Ring Box Protein-1 (RBX1) is an essential component of the Skp1-cullin-F-box protein (SCF) E3 ubiquitin ligase, which is involved in the regulation of oocyte maturation in the form of ubiquitination substrate modification. In this study, a sequence of RBX1 (Sp-RBX1) was identified and analyzed using bioinformatics methods from the transcriptome data of Scylla paramamosain. The length of Sp-RBX1 cDNA sequence was 1247 bp, consisting of a 336 bp open reading frame (ORF). Sequence analysis revealed that the protein contained a C-terminal modified RING-H2 finger domain, with two zinc binding sites and a Cullin binding site, classifying it as a member of the RBX1 superfamily. The results of real-time fluorescence quantitative PCR (RT-qPCR) showed that Sp-RBX1 expression in the ovary was low at stages I and II, then significantly increased from stage III to V (p < 0.05), which indicated that it might be closely related to the maturation of oocytes. It also peaked at stage II in the hepatopancreas, then sharply declined from stages III to V. The expression pattern might be related to the accumulation of fat in the early development of hepatopancreas. Furthermore, we characterized the expression of Sp-RBX1 induced by follicle-stimulating hormone (FSH) and estradiol (E2) hormones. The results showed that the expression in the ovary was up-regulated by FSH and significantly inhibited by E2. The expression in the hepatopancreas increased only at 0.5 µmol/L concentration of FSH, and decreased in other groups. Conversely, it was up-regulated by E2. Thus, the expression of Sp-RBX1 was influenced by FSH in a concentration-dependent manner. These findings could offer valuable insights for further research on ovarian maturation in crustaceans.

We analyzed the differences in growth between female and male juvenile mud crabs (Scylla paramamosain Estampador, 1950) under standard individual rearing conditions using genetic sex makers we developed. The normality tests of the carapace length (CL) and width (CW) at each stages indicated that both CL and CW of mix sexes followed normal distribution model from the C1 to C3 stages, but not from the C4 and the subsequent stages, while these traits followed normal distribution model at the sex separated populations. No significant differences were observed in the CL, CW. and molting intervals between females and males from C1 to C3. The molting interval from C3 to C4 was shorter in females than in males, and the CW from C4 stages was significantly larger in females than in males, but the CL from C5 stages was significantly larger in males than in females. These observations might last into the adult stages, since the CW in similar rank adults was significantly larger in females than in males, and CL was the opposite. These studies provided for the first time direct evidence for the differentiation of growth between the sexes in mud crabs, providing insights for the breeding and aquaculture of this economically important species.

Betaine homocysteine S-methyltransferase gene 1 ( BHMT1 ) encoded betaine homocysteine S-methyltransferase (BHMT) catalyzes the homocysteine-to-methionine reaction using betaine as a methyl donor. Previously, we found that BHMT was lost in the genome of the insect clade of arthropods, but was highly expressed in the mandibular organ (MO) of the mud crab Scylla paramamosain (Sp). To further explore its significance, we performed a primary regulatory analysis of BHMT in mud crabs. The open reading frame (ORF) length of Sp-BHMT1 was 1203 bp, encoding 400 amino acids. Sequence alignment revealed that BHMT1 was highly conserved in different animals, and its identity was higher in more closely related species. Sp-BHMT1 had the highest expression in the MO of both sexes, while its expression in the MO was 1.6-fold higher in males than in females; similar results were also found in the cerebral ganglion, hepatopancreas, and thoracic ganglia tissues. During larval development, Sp-BHMT1 was weakly expressed on most days but was significantly elevated on the first day of the Zoea 2nd (Z2) and Z3 stages. Sp-BHMT1 exhibited the highest expression at a salinity of 10 %o and the lowest at a salinity of 30 %o. With decreasing salinity, the expression of Sp-BHMT1 increased significantly at 6 h and then returned to baseline at 8 h. After starvation treatment, the expression of Sp-BHMT1 was significantly upregulated compared to that in the feed group at all examined time points, with a peak expression at 18:00 on the third day in the starvation group. Kr & uuml;ppel homolog 1 (Kr-h1 ), a methyl farnesoate (MF) signal gene, could increase Sp-BHMT1 expression under low salinity and starvation, suggesting that a "salinity/starvation -> BHMT1 -> MF biosynthesis" regulatory axis might exist in crabs. This study provides valuable insights into the functional study of Sp-BHMT1 and MF biosynthetic regulation.

