LncRNA pol-lnc78 as a ceRNA regulates antibacterial responses via suppression of pol-miR-n199-3p-mediated SARM down-regulation in Paralichthys olivaceus

Long non-coding RNAs (lncRNAs) function as key modulators in mammalian immunity, particularly due to their involvement in lncRNA-mediated competitive endogenous RNA (ceRNA) crosstalk. Despite their recognized significance in mammals, research on lncRNAs in lower vertebrates remains limited. In the present study, we characterized the first immune-related lncRNA (pol-lnc78) in the teleost Japanese flounder ( Paralichthys olivaceus). Results indicated that pol-lnc78 acted as a ceRNA for pol-miR-n199-3p to target the sterile alpha and armadillo motif-containing protein (SARM), the fifth discovered member of the Toll/interleukin 1 (IL-1) receptor (TIR) adaptor family. This ceRNA network regulated the antibacterial responses of flounder via the Toll-like receptor (TLR) signaling pathway. Specifically, SARM acted as a negative regulator and exacerbated bacterial infection by inhibiting the expression of inflammatory cytokines IL-1β and tumor necrosis factor-α (TNF-α). Pol-miR-n199-3p reduced SARM expression by specifically interacting with the 3' untranslated region (UTR), thereby promoting SARM-dependent inflammatory cytokine expression and protecting the host against bacterial dissemination. Furthermore, pol-lnc78 sponged pol-miR-n199-3p to ameliorate the inhibition of SARM expression. During infection, the negative regulators pol-lnc78 and SARM were significantly down-regulated, while pol-miR-n199-3p was significantly up-regulated, thus favoring host antibacterial defense. These findings provide novel insights into the mechanisms underlying fish immunity and open new horizons to better understand ceRNA crosstalk in lower vertebrates.

[Analysis of 14 cases of melanosis caused by 1, 8-dinitronaphthalene and 1, 8-diaminonaphthalene]

14 workers in the 1, 8-diaminonaphthalene workshop of a chemical company in Nantong City had symptoms or signs of varying degrees of pruritus and pigmentation of the face, neck and waist. Pathological examination of skin biopsies showed hyperkeratosis, the basal cells were liquefied and denatured. Seven workers were eventually diagnosed with occupational melanosis. To explore the causes of occupational melanosis caused by exposure to 1, 8-dinitronaphthalene and 1, 8-diaminonaphthalene, and to provide reference for the prevention and treatment of occupational melanosis in the future, this paper reported 14 cases of melanosis in the skin of workers in chemical industry.

Development of stable Pickering emulsions/oil powders and Pickering HIPEs stabilized by gliadin/chitosan complex particles

In this paper, we demonstrate the use of gliadin/chitosan complex particles (GCCPs) as particulate stabilizers of oil-in-water emulsions of natural oils and water. For this purpose, we fabricated GCCPs through a facile anti-solvent procedure and demonstrated their usage in the formation of Pickering emulsions and Pickering high internal phase emulsions (HIPEs). The GCCPs can be used to produce surfactant-free o/w Pickering emulsions and Pickering HIPEs; unfortunately these emulsions were labile to coalescence. NaCl addition and/or pH regulation, and the combination were used to modify the surface wettability of the complex particles to achieve stable emulsions. The microstructures, e.g., interfacial frameworks, GCCP partition between the continuous phase and interfacial region, and the state of the droplets, of Pickering emulsions were visualized by confocal laser scanning microscopy (CLSM), confirming that the inclusion of NaCl and slightly adjusting pH toward 4.0 and/or 5.0 benefited the adsorption and accumulation of colloid particles at the droplet surface to form an engineered interfacial structure, bridging droplets together through a percolating layer of colloidal particles at the oil/water interface. A schematic representation for the formation route of the emulsions is proposed to relate the physical performance and rheological property with the interfacial structures and aggregate behaviors in the Pickering system stabilized by the complex particles. Interestingly, direct freeze-drying of the emulsions transformed unstable Pickering emulsions into stable oil powders. This study opens a promising route based on Pickering HIPEs or oil powders to structure liquid oils into solid-like fats without artificial trans-fat, which outlines new directions for future fundamental research.

