Sea Cucumber Research Articles

Bioprospecting of sea cucumber (Holothuria sp.) as industries and functional foods for human health

Sea cucumber inhabit scattered throughout the world's in tropical, subtropical and cool waters and known high protein of marine species and bioactive compounds as well as essential and non-essential amino acids that very important for the human health. Even sea cucumbers as a potential food source have become raw materials for the health pharmaceutical industries and as a source of food that is expensive. The bioactive compounds of sea cucumbers as amino acid namely steroids, saponins, aspartic acid, glutamic acid, serine, glycine, histidine, arginine, threonine, alanine, proline, thyrosine, valine, methioni, systein, isoleucine, leucine, phenylalanine, lysine, linoleic-, oleic, omega-3, O-6, O-9, EPA and DHA. These complex bioactive compounds is beneficial for heart and blood vessel health, anticoagulant, plays an active role in curing osteoarthritis, antioxidant, antiinflammatory, antitumor, antihypertensive, anticancer, antifungal, as well as cytotoxic activity. Some research to investigate the benefits of sea cucumber bioactive compounds has created business opportunities that are processed from raw materials of fresh, frozen and dried sea cucumbers. The market products are snack packaging such as sea cucumber crackers, sea cucumber tea, sea cucumber sardines, ready-to-eat frozen sea cucumber. Sea cucumber derivative products for health have produced as supplement, capsules and skincare products in a variety of serum products, creams, body lotions, shampoos and soaps. Bioprospection of sea cucumbers which are very rich in nutrients that are important for human health as a supplement to maintain health, sufferers and the healing stage, also really supports the growth stages of children and overcomes aging.

Beronok (Meranti sea cucumber), a Meranti ethnic food culture in Indonesia

Meranti, whose capital is Selatpanjang, is one of the island areas surrounded by large rivers and is directly adjacent to the sea, which means the water is salty. Meranti is designated as a national food security development area because it generates biological wealth in western Indonesia, where beronok (meranti sea cucumber) is commonly served as a side dish to various dishes. This article investigated Indonesia's meranti ethnic food culture, specifically beronok, typically consumed raw or processed. Data of this research are about beronok as a tradisional food processed by the Meranti community made into a variety of food such as mpek-mpek, nuggets, meatbals, sausages and soups by using some steps of cooking and seasonings. The results of this investigation show that Beronok is one of the seafood and traditional food products that have the potential to generate additional valuable resources and generate a sustainable income for the community. Beronok is typically consumed raw, but is generally processed into wet foods such as 'mpek-mpek', 'nugget', 'bakso', 'sosis' and 'sup' or dried processed foods to be reused as flour. The research also showed that the Meranti people maintained their traditional food culture called “beronok” from the past to the present by utilizing their surrounding natural resources.

New Rare Triterpene Glycosides from Pacific Sun Star, Solaster pacificus, and Their Anticancer Activity.

Six previously unknown triterpene glycosides, pacificusosides L-Q (1-6), and two previously known triterpene glycosides, cucumariosides B1 (7) and A5 (8), were isolated from an alcoholic extract of Pacific sun star, Solaster pacificus. The structures of 1-6 were determined using 1D and 2D NMR, ESIMS, and chemical modifications. Compound 1 is a rare type of triterpene glycoside with non-holostane aglycon, having a linear trisaccharide carbohydrate chain. Pacificusosides M-P (2-5) have new structures containing a Δ8(9)-3,16,18-trihydroxy tetracyclic triterpene moiety. This tetracyclic fragment in sea star or sea cucumber triterpene glycosides was described for the first time. All the compounds under study exhibit low or moderate cytotoxic activity against colorectal carcinoma HCT 116 cells, and breast cancer MDA-MB-231 cells were assessed by MTS assay. Compound 2 effectively suppresses the colony formation of cancer cells at a non-toxic concentration, using the soft-agar assay. A scratch assay has shown a significant anti-invasive potential of compound 2 against HCT 116 cells, but not against MDA-MB-231 cells.

