The Pacific oyster, Crassostrea gigas, has developed special mechanisms to regulate its osmotic balance to adapt to fluctuations of salinities in coastal zones. To understand the oyster's euryhaline ...adaptation, we analyzed salt stress effectors metabolism pathways under different salinities (salt 5, 10, 15, 20, 25, 30 and 40 for 7 days) using transcriptome data, physiology experiment and quantitative real-time PCR.
Transcriptome data uncovered 189, 480, 207 and 80 marker genes for monitoring physiology status of oysters and the environment conditions. Three known salt stress effectors (involving ion channels, aquaporins and free amino acids) were examined. The analysis of ion channels and aquaporins indicated that 7 days long-term salt stress inhibited voltage-gated Na(+)/K(+) channel and aquaporin but increased calcium-activated K(+) channel and Ca(2+) channel. As the most important category of osmotic stress effector, we analyzed the oyster FAAs metabolism pathways (including taurine, glycine, alanine, beta-alanine, proline and arginine) and explained FAAs functional mechanism for oyster low salinity adaptation. FAAs metabolism key enzyme genes displayed expression differentiation in low salinity adapted individuals comparing with control which further indicated that FAAs played important roles for oyster salinity adaptation. A global metabolic pathway analysis (iPath) of oyster expanded genes displayed a co-expansion of FAAs metabolism in C. gigas compared with seven other species, suggesting oyster's powerful ability regarding FAAs metabolism, allowing it to adapt to fluctuating salinities, which may be one important mechanism underlying euryhaline adaption in oyster. Additionally, using transcriptome data analysis, we uncovered salt stress transduction networks in C. gigas.
Our results represented oyster salt stress effectors functional mechanisms under salt stress conditions and explained the expansion of FAAs metabolism pathways as the most important effectors for oyster euryhaline adaptation. This study was the first to explain oyster euryhaline adaptation at a genome-wide scale in C. gigas.
Aiming at the problem that the effectiveness of impulse feature enhancement (IFE) depends on the duration of high-level (or low-level)
K
and the number of high-level
L
, we regard a segmented impulse ...norm as the fitness function and combine it with the whale optimization algorithm to select the optimal parameters adaptively. Time-frequency joint noise reduction (TFJNR) is also proposed to suppress the noise components in the signal. Simulation and experimental results of rolling bearings indicate that the proposed algorithm can rapidly select the optimal parameters
K
and
L
to ensure the performance of IFE, while TFJNR has the ability to suppress the noise components in the signal. Fast kurtogram, empirical mode decomposition, and fast spectral correlation are also used for comparison. The results highlight the performance of the proposed algorithm.
The Pacific oyster Crassostrea gigas is an important fishery resource that is sensitive to temperature fluctuations. Thus, it has evolved a protection mechanism against heat stress by increasing the ...expression of the gene coding for heat shock protein (HSP) 70 under elevated temperatures. In other animals, heat shock response is a transcriptional response driven by the heat shock transcription factor 1 (HSF1) and thermal stress can trigger HSP70 expression to protect the organism via HSF1. However, the regulatory relationship between HSF1 and HSP remains unclear in Pacific oyster. Therefore, in the present study, we examined the transcriptomic response of several to thermal stress following HSF1 interference.
We identified 150 genes responsive to heat shock including seven HSP genes, six of which belonging to the group of 17 HSP genes enriched in response to heat shock, according to weighted gene co-expression network analysis (WGCNA). The other gene was enriched in the module correlated with HSF1 interference. In addition, we found 48 and 47 genes that were upregulated and downregulated by HSF1 in response to heat shock, respectively. In the upregulated genes, we identified one HSP70 potentially regulated by HSF1 in response to heat shock. Furthermore, based on differentially expressed genes and WGCNA analyses, we found that the hypoxia signaling pathway was enriched under heat shock conditions. Five genes were then selected to detect dynamic changes through time. The results suggested that gene expression was correlated with HSF1 expression. The regulation of HSP70 by HSF1 was preliminarily confirmed by binding site predictions and by a dual luciferase assay.
Our results revealed that the expression of HSP70 and HSP20 was initially triggered after 2 h of heat shock, and one of the HSP70 genes was potentially regulated by HSF1. From these results, it is evident that not all heat-inducible genes were triggered simultaneously in response to heat shock stress. Overall, the results revealed a possible HSF1-HSP regulatory relationship in Pacific oyster, providing valuable information on the mechanisms of thermal tolerance in this commercially important oyster.
