ABSTRACT
The bay scallop is a eurythermal species with high economic value and now represents the most cultured bivalve species in China. Two subspecies of the bay scallop, the northern subspecies Argopecten irradians irradians Korean population (KK) and the southern subspecies Argopecten irradians concentricus (MM), exhibited distinct adaptations to heat stress. However, the molecular mechanism of heat resistance of the two subspecies remains unclear. In this study, we compared the transcriptomic responses of the two subspecies to heat stress and identified the involved differentially expressed genes (DEGs) and pathways. More DEGs were found in the KK than in the MM when exposed to high temperatures, indicating elevated sensitivity to thermal stress in the KK. Enrichment analysis suggests that KK scallops may respond to heat stress more swiftly by regulating GTPase activity. Meanwhile, MM scallops exhibited higher resistance to heat stress mainly by effective activation of their antioxidant system. Chaperone proteins may play different roles in responses to heat stress in the two subspecies. In both subspecies, the expression levels of antioxidants such as GST were significantly increased; the glycolysis process regulated by PC and PCK1 was greatly intensified; and both apoptotic and anti-apoptotic systems were significantly activated. The pathways related to protein translation and hydrolysis, oxidoreductase activity, organic acid metabolism, and cell apoptosis may also play pivotal roles in the responses to heat stress. The results of this study may provide a theoretical basis for marker-assisted breeding of heat-resistant strains.
Subject(s)
Gene Expression Profiling , Pectinidae , Transcriptome , Animals , Pectinidae/genetics , Pectinidae/physiology , Thermotolerance/genetics , Heat-Shock ResponseABSTRACT
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.
Subject(s)
Antioxidants , Cold-Shock Response , Pectinidae , Animals , Pectinidae/genetics , Pectinidae/physiology , Pectinidae/metabolism , Antioxidants/metabolism , Gills/metabolism , Gene Expression Regulation , Transcriptome , Superoxide Dismutase/genetics , Superoxide Dismutase/metabolismABSTRACT
High temperature increases energy demand in ectotherms, limiting their physiological capability to cope with hypoxic events. The present study aimed to assess the metabolic tolerance of juvenile Nodipecten subnodosus scallops to acute hyperthermia combined with moderate hypoxia. A previous study showed that juveniles exhibited a high upper temperature limit (32 °C), but the responses of juveniles to combined hyperthermia and low dissolved oxygen are unknown. Scallops were exposed to control conditions (treatment C: 22 °C, â¼7.1 mg O2 L-1 or PO2 156.9 mmHg), acute hyperthermia under normoxia (treatment T: 30 °C, â¼6.0 mg O2 L-1 or PO2 150.9 mmHg) or acute hyperthermia plus hypoxia (treatment TH: 30 °C, â¼2.5 mg O2 L-1 or PO2 62.5 mmHg) for 18 h. In T, juveniles exhibited an enhanced oxygen consumption, together with a decrease in adenylate energy charge (AEC) and arginine phosphate (ArgP), and with no changes in metabolic enzyme activity in the muscle. In TH, scallops maintained similar AEC and ArgP levels in muscle as those observed in T treatment. This response occurred along with the accumulation of inosine monophosphate and hypoxanthine. Besides, reduced citrate synthase and pyruvate kinase activities, enhanced hexokinase activity, and a higher octopine dehydrogenase/lactate dehydrogenase ratio in the mantle indicated the onset of anaerobiosis in TH. These responses indicate that juvenile scallops showed tissue-specific compensatory responses regarding their energy balance under moderate hypoxia at high temperatures. Our results give an insight into the tolerance limit of this species to combined hyperthermia and hypoxia in its northern limit of distribution.
