Intestine Of Fish Research Articles

Trace metal accumulation is infrapopulation-dependent in acanthocephalans parasites of the white mullet (Mugil curema) from an estuarine environment of southeastern Brazil coast

Here, in an estuarine canal in southeast Brazil, we evaluated the potential for trace metal accumulation of the acanthocephalan parasite Floridosentis mugilis, which infects the fish host Mugil curema. The quantities of the trace metals were quantified using Inductively Coupled Plasma Mass Spectrometry (ICP-MS), which was used to analyze samples of the fish's muscle, intestine, and liver as well as the parasites. The parasites and the host's tissues had significantly different trace metal concentrations, according to our data. Furthermore, some metals have quite high bioconcentration factors, including Al, Cr, Ni, and Cd. We also found that the trace metal concentrations in the parasites were impacted by the sizes of the parasitic infrapopulations, with smaller infrapopulations tending to accumulate more metals. This study shows this acanthocephalan species' effective ability to store metals and is the first to investigate metal accumulation using it as a model.

Species-specific effects of microplastics on juvenile fishes.

Microplastics contamination have been extensively reported in aquatic ecosystem and organisms. It is wildly acknowledged that the ingestion, accumulation and elimination of microplastics in fishes are species-specific, which mainly depending on the feeding behavior. This study aimed to investigate the effects of microplastics on the morphology and inflammatory response in intestines of fishes with different feeding types. Largemouth bass (carnivorous fish), grass carp (herbivorous fish) and Jian carp (omnivorous fish) were used as organism model. The contributing concentration and size of microplastics were explored as well as the response time and legacy effect in fishes. Two different sizes of polystyrene microplastics (80nm and 8μm) were set at three concentrations. And samples were analyzed at different exposure times and depuration times. Histological analysis indicated that multiple abnormalities in intestines were presented in three species fishes after acute exposure microplastics. The mRNA abundance of immune-related genes in the intestine tissues of fishes were significantly fluctuant. There were differential expressions of genes coping with differential sizes and concentrations of microplastics exposure in different fishes. The reason for the difference effects of microplastics on fishes was still unclear but could be due to the difference in the structure and function of the digestive system. These results provided a theoretical basis to further analysis of the mechanism of fish intestinal pathology caused by microplastics.

Detrimental influence of industrial effluents, especially heavy metals, on limnological parameters of water and nutritional profile in addition to enzymatic activities of fish, Sperata seenghala (Sykes, 1839) from diverse Ramsar sites, India (Punjab).

The present research was designed to determine the nutritive value of the liver and intestine of fish, Sperata seenghala, the impact of effluence load on limnological parameters of water and proximate composition of fish organs, especially on fatty acids, liver enzymatic activities, seasonal variations in the nutritional profile of fish, and to check and compare the pollution status of Ramsar sites in Punjab by calculating the water quality index, heavy metal pollution index, and metal index from June 2018 to August 2020. WQI of Harike wetland was found to be 53.95, which depicts that water quality in this region is "poor". At Nangal wetland, water quality index was reported to be "excellent" quality water and fit for the whole ecological unit. Overall heavy metal pollution index for Harike wetland was reported 174.569, whereas for Nangal wetland it was 5.994, depicting massive contaminant loads in a polluted region. MI value was also recorded as being higher (6.9336) in polluted habitat than in control habitat (0.8175). In fish liver, significant (p < 0.05) higher mean total lipids (6.73%), total proteins (3.98%), moisture (77.69%), ash (3.56%), and carbohydrates (3.79%) were observed in the samples from Nangal wetland than Harike wetland. A similar trend was reported in all biochemical contents of the fish intestine. Enzyme activities such as aspartate-aminotransferase and alanine-aminotransferase were significantly elevated (p < 0.05) in the specimens collected from the polluted region. The mean total n-3 (except in spring), n-6 polyunsaturated fatty acids (except in winter), and average monounsaturated and saturated fatty acids diminished significantly (p < 0.05) in the liver of fish from contaminated habitat than control site. In the intestine of fish collected from the polluted region, significant reductions in the mean total n-3 (except in autumn as well as summer), total n-6 PUFAs (in autumn and winter), and total SFAs were reported than control site.

