Search

Creative use of 3D printing to create analytical standards greatly increased the sample homogeneity and the accuracy of the desired concentration.

Freshwater salinization is a growing environmental issue caused by various anthropic or natural factors that lead to changes in water chemistry and physical conditions, affecting the survival and diversity of phytoplankton. In this study, we tested the physiological, morphological and interspecific competition of the freshwater cyanobacterium Microcystis aeruginosa and the green algae Scenedesmus obliquus to salinity stress. Results demonstrated that increasing salinity had a significant negative effect on the growth of M. aeruginosa and S. obliquus. M. aeruginosa showed a decline in growth rate with increasing salinity, while S. obliquus showed a lower growth rate under salinity stress but with no significant difference between the two salinity groups. In cocultures, S. obliquus outcompeted M. aeruginosa, and the displacement was accelerated with increasing salinity. The photosynthetic performance of both algae was affected by salinity, the presence of competitors, and the cultivation time. S. obliquus showed morphological variations under salinity stress and the presence of a competitor. The study suggests that salinity stress and competition can have a significant impact on the growth and performance of algae species. The findings of our study suggest that the salinization of freshwater can impact the interspecific interactions among phytoplankton, which play a crucial role in the functioning of freshwater ecosystems.

Nitrite is one of the most common pollutants in high-density aquaculture or in recirculated aquaculture systems. In this study, gene and miRNA expression dynamics were investigated for unveiling the genetic regulation of Eriocheir sinensis in response to acute nitrite stress. Two groups of E. sinensis with different vitality of appendages (i.e., NG and DG) were treated with nitrite-N in 6 and 24 h, respectively. A number of differentially expressed (DE) genes and miRNAs were detected in the pairwise comparisons of the two groups. We found that the DE genes and the target genes of DE miRNAs were significantly enriched into some key pathways, such as metabolic pathways, MAPK signaling pathway, and nitrogen metabolism. Notably, the number of DE genes identified from the pairwise comparison of MNG vs. FNG (NG groups at 6 h and 12 h, respectively) was much larger than that identified from MDG vs. FDG (FG groups at 6 h and 12 h, respectively), indicating that the individuals from strong vitality group had genetic superiority for tolerance of nitrite stress. The similar trend was also observed from the identification of DE miRNAs. Some key genes (e.g., hsp70, mtnd2, act7, hspg2, cam-1) involved in signaling transduction, oxidative phosphorylation, and energy metabolism were detected in this study. Besides, several miRNAs (miR-31, miR-215, miR-142-x) that mediate the calmodulin related genes were also identified, inferring that calcium signaling pathway participates in the responses to nitrite stress in crabs. This study revealed the mRNA and miRNA expression patterns of Chinese mitten crab under sustained nitrite stress and provided the genetic basis for the molecular selective breeding.

The innate immune response of Charybdis japonica treated with Aeromonas hydrophila was explored using bioinformatics. Metabolomics data were integrated with a gut microbial 16S rRNA dataset, together with information on corresponding enzyme activity. The results of the study showed that after being infected with A. hydrophila, some beneficial genera of bacteria in the gut of C. japonica, such as Photobacterium, Rhodobacter, Polaribacter, Psychrilyobacter, Mesoflavibacter, Fusibacter and Phormidium, could directly inhibit Vibrio or produce extracellular polysaccharides with highly effective antibacterial properties. The intestinal probiotics of C. japonica such as Mesoflavibacter have a mutually reinforcing relationship with Phaeobacter, Colwellia, Bacillus, Psychrobacter and Cohaesibacter. Conditional pathogenic bacteria in the gut of healthy crabs may also have such a symbiotic relationship with intestinal probiotics, promoting their growth and reproduction. For example, Phormidium has a mutualistic relationship with Aeromonas and Azopira. Metabolites in the gut of C. japonica infected with A. hydrophila, including beta-alanine metabolism, nitrogen metabolism, inositol phosphate metabolism, galactose metabolism, histidine metabolism, ascorbate and arginine and proline metabolism were increased, with alanine metabolism being the most abundant. The activity of metabolite related enzymes such as lipid peroxidase, phenoloxidase, superoxide dismutase, nitric oxide synthase, glutathione transferase and mid-glutathione decreased and NO levels also decreased. The positive correlation with the probiotic flora suggests that metabolites increase with bacterial abundance and that microbial metabolites or co-metabolites can, in turn, achieve many pleiotropic effects to resist invasion by A. hydrophila. These results may contribute to further research in the resistance of C. japonica to invading pathogens.ImportanceWith the rapid development of the C. japonica farming industry, investors, in pursuit of economic benefits, have encountered problems such as frequent outbreaks of various diseases, resulting in high mortality and huge economic losses. The open water circulation system can give rise to several crab bacterial diseases. Among these, A. hydrophila is a pathogenic bacterium affecting fish and crustaceans, which leads to huge economic losses. Our results suggest that metabolites increased with the abundance of bacteria. It is possible that the autoimmune system and the entry of A. hydrophila into the intestinal tissues of C. japonica react immunologically and that the organism is producing certain metabolites which may be metabolised by various bacteria and absorbed into the circulation. In addition, some of these metabolites are modified or bound in the hepatopancreas to produce microbiota-host co-metabolites. These microbial metabolites or co-metabolites can resist invasion by A. hydrophila.

