Razor Clam Research Articles

POPULATION STRUCTURE AND REPRODUCTION OF THE RAZOR CLAMS Solen lamarckii (Chenu, 1843) IN THE INTERTIDAL ZONE OF API API VILLAGE WATERS, BENGKALIS REGENCY

Razor clam (Solen lamarckii) is a type of pelecypoda that has high economic value on the Api api village waters, Bengkalis Regency. This research aims to study the population structure and reproduction of razor clam. The study was carried out over 2 month period from September to October 2019 at Api api village waters, Bengkalis Regency. Razor clam samples were collected by using a 1 x 1 m2 frame that laid along transect. There were 5 plots and 5 subplots along the transect as replications. The result showed, the population density of razor clams is 3.12 species/m2 in September and 2.88 species/m2 in October 2019. The distribution pattern of razor clams was uniform. While, the most common size of razor clam is the medium size category (40-60 mm) both in September and in October 2019. The average value of gonado somatic index (GSI) was 2.28-8.60%. Histological analysis indicated that maturity gonad stage of razor clam was commonly found in September is maturity gonad stage I (60%), while in October is stage III (40%) and stage IV(30%).

Microplastic Exposure by Razor Clam Recreational Harvester-Consumers Along a Sparsely Populated Coastline

Microplastics (MPs) are anthropogenic contaminants found in coastal and marine environments worldwide. Pacific razor clams (Siliqua patula), important for local indigenous culture, economy, gastronomy and food security along the United States West Coast, are subjected to myriad environmental stressors including predation, storm events, disease, toxins, and MPs. This study aimed to determine MP burdens in Olympic Coast, Washington Pacific razor clams and estimate annual MP exposure of recreational razor clam harvester-consumers from eating this species. We quantified suspected MP burdens in Pacific razor clams collected from eight tribal, recreational, and commercial harvest areas on the Olympic Coast in April 2018. We administered questionnaires to 107 recreational razor clam harvesters during the same timeframe to determine consumption patterns, preparation styles, knowledge and concerns about MPs, and demographics. Razor clams containing suspected MPs, primarily microfibers, were found at all eight sites. Average suspected MP burden differed by sample type (whole = 6.75 ± 0.60, gut-tissue = 7.88 ± 0.71, non-gut tissue = 4.96 ± 0.56, and cleaned samples = 3.44 ± 0.25). FTIR analyses of a random subset of microfiber-type MPs in whole and cleaned clams indicated material types of polyethylene terephthalate, cellulose acetate, cellophane, polyester, nylon, and cellulose. The average number of razor clams consumed per meal by Olympic Coast recreational razor clam harvesters was 4.27 ± 0.27, which varied by gender and ethnicity, but not income or age. Harvesters ate 0–209 meals/year of razor clams (16.2% harvested but did not eat razor clams), and most respondents (88.3%) fully cleaned razor clams before consuming them. Annual suspected MP exposure for razor clam harvester-consumers was 60–3,070 for cleaned and 120–6,020 for whole clams. Our findings suggest Olympic Coast recreational razor clam harvester-consumers are exposed to low levels of MPs from eating razor clams. MP exposure can be reduced by roughly 50% if clams are cleaned before consumption. Our work serves as an important reference in the growing portfolio of Pacific Northwest microplastic research, to inform future MP attenuation recommendations and development of human health standards for this type of pollution.

Characteristic Nest Angelwing Clam (Pholas orientalis Gmelin, 1791) in the Area of Kelang Beach

A clam angelwing is one kind of razor clam. His life Habitat is found in the Kelang Beach district of Serdang Bedagai, North Sumatera Province. The purpose of this research is to know the characteristics of tembarang shell nests. This research is an exploratory, discrete study. The findings Data are narrated and discussed based on the relevant literature review. Based on the findings in the field, the characteristics of the nest angelwing clam are listed as follows: Distance from the shoreline between 30-70 meters, The diameter of the nest length is 0.5-1.5 cm and the width is 0.3-1 cm, the holes are round and round oval, usually holes consist of 1-5 pieces. Hole depth 10-40 cm, on the surface of the hole there are shavings or piles of sand, and 1 hole filled 1 individual. Average water quality observation during research: water temperature (29-30 °C), Water brightness (25-40 cm), water pH (7,5-7,9), dissolved oxygen (5,6-5,9 ppm), and salinity (29-30 ppt).