Characterization and development of 56 EST-SSR markers derived from the transcriptome of Odontobutis potamophila

Expressed sequence tags (ETSs) are the sources of microsatellite development. In this study, we isolated and characterized microsatellite markers for Odontobutis potamophila by using Illumina RNA-sequencing. We sequenced a large number of ESTs and screened 200 potential microsatellites. Consequently, a total of 56 novel polymorphic microsatellite repeat markers were identified in thirty-two individuals from a wild population area (Jiande, Zhejiang Province, China). The number of alleles per locus varied from two to eight, the observed heterozygosity (H_O) ranged from 0.03571 to 0.9375, and the expected heterozygosity (H_E) ranged from 0.14326 to 0.81549. The average number of alleles, H_O, and H_E were 5.0, 0.4467, and 0.5518, respectively. By the calculation, the range of polymorphism information content (PIC) was 0.1177-0.8492. Most of the loci showed moderate or high polymorphism. These newly developed EST-simple sequence repeat (EST-SSR) markers would serve as an efficient tool for analyzing population connectivity and provide sufficient information for genetic diversity research, parentage, and molecular breeding of O. potamophila and other fishes with similar genetic relationship.

HcToll3 was involved in anti-Vibrio defense in freshwater pearl mussel, Hyriopsis cumingii

Toll-like receptors (TLRs) play an important role in the activation of innate immune response but their functions in bivalves remain largely unknown. In this study, we identified a TLR from the freshwater pearl mussel Hyriopsis cumingii (HcToll3) and investigated its functions in immunity. The full-length cDNA of HcToll3 is 3852 bp and includes an open reading frame (ORF) of 3228 bp that encodes a polypeptide of 1075 amino acids. The predicted HcToll3 protein shares similar structural characteristics with other known Toll family proteins. Quantitative real-time PCR analysis revealed that HcToll3 mRNA is broadly expressed in all of the examined tissues; its transcript level was significantly up-regulated by challenge with gram-negative bacteria Vibrio parahaemolyticus or lipopolysaccharide, but not gram-positive Staphylococcus aureus or peptidoglycan. RNA interference by siRNA results showed that HcToll3 regulated expression of whey acidic protein (HcWAP) and lysozymes (HcLyso1 and HcLyso2) in vivo and knockdown of HcToll3 suppressed the elimination of V. parahaemolyticus. These findings suggest that HcToll3 might be involved in anti-Vibrio defense in H. cumingii.

Phylogenetic relationships of twenty Gymnothorax species based on cytochrome b sequence data

To study the phylogenetic relationships of the genus Gymnothorax (moray eels) distributed in South China Sea, polymerase chain reactions were performed, and the amplification products were sequenced by cloning into the PMD18T-vector (TaKaRa). The entire gene sequences encoding cytochrome b (1140 bp) for 16 Gymnothorax (G. flavimarginatus, G. meleagris, G. undulates, G. reticularis, G. reevesi, G. melanospilus, G. rueppeliae, G. javanicus, G. chilospilus, G. pseudothyrsoideus, G. fimbriatus, G. hepaticus, G. berndti, G. curostus, G. favagineus, and G. margaritophorus) were obtained. Four additional Gymnothorax sequences from GenBank were also included. The nucleotide composition, genetic distances, and base substitution saturation analysis were calculated using the MEGA 5.0 Software. Phylogenetic analysis was performed using maximum-parsimony, maximum-likelihood (ML), and neighbor-joining (NJ). The results were as follows: 1) base-substitution saturation analysis suggested that both in third codon positions, and the full-length cytochrome b data set, Ts are not saturated, but Tv substitutions may be saturated, 2) the genus Gymnothorax, native to the South China Sea, is divided into four distinct clades, with two clades in the NJ and ML trees, and 3) according to our experimental data, G. melanospilus (Bleeker, 1855) and G. favagineus (Bloch and Schneider, 1801) are the same species.