Subject(s)
Oxygen , Pectinidae , Animals , Temperature , Energy Metabolism , Hypoxia/metabolism , Pectinidae/physiology , Adenosine Monophosphate/metabolism , Oxygen ConsumptionABSTRACT
The presence of supercooled water in polar regions causes anchor ice to grow on submerged objects, generating costly problems for engineered materials and life-endangering risks for benthic communities. The factors driving underwater ice accretion are poorly understood, and passive prevention mechanisms remain unknown. Here we report that the Antarctic scallop Adamussium colbecki appears to remain ice-free in shallow Antarctic marine environments where underwater ice growth is prevalent. In contrast, scallops colonized by bush sponges in the same microhabitat grow ice and are removed from the population. Characterization of the Antarctic scallop shells revealed a hierarchical micro-ridge structure with sub-micron nano-ridges which promotes directed icing. This concentrates the formation of ice on the growth rings while leaving the regions in between free of ice, and appears to reduce ice-to-shell adhesion when compared to temperate species that do not possess highly ordered surface structures. The ability to control the formation of ice may enable passive underwater anti-icing protection, with the removal of ice possibly facilitated by ocean currents or scallop movements. We term this behavior cryofouling avoidance. We posit that the evolution of natural anti-icing structures is a key trait for the survival of Antarctic scallops in anchor ice zones.
Subject(s)
Freezing , Ice , Pectinidae/physiology , Adaptation, Physiological , Animals , Antarctic Regions , EcosystemABSTRACT
We have a growing understanding of the light-sensing organs and light-influenced behaviours of animals with distributed visual systems, but we have yet to learn how these animals convert visual input into behavioural output. It has been suggested they consolidate visual information early in their sensory-motor pathways, resulting in them being able to detect visual cues (spatial resolution) without being able to locate them (spatial vision). To explore how an animal with dozens of eyes processes visual information, we analysed the responses of the bay scallop Argopecten irradians to both static and rotating visual stimuli. We found A. irradians distinguish between static visual stimuli in different locations by directing their sensory tentacles towards them and were more likely to point their extended tentacles towards larger visual stimuli. We also found that scallops track rotating stimuli with individual tentacles and with rotating waves of tentacle extension. Our results show, to our knowledge for the first time that scallops have both spatial resolution and spatial vision, indicating their sensory-motor circuits include neural representations of their visual surroundings. Exploring a wide range of animals with distributed visual systems will help us learn the different ways non-cephalized animals convert sensory input into behavioural output.
Subject(s)
Pectinidae , Animals , Pectinidae/physiology , Vision, OcularABSTRACT
In response to accidental oil spills at sea, chemical oil dispersants are utilized to limit negative impacts on nearby littoral zones. However, current evidence suggests that such dispersants may be toxic to aquatic organisms. Blue mussels (Mytilus edulis) and giant scallops (Placopecten magellanicus) were exposed to different environmentally relevant concentrations of oil dispersant and their behavioural responses were closely monitored using high frequency (10Hz) valvometry. Behavioural valve responses included rapid closures when oil dispersant was added to the experimental tanks. At higher concentrations, the mussels remained closed throughout the exposure period. The giant scallop displayed escape behaviours (clapping) prior to mortality, suggesting toxicity of the oil dispersant. Relationships between different behavioural indicators and oil dispersant concentrations were observed for both species, but with different trends. While scallops demonstrated positive correlations between gaping behaviours and dispersant concentration, mussels exhibited a concentration threshold beyond which the gaping behaviour was characteristic of longer closure periods. This study highlights behavioural response differences consistent with bivalve-specific biological traits: the continuous valve closure of an intertidal species, M. edulis, firmly attached to the substrate, and the escapement behaviours of a semi-mobile subtidal species, P. magellanicus. From these observations, it appears that valvometry could be used as a tool for environmental assessments.
Subject(s)
Mytilus edulis/drug effects , Pectinidae/drug effects , Surface-Active Agents/toxicity , Water Pollutants, Chemical/toxicity , Animals , Arctic Regions , Behavior, Animal/drug effects , Mytilus edulis/physiology , Pectinidae/physiology , Petroleum PollutionABSTRACT
Arctic regions are highly impacted by climate change and are characterized by drastic seasonal changes in light intensity and duration with extended periods of permanent light or darkness. Organisms use cyclic variations in light to synchronize daily and seasonal biological rhythms to anticipate cyclic variations in the environment, to control phenology and to maintain fitness. In this study, we investigated the diel biological rhythms of the Arctic scallop, Chlamys islandica, during the autumnal equinox and polar night. Putative circadian clock genes and putative light perception genes were identified in the Arctic scallop. Clock gene expression oscillated in the three tissues studied (gills, muscle, mantle edge). The oscillation of some genes in some tissues shifted from daily to tidal periodicity between the equinox and polar night periods and was associated with valve behaviour. These results are the first evidence of the persistence of clock gene expression oscillations during the polar night and might suggest that functional clockwork could entrain rhythmic behaviours in polar environments.
