argentatus, Saurogobio dabryi, S. dumerili, Gobiobotia ichangensis, Liobagrus marginatoides, and Ctenogobius shennongensis as new hosts of the worm. The number and range of fish host species found in this survey were much greater than any of the previous investigations. The mean prevalence, prevalence, mean abundance, and intensity of infection varied in different fish species, indicating a possible host preference. Moreover, we suggest that this nematode is a native parasite of cypriniform fishes in China, perhaps initially in the reaches of the Yangtze River

Composition, Diversity, and Origin of the Bacterial Community in Grass Carp Intestine

Gut microbiota has become an integral component of the host, and received increasing attention. However, for many domestic animals, information on the microbiota is insufficient and more effort should be exerted to manage the gastrointestinal bacterial community. Understanding the factors that influence the composition of microbial community in the host alimentary canal is essential to manage or improve the microbial community composition. In the present study, 16S rRNA gene sequence-based comparisons of the bacterial communities in the grass carp (Ctenopharyngodon idellus) intestinal contents and fish culture-associated environments are performed. The results show that the fish intestinal microbiota harbors many cellulose-decomposing bacteria, including sequences related to Anoxybacillus, Leuconostoc, Clostridium, Actinomyces, and Citrobacter. The most abundant bacterial operational taxonomic units (OTUs) in the grass carp intestinal content are those related to feed digestion. In addition, the potential pathogens and probiotics are important members of the intestinal microbiota. Further analyses show that grass carp intestine holds a core microbiota composed of Proteobacteria, Firmicutes, and Actinobacteria. The comparison analyses reveal that the bacterial community in the intestinal contents is most similar to those from the culture water and sediment. However, feed also plays significant influence on the composition of gut microbiota

The complete mitochondrial genome of Gyrodactylus gurleyi (Platyhelminthes: Monogenea)

Gyrodactylus gurleyi, was inhabited on the fins and gills of goldfish (Carassius auratus), which belonged to the family Gyrodactylidae. In this study, we sequenced the complete mitochondrial genome of G. gurleyi with the total length of 14 771 bp. The mitogenome contained 12 protein-coding genes (PCGs), 22 tRNA genes, two rRNA genes and two major non-coding regions (NC1 and NC2). The overall AT content was 72.1%. In phylogenetic analysis, G. gurleyi and G. kobayashii clustered together and then united with the clade of other three Gyrodactylus species (G. salaris, G. thymalli and G. derjavinoides) with high nodal support.</p

Adhesion and colonization properties of potentially probiotic Bacillus paralicheniformis strain FA6 isolated from grass carp intestine

As a prerequisite for probiotics to establish and settle in the host intestine, adhesion is an essential criterion for probiotic screening. However, adhesion of probiotics in the intestines of one of the most important cultured fish species globally, the grass carp Ctenopharyngodon idellus, remains understudied. Here, we assessed the adhesion properties of a novel potentially probiotic bacterial strain isolated from the grass carp intestine: Bacillus paralicheniformis FA6 (henceforth FA6). To indirectly determine the adhesion, we compared the hydrophobicity of FA6 with eight other bacterial strains, and found that FA6 had comparatively high hydrophobicity. To assess adhesion directly, we supplemented the feed with FA6 for 2 weeks, and then used immunofluorescence to study the dynamics of FA6 for 220 days after discontinuing the supplementation. The FA6 fluorescence signal plateaued between days 40 and 60, and remained visible in the grass carp guts until day 80. In addition, FA6 was re-isolated on day 220 from intestinal contents. Our results suggest that FA6 has high adhesion ability, and can colonize the grass carp intestine for long periods of time. This research provides a promising foundation for the application of FA6 in aquaculture.</p

Characterization of the bacterial community associated with early-developmental stages of grass carp (Ctenopharyngodon idella)

Bacterial communities in eggs and larvae of grass carp were analysed. During the early-developmental stages, grass carp harboured five bacterial phyla, i.e. Proteobacteria, Bacteroidetes, Verrucomicrobia, Planctomycetes and Firmicutes. However, the composition of bacterial communities varied among the different developmental stages. In eggs, the bacterial communities were dominated by Proteobacteria, while in larvae the dominant bacterial community was Bacterioidetes. With the exception of a large proportion (&gt;50%) of uncultured bacteria, Sphingobacterium (14.75%) and Acinetobacter (13.11%) were the most abundant groups in eggs at the fertilization stage (FS). However, Aermonas was the most abundant group, ranging from 40.54% to 61.76% in eggs at the cleavage (CS), blastula (BS), organ differentiation (ODS) and hatching stages (HS). In larvae after first ingestion (OW), Chitinophagaceae (79.41%) formed the predominant bacterial community. Changes in the bacterial community were further confirmed by statistical analysis, which demonstrated significant differences in the bacterial communities of eggs at FS, eggs from CS to HS and OW. However, no significant difference was found in bacterial communities of eggs from CS to HS. Furthermore, the present study revealed that bacteria related to Chitinophagaceae persisted from CS to OW, suggesting that these bacteria form part of the autochthonous microbiota of the fish.</p

