Effects of chronic cold stress on tissue structure, antioxidant response, and key gene expression in the warm-water bivalve Chlamys nobilis.

As ectothermic invertebrates, mollusks are regarded as good environmental indicator species for determining the adverse effects of climate change on marine organisms. In the present study, the effects of cold stress on the tissue structure, antioxidant activity, and expression levels of genes were evaluated in the warm-water noble scallop Chlamys nobilis by simulating natural seawater cooled down during winter from 17 °C to 14 °C, 12 °C, 10 °C, and 9 °C. Firstly, the gill was severely damaged at 10 °C and 9 °C, indicating that it could be used as a visually indicative organ for monitoring cold stress. The methylenedioxyamphetamine (MDA) content significantly increased with the temperatures decreasing, meanwhile, the antioxidant enzyme activities superoxide dismutase (SOD) and catalase (CAT) showed a similar pattern, suggesting that the scallop made a positive response. More importantly, 6179 genes related to low temperatures were constructed in a module-gene clustering heat map including 10 modules. Furthermore, three gene modules about membrane lipid metabolism, amino acid metabolism, and molecular defense were identified. Finally, six key genes were verified, and HEATR1, HSP70B2, PI3K, and ATP6V1B were significantly upregulated, while WNT6 and SHMT were significantly downregulated under cold stress. This study provides a dynamic demonstration of the major gene pathways' response to various low-temperature stresses from a transcriptomic perspective. The findings shed light on how warm-water bivalves can tolerate cold stress and can help in breeding new strains of aquatic organisms with low-temperature resistance.

Optimizing multi-user indoor sound communications with acoustic reconfigurable metasurfaces.

Sound in indoor spaces forms a complex wavefield due to multiple scattering encountered by the sound. Indoor acoustic communication involving multiple sources and receivers thus inevitably suffers from cross-talks. Here, we demonstrate the isolation of acoustic communication channels in a room by wavefield shaping using acoustic reconfigurable metasurfaces (ARMs) controlled by optimization protocols based on communication theories. The ARMs have 200 electrically switchable units, each selectively offering 0 or π phase shifts in the reflected waves. The sound field is reshaped for maximal Shannon capacity and minimal cross-talk simultaneously. We demonstrate diverse acoustic functionalities over a spectrum much larger than the coherence bandwidth of the room, including multi-channel, multi-spectral channel isolations, and frequency-multiplexed acoustic communication. Our work shows that wavefield shaping in complex media can offer new strategies for future acoustic engineering.

High-toughness, extensile and self-healing PDMS elastomers constructed by decuple hydrogen bonding.

Elastomers are widely used in traditional industries and new intelligent fields. However, they are inevitably damaged by electricity, heat, force, etc. during the working process. With the continuous improvement of reliability and environmental protection requirements in human production and living, it is vital to develop elastomer materials with good mechanical properties that are not easily damaged and can self-heal after being damaged. Nevertheless, there are often contradictions between mechanical properties and self-healing as well as toughness, strength, and ductility. Herein, a strong and dynamic decuple hydrogen bonding based on carbon hydrazide (CHZ) is reported, accompanied with soft polydimethylsiloxane (PDMS) chains to prepare self-healing (efficiency 98.7%), recyclable, and robust elastomers (CHZ-PDMS). The strategy of decuple hydrogen bonding will significantly impact the study of the mechanical properties of elastomers. High stretchability (1731%) and a high toughness of 23.31 MJ m-3 are achieved due to the phase-separated structure and energy dissipation. The recyclability of CHZ-PDMS further supports the concept of environmental protection. The application of CHZ-PDMS as a flexible strain sensor exhibited high sensitivity.

Genome-wide identification of STATs and analysis of their role in sex determination in Pacific oysters (Crassostrea gigas).