The objective of this study was to determine the probable pathogen causing the recently discovered hepatopancreas browned disease (HPBD) in Chinese mitten crab (Eriocheir sinensis), an important freshwater aquaculture species. Hepatopancreas material was collected from 30 E. sinensis individuals confirmed as infected using plasma coagulase tests. Genes nuc and femA, both specific for Staphylococcus aureus, were amplified by reverse transcription-PCR from three randomly selected HPBD-infected crabs, specific bands were observed at 191 and 397 bp, and amplified partial sequences aligned perfectly (100%) with published nuc and femA gene sequences using BLAST and GenBank. Four major developmental stages of hepatopancreas histopathological changes were observed in 7-week reverse infection challenge tests in 90 pathogen-induced animals; hepatopancreas material changed colour from orange to yellow, red to brown, and light brown to almost fully necrotised. Optical and transmission electron microscopy revealed similar hepatopancreas pathological characteristics to those of HPBD-infected E. sinensis. The hepatopancreas browning rate of infected crabs (88.89 ± 5.09%) was significantly higher than controls (7.78 ± 1.92%). These results suggest S. aureus is the probable pathogen causing HPBD in E. sinensis, and infection leads to inflammation, atrophy, and complication of hepatopancreatic necrosis.

B52 is a member of the classical serine/arginine (SR)-rich proteins, which are phylogenetically conserved and play significant roles in mRNA maturation, including alternative splicing. In the present study, the docking site, selector sequences and locus control region of the Chinese mitten crab (Eriocheir sinensis) Down syndrome cell adhesion molecule (EsDscam) were identified. Alternative splicing of Dscam is essential to generate different isoforms. We also isolated and characterised the B52 gene from E. sinensis (EsB52). The 876 bp open reading frame of EsB52 encodes a 291 amino acid residue polypeptide, and EsB52 has two RNA recognition motifs (RRMs) at the N-terminus and an arginine/serine-rich domain at the C-terminus. Each RRM contains two degenerate short submotifs, RNP-1 and RNP2. Analysis of tissue distribution revealed that EsB52 mRNA expression was widespread in all tested tissues, and especially high in brain and hemocytes. In hemocytes, EsB52 was upregulated significantly after stimulation with pathogen-associated molecular patterns and bacteria. Furthermore, EsB52 RNAi decreased the number of Ig7 inclusion in mRNA rather than Ig2 or Ig3. Taken together, these findings suggest that EsB52 acts as an alternative splicing activator of EsDscam.

The widespread generation and accumulation of plastic waste has become a globally recognized problem. However, there are limited reports on the adverse effects of nanomaterials on freshwater crustaceans. This study tested the acute effects of different concentrations (0, 5, 10, and 20 mg/L) after 48 h exposure of 75 nm polystyrene nanoplastic on intestinal microbes, and oxidative stress parameters of freshwater crayfish, Procambarus clarkii. High-throughput sequencing analysis revealed the richness, diversity, and composition of intestinal microbiota in P. clarkii exposed to polystyrene nanoplastic. At the genus level, abundances of Lactobacillus, Faecalibaculum, Niveibacterium, and Candidatus Bacilloplasma were significantly different. The reduced abundance of Lactobacillus could affect the balance of intestinal microbes through quantitative disadvantage, which may lead to reduced immunity of P. clarkii. Streptococcus salivarius, Clostridium butyricum and Lachnospiraceae bacterium10-1 in intestinal tract reached maximum abundance at a polystyrene concentration of 20 mg/L. The increase in the number of some pathogenic bacteria may upset the balance of intestinal microorganisms through the number of dominance, and the decrease in the relative abundance of lactic acid bacteria. Probiotics, such as Lactobacillus salivarius, Lactobacillus murinus, Lactobacillus gasseri, Lactobacillus reuteri, Lactobacillus iners AB-1, and Lactobacillus crispatus in the intestinal tract reached the lowest value at a concentration of 10 mg/L. The reduced abundance of Lactobacillus can affect the balance of intestinal microbes through quantitative disadvantage, which may lead to reduced immunity in P. clarkii. At nanoplastic 10 mg/L, the relative abundance of intestinal pathogens increased, while the relative abundance of lactic acid bacteria and other probiotics decreased. With increases in nanoplastic concentrations, the values of glutathione (GSH), superoxide dismutase (SOD), acid phosphatase (ACP), lysozyme (LZM), alkaline phosphatase (AKP), peroxidase (POD), glutathione peroxidase (GPX), and protein carbonylation were significantly changed. Our data suggested that Lactobacillus may play an adjunctive role in the treatment of oxidative stress in P. clarkii exposed to 75 nm polystyrene. This study represents an important step towards a better understanding of the toxic effects of nanoplastics on aquatic crustaceans.