Subject(s)
Circadian Clocks/genetics , Pectinidae/physiology , Animals , Arctic Regions , Circadian Rhythm , Darkness , LightABSTRACT
Inspired by a scallop's strong underwater propulsion mechanism, we designed and prototyped a scallop robot capable of clapping and swimming. In this work, an artificial velum was used to work as a check valve to stimulate the robot's swimming. A couple of supporting plates were fixed on the robot shells to achieve the modulation of clapping process of the shells. The scallop robot can move at a maximum average and instantaneous speed of 3.4 and 4.65 body lengths per second, respectively. The effect of the supporting plates, the artificial velum, as well as the clapping frequency and amplitude on the swimming performance of the scallop robot was also experimentally evaluated. By tuning the sizes of the jet apertures, the scallop robot is capable of achieving high mobility actions such as turning. We also obtained the aperture ratio with the corresponding turning radius. This scallop robot provides a new propulsion mechanism in underwater bionic robots; it is also of help to understand the swimming principle of scallops in terms of jet propulsion and clapping motion.
Subject(s)
Pectinidae/physiology , Robotics/instrumentation , Animals , Biomechanical Phenomena , Biomimetic Materials , Equipment Design , Hydrodynamics , SwimmingABSTRACT
In marine ectotherms, reproduction is an energetically expensive process that affects their thermal window tolerance. For most species, the impacts of hyperthermia during gametogenesis have still not been addressed. Our aim was to assess the metabolic response of adult Nodipecten subnodosus scallops to thermal challenges at early development (spring) and advanced gonad maturation (summer). Scallops collected in both seasons were exposed to acute hyperthermia (26 and 30 °C, 24 h), maintaining a group of scallops at acclimation temperature (22 °C) as a control condition. During the summer, relatively low activity of hexokinase (HK), as well as low levels of ATP and GTP were found in the adductor muscle, suggesting a shift in energy investment for reproduction, although arginine phosphate (ArgP) levels were higher in summer scallops. Hyperthermia (30 °C) induced an increased energy expenditure reflected by a transitory enhanced oxygen consumption (VO2) and relatively high activities of HK and arginine kinase (AK). Moreover, a slight decrease in adenylic energy charge (AEC) was partially compensated by a decrease in ArgP. An increase in nucleotide by-products inosine monophosphate (IMP) and hypoxanthine (HX) indicated a thermal stress at 30 °C. Some of the responses to acute hyperthermia were more pronounced at advanced maturation stages (summer scallops), indicating a possible lack of energy balance, with possible implications in animals challenged to global warming scenario.
Subject(s)
Pectinidae/physiology , Adenosine Triphosphate/metabolism , Animals , Energy Metabolism , Female , Gametogenesis , Guanosine Triphosphate/metabolism , Heat-Shock Response , Hexokinase/metabolism , Hot Temperature , Male , Oxygen Consumption , Pectinidae/enzymology , Reproduction , SeasonsABSTRACT
Perkinsus mediterraneus is a protozoan parasite that can cause marine mollusc diseases known as perkinsosis being a serious threat for clam cultures worldwide. The aim of the present study was first to determine the Perkinsus species infecting the variegated scallop Mimachlamys varia and then to evaluate the existence of oxidative stress in gills of M. varia according to different degrees of infection. DNA sequencing confirmed that P. mediterraneus was the species infecting M. varia. ROS production was progressively increasing with the degree of infection although the differences were only significant in the high-infected group. Low degree of infection significantly increased superoxide dismutase (SOD) and glutathione S-transferase (GST) activities and nitrite levels with respect to the control group. In the high-infected group, a significant increase was evidenced in all analysed enzymes, catalase, SOD, glutathione reductase and GST. Non-significant differences in MDA levels were observed between the control and low-infected groups; however, a significant increase in MDA levels was observed in the high-infected group. In conclusion, the infection by Perkinsus mediterraneus in M. varia induces oxidative stress and an antioxidant response directly related to the infection degree that can contribute to the pathogenicity of the infection.