The razor clam Sinonovacula constricta uses the strategy of conversion of toxic ammonia to glutamine in response to high environmental ammonia exposure.

High ammonia can inhibit the survival and growth, and even cause mortality of razor clam (S. constricta). The accumulation of ammonia to lethal concentrations in some invertebrates may be partially prevented by converting some of the ammonia into glutamine (Gln). Glutamine dehydrogenase (GDH) and glutamine synthetase (GS) have been widely implicated a central role in response to ammonia stress. However, the molecular and physiological response of GDH and GS to ammonia alterations has not yet been determined in clams. To investigate the possible participatory role of GDH and GS genes in altered ammonia conditions, we have cloned their gene sequences and examined the mRNA expression and western blotting under ammonia exposure in S. constricta (ScGDH and ScGS), and detected the levels of GS and GDH, and the content of glutamate (Glu) and Gln. The full-length cDNA of ScGDH was 3924bp, with a 1629bp open reading frame (ORF) encoding a 542 amino-acid polypeptide. The complete cDNA sequence for ScGS had 2739bp with an ORF of 1110bp encoding 369 amino acids. To investigate ammonia detoxification strategies, the clams were exposed to ammonia for 96h at four different concentrations (0, 100, 140, and 180mg/L). Exposure to ammonia resulted in a significant increase of glutamate concentration and Gln in the haemocytes. GDH activity, GDH relative mRNA and protein expression, GS activity, GS relative mRNA and protein expression increased significantly and showed a pronounced time and dosage interaction in the liver. The results suggested that the protective strategies of Gln formation existed in S. constricta, which could convert ammonia to non- or less toxic nitrogenous compounds on the exposure of ammonia. Glutamate content in the haemocytes increased significantly, which is to ensure sufficient Glu to meet the needs for GS to catalyze the conversion of ammonia to Gln. We proposed that the induction of Glu synthesis-related genes and the subsequent formation of the active protein occurred in preparation for the increased capacity of the body to convert ammonia, into Gln. The results of this study suggested that GDH and GS play an important role in the synthesis of Gln, emphasizing, the protective strategies of Gln formation in S. constricta convert ammonia to nontoxic or less toxic nitrogenous compounds upon exposure to ammonia.

KARAKTERISTIK HABITAT DAN STRUKTUR POPULASI KERANG BAMBU (Solen lamarckii, Chenu 1984) DI ZONA INTERTIDAL DESA APIAPI KECAMATAN BANDAR LAKSAMANA KABUPATEN BENGKALIS

The study about habitat characteristics and population structure razor clam (Solen lamarckii, Chenu 1984) in intertidal zone Apiapi Village Bandar Laksamana District Bengkalis Regency conducted on January 2020. The purpose of this study was to analyze about habitat characteristics and population structure of razor clam and the correlation between substrate particle size and population density of razor clam. The habitat parameters measured include the physical and chemical parameters of sea waters. Determination of the station using purposive sampling method. Razor clam samples were collected by using a 1 x 1 m2 frame that laid along a transect. There were 4 plots and 3 subplots along the transect as replications. The result showed, the sediment tipe was sandy substrate, organic material was low, total suspended solid was high. Population density of razor clams was 3.3-23.3 Ind/m2. The distribution pattern of razor clams through each plot was uniform. While, the most common size of razor clam 5.04-5.62 cm. The correlation between particle size and population density of razor clam was strong.