Chrysene alters the expression pattern of HSP70 genes in mandarin fish

The heat shock protein 70 (HSP70) in fish plays a crucial role in various physiological and environmental stresses. To reveal the mechanisms of the HSP70 gene response to abiotic stress in mandarin fish (Siniperca chuatsi), we analyzed the HSP70 gene family in this species. There are 16 HSP70 genes in mandarin fish, and their protein three-dimensional structures were constructed. The aliphatic index of the 16 mandarin fish HSP70sranges from 73.50 (HSPa4b) to 99.46 (HSPa13), and all are hydrophilic proteins, with seven of them being unstable proteins. After exposure to chrysene, six HSP70 genes in the intestine, four in the liver, and four in the brain tissues exhibited significant expression changes. These findings reveal that chrysene exposure affects the physiological status of fish, and HSP70 genes may play a role in the chrysene exposure tolerance of the intestine, brain and liver in mandarin fish.

Isalo scorpion Cytotoxic peptide (IsCT) improved the physical barrier of the intestine on on-growing grass carp (Ctenopharyngodon idella)

Isalo scorpion cytotoxic peptide (IsCT) is an α-helical antimicrobial peptide with antibacterial and immunomodulatory activities. This research was performed to examine the link between Isalo scorpion cytotoxic peptide (IsCT) and the physical barrier of the intestine partially linked to antioxidant activity, apoptosis, and apical junction complex (AJC) of grass carp. Within sixty days, fish were arbitrarily divided into six treatments and fed six levels of IsCT (0, 0.6, 1.2, 1.8, 2.4, and 3.0 mg/kg diet), respectively. A six-day challenge test of Aeromonas hydrophila was subsequently performed. We found that appropriate IsCT supplementation (1.8 mg/kg diet) (1) reduced reactive oxygen species (ROS), protein carbonyl (PC) and malondialdehyde (MDA) contents, increased antioxidant enzyme activities and mRNA levels partly linked to regulation of the Kelch-like-ECH-associated protein (Keap)/NF-E2-related factor 2 (Nrf2) signaling in the intestines; (2) decreased DNA fragmentation and alleviated apoptosis partially associated with the intrinsic pathway [(Bcl-2, Mcl-1, and Bax)/Apaf-1/caspase-9/caspase-3] and the extrinsic pathway (FasL/caspase-8/caspase-3, −7) regulated by the c-Jun N-terminal kinase (JNK) [not p38 mitogen-activated protein kinase (p38 MAPK)] signaling pathway in fish intestines; (3) ameliorated intestinal AJC barrier partially linked to strengthening the tight junction (TJ) and adherents junction (AJ) integrity regulated by a small Rho GTPase protein (RhoA)/the Rho-associated protein kinase (ROCK) signaling pathway in fish intestines. However, the mRNA expression of glutathione-S-transferase P2 (GSTP2), p38 MAPK, claudin-7a, claudin-7b, and claudin-15b in the intestines of grass carp was unaffected by IsCT supplementation. Our research revealed that IsCT enhanced the physical barrier of fish intestines associated with maintaining intestinal epithelial cells (IECs) and apical junctional complex (AJC) integrity. Based on ROS and PC contents, the appropriate levels of IsCT in grass carp were determined to be 1.78 and 1.77 mg/kg diet, respectively.