Subject(s)
Alveolata/physiology , Antioxidants/metabolism , Malondialdehyde/metabolism , Nitrites/metabolism , Oxidative Stress , Pectinidae/parasitology , Animals , Pectinidae/physiology , SpainABSTRACT
Noble scallop, an economically important edible marine bivalve displays polymorphism in shells (golden and brown) and flesh colors (orange and white). Mass mortality of noble scallops usually occurs during the winter months. Interestingly, carotenoid-rich golden scallops demonstrated much higher survival rates than brown scallops in winter. In order to understand the response of polymorphic noble scallops to sequential cold stress, the present study aimed to investigate the enzyme and non-enzymatic antioxidant responses of golden and brown scallops under sequential cold stress. Parameters evaluated included total carotenoid content (TCC), fatty acid composition, total antioxidant capacity (TAC), methylenedioxyamphetamine (MDA) content, catalase (CAT) activity, and superoxide dismutase (SOD) enzyme activity. The results of the present study revealed that golden scallops have higher cold tolerance than brown scallops. Golden and brown scallops are well adapted to low water temperature of above 12 °C, but in areas where winter water temperatures are below 12 °C, golden scallops are more suitable for aquaculture than brown scallops. The findings of this study are crucial to understanding the physiological responses of polymorphic scallops to cold stress and identify suitable candidates for winter aquaculture.
Subject(s)
Carotenoids/analysis , Cold-Shock Response , Pectinidae/enzymology , Pectinidae/physiology , Animals , Antioxidants , Aquaculture , Catalase/analysis , Fatty Acids/analysisABSTRACT
Microplastics are a growing problem in marine environments due to their ubiquitous occurrence and affinity for chemical pollutants. However, the influence of microplastics on the uptake, depuration and toxicity of decabromodiphenyl ether (BDE-209) in marine organisms is unclear. We exposed the marine scallop Chlamys farreri to polystyrene microplastics (PS; 125 µg/L) combined with BDE-209 (10 and 100 µg/L) to determine their toxicokinetics, cellular toxicity and histopathological effects. The results showed that PS acted as both a carrier and a scavenger for the bioaccumulation of BDE-209. Importantly, the carrier role of PS was greater than scavenger one. PS increased the negative effect of BDE-209 (100 µg/L) on hemocyte phagocytosis, and ultrastructural changes in gills and digestive gland of scallops due to their carrier role for the bioaccumulation of BDE-209. However, PS did not increase the DNA damage of BDE-209 on the hemocytes. These findings are evidence of microplastics transferring adsorbed pollutants to marine organisms, and increasing their toxicity.
Subject(s)
Halogenated Diphenyl Ethers/toxicity , Microplastics/toxicity , Pectinidae/physiology , Water Pollutants, Chemical/toxicity , Animals , Plastics , PolystyrenesABSTRACT
Ocean acidification and increased ocean temperature from elevated atmospheric carbon dioxide can significantly influence the physiology, growth and survival of marine organisms. Despite increasing research efforts, there are still many gaps in our knowledge of how these stressors interact to affect economically and ecologically important species. This project is the first to explore the physiological effects of high pCO2 and temperature on the acclimation potential of the purple-hinge rock scallop (Crassadoma gigantea), a widely distributed marine bivalve, important reef builder, and potential aquaculture product. Scallops were exposed to two pCO2 (365 and 1050 µatm) and temperature (14 and 21.5⯰C) conditions in a two-factor experimental design. Simultaneous exposure to high temperature and high pCO2 reduced shell strength, decreased outer shell density and increased total lipid content. Despite identical diets, scallops exposed to high pCO2 had higher content of saturated fatty acids, and lower content of polyunsaturated fatty acids suggesting reorganization of fatty acid chains to sustain basic metabolic functions under high pCO2. Metagenomic sequencing of prokaryotes in scallop tissue revealed treatment differences in community composition between treatments and in the presence of genes associated with microbial cell regulation, signaling, and pigmentation. Results from this research highlight the complexity of physiological responses for calcifying species under global change related stress and provide the first insights for understanding the response of a bivalve's microbiome under multiple stressors.