RNAi-mediated knock-down of the dopamine beta-hydroxylase gene changes growth of razor clams

Dopamine beta-hydroxylase (DβH) plays an essential role in the synthesis of catecholamines (CA) in neuroendocrine networks. In the razor clam, Sinonovacula constricta a novel gene for DβH (ScDβH-α) was identified that belongs to the copper type II ascorbate-dependent monooxygenase family. Expression analysis revealed ScDβH-α gene transcripts were abundant in the liver and expressed throughout development. Knock-down of ScDβH-α in adult clams using siRNA caused a reduction in the growth rate compared to control clams. Reduced growth was associated with strong down-regulation of gene transcripts for the growth-related factors, platelet derived growth factors A (PDGF-A) (P<0.001) 24h after ScDβH-α knock-down, vascular endothelial growth factor (VEGF1) (P<0.001) and platelet derived growth factor B (PDGF-B-2) (P<0.001) 24h and 48h after ScDβH-α knock-down and transforming growth factor beta (TGF-β1) (P<0.001) 48h and 72h after ScDβH-α knock-down. Taken together the results suggest that the novel ScDβH-α gene through its role in CA synthesis is involved in growth regulation in the razor clam and possibly other bivalves.

Biochemical adaptations of the stout razor clam (Tagelus plebeius) to changes in oxygen availability: resilience in a changing world?

Climate change is producing sea level rise and deoxygenation of the ocean, altering estuaries and coastal areas. Changes in oxygen availability are expected to have consequences on the physiological fitness of intertidal species. In this work we analyze the coping response of the intertidal stout razor clam (Tagelus plebeius (Lightfoot, 1786)) to extreme environmental changes in oxygen concentration. Their biochemical responses to normoxia, hypoxia, and hyperoxia transition at different intertidal level (low–high) were measured through an in situ transplant experiment. The high intertidal level negatively affected the analyzed traits of the T. plebeius populations. The differences in reactive oxygen species production, total oxyradical scavenger capacities, and catalase activity also suggested more stressful conditions at the high level where long-term hypoxia periods occur. Both hypoxia and re-oxygenation provoked re-adjustments in the antioxidant responses and higher lipid oxidative damage (normoxia &lt; hypoxia &lt; re-oxygenation). The observed responses in transplanted clams at the opposite intertidal level suggested the potential acclimation of T. plebeius to cope with new environmental conditions. These findings are discussed within a global changing context where both increasing deoxygenation conditions and sea level rise are predicted to be exacerbated in the area driven by climate change.

Inland alkaline brackish water aquaculture of juvenile razor clam: Survival, growth, physiology and immune responses

In this study, we investigated rearing and breeding razor clam (Sinonovacula constricta) in inland alkaline brackish water. During 45 days of the experiment in candidate target inland area brackish water (TBW), survival, growth, enzyme activity and immune responses were analysed. The results showed that shell length and weight were significantly inhibited in the TBW group (p <0.001). Although the cumulative mortality was 81.479 ± 7.028 (p < 0.001) at 15 days, it increased slowly to 92.915 ± 2.271 (p < 0.001) at 45 days. The enzyme activities of Na+/K+-ATPase, aspartate aminotransferase and superoxide dismutase peaked at 15 days, and juvenile S. constricta (JSC) may engaged in partial anaerobic metabolism or damage to gill tissue, which may explain the high mortality rate at this time. Additionally, the phagocytic ability of haemocytes was inhibited (p < 0.001), but the metabolic activity was enhanced (p < 0.001). This implies that 15 days was the peak of TBW stress, and stress gradually decreased by days 30 and 45. TBW affected metabolism, osmotic regulation, and immune responses. There was an independent ionic interaction perhaps effect on JSC, primarily through Na+/K+ rate. Approximately 7 % of animals adapted successfully to TBW after 45 days. In summary, S. constricta has a great potential in further anti-TBW conditions selective breeding research.