Implications of Asparagus racemosus and Terminalia chebula extracts on oxazolone induced inflammatory bowel disease in Danio rerio (zebrafish)

Inflammatory Bowel Disease (IBD) occurs in the human intestine without any definitive etiology for which there is no cure yet. The present study analyses the anti-inflammatory and anti Inflammatory Bowel Disease (IBD) potentials of the methanol extract of Indian herbal plants Asparagus racemosus (AR) and Terminalia chebula (TC). First, we prepared methanolic extracts of AR root and TC fruit using the Soxhlet procedure and analyzed their phytochemical composition by GC-MS. Second, the extracts were used against Escherichia coli and Bacillus cereus cultures and observed for growth and biofilm inhibition. Third, the anti-oxidant assays were performed for the same extracts. Finally, we studied pathological and hematological analysis to study a reduction in the number of inflammatory cells following oxazolone-induced IBD in the zebrafish (Danio rerio). Both extracts contain steroids, terpenoids, tannins, phenols, and carbohydrates as active ingredients with moderate antibacterial activity against Escherichia coli and Bacillus cereus with minimum inhibitory concentration (MIC) of 12.5 μg/ml (TC) and 25 μg/ml (AR) against both bacteria. AR extract showed high biofilm inhibition on E. coli (80.8 ± 0.81%) and B. cereus (92.8 ± 1.08%) at 800 μg/mL and showed high DPPH radical scavenging activity IC50 value of 139.9 μg/mL. Further in IBD zebrafish, AR (14 mg/L) and TC (60 mg/L) exhibited a significant reduction in inflammatory cells in blood and improved pathological scores in the gut compared with positive drug Prednisolone (50 mg/L). Moreover, T. chebula showed a greater reduction in the number of inflammatory cells recruited in the intestine of IBD-induced fish compared to A. racemosus at the time point and dose examined.

An in-depth characterisation of European seabass intestinal segments for assessing the impact of an algae-based functional diet on intestinal health

Sustainable farming of fish species depends on emerging new feed ingredients, which can alter the features of the digestive tract and influence animals’ overall health. Recent research has shown that functional feeds hold great potential for enhancing fish robustness by evoking appropriate responses at the intestine level. However, there is a lack of extensive and accurate descriptions of the morphology of the gastrointestinal tract of most farmed fish. We have characterised the intestine of European seabass thoroughly, by targeting four segments − anterior, mid, posterior and rectum. Results indicated that the anterior segment is mostly associated with absorption-related features; this segment has the largest absorptive area, the longest villi, and the highest number of neutral goblet cells (GC). The posterior segment and rectum have distinct histomorphometric features, but both seem to be important for immunity, displaying the highest count of acid GC and the highest expression of immune-related genes. The strongest proliferating cell nuclear antigen (PCNA) signal was observed in the anterior intestine and rectum, with PCNA+ cells appearing at the base of the villi and the corresponding villi branches. We have also evaluated the impact of a novel feed supplemented with a macro- and microalgae blend and found that there were no differences in terms of growth. However, the alterations observed in the mid intestine of fish fed the blend, such as thickening of the submucosa and lamina propria, an increased number of leucocytes, and higher expression of immune- and oxidative stress-related genes, suggest that algae may have an immunomodulatory effect. In the current article, we have described the morphology and expression patterns of the intestine segments of European seabass in detail and have presented a comprehensive report of the indices and methods used for the semi-quantitative and quantitative histomorphometric assessments, thereby providing useful information for future studies that aim to maintain intestinal health through dietary interventions.

LncRNA activates immune response against Vibrio anguillarum in the intestine-liver axis of turbot (Scophthalmus maximus L.) by sponging miRNA in a ceRNA regulatory network

