No. 0 diesel oil may pose a serious threat to sea cucumber (Apostichopus japonicus) aquaculture by inducing skin ulceration. This study aimed to evaluate the protective efficacy and mechanism of a previously developed inhibitor composition against diesel-induced injury. The inhibitor composition significantly alleviated skin ulceration in the experimental group (Eg), reducing the lesion area to 14.44 ± 1.79% after 96 h, compared to 33.19 ± 2.94% in the diesel-exposed control group (Cg) (p < 0.05). It effectively suppressed the overactivation of autolytic enzymes (cathepsin L and B) while enhancing the activities of acetylcholinesterase, superoxide dismutase, and catalase. Transcriptomic profiling revealed 3137 differentially expressed genes, with functional enrichment in pathways related to Notch signaling, ECM-receptor interaction, glycosaminoglycan biosynthesis, and detoxification. The upregulation of genes such as HES-C, CYP1A1, GST, and UGT may be linked to the regulation of apoptosis inhibition, xenobiotic metabolism, and antioxidant defense. Furthermore, enhanced expression of NAD kinase and PNLIPRP may indicate a potential strengthening of energy metabolism and lipid utilization during stress adaptation. This study suggests that the inhibitor composition may exert a multi-level protective effect against diesel-induced injury by coordinating tissue repair, oxidative balance, and detoxification processes, offering a potential strategy to mitigate pollution impacts in sea cucumber aquaculture.

To explore morphological features and molecular dynamics underlying skeletogenesis in the sea urchin Strongylocentrotus intermedius, we conducted combined morphological observation and comparative transcriptome analyses across representative embryonic and larval developmental stages. Morphological results showed that triradiate spicules first emerged at the gastrula stage. The 8-arm pluteus stage was identified as a key phase for skeletal remodeling, during which new three-radiate crystals transformed into complex stereoscopic ossicles including tube feet, spines and test plates. Transcriptomic data indicated that most differentially expressed genes (DEGs) were downregulated from the blastula to gastrula. The altered expression of basal metabolic genes and extracellular matrix genes including Colp2α and calm may be correlated with the linear mineralization of early spicules, which potentially reflects an energy adjustment pattern in developing larvae. During the transition from 6-arm to 8-arm pluteus, expression changes of calmodulin-like, Colp2α and SISin18G001660 suggest potential associations with regional calcium deposition and modifications of skeletal matrix properties. This work systematically characterizes morphological traits and transcriptional dynamics of skeletogenesis in S. intermedius. Its early spiculogenesis follows the conserved developmental pattern of echinoderms, while massive formation of stereoscopic ossicles occurs at the 8-arm pluteus stage. Stage-specific transcriptional changes across key larval skeletogenic stages are uncovered, offering transcriptomic resources for functional verification of skeletal regulatory genes.

Cisplatin (CP) chemotherapy often causes ototoxicity, a major side effect. Maslinic acid (MA), a pentacyclic triterpenoid with known anti-inflammatory and antioxidant properties, was investigated for its protection against CP-induced hearing loss. In vivo, MA maintained the hearing threshold of CP-treated mice at 50-60 dB SPL and prevented damage to the stria vascularis and spiral ganglion. Proteomic analysis indicated that MA reduces ototoxicity by inhibiting oxidative stress and ferroptosis pathways. In vitro, MA counteracted the loss of HEI-OC1 cell viability induced by CP or the ferroptosis inducer sulfasalazine (SAS), while suppressing ferroptosis markers such as lipid peroxidation, ROS, and MDA. Mechanistically, MA promoted membrane localization of SLC7A11, enhancing cysteine uptake and activity, and upregulated GPX4 expression, thereby strengthening cellular resistance to ferroptosis. These results support further development of MA as a therapeutic agent against cisplatin-induced ototoxicity.