Integrated mRNA and Small RNA Sequencing Reveals Regulatory Expression of Larval Metamorphosis of the Razor Clam

The razor clam, Sinonovacula constricta, is an important economic marine shellfish, and its larval development involves obvious morphological and physiological changes. MicroRNA plays a key role in the physiological changes of the organism through regulating targeted mRNA. This study performed miRNA-mRNA sequencing for eight different developmental stages of S. constricta using Illumina sequencing. A total of 2156 miRNAs were obtained, including 2069 known miRNAs and 87 novel miRNAs. In addition, target genes were predicted for key miRNAs differentially expressed between adjacent development samples by integrating the mRNA transcriptome. Further analysis revealed that the differentially expressed genes were enriched in complement activation, alternative pathways, translation, and negative regulation of monocyte molecular protein-1 production. KEGG pathway annotation showed significant enrichment in the regulation of the ribosome, phagosome, tuberculosis and fluid shear stress, and atherosclerosis. Ten mRNAs and ten miRNAs that are related to larval metamorphosis were identified using real-time PCR. Furthermore, the double luciferase experiment validated the negative regulatory relationship between miR-133 and peroxisome proliferator-activated receptor-γ (PPAR-γ). These results indicated that the target genes regulated by these differentially expressed miRNAs may play an important regulatory role in the metamorphosis development of S. constricta.

Multifaceted Bioinspiration for Improving the Shaft Resistance of Deep Foundations

This paper describes the bioinspiration process to derive design concepts for new deep foundation systems that have greater axial capacity per unit volume of pile material compared to conventional deep foundations. The study led to bioinspired ideas that provide greater load capacity by increasing the pile shaft resistance. The bioinspiration approach used problem-solving strategies to define the problem and transfer strategies from biology to geotechnical engineering. The bioinspiration considered the load transfer mechanism of hydroskeletons and the anchorage of the earthworm, razor clam, kelp, and lateral roots of plants. The biostrategies that were transferred to the engineering domain included a flexible but incompressible core, passive behaviour against external loading, a longitudinally split shell that allows expansion for anchorage, and lateral root-type or setae-type anchoring elements. The concepts of three bioinspired deep foundation systems were proposed and described. The advantage of this approach was illustrated with two examples of the new laterally expansive pile in drained sand under axial compression. The finite element analysis of these examples showed that the new laterally expansive pile can provide considerably greater load capacity compared to a conventional cylindrical pile due to the increased lateral confining pressure developed along the expanded pile core.

A Potential Role of Bone Morphogenetic Protein 7 in Shell Formation and Growth in the Razor Clam Sinonovacula constricta.

Bone morphogenetic proteins (BMPs) not only play essential roles in bone development but also are involved in embryonic growth, organogenesis cell proliferation and differentiation. However, the previous studies on the functions of shellfish BMPs genes are still very limited. To better understand its molecular structure and biological function, BMP7 of the razor clam Sinonovacula constricta (Sc-BMP7) was cloned and characterized in this study. The full length of Sc-BMP7 is 2252 bp, including an open reading frame (ORF) of 1257 bp encoding 418 amino acids. The protein sequence included a signal peptide (1–32 aa), a prodomain (38–270 aa) and a TGF-β domain (317–418 aa). The quantitative expression of eleven adult tissues showed that Sc-BMP7 was significantly higher expressed in the gill, foot, and mantle (P < 0.05), but lower in hemocytes and hepatopancreas. In the early development stages, low expression was detected in the stages of unfertilized mature eggs, fertilized eggs, 4-cell embryos, blastula, gastrulae, whereas it increased after the stage of trochophore and demonstrated the highest expression in umbo larvae (P < 0.01). In shell repair experiment, Sc-BMP7 showed increasing expression level after 12 h. The higher expression of Sc-BMP7 was detected while Ca2+ concentration was reduced in seawater. After inhibiting Sc-BMP7 expression using RNA interference (RNAi) technology, expression of Sc-BMP7 mRNA and protein were significantly down-regulated (P < 0.05) in the central zone of mantle (nacre formation related tissue) and the pallial zone of mantle (prismatic layer formation related tissue). Association analysis identified two shared SNPs in exon of Sc-BMP7 gene from 246 individuals of two groups. These results indicated that BMP7 might be involved in shell formation and growth. These results would contribute to clarify the role of Sc-BMP7 in the regulation of growth and shell formation, and provide growth-related markers for molecular marker assisted breeding of this species.

