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Pampus argenteus demonstrates a preference for Rhopilema esculentum as prey, yet the ramifications of consuming supplemental medusa on fish microbiota and metabolism remain elusive. To elucidate these effects, 300 juvenile fish were divided into two groups: control group (C, given commercial food only) and supplemental medusa (SM) group (given supplemental medusa + commercial feed). After 15 days, fish in the SM group exhibited a significant increase in fatness, the amylase activity in the intestine significantly increased, and the intestinal microvilli were arranged more neatly. The comprehensive approach involving 16S rRNA amplicon sequencing and metabolomics was employed, leading to the identification of five genera within the SM group, namely Lactococcus, Cohaesibacter, Maritalea, Sulfitobacter, and Carnobacterium. Functional prediction analysis of the microbiota indicated that the consumption of supplemental medusa facilitated processes such as glycolysis/gluconeogenesis and amino acid absorption. Metabolomics analysis revealed significant enrichment of 85 differential metabolites, most of them belonging to fatty acids and conjugates. These differential metabolites primarily participated in processes such as amino acid metabolism, fatty acid synthesis, and disease. Notably, the consumption of medusa resulted in a significant reduction in nine lysophospholipids associated with cardiovascular disease and inflammation. Pearson's correlation coefficient analysis revealed associations between specific microorganisms and metabolites, indicating that Cobetia, Weissella, and Macrococcus exhibited an increased abundance in the SM group, positively correlating with apocynin, 12‐Hete, and delta 9‐THC‐d3. The indicator bacteria Psychrobacter reduced in the SM group, exhibiting a negative correlation with cystathionine (a compound involved in glutathione synthesis). Overall, the supplementation of medusa may confer a beneficial effect on the immunity of the fish. This study contributes to the theoretical framework for fish feed development. [ABSTRACT FROM AUTHOR]

Osteoarthritis (OA) is a common type of arthritis characterized by degeneration of the articular cartilage and joint dysfunction. Various pharmacological and non-pharmacological techniques have been used to manage these diseases. Due to the diverse therapeutic properties of marine collagen, it has received considerable attention in its pharmacological application. Thus, the purpose of this study was to compare the efficacy of jellyfish collagen, collagen peptide, other sources of marine collagen, and glycine in treating OA. In the OA rat model, an anterior cruciate ligament transection combined with medial meniscectomy surgery (ACLT + MMx) was used to induce osteoarthritis in rats. Two weeks before surgery, male Sprague–Dawley rats were fed a chow-fat diet. After 6 weeks of treatment with collagen, collagen peptide, and glycine, the results show that they could inhibit the production of proinflammatory cytokines and their derivatives, such as COX-2, MMP-13, and CTX-II levels; therefore, it can attenuate cartilage degradation. Moreover, collagen peptides can promote the synthesis of collagen type II in cartilage. These results demonstrate that collagen and glycine have been shown to have protective properties against OA cartilage degradation. In contrast, collagen peptides have been shown to show cartilage regeneration but less protective properties. Jellyfish collagen peptide at a dose of 5 mg/kg b. w. has the most significant potential for treating OA because it protects and regenerates cartilage in the knee.

Strobilation is a well-organized metamorphosis process in scyphozoan jellyfish, through which the benthic polyp develops into the pelagic medusa. So far, knowledge on the molecular mechanisms behind the drastic morphological and physiological changes remains limited. In the present study, the metabolic profiles in polyp and strobila stages of jellyfish Rhopilema esculentum were examined using ultra-performance liquid chromatography coupled to a mass spectrometer. A total of 3 071 metabolites with putative annotation were detected, of which 167 were identified as differential metabolites between the polyp and strobila. Among the metabolites, 31 significantly decreased and 136 significantly increased in abundance in the strobila. Thyroxin, one of the previously proposed strobilation inducer of Aurelia, was not detected in this study. The indole-containing compounds are known for triggering strobilation in Discomedusae. Two indole derivatives and an indole-isomer containing metabolite were detected among the most significantly increased metabolites, which may be potential endogenous molecules for strobilation initiation. The membrane-associated phospholipids and the inflammation and oxidative stress-related eicosanoids were found to have significant changes. Although the functions of these metabolites in strobilation are not yet completely known, they provide some clues to the induction of the process of strobilation and metabolic responses that take place during strobilation. [ABSTRACT FROM AUTHOR]

