Lamellar Fusion Research Articles

Histopathological study of parasitic effect of Dactylogyrus vastator (Nybelin, 1924) on the Catla catla in culture ponds in Darbhanga

The current investigation was undertaken to study the gill histopathologies due to infestation of helminth parasite, monogenetic trematode, Dactylogyrus vastator (Nybelin, 1924) in the Indian major carp, Catla catla. There were only symptomatic samples of diseased fishes comprised of fingerlings and adults of Catla catla collected and examined. Behaviour respond studied- partial suffocation, lethargic swimming and clinical sign observed as their gills were very pale in colour and had haemorrhagic and inflamed areas at the sites of parasite attachments. The significant histopathological lesions and changes were seen in the gills where the parasites were found attached to the lamellar tissues causing local erosions of the epithelium and hyperplasia of the secondary lamellar epithelium and fusion of adjacent secondary lamellae, vascular congestion leading to aneurysm besides, clumbing of the tips in secondary lamellae, congested gill showed accumulation of blood leading to swelling hypertrophy in secondary lamellae, autolysis of epithelium and secondary lamellae and severe edema and necrosis were observed in gill of C. catla. No changes were noticed in other organs of the affected fishes. In severe infestations the fishes showed growth retardation. The histopathological analysis for parasites in fish will be useful tool for fish health management.

Effect of CO2 exposure on the antioxidant enzymes activity and gill histology of adult zebrafish (Danio rerio)

Increase in carbon dioxide level is considered as a threat to all living organisms and in particular aquatic organisms are vulnerable. Although a number of studies were carried out to predict the effect of increased CO2 with marine organisms, fresh water fish were the least concerned ones. Therefore, the aim of this study was to study the effect of antioxidant enzymes in zebrafish exposed to acute concentration of CO2 (based on prediction for 2300). Three ranges of pH were selected below the range where no fatality was observed, 6.0 – 6.5, 5.5 – 6.0 and 5.0 – 5.5. Antioxidant enzyme analysis of superoxide dismutase (SOD), catalase (CAT), lipid peroxidation (LP), glutathione reductase (GR) and glutathione peroxidase (GPx) was performed for the tissues, liver, gills and muscles. Although a significant decrease in SOD activity was observed in all three tissues, only a slight variation in CAT activity was found in all the tissues. MDA content which is an indicator of lipid peroxidation showed an increasing pattern in all the tissues. A slight increase in GR activity was found in all the tissues; however, a significant decrease in GPx activity was noted. Further, the histology of gills exposed to CO2 showed marked damage and injury including lamellar fusion and necrosis. Our study concludes that exposure to CO2 has led to oxidative stress which has resulted in cellular injury and damage

Alterações histopatológicas em brânquias de peixe-zebra (Danio rerio) e girinos de rã-touro (Lithobates catesbeianus) causada pelo uso de formaldeído

Formaldehyde is a carcinogenic and aggressive agent mainly to epithelial tissues. However, for rearing aquatic organisms its use is common for the treatment of fungi and parasites, and the use of incorrect doses can harm the health and life of these animals. The fish species Danio rerio and the tadpoles of the species Lithobates catesbeianus are internationally recognized for use in aquatic toxicology tests. We aimed identify the effects caused by formaldehyde on the gills of these two experimental models used in aquatic toxicology, verifying the susceptibility of both species. Acute and chronic tests with formaldehyde were conducted for experiment. We found that the formaldehyde in the higher concentration caused injuries to the gills of both fish and tadpoles, with a loss and displacement of epithelium, vascular congestion, telangiectasia and lamellar epithelial lifting/edema (possible aneurysm), hyperplasia and hypertrophy of epithelial cells, lamellar fusion in addition to the proliferation of mucus-secreting cells and chloride cells. Despite structural differences, the histological changes caused by chronic exposure to formaldehyde in sublethal concentrations were similar in both organisms and we recommend reviewing its use in prophylaxis and in prolonged treatments with this chemical.