Vibriosis, most commonly caused by the bacterium Vibrio anguillarum, is one of the most important diseases affecting the marine aquaculture industry throughout the world. The intestine is the main entry portal of V. anguillarum into host fishes. Although there has been extensive research on the immunity of the gut-associated lymphoid tissue (GALT) in teleost, the mechanisms underlying the immunity of the intestine-liver during bacterial infections are still not well understood. This study conducted an integrative analysis of the transcriptome in turbot (Scopthalmus maximus L.) intestine and liver after V. anguillarum infection. To provide evidence of immunological collaboration in the turbot intestine-liver axis, we constructed the immune gene libraries, and conducted the functional annotation and enrichment analyses of immune genes that were jointly expressed in both turbot intestine and liver. Additionally, we administered the bioinformatic analyses of transcriptomic data to investigate regulatory relationships between non-coding RNAs (ncRNAs) and their target immune genes, based on the ceRNA theory. The recognition and binding abilities to bacteria were activated by the Toll-like receptor (TLR) signaling pathway. Subsequently, NF-κB was activated by the TLR/MyD88 signaling, and its target genes were induced to up-regulate in intestine and associated tissues to the digestive tract to enhance disease resistance through the production of inflammation. Histology of the intestine and liver of infected fish showed pathological changes consistent with inflammation. Bioinformatic analysis suggested that ceRNA regulatory networks play a pivotal role in the regulation of TLR genes, and RT-qPCR analyses and dual-luciferase reporter assays showed confirmed evidence to verify these hypothesized regulatory relationships. Overall, the results in this study demonstrated that a lncRNA (LNC_002468) activated the TLR signaling pathway by upregulating the TLR9 gene through sponging miRNA (novel_709). This study provides a strong indication that ncRNAs play regulatory roles in the antibacterial immune response of teleost fishes. However, further functional verification is required of the key immune genes and their regulatory relationship with miRNAs and lncRNAs.

Disruption of the intestinal barrier by avermectin in carp involves oxidative stress and apoptosis and leads to intestinal inflammation

Avermectin (AVM) is a widely used insecticide. Due to its sensitive toxicity to aquatic organisms, the toxicology of AVM on fish intestines remains unclear. Here, we established a 96 h AVM acute toxicity model to explore the effects of AVM on the intestinal tract of carp. The 96 h LC50 of carps exposed to AVM was 24.04 μg/L, 12.02 μg/L was selected as the high-dose group and 3.005 μg/L was selected as the low-dose group. After 96 h of exposure, intestinal tissues were collected and subsequently analyzed for histopathology, the activities of antioxidant oxidases (CAT, SOD, GSH-Px), and the expression of mRNA associated with oxidative stress, inflammation, and apoptosis. Our study showed that AVM exposure caused intestinal damage in carp, decreased the expression of the tight junction protein gene, activated oxidative stress, induced apoptosis, and induced intestinal inflammation in carp. Therefore, we demonstrated that AVM exposure compromised the integrity of the intestinal barrier in carp, activated oxidative stress, induced endogenous apoptosis, and induced intestinal inflammatory responses. These results indicate that AVM, as a drug-sensitive to aquatic organisms, has a much more complex toxic effect on the fish intestinal tract, which provides a new perspective for studying the toxicology of AVM on the fish intestinal tract.

Copper induced intestinal inflammation response through oxidative stress induced endoplasmic reticulum stress in Takifugu fasciatus

Copper (Cu) pollution in aquaculture water has seriously threatened the healthy and sustainable development of the aquaculture industry. Recently, many researchers have studied the toxic effects of Cu exposure on fish. However, the relationship between endoplasmic reticulum stress (ERS) and the inflammatory response, as well as its possible mechanisms, remain unclear. Particularly, information related to fish intestines must be expanded. Our study initially investigated the mechanisms underlying intestinal toxicity and inflammation resulting from Cu-induced ERS in vivo and in vitro in Takifugu fasciatus. In vivo study, T. fasciatus were treated with different concentrations (control, 20, and 100 µg/L) of Cu exposure for 28 days, causing intestinal oxidative stress, ERS, inflammatory responses, and histopathological and ultrastructural damage. Transcriptomic data further showed that Cu exposure caused ERS, as well as inflammatory responses, in the intestinal tracts of T. fasciatus. In vitro experiments on the intestinal cells of T. fasciatus showed that Cu exposure treatment (7.5 µg/mL) for 24 h induced ERS and increased mitochondrial numbers and inflammatory responses. In contrast, the addition of 4-phenylbutyric acid (4-PBA) alleviated ERS and inflammatory response in the Cu-exposed group. Furthermore, the reactive oxygen species (ROS) inhibitor, N-Acetyl-l-cysteine (NAC), effectively alleviated Cu-induced ERS. In conclusion, our in vivo and in vitro studies have confirmed that oxidative stress triggers the ERS pathway, which is involved in the intestinal inflammatory response. Our study provides new insights into the relationship among Cu-induced oxidative stress, ERS, and inflammatory responses in fish, as well as for the healthy culture of fish in aqueous environments.