A signal recognition particle receptor gene from the sea cucumber, Apostichopus japonicas

The signal recognition particle (SRP) system delivers approximately 30% of the proteome to the endoplasmic reticulum (ER) membrane. SRP receptor alpha (SRα) binds to SRP for targeting nascent secreted proteins to the ER membrane in eukaryotic cells. In this study, the SRα homologous gene was identified in the sea cucumber, Apostichopus japonicus (AjSRα). AjSRα codes for 641 amino acids and has 54.94% identity with its mammalian homologs. Like mammalian SRα, it is expected to contain the SRP-alpha N domain, SRP54_N domain, and SRP54 domain. In addition, AjSRα is ubiquitously expressed in adult tissues and exhibits a sexually dimorphic expression pattern, with significantly higher expression in ovaries compared to testes. As a maternal factor, AjSRα can be continuously detected during embryonic development. Importantly, we first attempted to investigate its function by using lentiviral vectors for delivering SRα gene-specific shRNA, and we revealed that lentiviral vectors do not induce an upregulation of immune-related enzymes in sea cucumbers. However, compared to the dsRNA-based RNA interference (RNAi) method, lentivirus-mediated RNAi caused dynamic changes in gene expression at a later time. This study supplied the technical support for studying the functional mechanism of SRα in sea cucumbers.

Cloning and characterization of an aerolysin gene from a marine pathogen Vibrio splendidus

Vibrio splendidus is one of the main pathogens caused diseases with a diversity of marine cultured animals, especially the skin ulcer syndrome in Apostichopus japonicus. However, limited virulence factors have been identified in V. splendidus. In this study, one aerAVs gene coding an aerolysin of V. splendidus was cloned and conditionally expressed in Escherichia coli. The haemolytic activity of the recombinant AerAVs was analyzed. Western blotting was used to study of the secretion pathway of proaerolysin, and it showed that the proaerolysin was secreted via both outer membrane vehicles and classical secretion pathways. Since no active protein of aerolysin was obtained, one aerolysin surface displayed bacterium DH5α/pAT-aerA was constructed, and its haemolytic activity and virulence were determined. The results showed that the AerAVs displayed on the surface showed obvious haemolytic activity and cytotoxic to the coelomocyte of A. japonicus. Artificial immerse infection separately using the DH5α/pAT or DH5α/pAT-aerA was conducted. The result showed that the mortality percent of sea cucumber A. japonicus challenged with DH5α/pAT-aerA was 38.89 % higher than that challenged with the control strain DH5α/pAT, and earlier death occurred. Combined all the results indicates that aerolysin with the haemolytic activity and cytotoxic activity is a virulence factor of V. splendidus.

Ascorbic acid alleviates the autolysis of the sea cucumber Apostichopus japonicus via the activation of antioxidant enzymes to remove reactive oxygen species during live storage

Ascorbic acid alleviates the autolysis of the sea cucumber Apostichopus japonicus via the activation of antioxidant enzymes to remove reactive oxygen species during live storage

Dietary effect of different fermented feed sources on growth performance of early juvenile sea cucumber Holothuria scabra

The development of effective, economically viable and locally sourced diets for high-value early juvenile sea cucumber, Holothuria scabra, is important to ensure efficient juvenile production for sustainable farming and ranching. The current study applies seven fermented algal/plant diet formulations (C (control), diet seagrass Enhalus acoroides; DH, diet macroalgae Halimeda discoidea, DU, diet macroalgae Ulva lactuca, DP, diet macroalgae Padina australis, DS, diet macroalgae Sargassum polycystum, DA, diet green pond algae; DM, diet pond moss) in controlled feeding experiments for post-metamorphic juvenile H. scabra. The highest overall mean ( ± SE) individual growth rate of 0.09 ± 0.023 g d−1 was recorded for the diet green pond algae (DA), however, this diet also exhibited the lowest individual survival rate across all treatments. Combined acceptable growth rates of 0.03 ± 0.001 and 0.03 ± 0.002 g d−1, and much higher survival rates of 80.63 ± 4.38 and 80.63 ± 2.77%, respectively were recorded for diets E. acoroides (C), and Padina sp. (DP). The reasons for significant variations and survival rates are not known, however, these results indicate that the diets with acceptable survival rates may be better suited for very early juvenile sea cucumbers. Those diets exhibiting highest overall individual growth rate in the long-term may be better applied to juveniles of larger sizes later in the nursery production process. Overall results indicate good acceptance of most macroalgae fermented diets by juvenile H. scabra. Results also indicate that piloting diets at larger scales and at a variety of sizes and ages will allow determination of optimal feeding throughout the nursery production process.