Biochemical, genotoxic, histological and ultrastructural effects on liver and gills of fresh water fish Channa punctatus exposed to textile industry intermediate 2 ABS

The study was planned to assess the acute toxicity of textile industry intermediate, 2 amino benzene sulfonate (2 ABS) through biochemical, genotoxic, histopathological and ultrastructural (SEM) analysis in liver and gills of fresh water fish Channa punctatus. The fish were subjected to two sublethal concentrations (2.83 mg/30 g b. w. and 5.66 mg/30 g b. w.) for 96 h. A significant (p ≤ 0.05) increment in the enzymatic activity of catalase (CAT), superoxide dismutase (SOD) and glutathione reductase (GR) was observed followed by decline on CAT-SOD after 96 h of exposure in both the tissues, whereas increment in malondialdehyde (MDA) levels were observed throughout the exposure period for both the concentrations. Comet assay also showed elevated tail length and % tail DNA throughout the exposure period, marking maximum damage after 96 h for both the tissues. Light microscopy divulged several anomalies including: infiltration of lymphocytes, sinusoidal dilations, necrosis, vacuolation in liver and secondary lamellae fusion, telangiectasia and epithelial uplifting in gills. The highest degree of tissue change (DTC) in liver (50.33 ± 0.88) and gill (42.33 ± 2.18) was recorded with the highest concentration after 96 h of exposure. Scanning electron microscopy (SEM) also reaffirmed several alterations in liver and gills of fish. The findings of the present study inflict changes in liver and gills, marking the interference of 2 ABS with the normal functioning by suppressing the enzymatic activity, accelerating the lipid peroxidation, enhancing DNA damage and by disrupting normal architecture of liver and gills, making it toxic towards the fish even at sub-lethal concentrations.

Integration of transcriptomics and metabolomics reveals damage and recovery mechanisms of fish gills in response to nanosilver exposure.

Toxic effects of silver nanoparticles (AgNPs) on fish gills have been widely reported but the recoverability of AgNPs-induced fish gill injuries is still unknown. In this study, combined multiomics and conventional toxicological analytical methods were used to investigate the changes in the gills of common carp responses to AgNPs (0.1mg/L) toxicity after 24h exposure and 7-day recovery. Conventional toxicological results showed that AgNPs exposure significantly increased silver content in gills and caused epithelial hyperplasia and lamellar fusion. After the recovery period, the silver content in fish gills significantly decreased; accompanied by the disappearance of histopathological characteristics in fish gills. Multiomics results revealed that AgNPs exposure resulted in the differential expression of 687 genes and 96 metabolites in fish gills. These differentially expressed genes (DEGs) and metabolites mainly participate in amino acid, carbohydrate, and lipid metabolisms, and are significantly enriched in the tricarboxylic acid (TCA) cycle. After the recovery period, the number of DEGs and metabolites in gills decreased to 33 and 90, respectively. Moreover, DEGs and metabolites in the TCA cycle recovered to control levels. In summary, the present study found that AgNPs-induced fish gill toxicity showed potential recoverability at molecular and phenotype levels.

Lethal dose and histopathological alterations induced by Aeromonas salmonicida in experimentally challenged common carp, Cyprinus carpio

Aeromonas salmonicida is the obligate pathogen of fishes having zoonotic potential. It is reported to cause considerable losses in world aquaculture. The current study has successfully demonstrated the induction of histopathological lesions in experimentally infected common carp. In the current study, the lethal concentration (LD50-96 h) of typical A. Salmonicida for common carp was found to be 1.5 × 107CFU mL−1. About 40% and 60% fish mortalities occurred after 72 h in the groups inoculated with 107 and 108 CFU mL−1 bacterial suspension, respectively. The fish challenged with A. salmonicida showed symptoms like abnormal swimming behaviour, lethargy, intra-abdominal fluid, haemorrhages on the ventral side of the body, vent and fins. The signs proceeded with the death of fish. In the histological sections, severe pathological alterations were reported in the tissue sections of internal organs. The microscopic observation showed sinusoidal and large blood vessel congestion in the liver, profuse haemorrhage, necrosis and infiltration of blood cells in the internal organs. The tubular architecture was lost with the infiltration of leucocytes in the kidney. In gills, more intense and prominent lamellar fusion was observed with leucocytic infiltration, telangiectasia and hyperplasia of lamellar epithelial cells. In summary, we have experimentally induced the typical A. salmonicida infection in common carp. The study will provide a research foundation for further studies on the host-pathogen interaction, therapeutics and epidemiology of A. salmonicida.