Comparative Study of the Parasitic Helminth Burden of Clarias gariepinus and Tilapia zilli In Fresh Water Reservoir (Zobe Dam) Dutsin-Ma, Katsina, Nigeria

&#x0D; The incidence of gastrointestinal helminth parasites was investigated in a research of Clarias gariepinus and Tilapia zilli from Zobe Dam, Dutsin-ma. The results showed a high prevalence of helminth parasites overall, with T. zilli recording 36% and C. gariepinus showing a rate of 68%. Cestodes, trematodes, and nematodes were the three types of parasites found in the fish's intestines. Notably, trematodes predominated in T. zilli (54.55%), whereas cestodes were more common in C. gariepinus (62.71%). Procamallanus leavionchus was the most notable nematode species found in C. gariepinus, followed by cestodes (Polyonchobothrium clarias) and trematodes (Diplostomum spathaceum). The nematodes, cestodes, and trematodes in T. zilli were represented by Cacullanus sp., Diphyllobothrium spp., and Hepsetidae fasciatus, respectively. Both species showed that males had more helminth parasites than females did. In C. gariepinus, statistical analysis showed no gender differences, however in T. zilli, a gender difference was seen at the P&lt;0.05% level of significance. In addition, the study found a statistically significant correlation between fish length and body weight, and the frequency of helminth infections. These results highlight the significant load of helminth parasites in both Clarias gariepinus and Tilapia zilli, highlighting the need for efficient control techniques to reduce the negative effects of parasitic illnesses on fish production.

PENGUJIAN PENYAKIT KOMODITAS IKAN AIR TAWAR PADA LALU LINTAS DOMESTIK DI STASIUN KARANTINA IKAN JAMBI

Increased trade flows of international and domestic fishery coomodities in the opportunity to enter and spread Hama penyakit Ikan Karantina (HPIK) caused by pathogenic organism, namely bacteria, parasites, fungi, and viruses. This study aims to identify whether freshwater fish commodities in domestic traffic are infected with parasites, the bacteria Edwardsiella ictaluri, TiLV (Tilapia lake Virus) and the fungus Aphanomyces invadans at the Fish Quarantine Stasion, Quality Control and Safety of Fishery Products Jambi. Fish samples consist of 15 fish samples to be tranported. Based on results of the examinatoin of fish diseases, Parasite Examination there were 4 parasites with 3 types of parasites, namely 2 parasites of Dactylogyrus sp. On the gills of Tilapia and catfish. One (1) parasite Gyrodactylus sp. On fish slime Stripe 3, and 1 parasite Camallanus sp.in the intestines of betta fish; on bacterial examination of the 4 samples of fish examined, Edwardsiella ictaluri bacteria were nof found; on virus examination the result were negative for TiLV (Tilapia lake Virus); on examination of the fungus with the PCR method, negatif result were obtained for the fungus Aphanomyces invadans which is the cause of EUS (Epizootic Ulcerative Syndrome).

Phylogenetic assessment of some Palearctic Allocreadium spp. (Trematoda, Gorgoderoidea: Allocreadiidae).

The genus Allocreadium is a group of digenetic trematodes whose adult representatives mainly parasitize the intestines of freshwater fishes. The aim of this research is to reconstruct the phylogeny of four Palearctic species of this genus, Allocreadium dogieli, Allocreadium isoporum, Allocreadium papilligerum, and Allocreadium sp. ex Oreoleuciscus potanini from Mongolia. The DNA sequences of the 28S rRNA gene and the rDNA ITS2 region were obtained and then analyzed for phylogenetic inference. The analysis is complemented with the morphological descriptions for all four species. Phylogenetic analyses show that the newly obtained isolate of A. isoporum appeared to be genetically similar to previously obtained isolates of A. isoporum. Allocreadium dogieli probably belongs to the same evolutionary lineage of Allocreadium as A. crassum, while A. papilligerum to the same evolutionary lineage as Alocreadium transversale ex Cobitis taenia from Lithuania, but the detailed species composition of these lineages requires further elucidation. Allocreadium sp. was genetically close to Allocreadium sp. ex P. phoxinus from Primorski Krai, Russia, and a group of these Allocreadium had a sister relationship with Allocreadium khankaiensis. Our findings contradict some recent hypotheses about the phylogeography of Allocreadium spp.

