Toxic effects of microplastics and nitrite exposure on intestinal histology, digestion, immunity, and microbial community of shrimp Litopenaeus vannamei.

Nitrite and microplastics (MPs) are environmental pollutants that threaten intestinal integrity and affect immune function of shrimp. In this study, the shrimp Litopenaeus vannamei were exposed to the individual and combined stress of nitrite and microplastics for 14 days, and the changes of intestinal histology and physiological functions were investigated. After single and combined stress, affectations occurred in intestinal tissue; the antioxidant enzyme activities (MDA, H2O2, CAT increased) and gene expression levels (CAT, SOD, GPx, HSP70 up-regulated) changed. The expression levels of detoxification genes (CYP450, UGT down-regulated, GST up-regulated), apoptosis genes (CASP-3 up-regulated) and endoplasmic reticulum stress genes (Bip, GRP94 down-regulated) changed. Furthermore, the stress also increased intestinal microbial diversity, causing bacterial composition variation, especially beneficial bacteria and pathogenic bacteria. These results suggested that nitrite and microplastics stress had adverse effects on the intestinal health of L. vannamei by affecting intestinal tissue morphology, immune response and microbial community.

Porous poly (lactic acid)/poly (ethylene glycol) blending membrane for microorganisms encapsulation.

ABSTRACTImmobilized microorganisms technology has been explored as a promising wastewater treatment method. To further increase the activity of the immobilized microorganisms, a porous membrane which was composed of poly (lactic acid) (PLA) and poly (ethylene glycol) (PEG) was designed for microorganism encapsulation. The plane membrane and the spherical membrane were prepared respectively. The morphology, mechanical properties, nitrate permeability, and biodegradability of the plane membranes were investigated to determine an optimized formulation. And then, denitrifying bacteria was encapsulated by the spherical membrane and its denitrification performance in synthetic wastewater was explored. The mean pore size of the PLA/PEG plane membranes ranged from 2.09 ± 0.63 µm to 3.15 ± 1.32 µm. PEG stimulated interconnected pore structure of the PLA/PEG plane membrane. Compare with neat PLA membrane, the tensile strength of the PLA/50%PEG plane membrane decreased by about 53.2% and elongation at break increased by about 103.5%. Nitrate permeability attained a maximum of 188.95 ± 4.59 mg·L-1·m-2·h-1 for PLA/50%PEG plane membrane. The denitrifying active sludge enclosed with the spherical membrane showed good denitrification performance in a short start-up time. The nitrate removal rate reached 51.14% on the 4th day and 82.53% on the 17th day. This porous PLA/50%PEG membrane was good for the diffusion of substrates and nutrients, which enabled the encapsulated microorganism recovered activity in a short time. The spraying method made the microorganism encapsulation could be designed according to the different microorganisms and different user environments, which expanded the application scope of microorganism encapsulation technology.

Integration of metagenomic and metabolomic insights into the effects of microcystin-LR on intestinal microbiota of Litopenaeus vannamei.

Microcystin-LR (MC-LR) is a hazardous substance that threaten the health of aquatic animals. Intestinal microbes and their metabolites can interact with hosts to influence physiological homeostasis. In this study, the shrimp Litopenaeus vannamei were exposed to 1.0 µg/l MC-LR for 72 h, and the toxic effects of MC-LR on the intestinal microbial metagenomic and metabolomic responses of the shrimp were investigated. The results showed that MC-LR stress altered the gene functions of intestinal microbial, including ABC transporter, sulfur metabolism and riboflavin (VB2) metabolism, and induced a significant increase of eight carbohydrate metabolism enzymes. Alternatively, intestinal metabolic phenotypes were also altered, especially ABC transporters, protein digestion and absorption, and the biosynthesis and metabolism of amino acid. Furthermore, based on the integration of intestinal microbial metagenomic and metabolome, four bacteria species (Demequina globuliformis, Demequina sp. NBRC 110055, Sphingomonas taxi and Sphingomonas sp. RIT328) and three metabolites (yangonin, α-hederin and soyasaponin ii) biomarkers were identified. Overall, our study provides new insights into the effects of MC-LR on the intestinal microbial functions of L. vannamei.

Essential oil of Magnolia denudata is an effective anesthetic for spotted seabass (Lateolabrax maculatus): a test of its effect on blood biochemistry, physiology, and gill morphology.