Light and transmission electron microscopy of

Cepedea longa Bezzenberger, 1904, collected from Fejervarya limnocharis (Amphibia, Anura, Ranidae) from Honghu Lake, Hubei Province, China in May–July 2016, is described at both light and transmission electron microscope levels. This is the first electron microscopic study of this species. Cepedea longa possesses a developed fibrillar skeletal system, composed of longitudinal fibrillar bands and transversal fibrils as well as numerous thin microfibrils dispersed in the endoplasm, which may play an important role in morphogenesis and offer some resilience to deformations of the cell. Longitudinal microfibrils are polarizing elements of kineties, bordering the somatic kineties on the left side and possibly responsible for kinetosome alignment. Two types of vesicles exist in the somatic cortex: globular endocytotic vesicles and flattened exocytotic vesicles. As to the nuclei of C. longa, a thick microfibrillar layer was observed to attach to the cytoplasmic face of the nuclear envelope. This fact suggests no necessary connection between the presence of this microfibrillar layer and the number of nuclei. In addition, some unknown tightly-packed microtubular structures in the nucleoplasm were observed for the first time in opalinids; neither their nature nor physiological significance is known. A detailed list of all reported Cepedea species is included

Light and transmission electron microscopy of Cepedea longa (Opalinidae) from Fejervarya limnocharis

Cepedea longa Bezzenberger, 1904, collected from Fejervarya limnocharis (Amphibia, Anura, Ranidae) from Honghu Lake, Hubei Province, China in May–July 2016, is described at both light and transmission electron microscope levels. This is the first electron microscopic study of this species. Cepedea longa possesses a developed fibrillar skeletal system, composed of longitudinal fibrillar bands and transversal fibrils as well as numerous thin microfibrils dispersed in the endoplasm, which may play an important role in morphogenesis and offer some resilience to deformations of the cell. Longitudinal microfibrils are polarizing elements of kineties, bordering the somatic kineties on the left side and possibly responsible for kinetosome alignment. Two types of vesicles exist in the somatic cortex: globular endocytotic vesicles and flattened exocytotic vesicles. As to the nuclei of C. longa, a thick microfibrillar layer was observed to attach to the cytoplasmic face of the nuclear envelope. This fact suggests no necessary connection between the presence of this microfibrillar layer and the number of nuclei. In addition, some unknown tightly-packed microtubular structures in the nucleoplasm were observed for the first time in opalinids; neither their nature nor physiological significance is known. A detailed list of all reported Cepedea species is included

Transcriptomic Differences between Free-Living and Parasitic Chilodonella uncinata (Alveolata, Ciliophora)

Chilodonella uncinata is a facultatively parasitic ciliate, which can opportunistically parasitize on fish gills and fins, and sometimes even cause host mortality. Previous molecular studies of C. uncinata mainly focused on genetic diversity and molecular evolution. There are currently no transcriptome reports studying differences between free-living and parasitic C. uncinata. We addressed this by sequencing transcriptomes of these two C. uncinata lifestyle types using Smart-seq2 and Illumina HiSeq technologies. In total, 1040 differentially expressed genes (DEGs) were identified. Compared with the free-living type, 494 genes of the parasitic type were downregulated and 546 genes were upregulated. These DEGs were identified through BLAST with NCBI-nr, Swiss-Port, and Pfam databases and then annotated by GO enrichment and KEGG pathway analysis. The results showed that parasitism-related genes such as heat shock proteins (HSPs), actin I, and leishmanolysin were significantly upregulated in parasitic C. uncinata. The ciliary-related dynein heavy chain also had a higher expression in parasitic C. uncinata. Furthermore, there were significant differences in the amino acid metabolism, fatty acid metabolism, lipid metabolism, and TCA cycle. This study increases the volume of molecular data available for C. uncinata and contributes to our understanding of the mechanisms underlying the transition from a free-living to a parasitic lifestyle

The Genome of the Mitochondrion-Related Organelle in Cepedea longa, a Large Endosymbiotic Opalinid Inhabiting the Recta of Frogs

Mitochondrion-related organelles (MROs) are loosely defined as degenerated mitochondria in anaerobic and microaerophilic lineages. Opalinids are commonly regarded as commensals in the guts of cold-blooded amphibians. It may represent an intermediate adaptation stage between the conventional aerobic mitochondria and derived anaerobic MROs. In the present study, we sequenced and analyzed the MRO genome of Cepedea longa. It has a linear MRO genome with large inverted repeat gene regions at both ends. Compared to Blastocystis and Proteromonas lacertae, the MRO genome of C. longa has a higher G + C content and repeat sequences near the central region. Although three Opalinata species have different morphological characteristics, phylogenetic analyses based on eight concatenated nad genes indicate that they are close relatives. The phylogenetic analysis showed that C. longa clustered with P. lacertae with strong support. The 18S rRNA gene-based phylogeny resolved the Opalinea clade as a sister clade to Karotomorpha, which then further grouped with Proteromonas. The paraphyly of Proteromonadea needs to be verified due to the lack of MRO genomes for key species, such as Karotomorpha, Opalina and Protoopalina. Besides, our dataset and analyses offered slight support for the paraphyly of Bigyra