STAT (signal transducer and activator of the transcription) proteins, are a group of highly conserved transcription factors and fundamental components of the JAK-STAT signaling pathway. They play crucial roles in a variety of biological processes, such as immunity, proliferation, differentiation, and growth. However, little information is known regarding their role in gonad development and sex determination in mollusks. In this study, we identified 3 STAT genes in Pacific Oyster Crassostrea gigas. Phylogenetic analysis showed that STATs from mollusks were highly conserved, and most of them had four identical motif regions, except for the STAT1 and STAT3 predicted sequences from Crassostrea hongkongensis. Tissue expression analysis indicated CgSTAT1 had a high expression level in most tissues, while CgSTAT3 had a low expression level in most tissues. Expression analysis of early developmental stages showed CgSTAT1 had a higher expression level from egg to D shaped larva and a lower expression level in subsequent stages. In contrast CgSTAT1, CgSTAT2 had a reverse expression pattern. Expression analysis of different developmental stages of diploid gonads indicated that CgSTAT1 had a higher expression level at the S1 and S3 stages relative to the S2 stage in females, while in males the S3 stage had a higher expression than than the S2 stage. The expression level of CgSTAT1 between diploids and triploids in females differed significantly, but there were no significant differences in males. Expression of CgSTAT2 differed significantly between diploid and triploid males. These data suggest an important role for STATs in sex differentiation in diploid and triploid oysters. Our study is the first to explore the role of STATs in sex differentiation and gonadal development in oysters, and will help us better understand the molecular mechanisms of sex differentiation in shellfish.

Effects of high stocking density on growth performance and expression of MyD88, and its temporal expression under the challenge of Vibrio parahaemolyticus in the noble scallop Chlamys nobilis.

High stocking density has been regarded as an adverse factor in bivalve aquaculture. However, its subsequent molecular response to pathogenic bacteria has been little studied. In order to study the question, a novel MyD88 was first cloned using adult noble scallops Chlamys nobilis (CnMyD88), and its tissue distribution was investigated. Then, 1860 juvenile scallops were divided into two groups with two initial densities of high density (200 individuals/layer, HD) and normal density (110 individuals/layer, ND) and in-situ cultured for three months, in which their growth, survival, and the differential expression of CnMyD88 were examined, respectively. Finally, scallops were injected with the Vibrio parahaemolyticus to assess the temporal expression of CnMyD88. As the results show, CnMyD88 cDNA has a full length of 2241 bp and contains an 1107 bp ORF that encodes a 368-derived protein. It was widely expressed in examined tissues with a significantly higher level in hemolymph, intestine, mantle, and gonad than others. Besides, the HD group showed lower growth (0.39 ± 0.05 mm/day) and survival (37.00 ± 8.49%) than the ND group (0.55 ± 0.02 mm/day and 76.82 ± 5.78%). More importantly, the HD group exhibited significantly lower expression levels of CnMyD88 in their examined tissues than the ND group. After V. parahaemolyticus challenging, CnMyD88 had significantly lower expression levels in the scallops from the HD group than that of the scallops from the ND group at 6th, 24th, and 36th. The present results indicated that high stocking density not only made adverse impacts on growth and survival but also may induce immunosuppression in the noble scallop. Therefore, appropriate low stocking density may be worth considering to adopt in scallop aquaculture.

Dynamic Sustainable Polyimide Film Combining Hardness with Softness via a "Mimosa-Like" Bionic Strategy.

Dielectric polyimides (PIs) are ubiquitous as insulation in electrical power systems and electronic devices. Generally, dynamic polyimide is required to solve irreversible failure processes of electrical or mechanical damage, for example, under high temperature, pressure, and field strength. The challenge lies in the design of the molecular structure of rigid polyimide to achieve dynamic reversibility. Herein, a low-molecular-weight polyimide gene unit is designed to crosslink with polyimide ligase to prepare the smart film. Interestingly, due to the variability of gene unit and ligase combinations, the polyimide films combining hardness with softness are designed into three forms via a "Mimosa-like" bionic strategy to adapt to different application scenarios. Meanwhile, the films have good degradation efficiency, excellent recyclability, and can be self-healable, which makes them reuse. Clearly, the films can be used in the preparation of ultrafast sensors with a response time ≈0.15 s and the application of corona-resistant films with 100% recovery. Furthermore, the construction of polyimide and carbon-fiber-reinforced composites (CFRCs) has been verified to apply to the worse environment. Nicely, the composites have the property of multiple cycles and the non-destructive recycle rate of carbon fiber (CF) is as high as 100%. The design idea of preparing high-strength dynamic polyimide by crosslinking simple polyimide gene unit with ligase could provide a good foundation and a clear case for the sustainable development of electrical and electronic polyimides, from the perspective of Mimosa bionics.

Carotenoid content and composition: A special focus on commercially important fish and shellfish.