Fructose is an abundant monosaccharide in the human diet and an important source of energy in the human body. GLUT5, a member of facilitative glucose transporter family, is the only membrane transporter that specifically transports fructose in the human body, and plays an important role in dietary fructose uptake and metabolism. Previous studies have shown that medium-chain fatty acids (MCFAs) can regulate glucose metabolism via modulating glucose transporters. However, it has not been addressed if MCFAs can regulate GLUT5-mediated fructose metabolism. In the present study, we demonstrated for the first time that MCFAs but not short chain or long chain fatty acids are able to promote fructose uptake in both IEC-18 rat intestinal epithelial cells and human MDA-MB-231 breast cancer cells (a commonly used cell line for fructose metabolism-related study) measured by 1-NBD-Fructose-based assay, which are well correlated with the activation of GLUT5-KHK axis. Moreover, the activation of GLUT5-ketohexokinase (KHK) axis was also achieved in vivo by the treatment with tricapylin, a precursor of octanoic acid (OA), leading to the improvement in fructose-based energy recovery after fasting. The findings of the present study not only provide novel mechanistic support for MCFAs as regulator of carbohydrate metabolism, but also denote that MCFAs could be useable for managing fructose-associated metabolic diseases or as an enhancer for energy recovery after fasting or exercise.

The sea cucumber (Apostichopus japonicus) is an important cultured species with high nutritional and economic value. Body surface papillae are prominent body wall structures, whose morphology can influence external appearance and commercial grading while also being capable of regeneration. Despite their importance, the cellular and molecular mechanisms underlying papilla regeneration in A. japonicus remain largely unknown. We hypothesized that this process is orchestrated by a dynamic interplay between extracellular matrix (ECM) remodeling and evolutionarily conserved signaling pathways. To test this, this study involved the excision of papillae from sea cucumbers, followed by morphological, histological and transcriptomic analyses at 1, 3-, 7-, 14, and 21-days post-experiment. Morphological analysis indicated that by 21 days post-regrowth, the appearance of the sea cucumber papillae was nearly indistinguishable from its pre-regrowth state. Histological analysis revealed that the tissues had largely reverted to their normal state by the 21st day of regeneration. Thus, the regeneration period of papillae is approximately 21 days. An Illumina transcriptome analysis was performed on the sea cucumbers at 1, 3-, 7-, 14-, and 21-days after the papillae were cut. Differentially expressed genes were classified and enriched through GO and KEGG databases. These results suggest that the regeneration of sea cucumber papillae is associated with the reconstruction of the extracellular matrix, and the ECM-receptor interaction signaling pathway plays a pivotal role in this process. Several key genes, such as COL1A2, DMBT1, fibropellin-ia, TNXB, and KCP, were identified as collective regulators of papillae regeneration in sea cucumbers. Sea cucumbers exhibit an extraordinary capacity to regenerate damaged or lost tissues and organs. This study identifies the ECM-receptor interaction pathway and key genes (such as COL1A2, DMBT1) as crucial regulators of sea cucumber papillae regeneration.

Based on the sheltering behavior, shelters are widely applied to enhance the aquaculture efficiency of sea cucumbers. However, the characteristics of sheltering behavior are still poorly understood in sea cucumbers. This study investigated the characteristics of the sheltering behavior of the sea cucumber Apostichopus japonicus under individual, group, and interspecific levels. In the individual experiment, the research findings showed that, regardless of whether it was day or night, there were no significant differences in the movement randomness, first-arrival time, and movement speed of sea cucumbers. Regardless of whether it was day or night, the residence time of sea cucumbers in the group with shelters was significantly longer than that in the group without shelters. This indicates that sea cucumbers are random into shelters rather than random leaving the shelter, no matter in the day or at night. In the group experiment and inter-species experiment, no significant differences existed in the residence time, the first-arrival time and the movement speed. This suggests that the basic characteristics of sheltering behavior of sea cucumbers is not affected by the interaction at the present densities. The present study clarified the characteristics of sheltering behavior of sea cucumbers under individual, group, and inter-species interactions. This research uncovered the characteristics of the sheltering behavior of A. japonicus and offered crucial information for enhancing the aquaculture efficiency of sea cucumbers in shelter.