Subject(s)
Acids/chemistry , Bone and Bones/metabolism , Carbon Dioxide/analysis , Microbiota , Pectinidae/physiology , Seawater/microbiology , Temperature , Acclimatization , Animal Shells , Animals , Global Warming , Homeostasis , Hydrogen-Ion Concentration , Pectinidae/microbiologyABSTRACT
The development of human activities on French Atlantic coastlines (La Rochelle) lead to chronic pollution of the environment by organic (pesticides, hydrocarbons, agrochemicals) and inorganic (heavy metals) contaminants. These past years, several regulations have been implemented to preserve coastal environments. The purpose of this study was to perform biomonitoring of bivalve species using an outdoor caging technique. The goal of our work was to assess the impact of harbour's trace elements on the state of health of the marine bivalve Mimachlamys varia. First, various molecular defence biomarkers were measured: SOD (oxidative stress), GST (detoxification process), MDA (lipid peroxidation), and Laccase (immune reaction). Thus, in April 2016, scallops were collected at three caging sites, which differ by their levels of pollution, after transplantation into port areas (fairing, rainwater) and a control site (marsh). Bivalve samples were taken at three sampling dates (D0, D07, D21). Biomarker assays were performed in the digestive glands due to their bioaccumulation properties. The second aim was to explore the impacts of inorganic pollutants placed in environmental harbour's sites. After 21 days, the biomarker response of transplanted bivalves revealed a SOD decrease, Laccase and GST stimulations, higher concentrations in Cu, Fe, As, Co, Mn, Zn, Sn and no significant variation of MDA concentration. Our ecological relevance of biomarker approaches opens interesting perspectives to identify M. varia such as a pertinent marine sentinel species. The several selected biomarkers determined could confirm their ability to appraise the water quality of hydro-systems located in French coastlines, such as port areas.
Subject(s)
Biological Monitoring/methods , Pectinidae/physiology , Water Pollution/statistics & numerical data , Animals , Biomarkers/metabolism , Bivalvia/metabolism , France , Human Activities , Humans , Hydrocarbons , Lipid Peroxidation , Metals, Heavy/analysis , Oxidative Stress , Pesticides , Trace Elements/analysis , Water Pollutants, Chemical/analysisABSTRACT
The noble scallop Chlamys nobilis is an important edible marine bivalve that is widely cultivated in the sea of southern China. Unfortunately, the mass mortality of noble scallops frequently occurs during the winter months. The present study investigated the effects of acute cold stress (8⯰C) to the physiological responses of polymorphic noble scallops, by assessing the HSP70 gene expression, total carotenoid content (TCC), total antioxidant capacity (TAC), malondialdehyde (MDA) content, catalase (CAT) activity and superoxide dismutase (SOD) enzymatic activity in different tissues of golden and brown scallops. The results of the present study revealed that MDA, TCC and CAT increased drastically in most tissues in the early stage of acute cold stress (0-3â¯h), but TCC, SOD and CAT generally showed a downward trend. Within 3-6â¯h of acute cold stress, MDA content decreased in most tissues and the SOD content increased significantly in most tissues, while TCC and CAT remained at peak. After 6â¯h of acute cold stress, MDA content continued to increase in most tissues, while TCC, CAT, SOD and TAC decreased or remained at a lower level. For HSP70 expression, up-regulation of the HSP70 gene was observed only in mantle of brown scallops and hemolymph of golden scallops at 3â¯h and 24â¯h, respectively. The findings of the present study can better understand the physiological response of noble scallops to acute cold stress.