Secondary Metabolites Production of Bacillus spp. Isolated from Sea Cucumbers (Holothuria scabra) and their Activity against Mycobacterium smegmatis

New anti-tuberculosis agents are very important due to Multidrug-Resistant and Extensively Drug-Resistant Tuberculosis problems. Mycobacterium smegmatis can be used to replace Mycobacterium tuberculosis as bacteria test to increase the velocity of anti-tuberculosis screening. To answer the need for new drugs, exploration of secondary metabolites from Bacillus spp. can be conducted. Bacillus spp. are known to produce antimicrobials, including discovery of iturins, fengycins, and pumilacidins. This study explored the Bacillus spp. isolated from fermented intestines of Holothuria scabra. The production of Bacillus sp. Holothuria scabra Fermented Intestine (HSFI) secondary metabolites was done using culture media containing starch as a carbon source, as well as yeast and peptone as a nitrogen source. Production capacity of secondary metabolites of Bacillus sp. HSFI was calculated, to determine its potential as an antibacterial producer. Inhibition testing of secondary metabolites of Bacillus sp. HSFI against M. smegmatis was performed using the Kirby-Bauer disk diffusion method. Based on the results of the inhibition test, it was concluded that Bacillus sp. HSFI-9 has the greatest potential to inhibit the growth of M. smegmatis, with a moderate inhibition (7.67 mm). Production of secondary metabolites from Bacillus sp. HSFI-9 is exceptionally good with an extract production capacity of 24.6 mg/L.

How Biological Activity in Sea Cucumbers Changes as a Function of Species and Tissue.

Biological activity and bioactive compound content in sea cucumbers was assessed, considering Parastichopus regalis, Holothuria mammata, Holothuria forskali, and Holothuria arguinensis as species and intestine, muscle band, respiratory tree, body wall, and gonads as tissues. P. regalis had the lowest content in phenolic compounds and antioxidant activity in contrast to Holothuria species. In the respiratory tree, the highest phenolic concentration was recorded in H. arguinensis, 76.4 ± 1.2 mg GAE/100 g dw vs. 21.0-49.0 mg GAE/100 g dw in the other species. H. arguinensis had the highest DPPH and FRAP results in the gonads, 13.6 ± 0.7 mg AAE/100 g dw vs. 2.6-3.5 mg AAE/100 g dw and 27.1 ± 0.3 μmol Fe2+/g dw vs. 8.0-15.9 μmol Fe2+/g dw, respectively. Overall, P. regalis biomass presented the highest anti-inflammatory activity levels and H. arguinensis the lowest anti-inflammatory levels. The respiratory tree was the most anti-inflammatory (measured by the inhibition of cyclooxygenase-2, COX-2) tissue in H. mammata and H. forskali (also the muscle band in this case), 76.3 ± 6.3% and 59.5 ± 3.6% COX-2 inhibition in 1 mg/mL aqueous extracts, respectively. The results demonstrated a variable bioactive potential and advantage in targeting antioxidant properties in the muscle band and anti-inflammatory activity in the respiratory tree, which may constitute a starting point for a biorefinery approach envisaging multiple applications.