Carotenoids are natural pigments that provide many health benefits to living organisms. Although terrestrial plants are the major dietary source of carotenoids for humans, aquatic animals (especially fish and shellfish) are equally important because they are rich in certain important carotenoids lacking in fruits and vegetables. Although extensive research has focused on exploring the carotenoid content and composition in fish and shellfish, this information is poorly organized. This paper reviews the scientific evidence for the carotenoid content and composition in fish and shellfish. It makes serious attempts to summarize the relevant data published on specific research questions in order to improve the understanding of various evidence to clarify the research status of carotenoids in fish and shellfish and defining topics for future studies. From the analysis of published data, it is obvious that most fish and shellfish are rich in complex carotenoids (e.g. astaxanthin, fucoxanthin, fucoxanthinol, lutein). These carotenoids have stronger antioxidant effect, higher efficiency in removing the singlet oxygen and the peroxyl radicals, and have a variety of health benefits. Carotenoid levels in fish and shellfish depend on genotype, climatic conditions of the production area, storage and cooking methods. However, the information of the bioavailability of fish/shellfish carotenoids to human is very limited, which hinders the actual contributions to health. The findings of this study can be used as a guide to select appropriate fish and shellfish as dietary sources of carotenoids, and provide information about potential fish and shellfish species for aquaculture to produce carotenoids to meet part of the growing demand for natural carotenoids.

Annotation Guidelines for Medication Errors in Incident Reports: Validation Through a Mixed Methods Approach.

At present no adequate annotation guidelines exists for incident report learning. This study aims at utilizing multiple quantitative and qualitative evidence to validate annotation guidelines for incident reporting of medication errors. Through multiple approaches via annotator training, annotation performance evaluation, exit surveys, and user and expert interviews, a mixed methods explanatory sequential design was utilized to collect 2-stage evidence for validation. We recruited two patient safety experts to participate in piloting, three annotators to receive annotation training and provide user feedback, and two incident report system designers to offer expert comments. Regarding the annotation performance evaluation, the overall accuracy reached 97% and 90% for named entity identification and attribute identification respectively. Participants provided invaluable comments and opinions towards improving the annotation methods. The mixed methods approach created a significant evidential basis for the use of annotation guidelines for incident report of medication errors. Further expansion of the guidelines and external validity present options for future research.

Identification of a key gene StAR-like-3 responsible for carotenoids accumulation in the noble scallop Chlamys nobilis.

Carotenoids play important roles in living organisms. However, animals cannot synthesize carotenoids by themselves, and they must absorb and accumulate carotenoids from their diets in which some key genes are involved. In present study, a gene named StAR-like-3 was characterized in the noble scallop Chlamys nobilis, and its function was identified using golden scallops with higher carotenoids content and brown scallops with less carotenoids content by immunohistochemistry, carotenoid binding assay and RNAi. Results showed that the StAR-like-3 encodes a 54.7 kDa transmembrane protein (named as StAR3) of 481 amino acids containing a MENTAL domain and a START (Steroidogenic acute regulatory protein-related lipid transfer) domain, and its expression level in hemocytes and intestine of golden scallops were significantly higher than those of brown ones. Subsequently, the StAR3 protein was detected in the intestinal epithelial cells of golden scallops, and recombinant StAR3 could bind lutein conjugated to protein G and antibody to form a yellow complex, suggesting it is a carotenoid binding protein involving in carotenoids accumulation in golden scallops. Furthermore, total carotenoids content of hemolymph in golden scallops was significantly decreased when the expression of StAR-like-3 suppressed, suggesting this gene plays an important role in transport of carotenoids. Conclusion, the present results indicated that the StAR-like-3 is a key gene responsible for the carotenoids accumulation in the scallop.

Intraspecific hybridization as a mitigation strategy of ocean acidification in marine bivalve noble scallop Chlamys nobilis.

The driving factors of climate change, especially ocean acidification (OA), have many detrimental impacts on marine bivalves. Hybridization is one of the important methods to improve environmental tolerance of animals and plants. In this study, we explored the feasibility of intraspecific hybridization as an OA mitigation strategy in noble scallop Chlamys nobilis (ecologically and economically important bivalve species). The results of this study revealed that exposure of C. nobilis to OA condition significantly reduced the hatching rate, survival rate, growth rate (shell height, shell length, shell width and shell weight), and total carotenoid content (TCC), as well as increased the deformity rate of C. nobilis larvae. Interestingly, under both ambient water and OA condition, the intraspecific hybridization of C. nobilis exhibited heterosis in terms of hatching rate, survival rate and growth rate (excepted for growth in shell length under OA). Transcriptome sequencing of C. nobilis (inbreed and hybrid under ambient and OA conditions) identified four main differentially expressed genes involved in signal transduction, biological process maintenances, nucleic acid binding and post-translational modification. In addition, the expression of these four genes in hybrid C. nobilis was significantly higher than that in inbreed C. nobilis. In conclusion, hybrid C. nobilis showed heterosis in growth rate and survival rate under both ambient water and acidified seawater condition, which may be the result of enhanced expression of genes related to signal transduction, DNA replication and post-translational modification.