Morphological, molecular, and histopathological characterization of a new species of Henneguya infecting farmed Astyanax lacustris in Brazil

The present study describes the morphological, histopathological and SSU rDNA data of a new myxosporean species infecting farmed Astyanax lacustris fish from the state of São Paulo, Brazil. Henneguya lambariensis sp. nov. was found infecting the gills, and the plasmodial development resulted in displacement, blood congestion, compression, deformation and lamellar fusion, stretching of the epithelia, hyperplasia of the epithelial cells, edema, and mild infiltration of the mast cells and lymphocytes. The SSU rDNA sequencing resulted in the sequencing of 1804 nucleotides that did not correspond to any myxosporean sequences deposited in GenBank. The closest phylogenetic affinity of the new species was to the South American Henneguya loreotoensis and Henneguya guanduensis, which also parasite the gills. The present study suggests this new myxosporean species has considerable pathogenic potential, and health monitoring should be implemented in A. lacustris fish farms to ensure production.

Histopathological changes in gills and liver of Clarias gariepinus fingerlings exposed to acute concentrations of dry cell battery

Waste dry cell batteries are frequently improperly disposed and subsequently washed into water bodies-- causing deleterious effects on fish particularly Clarias gariepinus which inhabits diverse freshwater habitats. Acute toxicity of water-soluble fractions of waste dry cell batteries was investigated on C. gariepinus fingerlings under laboratory conditions in 96 hours. Ten (10) C. gariepinus fingerlings were exposed to acute concentrations (0.31, 0.63, 1.25, 2.50, and 5.00 g/L) of waste dry cell batteries and a control (0.00 g/L), each duplicate replicated. Histopathological alterations evident in the gills were lamellar fusion, hyperplasia, inter-lamella space occlusion, hypertrophy and erosion of secondary lamellae. The liver showed nuclear and hepatocytes degeneration, vacuolation and portal congestion. Acute concentrations of water-soluble fractions of waste dry cell batteries caused significant (P<0.05) changes in the histomorphology of the gills and liver of C. gariepinus fingerlings, therefore indiscriminate disposal of waste dry cell batteries around riparian ecosystem should be safeguarded to reduce the declining diversity and abundance of freshwater fish species.
 Keywords: African catfish, 96 hr.LC50, Fingerlings, Histopathology Zinc-carbon battery

Dietary Phytogenics and Galactomannan Oligosaccharides in Low Fish Meal and Fish Oil-Based Diets for European Sea Bass (Dicentrarchus labrax) Juveniles: Effects on Gill Structure and Health and Implications on Oxidative Stress Status.

An effective replacement for fish meal (FM) and fish oil (FO) based on plant-based raw materials in the feed of marine fish species is necessary for the sustainability of the aquaculture sector. However, the use of plant-based raw materials to replace FM and FO has been associated with several negative health effects, some of which are related to oxidative stress processes that can induce functional and morphological alterations in mucosal tissues. This study aimed to evaluate the effects of dietary oligosaccharides of plant origin (5,000 ppm; galactomannan oligosaccharides, GMOS) and a phytogenic feed additive (200 ppm; garlic oil and labiatae plant extract mixture, PHYTO) on the oxidative stress status and mucosal health of the gills of juvenile European sea bass (Dicentrarchus labrax). The experimental diets, low FM and FO diets (10%FM/6%FO) were supplemented with GMOS from plant origin and PHYTO for 63 days. GMOS and PHYTO did not significantly affect feed utilization, fish growth, and survival. GMOS and PHYTO downregulated the expression of β-act, sod, gpx, cat, and gr in the gills of the fish compared with that in fish fed the control diet. The expression of hsp70 and ocln was upregulated and downregulated, respectively, in the GMOS group compared with that in the control group, whereas the expression of zo-1 was downregulated in the PHYTO group compared with that in the GMOS group. The morphological, histopathological, immunohistochemical, and biochemical parameters of the fish gills were mostly unaffected by GMOS and PHYTO. However, the PHYTO group had lower incidence of lamellar fusion than did the control group after 63 days. Although the tissular distribution of goblet cells was unaffected by GMOS and PHYTO, goblet cell size showed a decreasing trend (−11%) in the GMOS group. GMOS and PHYTO significantly reduced the concentration of PCNA+ in the epithelium of the gills. The above findings indicated that GMOS and PHYTO in low FM/FO-based diets protected the gill epithelia of D. labrax from oxidative stress by modulating the expression of oxidative enzyme-related genes and reducing the density of PCNA+ cells in the gills of the fish.