Classification and morphology of circulating haemocytes in the razor clam Sinonovacula constricta

The razor clam Sinonovacula constricta is widely distributed in the intertidal zones and estuarine waters along the coast of western Pacific Ocean and is extensively cultured. Even though haemocytes are known to play an important role in the immune mechanisms of bivalves, these cells are poorly studied in S. constricta. We researched the morphology and immunological activities of haemocytes in S. constricta using light and electron microscopy and flow cytometry. Three major subpopulations of haemocytes were identified in the haemolymph: granulocytes, semigranulocytes, and hyalinocytes. These subpopulations were divided using flow cytometry, but not satisfactorily. Therefore, the flow cytometry findings were combined with the light and electron microscopy findings, as well as Percoll density-gradient centrifugation findings, to classify and distinguish between the cell types more effectively. The combined findings showed that granulocytes was larger cells, while semigranulocytes was smaller and more abundant. Further, granulocytes had numerous granules in the cytoplasm, semigranulocytes contained fewer and smaller granules, and hyalinocytes was smaller and less abundant with no or a few granules. Both granulocytes and semigranulocytes had greater phagocytotic activity and a higher lysosomal content than hyalinocytes. The results declared that granulocytes and semigranulocytes were the main haemocytes involved in the cellular defence mechanism in S. constricta.

Frozen kinetics models for sensory, chemical, and microbial spoilage of preserved razor clam (Sinonovacula constricta) at different temperatures

Abstract Refrigerated treatment offers an effective avenue to delay spoilage process of aquatic products during storage, while none or less study has been reported for bivalve species. This work aims to investigate the variations in different storage freshness of frozen razor clam samples, by which an effective evaluation system based on frozen kinetics models was established. In this study, fresh razor clam samples were preserved at the temperature of 268, 258, and 248 K for 40 days, respectively. The spoilage process was determined by a series of freshness assays, including sensory score (SS), electric conduction (EC), total volatile basic nitrogen (TVB-N), K-value, and total colonies counts (TCC). On this basis, the variations in these indexes were fitted by zero-, first- and second- order kinetic models. Results showed that zero -order kinetic model was more suitable to fit each freshness trend. Accordingly, the shelf life of razor clam was predicted as 47∼54, 79∼84, and 121∼154 days when the samples were preserved at 268, 258, and 248 K, respectively. This study revealed the general trends of the frozen decay process of bivalve species, which is instructive to establish applicative models for the real distribution chain.

Dose-response assessment for impaired memory from chronic exposure to domoic acid among native American consumers of razor clams

Domoic acid (DA) is a marine neurotoxin that accumulates in filtering shellfish during harmful algal blooms. A health protection limit of 20 ppm DA in razor clams (RC) has been set based principally upon an episode of acute DA toxicity in humans that included Amnesic Shellfish Poisoning among survivors. The objective of this study was to determine the dose-response relationship between estimated DA exposure through RC consumption and memory loss in Washington state Native Americans from 2005 to 2015. Results from total learning recall (TLR) memory scores were compared before and after the highest DA exposures. A decrease in TLR was related to DA dose (p < 0.01) regardless whether the effect was assumed to be transient or lasting, and whether the dose was expressed as an average daily dose or an average dose per meal. Benchmark dose modeling identified BMDL10 values of 167 ng/kg-day and 2740 ng/kg-meal assuming a transient effect, and 196 ng/kg-day and 2980 ng/kg-meal assuming no recovery of function occurs. These DA dose thresholds for a measurable memory function reduction observed in this study of clam consumers are well below the safe acute dose underpinning the current regulatory DA limit of 20 ppm (ca. 60 μg/kg).