With the continuous development of jellyfish fisheries and food products around the world, an effective traceability system has become increasingly prominent. This study provides insight into the origin traceability and authentication of two commercially important jellyfish species, flame jellyfish Rhopilema esculentum and Nomura’s jellyfish Nemopilema nomurai, while investigating the intra- and inter-specific variation in fatty acid (FA) profiles and carbon and nitrogen stable isotope ratios (δ13C and δ15N). Results showed significant differences in FA profiles and isotopic values in fresh bell tissues between wild and farmed R. esculentum and among geographic origins, possibly due to different food sources, nutritional status, and energy costs that each group experiences at a given location. The linear discriminant analysis indicated that δ13C, δ15N, C16:0, C17:0, C18:0, C16:1n7, and C20:5n3 were suitable discriminatory variables with a high rate of correct classification for distinguishing origins of R. esculentum. In addition, inter-specific FA profiles/biomarkers, combined with isotopic values, suggests the variety of dietary sources and trophic positions of sympatric similar-sized R. esculentum and N. nomurai and the potential use of biomarkers, especially stable isotope analysis, for distinguishing sympatric jellyfish species. These results highlighted the complementarity of FA and stable isotope analyses and provide an alternative approach for improving the origin traceability and authenticity evaluation of untreated edible jellyfish. Furthermore, this study adds new information regarding the biochemical compositions of jellyfish species.

Over the past decades, jellyfish occurred increasingly and abundantly in coastal areas worldwide. Usually, biomass of jellyfish, especially when they bloom, can be determined by visual counting. However, tiny individuals of jellyfish (e.g., planulae, polyps, and ephyrae) are difficult to detect in the field. In this study, species-specific quantitative real-time PCR assays (qPCR) (SYBR Green I) targeting the mitochondrial 16S rDNA (mt-16S rDNA) of jellyfish were developed and were used to estimate the distribution and seasonal fluctuations of four jellyfish species (Nemopilema nomurai, Cyanea nozakii, Rhopilema esculentum, and Aurelia coerulea) in Jiaozhou Bay (JZB), China in 2013. The mt-16S rDNA of A. coerulea and N. nomurai was detected in most of the survey months and it peaked in July (1.03×104 copies/L) and September (1.08×106 copies/L), respectively. The mt-16S rDNA of C. nozakii occurred from August to October only with monthly mean values of 7.18–46.17 copies/L and was mainly located from the middle part to the outer part of the bay. The mt-16S rDNA of R. esculentum was the least abundant among the four species and was detected in only one sample (B2 station in March), with a value of 88.49 copies/L. The Spearman correlation test revealed that phytoplankton biomass was significantly and positively correlated with the mt-16S rDNA abundance of A. coerulea (R=0.37, P<0.01) and negatively with the mt-16S rDNA of N nomurai (R=-0.36, P<0.01). The qPCR assay will enable the identification and quantification of jellyfish species in their whole life history and can be used as an approach in combination of the traditional jellyfish survey. [ABSTRACT FROM AUTHOR]

Venomics, the study of biological venoms, could potentially provide a new source of therapeutic compounds, yet information on the venoms from marine organisms, including cnidarians (sea anemones, corals, and jellyfish), is limited. This study identified the putative toxins of two species of jellyfish—edible jellyfish Rhopilema esculentum Kishinouye, 1891, also known as flame jellyfish, and Amuska jellyfish Sanderia malayensis Goette, 1886. Utilizing nano-flow liquid chromatography tandem mass spectrometry (nLC–MS/MS), 3000 proteins were identified from the nematocysts in each of the above two jellyfish species. Forty and fifty-one putative toxins were identified in R. esculentum and S. malayensis, respectively, which were further classified into eight toxin families according to their predicted functions. Amongst the identified putative toxins, hemostasis-impairing toxins and proteases were found to be the most dominant members (>60%). The present study demonstrates the first proteomes of nematocysts from two jellyfish species with economic and environmental importance, and expands the foundation and understanding of cnidarian toxins.