Environmental DNA (eDNA) metabarcoding, a non-invasive method for detecting aquatic organisms, has been widely used in phytoplankton diversity assessment. The Arabian Sea (AS) and the Bay of Bengal (BB), the two major ocean basins of the Northern Indian Ocean, exhibit differences in various aspects due to monsoonal influences. However, few eDNA studies have focused on the comparative research on phytoplankton communities in these two regions. To address this gap, in this study, a comparative analysis of phytoplankton community structure and stability was conducted in the AS and BB using eDNA metabarcoding. Clear differences in diversity and composition of phytoplankton communities between the two regions were observed. Higher richness and diversity were found in the BB than in the AS, and the differences in phytoplankton community structure were primarily driven by the nestedness process. Moreover, dinoflagellates were observed as the dominant taxa, and some dinoflagellate taxa showed significant differences between the two regions. Community assembly mechanism analysis revealed that the stochastic processes exhibited a weaker impact in the AS. Stability assessments, which combined co-occurrence network analysis and the metric of average variability degree, revealed higher community stability in the BB. These results not only confirmed the efficacy of eDNA metabarcoding in assessing phytoplankton diversity and stability, but also provided data support for the conservation of aquatic biodiversity and sustainable ecological management in the Northern Indian Ocean.

The mud crab, Scylla paramamosain , is an economically important aquaculture species in China, and crabs of different sexes show different growth performance, size, economic value, etc. In most cases, female crabs are more popular in the market than males. In this study, we compared the growth performance of the mud crab under different female-to-male sex ratios, including all female (1:0), nine females to one male (9:1), three females to one male (3:1), fifty-fifty (1:1) and all males (0:1). The results indicated that after one or two moulting cycles (20 days), the 1:0 groups had the highest survival rates, while the 3:1 had the lowest. However, after 60 days, the trend reversed, the 3:1 group had the highest survival rates, whereas the 1:0 group fell to the lowest. The average body weight, carapace length, and carapace width of female crabs were higher in the 3:1 group than in the 9:1 and 1:1 groups, while these indexes in male crabs were higher in the 9:1 and 1:1 groups than in the 3:1 groups, and neither 1:0 or 0:1 had the greatest growth performance when compared with the mixed-sexes groups in this study. Intriguingly, the sex ratio in all mixed-culture groups was approaching 2:1, suggesting that the final survival rate in the culture population of the mud crab might be not only be influenced by the different growth speed between different sexes, but also by the sex ratio, suggesting that the 2:1 to 3:1 might be the social female-to-male sex ratios in the natural, reproductive mud crab population. This study provides various valuable insights that may give some impetus to the mud crab aquaculture industry.