Effects of dietary soybean meal inclusion on calcium-binding protein expression and inflammatory gene markers in liver and intestine of Atlantic Salmon (Salmo salar L.)

Atlantic Salmon (Salmo salar L.) are sensitive to the inclusion of soybean meal in the diet which can result in inflammation in the distal intestine. Expression of S100 genes have been shown to be upregulated as part of the inflammatory response to antinutritional factors in soybean meal. These genes are also involved in calcium homeostasis in marine teleosts. We examined expression of S100I2 and S100V2 genes coding for calcium-binding proteins in the distal intestine and liver between groups of Atlantic Salmon fed a fishmeal (FM) or soybean-meal (PM) diet for 12 weeks. These two genes have been previously shown to differ in binding motifs and share variable sequence identity. Juvenile Atlantic Salmon (71.25 ± 0.76 g) were cultured in 140 L tanks using flow-through freshwater at 15 oC and randomly assigned to FM or PM diet groups in triplicate. Fish were fed daily to satiation and subsampled from each tank every four weeks. Expression of S100I2 in the distal intestine was elevated by 8 weeks but expression did not differ between diets. Expression of S100V2 was significantly elevated in the distal intestine of fish fed the PM diet compared to fish fed the FM diet. Increased expression of S100V2 but not S100I2 at 8 and 12 weeks in fish fed the PM diet differs from observations in previous studies using Rainbow Trout and implies Atlantic Salmon raised in freshwater may regulate expression of S100V2 and S100I2 in their distal intestine differently than Rainbow Trout. Expression of S100I2 and S100V2 in liver was not different between dietary treatments. Semi-quantitative histological scores confirmed mild but significant distal enteritis in the PM diet group but not in the FM diet group. Overall, these results provide further understanding in the expression of S100 genes and inflammatory processes associated with soy-induced distal enteritis in salmonids.

Histopathological Changes Caused by Parasites in Carangoides Bajad Fish in the Red Sea, Jeddah

This research focused on discovering parasites in the fish Carangoides bajad (orange-spotted trevally) (Forsskal, 1775) that were captured from the Red Sea off Saudi Arabia. Carangoides bajad (n = 120) were collected during the spring and summer of 2019. Internal parasites were extracted and subjected to parasitological analyses and fish intestines were subjected to histopathological analyses. The average length and weight of Carangoides bajad were 39.88 ± 8.7 cm and 1.68 ± 0.58 kg, respectively. We identified Anisakis (17.5%), Lecithocladium (23.33%), and Bucephalus spp (29.17%) in the infected fish. Female fish outnumbered males, suggesting that sex significantly influence the prevalence of parasitic infections. Parasites, or evidence of parasitic infection, were not detected in small fish (weighing 0.5–0.90 kg or 1.0–1.49 kg, and 20.0–29.9-cm long). Similarly, the values of Fulton’s condition factor (K) ranged between 3.0–3.99 and 4.0–4.99, supporting the conclusion that these small fish were not infected with parasites. The data on larger fish (weighing 1.5–1.90 kg or 2.0–2.49 kg or 2.5–2.99 kg and length 20.0–29.9 cm or 30.0–39.9 cm or 40.0–49.9 cm or 50.0–59.9 cm) reveal that parasitic infections significantly influenced the length, weight, and Fulton’s condition factor (K) according to the prevalence and intensity of infection of Carangoides bajad. Histopathological examination revealed intestinal tissue damage; and 45% of inflamed tissues involved swelling of the intestinal villi. Further, we observed separation of the mucosal epithelia from the submucosa, proliferation of goblet cells, and lymphocyte infiltration accompanied by atrophy and lysis of intestinal villi. The present study demonstrates infection of Carangoides bajad with three types of parasites and documents their deleterious effects.