The Enzyme Free Uric Acid Sensor Based on Iron Doped CuO Nanostructures for the Determination of Uric Acid from Commercial Seafood

In this study, a wet chemical method was used to produce iron-doped CuO nanostructures. Cyclic voltammetry was employed to record sensor signals in a saline phosphate buffer solution of pH 7.3. Iron added into CuO nanostructures contributed electrons to the conduction band of CuO, showing a well-resolved electro-oxidation peak for uric acid. The developed sensor exhibits a wide linear range of uric acid concentrations from 0.05 mM to 4 mM. The limit of detection for the sensor was found to be 0.01 mM. The sensor is highly selective, sensitive, and stable. The results of the in vitro analysis of uric acid motivated the researchers to measure the uric acid from the marine shellfish Perna viridis and razor clam Solen dactylus. The obtained results reveal that the proposed sensor will help to avoid the gout and could be used as an early safeguard of human health.

Quantitative and comparative study of plasmalogen molecular species in six edible shellfishes by hydrophilic interaction chromatography mass spectrometry

Shellfishes contain plasmalogens correlating to the functions of brain, heart, etc. Herein, a mild acid hydrolysis and hydrophilic interaction chromatography (HILIC) tandem mass spectrometry method was developed for analyzing plasmalogens in six shellfish species. A total of 19 plasmalogen molecular species were successfully identified, including nine phosphatidylcholine plasmalogen (plasPC), seven phosphatidylethanolamine plasmalogen (plasPE), and three phosphatidylserine plasmalogen (plasPS). The quantitative results indicated that mussel (32 μg·mg−1) possessed the highest content of plasmalogens, followed by oyster (21 μg·mg−1) and razor clam (15 μg·mg−1). The statistic models showed that the plasPE P-18:0/20:5 (m/z 748), plasPE P-16:0/22:2 & P-18:0/20:2 (m/z 754) and plasPS were the most contributing difference between shellfishes. The results indicated that this method was sensitive and precise to determine plasmalogens in shellfish, and mussel was demonstrated to be a good choice for the large-scale preparation of plasmalogens.

SBOR: a minimalistic soft self-burrowing-out robot inspired by razor clams

We observe that the Atlantic razor clam (Ensis directus) burrows out of sand rapidly by simply extending and contracting its muscular foot. This is notably different from its well-known downward burrowing strategy or the dual-anchor mechanism, where closing/opening of the shell and dilation of the foot are also involved. Inspired by this burrowing-out strategy, we design a simple self-burrowing-out robot (SBOR) consisting of a single segment of fiber-reinforced silicone tube actuator and an external control board. The reinforcing fibers limit the motion of the actuator to axial extension/contraction under inflation/deflation. For an actuator that is vertically buried in the sand, cyclic inflation and deflation naturally drives it out of the sand, mimicking the motion of a razor clam. We characterize the burrowing-out behavior of the actuator by varying the actuation period and the relative density (packing) of the sand. Each burrowing cycle features an initial upward advancement during inflation, followed by a downward slip during deflation, resulting in a net upward stride. During the burrowing-out process, the stride length first increases due to a drop in the overburden pressure, the end pull-out resistance, and the side frictional resistance; the stride length then decreases after the top of the actuator moves out of the sand layer, due to a reduction in the effective length of the actuator. The results also indicate that the average burrowing-out speed decreases with the relative density of the sand and changes with the actuation pressure. We developed a simplified model based on soil mechanics to predict the burrowing-out processes in relatively loose dry sands, and the modeling results match well with the experiment results. From this model, the burrowing-out behavior is readily explained by the asymmetric nature of the resistant forces on the two ends of the actuator and the flowing nature of sand upon yielding. Our findings imply that razor clams leverage the natural stress gradient of sand deposits to burrow upward. Another insight is that in order to burrow downward into the sand, additional symmetry-breaking features such as asymmetric geometry, friction, stress state or external load are needed to increase the resistant force (anchorage) in the upward direction and to reduce the resistant force (drag) in the downward direction.