Magnolia denudata is a well-known ornamental tree in China due to its beautiful blossoms, and it has been used as an analgesic to treat human headaches. This study investigated the anesthetic potential and physiological response of the essential oil of M. denudata flowers on spotted seabass Lateolabrax maculatus. Fish (mean ± SD, 164.16 ± 15.40 g) were individually exposed to different concentrations of M. denudata essential oil (MDO, 10, 20, 40, 60, 80, 100, and 120 mg/L) and eugenol (10, 20, 30, 40, 50, 60, and 70 mg/L) to investigate anesthetic efficacy. Based on the ideal time criterion for anesthetic induction (< 3 min) and recovery (< 10 min), the lowest effective concentration for spotted seabass was 100 mg/L for MDO and 60 mg/L for eugenol. The physiological and histopathological damage in the gill of L. maculatus after using MDO and eugenol was also evaluated at the minimum dose inducing deep anesthesia, and at 0, 6, and 24 h after recovery. The results showed that MDO and eugenol anesthesia alleviated the levels of cortisol and glucose and the lactic dehydrogenase activity induced by handling. Compared with eugenol, MDO also caused secondary stress to the body, but MDO caused minor physiological responses and histological changes in the gills. This study suggests that MDO is an effective anesthetic for spotted seabass.

Responses of lipid metabolism and lipidomics in the hepatopancreas of Pacific white shrimp Litopenaeus vannamei to microcystin-LR exposure.

Microcystin-LR (MC-LR) is a toxic substance that threatens the health of aquatic animals. Hepatopancreas is the target organ of MC-LR toxicity. In this study, we investigated the effects of MC-LR on hepatopancreas lipid metabolism and lipidomic responses in Litopenaeus vannamei. After MC-LR exposure for 72 h, the hepatopancreas showed obvious tissue damage, and the activities of several lipase isoenzymes were decreased. Furthermore, the relative gene expression levels of lipolysis (CPT1, AMPKα), lipogenesis (SREBP, FAS, ACC, 6PGD), and long-chain fatty acid ß-oxidation (ACDL, ACDVL, ACBP) were increased. MC-LR exposure also affected lipidomics homeostasis. Specifically, the levels of glycerophospholipids (phosphatidylcholine, phosphatidic acid, lyso-phosphatidylcholine, lyso-phosphatidylethanolamine, lyso-phosphatidylglycerol), sphingolipids (sphingomyelin and ceramides) and cholesteryl ester were increased, and those of phosphatidylinositol and triglyceride were decreased. The significantly altered lipid molecules were mainly associated with the pathways of lipid and fatty acid metabolism and autophagy. These results reveal that MC-LR exposure influences lipid metabolism and lipidomic homeostasis in the shrimp hepatopancreas.

Mucoadhesive phenylboronic acid conjugated chitosan oligosaccharide-vitamin E copolymer for topical ocular delivery of voriconazole: Synthesis, in vitro/vivo evaluation, and mechanism.

Topical eye drops still face challenges of low-drug treatment effects and frequent dosing in ophthalmic applications due to the low preocular retention rate and low transcorneal permeability. Thus, we designed and synthesized a phenylboronic acid conjugated chitosan oligosaccharide-vitamin E copolymer (PBA-CS-VE) for use in mucoadhesive voriconazole (VRC)-loaded nanomicelles for fungal keratitis. In vitro mucin binding and ex vivo eyeball adhesion tests show that the copolymer has strong mucoadhesion. The transportation of coumarin-6 (C6) across a monolayer of HCE-T cells and 3D cell spheroids confirm the strong corneal penetration ability of PBA-CS-VE. The mechanism of promoting corneal penetration was studied in terms of intracellular calcium-ion concentration, cell membrane potential, cell membrane fluidity, and the tight junctions of cells. The pharmacokinetics in the aqueous humor were examined to evaluate the ability of nanomicelles in promoting corneal penetration and prolonging ocular retention. VRC-loaded PBA-CS-VE nanomicelles (PBA-CS-VE-VRC) yielded a very favorable therapeutic effect on a rabbit model of fungal keratitis in vivo as compared to the free drug. Overall, the results indicate that PBA-CS-VE nanomicelles are a mucoadhesive candidate with enhanced transcorneal permeability and prolonged preocular retention for efficient delivery of topical ocular drugs. STATEMENT OF SIGNIFICANCE: Although eye drops are widely used in ocular drug delivery, the disadvantages such as short retention time and weak corneal penetrating ability still seriously affect the therapeutic effect of the drug. Therefore, the mucoadhesive carrier seems to be an interesting strategy for ocular drug delivery. Herein, a novel phenylboronic acid conjugated chitosan oligosaccharide-vitamin E copolymer was designed and constructed as mucoadhesive nanomicelles loaded with voriconazole for fungal keratitis. These nanomicelles were able to improve the in vitro mucin binding and to prolong the residence time of the drug on the surface of the eyeball. Moreover, the nanomicelles exhibited an enhanced drug permeability in cell monolayer models and 3D cell culture models. This work provides a promising ocular drug delivery system.