Strobilation is a unique asexual reproduction mode of scyphozoan jellyfish, through which benthic polyp develops into pelagic medusa. It is an orderly metamorphosis process triggered by environmental signals. However, the knowledges of molecular mechanisms under the drastic morphological and physiological changes are still limited. In this study, the transcriptomes from polyps to juvenile medusae at different stages were characterized by RNA-seq in scyphozoan jellyfish Rhopilema esculentum. Among 96,076 de novo assembled unigenes, 7090 differentially expressed genes (DEGs) were identified during the developmental stages. The co-expression pattern analysis of DEGs yielded 15 clusters with different expression patterns. Among them, a cluster with 388 unigenes was related to strobila. In this specific cluster, the GO terms related to "sequence-specific DNA binding transcription factor activity" and "sequence-specific DNA binding" were significantly enriched. Transcription factors, including segmentation protein even-skipped-like, segmentation polarity protein engrailed-like, homeobox proteins Otx-like, Twist-like and Cnox2-Pc-like, as well as genes such as RxR-like and Dmrtf-like, were identified to be potentially involved in strobilation. Their expression patterns and the other 11 TFs/genes involved in strobilation were confirmed with qRT-PCR methods. The present study pointed out the role of transcription factors in strobilation and produced a list of novel candidate genes for further studies. It could provide valuable information for understanding the molecular mechanisms of jellyfish strobilation. [ABSTRACT FROM AUTHOR]

In this study, single nucleotide polymorphism (SNP), microsatellite (SSR) and differentially expressed genes (DEGs) in the oral parts, gonads, and umbrella parts of the jellyfish Rhopilema esculentum were analyzed by RNA-Seq technology. A total of 76.4 million raw reads and 72.1 million clean reads were generated from deep sequencing. Approximately 119,874 tentative unigenes and 149,239 transcripts were obtained. A total of 1,034,708 SNP markers were detected in the three tissues. For microsatellite mining, 5088 SSRs were identified from the unigene sequences. The most frequent repeat motifs were mononucleotide repeats, which accounted for 61.93%. Transcriptome comparison of the three tissues yielded a total of 8841 DEGs, of which 3560 were up-regulated and 5281 were down-regulated. This study represents the greatest sequencing effort carried out for a jellyfish and provides the first high-throughput transcriptomic resource for jellyfish. [ABSTRACT FROM AUTHOR]

Ten microsatellite markers were used to analyze the levels of genetic diversity and inbreeding in a hatchery release population of Rhopilema esculentum Kishinouye (Scyphozoa: Rhizostomatidae). A total of 85 alleles were detected in 600 individuals. Within-population levels of observed ( H ) and expected ( H ) heterozygosity ranged from 0.152 to 0.839 (mean=0.464) and from 0.235 to 0.821 (mean=0.618), respectively. The polymorphism information content (PIC) of each marker ranged from 0.207 to 0.795 with an average of 0.580, indicating that the hatchery population maintained a high level of genetic diversity. Inbreeding levels were estimated in the hatchery population and the inbreeding coefficient was 0.203. This result revealed that a certain level of inbreeding occurred within the population. Meanwhile, we also determined genetic diversity at the clone level. Several polyps from the same scyphistomae were genotyped at the ten microsatellite loci and there was virtually no difference in their genotypes. Furthermore, we calculated the probabilities of exclusion. When both parents were known, the average exclusion probability of ten loci was 99.99%. Our data suggest that the ten microsatellite markers can not only be used to analyze the identity of individuals but they can also be applied to parentage identification. Our research provides a theoretical basis and technical support for genetic diversity detection and reasonable selection of R. esculentum hatchery populations. These findings support the use of releasing studies and conservation of R. esculentum germplasm resources. [ABSTRACT FROM AUTHOR]

