Search

The sea cucumber Apostichopus japonicus is one of the most dominant and economically important aquaculture species in China. Saponin, which possesses notable biological and pharmacological properties, is a key determinant of the nutritional and health value of A. japonicus. In the present study, we amplified the full-length cDNA of a phosphomevalonate kinase (PMK) gene (named AjPMK) using rapid amplification of cDNA ends (RACE). Subsequently, we engineered a recombinant AjPMK (rAjPMK) protein and assessed its enzymatic activity by enzyme-linked immunosorbent assay (ELISA). Proteins that interact with rAjPMK were screened and identified via pull-down assay combined with liquid chromatography with tandem mass spectrometry (LC-MS/MS). We found that the full-length cDNA of AjPMK contained 1354 bp and an open reading frame (ORF) of 612 bp. The AjPMK protein was predicted not to contain a signal peptide but to contain a phosphonolate kinase domain seen in higher eukaryotes and a P-loop with a relatively conserved nucleoside triphosphate hydrolase domain. The molecular weight of the AjPMK protein was estimated to be 23.81 kDa, and its isoelectric point was predicted to be 8.72. Phylogenetic analysis showed that AjPMK had a closer evolutionary relationship with genes from starfish than with those of other selected species. Besides, we found that rAjPMK synthesized mevalonate-5-diphosphate, interacted either directly or indirectly with crucial pattern recognition receptors (PRRs) and was regulated by immune-related processes, including antioxidative reactions, stress resistance responses and enzyme hydrolysis. Moreover, AjPMK also interacted with farnesyl pyrophosphate synthase, an enzyme reported to be involved in saponin biosynthesis. Together, our findings implied that AjPMK may be directly involved in saponin biosynthesis and the regulation of various innate immune processes. • A phosphomevalonate kinase (PMK) gene was identified in sea cucumber Apostichopus japonicus. • AjPMK is involved in sea cucumber saponin biosynthesis. • AjPMK might be regulated by multiple immune processes. [ABSTRACT FROM AUTHOR]

Summary: Nowadays, the true economic and nutritional value of food is underpinned by both origin and quality traits, more often expressed as increased quality benefits derived from the origin source. Gut microbiota contribute to food metabolism and host health, therefore, it may be suitable as a qualifying indicator of origin and quality of economic species. Here, we investigated relationships between the gut microbiota of the sea cucumber (Apostichopus japonicus), a valuable aquaculture species in Asia, with their origins and quality metrics. Based on data from 287 intestinal samples, we generated the first biogeographical patterns for A. japonicus gut microbiota from origins across China. Importantly, A. japonicus origins were predicted using the random forest model that was constructed using 20 key gut bacterial genera, with 97.6% accuracy. Furthermore, quality traits such as saponin, fat and taurine were also successfully predicted by random forest models based on gut microbiota, with approximately 80% consistency between predicted and true values. We showed that substantial variations existed in the gut microbiota and quality variables in A. japonicus across different origins, and we also demonstrated the great potential of gut microbiota to track A. japonicus origins and predict their quality traits. [ABSTRACT FROM AUTHOR]

The sea cucumber Apostichopus japonicus is an important aquaculture species in China because of its high nutritional and medicinal values. Gender, as a factor affecting the physiology of organisms, is always considered when improving the breeding efficiency of economically important animals. In the present study, protein expression profiles of the gonads and tube feet of male and female A. japonicus were investigated using a comparative proteomics approach. A set of 7499 proteins were identified, which covered a broad range of functions based on function annotations. A significant difference in protein expression profiles was observed between the gonads and tube feet of A. japonicus ; gonads showed more apparent gender differences than tube feet. Moreover, the findings revealed that male A. japonicus had more specific functions and most of these functions were associated with energy consumption. Further analyses suggested that the regulation of ERK activity and the capacity of tyrosine production and virus immunity might be more powerful in male and female A. japonicus , respectively. Some candidate proteins were also recognized as potential targets for gender identification of A. japonicus. Overall, our study provides new insights into the understanding of molecular mechanisms underlying gender-based physiological differences in A. japonicus. The current study aimed to reveal gender differences in the physiological characteristics of gonads and tube feet of the sea cucumber A. japonicus. To the best of our knowledge, this is the first proteomics study to analyze the differences in the protein expression profiles of external organs between male and female A. japonicus. The analysis revealed gender differences in the protein expression profiles of both gonads and tube feet of A. japonicus , and the gender differences in gonads were quite apparent. Moreover, according to the recognition of differentially expressed proteins and the enrichment analyses based on Kyoto Encyclopedia of Genes and Genomes, a draft view of how the physiological functions of A. japonicus were affected by gender was obtained. Male A. japonicus could have more specific functions related to energy consumption than females. The regulation of ERK activity and virus immunity might be more robust in male and female A. japonicus , respectively. Some candidate proteins were also recognized as potential targets for gender identification of A. japonicus. The findings presented here will improve the understanding of researchers about the molecular mechanisms underlying gender-based differences in A. japonicus and contribute to the meticulous breeding of A. japonicus. [Display omitted] • Gender-based physiological differences in sea cucumbers were investigated. • Gonads showed more apparent gender differences than tube feet in sea cucumber. • The regulation of ERK activity might be more robust in male sea cucumbers. • Tyrosine production and virus immunity might be more robust in female sea cucumbers. • Some candidate gender identification targets were recognized from male tube feet. [ABSTRACT FROM AUTHOR]