Segment Anything Model (SAM) Assisted Remote Sensing Supervision for Mariculture—Using Liaoning Province, China as an Example

Obtaining spatial distribution information on mariculture in a low-cost, fast, and efficient manner is crucial for the sustainable development and regulatory planning of coastal zones and mariculture industries. This study, based on the Segment Anything Model (SAM) and high-resolution remote sensing imagery, rapidly extracted mariculture areas in Liaoning Province, a typical northern province in China with significant mariculture activity. Additionally, it explored the actual marine ownership data to investigate the marine use status of Liaoning Province’s mariculture. The total area of mariculture we extracted in Liaoning Province is 1052.89 km2. Among this, the area of cage mariculture is 27.1 km2, while raft mariculture covers 1025.79 km2. Through field investigations, it was determined that in the western part of Liaodong Bay, cage mariculture predominantly involves sea cucumbers. In the southern end of Dalian, the raft mariculture focuses on cultivating kelp. On the other hand, around the islands in the eastern region, the primary crop in raft mariculture is scallops, showing a significant geographical differentiation pattern. In the planned mariculture areas within Liaoning Province’s waters, the proportion of actual development and utilization is 11.2%, while the proportion approved for actual mariculture is 90.2%. This indicates a suspicion that 9.8% of mariculture is possibly in violation of sea occupation rights, which could be due to the untimely updating of marine ownership data. Based on SAM, efficient and accurate extraction of cage mariculture can be achieved. However, the extraction performance for raft mariculture is challenging and remains unsatisfactory. Manual interpretation is still required for satisfactory results in this context.

Potential Development of Sea Cucumber Farming in Tablolong Beach, Kupang, East Nusa Tenggara

Tablolong Beach, Kupang, West Nusa Tenggara, has significant potential for sea cucumber aquaculture development. This study examines the environmental conditions, climatic factors, and local natural resources that support sea cucumber farming in this area. The results showed that Tablolong Beach has very suitable environmental characteristics for sea cucumber growth, including suitable water temperature and sufficient natural food availability. In addition, the local community has strong traditional knowledge on sea cucumber collection and cultivation. the purpose of this study was to determine the potential and types of sea cucumbers found around Tablolong beach. This research method is an experimental method where samples are taken by diving in the waters of Tablolong beach. Sea cucumber species found consisted of H. atra, H. leucospilota, H. fuscocinerea, and S. monoturbeculatus. This research provides an important basis for designing a sustainable sea cucumber aquaculture development plan in Tablolong Beach, integrating ecological, economic, and social aspects. By utilizing the natural potential and local knowledge, the development of sea cucumber aquaculture in this area can become a model for sustainable utilization of marine resources and support the livelihoods of coastal communities

Seasonal and taxa impact on edible sea cucumber metabolome as analyzed via a multiplex approach of mass spectroscopy-based metabolomics

Sea cucumbers, belonging to class Holothuroidea, are marine invertebrates with substantial bioactive compounds and nutritive value. This study presents a multiplex metabolomics approach to dissect between winter and summer samples of two Red Sea cucumbers: Holothuria atra and Actinopyga crassa. LC-MS and GC-MS followed by multivariate data analyses were employed for metabolites profiling and seasonal biomarkers assignment for each species. A total of 314 metabolites were annotated in both species belonging to amino acids, sugars, sugar alcohols, acids, triacylglycerides (TAGs), phospholipids, lyso-phospholipids, sphingolipids, phosphatidylcholines, diacylglycerols, different glycolipids, and others, adding to the nutritive value of sea cucumber. GC-MS analysis revealed for amino acids i.e., alanine as the main polar primary metabolite class in sea cucumbers. LC-MS analysis targeting non-polar metabolites revealed TAGs as the main class followed by phospholipids and lyso-phospholipids. Multivariate orthogonal partial least square discriminant analysis (OPLS-DA) revealed that A. crassa is enriched in alanine and lactic acid than H. atra versus higher levels of pyroglutamic acid and ethanolamine and TAGs in the later. Summer A. crassa was distinguished from its winter specimen by its higher TAGs, glycine and glycerol levels versus enrichment of winter samples in lyso-phospholipids, isoleucine, and proline. Such metabolomic study revealed for A. crassa and H. atra richness in nutrient metabolites, alongside collection season effect on their amino acids and lipids profiles.