The study aimed to evaluate nutraceutical potential of three commercially significant edible jellyfish species ( Acromitus hardenbergi , Rhopilema hispidum and Rhopilema esculentum ). The bell and oral arms of these jellyfishes were analyzed for their proximate composition, calorific value, collagen content, amino acid profile, chemical score and elemental constituent. In general, all jellyfish possessed low calorific values (1.0–4.9 kcal/g D.W.) and negligible fat contents (0.4–1.8 g/100 g D.W.), while protein (20.0–53.9 g/100 g D.W.) and minerals (15.9–57.2 g/100 g D.W.) were found to be the richest components. Total collagen content of edible jellyfish varied from 122.64 to 693.92 mg/g D.W., accounting for approximately half its total protein content. The dominant amino acids in both bell and oral arms of all jellyfish studied includes glycine, glutamate, threonine, proline, aspartate and arginine, while the major elements were sodium, potassium, chlorine, magnesium, sulfur, zinc and silicon. Among the jellyfish, A. hardenbergi exhibited significantly higher total amino acids, chemical scores and collagen content ( p < 0.05) compared to R. hispidum and R. esculentum . Having good protein quality and low calories, edible jellyfish is an appealing source of nutritive ingredients for the development of oral formulations, nutricosmetics and functional food. [ABSTRACT FROM AUTHOR]

The complete mitochondrial genome of Rhopilema esculentum collected from Jiaozhou Bay, China, was determined by next-generation sequencing. The mitogenome is a circular molecule 15,855 bp in length, including 13 protein-coding genes (Cox 1, Cox2, Atp 8, Atp 6, Cox 3, ND2, ND5, ND 6, ND3, ND4L, ND1,ND4, Cytb), 5 tRNAs (tRNA-Trp, tRNA-Met, tRNA-Leu, tRNA-Ser, tRNA-Gln), 2 rRNA genes (small subunit RNA and large subunit RNA) and 1 putative control region. The phylogenetic tree in the related species showed that R. esculentum is close to Nemopilema nomurai.

A species of edible Scyphomedusae jellyfish has been used as food by the local people in Ganghwado, Korea since the 1990s. In order to identify this jellyfish, we collected specimens in Ganghwado during September 2013, and compared these specimens with original descriptions made by Kishinouye (1890). Mitochondrial cytochrome oxidase subunit 1 (CO1) sequences of these specimens were compared with those of Rhopilema esculentum retrieved from GenBank. Our specimens were also compared with jellyfish collected in China, previously confirmed as R. esculentum, based on morphological characters and DNA sequences. Using these two methods, the jellyfish specimens caught in Ganghwado were correctly identified as R. esculentum, a species new to Korean waters. This edible jellyfish has been named 'Gisusik-Yonghaepari' as Korean name. [ABSTRACT FROM AUTHOR]

Jellyfish are sometimes considered as valueless because of their supposed low nutritive content. Here, we conducted feeding experiments on silver pomfret juveniles to evaluate the dietary value of jellyfish. Six treatments, including a starvation treatment (S) and five feeding treatments, with Aurelia aurita ( AA), Rhopilema esculentum ( RE), artificial diet (AD), both A. aurita and artificial diet ( A&A), and both R. esculentum and artificial diet ( R&A), were carried out to compare fish survival rates and growth performance. Fish with S treatment showed a 48% mortality rate and reduced body weight, whereas fish with AA and RE treatments showed no death and much increased body weight. Fish with A&A and R&A treatments exhibited a much faster growth than that with AD treatment. Further, the effects of diet on biochemical composition of silver pomfrets were explored. Monounsaturated fatty acid (MUFA), seven different fatty acids, and six different essential amino acids (EAAs) were showed to be good indicators to assess silver pomfrets' response to their prey. Our experiment indicated that the jellyfish, A. aurita and R. esculentum, can provide energy for silver pomfrets' metabolism and growth, and as supplemental food are suitable for rearing silver pomfret juveniles. [ABSTRACT FROM AUTHOR]

