Showing papers by "Jimei University published in 2015"

Prebiotics and Fish Immune Response: A Review of Current Knowledge and Future Perspectives

Abstract: It is now a well-documented fact that there is a distinct relation between fish nutrition and health status. Intensification of aquaculture practice to meet market demand causes stress and elevates the risk of the disease outbreak. Therefore, provisions of proper diets as well as appropriate feeding regimens are of high importance in intensive aquaculture. Considering the negative impacts raised by prophylactic and therapeutic use of antibiotic in aquaculture, administration of dietary immunostimulant has been suggested as an alternative to antimicrobial agents. In this sense, functional dietary supplements, including pre-, pro- and synbiotic received increasing attention as an environment-friendly strategy for improving fish health. During the past years, administration of prebiotics in the diet of different fish species revealed promising results in immune response. In the present review article, the topic of the administration of dietary prebiotics in aquaculture is addressed with a special focus on re...

Phylogenetic shifts of bacterioplankton community composition along the Pearl Estuary: the potential impact of hypoxia and nutrients

Abstract: The significance of salinity in shaping bacterial communities dwelling in estuarine areas has been well documented. However, the influences of other environmental factors such as dissolved oxygen and nutrients in governing bacterioplankton communities inhabited in local estuarine regions remain elusive. Here, bacterioplankton community structure of surface and bottom waters from eight sites along Pearl Estuary were characterized with 16S rRNA genes pyrosequencing. The bacterioplankton community dendrogram partitioned the samples into three groups, i.e., whole water column of freshwater sites, surface water of saltwater sites and bottom water of saltwater sites. In the saltwater sites, Synechococcus dominated the surface water while Oceanospirillales, SAR11 and SAR406 were prevalent in the bottom water. Betaproteobacteria was abundant in the freshwater sites, with no significant difference between water layers. Moreover, occurrence of phylogenetic shifts in taxa affiliated to the same clade was also detected. Dissolved oxygen explained most of the bacterial community variation in the redundancy analysis targeting only freshwater sites, whereas nutrients and salinity explained most of the variation across all the samples in Pearl Estuary. Methylophilales (mainly PE2 clade) was positively correlated to dissolved oxygen, whereas Rhodocyclales (mainly R.12up clade) was negatively correlated. Moreover, high nutrient inputs to the freshwater area of Pearl Estuary have shifted the bacterial communities towards copiotrophic groups, such as Sphingomonadales. The present study provides a clear outline of bacterioplankton communities in two regions of a subtropical estuary and demonstrates that the overall nutrients and freshwater hypoxia play important roles in determining bacterioplankton compositions

Mechanism of charge transfer and its impacts on Fermi-level pinning for gas molecules adsorbed on monolayer WS2.

Abstract: Density functional theory calculations were performed to assess changes in the geometric and electronic structures of monolayer WS2 upon adsorption of various gas molecules (H2, O2, H2O, NH3, NO, NO2, and CO). The most stable configuration of the adsorbed molecules, the adsorption energy, and the degree of charge transfer between adsorbate and substrate were determined. All evaluated molecules were physisorbed on monolayer WS2 with a low degree of charge transfer and accept charge from the monolayer, except for NH3, which is a charge donor. Band structure calculations showed that the valence and conduction bands of monolayer WS2 are not significantly altered upon adsorption of H2, H2O, NH3, and CO, whereas the lowest unoccupied molecular orbitals of O2, NO, and NO2 are pinned around the Fermi-level when these molecules are adsorbed on monolayer WS2. The phenomenon of Fermi-level pinning was discussed in light of the traditional and orbital mixing charge transfer theories. The impacts of the charge transfer mechanism on Fermi-level pinning were confirmed for the gas molecules adsorbed on monolayer WS2. The proposed mechanism governing Fermi-level pinning is applicable to the systems of adsorbates on recently developed two-dimensional materials, such as graphene and transition metal dichalcogenides.