Chronic Ethanol Exposure Enhances Facial Stimulation-Evoked Mossy Fiber-Granule Cell Synaptic Transmission via GluN2A Receptors in the Mouse Cerebellar Cortex.

Sensory information is transferred to the cerebellar cortex via the mossy fiber-granule cell (MF-GC) pathway, which participates in motor coordination and motor learning. We previously reported that chronic ethanol exposure from adolescence facilitated the sensory-evoked molecular layer interneuron-Purkinje cell synaptic transmission in adult mice in vivo. Herein, we investigated the effect of chronic ethanol exposure from adolescence on facial stimulation-evoked MF-GC synaptic transmission in the adult mouse cerebellar cortex using electrophysiological recording techniques and pharmacological methods. Chronic ethanol exposure from adolescence induced an enhancement of facial stimulation-evoked MF-GC synaptic transmission in the cerebellar cortex of adult mice. The application of an N-methyl-D-aspartate receptor (NMDAR) antagonist, D-APV (250 µM), induced stronger depression of facial stimulation-evoked MF-GC synaptic transmission in chronic ethanol-exposed mice compared with that in control mice. Chronic ethanol exposure-induced facilitation of facial stimulation evoked by MF-GC synaptic transmission was abolished by a selective GluN2A antagonist, PEAQX (10 µM), but was unaffected by the application of a selective GluN2B antagonist, TCN-237 (10 µM), or a type 1 metabotropic glutamate receptor blocker, JNJ16259685 (10 µM). These results indicate that chronic ethanol exposure from adolescence enhances facial stimulation-evoked MF-GC synaptic transmission via GluN2A, which suggests that chronic ethanol exposure from adolescence impairs the high-fidelity transmission capability of sensory information in the cerebellar cortex by enhancing the NMDAR-mediated components of MF-GC synaptic transmission in adult mice in vivo.

Unveiling sugarcane defense response to Mythimna separata herbivory by a combination of transcriptome and metabolic analyses.

BACKGROUND: Sugarcane is the most important sugar crop in the world. Like other crops, sugarcane suffers from herbivorous insect attack. The oriental armyworm Mythimna separata is a devastating pest of various crops in northeast Asia and an outbreak of this pest can result in substantial yield loss for sugarcane. However, the plant defense response situation is widely acquisition in model crops, but there is little information about how sugarcane plants defend themselves against this herbivore at the molecular and biochemical levels. RESULTS: We combined transcriptome and metabolomic analysis to investigate the changes in gene expression and metabolic processes that occurred in sugarcane plants after continuous feeding by M. separata larvae for 12 and 24 h. We identified 13 662 genes and 55 metabolites that were differentially regulated in sugarcane plants fed on by M. separata. The genes involved in phytohormones, transcription factors, and kinase-related were activated and metabolism compounds such as carbohydrate, amino acid, ferulic substances and glutathione were detected regulated in sugarcane defense response. Comparable analyses showed a close correspondence relationship among pathways of phenylalanine metabolism, phenylpropanoid biosynthesis, and flavonoid biosynthesis in transcript and metabolite profiles. Furthermore, a bioassay experiment was conducted to test the influence of up-regulated metabolites on M. separata growth and found chlorogenic acid had a lethal effect. CONCLUSION: The results of our study greatly enhanced the understanding of the sugarcane-induced defense response mechanism against herbivore infestation at the transcriptional and metabolic levels. Also make contributions to provide clues for development of green pest control method. © 2021 Society of Chemical Industry.