Bait feeding plays a pivotal role in the artificial nursery process, as different baits can significantly influence water quality and microbial community structure, thereby directly affecting the growth and development of cultured organisms. In this study, four types of baits, including live Artemia nauplii (AN), frozen copepods (FC), frozen Artemia nauplii (FA), and formulated diet (FD) were used to feed megalopa-stage mud crabs (Scylla paramamosain) until their metamorphosis into the first juveniles. The effects on water quality, microbial community structure, metamorphosis survival rate, and molting duration were statistically analyzed. Results indicated that the AN group had 88 unique bacteria OTUs, followed by 80, 64 and 27 unique OTUs in the FA, FD and FC groups, respectively. Proteobacteria predominated in both AN and FA groups, while Bacteroidetes demonstrated the highest percentage in the FC and FD groups. Actinobacteria maintained consistently low relative abundance in all treatments. The FA group exhibited the highest Chao1, ACE and observed richness indices (P > 0.05), suggesting the greatest bacterial community richness. The AN group displayed the highest Pielou’s evenness and Shannon index, along with the lowest Simpson′ index (D) (P < 0.05), indicating a more uniform species distribution and higher community diversity. In addition, the AN group exhibited the lowest concentrations of ammonia nitrogen and nitrite among the four treatments. Moreover, the AN group showed the highest abundance of the beneficial genus Marivita, whereas the FD, FC, and FA groups had a significant increase in the harmful genus Tenacibaculum. Compared with those in the FA, FC and FD groups, the megalopae in the AN group also demonstrated the highest metamorphosis survival rate and the shorter molting duration, underscoring the critical role of live Artemia nauplii in improving water quality, and stabilizing microbial communities. These findings suggested that live Artemia nauplii were the optimal feed choice for enhancing the success of S. paramamosain megalopa breeding. Future studies could explore the integration of appending probiotics and periodic removal of harmful bacteria in the aquaculture water to further optimize microbial structure, thereby improving the metamorphosis survival rate of S. paramamosain megalopa. Moreover, strategies such as partial substitution of live Artemia nauplii with frozen Artemia could be investigated to reduce seedling cultivation costs and advance S. paramamosain aquaculture technology in the further research.

High mortality associated with pathogenic bacteria is one of the huge obstacles to S. paramamosain aquaculture. Few studies have identified the effects of potentially pathogenic bacteria in water environment on the cultivation of ovigerous crabs. Herein, we gathered water samples (WH and JD) from different culture periods of ovigerous mud crabs and red plaque samples during mud crab disease outbreaks, and utilized Illumina metagenomic sequencing and full-length 16S rRNA sequencing to delve into the microbial composition in the mariculture environment and identify potentially pathogenic bacteria. A total of 241 phyla, 5494 genera and 24846 species from WH and JD were detected, with Proteobacteria and Bacteroidota dominant. The diversity results suggested that the JD samples exhibited higher abundance of these microbiota compared to the WH samples. Full-length 16S rRNA gene sequencing assigned the red plaque bacterial community to 84 species, belonging to 96 OTUs, most of which were attributed to Proteobacteria and Firmicutes. Several species belonging to Vibrio were found in both the red plaque and JD water samples, such as Vibrio alginolyticus and Vibrio fluvialis, implying that genus Vibrio might be one of the potential predisposing bacteria leading to the death of the S. paramamosain broodstock. The number of common bacterial species among the red plaque, JD and WH samples was 43, mainly belonging to the genus Vibrio, Serratia, Sphingomonas, Pseudomonas, Pseudochrobactrum, Klebsiella, Comamonas, Exiguobacterium, and Bacillus, implying that these bacteria could be potentially conditioned pathogenic bacteria. Most species of bacteria in the red plaque samples could be found in JD, indicating that the bacterial species in mariculture environment may affect the composition of pathogenic bacteria. Our findings provide a theoretical basis for the notion of some bacteria acting as a potential pathogen source in the mariculture environment during S. paramamosain broodstock cultivation.

The mud crab, Scylla paramamosain, is an economically important aquaculture species in China, and crabs of different sexes show different growth performance, size, economic value, etc. In most cases, female crabs are more popular in the market than males. In this study, we compared the growth performance of the mud crab under different female-to-male sex ratios, including all female (1:0), nine females to one male (9:1), three females to one male (3:1), fifty-fifty (1:1) and all males (0:1). The results indicated that after one or two moulting cycles (20 days), the 1:0 groups had the highest survival rates, while the 3:1 had the lowest. However, after 60 days, the trend reversed, the 3:1 group had the highest survival rates, whereas the 1:0 group fell to the lowest. The average body weight, carapace length, and carapace width of female crabs were higher in the 3:1 group than in the 9:1 and 1:1 groups, while these indexes in male crabs were higher in the 9:1 and 1:1 groups than in the 3:1 groups, and neither 1:0 or 0:1 had the greatest growth performance when compared with the mixed-sexes groups in this study. Intriguingly, the sex ratio in all mixed-culture groups was approaching 2:1, suggesting that the final survival rate in the culture population of the mud crab might be not only be influenced by the different growth speed between different sexes, but also by the sex ratio, suggesting that the 2:1 to 3:1 might be the social female-to-male sex ratios in the natural, reproductive mud crab population. This study provides various valuable insights that may give some impetus to the mud crab aquaculture industry.