18β-Glycyrrhetinic acid (GA) is a major metabolite of glycyrrhizin (GL) that is a key ingredient of licorice, a popular edible and medicinal plant, and is often used in the food and pharmaceutical industry as a flavoring agent. Previous studies suggest that licorice possess hematopoietic activity. However, the bioactive ingredients in licorice that produce hematopoietic effect remain elusive. This study aimed to test if GA is the key active molecule that contributed to the anti-anemia activity of licorice. Both in vivo and in vitro models were utilized to determine the efficacy of GA against renal anemia and to decipher its related mechanisms. We found for the first time that oral administration of GA at clinically safe doses is effective against renal anemia, illustrated by the improvement in key hematological parameters. Mechanistically, GA was found to be able to directly bind to and inhibit PHD2, analyzed by molecular docking simulation, surface plasmon resonance (SPR), cellular thermal shift assay (CETSA), and a time-resolved fluorescence resonance energy transfer (TR-FRET)-based enzyme activity assay. PHD2 inactivation by GA led to the activation of HIF-2α-erythropoietin (EPO) pathway, accompanied by improved iron availability and inhibition of inflammation. Further, the tissue distribution analysis revealed that the concentrations of GA in target organ kidney and liver are 120.39 and 83.86 μg/g respectively, exceeding IC50 of 18.83 μg/mL for inhibition of PHD2. The findings therefore identified GA as a novel HIF-PHD2 inhibitor with favorable target tissue distribution that contributed to the anti-anemia effect of licorice and warrants further investigation.

Oleanane-type pentacyclic triterpene is a major class of naturally occurring pentacyclic triterpenes with various bioactivities. A growing body of evidence suggests that glycyrrhetinic acid (GA), oleanolic acid (OA), and maslinic acid (MA), three representatives of oleanane-type pentacyclic triterpenes, are capable of regulating metabolism of carbohydrate and lipid, accordingly improving energy metabolism and alleviating metabolic disorders. A number of mechanisms have been found to contribute to the regulatory effects of GA, OA and MA on carbohydrate and lipid metabolism. These mainly include targeting transporters of glucose or fatty acids, reshaping gut microbiota, activating autophagy, inhibiting transcription factors (hepatic nuclear factor 4α, HNF4α; peroxisome proliferator-activated receptor, PPARγ; sterol regulatory element binding protein 1, SREBP-1), inactivating metabolic enzymes (α-glucosidase; 11beta-hydroxysteroid dehydrogenase type 1, 11β-HSD1), and suppressing oxidative stress. Understanding of the mechanisms involved in the regulatory effect of GA, OA and MA on carbohydrate and lipid metabolism will promote their application in improving metabolism and fighting against the dysregulated energy metabolism-related diseases. In this review, we present an overview of the current understanding of the mechanisms underlying these representative pentacyclic triterpenes-mediated metabolic regulation in both physiological and pathological conditions. We also incorporate molecular docking analyses to complement the mechanistic discussion by predicting direct interactions between GA/OA/MA and key proteins involved in glucose and lipid metabolism. Furthermore, we propose the issues that need to be further investigated for promoting clinical utilization of these compounds in the future studies.

Shelters can enhance the growth efficiency of sea cucumbers, while the preference of sea cucumbers for shelters varies among individuals. Therefore, this study investigated the behavioral and physiological requirements of the sea cucumber Apostichopus japonicus for artificial shelters. In this experiment, we considered sea cucumbers that spent more than 80% of their time (2880 s) inside the shelter as the sheltered sea cucumbers and those that spent less than 20% of their time (720 s) inside the shelter as the non-sheltered sea cucumbers. We found that mouth tentacle grasping times in the sheltered group were significantly lower than in the non-sheltered group, while foraging selections of both groups were not significantly different. This indicates that feeding is the behavioral requirement for the sheltered group instead of foraging. The height of the intestinal crease was significantly shorter in the sheltered group than in the non-sheltered group. Further, the defecation rate and 5-HT content in the intestinal tract of the non-sheltered group were significantly lower than those of the sheltered group. This indicates that the sheltered group has a greater demand for food digestion than the non-sheltered group. Compared with the non-sheltered group, the sheltered group showed higher relative abundances of Gammaproteobacteria and Bacteroidia in the gut microbiota. The thermal tolerance was significantly worse in the sheltered group. Furthermore, there was no significant difference in movement distance after mechanical disturbance between the two groups. Cortisol content showed no significant difference either. These indicate that the sheltered sea cucumbers do not require shelters for stress relief in the absence of external handling stress. This study clarified the behavioral and physiological requirements of sea cucumbers on shelters and enriched our understanding of the shelter dependence of sea cucumbers.