Climate change and n-3 LC-PUFA availability.

Omega-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA) are essential fatty acids for the growth, development and survival of virtually all organisms. There is increasing evidence that anthropogenic climate change has a direct and indirect impact on the availability of natural n-3 LC-PUFA. However, this information is fragmented and not well organized. Therefore, this article reviewed published data from laboratory experiments, field experiments and model simulations to reveal the impact of climate change on the global supply of natural n-3 LC-PUFA and how this will limit the availability of n-3 LC-PUFA in the future food web. In general, climate change can significantly reduce the availability of natural n-3 LC-PUFA in grazing food webs in the following ways: 1) decrease the total biomass of phytoplankton and shift the plankton community structure to a smaller size, which also reduce the biomass of animals in higher trophics; 2) reduce the n-3 LC-PUFA content and/or quality (n-3: n-6 ratio) of all marine organisms; 3) reduce the transfer efficiency of n-3 LC-PUFA in grazing food web. In addition, as an anthropogenic climate adaptation measure, this review also proposed some alternative sources of n-3 LC-PUFA and determined the direction of future research. The information in this article is very useful for providing a critical analysis of the impact of climate change on the supply of natural n-3 LC-PUFA. Such information will aid to establish climate adaptation or management measures, and determine the direction of future research.

Lipid nutritional quality of marine and freshwater bivalves and their aquaculture potential.

Omega-3 Long-chain polyunsaturated fatty acids (n-3 LC-PUFA) are beneficial to human health. Since the industrial revolution, with the tremendous increase of human population, the supply of natural n-3 LC-PUFA is far lower than the nutritional need of n-3 LC-PUFA. Therefore, a new alternative source of natural n-3 LC-PUFA is urgently needed to reduce the supply and demand gap of n-3 LC-PUFA. Mollusks, mainly bivalves, are rich in n-3 LC-PUFA, but the information of bivalves' lipid profile is not well organized. Therefore, this study aims to analyze the published fatty acid profiles of bivalves and reveal the potential of bivalve aquaculture in meeting the nutritional needs of human for n-3 LC-PUFA. There are growing evidence show that the nutritional quality of bivalve lipid is not only species-specific, but also geographical specific. To date, bivalve aquaculture has not been evenly practiced across the globe. It can be seen that aquaculture is predominant in Asia, especially China. Unlike fish aquaculture, bivalve aquaculture does not rely on fishmeal and fish oil inputs, so it has better room for expansion. In order to unleash the full potential of bivalve aquaculture, there are some challenges need to be addressed, including recurrent mass mortalities of farmed bivalves, food safety and food security issues. The information of this article is very useful to provide an overview of lipid nutritional quality of bivalves, and reveal the potential of bivalve aquaculture in meeting the growing demand of human for n-3 LC-PUFA.

Creating synthetic spaces for higher-order topological sound transport.

Modern technological advances allow for the study of systems with additional synthetic dimensions. Higher-order topological insulators in topological states of matters have been pursued in lower physical dimensions by exploiting synthetic dimensions with phase transitions. While synthetic dimensions can be rendered in the photonics and cold atomic gases, little to no work has been succeeded in acoustics because acoustic wave-guides cannot be weakly coupled in a continuous fashion. Here, we formulate the theoretical principles and manufacture acoustic crystals composed of arrays of acoustic cavities strongly coupled through modulated channels to evidence one-dimensional (1D) and two-dimensional (2D) dynamic topological pumpings. In particular, the higher-order topological edge-bulk-edge and corner-bulk-corner transport are physically illustrated in finite-sized acoustic structures. We delineate the generated 2D and four-dimensional (4D) quantum Hall effects by calculating first and second Chern numbers and physically demonstrate robustness against the geometrical imperfections. Synthetic dimensions could provide a powerful way for acoustic topological wave steering and open up a platform to explore any continuous orbit in higher-order topological matter in dimensions four and higher.