2,4-Dihydroxybenzophenone is the most widely used molecule in the benzophenone group of UV absorbers. It is known that the UV absorption ability is dependent on the substituents. Numerous studies ...have shown that the strength of intramolecular hydrogen bonds is the main factor affecting this type of UV absorber. However, the effect of substituents on the formation and nature of the hydrogen bonds has not been well studied. In this work, the effect of the type of substituent and the substitution position on the absorption intensity of 2,4-dihydroxybenzophenone molecules is verified both experimentally and theoretically. The effect of substituents on the intramolecular hydrogen bonding of 2,4-dihydroxybenzophenone was investigated by DFT calculations. The results indicate that the addition of different substituents leads to various changes in the strength of the hydrogen bonding in 2,4-dihydroxybenzophenone. On the X-substitution site or the Y-substitution site, halogen groups and electron-absorbing groups such as -CN and -NO
increase the strength of the hydrogen bond, while electron-giving groups such as -N(CH
)
and -OCH
decrease the strength of the bond. For the same substituent, the one at the Y site has a higher effect on hydrogen bonding than that at the X site. By NBO analysis, it was found that the substituents would cause charge redistribution of the individual atoms of 2,4-dihydroxybenzophenones, thus affecting the formation and strength of the hydrogen bonds. Moreover, when the substituent is at the Y substitution site, the oxygen atom of the carbonyl group is less able to absorb electrons and more charge is attracted to the oxygen atom of the hydroxyl group, resulting in a larger charge difference between the two oxygen atoms and an increase of bond energy. Finally, a multiple linear regression analysis of the NPA charge number of the atoms involved in the formation of the hydrogen-bonded chelated six-membered ring was performed with the energy of the hydrogen bond and the percentage of influencing factors estimated, which were found to jointly affect the strength of hydrogen bonding. The aim of this study is to provide theoretical guidance for the design of benzophenone-based UV absorbers that absorb UV light of specific wavelength bands.
High specific energy microsupercapacitor (MSC) as miniature all solid-state energy storage device has attracted wide interest due to its high energy and power density, long cycle life, integrability ...and high safety. Here, we designed and fabricated symmetric microsupercapacitors by one-step laser direct writing of boron-doped electrolytes (B-LE). The boron-doped PVA/H2SO4 electrolyte was carbonized into interdigitated cross-linked porous carbon fiber electrodes by high energy laser irradiation. These devices can deliver a high areal capacitance of 1.57 mF cm−2 (corresponding volumetric capacitance of 3.14 F cm−3) at the current density of 0.01 mA cm−2 with 5 wt% H3BO3 loading, much higher than the devices without boron doping (0.40 mF cm−2 at the same current density). Moreover, the fabricated devices display good cycling stability with a capacitance retention of 89.27% after 3000 charge-discharge cycles. These results suggest that the one-step direct laser writing to fabricate symmetric MSC has broad applications in high energy and power storage devices for miniaturized electronics.
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Despite the mitochondrial antiviral signalling protein (MAVS)-dependent RIG-I-like receptor (RLR) signalling pathway in the cytosol plays an indispensable role in the antiviral immunity of the host, ...surprising little is known in invertebrates. Here we characterized the major members of RLR pathway and investigated their signal transduction a Molluscs. We show that genes involved in RLR pathway were significantly induced during virus challenge, including CgRIG-I-1, CgMAVS, CgTRAF6 (TNF receptor-associated factor 6), and CgIRFs (interferon regulatory factors. Similar to human RIG-I, oyster RIG-I-1 could bind poly(I:C) directly in vitro and interact with oyster MAVS via its caspase activation and recruitment domains. We also show that transmembrane domain-dependent self-association of CgMAVS may be crucial for its signalling and that CgMAVS can recruit the downstream signalling molecule, TRAF6, which can subsequently activate NF-κB signal pathway. Moreover, oyster IRFs appeared to function downstream of CgMAVS and were able to activate the interferon β promoter and interferon stimulated response elements in mammalian cells. These results establish invertebrate MAVS-dependent RLR signalling for the first time and would be helpful for deciphering the antiviral mechanisms of invertebrates and understanding the development of the vertebrate RLR network.
Gold nanoparticles decorated WS2 microflakes (Au/WS2) have been synthesized by an in situ chemical reducing process. A chemiresistive-type sensor using as-synthesized Au/WS2 heterostructures as ...sensing materials shows an improved response to different concentrations of ammonia compared to pure WS2 at room temperature. As the concentrations of gold nanoparticles increased in heterostructures, response/recovery speeds of the sensors became faster although the sensitivity of the sensor was compromised compared to the sensitivity of the sensor with lower concentrations of Au. In addition, the Au/WS2-based sensor indicated excellent selectivity to formaldehyde, ethanol, benzene and acetone at room temperature. The improved performance of the sensors was attributed to the synergistic effect of electronic sensitization and chemical sensitization between WS2 and Au.