Subject(s)
Carotenoids/metabolism , Cold Temperature/adverse effects , Immunity, Innate/physiology , Oxidative Stress/physiology , Pectinidae/physiology , Animals , Antioxidants/metabolism , Fish Proteins/metabolism , Gene Expression , Immunity, Innate/genetics , Pectinidae/immunologyABSTRACT
BACKGROUND: The Yesso scallop, Patinopecten (Mizuhopecten) yessoensis, is a commercially important bivalve in the coastal countries of Northeast Asia. It has complex modes of sex differentiation, but knowledge of the mechanisms underlying this sex determination and differentiation is limited. RESULTS: In this study, the gonad tissues from females and males at three developmental stages were used to investigate candidate genes and networks for sex differentiation via RNA-Req. A total of 901,980,606 high quality clean reads were obtained from 18 libraries, of which 417 expressed male-specific genes and 754 expressed female-specific genes. Totally, 10,074 genes differentially expressed in females and males were identified. Weighted gene co-expression network analysis (WGCNA) revealed that turquoise and green gene modules were significantly positively correlated with male gonads, while coral1 and black modules were significantly associated with female gonads. The most important gene for sex determination and differentiation was Pydmrt 1, which was the only gene discovered that determined the male sex phenotype during early gonadal differentiation. Enrichment analyses of GO terms and KEGG pathways revealed that genes involved in metabolism, genetic and environmental information processes or pathways are sex-biased. Forty-nine genes in the five modules involved in sex differentiation or determination were identified and selected to construct a gene co-expression network and a hypothesized sex differentiation pathway. CONCLUSIONS: The current study focused on screening genes of sex differentiation in Yesso scallop, highlighting the potential regulatory mechanisms of gonadal development in P. yessoensis. Our data suggested that WCGNA can facilitate identification of key genes for sex differentiation and determination. Using this method, a hypothesized P. yessoensis sex determination and differentiation pathway was constructed. In this pathway, Pydmrt 1 may have a leading function.
Subject(s)
Gene Expression Profiling , Gene Regulatory Networks , Pectinidae/genetics , Pectinidae/physiology , Sex Differentiation/genetics , Animals , Sequence AnalysisABSTRACT
OBJECT: Dynamic in vivo31P-NMR spectroscopy in combination with Magnetic Resonance Imaging (MRI) was used to study muscle bioenergetics of boreal and Arctic scallops (Pecten maximus and Chlamys islandica) to test the hypothesis that future Ocean Warming and Acidification (OWA) will impair the performance of marine invertebrates. MATERIALS & METHODS: Experiments were conducted following the recommendations for studies of muscle bioenergetics in vertebrates. Animals were long-term incubated under different environmental conditions: controls at 0⯰C for C. islandica and 15⯰C for P. maximus under ambient PCO2 of 0.039â¯kPa, a warm exposure with +5⯰C (5⯰C and 20⯰C, respectively) under ambient PCO2 (OW group), and a combined exposure to warmed acidified conditions (5⯰C and 20⯰C, 0.112â¯kPa PCO2, OWA group). Scallops were placed in a 4.7â¯T MR animal scanner and the energetic status of the adductor muscle was determined under resting conditions using in vivo31P-NMR spectroscopy. The surplus oxidative flux (Qmax) was quantified by recording the recovery of arginine phosphate (PLA) directly after moderate swimming exercise of the scallops. RESULTS: Measurements led to reproducible results within each experimental group. Under projected future conditions resting PLA levels (PLArest) were reduced, indicating reduced energy reserves in warming exposed scallops per se. In comparison to vertebrate muscle tissue surplus Qmax of scallop muscle was about one order of magnitude lower. This can be explained by lower mitochondrial contents and capacities in invertebrate than vertebrate muscle tissue. Warm exposed scallops showed a slower recovery rate of PLA levels (kPLA) and a reduced surplus Qmax. Elevated PCO2 did not affected PLA recovery further. CONCLUSION: Dynamic in vivo31P-NMR spectroscopy revealed constrained residual aerobic power budgets in boreal and Arctic scallops under projected ocean warming and acidification indicating that scallops are susceptible to future climate change. The observed reduction in muscular PLArest of scallops coping with a warmer and acidified ocean may be linked to an enhanced energy demand and reduced oxygen partial pressures (PO2) in their body fluids. Delayed recovery from moderate swimming at elevated temperature is a result of reduced PLArest concentrations associated with a warm-induced reduction of a residual aerobic power budget.