Potential causative factors of noble scallop Chlamys nobilis mass mortality in Nan'ao Island, Shantou, China in 2017.

Noble scallop Chlamys nobilis is an important marine bivalve that has been extensively cultured in the south coast of China since the 1980s. Unfortunately, since the late 1990s, the farmed scallops often suffered from regional mass mortality, which results in enormous economic losses to farmers and industries. In 2017, another mass mortality event occurred in Nan'ao Island, Shantou, China. In this study, the cause of C. nobilis mass mortality in 2017 was first investigated in the field, and then validated in a laboratory experiment. In the field, three sampling sites were selected according to the scallop mortality rate: Hunter Bay (90% mortality), Baisha Bay (67% mortality) and Longhai (6% mortality). Meanwhile, environmental parameters (temperature, salinity, DO, pH and chlorophyll a) of each site were also measured in situ. Then, water and scallop samples were collected randomly for the analysis of phytoplankton diversity and algal toxin activity using 18S rDNA and PP2A inhibition assay, respectively. In laboratory, healthy scallops were challenged with Karenia mikimotoi (1 × 103 cells/mL) for 30 h. The field results showed that no significant difference in those environmental parameters existed among the three sites, but the relative abundance of K. mikimotoi in seawater and scallops' intestines in Hunter Bay and Baisha Bay was significantly higher than that in Longhai, and sick scallops contained significantly higher algal toxin activity than healthy ones. Laboratory results revealed that challenged scallops with K. mikimotoi showed significantly higher mortality rate and algal toxin activity than healthy ones, and low density of K. mikimotoi (1 × 103 cells/mL) was sufficient to cause >50% scallops' mortality within 26 h. This study provides the first evidence that low K. mikimotoi cell density can cause massive mortality in C. nobilis, and provides useful information as guide to prevent scallop mass mortality in the future.

Creation of acoustic vortex knots.

Knots and links have been conjectured to play a fundamental role in a wide range of scientific fields. Recently, tying isolated vortex knots in the complex optical field has been realized. However, how to construct the acoustic vortex knot is still an unknown problem. Here we propose theoretically and demonstrate experimentally the creation of acoustic vortex knots using metamaterials, with decoupled modulation of transmitted phase and amplitude. Based on the numerical simulation, we find that the knot function can be embedded into the acoustic field by designed metamaterials with only 24 × 24 pixels. Furthermore, using the optimized metamaterials, the acoustic fields with Hopf link and trefoil knot vortex lines have been observed experimentally.

Differential responses of a pi-class glutathione S-transferase (CnGSTp) expression and antioxidant status between golden and brown noble scallops under pathogenic stress.

Glutathione S-transferases (GSTs) play important roles in immunity by protecting organisms against the damage of reactive oxygen species (ROS). In this study, a pi-class GST cDNA sequence was first cloned from noble scallop Chlamys nobilis (named CnGSTp). The full length cDNA of CnGSTp was 922 bp, encoding a cytosolic protein of 202 amino acids residues, with predicted molecular masses of 23.1 kDa. Then an acute Vibrio Parahaemolyticus challenge experiment was conducted by using the Golden and Brown noble scallops with different total carotenoids content (TCC), and CnGSTp expression level, TCC and ROS level was separately determined. The results showed that ROS and CnGSTp expression levels were significantly up-regulate under Vibrio Parahaemolyticus challenge than the control group (P < 0.05). The Golden scallops showed significantly higher CnGSTp expression level and lower ROS level in hemocytes than the Brown ones (P < 0.05). Moreover, there is a significantly positive correlation between TCC and ROS in the Golden scallops. The present results revealed that CnGSTp plays important roles in immune response and carotenoids play assistant roles in antioxidant defense system under pathogenic stress in the noble scallop.

Effects of high stocking density on the galectin gene expression in noble scallop Chalmys nobilis under bacterial infection.