First detection of pectenotoxin-2 in shellfish associated with an intense spring bloom of Dinophysis acuminata on the central Chilean coast

Diarrhetic shellfish poisoning (DSP) toxins and pectenotoxins (PTX) produced by endemic species of the genus Dinophysis, mainly D. acuta and D. acuminata, pose a big threat to public health, artisanal fisheries and the aquaculture industry in Southern Chile. This work reports the first detection of lipophilic toxins, including pectenotoxin-2 (PTX-2) and gymnodimine-A (GYM-A), in hard razor clam (Tagelus dombeii) associated with an unprecedented spring bloom −38.4 × 103 cells L−1 in integrated hose sampler (0–10 m) – of Dinophysis acuminata in coastal waters of central Chile. The socio-economic challenges to small-scale fisheries are discussed. The study points to the pressing need for sound policies to face unexpected HAB event, probably due to biogeographical expansions, with a focus on fisheries management, participation of stakeholders, and development of adaptive capacities.

Achieving sustainable exploitation through co-management in three Chilean small-scale fisheries

Small-scale fisheries account for most of the worldwide landings and employment. However, they are difficult to manage scientifically because the program of research and management applied to the relatively few large-scale fisheries is too onerous to be expanded to the myriad small-scale fisheries. Does this mean that SSF have a higher risk of overfishing so it would be necessary to implement more aggressively conservative measures to preemptively avoid collapse? Implementation of a stock assessment methodology developed for data-poor fisheries reveals that this may not be the case. We show that in the absence of formal stock assessment and enforcement of catch limits, Chilean small-scale fishers first apply excessive exploitation causing depletion then they eventually re-build their stocks supported by a process of co-management. We analyze three small-scale fisheries in central-south Chile: the striped clam Ameghinomya antiqua fishery in the Bay of Ancud, the razor clam Ensis macha fishery in the Gulf of Arauco, and the red octopus Enteroctopus megalocyathus fishery in the inner sea of Chiloé. We find that in the oldest fishery, for the striped clam, fishers are slowly re-building the stock from a very depressed condition, in the younger fishery for the razor clam they are recovering the stock and are close to re-building to the BMSY, and in the youngest fishery, for the red octopus, they have just shrank biomass to below BMSY. We observe that the best managed case, the fishery for the razor clam, is connected to a more mature co-management process, with fishers collaborating with government through committees of participatory management, which have provided a framework to co-manage for sustainability.

Transcriptional regulation mechanism of sterol regulatory element binding proteins on Δ6 fatty acyl desaturase in razor clam Sinonovacula constricta.

The razor clam, Sinonovacula constricta, contains high levels of long-chain PUFA (LC-PUFA), which are critical for human health. In addition, S. constricta is the first marine mollusc demonstrated to possess Δ6 fatty acyl desaturase (Fad) and complete LC-PUFA biosynthetic ability, providing a good representative to investigate the molecular mechanism of sterol regulatory element binding proteins (SREBP) in regulating Δ6 Fad for LC-PUFA biosynthesis in marine molluscs. Herein, S. constricta SREBP and Δ6 Fad promoter were cloned and characterised. Subsequently, dual luciferase and electrophoretic mobility shift assays were conducted to explore the SREBP binding elements in the core regulatory region of S. constricta Δ6 Fad promoter. Results showed that S. constricta SREBP had a very conservative basic helix-loop-helix-leucine zipper motif, while S. constricta Δ6 Fad promoter exhibited very poor identity with teleost Fads2 promoters, indicating their differentiation during evolution. A 454 bp region harbouring a core sequence in S. constricta Δ6 Fad promoter was predicted to be essential for the transcriptional activation by SREBP. This was the first report on the regulatory mechanism of LC-PUFA biosynthesis in marine molluscs, which would facilitate optimising the LC-PUFA biosynthetic pathway of bivalves in further studies.