Molecular Characterization of Immunoglobulin M (IgM) and Polymeric Immunoglobulin Receptor (pIgR) and Expression Response to Vibrio harveyi Challenge in Leopard Coral Grouper (Plectropomus leopardus)

Immunoglobulin M (IgM) is the primary antibody in fish, which is transported from epithelial cells into the external secretion system by polymeric immunoglobulin receptor (pIgR). In this study, the full length of IgM and pIgR complementary DNA sequences from leopard coral grouper (Plectropomus leopardus) was characterized, and their expression levels under Vibrio harveyi infection were studied. cDNA sequence analysis showed that the pl-IgM heavy chain cDNA contained an open reading frame (ORF) of 1797 bp encoding a polypeptide of 597 amino acids consisting of a signal peptide, a variable region, and 4 constant regions. pl-pIgR (1041 bp) encodes 346 amino acids with 2 Ig-like domains (ILDs). The expression levels of pl-IgM and pl-pIgR in healthy fish were mainly in the intestine and spleen of fish, which indicates the relationship between the mucosal-associated lymphoid tissue and system lymphoid tissue. Messenger RNA (mRNA) expression profiles of pl-IgM and pl-pIgR were significantly increased in the intestine, head kidney, spleen, and liver after V. harveyi infection. The cDNA sequences of two ILDs were cloned and expressed in Escherichia coli BL21 (DE3). The recombinant pl-pIgR protein had antibacterial function against V. harveyi and Vibrio alginolyticus at 200 ng/μl. Our results indicate that pl-IgM and pl-pIgR are involved in the mucosal-associated immune and systemic immune response in the antibacterial immunity of leopard coral grouper.

Effects of mulberry leaf extract on the intestinal health of spotted sea bass (Lateolabrax maculatus)

Mulberry leaf extract (ELM) has the functions of promoting growth, antioxidant, improving intestinal microbial composition, thus providing a potential solution the occurrence of fish intestinal diseases. Therefore, this experiment was conducted to explore the effects of ELM on intestinal health of spotted sea bassLateolabrax maculatus. A total of 360 spotted sea bass (9.00 ± 0.02 g) were selected and randomly divided into 6 groups. Fish in each group were given feed with varying ELM concentration (0, 3, 6, 9, 12, 15 g/kg) for 52 days, respectively. Results show, dietary intake of 9 g/kg ELM increased the weight gain, specific growth ratio and feed intake of the spotted sea bass (P&amp;lt;0.05). Meanwhile, dietary intake of 9 g/kg ELM increased the activity of enteric trypsin, amylase and lipase (P&amp;lt;0.05). The enteric catalase activity was improved in fish fed with 3 g/kg ELM (P&amp;lt;0.05), while a limited effect of ELM on the activity of enteric superoxide dismutase, glutathione, and content of malonaldehyde was observed (P&amp;gt;0.05). ELM improved the morphology of fish intestine, as manifested in significant improvement in the length of intestinal villi, thereby increasing the surface area of the intestinal tract (P&amp;lt;0.05). Compared with the control group, dietary intake of ELM significantly increased the intestinal microbial ACE, Chao1, and Shannon indexes of fish (P&amp;lt;0.05), indicated that the intestinal microbial composition and the abundance of the dominant flora of fish were improved. The above results suggested that the dietary supplementation of about 9 g/kg ELM can improve the growth performance, enteric antioxidant capacity, and intestinal morphology and microbial composition, therefore improving the intestinal health of spotted sea bass. The research results provide a theoretical basis for the application of ELM in improving the enteric health of spotted sea bass, and providing a potential solution the occurrence of fish intestinal diseases.