Diversitas and Distribution Pattern of Sea Cucumbers in Bajo Village Boalemo Sub District Tomini Bay Gorontalo

This research aims to determine the types, characteristics, diversity and distribution patterns of sea cucumbers in Bajo Village, Tilamuta District, Boalemo Regency. This research was conducted for 3 months starting from August to October 2022. Data collection on sea cucumber was carried out at 3 stations with 3 quadrants at each station with a quadrant size 4×25 meters, samples were taken at low tide during the day and at night. In addition, measurements of the physical and chemical quality parameters of the waters were also carried out. Based on the results of the study, 9 species pf sea cucumbers were found in Bajo Village, Tilamuta Sub District: Holothuria scabra, Holothuria atra, Holothuria coluber, Holothuria fuscocinerea, Stichopus vastus/gammat, Holothuria hilla, Actinopyga miliaris, Bohadchia similis, and Synapta maculata. Moreover, the abundance of sea cucumbers in the waters of Bajo Village, Tilamuta Sub District, Boalemo Regency, was found during daytime sampling. The diversity of sea cucumbers in the waters of Bajo Village ranges from 1,59–1,89 which is included in the medium category according to the Shannon-Wiener. In short, the distribution pattern of sea cucumbers in the waters of Bajo Village is more dominant in living in groups.

Enzyme-Assisted Extraction of Fucosylated Chondroitin Sulfate from Sea Cucumber Holothuria scabra and Bohadschia argus and their Potential in Pharmaceutical Applications

Due to the health benefit of fucosylated chondroitin sulfate (FuCS), the efficient method for extraction of FuCS from raw materials is a crucial issue in reducing the production cost. In this study, enzymatic extraction of FuCS from two species of sea cucumber, Holothuria scabra and Bohadschia argus was undertaken using two protease enzymes, alcalase and papain. Response surface methodology (RSM) was employed in determining the optimal extraction conditions with the highest yield of FuCS concentration. The predicted optimal papain-assisted extraction conditions of Holothuria scabra and Bohadschia argus obtained a predicted FuCS yield of 1609.73 mg/100 g and 444.51 mg/100 g, respectively. To compare extraction efficiencies of two protease enzymes, employment of the RSM optimal conditions to Holothuria scabra resulted in 1538.76 ± 20.26 mg/ 100 g and 1295.50 ± 14.28 mg/100 g of purified FuCS for papain and alcalase, respectively. Whereas Bohadschia argus produced 412.39 ± 10.12 mg/100 g and 461.11 ± 8.45 mg/100 g purified FuCS for papain and alcalase, respectively. The acquired FTIR and NMR spectrums of extracted FuCS showed typical bands of sulfation patterns and were compared to commercial FuCS. The extracted FuCS showed enzyme type dependent antioxidant activity, and significant tyrosinase inhibitory activity than commercial FuCS. It also exhibited similar anti-glucosidase activity as commercial FuCS. Thus, this study reveals potential applications of enzyme-assisted FuCS from sea cucumber in food and pharmaceutical industries.

Preparation of Novel Sea Cucumber Intestinal Peptides to Promote Tibial Fracture Healing in Mice by Inducing Differentiation of Hypertrophic Chondrocytes to the Osteoblast Lineage.

Hypertrophic chondrocytes have a decisive regulatory role in the process of fracture healing, and the fate of hypertrophic chondrocytes is not only apoptosis. However, the mechanism of sea cucumber (Stichopus japonicus) intestinal peptide (SCIP) on fracture promotion is still unclear. This study aims to investigate the effect of sea cucumber intestinal peptide on the differentiation fate of hypertrophic chondrocytes in a mouse tibial fracture model. Mice are subjected to open fractures of the right tibia to establish a tibial fracture model. The results exhibit that the SCIP intervention significantly promotes the mineralization of cartilage callus, decreases the expression of the hypertrophic chondrocyte marker Col X, and increases the expression of the osteoblast marker Col I. Mechanically, SCIP promotes tibial fracture healing by promoting histone acetylation and inhibiting histone methylation, thereby upregulating pluripotent transcription factors induced the differentiation of hypertrophic chondrocytes to the osteoblast lineage in a manner distinct from classical endochondral ossification. This study is the first to report that SCIP can promote tibial fracture healing in mice by inducing the differentiation of hypertrophic chondrocytes to the osteoblast lineage. SCIP may be considered raw material for developing nutraceuticals to promote fracture healing.