The protective effects of berry-derived anthocyanins against visible light-induced damage in human retinal pigment epithelial cells

Abstract: BACKGROUND Studies have shown that anthocyanins (ACNs) in berries contribute to eye health. However, information on the relationship between the chemical structures and visual functions of ACNs is scarce. This study investigated the protection effects of ACNs with different structures against visible light-induced damage in human retinal pigment epithelial (RPE) cells. RESULTS Four ACNs with different aglycones, namely, pelargonidin-3-glucoside (Pg-3-glu), cyanidin-3-glucoside (Cy-3-glu), delphinidin-3-glucoside, and malvidin-3-glucoside (Mv-3-glu), were isolated from three berries (blueberry, blackberry and strawberry). Of these ACNs, Cy-3-glu exhibited the highest reactive oxygen species inhibitory capacity in RPE cells, with 40 µg mL−1 Cy-3-glu showing a ROS clearance of 57.5% ± 4.2%. The expression of vascular endothelial growth factor levels were significantly (P < 0.05) down-regulated by Cy-3-glu and Mv-3-glu in a visible light-induced damage RPE cell model. Cy-3-glu and Pg-3-glu treatments significantly (P < 0.05) inhibited the increase in β-galactosidase during the RPE cell ageing caused by visible light exposure. CONCLUSION Our findings suggest that the biological properties of different ACNs significantly vary. Cy-3-glu, which contains an ortho hydroxyl group in its B ring, possibly exerts multiple protective effects (antioxidant, anti-angiogenic and anti-ageing) in RPE cells. Therefore, Cy-3-glu may prove useful as a prophylactic health food for the prevention of retinal diseases. © 2014 Society of Chemical Industry

Biotransformation of tea catechins using Aspergillus niger tannase prepared by solid state fermentation on tea byproduct

Abstract: A tannase that was prepared from Aspergillus niger by a solid-state fermentation on tea byproducts was investigated to transform the catechins in tea infusion. The tannase could effectively hydrolyze epigallocatechin gallate (EGCG), gallocatechin gallate (GCG) and epicatechin gallate (ECG) of tea infusion, which showed pH values ranged from 4.8 to 5.3 during the tannase treatment. The enzyme was active and stable within pH 3.0–7.0 and 4–60 °C. The enzyme had Kms of 14.89 mmol/L, 16.13 mmol/L and 3.57 mmol/L for EGCG, GCG and ECG, respectively in pure solutions. However, the hydrolysis of individual EGCG, GCG and ECG in the tea infusion showed different kinetic parameters from those in pure solutions. The transformation of EGCG was the dominant reaction in tea infusion. After the tannase treatment, tea infusion was detected to have significant increases in the clarity and activities for scavenging 2, 2′-azino-bis (3-ethylbenzothiazoline-6-sulfonate) (ABTS) radical, 2, 2-diphenyl-1-picryl-hydrazyl (DPPH) radical and hydroxyl radical. The results indicated the tannase was effective to transform the catechins, which could be possibly used for commercial extraction of catechins. In addition, the results suggested it is more desirable to follow the dynamic model to control the tannase treatment of tea infusion for a better processing.

Purification, Characterization, and Analysis of the Allergenic Properties of Myosin Light Chain in Procambarus clarkii.

Abstract: Myosin light chain (MLC) plays a vital role in cell and muscle functions and has been identified as an allergen in shrimp. In this study, MLC with a molecular mass of 18 kDa was purified from crayfish (Procambarus clarkii) muscle. Its physicochemical characterization showed that the purified MLC is a glycoprotein with 4.3% carbohydrate, highly stable to heat, acid-alkali, and digestion, and weakly retains IgE-binding activity when its secondary structure was altered. Serological assays suggested that conformational epitopes predominate over linear epitopes in the purified MLC. Two isoforms of the MLC gene (MLC1 and MLC2) were cloned, and the purified MLC was identified as MLC1. Analysis of the secondary and tertiary structures of the MLCs indicated that MLC1 has four conformational epitopes and three linear epitopes, whereas MLC2 had a major conformational epitope and three linear epitopes. These results are significant for understanding hypersensitization of humans to crayfish.