Aeromonas hydrophila Infection on Culturing Sea Bass (Lates calcarifer) in Valaichennai Lagoon, Batticaloa, Sri Lanka

Background: The floating cage cultured seabass (Lates calcarifer) at the site of Valaichennai lagoon in Batticaloa District, East coast of Sri Lanka was reported acute mortality within short period of stocking the fish in the cage.Methods: Present study was focused to study the aetiology that caused by infection on culturing sea bass at the site. Gross pathological and histopathological examinations were carried in moribund and naïve fishes. Bacteriological, mycological screening and antibiotic sensitive test for isolation of pathogen were carried out to find out the causes. Water quality, feed quality and their management were assessed at the time of disease outbreak.Result: Investigations primarily revealed that infection was initiated with the flooding due to heavy monsoonal season and sudden fluctuation in salinity. The gross pathological signs were change of skin colour, large irregular haemorrhages on the body surface, cloudy eye, ulcers on skin, lamellar fusion, fin rot and tail rot as well as histopathological findings such as necrosis in muscles, liver and kidney tissues, cyst formation by secondary infected pathogens proved that pathogen was bacteria. Gram staining also offered clear indication of gram-negative rod-shaped bacteria and, the particular pathogenic bacteria was confirmed as Aeromonas hydrophila through further analyses such as Oxidative test, Indole test and antibiotic sensitivity test. Antibiotic sensitivity test also point out that the Tetracycline as one of the effective antibiotics for the Aeromonas hydrophila infection. The improper feeding management and sudden salinity fluctuation pave the path for acute infection of A. hydrophila and ultimately lead to the high mortality in cage culture.

Histopathological alterations caused by monogenean parasites the gills of tambaqui Colossoma macropomum (Serrasalmidae)

Monogeneans are ectoparasites of fish with a global distribution. In farmed fish, high infestations may result in morbidity and mortality. This study investigated the histopathological effects of three species of monogeneans Anacanthorus spathulatus, Notozothecium janauachensis and Mymarothecium boegeri on the gills of farmed Colossoma macropomum. Parasitological indices revealed a prevalence of 100%, and a mean abundance of 81.3 ± 11.8. This infection caused displacement of the gill epithelium, focal hyperplasia of epithelial cells, lamellar fusion, congestion and shortening of the secondary lamellae of gills, in addition a complete fusion of the secondary lamellae. However, these tissue alterations were reversible and punctually located lesions, which may not compromise the normal functioning of gills. Lastly, this study showed the potential damages caused by parasite monogeneans to gills of infested fish, thus sanitary management is essential for the growth of fish farm of C. macropomum.

Quality of water from fish farms and histopathological analysis of tilapia ( Oreochromis sp.) in São José de Ribamar and Paço do Lumiar, state of Maranhão, Brazil

The present work aimed to use histopathological gill biomarkers in tilapia (Oreochromis sp.) and physicochemical and microbiological analyses of water in the evaluation of impacts to fish farms located in São José de Ribamar and Paço do Lumiar, state of Maranhão, northeastern Brazil. Histopathological analyses performed on gills indicated morphological alterations in all tissues analysed. The lesions found were as follows: epithelial lifting, lamellar epithelium hyperplasia, blood vessel congestion, lamellar fusion, blood sinus dilation and lamellar aneurysm. Temperature, D.O., salinity and nitrite values obtained were considered within recommended standards. The pH verified in a pisciculture located in Paço do Lumiar is considered potentially stressful to fish and, therefore, predisposing to pathologies. Ammonia in a fish farm in São José de Ribamar is considered sublethal. In all fish farms evaluated, the presence of high counts of total coliforms for fish farms of São José de Ribamar was verified. Escherichia coli was verified in a cultivation in São José de Ribamar indicating faecal contamination of the nursery water by the flow of some source of domestic effluent. The integration of studies with physical, chemical and biological variables generates important data to evaluate the quality of fish production.