Subject(s)
Energy Metabolism , Magnetic Resonance Spectroscopy , Muscle, Skeletal/metabolism , Pectinidae/physiology , Algorithms , Animals , Invertebrates , Mitochondria, Muscle/metabolism , Oceans and Seas , Phosphorus , Swimming , TemperatureABSTRACT
Light levels in terrestrial and shallow-water environments can vary by ten orders of magnitude between clear days and overcast nights. Light-evoked pupillary responses help the eyes of animals perform optimally under these variable light conditions by balancing trade-offs between sensitivity and resolution [1]. Here, we document that the mirror-based eyes of the bay scallop Argopecten irradians and the sea scallop Placopecten magellanicus have pupils that constrict to â¼60% of their fully dilated areas within several minutes of light exposure. The eyes of scallops contain two separate retinas and our ray-tracing model indicates that, compared to eyes with fully constricted pupils, eyes from A. irradians with fully dilated pupils provide approximately three times the sensitivity and half the spatial resolution at the distal retina and five times the sensitivity and one third the spatial resolution at the proximal retina. We also identify radial and circular actin fibers associated with the corneas of A. irradians that may represent muscles whose contractions dilate and constrict the pupil, respectively.
Subject(s)
Ocular Physiological Phenomena/radiation effects , Pectinidae/physiology , Animals , Eye/radiation effects , Pectinidae/radiation effectsABSTRACT
As lipid microconstituents mainly of plant origin, carotenoids are essential nutrients for humans and animals, and carotenoid coloration represents an important meat quality parameter for many farmed animals. Currently, the mechanism of carotenoid bioavailability in animals is largely unknown mainly due to the limited approaches applied, the shortage of suitable model systems and the restricted taxonomic focus. The mollusk Yesso scallop (Patinopecten yessoensis) possessing orange adductor muscle with carotenoid deposition, provides a unique opportunity to research the mechanism underlying carotenoid utilization in animals. Herein, through family construction and analysis, we found that carotenoid coloration in scallop muscle is inherited as a recessive Mendelian trait. Using a combination of genomic approaches, we mapped this trait onto chromosome 8, where PyBCO-like 1 encoding carotenoid oxygenase was the only differentially expressed gene between the white and orange muscles (FDRâ¯=â¯2.75E-21), with 11.28-fold downregulation in the orange muscle. Further functional assays showed that PyBCO-like 1 is capable of degrading ß-carotene, and inhibiting PyBCO-like 1 expression in the white muscle resulted in muscle coloration and carotenoid deposition. In the hepatopancreas, which is the organ for digestion and absorption, neither the scallop carotenoid concentration nor PyBCO-like 1 expression were significantly different between the two scallops. These results indicate that carotenoids could be taken up in both white- and orange-muscle scallops and then degraded by PyBCO-like 1 in the white muscle. Our data suggest that PyBCO-like 1 is the essential gene for carotenoid metabolism in scallop muscle, and its downregulation leads to carotenoid deposition and muscle coloration.
Subject(s)
Muscle, Skeletal/enzymology , Oxygenases/metabolism , Pectinidae/enzymology , Animals , Carotenoids/analysis , Carotenoids/metabolism , Chromosomes , Color , Oxygenases/genetics , Pectinidae/physiologyABSTRACT
Benzotriazole and its associated derivatives (BTs) are widely used as ultraviolet stabilizers and corrosion inhibitors. They have been extensively found in marine environments and are bioaccumulative through the food chain. However, the toxicities of BTs to marine organisms are seldom identified and no assessment has been conducted for filter-feeding bivalves. In this study, a marine scallop Chlamys nobilis was exposed to 0, 0.01, 0.1, and 1.0 mg/L of BT for 60 days. Effects of BT on endocrine system, cytochrome P450 activity, antioxidant activity, and neural activity of C. nobilis were examined. The results showed that BT exerted significant estrogenic effects on both male and female scallops and inhibited EROD activities of C. nobilis even at 0.01 mg/L level. BT at ≥ 0.01 mg/L levels also caused significant oxidative stress on C. nobilis. Moreover, most of the adverse effects of BT to C. nobilis were found from day 35 and 0.01 mg/L was the lowest concentration with observed effects, showing the long-term toxic effects of BT to C. nobilis. Thus, the adverse effects of BT and its derivatives to marine benthic communities deserve more attention in future research.