Functional Marker Detection and Analysis on a Comprehensive Transcriptome of Large Yellow Croaker by Next Generation Sequencing

Abstract: Large yellow croaker (Larimichthys crocea) is an important economic fish in China and Eastern Asia. Because of the exhaustive fishing and overdense aquaculture, the wild population and the mariculture of the species are facing serious challenges on germplasm degeneration and susceptibility to infectious disease agents. However, a comprehensive transcriptome from multi-tissues of the species has not been reported and functional molecular markers have not yet been detected and analyzed. In this work, we applied RNA-seq with the Illumina Hiseq2000 platform for a multi-tissue sample of large yellow croaker and assembled the transcriptome into 88,103 transcripts. Of them, 52,782 transcripts have been successfully annotated by nt/nr, InterPro, GO and KEGG database. Comparing with public fish proteins, we have found that 34,576 protein coding transcripts are shared in large yellow croaker with zebrafish, medaka, pufferfish, and stickleback. For functional markers, we have discovered 1,276 polymorphic SSRs and 261, 000 SNPs. The functional impact analysis of SNPs showed that the majority (~75%) of small variants cause synonymous mutations in proteins, followed by variations in 3' UTR region. The functional enrichment analysis illuminated that transcripts involved in DNA bindings, enzyme activities, and signal pathways prominently exhibit less single-nucleotide variants but genes for the constituent of the muscular tissue, the cytoskeleton, and the immunity system contain more frequent SNP mutations, which may reflect the structural and functional selections of the translated proteins. This is the first work for the high-throughput detection and analysis of functional polymorphic SSR and SNP markers in a comprehensive transcriptome of large yellow croaker. Our study provides valuable transcript sequence and functional marker resources for the quantitative trait locus (QTL) identification and molecular selection of the species in the research community.

Molecularly imprinted polymers for extraction of malachite green from fish samples prior to its determination by HPLC

Abstract: Molecularly imprinted polymer (MIP) particles for malachite green (MG) were prepared by emulsion polymerization using methacrylic acid as the functional monomer, ethylene glycol dimethacrylate as the cross-linker, and a combination of Span-80 and Tween-80 as an emulsifier. The MIP particles were characterized by SEM micrographs and FT-IR spectra. Their binding capacity for MG was evaluated based on kinetic and isothermal adsorption experiments and compared to non-imprinted polymer particles. Analytical figures of merit include an adsorption equilibrium time of 15 min, an adsorption capacity of 1.9 mg∙g‾1 in acetonitrile-water (20:80), and an imprinting factor of 1.85. The MIP particles were successfully applied to the extraction of MG from fish samples spiked with MG and the other interfering substances prior to its determination of MG by HPLC. Spiked samples gave recoveries of MG that ranged from 86 to 104 %, much higher than that of the other interfering substance.

A study on the microstructure and tribological behavior of cold-sprayed metal matrix composites reinforced by particulate quasicrystal

Abstract: In the present study, mechanical blends of AlCuFeB quasicrystal and tin bronze powders were deposited by cold spray process to obtain metal matrix composites (MMCs) reinforced with quasicrystalline particulates. The influences of the incorporation of quasicrystal particles on the particle deposition behavior, microstructure and microhardness of the composite coatings were investigated. In order to evaluate the influence of reinforcing quasicrystal phase on the tribological behavior of the coatings, ball-on-disc sliding tribological tests were conducted in an ambient condition. The results showed that the incorporation of quasicrystal particles reduced the porosity and increased the microhardness of the composite coatings. At the same time, a reduction of the friction coefficient and an increase of wear rate were found. Wear mechanisms were discussed and correlated to the microstructure and microhardness of coatings.

Gene map of large yellow croaker ( Larimichthys crocea ) provides insights into teleost genome evolution and conserved regions associated with growth

Abstract: The genetic map of a species is essential for its whole genome assembly and can be applied to the mapping of important traits. In this study, we performed RNA-seq for a family of large yellow croakers (Larimichthys crocea) and constructed a high-density genetic map. In this map, 24 linkage groups comprised 3,448 polymorphic SNP markers. Approximately 72.4% (2,495) of the markers were located in protein-coding regions. Comparison of the croaker genome with those of five model fish species revealed that the croaker genome structure was closer to that of the medaka than to the remaining four genomes. Because the medaka genome preserves the teleost ancestral karyotype, this result indicated that the croaker genome might also maintain the teleost ancestral genome structure. The analysis also revealed different genome rearrangements across teleosts. QTL mapping and association analysis consistently identified growth-related QTL regions and associated genes. Orthologs of the associated genes in other species were demonstrated to regulate development, indicating that these genes might regulate development and growth in croaker. This gene map will enable us to construct the croaker genome for comparative studies and to provide an important resource for selective breeding of croaker.