Background: Snipe eels (family Nemichthyidae) are a group of pelagic fishes with unique specializations; yet, species within this study are not well-studied due to a lack of molecular data. As typical mesopelagic-to-bathypelagic fishes, snipe eels exhibit extreme body elongation, reduced skeletal ossification, and highly specialized beak-like jaws that facilitate survival in deep-sea midwater environments. Methods: The complete mitochondrial genome of the deep-sea eel Nemichthys curvirostris (Anguilliformes: Nemichthyidae) was sequenced and annotated, representing the first mitogenomic resource for this species. The phylogenetic position of N. curvirostris was also explored. Results: The circular genome of N. curvirostris was determined to be 16,911 bp in length and contained 37 genes, including 13 protein-coding genes, 22 tRNAs, 2 rRNAs, and a single control region, with an overall A + T bias of 56.67%. The maximum-likelihood phylogeny inferred from concatenated mitochondrial protein-coding genes recovered a well-supported monophyletic Nemichthys clade, with N. curvirostris positioned as the sister taxon to N. scolopaceus. The genera Avocettina and Labichthys were recovered as sister taxa, and Nemichthys clustered within a broader clade alongside them. The COX1 haplotype phylogeny showed that the two public database sequences (HQ563894.1 and MN123435.1) appeared as long, isolated branches outside the main N. curvirostris lineage, with COX1 genetic distances from typical N. curvirostris haplotypes reaching 12-13%, far exceeding the expected range of intraspecific variation. Conclusions: This mitogenome provides a valuable molecular resource for phylogenetic, evolutionary, and population genetic studies of deep-sea Anguilliformes.

In the present study, histopathological changes in the gills and the expression of genes related to osmotic pressure regulation in larval mud crab, Scylla paramamosain, were examined under different conditions of salinity stress. Notable alterations in gill tissue were observed in low salinity environments (5 ppt) compared to normal salinity (20 ppt). The gill filaments from the low salinity stress groups became shorter and thicker over time, resulting in severe morphological damage. Quantitative real time PCR (qRT-PCR) analysis indicated a reduction in NKCC (Na+-K+-Cl-- cotransporter) expression under both low and high salinity conditions. NKCC expression gradually decreased over time in low salinity conditions. However, expression was only slightly elevated at 2 hours in high salinity conditions. These findings suggest that the NKCC transport function is inhibited to prevent salinity-induced damage. Conversely, CA gene expression levels increased after 2 hours across all salinity conditions and the highest levels were observed in the 5 ppt group. Regardless of salinity levels, CA showed a positive response to salinity changes, which supported the maintenance of normal physiological functions. This experiment would be helpful for understanding the impact of salinity stress on osmotic pressure and ion regulation under different salinity conditions in S. paramamosain.