Toxic effects of cadmium and lead exposure on intestinal histology, oxidative stress response, and microbial community of Pacific white shrimp Litopenaeus vannamei.

Cadmium (Cd) and lead (Pb) are two hazardous pollutants that threaten shrimp farming. The intestine is an important organ for digestion and immunity. We separately exposed Pacific white shrimp Litopenaeus vannamei to 500 µg/L Cd or 500 µg/L Pb seawater for 7 days, and 45 shrimp from each group were used to evaluate the changes of intestinal histopathological, oxidative stress, and microbiota composition. After Cd and Pb exposure, shrimp intestine appeared significant mucosal damage and oxidative stress, and the microbiota variation were induced. Specifically, the abundance of the phyla Bacteroidetes and Actinobacteria were induced, that of Proteobacteria and Firmicutes were deduced. The abundances of putative beneficial bacteria (Lactobacillus, Weissella, Demequina, Formosa and Ruegeria) and potentially pathogenic bacteria (Vibrio and Photobacterium) were fluctuated. Furthermore, the nutrient metabolic function of intestinal microbes was significantly altered. We concluded that Cd and Pb exposure had negative effects on the intestinal health of shrimp.

Porous solid carbon source-supported denitrification in simulated mariculture wastewater.

A porous solid carbon source was prepared by semen litchi (SL), poly(vinyl alcohol) (PVA) and sodium alginate (SA) in aqueous. The effect of SL content on the structures and denitrification performance of the porous solid carbon source in simulated mariculture wastewater was investigated. The SL/PVA/SA beads showed a network structure with a wide range of macropores. Compared with blank beads, the SL/PVA/SA beads showed an increased rough surface and whole distribution on the surface with the increase of SL. In addition, SL/PVA/SA beads have more uniform pore size, but the porosity of SL/PVA/SA beads was decreased with the increase of SL. The porosity of the beads was 83.24%, 74.24%, 71.48% and 71.29% for blank beads and SL/PVA/SA beads contained 30%, 40% and 50% SL, when it was used as a solid carbon source for denitrification. Owing to their good porosity and biocompatibility, SL/PVA/SA beads had shorter acclimation time. Nitrate removal rate could reach up to 100% after two days of adaptation. After the exhaustion of carbon sources, nitrate removal rate less than 50% occurred at the 9th, 10th and 11th day for SL/PVA/SA beads that contained 30%, 40% and 50% SL, respectively. The beads that contained 50% SL exhibited longer lifetime during the denitrification reaction and denitrification rate could reach 243.5 ± 7.08 mg N (L d)-1. It could be used as an economical and effective carbon source for denitrification in mariculture wastewater.

Toxic effects of ammonia and thermal stress on the intestinal microbiota and transcriptomic and metabolomic responses of Litopenaeus vannamei.

Ammonia and thermal stress frequently have harmful effects on aquatic animals. The intestine is an important barrier allowing the body to defend against stress. In this study, we investigated the intestinal microbiota and transcriptomic and metabolomic responses of Litopenaeus vannamei subjected to individual and combined ammonia and thermal stress. The results showed that obvious variation in the intestinal microbiota was observed after stress exposure, with increased levels of Firmicutes and decreased levels of Bacteroidetes and Planctomycetes. Several genera of putatively beneficial bacteria (Demequina, Weissella and Bacteroides) were abundant, while Formosa, Kriegella, Ruegeria, Rhodopirellula and Lutimonas were decreased; pathogenic bacteria of the genus Vibrio were increased under individual stress but decreased under combined stress. The intestinal transcriptome revealed several immune-related differentially expressed genes associated with the peritrophic membrane and antimicrobial processes in contrasting accessions. Haemolymph metabolomic analysis showed that stress exposure disturbed the metabolic processes of the shrimp, especially amino acid metabolism. This study provides insight into the underlying mechanisms associated with the intestinal microbiota, immunity and metabolism of L.vannamei in response to ammonia and thermal stress; ten stress-related metabolite markers were identified, including L-lactic acid, gulonic acid, docosahexaenoic acid, l-lysine, gamma-aminobutyric acid, methylmalonic acid, trans-cinnamate, N-acetylserotonin, adenine, and dihydrouracil.

Toxicological effects of microplastics in Litopenaeus vannamei as indicated by an integrated microbiome, proteomic and metabolomic approach.