High environmental temperature and low pH stress alter the gill phenotypic plasticity of Hoven's carp Leptobarbus hoevenii.

Climate warming and low pH environment are known to negatively impact all levels of aquatic organism from cellular to organism and population levels. For ammonotelic freshwater species, any abiotic factor fluctuation will cause disturbance to the fish, specifically at the gills which act as a multifunctional organ to support all biological processes. Therefore, this study was designed to investigate the effect of temperature (28 vs. 32°C) and pH (7.0 vs. 5.0) stress on the gill plasticity of Hoven's carp after 20 days of continuous exposure. The results demonstrated that high temperature and low pH caused severe changes on the primary and secondary lamellae as well as the cells within lamellae. An increasing trend of the proportion available for gas exchange was noticed at high temperature in both pH exposures, which resulted from a reduction of the primary lamellae width with elongated and thinner secondary lamellae compared to fishes at ambient temperature. Following exposure to high temperature and acidic pH, Hoven's carp experienced gill modifications including aneurysm, oedema, hypertrophy, curling of secondary lamellae, epithelial lifting, hyperplasia and lamellae fusion. These modifications are indicators of the coping mechanism of Hoven's carp to the changing environment in order to survive.

Histopathological alterations in gills, kidney and liver of Nile Tilapia (Oreochromis niloticus) fingerlings exposed to aqueous leaf extract of Desert Date (Balanites aegyptiaca)

One of the many biomarkers for determining the effects of pollutants on fish is changes in organ histopathology. Leaves of Balanites aegyptiaca have been reported to have phytochemicals with fish anaesthetic property. This study sought to determine the effect of graded acute concentrations (200.00, 250.00, 300.00.350.00 and 400.00 mg/L) of B. aegyptiaca on histopathology of gills, kidney and liver of mixed sex of Oreochromis niloticus fingerlings. A total of 120 O. niloticus fingerlings (mean weight 23±0.03 g and mean total length 12.50±0.39 cm) were exposed to the plant extract. Paraffin wax method and haematoxylin-eosin staining techniques of tissue processing were adopted for the examination of the gills, kidney and liver. Dose-dependent histopathological changes were observed in the three organs (gills, kidney and liver) i.e. histopathological alterations increase with increase in concentration of the plant extract. Gills showed lamellae fusion, haemorrhage, desquamation, atrophy and secondary lamellae erosion while kidney and liver indicated atrophy, necrosis, haemorrhage, hyperplasia and hypertrophy. Structural alterations were evident in the gills, kidney and liver of O. niloticus fingerlings exposed to the concentrations of aqueous crude leaf extract of B. aegyptiaca therefore it should be used with caution during fish anaesthesia.
 Keywords: Histopathology; Gill; Kidney; Liver; Balanites aegyptiaca; Oreochromis niloticus.

Investigation of the Initial Host Response of Naïve Atlantic Salmon (Salmo salar) Inoculated with Paramoeba perurans.

Amoebic Gill Disease (AGD), caused by the ectoparasite Paramoeba perurans is characterised by hyperplasia of the gill epithelium and lamellar fusion. In this study, the initial host response of naïve Atlantic salmon (Salmo salar) inoculated with P. perurans was investigated. Using gel-free proteomic techniques and mass spectrometry gill and serum samples were analysed at 7 timepoints (2, 3, 4, 7, 9, 11 and 14 days) post-inoculation with P. perurans. Differential expression of immune related proteins was assessed by comparison of protein expression from each time point against naïve controls. Few host immune molecules associated with innate immunity showed increased expression in response to gill colonisation by amoebae. Furthermore, many proteins with roles in immune signalling, phagocytosis and T-cell proliferation were found to be inhibited upon disease progression. Initially, various immune factors demonstrated the anticipated increase in expression in response to infection in the serum while some immune inhibition became apparent at the later stages of disease progression. Taken together, the pro-immune trend observed in serum, the lack of a robust early immune response in the gill and the diversity of those proteins in the gill whose altered expression negatively impact the immune response, support the concept of a pathogen-derived suppression of the host response.

