Lin Yao

Characterization of antimicrobial resistance of Vibrio parahaemolyticus from cultured sea cucumbers (Apostichopus japonicas)

This study was aimed to evaluate the antimicrobial resistance and molecular resistance mechanisms of 87 Vibrio parahaemolyticus isolates from cultured sea cucumbers (Apostichopus japonicus). The results showed that all isolates were resistant to ampicillin and cephazolin, fewer of them were resistant to streptomycin (43·7%), cefuroxime sodium (18·4%), tetracycline (4·6%), sulphamethoxazole/trimethoprim (2·3%) and four quinolones (2·3%). More than half (56·2%) of the isolates displayed multiple resistance to at least three antimicrobials. The resistance genes were detected in all antimicrobial‐resistant isolates except two tetracycline‐resistant isolates. Among all these tested resistance genes, blaTEM, sul2, strA and strB were predominant, and none of blaSHV, blaCTX‐M, blaOXA, sul1, sul3, tetA, tetM and tetQ genes was detected. Point mutations were found in quinolone resistance‐determining regions of gyrA and parC genes in quinolone‐resistant isolates. All isolates harboured class 1 integrons but only one carried gene cassette without any resistance genes, and none of them was positive to class 2, 3 integrons and SXT constins. These results indicate that the antimicrobial‐resistant V. parahaemolyticus isolates from sea cucumbers and resistance genes could be potential risks to public health or other environments.

Protective Effect of Edible Marine Algae, Laminaria japonica and Porphyra haitanensis, on Subchronic Toxicity in Rats Induced by Inorganic Arsenic

Arsenic, a potent environmental toxic agent, causes various hazardous effects on human health. This study was performed to evaluate the protective effects of edible marine algae, Laminaria japonica and Porphyra haitanensis, on subchronic stress of rats induced by arsenic trioxide (As2O3). The co-treatment of marine algae could slightly increase the growth rates of body weights compared to the As2O3-treated group. The marine algae application restored liver and renal function by preventing the increment in the activities of alanine transaminase and alkaline phosphatase, and the levels of total protein, blood urea nitrogen, and creatinine. The increase in the contents of total cholesterol, triglyceride, and low density lipoprotein cholesterol, and decrease in the contents of high density lipoprotein cholesterol were observed in algae co-treated groups which indicated that marine algae could reverse the abnormal lipid metabolisms induced by arsenic. Moreover, these algae could protect the rats from lipid peroxidation by restoring the depletion of superoxide dismutase and glutathione peroxidase activities and sulfhydryl group contents, and lowering the enhanced malondialdehyde contents. Therefore, evidences indicate that L. japonica and P. haitanensis can serve as an effective regimen for treating arsenic poisoning.

Comparative transcriptomics reveals genes involved in metabolic and immune pathways in the digestive gland of scallop Chlamys farreri following cadmium exposure

Chlamys farreri is an economically important mollusk that can accumulate excessive amounts of cadmium (Cd). Studying the molecular mechanism of Cd accumulation in bivalves is difficult because of the lack of genome background. Transcriptomic analysis based on high-throughput RNA sequencing has been shown to be an efficient and powerful method for the discovery of relevant genes in non-model and genome reference-free organisms. Here, we constructed two cDNA libraries (control and Cd exposure groups) from the digestive gland of C. farreri and compared the transcriptomic data between them. A total of 227 673 transcripts were assembled into 105 071 unigenes, most of which shared high similarity with sequences in the NCBI non-redundant protein database. For functional classification, 24 493 unigenes were assigned to Gene Ontology terms. Additionally, EuKaryotic Ortholog Groups and Kyoto Encyclopedia of Genes and Genomes analyses assigned 12 028 unigenes to 26 categories and 7 849 unigenes to five pathways, respectively. Comparative transcriptomics analysis identified 3 800 unigenes that were differentially expressed in the Cd-treated group compared with the control group. Among them, genes associated with heavy metal accumulation were screened, including metallothionein, divalent metal transporter, and metal tolerance protein. The functional genes and predicted pathways identified in our study will contribute to a better understanding of the metabolic and immune system in the digestive gland of C. farreri. In addition, the transcriptomic data will provide a comprehensive resource that may contribute to the understanding of molecular mechanisms that respond to marine pollutants in bivalves.