Fifteen polymorphic microsatellite loci were developed and characterized for Rhopilema esculentum using a (GT)-enriched genomic library. The numbers of alleles per locus ranged from 2 to 12, and the observed and expected heterozygosities varied from 0.0417 to 0.8750 and from 0.0086 to 0.7055, respectively. These markers will be helpful for QTL mapping, molecular breeding and investigation of population genetic diversity in R. esculentum. [ABSTRACT FROM AUTHOR]

The current study explored Aurelia aurita and Rhopilema esculentum consumption by silver pomfret juveniles, as well as their prey selection between the two jellyfish species. Silver pomfret juveniles weighing 1±0.1 g actively preyed on both the species. Their daily A. aurita consumption was 11.6 times their own body weights regardless of the size of A. aurita medusae. Their daily R. esculentum consumption was 13, 9.1, 5, and 4.1 times their own body weights when the R. esculentum medusae were 10, 20, 30, and 40 mm in bell diameter, respectively. The survival rates of the R. esculentum were higher than those of the A. aurita. When the R. esculentum medusae were more than 30 mm in bell diameter, their survival rate exceeded 92%. Silver pomfrets serve as a type of potential predators on A. aurita in coastal waters, and they have little influence on R. esculent um with a size exceeding 30 mm. Besides, A. aurita may be able to be used as fish prey in silver pomfret artificial breeding. [ABSTRACT FROM AUTHOR]

Amplified fragment length polymorphisms (AFLP) markers were developed to assess the genetic variation of populations and clones of Rhopilema esculentum Kishinouye (Scyphozoa, Rhizostomatidae). One hundred and seventy-nine loci from 56 individuals of two hatchery populations and two wild populations were genotyped with five primer combinations. The polymorphic ratio, Shannon's diversity index and average heterozygosity were 70.3%, 0.346 and 0.228 for the white hatchery population, 74.3%, 0.313, and 0.201 for the red hatchery population, 79.3%, 0.349, and 0.224 for the Jiangsu wild population, and 74.9%, 0.328 and 0.210 for the Penglai wild population, respectively. Thus, all populations had a relatively high level of genetic diversity. A specific band was identified that could separate the white from the red hatchery population. There was 84.85% genetic differentiation within populations. Individual cluster analysis using unweighted pair-group method with arithmetic mean (UPGMA) suggested that hatchery populations and wild populations could be divided. For the hatchery populations, the white and red populations clustered separately; however, for the wild populations, Penglai and Jiangsu populations clustered together. The genetic diversity at the clone level was also determined. Our data suggest that there are relatively high genetic diversities within populations but low genetic differentiation between populations, which may be related to the long-term use of germplasm resources from Jiangsu Province for artificial seeding and releasing. These findings will benefit the artificial seeding and conservation of the germplasm resources. [ABSTRACT FROM AUTHOR]

Abstract: Angiotensin-converting enzyme (ACE) inhibitory, antihypertensive and antihyperlipidaemic activities of protein hydrolysates (RPH) from the jellyfish Rhopilema esculentum were investigated. R. esculentum was hydrolysed sequentially with pepsin and papain, and then the hydrolysate was ultrafiltered with a 2000Da cut-off membrane. It was found that RPH contained high levels of Gly, Glu, Pro, Asp and Ala, having potential ACE inhibitory activity in vitro with an IC50 of 1.28mg/ml. It was also found that systolic blood pressure was reduced markedly in spontaneously hypertensive rats after single and chronic oral administration of RPH, indicating that RPH had an antihypertensive effect. In addition, oral administration of RPH decreased total serum cholesterol and triglyceride, and increased high-density lipoprotein cholesterol in rats fed with high-fat diet. These results indicate that RPH may prove to be a promising functional food for the prevention and treatment of hypertension and hyperlipidaemia. [Copyright &y& Elsevier]