As a prerequisite for the success of embryo development, embryonic genome activation (EGA) is an important biological event in which zygotic gene products in the embryo are activated to replace maternal-derived transcripts. Although EGA has been extensively studied in a large number of vertebrates and invertebrates, there is a lack of information regarding this event in crustacean crab. In this study, the timing of EGA was confirmed by examining a transcriptomic dataset of early embryonic development, including mature oocytes and embryos through six early developmental stages, and signaling pathways associated with EGA were identified in the mud crab, S. paramamosain. The comprehensive transcriptomic data identified a total of 53,915 transcripts from these sequencing samples. Notable transcriptomic change was evident at the 1-cell stage, indicated by a 36% transcript number shift and a reduction in transcript fragment length, compared to those present in the mature oocytes. Concurrently, a substantial increase in the expression of newly transcribed transcripts was observed, with gene counts reaching 3485 at the 1-cell stage, indicative of the onset of EGA. GO functional enrichment revealed key biological processes initiated at the 1-cell stage, such as protein complex formation, protein metabolism, and various biosynthetic processes. KEGG analysis identified several critical signaling pathways activated during EGA, including the "cell cycle," "spliceosome," "RNA degradation", and "RNA polymerase", pathways. Furthermore, transcription factor families, including zinc finger, T-box, Nrf1, and Tub were predominantly enriched at the 1-cell stage, suggesting their pivotal roles in regulating embryonic development through the targeting of specific DNA sequences during the EGA process. This groundbreaking study not only addresses a significant knowledge gap regarding the developmental biology of S. paramamosain, especially for the understanding of the mechanism underlying EGA, but also provides scientific data crucial for the research on the individual synchronization of seed breeding within S. paramamosain aquaculture. Additionally, it serves as a reference basis for the study of early embryonic development in other crustacean species.

Abstract The asymmetry trait in brachyuran crabs is mostly expressed by the different sizes or particular details of the two chelae. The causes for this asymmetry have been rarely investigated in the economically important crab Scylla paramamosainEstampador, 1950. We found that the asymmetric chelae first appeared in the megalopa stage. The examination of four “right-handed” and two “left-handed” mothers and their 521 megalopa offspring indicated that this trait might not be influenced by dominant alleles, since 86.0% –99.0% of megalopae exhibited the right-handed phenotype in the four offspring of the right-handed mother, whereas about 93.1% and 100% megalopae exhibited the right-handed phenotype in the two left-handed-mothers’ offspring. The percentage of left-handed individuals at different stages also supports this hypothesis. We provide evidence that the amputation of the handed chela will result in a “handedness reversal,” and that the food type might influence the speed of the reversal. Crabs that were fed with fish blocks had a faster handedness reversal than those who were fed with commercial pellets feed, perhaps because of the increase in effort in individuals feeding on fish blocks.

The conserved role of juvenile hormone (JH) signals in preventing larvae from precocious metamorphosis has been confirmed in insects. Crustaceans have different metamorphosis types from insects; we previously proved that methyl farnesoate (MF) can prohibit larvae metamorphosis in mud crabs, but the molecular signal of this process still needs to be elucidated. In this study, methoprene-tolerant (Met) of Scylla paramamosain was obtained and characterized, which we named Sp-Met. Sp-Met contains a 3360 bp ORF that encodes 1119 amino acids; the predicted protein sequences of Sp-Met include one bHLH, two PAS domains, one PAC domain, and several long unusual Gln repeats at the C-terminal. AlphaFold2 was used to predict the 3D structure of Sp-Met and the JH binding domain of Met. Furthermore, the binding properties between Sp-Met and MF were analyzed using CD-DOCK2, revealing a putative high affinity between the receptor and ligand. In silico site-directed mutagenesis suggested that insect Mets may have evolved to exhibit a higher affinity for both MF or JH III compared to the Mets of crustaceans. In addition, we found that the expression of Sp-Met was significantly higher in female reproductive tissues than in males but lower in most of the other examined tissues. During larval development, the expression variation in Sp-Met and Sp-Kr-h1 was consistent with the immersion effect of MF. The most interesting finding is that knockdown of Sp-Met blocked the inhibitory effect of MF on metamorphosis in the fifth zoea stage and induced pre-metamorphosis phenotypes in the fourth zoea stage. The knockdown of Sp-Met significantly reduced the expression of Sp-Kr-h1 and two ecdysone signaling genes, Sp-EcR and Sp-E93. However, only the reduction in Sp-Kr-h1 could be rescued by MF treatment. In summary, this study provides the first evidence that MF inhibits crustacean larval metamorphosis through Met and that the MF-Met→Kr-h1 signal pathway is conserved in mud crabs. Additionally, the crosstalk between MF and ecdysteroid signaling may have evolved differently in mud crabs compared to insects.