Discovery of genes associated with cadmium accumulation from gill of scallop Chlamys farreri based on high-throughput sequencing

Chlamys farreri is an important economic mollusk and is able to accumulate cadmium (Cd) excessively. Two cDNA libraries from gill of C. farreri which were Cd treated or not were generated based on the Illumina sequencing platform in order to identify differentially expressed genes (DEGs) associated with cadmium accumulation. The analysis of comparative transcriptomics identified 82,800 unigenes and 128 differentially expressed genes. Of these, 8 of the most significant DEGs were verified by real-time PCR, showing consistent trends in expression patterns between the two techniques. KEGG pathways analysis revealed that 37 associated processes were highly enriched. A set of key DEGs were identified that may play important roles in cadmium exposure. Our work presents an overview of gene expression change during cadmium exposure to C. farreri and identifies a series of candidate genes and pathways for further research on the molecular mechanisms of cadmium accumulation.

Antimicrobial resistance, virulence and genetic relationship of Vibrio parahaemolyticus in seafood from coasts of Bohai Sea and Yellow Sea, China

Vibrio parahaemolyticus is an important foodborne pathogen which commonly inhabits estuarine and marine environments and seafood. In the present study, 90 V. parahaemolyticus isolates from the main seafoods from three coastal provinces surrounding Bohai Sea and Yellow Sea, China were analyzed to elucidate their antimicrobial resistance, virulence and genetic relationship by multilocus sequence typing (MLST). The results showed that the virulence genes tdh and trh were detected in one isolate and five isolates respectively. Most of isolates showed resistance to ampicillin (86/90) and cephazolin (75/90). Some isolates were resistant to amikacin (27/90), cefuroxime sodium (18/90), tetracycline (16/90), sulphamethoxazole/trimethoprim (16/90) and streptomycin (13/90). Forty isolates (44.4%) possessed multiple antimicrobial resistance to at least three antimicrobials. The V. parahaemolyticus population was composed of 68 sequence types, of which 41 were novel to the pubMLST database, displaying a high level of genetic diversity. The phylogenetic relatedness of V. parahaemolyticus isolates was irrelevant to the collection sources. Moreover, there were no associations of antimicrobial resistance and trh positive virulence with genetic population of V. parahaemolyticus isolates. These results indicated that the diversity of antimicrobial-resistant or pathogenic V. parahaemolyticus isolates from coasts of Bohai Sea and Yellow Sea, China could pose a potential risk to human health.

Histopathological Liver and Testis Alterations in Male Half-Smooth Tongue Sole (Cynoglossus semilaevis) Exposed to Endocrine Disruptors

ABSTRACT Li, F.; Yao, L.; Sun, W.; Jiang, Y.; Li, Z., and Zhai, Y., 2017. Histopathological liver and testis alterations in male half-smooth tongue sole (Cynoglossus semilaevis) exposed to endocrine disruptors. Endocrine-disrupting chemicals are a class of xenobiotics that may interfere with the function of the endocrine system. The adverse effects of these substances can be identified through pathology. In this research, the effects of bisphenol A (BPA) or 17β-estradiol (E2) exposure on the liver and testis of Cynoglossus semilaevis were investigated. In particular, this research observed the pathological alterations in the liver (e.g., cellular swelling, hepatocyte adhesion, and vacuolation, etc.) and testis (e.g., cellular swelling, sperm deformation, and flagellum bending, etc.). Results of the investigation revealed that exposure dose and response indicators are correlated with each other, and BPA or E2 exposure at different doses induces some degree of damage to C. semilaevis tissues on a histopathological level. Accordingly, this research provides a window for developing C. semilaevis as a model of marine fish in determining the effects of other kinds of pollutant exposure on the aquatic ecosystem and on humans.