Study on the differences in flavor adsorption ability of sea cucumber each part based on HS-SPME-GC-MS

Flavor modification of ready-to-eat sea cucumbers during the seasoning process has received increasing attention. Currently, limited research has been conducted regarding the variances in flavor adsorption ability among different parts of sea cucumber. In this study, water was used as a medium to synergistically convey the Chinese prickly ash characteristic volatiles to migrate into sea cucumber for the preparation of seasoned sea cucumber. The types and concentrations of the characteristic volatiles in the skin layer, muscle layer and tendon layer of the sea cucumbers under the optimal soaking conditions were analyzed based on headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS). The key active volatiles in each sea cucumber sample include: 2-nonanol, myrcene, beta-phellandrene, terpinen-4-ol, alpha-terpineol, piperitone, cineole, and linalool. The results of heat map and partial least squares discriminant analysis (PLS-DA) indicate that the skin layer of sea cucumber demonstrated the strongest adsorption ability to the characteristic volatiles, while the tendon layer showed the weakest adsorption ability. There was a significant difference in the flavor profiles between control sea cucumber and seasoned sea cucumber. (Z)-3-decen-1-ol, 2,4-dimethyl styrene, linalool, d-limonene, and cineole were the key difference volatiles among the seasoned sea cucumber parts. This study through studying the differences in the ability of different parts of sea cucumber in adsorption Chinese prickly ash characteristic volatiles can better explore the gastronomic value of ready-to-eat sea cucumber, leading to the development of a wider range of sea cucumber delicacies, and offer valuable references in fields like sea cucumber processing and product development.

Sex differences in the growth of sea cucumber (Apostichopus japonicus)

Sea cucumber (Apostichopus japonicus) is a commercially important mariculture species in China. Generally, sea cucumbers weighing around 100 g and older than two years, with mature gonads are harvested for food. Sexual dimorphism is widely observed in aquaculture animals, and sex control biotechnologies have created typical cases of genetic breeding in several aquaculture species. Clarifying the sex differences in important economic traits and developing a rapid genetic sex identification method are critical steps for establishing a monosex aquaculture population. In the present study, we established a loop-mediated isothermal amplification (LAMP) based method to identify the genetic sex of sea cucumbers in the field without complex equipment. Subsequently, we investigated the growth difference between males and females in terms of weight gain, and revealed that there was no significant growth difference between males and females 1–2-year-old juvenile sea cucumbers with undifferentiated gonads. However, among 2–3-year-old adult sea cucumbers with differentiated gonads, males exhibited greater growth advantages compared to females. The weight increment and specific growth rate (SGR) of male sea cucumbers were 1.73 and 1.52 times greater than those of female sea cucumbers, respectively, highlighting the economic value in producing all-male populations of A. japonicus. Furthermore, the expression levels of growth trait candidate genes (hgfr1 and c-myc) in the body wall tissues showed no significant differences between males and females of 1–2-year-old A. japonicus. However, in 2–3-year-old A. japonicus, the expression levels of these genes were significantly higher in males than in females. Conversely, cyp1a1 and cyp17a genes were more highly expressed in differentiated ovaries than in differentiated testes. This study provides a solid foundation for achieving sex control breeding in sea cucumbers.

Interaction between a Sulfated Polysaccharide from Sea Cucumber and Gut Microbiota Influences the Fat Metabolism in Rats.