Tyrosinase is the rate-limiting enzyme in melanogenesis and food browning, making its inhibitors crucial for health and food preservation. However, the specific mechanisms by which multi-berry formulations synergistically inhibit tyrosinase remain uncharacterized, particularly within the context of overcoming bioactivity limitations caused by standardized food ingredients. Our study revealed that blueberry-black chokeberry extracts at 1:1 ratio with superior synergistic inhibition in tyrosinase. Using affinity-ultrafiltration coupled with ultra-performance liquid chromatography-mass spectrometry (AUF-UPLC-MS), sixteen inhibitors were identified, notably delphinidin-3-O-galactoside (IC50 = 45.06 ± 1.32 μM) and cyanidin-3-O-arabinoside (IC50 = 55.54 ± 0.83 μM) displayed the highest binding affinities with synergistic inhibition at 4:1-ratio. This anthocyanin mixture exhibited reversible mixed-type inhibition, with Lineweaver-Burk analysis and multi-spectroscopic studies confirming stable complex formation. Molecular docking and dynamics simulations revealed the mixture sequence-specific inhibition mediated by enhanced hydrogen bonding that prevented drastic structural changes. The anthocyanin mixture also exhibited enhanced processing stability. These findings provided mechanistic foundations for developing multi-berry-derived anti-tyrosinase ingredients, enabling bioactivity maximization in industrial food processing.

The aquaculture of the sea cucumber Apostichopus japonicus is threatened by high temperature-induced skin ulceration in northern China. The present study compared the behavioral and physiological responses between ulcerated and non-ulcerated sea cucumbers at 32 °C, and evaluated the anti-ulceration advantages of reef-seeking behavior. Behavioral tests revealed a significantly lower reef-seeking tendency in ulcerated individuals compared to the non-ulcerated ones (P < 0.01), whereas righting, adhesion, and feeding behaviors did not differ significantly. Further, ulcerated sea cucumbers exhibited higher cortisol levels (P = 0.036), and exogenous cortisol injection significantly increased significanfly the ulceration rate (P = 0.018). These findings indicate that skin ulceration greatly impairs reef-seeking behavior, with cortisol mediating ulceration development. Compared to non-reef-seeking individuals, reef-seeking sea cucumbers developed significantly fewer ulcers (P = 0.001) and maintained significantly lower concentrations of cortisol (P = 0.032) and serotonin (5-HT) (P = 0.036). These findings indicate reef-seeking behavior enhances the ulcer resistance by regulating cortisol and 5-HT levels. Collectively, the present study showed that reef-seeking sea cucumbers had better behavioral and physiological traits under heat stress, and were with a markedly lower skin ulceration rate than non-reef-seeking individuals.