The asymmetry trait in brachyuran crabs is mostly expressed by the different sizes or particular details of the two chelae. The causes for this asymmetry have been rarely investigated in the economically important crab Scylla paramamosain Estampador, 1950. We found that the asymmetric chelae first appeared in the megalopa stage. The examination of four "right-handed" and two "left-handed" mothers and their 521 megalopa offspring indicated that this trait might not be influenced by dominant alleles, since 86.0% -99.0% of megalopae exhibited the right-handed phenotype in the four offspring of the right-handed mother, whereas about 93.1% and 100% megalopae exhibited the right-handed phenotype in the two left-handed-mothers' offspring. The percentage of left-handed individuals at different stages also supports this hypothesis. We provide evidence that the amputation of the handed chela will result in a "handedness reversal," and that the food type might influence the speed of the reversal. Crabs that were fed with fish blocks had a faster handedness reversal than those who were fed with commercial pellets feed, perhaps because of the increase in effort in individuals feeding on fish blocks.

Background: 20-Hydroxyecdysone (20E) is the most ubiquitous ecdysteroid (Ecd) and plays critical roles during the life cycle of arthropods. To elucidate the metabolism pathway of 20E in the economically important species, Scylla paramamosain, we conducted a comprehensive exploration of the genes involved in the 20E metabolism pathway. Methods: A comprehensive exploration of genes involved in the 20E metabolism pathway was conducted, including gene annotation, local blast using the Drosophila ortholog as query, and TreeFam ortholog genes identification. Bioinformatics and expression profiling of the identified genes were performed to assess their roles in the 20E metabolism of green mud crabs. Results: This experiment indicated that, except for CYP306a1 and CYP314a1, all other ortholog genes involved in the Drosophila 20E metabolism can be found in the mud crab, suggesting that the function of these two genes might be replaced by other CYP genes or the “active” Ecd in mud crabs was not the 20E. All genes had the typical features of each gene family, clustered with the specific clade in the phylogenetic trees. In addition, all the identified genes had the highest expression level in the Y-organ, and sex-biased gene expression was observed in these genes. Conclusions: This study provided some valuable insights into the metabolism and diversity of ecdysteroids in crustaceans.

In open ocean environment with rich biodiversity, the assessment of fish resources is critical to the development of marine ecosystems and the sustainable use of resources. Environmental DNA (eDNA) metabarcoding is a new, constantly evolving tool and has recently been used to examine deep-sea eukaryotic diversity and communities. Here, eDNA metabarcoding was used to monitor fish populations in the central Pacific Ocean to understand the distribution of marine biodiversity in the region and investigate the abundance of dominant species. Water samples in present study were collected from three habitats, a total of 73 fish species from 41 families were detected, of which, 15 fish species from 10 families were found to be dominant species. What is more, the dominant species: Elagatis bipinnulata, Encrasicholina punctifer, Euthynnus affinis, lisha elongata, Nomeus gronovii, Reinhardtius hippoglossoides, Vinciguerria nimbaria had significant differences between habitats (p<0.05 or p<0.01). Alpha diversity indicated that the fish community composition in the three habitats was generally high, which was the highest at the Equator habitat. Beta diversity based on Bray–Curtis and Jaccard indices indicated that the fish composition of the three habitats overlapped in part, but there were not significantly different (p >0.05). Regression analyses indicated that there was an overall correlation in the biomass and reads richness (p <0.05) of Thunnus obesus and Katsuwonus pelami This study not only verities the validity and accuracy of eDNA technology applied to pelagic fish biodiversity assessment but also provides systematic cases for fish resource surveys in other sea areas and lays the foundation for oceanic fish resource monitoring.