Microplastics (MPs) are a hazardous pollutant of world concern that threaten aquatic organisms and ecosystems. In this study, we chose the worldwide-distributed shrimp Litopenaeus vannamei as a model and investigated the toxicological effects of five types of MPs on L. vannamei using several omics approaches. After 14 days of exposure to MPs, obvious intestinal microbiota variation was observed, such as increased abundances of Bacteroidetes and Proteobacteria and a decreased abundance of Firmicutes. Specifically, MPs induced several putative opportunistic pathogens and reduced lactic acid- and short-chain fatty acid-producing bacteria. Alternatively, MPs altered haemolymph proteome profiles, but the five types of MPs had different effects on the enriched pathways and the expression of immune-related proteins. Furthermore, MPs also caused haemolymph metabolite variation, especially in amino acid and alpha-linolenic acid metabolism, and 28 differential metabolites were altered in the five MP-treated groups. Changes in intestinal bacteria were correlated with the haemolymph proteins and metabolites of the shrimp. Overall, these results reveal the toxicological effects of MPs on the intestinal microbiota and the host's immunity and metabolism in shrimp.

Characterization of field-evolved resistance to pyridalyl in a near-isogenic line of diamondback moth, Plutella xylostella.

BACKGROUND: Plutella xylostella has developed resistance to a variety of pesticides in the field. Selection, inheritance, a near-isogenic line, cross-resistance and biochemical mechanisms of pyridalyl resistance were characterized in a field-collected resistant population of P. xylostella from China. RESULTS: Compared with a susceptible IVF-S strain, the field-collected FZ population showed ~ 350-fold resistance to pyridalyl. The FZ-PY strain, selected from the FZ population using pyridalyl, developed ~ 640-fold resistance to pyridalyl. Inheritance tests indicated that pyridalyl resistance in the FZ-PY strain was autosomal and incompletely recessive. Through successive backcrossing to IVF-S, a near-isogenic strain (NIL-PY) was established that exhibited 191.21-fold resistance to pyridalyl and no cross-resistance to other tested popular insecticides. No significant effects of synergists and higher activities of metabolic enzymes were observed in NIL-PY compared with IVF-S. Furthermore, the survival rate of NIL-PY larvae, and female oviposition, fecundity and egg viability were markedly reduced in NIL-PY compared with IVF-S. The fitness of NIL-PY was found to be 0.56 compared with IVF-S. CONCLUSION: Considering that no relevant effects of synergists or oxidative metabolism were observed in NIL-PY, and that pyridalyl resistance results in significant fitness costs compared with IVF-S, further research will be conducted on the mechanism of target-site resistance. © 2020 Society of Chemical Industry.

Correction to: The effect of teprenone on the intestinal morphology and microbial community of Chinese sea bass (Lateolabrax maculatus) under intermittent hypoxic stress.

In the end of the Discussion section, following information should be included.

Characterization of flupyradifurone resistance in the whitefly Bemisia tabaci Mediterranean (Q biotype).

BACKGROUND: Bemisia tabaci is one of most notorious pests on various crops worldwide and many populations show high resistance to different types of insecticides. Flupyradifurone is a novel insecticide against sucking pests. B. tabaci resistance to flupyradifurone has been detected in the field, however the mechanism of flupyradifurone resistance has rarely been studied. RESULTS: The flupyradifurone-resistant strain (FLU-SEL) was selected from the susceptible strain of B. tabaci (MED-S) using flupyradifurone for 24 generations. The FLU-SEL strain exhibited 105.56-fold resistance to flupyradifurone, and moderate cross-resistance to imidacloprid, but no cross-resistance to other tested neonicotinoids. Synergism tests and metabolic enzyme assays suggested that FLU-SEL resistance can be attributed to enhanced detoxification mediated by glutathione S-transferase (GST) and P450 monooxygenase (P450). Compared with MED-S strain, CYP6CX4 and GSTs2 were significantly overexpressed in FLU-SEL, and silencing CYP6CX4 or GSTs2 increased the mortality of whiteflies to flupyradifurone challenge in FLU-SEL. In addition, silencing CYP6CX4 also increased the mortality of whiteflies exposed to imidacloprid. CONCLUSION: Overexpression of CYP6CX4 and GSTs2 was associated with flupyradifurone resistance, as confirmed by RNA interference. Our findings suggested that metabolic resistance to flupyradifurone might be mediated by P450s and GSTs. © 2020 Society of Chemical Industry.