Molecular cloning, characterization, and expression of vacuolar-type-H⁺-ATPase B1 (VHAB1) gene in the gill of Anguilla marmorata

We explored the molecular mechanism of the regulation of vacuolar-type-H+-ATPase B1 (VHAB1) in elvers in the response to salinity. The full-length cDNA of VHAB1 in Anguilla marmorata (designated as AmVHAB1), which was 1741 base pairs (bp) in length, was found to encompass a 1512-bp open reading frame encoding a polypeptide with 503 amino acids (55.9 kDa), an 83-bp 5'-untranslated region, and a 146-bp 3'-untranslated region. The mRNA and protein expression levels of AmVHAB1 in the gill were evaluated at different time points (0, 1, 3, 6, 12, 24, 48, 72, and 96 h, and 15 days) during the exposure to various salinity levels (0, 10, and 25‰). The results indicated that the expression levels of AmVHAB1 mRNA in the gill significantly increased and reached the highest level at 1 h exposure in the brackish water (BW, 10‰) group and at 6 h exposure in the seawater (SW, 25‰) group. The salinity level affected the relative expression level of AmVHAB1 mRNA in the gill, which was increased by approximately 44-fold in the SW group when compared with that in fresh water. Immunoblotting analysis showed that VHA expression was significantly higher in the BW and SW groups, with the highest expression level was detected at 96 h exposure. We found that the AmVHAB1 gene in elvers from A. marmorata plays an important role in the adaptation to seawater.

Development and validation of single nucleotide polymorphism markers in Odontobutis potamophila from transcriptomic sequencing

Transcriptome sequencing technology has been applied in the development and discovery of single nucleotide polymorphism (SNP) markers in fish. In this study, a panel of 120 expressed sequence tag (EST)-derived SNPs was selected by several selection filters from the resultant EST library of Odontobutis potamophila using Illumina Sequencing. In total, 37 SNPs from 120 putative SNPs were considered as the true SNPs using Sanger sequencing. For each SNP locus of 30 individuals of one wild population of O. potamophila that was successfully calculated, the number of alleles per locus was 2 with an observed heterozygosity of 0.0000-0.9000 and an expected heterozygosity of 0.1000-0.5263. A total of 33 loci conformed to Hardy-Weinberg equilibrium (HWE), and 4 loci deviated from HWE after Bonferroni correction. These 33 SNP markers will benefit the studies of population genetic structure, population evolution analysis, and construction of a high-density linkage map of O. potamophila.

Characterization of two novel ADP ribosylation factors from giant freshwater prawn Macrobrachium rosenbergii and their responses to WSSV challenge

ADP-ribosylation factors (Arfs) are small GTP-binding proteins that have an essential function in intracellular trafficking and organelle structure. To date, little information is available on the Arfs in the economically important giant freshwater prawn Macrobrachium rosenbergii and their relationship to viral infection. Here we identified two Arf genes from M. rosenbergii (MrArf1 and MrArf2) for the first time. Phylogenetic analysis showed that MrArf1, together with MjArf1 from shrimp Marsupenaeus japonicus belonged to Class I Arfs. By contrast, MrArf2 didn't not match any of the Arfs classes of I/II/III, although it could be clustered with an Arf protein from M. japonicas called MjArfn, which may represent an analog of the Arf. MrArf1 was ubiquitously expressed in all the examined tissues, with the highest transcription level in the hepatopancreas, whereas MrArf2 was only highly expressed in the hepatopancreas and exhibited very low levels in the heart, stomach, gills and intestine. The expression level of MrArf1 in the gills was down-regulated post 24 h WSSV challenge, and reached the maximal level at 48 h. MrArf1 in the hepatopancreas went up from 24 to 48 h WSSV challenge. MrArf2 transcript in the gill also went down at 24 h and then was upregulated at 48 h WSSV challenge. MrArf2 increased significantly in the hepatopancreas 24 h after infection and then went down at 48 h WSSV challenge. RNAi results showed that knockdown of MrArf1 or MrArf2 could inhibit the expression of the envelope protein gene vp28 of the WSSV. So, it could be speculated that MrArf1 and MrArf2 might play important roles in the innate immune system against WSSV infection.