High stocking densities have been shown to have adverse effects on the physiology of bivalves. The noble scallop Chlamys nobilis is one of the most important cultured shellfish in Southern China. However, the effects of scallop stocking density on its immunity is not well understood. In this context, this study was conducted to assess the effect of high stocking density on the galectin (an important protein in innate immunity) gene expression of C. nobilis during bacterial infection. A full-length galectin (CnGal) gene was cloned. The ORF of the CnGal cDNA encodes a predicted protein containing 549 aa with four CRDs and no signal peptide. Our results reveal that high stocking density in the scallop not only led to high mortality and slow growth, but also changed tissue distribution of the CnGal expression. The individuals from the high stocking density group exhibited more differences among tissues than those from the control group, but the highest expression were both recorded in hemolymph. After the Vibrio parahaeomlyticus challenge, the gene's expression levels were all significantly up-regulated in the hemolymph and gill, but the time up to peak was different between the two tissues. The findings of this study could fill a gap in knowledge about how high stocking density affect scallop immunity at the molecular level.

Identification and molecular characterization of peroxiredoxin 6 from noble scallop Chlamys nobilis revealing its potent immune response and antioxidant property.

The 1-cyseine peroxiredoxin (Prx6) is an importantly antioxidant enzyme that protects cells from oxidative damage caused by excessive production of reactive oxygen species (ROS). In this study, we described the molecular characteristics of the noble scallop Chlamys nobilis peroxiredoxin 6 (designed as CnPrx6), immune responses and DNA protection activity of the recombinant protein. The complete ORF (696 bp) of CnPrx6 encoded a polypeptide (25.5 kDa) of 231 amino acids, harboring a conserved peroxidase catalytic center (41PVCTTE46) and the catalytic triads putatively involved in peroxidase and phospholipase A2 activities. The deduced amino acid sequence of CnPrx6 shared a relatively high amino acid sequence similarity (more than 50%). The qRT-PCR revealed that the CnPrx6 mRNA was constitutively expressed in all examined tissues, with the highest expression observed in adductor. Upon immunological challenge with Vibrio parahaemolyticus, lipopolysaccharides (LPS) and polyinosinic-polycytidylic acid (Poly I:C), the expression level of CnPrx6 mRNA was significantly up-regulated (P < 0.05). Furthermore, there was a significant difference (P < 0.05) in the expression level of CnPrx6 between golden and brown scallops. The purified recombinant CnPrx6 protein protected the supercoiled plasmid DNA from metal-catalyzed ROS damage. Taken together, these results indicated that the CnPrx6 may play an important role in modulating immune responses and minimizing DNA damage in noble scallop Chlamys nobilis.

A novel carotenoids-producing marine bacterium from noble scallop Chlamys nobilis and antioxidant activities of its carotenoid compositions.

Marine bacteria produce many bioactive compounds, including carotenoids. However, the quality of bacterium carotenoids is relatively unknown. Therefore, in this study, a novel carotenoids-producing bacterium Brevundimonas scallop Zheng & Liu was isolated from Chlamys nobilis. The genome of the isolate was analyzed, carotenoid compounds were screened using HPLC-MS and the carotenoid production in B. scallop was monitored. The results revealed that the genome of B. scallop contained a carotenoid synthesis gene cluster, which involved in astaxanthin and hydroxy-astaxanthin biosynthesis. The 2,2'-dihydroxy-astaxanthin was the major carotenoid produced by B. scallop. The optimum culture condition for the highest carotenoids production (1303.62 ± 61.06 µg/g dry cells) for B. scallop was at temperature and salinity of 20 °C and 3% salt, respectively, in 10 g/L glucose as carbon source. The results showed the B. scallop is a new carotenoids resource in marine bivalve, which has an excellent antioxidative activity and potential industrial use.

Comparison of Gut Microbiota Between Golden and Brown Noble Scallop Chlamys nobilis and Its Association With Carotenoids.

Many marine bivalves are regarded as healthy foods due to their high carotenoid content. Only plants and microorganisms have natural carotenoids biosynthesis ability, hence, animals such as bivalves must obtain carotenoids from their diets. Due to the filter-feeding behavior of bivalves, they have high diversity of gut microbes. However, the relationship between gut microbes and carotenoids has not been explored in mollusks. In the present study, the interaction between gut microbes and carotenoids in two polymorphic noble scallop Chlamys nobilis, golden scallops (designated GG) and brown scallops (designated BW), were studied. The gut of GG and BW showed statistically different bacteria communities. Results from 16S rRNA gene sequencing and qPCR analysis revealed that the gut of GG had significantly higher relative abundance of carotenoids-producing bacteria Brevundimonas, compared with BW. Moreover, HPLC-MS analysis showed that isolate Brevundimonas could produce astaxanthin. The current findings are very useful as they could form the basis for future studies in determining the relationship between gut microbiota and carotenoids absorption in bivalves.