The effects of salinity on growth, gill tissue and muscle cellularity in Lophiosilurus alexandri juvenile, a Neotropical freshwater catfish

The present study investigated the effects of salinity on growth, mortality, gill morphology and muscle cellularity in Lophiosilurus alexandri. Fish were submitted to the following salinity for 28 days: 0 (S0), 2.5 (S2.5), 5.0 (S5), 7.5 (S7.7) and 10 (S10) ppt. Growth and protein efficiency ratio (PER) decreased with the increase of salinity. All fish from S10 died between the 16th and 21st day of the experiment. Mortality in S7.5 was 78% at the end of 28 days of salinity exposure. Increased salinity was accompanied by increased vascular congestion, hyperplasia of gill filament epithelium, lamellar fusion and loss of structural integrity of pillar cells. Fish at S2.5 and S5 had higher mucosal cell hyperplasia. Chloride cell quantity was higher in fish in the S2.5 to S7.5. In general, L. alexandri juvenile exposed to treatments of freshwater and S2.5 had similar patterns of muscle cellularity, with high averages for the most of the variables of muscle cellularity evaluated. The large fibre size classes tended to decrease with increasing salinity. L. alexandri juveniles may be cultivated up to 2.5 g of salt/L, and superior concentrations change growth, induce damage to gills and modify muscle cellularity.

Evidence of cytogenetic and histological damage in specimens of Astyanax lacustris (Pisces, Characidae) exposed to the hydrogen cyanide-based herbicide Dormex®

The herbicide Dormex®, a solution of hydrogen cyanamide, is a growth regulator capable of breaking the dormancy of fruit plants, and is commonly applied in agriculture. However, the biological effects of this product on non-target organisms are unknown. The present study investigated the biological response of Astyanax lacustris (Lütken, 1875) specimens exposed to Dormex® using a chromosome aberration test, the mitotic index, and the histological analysis of the gills. Forty specimens of Astyanax lacustris were obtained from a local breeding facility and divided into 10 groups (nine experimental and one control) with four fish in each aquarium (group). The control group was maintained for 24 hours in dechlorinated water while the experimental groups were allocated to one of nine different treatments, with three concentrations of Dormex®, 0.05, 0.1 and 0.5 mL L-1, and exposure for 24, 48 and 72 hours. The fish exposed to Dormex® presented chromosomal aberrations of a number of types, including chromosomal breaks, acentric fragments, decondensation, and gaps at the three Dormex® concentrations, at all exposure times. The mitotic index decreased significantly in comparison with the control group. The histological preparations of the gills revealed alterations such as hyperplasia, and lamellar fusion and edema, whereas in the control group the structure of the gills was preserved. The cytogenetic analysis revealed the genotoxic potential of the herbicide Dormex® and the morphological alterations of the gills demonstrated the sensitivity of the fish, which responded rapidly to the stressor. These findings reinforce the need for special care and restrictions on the use of these herbicides in agricultural areas located near aquatic environments.

Hydrogen peroxide treatment of Atlantic salmon temporarily decreases oxygen consumption but has negligible effects on hypoxia tolerance and aerobic performance

Hydrogen peroxide is widely used as a treatment of ectoparasite (e.g. salmon lice, amoebic gill disease) affected Atlantic salmon (Salmo salar) in aquaculture but has frequently caused unacceptable levels of mortality. Hydrogen peroxide toxicity increases with dose, exposure duration and temperature, and can cause an acute stress response, oxidative stress, gill damage, respiratory acidosis and altered gas and ion exchange. The combined stress effects have the potential to cause sub-lethal impacts on aerobic capacity that affects hypoxia tolerance and swimming performance. Here, we tested the sub-lethal effects of hydrogen peroxide treatment on the aerobic capacity, hypoxia tolerance and gill histopathology of healthy Atlantic salmon. Hydrogen peroxide treatment (1250 ppm at 12 °C for 20 min) caused a significant but negligible reduction in acute hypoxia tolerance (lost equilibrium at slightly higher levels of dissolved oxygen) immediately following treatment, but not in the 14 days afterwards. Immediately following hydrogen peroxide treatment (1250 ppm at 16 °C for 20 min) oxygen consumption was reduced for up to 20 min in normoxia and 40 min in hypoxia. However, following transient reductions in oxygen consumption the maximum metabolic rate and Ucrit measured in a swim flume were unaffected by hydrogen peroxide exposure (1250 ppm at 16 °C). Resting metabolic rate was unaffected by hydrogen peroxide treatment in all experiments. Hydrogen peroxide exposure caused non-homogenous lamellar epithelium lifting with subepithelial oedema and multi-focal lamellar fusion. The reduction in oxygen consumption following hydrogen peroxide treatment was likely caused by an increase in blood oxygen due to the breakdown of hydrogen peroxide by catalase and other oxidative enzymes in the fish tissues. Ultimately, hydrogen peroxide did not affect aerobic performance and had negligible impacts on hypoxia tolerance, suggesting that hydrogen peroxide has minimal sub-lethal impacts on aerobic performance of healthy Atlantic salmon at the doses used here.