Microbial community structure and diversity in fish-flower (mint) symbiosis

The fish-flower symbiosis model is an eco-friendly sustainable farming technology combining plants, fish and microorganisms in a recirculating aquaculture system. However, there are few studies on the structure and diversity of microbial communities in fish intestines, culture water and plant roots during fish-flower symbiosis. Here, we cultured carp (Cyprinus carpio), crucian carp (Carassius auratus) and grass carp (Ctenopharyngodon idella) with mint (Mentha spicala L.) and extracted total genomic DNA from intestinal microorganisms, culture-water microorganisms and root microorganisms for each fish species for high-throughput sequencing of 16S rRNA genes. Analysis of microbial community structure and diversity revealed changes in abundance of microbial genera in the intestines and culture water of each fish species, including changes in the dominant taxa. Pirellula, Truepera, Aquincola, Cetobacterium and Luteolibacter were widespread in the fish intestine, culture water and mint root system. This study revealed the effects of mint feeding on the structure and diversity of microbial communities of fish, water bodies and the mint root system during fish-flower symbiosis, providing a theoretical reference for the promotion and application of fish-flower (mint) symbiosis technology and healthy fish culture technology.

First insight in element localisation in different body parts of the acanthocephalan Dentitruncus truttae using TEM and NanoSIMS

Acanthocephalans, intestinal parasites of vertebrates, are characterised by orders of magnitude higher metal accumulation than free-living organisms, but the mechanism of such effective metal accumulation is still unknown. The aim of our study was to gain new insights into the high-resolution localization of elements in the bodies of acanthocephalans, thus taking an initial step towards elucidating metal uptake and accumulation in organisms under real environmental conditions. For the first time, nanoscale secondary ion mass spectrometry (NanoSIMS) was used for high-resolution mapping of 12 elements (C, Ca, Cu, Fe, N, Na, O, P, Pb, S, Se, and Tl) in three selected body parts (trunk spines, inner part of the proboscis receptacle and inner surface of the tegument) of Dentitruncus truttae, a parasite of brown trout (Salmo trutta) from the Krka River in Croatia. In addition, the same body parts were examined using transmission electron microscopy (TEM) and correlated with NanoSIMS images. Metal concentrations determined using HR ICP-MS confirmed higher accumulation in D. truttae than in the fish intestine. The chemical composition of the acanthocephalan body showed the highest density of C, Ca, N, Na, O, S, as important and constitutive elements in living cells in all studied structures, while Fe was predominant among trace elements. In general, higher element density was found in trunk spines and tegument, as body structures responsible for substance absorption in parasites. The results obtained with NanoSIMS and TEM-NanoSIMS correlative imaging represent pilot data for mapping of elements at nanoscale resolution in the ultrastructure of various body parts of acanthocephalans and generally provide a contribution for further application of this technique in all parasite species.

Digestion of preserved and unpreserved fish intestines for microplastic analysis with emphasis on quality assurance

BACKGROUND, Different preservation media used on fish samples may influence the digestion of organic matter for microplastic (MP) particle detection. Comparison of fresh and conserved fish is thereby problematic. OBJECTIVE, For quality assurance purposes and comparability of MP research, a method for digestion of preserved tissue like intestine with little impact on most MP particles was implemented. METHODS, Conserved fish samples were digested using SDS, KOH and Fenton’s reagents. The effect of the different chemicals used on different MP particles was then analyzed using Raman hit quality. Therefore, different filter materials were investigated using PMMA particles. RESULTS, Moist grided nitrocellulose filter was found best suited for this study. The effects of this digestion protocol on different polymer particles differed among polymers. Two of the used polymer particles dissolved during SDS + KOH treatment. PVC hard showed the highest loss of Raman hit quality (29.5 %). Some fish showed residues of sand or chitin from insects depending on their feeding strategy which could not be digested using this protocol. CONCLUSION, Not every polymer could be detected reliably using this protocol. For residues like sand or chitin, a density separation and enzymatic chitin degradation using chitinase may be needed, which could be implemented into this protocol.