The effects of calcined temperature on the properties and ozone decomposition activity of manganese oxide catalysts were investigated under high-humidity, low ozone conditions. An outstanding manganese-based catalyst (MnOx (260 ℃)) was prepared, which could decompose above 90% (RH = 0%) and 70% (RH = 90%) ozone after 6 h using. Specific characterization showed MnOx (260 ℃) had excellent properties. XRD results showed MnOx (260 ℃) was mainly Mn3O4 and partially MnO2. TEM indicated MnOx (260 ℃) exposed highly active crystal family plan MnO2 (110), and the lattice fringes of MnO2 (110) and Mn3O4 (103) overlapped. In situ DRIFT showed hydroxyl groups adsorbed on MnOx (260 ℃) were removed, which is beneficial to inhibiting the inactivation caused by surface water accumulation. O2-TPD results proven MnOx (260 ℃) had good oxygen migration ability. XPS results manifested that MnOx (260 ℃) had the most adsorbed oxygen. In short, when the calcination temperature is appropriate, MnOx (260 ℃) has coexisted multiple phases, exposed high active crystal family plan and removed surface hydroxyl, which is conducive to the exposure of oxygen vacancies and the inhibition of deactivation.

This study was the first to evaluate multiple hormonal manipulations to hepatopancreas over the ovarian development stages of the mud crab, Scylla paramamosain. A total of 1258 metabolites in 75 hepatopancreas explants from five female crabs were induced by juvenile hormone III (JH III), methyl farnesoate (MF), farnesoic acid (FA) and methoprene (Met), as identified from combined metabolomics and lipidomics (LC-MS/MS). 101 significant metabolites and 47 significant pathways were selected and compared for their comprehensive effects to ovarian maturation. While MF played an extensive role in lipid accumulation, JH III and Met shared similar effects, especially in the commonly and significantly elevated triglycerides and lysophospholipids (fold change≥2 and ≤0.5, VIP≥1). The significant upregulation of β-oxidation and key regulators in lipid degradation by FA (P ≤ 0.05) resulted in less lipid accumulation from this treatment, with a shift toward lipid export and energy consumption, unlike the effects of MF, JH III and Met. It was possible that MF and FA played their own unique roles and acted in synergy to modulate lipid metabolism during crab ovarian maturation. Our study yielded insights into the MF-related lipid metabolism in crustacean hepatopancreas for the overall regulation of ovarian maturation, and harbored the potential use of juvenoids to induce reproductive maturity of this economic crab species.

课程思政与思政课程在高等教育的育人过程中同等重要.本文对计量经济学课程思政建设问题进行了探讨,并结合课程特点、目前的教学现状以及课程思政建设的基础,提出了课程思政的建设思路,即通过课程思政案例的选择以及重要知识点的含义扩展两种方式来进行,同时也给出了课程思政的实施路径和实施方式,即兼顾课堂的理论教学与课后的上机实践,同时还要做到两种方式相互补充和相互配合.

In order to provide valuable guidelines for the conservation of germplasm of Lateolabrax maculatus , the genetic diversity and population structure analysis were evaluated for eight geographic populations along coastal regions of China, using 11 microsatellite DNA markers. The genetic parameters obtained showed that, eight populations can be clustered into two groups, the Northern group and the Southern group, concordant with their geographical positions. The UPGMA tree constructed according to the Nei’s genetic distance along with the structure analysis and discriminant analysis of principal component also supported this result. This might be explained by the geographic separation and the divergent environmental conditions among the populations. It's worth noting that, QD (Qingdao) population from northern area was assigned to the Southern group and showed a close genetic relationship and similar genetic constitution with the southern populations. We speculated that large scales of anthropogenic transportation of wild fries from QD populations to the southern aquaculture areas in history should be the primary cause. The populations from GY (Ganyu), RD (Rudong) and BH (Binhai) had higher genetic diversity and showed limited genetic exchange with other populations, indicating better conservation of the natural resources in these regions. All populations were indicated to have experienced bottleneck events in history.