The sea urchin Strongylocentrotus intermedius, a commercially valuable species in aquaculture, is highly susceptible to heat stress, yet the cellular heterogeneity underlying its intestinal response remains unexplored. In this study, single-cell RNA sequencing (scRNA-seq) was employed to generate an intestinal single-cell atlas of S. intermedius and to compare transcriptomic responses under normal temperature (15 °C) and heat stress (25 °C) conditions. A total of 16 cell subpopulations were identified and classified into epithelial, neural, muscle, and immune cell categories. Under heat stress, the proportions were reduced in exocrine pancreatic-like cells, immune granular cells, immune-sensing epithelial cells, and progenitor cells. Functional analyses revealed cell-type-specific disruptions: progenitor proliferation was suppressed via downregulation of cell-cycle and oxidative phosphorylation pathways, while accelerated epithelial cell death compromised intestinal barrier integrity. Digestive cell clusters exhibited coordinated suppression of nutrient absorption and energy metabolism pathways, suggesting a hypometabolic survival strategy. Enteric neural transmission was impaired through dysregulated acetylcholine metabolism and synaptic vesicle release, and innate immune defense was weakened by reduced expression of pattern recognition receptors, ROS-producing enzymes, and antimicrobial peptides.In summary, this study provides the first single-cell characterization of intestinal thermal responses in S. intermedius, demonstrating that heat stress compromises intestinal barrier integrity, induces hypometabolism, and disrupts neuroimmune coordination. From an aquaculture perspective, these findings provide a cellular-level mechanistic basis for mitigating thermal impacts in summer, thereby contributing to the reduction of heat-stress-induced mortality and production losses, and ultimately promoting the sustainable sea urchin aquaculture.

The sea urchin Strongylocentrotus intermedius is a commercially cold-water species in China, and is highly sensitive to temperature fluctuation. High temperatures from global warming pose a major threat to its survival and physiological homeostasis in summer. However, little is known about the molecular regulatory mechanisms of the heat stress response in the intestine of adult S. intermedius. In this study, RNA sequencing and data-independent acquisition (DIA)-based proteomics were applied to investigate intestinal transcriptomic and proteomic responses of adult S. intermedius following a 15 day high-temperature exposure (25 °C), compared with a control group maintained at 15 °C. Transcriptomic profiles showed that heat stress significantly suppressed the expression of COX and ATPase subunits in the oxidative phosphorylation pathway, potentially reducing energy synthesis efficiency. Meanwhile, the expression of heat shock proteins and molecular chaperones was upregulated to enhance misfolded protein repair. In the proteomic profile, high temperature upregulated LC3C and STK11 in autophagy pathway, which may promote the clearance of damaged components, while caspase-3 mediated apoptosis was also enhanced. Integrative analysis identified 20 co-upregulated DEGs/DEPs, mostly enriched in protein processing in the endoplasmic reticulum pathway, highlighting its key role in high temperature response. Additionally, cathepsins involved in immune-related pathways were downregulated, potentially affecting intestinal immunity. The present study enriches the current knowledge of the high temperature response in adult S. intermedius, and provides important insights into heat stress regulation in S. intermedius and other echinoderms.

Optimizing protein utilization is critical for the sustainable aquaculture of the sea cucumber Apostichopus japonicus, because protein represents a costly yet indispensable component of aqua-feeds. The present study compared the behavioral and physiological differences among sea cucumbers that were fed a high-protein diet and had different growth performances. Here, sea cucumbers, which were fed a high-protein diet and subsequently exhibited higher growth rates, showed significantly higher food consumption and spent significantly less time in the food zone, indicating enhanced foraging efficiency. The tentacle activity of these individuals was significantly higher than that of those with lower growth rates. Thus, sea cucumbers that were fed a high-protein diet and showed better growth performance had more efficient feeding strategies. High-growth individuals exhibited significantly lower phosphofructokinase activity. This indicates a reduced reliance on glycolysis and a greater capacity for endogenous energy production or utilization in A. japonicus. In addition, the intestinal microbiota of high-growth individuals was characterized by a higher abundance of the family Erysipelotrichaceae. Furthermore, gut mass/body mass of high-growth individuals was significantly lower than that of those with lower growth rates. This indicates that these high-growth individuals responded better to the high-protein diet. The present findings are valuable to elucidate the effects of high-protein diets on sea cucumber behavior and physiology, and to offer useful insights into sea cucumber aquaculture.