Changes in the microbial community of Litopenaeus vannamei larvae and rearing water during different growth stages after disinfection treatment of hatchery water.

Microbial communities greatly affect rearing water quality and the larvae health during shrimp hatchery periods. In this study, we investigated the microbial communities of rearing water and larvae of Litopenaeus vannamei after treating hatchery water with different kinds of chemical disinfectants: no disinfectants (Con), chlorine dioxide (ClO2), formaldehyde solution (HCHO), bleach powder (CaClO), and iodine (I2). The water and larval samples were collected from nauplius 6 (N6), zoea 1 (Z1), mysis 1 (M1), and postlarvae 1 (P1) shrimp growth periods. 16S rDNA high-throughput sequencing revealed that the bacterial composition of the rearing water was more complex than that of the larvae, and the bacterial community of the rearing water and the larvae fluctuated significantly at the P1 and Z1 periods, respectively. Disinfectants altered the bacterial diversity and composition of the rearing water and larvae. Specifically, in the rearing water of the P1 period, Proteobacteria abundance was increased in the HCHO group; while Bacteroidetes abundance was decreased in the ClO2, HCHO, and I2 groups but increased in the CaClO group. In the larvae of the Z1 period, Firmicutes (especially Bacillus class) abundance was increased in the CaClO group, but decreased in the ClO2, HCHO, and I2 groups. Network analyses revealed that the genera Donghicola, Roseibacterium, Candidatus-Cquiluna, and Nautella were enriched in the rearing water, while Halomonas, Vibrio, and Flavirhabdus had high abundance in the larvae. The survival of shrimp was influenced by disinfectants that were inconsistent with the bacterial community changes. These results will be helpful for using microbial characteristics to facilitate healthy shrimp nursery.

The effect of teprenone on the intestinal morphology and microbial community of Chinese sea bass (Lateolabrax maculatus) under intermittent hypoxic stress.

Hypoxia stress may affect the fish intestine and thereby threaten the growth and survival of the fish. Teprenone is a clinically effective agent in protecting gastrointestinal mucosa. This study aims to assess the effect of teprenone in the intestine of Chinese sea bass Lateolabrax maculatus under intermittent hypoxic stress. L. maculatus juveniles were either raised under intermittent hypoxic condition or normal condition (NC). Part of the hypoxic-intervened fish were treated with teprenone at different concentrations (HTs), and the rest were regarded as hypoxic control (HC). Histological analysis was performed on the epithelial tissue of the fish intestine. High-throughput sequencing technology was used to analyze the diversity and composition of the microbial community in L. maculatus intestine. Reduced villi length and goblet cell, exfoliated enterocyte, and improper arrangement of villi were observed in HC compared with NC and HTs. Proteobacteria, Firmicutes, and Bacteroidetes represented the most abundant phyla in each sample. Significantly higher microbial diversity was detected in HC compared with NC (P < 0.05). At the phylum level, HC presented significantly decreased relative abundance of Proteobacteria, and significantly increased relative abundance of Bacteroidetes, Chloroflex, and Cyanobacteria compared with NC (P < 0.05). At the class level, HC showed significantly reduced relative abundance of Alphaproteobacteria and Bacilli, and significantly increased relative abundance of Clostridia, Gammaproteobacteria, and Bacteroides (P < 0.05). Teprenone protects the intestine from epithelial damages and maintains the microbial harmony in L. maculatus under intermittent hypoxic stress.

Effects of Microcystis aeruginosa and microcystin-LR on intestinal histology, immune response, and microbial community in Litopenaeus vannamei.