Red swamp crayfish Procambarus clarkii is an ecologically and economically important crustacean species. Here, based on a de novo assembly strategy combining PacBio with Hi-C sequencing, we presented a high quality chromosome-level P. clarkii genome. The assembled genome is 2.75 Gb in size with a contig N50 of 216.75 kb. Transposable elements (TEs) make up the largest fraction of the genome (~79.61%), and LINEs comprise the majority of the TEs. Frequent molting and rapid growth of the red swamp crayfish may be explained by the expansion of multiple gene families regarding growth or development. Phylogenetic analysis revealed that P. clarkii diverged from Portunus trituberculatus at 278–407 million years ago (Mya). PSMC analysis identified multiple bottleneck events of the P. clarkii population between 2 kaBP to 14 kaBP. The obtained P. clarkii genome should not only facilitate us understanding the development and evolution of the crayfish species, but also contribute to the genetic improvement in future breeding selections.

Hepatopancreatic necrosis disease (HPND) is a newly emerged disease in the Chinese mitten crab, and has caused significant economic damage to crab farmers. However, the exact pathogenesis of crab HPND has not been elucidated. To understand the metabolic shifts in the pathogenesis of the disease, we used LC-MS for metabolite profiling of the hepatopancreas of crabs with HPND. Diseased (DC) and healthy crabs (HC) from the ponds with disease occurrence, and healthy crabs (HHC) from adjacent ponds free from HPND, were analyzed. Histopathologic characteristics and potential pathogens in the hepatopancreas of the healthy and diseased crabs were preliminary investigated. Cellular damage or necrosis, including cell swelling, rupturing, vacuole formation and nuclear fragmentation were observed in diseased crabs. Pathogen screening revealed that, Hepatospora eriocheir, a parasite which was ever deemed to be the agent of the disease before, was unlikely the cause of HPND. Partial least squares discriminant analysis (PLS-DA) score plots revealed a significant metabolic difference between DC and HC in positive ionization modes (R2 = 0.96807, Q2 = 0.74558), while HC and HHC were grouped closely together. Fourty-five differential metabolites were identified and used for further functional pathway analyses. Two potential pathogenic factors, including fatty acid metabolic abnormalities and high concentrations of propamocarb (a widely used pesticide in vegetables), were found to be likely associated with HPND in the Chinese mitten crab. The identified metabolites and regulation pathways, and screening of potential pathogens in diseased crabs, should provide useful information for the prevention of the disease in the future.

lncrps25 is an intergenic long noncoding RNA (lncRNA), which is location close to rps25 (ribosomal protein S25) gene, is reported share high conserved sequence with NREP (neuronal regeneration-related protein) 3'-untranslated region. The function and mechanism of most of the lncRNA in embryo development remain largely unknown. In zebrafish, lncrps25 is widely expressed in the early embryonic stage and spinal cord during development. Morpholino (MO) knockdown of zebrafish lncrps25 exhibit locomotor behavior defects, caused by abnormal development of motor neurons. In addition, the defect of swimming ability and motor neurons could be recovery by microinject with lncrps25 RNA in lncrps25 morphants. By performing RNA sequencing and quantitative real-time polymerase chain reaction, we found that olig2 (oligodendrocyte transcription factor 2) messenger RNA (mRNA) was downregulated in lncrps25 morphants. Moreover, overexpression of olig2 mRNA in lncrps25 morphants partially rescued motor neurons development. Taken together, these results indicate that lncrps25 plays an essential role in the development of motor neurons in zebrafish.