Histopathological and calreticulin changes in the liver and gill of Takifugu fasciatus demonstrate the effects of copper nanoparticle and copper sulphate exposure

Copper nanoparticles (Cu-NPs) are water pollutants, which has significant toxic environmental effects. However, the effects of Cu-NPs on Takifugu fasciatus are still relatively unknown. Compared with the control (no add CuSO4 and Cu-NPs). This study aims to describe the pathological changes in the gill and liver of pufferfish exposed to CuSO4 (Cu2+ for short) and Cu-NPs dissolved at a concentration of either 20 or 100 μg/L, in a semi-static waterborne exposure regime for 28 days. All Cu treatments resulted in organ injuries, and the pathologies observed following exposure to Cu-NPs were broadly of the same type as those observed following exposure to Cu2+. In the gill, these included lamellar fusion, clubbed tips, and mucocytes swollen, and in the liver included oedema, aggregation of blood cells, and necrosis. Furthermore, enzyme activity assays revealed that Ca2+ -ATP activity significantly increased under the influence of Cu, whilst Na+-K+-ATPase activity was significantly inhibited. In this study, the CRT in T. fasciatus (referred to as TfCRT) was identified and full-length cDNA sequences were characterized. Subsequently, RT-PCR and western blot analysis were carried out to assess the expressions of TfCRT in the gill and liver at both the mRNA and protein levels. Under both the Cu-NPs and Cu2+ treatments, both the mRNA and protein expressions of TfCRT were considerably higher in the gill and liver compared to that of the control treatment. Furthermore, there were no significant differences between Cu-NPs and Cu2+ treatment (at the same treatment concentration) in the expressions of TfCRT at the mRNA or protein levels. Overall, both Cu2+ and Cu-NPs had negative effects on T. fasciatus, and Cu-NPs had the toxic effects similar to dissolved Cu. Our results provide the ecological safety data service of Cu-NPs in water, and provide a reference for the health T. fasciatus aquaculture.

The Effect of Adding Bacillus NP5 to Feed on Growth, Survival Rate, and Protection Against Aeromonas hydrophila of Catfish (Clarias sp.)

Probiotics are useful organisms in preventing the spread of disease in aquaculture. Therefore this study aims to evaluate the effect of administering Bacillus NP5 on the growth, survival rate, and histology of catfish with Aeromonas hydrophila infection. To achieve this, catfish (7.75 ± 0.02 g) were reared for 45 days with a density of 20 per tank. Furthermore, the study consisted of 4 treatments and 3 replications, namely K+: 0% Bacillus NP5+0.1 mL A. hydrophila injection, K-: 0% Bacillus NP5 + without A. hydrophila injection, A: 0.3% Bacillus NP5, and B: 0.8% Bacillus NP5. The results showed that the addition of probiotics significantly increased the growth and survival rate of catfish (P <0.05) compared to K+. The higher value of specific growth rate was found in treatments A and B (0.22 ± 0.03 and 0.23 ± 0.03% day-1, respectively) and the lowest in K+ (0.14 ± 0.03% day-1). Also, the tissue damage in K+ was higher than in the probiotic treatment. Besides, hyperplasia, congestion, and secondary lamella fusion in the gill tissue were found in the K+, while other treatments were found only in hyperplasia. Melanomacrophages occurred in catfish kidney tissue for all treatments, however, hydropic degeneration was found in the control treatment. The addition of Bacillus NP5 in feed resulted in higher growth, survival, and tissue damage compared to K+. Also, the addition of 0.8% Bacillus NP5 resulted in less catfish tissue damage.