Microcystis aeruginosa (MA) is a primary hazardous cyanobacteria species in aquatic ecosystems that can produce microcystin-LR (MC-LR), which harms aquatic animals. The intestine is an important target tissue for MA and MC-LR. In this study, we investigated the effects of MA and MC-LR exposure on the intestinal microbiota variation and immune responses of Litopenaeus vannamei. Shrimp were experimentally exposed to MA and MC-LR for 72 h. The results showed that both MA and MC-LR exposure caused marked histological variation and apoptosis characteristics and increased oxidative stress in the intestine. Furthermore, the relative expression levels of antimicrobial peptide genes (ALF, Crus, Pen-3) decreased, while those of pro-inflammatory cytokines (MyD88, Rel, TNF-a), a pattern-recognition receptor (TLR4) and a mediator of apoptosis (Casp-3) increased. MA and MC-LR exposure also caused intestinal microbiota variation, including decreasing microbial diversity and disturbing microbial composition. Specifically, the relative abundance of Proteobacteria decreased in the two stress groups; that of Bacteroidetes decreased in the MA group but increased in the MC-LR group, while Tenericutes varied inversely with Bacteroidetes. Our results indicate that MA and MC-LR exposure causes intestinal histopathological and microbiota variations and induces oxidative stress and immune responses in L. vannamei. In conclusion, this study reveals the negative effects of MA and MC-LR on the intestinal health of shrimp, which should be considered in aquaculture.

Transcriptomic analysis of juvenile Chinese sea bass (Lateolabrax maculatus) anesthetized by MS-222 (tricaine methanesulfonate) and eugenol.

MS-222 (tricaine methanesulfonate) and eugenol are the two frequently used fish anesthetics. This study intends to analyze the regulation of these anesthetics in Chinese sea bass, Lateolabrax maculatus, through transcriptomic analysis. L. maculatus were exposed to MS-222 or eugenol, and those without any treatments were regarded as controls. Gills and livers were extracted for transcriptomic analysis after recovery in fresh water for 6 h. Identified genes were assigned to NR, COG, SWISS, GO, and KEGG database for predicting gene functions. A FDR ≤ 0.05 and |log2(FC)| ≥ 1 were applied to determined differentially expressed gene (DEG). A total of 45,626 unigenes were annotated using at least one database. The eugenol-treated liver group presented less DEGs compared with that treated by MS-222. Both the MS-222- and eugenol-treated liver groups presented notable DEGs that participated in human disease and metabolism pathways. The eugenol group showed more pathways related to detoxification activity and xenobiotics biodegradation, and those from the MS-222 group were related to organismal system such as reproduction. By comparing gill and liver samples using the same drug, the enriched pathways were generally consistent among the three comparisons. In conclusion, eugenol and MS-222 could change the pathways related to metabolism and immunity in L. maculatus. MS-222 may trigger more damages on the fish liver and reproduction.

Protection of teprenone against hypoxia and reoxygenation stress in stomach and intestine of Lateolabrax maculatus.

Teprenone (geranylgeranylacetone) is one kind of safe and effective agent in gastrointestinal mucosa, which have been widely used in human and veterinary, but rarely used in aquaculture animals. In this study, Lateolabrax maculatus, an important economic fish species in southern China, was taken as the object of study to investigate the protective effect of teprenone on intestinal stress. The present study was designed to investigate the potential mechanism underlying the protection offered by teprenone to protect the gastrointestinal tract against hypoxia and reoxygenation injury of L. maculatus. (a) For oxidative stress parameters, SOD, CAT, and T-AOC in control group were higher than those in teprenone group. MDA content was significantly higher than that in teprenone group at N and 12h time points in intestine (P < 0.05), and at 12, 24, and 48 h time points in stomach. (b) For immune-associated proteins, LZM activity in the control group was lower than that in the teprenone group, and the difference between the two groups in stomach and intestine was significant at 12.48 h and 6.48 h time points, respectively (P < 0.05). Compared with time point N, the content of HSP70 in the control group increased at 0 h in intestine. At 0-48 h, intestine HSP70 content in the control group showed a gradually decreasing trend, which was higher than that in the teprenone group. (c) For apoptosis-related factors, the activity of Cyt-C, caspase9, and caspase3 increased first and then decreased in both groups. The content of Cyt-C in the control group was significantly higher than that in the teprenone group at N-3.6 h, and 3.48 h time points in stomach and intestine, respectively (P<0.05). The activity of caspase9 and caspase3 was higher than that in the teprenone group at N-48 h. Results indicated that acute hypoxia and reoxygenation cause the expression levels of oxidative stress and apoptosis-related factors in the stomach and intestine increased first and then decreased within 0-48 h. Acute hypoxia and reoxygenation also that causes the level of nonspecific immunity decreased first and then increased. A total of 400-mg/kg treatment of teprenone can protect stomach and intestinal tissues to a certain extent. It can effectively protect oxidative stress and apoptosis within 0-48 h after acute hypoxia and reoxygenation and enhance non-specific immunity.