Cloning and characterization of two different L-type lectin genes from the Chinese mitten crab Eriocheir sinensis

L-type lectins contain a leguminous lectin domain and bind to high-mannose type oligosaccharides. In the secretory pathway, L-type lectins play crucial functions in the trafficking, sorting, and targeting of maturing glycoproteins. This study identified two novel L-type lectins, designated as EsERGIC-53 and EsVIP36, from the Chinese mitten crab Eriocheir sinensis. The complete nucleotide sequence of ERGIC-53 cDNA was 1955 bp, containing a 1506 bp open reading frame (ORF) encoding a putative protein of 501 deduced amino acids. The full-length cDNA of VIP36 was 3474 bp with a 984 bp ORF encoding a 327-amino acid peptide. The deduced ERGIC-53 and VIP36 proteins contained a putative signal peptide and an L-type lectin-like domain. Phylogenetic analysis showed that ERGIC-53 and VIP36 belonged to different clades of L-type lectin family. Reverse transcription PCR showed that ERGIC-53 and VIP36 were expressed in all tested tissues. Quantitative real-time RT-PCR analysis revealed that ERGIC-53 and VIP36 transcripts in hepatopancreas were significantly induced at various time points after infection with lipopolysaccharide (LPS), peptidoglycan (PGN), Staphylococcus aureus, Vibrio parahaemolyticus, and Aeromonas hydrophila. A bacterium-binding experiment showed that both ERGIC-53 and VIP36 could bind to different microbes. Sugar binding assay revealed that these lectins could also bind to the glycoconjugates of bacteria surface, such as LPS, PGN, d-Mannose, and N-Acetyl-d-mannosamine. Moreover, these two L-type lectins agglutinated bacteria in a calcium-dependent manner, and both exerted the ability of facilitating the clearance of injected bacteria V. parahaemolyticus in the crab. Our results suggested that ERGIC-53 and VIP36 functioned as pattern recognition receptors in the immune system of E. sinensis.

Development and characterization of microsatellite loci in a threatened marine fish, Cheilinus undulatus (humphead wrasse)

Cheilinus undulatus (humphead wrasse) is a marine fish distributed widely throughout the tropical Indo-Pacific. It has been listed as vulnerable in the IUCN Red Data Book and in CITES Appendix II four times. Fifteen microsatellite loci were isolated and characterized for this species. The number of alleles ranged from 3 to 15 per locus, and the observed and expected heterozygosity ranged between 0.0323-0.7742 and 0.2597-0.8773, respectively. The polymorphism information content ranged from 0.2353-0.8520. Four microsatellite loci deviated significantly from Hardy-Weinberg expectations. No significant linkage disequilibrium was found among any of the loci. These microsatellite loci will be useful for future investigations of genetic variation in the wrasse population.

Isolation and characterization of 16 microsatellite loci in marble goby (Oxyeleotris marmoratus)

A microsatellite-enriched genomic library for marble goby (Oxyeleotris marmoratus), a freshwater fish of considerable economic value, was obtained. A total of 16 microsatellite markers were successfully isolated and characterized in a population from the Mekong River in Vietnam. These markers had 2-20 alleles with expected heterozygosity ranging from 0.0370 to 0.8927. Linkage equilibrium was observed in most loci, and only 1 locus revealed a significant deviation from Hardy-Weinberg equilibrium. These microsatellite markers will be useful for genetic diversity and molecular marker-assisted selection studies of wild and farmed O. marmoratus.

The first Toll receptor from the triangle-shell pearl mussel Hyriopsis cumingii

Toll receptor was first discovered in Drosophila and has an important function in the innate immunity of invertebrates. In this study, the Toll receptor HcToll1 from Hyriopsis cumingii with a full length of 3810 bp consisting of a 3687 bp ORF that encodes a total of 1228 amino acids protein was selected for further study. The HcToll1 protein consisted of a signal peptide, 17 LRR domains, 2 LRRCT domains, 1 LRRNT domain, 1 TM domain, and 1 TIR domain. Phylogenetic analysis results showed that HcToll1 was clustered in one group together with other mollusca tolls. RT-PCR analysis results showed that HcToll1 was expressed in all tested tissues such as hemocytes, hepatopancreas, gills, and mantle. qRT-PCR analysis results showed that HcToll1 expression was increased by the presence of Escherichia coli, Vibrio anguillarum, Staphyloccocus aureus, and White Spot Syndrome Virus (WSSV). Over-expression of HcTIR could up-regulate expression of drosomycin gene in Drosophila S2 cells. The results of our study indicated that HcToll1 is a functional Toll and it has an important function in the generation of innate immune responses of H. cumingii against microbial challenge.