Water decoction of Astragalus membranaceus enhances cellular immune response and disease resistance in spotted maigre

The effect of dietary Chinese herb Astragalus membranaceus on the cellular immune response of spotted maigre (Nibea albifiora) was investigated. 300 spotted maigre with an average initial weight of 49.6 ± 5.5 g were selected and fed with different levels of water decoction of A. membranaceus (WDA) (0, 0.5, 1.0, 2.0 and 4.0%) for 4 weeks. Non-specific immune responses were measured after 0, 3, 7, 14, 21, 28 days of feeding. We then injected control and WDA treated fish with an intraperitoneal injection of Vibrio vulnificus, and recorded their mortality rate for 7 days post-infection. The results showed that the phagocytic index of phagocytes was significantly higher in 2% WDA treated group as compared to other groups (P<0.05). Whereas, the percentages of phagocytes were significantly higher in 0.5, 1.0 and 2.0% WDA groups as compared to 4.0% WDA and control groups (P<0.05). But lysozyme activities were significantly higher in the Astragalus-fed groups as compared to the control group (P≤0.05), and 2% group was the highest. Furthermore, 2% WDA-fed fish were significantly protected against V. vulnificus infestation (73.3% survival) as compared to 63.3, 53.3 and 36.7% survival in the 1 and 0.5% WDA-fed and control, respectively. In conclusion, dietary WDA may effectively enhance cellular immune response and disease resistance in spotted maigre against V. vulnificus.Key words: Astragalus membranaceus, spotted maigre, non-specific immune response, Vibrio vulnificus

Annealing tunable charge density wave order in a magnetic kagome material FeGe

In the magnetic kagome metal FeGe, a charge density wave (CDW) order emerges inside the antiferromagnetic phase, providing a fertile playground to investigate the interplay between charge and magnetic orders. Here, we demonstrate that the CDW order, as well as magnetic properties, can be reversibly tuned on a large scale through post-growth annealing treatments. The antiferromagnetic and CDW transitions vary systematically as functions of both the temperature and the time period of annealing. Long-range CDW order with a maximum $T_{\mathrm{CDW}}$ and a minimum $T_{\mathrm{N}}$ can be realized in crystals annealed at \SI{320}{\degreeCelsius} for over 48 h. Using magnetization and magnetostrictive coefficient measurements, it is found that the CDW transition is rather stable against an external magnetic field and spin-flop transition. On the other hand, the critical field for spin-flop transition is significantly reduced in the long-range ordered CDW phase. Our results indicate that the CDW in FeGe is immune to variations in magnetic orders, while the magnetocrystalline anisotropy energy and the corresponding magnetic ground state can be altered significantly by the charge order. These findings provide crucial clues for further investigation and a better understanding of the nature of the CDW order in FeGe.Comment: 8 pages, 4 figure

Polysaccharides, Saponins, and Water Decoction of Astragalus membranaceus Significantly Enhance the Non-Specific Immune Response of Spotted Maigre (Nibea albiflora)

The effects of polysaccharides, saponins, and water decoction of the Chinese herb Astragalus membranaceus on the immune response of spotted maigre (Nibea albiflora) were investigated. Fish with an average initial weight of 49.6±5.5 g were fed a diet containing 2% extract for four weeks. The lysozyme and phagocytic activities of the fish were determined and compared with those of control fish fed an unsupplemented feed on days 0, 3, 7, 14, 21, and 28. Both activities were significantly higher in groups fed the Astragalus extract than in the control group (p0.05). Most important, the Astragalus-fed groups were significantly protected against Vibrio vulnificus challenge compared to the control group (p<0.01). Our results indicatd that polysaccharides and saponins are main active components of Astragalus extracts and can enhance the non-specific immune response in spotted maigre

Transcriptome analysis of sex-related genes in the blood clam Tegillarca granosa.

Blood clams (Tegillarca granosa) are one of the most commercial shellfish in China and South Asia with wide distribution in Indo-Pacific tropical to temperate estuaries. However, recent data indicate a decline in the germplasm of this species. Furthermore, the molecular mechanisms underpinning reproductive regulation remain unclear and information regarding genetic diversity is limited. Understanding the reproductive biology of shellfish is important in interpreting their embryology development, reproduction and population structure. Transcriptome sequencing (RNA-seq) rapidly obtains genetic sequence information from almost all transcripts of a particular tissue and currently represents the most prevalent and effective method for constructing genetic expression profiles.Non-reference RNA-seq, an Illumina HiSeq2500 Solexa system, and de novo assembly were used to construct a gonadal expression profile of the blood clam. A total of 63.75 Gb of clean data, with at least 89.46% of Quality30 (Q30), were generated which was then combined into 214,440 transcripts and 125,673 unigenes with a mean length of 1,122.63 and 781.30 base pairs (bp). In total, 27,325 genes were annotated by comparison with public databases. Of these, 2,140 and 2,070 differentially expressed genes (DEGs) were obtained (T05 T08 vs T01 T02 T04, T06 T07 vs T01 T02 T04; in which T01-T04 and T05-T08 represent biological replicates of individual female and male clams, respectively) and classified into two groups according to the evaluation of biological replicates. Then 35 DEGs and 5 sex-related unigenes, in other similar species, were investigated using qRT-PCR, the results of which were confirmed to data arising from RNA-seq. Among the DEGs, sex-related genes were identified, including forkhead box L2 (Foxl2), sex determining region Y-box (Sox), beta-catenin (β-catenin), chromobox homolog (CBX) and Sex-lethal (Sxl). In addition, 6,283 simple sequence repeats (SSRs) and 614,710 single nucleotide polymorphisms (SNPs) were identified from the RNA-seq results.This study provided the first complete gonadal transcriptome data for the blood clam and allowed us to search many aspects of gene sequence information, not limited to gender. This data will improve our understanding of the transcriptomics and reproductive biology of the blood clam. Furthermore, molecular markers such as SSRs and SNPs will be useful in the analysis of genetic evolution, bulked segregant analysis (BSA) and genome-wide association studies (GWAS). Our transcriptome data will therefore provide important genetic information for the breeding and conservation of germplasm