Sea cucumbers (Apostichopus japonicus) show fleeing, adhesion, and thanatosis patterns upon exposure to various stressors. However, the molecular mechanisms underlying these contrasting stress response patterns remain largely unknown. In the present study, we performed a transcriptomic analysis of coelomocytes on stressed sea cucumbers to elucidate the potential molecular mechanisms. The RNA-seq results revealed that several matrix metalloproteinase (MMP) family genes, along with HTR4, HRH2, and ADRA1D (which are involved in neuroactive ligand-receptor interactions), were significantly upregulated in the fleeing pattern. These genes may facilitate rapid movement. In the adhesion pattern, PHKA and PGK were significantly downregulated, and the differentially expressed genes (DEGs) were significantly enriched in the longevity regulating pathway, accompanied by downregulation of KRAS and HSPA1. These genes and the pathway may be involved in the reallocation of energy resources during the adhesion pattern. In the thanatosis pattern, DEGs were significantly enriched in the MAPK signaling pathway (including upregulation of ANGPT1 and FGFR1) and in the Rap1 and Ras signaling pathways (with downregulation of key genes: RAPGEF4, RRAS2, and RaLA). These genes potentially contribute to sustaining the thanatosis pattern. These transcriptomic profiles provide novel insights into the distinct molecular signatures underlying each stress response pattern in A. japonicus.

The effective development of high-salinity aquaculture for the sea urchin Strongylocentrotus intermedius depends on understanding its molecular mechanisms. Therefore, we conducted a 60-day experiment to investigate the effects of prolonged high-salinity stress on the survival, growth, amino acid levels, antioxidant enzyme activity, and gene expression of S. intermedius. The experiment involved the preparation of two groups: one with a salinity of 32 (group S32) and another with 36 (group S36). The results showed that the survival rate of S. intermedius in group S36 was 80% ± 6.7%, while the weight gain rate was only 61.58% ± 1.92%. Both parameters were significantly lower than those in group S32 (P < 0.05). In addition, the GSH, Cys, and Glu expression in S. intermedius was significantly higher than that observed in group S32 (P < 0.05). The transcriptomic results showed that, when comparing groups S32 and S36, 179 differentially expressed genes were identified. These genes were predominantly enriched in pathways related to metabolism and amino acid biosynthesis. We highlight the genes CGL, EAAT3, AMY, and NADH, which are associated with the energy metabolism, cysteine transport, and amino acid biosynthesis of S. intermedius. We speculated that S. intermedius exposed to high salinity enhances energy metabolism, as well as Cys synthesis and transport, to mitigate oxidative stress. This study provides a theoretical reference for the healthy aquaculture of S. intermedius in high-salinity environments.

Polyunsaturated fatty acids (PUFAs) are important nutrients that play critical roles in sea urchin reproduction and early development. Strongylocentrotus intermedius, the only commercially cultured sea urchin species in China with substantial economic value, has edible gonads that are particularly rich in PUFAs. In this study, we investigated the molecular mechanisms underlying fatty acid biosynthesis and metabolism through chromosome-level genome assembly, evolutionary analysis, and transcriptomic profiling across developmental and gonadal stages. We assembled a chromosome-level genome (704.9 Mb; Scaffold N50 30 Mb) and identified an expansion of the Elovl gene family, indicating a strong endogenous capacity for fatty acid synthesis. To systematically characterize metabolic changes during gonadal development, raw RNA-seq data from previously published gonadal samples were re-analyzed together with newly generated stage 4 gonadal samples. Pathway analysis revealed that unsaturated fatty acid biosynthesis was more active during early gonadal development in males, whereas in females it remained elevated during later developmental stages, suggesting that females maintain sustained fatty acid biosynthesis throughout gonadal development, while males prioritize rapid sperm production at immature stages. During larval development, the expression of key fatty acid synthesis genes (Fads, Elovl5, Elovl4, and ACSL6) gradually decreased as planktonic larvae transitioned to benthic juveniles and endogenous lipid reserves were progressively consumed, reflecting metabolic adaptation to environmental and developmental changes. Collectively, these findings advance our understanding of fatty acid metabolism in echinoderms and provide a valuable genomic and transcriptomic resource for future studies on lipid biosynthesis and metabolism in marine invertebrates.