Hatchery-reared larvae of the Pacific oyster (Crassostrea gigas) often suffer from massive mortality induced by Ostreid herpesvirus 1 (OsHV-1) infection, indicating the importance of better ...understanding of oyster immune defense systems. The accuracy of measurements of gene expression levels based on quantitative real-time PCR assays relies on the use of housekeeping genes as internal controls; however, few studies have focused on the selection of such internal controls. In this study, we conducted a comprehensive investigation of internal control genes during oyster development in virus-infected and uninfected samples. Transcriptome data for 38 developmental stages were downloaded and the gene expression patterns were classified into 30 clusters. A total of 317 orthologs of classical housekeeping genes in the oyster genome were annotated. After combining the expression profiles and oyster housekeeping gene dataset, 14 candidate internal controls were selected for further investigation: Elongation factor-1α (EF-1α), 18S rRNA (18S), 28S rRNA (28S), Glyceraldehyde 3-phosphate dehydrogenase (GAPDH), β-actin (ACT), Ribosomal protein L7 (RL7), Ribosomal protein L27 (RL27), Ribosomal protein L36 (RL36), Ribosomal protein S18 (RS18), Heterogeneous nuclear ribonucleoprotein A2/B1 (RO21), Eukaryotic translation elongation factor 2 (EF2), Ubiquitin-conjugating enzyme E2D2 (UBCD1), S-phase kinase-associated protein 1 (SKP1) and Heterogeneous nuclear ribonucleoprotein Q (HNRPQ). RNA was extracted from oyster larvae infected with OsHV-1 (group A; GA), and OsHV-1 free larvae (group B; GB). The expression levels of the 14 candidate internal controls were studied in GA and GB larvae by real-time PCR. Their expression stabilities were further analyzed using the GeNorm program. RL7 and RS18 were the most stable genes in both OsHV-1 infected (GA) and uninfected (GB) larvae. These results suggest that RL7 and RS18 could be used as internal controls for studying gene expression in normal growing oyster larvae and in OsHV-1 infected larvae. These high quality internal controls will be a valuable resource in future studies of oyster larval mortality.
► Describing the evaluation of C. gigas housekeeping genes in developmental stages. ► RL7 and RS18 are the most suitable internal controls for qRT-PCR in C. gigas larvae. ► EF-1α, 18S, 28S, GAPDH and ACT are not suitable internal controls in C. gigas larvae.
Aiming at the problem that the optimal demodulation band is difficult for accurately selecting in the fault diagnosis of rolling bearings, Weighted Time–Frequency Energy Ratio (WTFER) which performs ...a weighted fusion of Impulse Norm and Envelope Spectrum Energy Ratio is utilized as the indicator for determining the optimal demodulation band. Since WTFER takes into account the impulsiveness and sparsity of the fault signal in the time domain and envelope spectrum domain, respectively, it has strong robustness to noise. What’s more, Maximum Overlap Discrete Wavelet Packet Transform (MODWPT) is applied for filtering considering its feature of maintaining full resolution. Combining MODWPT and WTFER, we propose a new algorithm named Wtfergram since its concept is homologous to Kurtogram. Simulation and engineering signal are analyzed to verify the superiority of Wtfergram.
Caspase-3 and caspase-7 are two key effector caspases that play important roles in apoptotic pathways that maintain normal tissue and organ development and homeostasis. However, little is known about ...the sequence, structure, activity, and function of effector caspases upon apoptosis in mollusks, especially marine bivalves. In this study, we investigated the possible roles of two executioner caspases in the regulation of apoptosis in the Pacific oyster Crassostrea gigas. A full-length caspase-3-like gene named Cgcaspase-3 was cloned from C.gigas cDNA, encoding a predicted protein containing caspase family p20 and p10 domain profiles and a conserved caspase active site motif. Phylogenetic analysis demonstrated that both Cgcaspase-3 and Cgcaspase-1 may function as effector caspases clustered in the invertebrate branch. Although the sequence identities between the two caspases was low, both enzymes possessed executioner caspase activity and were capable of inducing cell death. These results suggested that Cgcaspase-3 and Cgcaspase-1 were two effector caspases in C. gigas. We also observed that nucleus-localized Cgcaspase-3, may function as a caspase-3-like protein and cytoplasm-localized Cgcaspase-1 may function as a caspase-7-like protein. Both Cgcaspase-3 and Cgcaspase-1 mRNA expression increased after larvae settled on the substratum, suggesting that both caspases acted in several tissues or organs that degenerated after oyster larvae settlement. The highest caspase expression levels were observed in the gills indicating that both effector caspases were likely involved in immune or metabolic processes in C. gigas.
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