Seawater carbonate chemistry and sperm motility of Tegillarca granosavia

Since the industrial revolution, massive amount of anthropogenic carbon dioxide (CO2) have been generated to elevate the atmospheric CO2 concentration. Some anthropogenic CO2 have been absorbed by the ocean to cause “ocean acidification” (OA). Although the negative impacts of OA on sperm motility are increasingly found in various marine invertebrate species, the cellular and molecular mechanisms for these effects are still poorly understood. This study investigated the effect of OA (pH7.8 and 7.4) on sperm motility and energy supplying pathway in blood clam Tegillarca granosa. The results showed that the sperm swimming speed reduced significantly in acidified seawater. Since the adenosine triphosphate (ATP) level of sperm is closely related to its motility, we analyzed the sperm ATP content and activities of key enzymes during ATP synthesis under different OA scenarios. OA treatments significantly reduced ATP content as well as activities of 6-phosphofructokinase and pyruvate kinase in the sperm of T. granosa. The sperm Ca2+-ATPase of various animals has been reported to regulate sperm motility. Therefore, we explored the Ca2+-ATPase activity of T. granosa sperm under OA treatment. The results found that Ca2+-ATPase activities in the sperm of T. granosa were significantly declined under OA scenarios. In conclusion, these results suggested that OA could constrain sperm motility through inhibiting ATP synthesis and disturbing intracellular Ca2+ regulation

Ocean acidification increases cadmium accumulation in marine bivalves: a potential threat to seafood safety

To date, the effects of ocean acidification on toxic metals accumulation and the underlying molecular mechanism remains unknown in marine bivalve species. In the present study, the effects of the realistic future ocean pCO2 levels on the cadmium (Cd) accumulation in the gills, mantle and adductor muscles of three bivalve species, Mytilus edulis, Tegillarca granosa, and Meretrix meretrix, were investigated. The results obtained suggested that all species tested accumulated significantly higher Cd (p<0.05) in the CO2 acidified seawater during the 30 days experiment and the health risk of Cd (based on the estimated target hazard quotients, THQ) via consumption of M. meretrix at pH 7.8 and 7.4 significantly increased 1.21 and 1.32 times respectively, suggesting a potential threat to seafood safety. The ocean acidification-induced increase in Cd accumulation may have occurred due to (i) the ocean acidification increased the concentration of Cd and the Cd2+/Ca2+ in the seawater, which in turn increased the Cd influx through Ca channel; (ii) the acidified seawater may have brought about epithelia damage, resulting in easier Cd penetration; and (iii) ocean acidification hampered Cd exclusion

Benzo[a]pyrene exposure under future ocean acidification scenarios weakens the immune responses of blood clam, Tegillarca granosa

Persistent organic pollutants (POPs) are known to converge into the ocean and accumulate in the sediment, posing great threats to marine organisms such as the sessile bottom burrowing bivalves. However, the immune toxicity of POPs, such as B[a]P, under future ocean acidification scenarios remains poorly understood to date. Therefore, in the present study, the impacts of B[a]P exposure on the immune responses of a bivalve species, Tegillarca granosa, under present and future ocean acidification scenarios were investigated. Results obtained revealed an increased immune toxicity of B[a]P under future ocean acidification scenarios in terms of reduced THC, altered haemocyte composition, and hampered phagocytosis, which may attribute to the synergetic effects of B[a]P and ocean acidification. In addition, the gene expressions of pathogen pattern recognition receptors (TLR1, TLR2, TLR4, TLR6), pathway mediators (TRAF6, TAK1, TAB2, IKKalpha and Myd88), and effectors (NF-kB) of the important immune related pathways were significantly down-regulated upon exposure to B[a]P under future ocean acidification scenarios. Results of the present study suggested an increased immune toxicity of B[a]P under future ocean acidification scenarios, which will significantly hamper the immune responses of T. granosa and subsequently render individuals more susceptible to pathogens challenges

Seawater carbonate chemistry and burrowing behaviour, Ca2+/Mg2+-ATPase activity, metabolism, and gene expression of a bivalve species, Sinonovacula constricta

Although the effect of ocean acidification on fertilization success of marine organisms is increasingly well documented, the underlying mechanisms are not completely understood. The fertilization success of broadcast spawning invertebrates depends on successful sperm-egg collisions, gamete fusion, and standard generation of Ca2+oscillations. Therefore, the realistic effects of future ocean pCO2 levels on these specific aspects of fertilization of Tegillarca granosa were investigated in the present study through sperm velocity trials, fertilization kinetics model analysis, and intracellular Ca2+assays, respectively. Results obtained indicated that ocean acidification significantly reduced the fertilization success of T. granosa, which could be accountable by (i) decreased sperm velocity hence reducing the probability for sperm-egg collisions; (ii) lowered probability of gamete fusion for each gamete collision event; and (iii) disrupted intracellular Ca2+ oscillations

Crosslinking kinetics of polycarbosilane precursor in ozone atmosphere and the formation mechanism of continuous hollow SiC fiber

Crosslinking kinetics of polycarbosilane precursor in ozone atmosphere and the formation mechanism of continuous hollow SiC fibe