The present study investigated the effects of different intensities of blue light on papillae number growth and associated molecular mechanisms in the sea cucumber Apostichopus japonicus. The sea cucumber were exposed for 60 days under three blue light intensities (1500 lx, 3000 lx, and 4500 lx). Papillae numbers and body weight were measured regularly. Transcriptomic sequencing was performed to analyze gene expression differences in spine tissues. The results showed that the number of papillae was significantly highest in the sea cucumbers exposed to 1500 lx. Body weight growth was not significantly affected by any light intensity treatment. Compared with the control group, the 1500 lx group showed differentially expressed genes (DEGs) significantly enriched in pathways including the ras signaling pathway, ascorbate and aldarate metabolism, and fatty acid elongation. Seven key genes potentially related to the growth of papillae number were identified: Survivin, PHB2, SoxB, traf6, TRPML3, TGF-β1, and Rps13. In contrast, compared with the 1500 lx group, both the 3000 lx group and the 4500 lx group showed differentially expressed genes (DEGs) mainly enriched in pathways including axon regeneration, regulation of actin cytoskeleton, fc gamma R-mediated phagocytosis, and chemokine signaling. Six genes potentially inhibiting the growth of papillae number were identified: CRK, Smad4, Rac1, Arf6, ASAP2, and Wnt7. In conclusion, the light intensity of 1500 lx effectively increased the papillae number in A. japonicus. This study provides molecular evidence for enhancing papillae number in cultured sea cucumbers through light intensity regulation.

The sea urchin Glyptocidaris crenularis, is the only species of genus Glyptocidaris (family Phymosomatidae), distributed in the northern Yellow Sea of China and in parts of the Sea of Japan. As a major edible sea urchin species, it attracts significant research attention due to the nutritional and economic values. In this study, the genome of G. crenularis was constructed by using Illumina short read, Pacbio length read and Hi-C sequencing technology. The genome consists of 22 chromosomes, which is different from sea urchins within the family Strongylocentrotidae (Strongylocentrotus intermedius, Hemicentrotus pulcherrimus, and Mesocentrotus franciscanus) and the family Echinometridae (Anthocidaris crassispina) all possess 21 chromosomes number. The sequence length is 772.09 Mb, and Scaffold N50 length is 33.67 Mb. A total of 18965 genes were annotated, 94.72% of which were functionally annotated. The genome provides valuable genomic resources for the genetic analysis of important economic traits of G. crenularis and the evolution analysis of sea urchin species.

Unfavorable environments have a serious impact on sea cucumbers and even lead to diseases in aquaculture. Yellow intestinal disease has a serious effect on land-based aquaculture of sea cucumbers. This study is to clarify the effect of yellow intestinal disease on the behavior and gut health of sea cucumbers. We observed that feeding behavior significantly decreased in the sea cucumbers with yellow intestinal disease and that their righting response time was significantly longer compared to healthy individuals. Further, this study found that the heads of diseased sea cucumbers swung violently, and they preferred to stick to the wall of the tank rather than the bottom. This is contrary to sea cucumbers with enteritis disease. Additionally, we found that there was no significant difference in the thickness of the intestinal muscular layer between sea cucumbers with and without yellow intestine disease. However, the height of intestinal folds decreased, while the width significantly increased in diseased sea cucumbers. Novelly, the present study found that yellow intestinal disease did not change intestinal pepsin activity and flora abundance, although it reduced the feeding behavior of sea cucumbers and changed intestinal morphology. Yellow intestine disease is also different from the imbalance of intestinal microbiota caused by enteritis disease in sea cucumbers. Therefore, yellow intestine disease is probably not an enteritis disease, but a manifestation of sea cucumbers in the face of unfavorable environments. We suggest aquafarmers not treat sea cucumbers with yellow intestinal disease using the method to treat enteritis disease.