As a type of pattern-recognition proteins (PRRs), C-type lectins (CTLs) perform important functions in non-self recognition and clearance of pathogens in innate immunity. In this study, a unique 2-transmembrane CTL (designated as Mn-2TM-cLec) with a single carbohydrate recognition domain (CRD) was isolated from Macrobrachium nipponense. The full-length cDNA of Mn-2TM-cLec consisted of 3265 bp with an 837 bp open reading frame encoding a protein with 278 amino acids. Mn-2TM-cLec was ubiquitously distributed in various tissues of normal prawn, particularly in the hemocytes, hepatopancreas, and gills. The expression of Mn-2TM-cLec was significantly up-regulated in the gills and hepatopancreas after the prawns were challenged with Staphylococcus aureus and Vibrio parahaemolyticus. RNA interference knock-down of Mn-2TM-cLec gene decreased the transcription levels of three antimicrobial peptides (anti-lipopolysaccharide factor (ALF) 1, ALF2, and Crustin (Crus) 1) after V. parahaemolyticus infection. The recombinant CRD of Mn-2TM-cLec could bind lipopolysaccharide, peptidoglycans, and diverse bacterial strains and agglutinate S. aureus and V. parahaemolyticus in a Ca2+-dependent manner. In addition, the rCRD enhanced the clearance of V. parahaemolyticus injected in prawns. In summary, Mn-2TM-cLec might act as a PRR to participate in the prawn immune defense against pathogens through its antimicrobial activity.

Background As one of the most popular and valuable commercial marine fishes in China and East Asian countries, the Chinese black porgy (Acanthopagrus schlegelii), also known as the blackhead seabream, has some attractive characteristics such as fast growth rate, good meat quality, resistance to diseases, and excellent adaptability to various environments. Furthermore, the black porgy is a good model for investigating sex changes in fish due to its protandrous hermaphroditism. Here, we obtained a high-quality genome assembly of this interesting teleost species and performed a genomic survey on potential genes associated with the sex-change phenomenon. Findings We generated 175.4 gigabases (Gb) of clean sequence reads using a whole-genome shotgun sequencing strategy. The final genome assembly is approximately 688.1 megabases (Mb), accounting for 93% of the estimated genome size (739.6 Mb). The achieved scaffold N50 is 7.6 Mb, reaching a relatively high level among sequenced fish species. We identified 19 465 protein-coding genes, which had an average transcript length of 17.3 kb. By performing a comparative genomic analysis, we found 3 types of genes potentially associated with sex change, which are useful for studying the genetic basis of the protandrous hermaphroditism. Conclusions We provide a draft genome assembly of the Chinese black porgy and discuss the potential genetic mechanisms of sex change. These data are also an important resource for studying the biology and for facilitating breeding of this economically important fish.

Seaweeds are some of the largest producers of biomass in the marine environment and are rich in bioactive compounds that are often used for human and animal health. Porphyran and carrageenan are natural compounds derived from red seaweeds. The former is a characteristic polysaccharide of Porphyra, while the latter is well known from Chondrus, Gigartina, and various Eucheuma species, all in Rhodophyceae. The two polysaccharides have been found to have anti-cancer activity by improving immunity and targeting key apoptotic molecules and therefore deemed as potential chemotherapeutic or chemopreventive agents. This review attempts to review the current study of anti-cancer activity and the possible mechanisms of porphyran and carrageenan derived from red seaweeds to various cancers, and their cooperative actions with other anti-cancer chemotherapeutic agents is also discussed.

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.

In this study, the complete mitochondrial genome of Sinobdella sinensis was reported. The circular genome is 16,540 bp in length and consists of 13 protein-coding genes, 22 tRNA genes, 2 ribosomal RNA genes, and 1 control region. The overall nucleotide composition was 30.0% A, 26.5% T, 28.7% C, and 14.8% G, with an A + T bias of 56.5%. The gene composition and the structural arrangement of the S. sinensis complete mtDNA were identical to most other vertebrates. The molecular data here we presented could play a useful role to study the evolutionary relationships and population genetics of Mastacembelidae fish.

In the present study, the complete mitogenome sequence of Gnathopogon imberbis is determined using PCR amplification and DNA sequencing, which contains 13 protein-coding genes, 22 tRNA genes, 2 rRNA genes and a non-coding control region with the total length of 16,598 bp. Except for eight tRNA and ND6 genes, all other mitochondrial genes are encoded on the H-strand. The codon usage followed the typical vertebrate mitochondrial pattern (ATG or GTG for start codon and TAA or TAG for stop codon). The overall nucleotide composition was 30.0% A, 27.0% T, 25.8% C and 17.2% G, with an A + T bias of 57.0%. The complete mitochondrial genome sequence will be useful for phylogenetic analysis and studies of population genetics of G. imberbis.