Due to its significant physiological effects, a sulfated polysaccharide has been considered an important nutrient of sea cucumber, but its metabolism in vivo is still unclear. The present study investigated the metabolism of a sea cucumber sulfated polysaccharide (SCSP) in rats and its influence on the metabolite profiles. The quantification by HPLC-MS/MS revealed that the blood level of SCSP achieved a maximum of 54.0 ± 4.8 μg/mL at 2 h after gavage, almost no SCSP was excreted through urine, and 55.4 ± 29.8% of SCSP was eliminated through feces within 24 h. These results prove the utilization of SCSP by gut microbiota, and a further microbiota sequencing analysis indicated that the SCSP utilization in the gut was positively correlated with Muribaculaceae and Clostridia_UCG-014. In addition, the non-targeted metabolomic analysis demonstrated the significant effects of SCSP administration on the metabolite profiles of blood, urine, and feces. It is worth noting that the SCSP supplement decreased palmitic acid, stearic acid, and oleic acid in blood and urine while increasing stearic acid, linoleic acid, and γ-linolenic acid in feces, suggesting the inhibition of fat absorption and the enhancement of fat excretion by SCSP, respectively. The present study shed light on the metabolism in vivo and the influence on the fat metabolism of SCSP.

Combined application of nitrogen, phosphorus, iron, and silicon improves growth and fatty acid composition in marine epiphytic diatoms

IntroductionMarine epiphytic diatoms are natural diets for multiple marine invertebrates, including sea cucumbers, sea urchins, etc. They also act as bioindicators in marine waters to assess water quality of coastal ecosystems. Material and methodsWe isolated three strains of Navicula and two strains of Nitzschia from macroalgal epiphytes. Combined concentrations of four macroelements, five trace metals, and three vitamins in f/2 medium were optimized for these diatoms using single-factor and orthogonal tests. Results and discussionThe biomass productivities for 4-L enlarged cultures of the five isolated diatoms in their exclusively optimized f/2 media all increased by nearly 10-fold relative to f/2 medium, and that of Navicula-1 and Nitzschia-2 reached the highest, i.e., 29.52 ± 1.98 and 30.68 ± 2.84 g m-2 d-1, respectively. Moreover, the relative abundance of C20:5n3 in the exclusively optimized f/2 medium-cultured Navicula-1 notably rose by 24%, and that in Nitzschia-2 held stable at > 25%. Thus, Navicula-1 and Nitzschia-2 were screened out with outstanding growth traits and improved fatty acid compositions at high levels of combined nitrogen, phosphorus, iron, and silicon. The two diatoms have potential for becoming quality diets for marine aquaculture, and ideal candidates for effective nutrient removal.

Transcriptomic Responses of a Lightly Calcified Echinoderm to Experimental Seawater Acidification and Warming during Early Development.

Ocean acidification (OA) and ocean warming (OW) are potential obstacles to the survival and growth of marine organisms, particularly those that rely on calcification. This study investigated the single and joint effects of OA and OW on sea cucumber Apostichopus japonicus larvae raised under combinations of two temperatures (19 °C or 22 °C) and two pCO2 levels (400 or 1000 μatm) that reflect the current and end-of-21st-century projected ocean scenarios. The investigation focused on assessing larval development and identifying differences in gene expression patterns at four crucial embryo-larval stages (blastula, gastrula, auricularia, and doliolaria) of sea cucumbers, using RNA-seq. Results showed the detrimental effect of OA on the early development and body growth of A. japonicus larvae and a reduction in the expression of genes associated with biomineralization, skeletogenesis, and ion homeostasis. This effect was particularly pronounced during the doliolaria stage, indicating the presence of bottlenecks in larval development at this transition phase between the larval and megalopa stages in response to OA. OW accelerated the larval development across four stages of A. japonicus, especially at the blastula and doliolaria stages, but resulted in a widespread upregulation of genes related to heat shock proteins, antioxidant defense, and immune response. Significantly, the negative effects of elevated pCO2 on the developmental process of larvae appeared to be mitigated when accompanied by increased temperatures at the expense of reduced immune resilience and increased system fragility. These findings suggest that alterations in gene expression within the larvae of A. japonicus provide a mechanism to adapt to stressors arising from a rapidly changing oceanic environment.