Abstract: Three edible jellyfish Rhopilema hispidum, R. esculentum and Nemopilema nomurai are virulent to humans. We monitored one patient that was stung sequentially by these three species of jellyfish. The first species caused a persistent eruption, the second produced significant pruritus and the last induced only cutaneous symptoms rather than severe systemic disorders reported for its Chinese counterpart. The lesions of these jellyfish species are characteristic and common in workers harvesting medusae. There is no significant incidence of symptoms by ingesting these animals. [Copyright &y& Elsevier]

Venomics, the study of biological venoms, could potentially provide a new source of therapeutic compounds, yet information on the venoms from marine organisms, including cnidarians (sea anemones, corals, and jellyfish), is limited. This study identified the putative toxins of two species of jellyfish—edible jellyfish Rhopilema esculentum Kishinouye, 1891, also known as flame jellyfish, and Amuska jellyfish Sanderia malayensis Goette, 1886. Utilizing nano-flow liquid chromatography tandem mass spectrometry (nLC–MS/MS), 3000 proteins were identified from the nematocysts in each of the above two jellyfish species. Forty and fifty-one putative toxins were identified in R. esculentum and S. malayensis, respectively, which were further classified into eight toxin families according to their predicted functions. Amongst the identified putative toxins, hemostasis-impairing toxins and proteases were found to be the most dominant members (>60%). The present study demonstrates the first proteomes of nematocysts from two jellyfish species with economic and environmental importance, and expands the foundation and understanding of cnidarian toxins. [ABSTRACT FROM AUTHOR]

Background Jellyfish belong to the phylum Cnidaria, which occupies an important phylogenetic location in the early-branching Metazoa lineages. The jellyfish Rhopilema esculentum is an important fishery resource in China. However, the genome resource of R. esculentum has not been reported to date. Findings In this study, we constructed a chromosome-level genome assembly of R. esculentum using Pacific Biosciences, Illumina, and Hi-C sequencing technologies. The final genome assembly was ∼275.42 Mb, with a contig N50 length of 1.13 Mb. Using Hi-C technology to identify the contacts among contigs, 260.17 Mb (94.46%) of the assembled genome were anchored onto 21 pseudochromosomes with a scaffold N50 of 12.97 Mb. We identified 17,219 protein-coding genes, with an average CDS length of 1,575 bp. The genome-wide phylogenetic analysis indicated that R. esculentum might have evolved more slowly than the other scyphozoan species used in this study. In addition, 127 toxin-like genes were identified, and 1 toxin-related "hub" was found by a genomic survey. Conclusions We have generated a chromosome-level genome assembly of R. esculentum that could provide a valuable genomic background for studying the biology and pharmacology of jellyfish, as well as the evolutionary history of Cnidaria. [ABSTRACT FROM AUTHOR]

The complete mitochondrial genome of Rhopilema esculentum collected from Jiaozhou Bay, China, was determined by next-generation sequencing. The mitogenome is a circular molecule 15,855 bp in length, including 13 protein-coding genes (Cox 1, Cox2, Atp 8, Atp 6, Cox 3, ND2, ND5, ND 6, ND3, ND4L, ND1,ND4, Cytb), 5 tRNAs (tRNA-Trp, tRNA-Met, tRNA-Leu, tRNA-Ser, tRNA-Gln), 2 rRNA genes (small subunit RNA and large subunit RNA) and 1 putative control region. The phylogenetic tree in the related species showed that R. esculentum is close to Nemopilema nomurai. [ABSTRACT FROM AUTHOR]