Melanomacrophage Centers Research Articles

Endoparasite diversity and liver alterations in Hoplerythrinus unitaeniatus and Cichlasoma bimaculatum in a quilombola area in Maranhão, Brazil.

Our aim was to assess endoparasite diversity and liver alterations in Hoplerythrinus unitaeniatus (jeju) and Cichlasoma bimaculatum (acará preto) in a quilombola area in Maranhão, Brazil. For this, 21 H. unitaeniatus and 21 C. bimaculatum were caught in a natural environment and transported to a laboratory. After these had been euthanized, endoparasites were collected and identified. Liver alterations were evaluated histological analysis based on the severity of each lesion: stage I, organ functioning not compromised; stage II, more severe lesions that impair normal functioning of the organs; and stage III, very severe and irreversible lesions. Among the fish evaluated, 71.43% H. unitaeniatus and 61.90% C. bimaculatum were parasitized. Contracaecum sp. was found in both species; while acanthocephalans, only in H. unitaeniatus. The alterations were vacuolization, nucleus in the cell periphery, deformation of the cell outline, melanomacrophage center, hyperemia, cytoplasmic degeneration and nuclear vacuolization. Through calculating a histological alteration index, it was found that 26.19% of the specimens presented lesions in stage I; 38.09% lesions in stage II and 9.52% lesions in stage III. It was concluded that there is high prevalence of Contracaecum sp. and that the liver lesions may be adaptive responses by the fish to endoparasitic infection.

Iron deposition in the liver and guts of giant South American freshwater turtle Podocnemis expansa (Schweigger 1812) from a commercial breeding farm in Acre, Brazil

Wildlife turtles are endangered species because of the traditional capture of eggs and adult animals in Northern Brazil, such as the South American freshwater turtles (Podocnemis expansa). Successful conservation efforts in order to keep them in captivity and fed commercial fish chow may lead to physiological changes and systemic pathologies. Thus, in the present study, were evaluated the liver and digestive tract of 14 giant South American freshwater turtles microscopically and described the histopathological changes related from commercial breeding and captivity. There was the presence of ferric ions in the stomach epithelium and macrophages with ferric beads in crypts and intestinal villi. In the liver, it was observed disruption of hepatic architecture and liver hemosiderosis. There was the presence of large melano-macrophage centers (MC) filled with ferric ions throughout the liver parenchyma. The size of MC ranged from 25.3 x 31.3 μm up to 196.7 x 168.7 μm and occupied between 9.0 ± 2.9% and 37.5 ± 9.8% of the liver parenchyma area. Those findings can be influenced by age, malnourishment, or ammonia intoxication with posterior anemia, but all those hypotheses must be tested in the future.

Trichlorfon exposure in common carp (Cyprinus carpio L.) leads to oxidative stress, neurotoxicity, and immune responses

Organophosphorus insecticides, which are widely used to control parasitic infections, could accumulat in the environment and organisms, and their potential toxicity is a great concern. In this study, common carp (Cyprinus carpio L.) was exposed to different concentrations of trichlorfon (0, 0.1, 0.5, and 1.0 mg/L) for 28 days. The oxidative stress in brain and liver, the neurotransmitter contents in brain, and immune responses were investigated. Results revealed more severe oxidative stress effects in liver than in brain, including significant suppressive activities of superoxide dismutase, glutathione peroxidase, and total antioxidant capacity (T-AOC); reduced glutathione content; and increased reactive oxygen species and malondialdehyde contents in liver. Meanwhile, only the T-AOC activity decreased in the brain of trichlorfon-exposed groups. For neurotransmitters, the contents of 5-hydroxyindoleacetic acid, choline, and acetylcholine were all reduced after trichlorfon exposure. In the immune responses, alkaline phosphatase activity significantly decreased, while the lysozyme content significantly increased upon exposure to trichlorfon. Meanwhile, trichlorfon significantly increased the contents of inflammatory cytokines, namely, tumor necrosis factor-α, interleukin (IL)-1β, IL-6, IL-12, and transforming growth factor β, and significantly decreased the IL-10 content. Moreover, histological observations showed increased numbers of melano-macrophage centers in the head kidney and spleen of exposed common carp. Taken together, the results demonstrated that trichlorfon induced more severe oxidative stresses in liver than in brain, with the presence of neurotoxicity. Trichlorfon could also affect the immune responses in common carp.

Effect of poultry offal silage with or without betaine supplementation on growth performance, intestinal morphometry, spleen histomorphology of Nile tilapia (Oreochromis niloticus) fingerlings.

Fishmeal (FM) is the main protein source in fish feed. However, it is quite expensive due to its limited resources. Therefore, finding a dietary alternative to the FM to sustain fish production is crucial, and the current study was performed to assess the impact of poultry offal silage (POS) with or without betaine supplementation; as an effective and cheaper alternative to FM; on feed efficiency, growth performance, spleen morphology and intestinal morphometry of Nile tilapia (Oreochromis niloticus) fingerlings. Four dietary treatments were formulated: (1) FM based diet, (2) FM-B; FM diet +0.7% betaine, (3) POS diet and (4) POS-B; POS diet +0.7% betaine. Each dietary treatment consisted of three replicates (n=10/replicate), and the experiment was continued for 16weeks. By the end of the experiment, spleen and intestine specimens were collected from 15 fish (n=5/replicate) for histopathological assessment. The results were statistically analysed using GLM procedures of SAS 9.4. Feed efficiency increased in both POS-B and FM-B groups (p=0.01), while body weight and body weight gain showed only weak tendencies towards an increase (p=0.10 and 0.12, respectively). The villi length was the highest in POS-B fed group (p<0.01). In addition, melanomacrophage centres of the spleen increased in both betaine-supplemented groups (p<0.01). From our findings, we conclude that betaine supplementation with poultry offal silage improved production performance and immune status of Nile tilapia fish.

Histological features of the spleen and pancreas of the Egyptian Nile monitor lizard (Varanus niloticus)

The present study investigated the histological features of the spleen and pancreas of the Egyptian Nile monitor lizard (Varanus niloticus). After gross observations the representative samples were collected from three adult male monitor lizards and were processed for histological examination. Grossly, the spleen was brownish in color and embedded in the mesentery near the stomach and pancreas. The pancreas was yellowish in color and consisted of a ventrally placed principal lobe which was pyramidal and extended in the mesentery, whereas the dorsally located splenic lobe was small and was attached to the spleen. a single duct was emerged from the pancreas. Histologically, the spleen was nodular and was encapsulated by the connective tissue capsule covered by mesothelium. it was composed of white and red pulps. Many ellipsoids, melano-macrophage centers, periarterial and periellipsoidal lymphatic sheaths (PALS and PELS; respectively) were observed. The pancreas demonstrated a thicker capsule covered by mesothelium and the exocrine portion was formed of tubule-acinar cells. Main pancreatic duct passed across the length of the pancreas and was lined by stratified cuboidal epithelium. The Islets were found in the ventral lobe where it was in various sizes. This is the first report about the histological structure of the spleen and pancreas of the Egyptian Nile monitor lizard, where the spleen showed a unique structure while the pancreas was similar to what was described in other varanus species. The information in this study will be a baseline knowledge for future studies regarding endocrine or immune organs in this species.

Histopathology of Brain and Spleen of Freshwater Teleost Anabas testudineus (Bloch, 1792) Induced by Organochlorine Insecticide Endosulfan

Endosulfan is an important environmental pollutant that is a pesticide of organochlorine. The 24, 48, 72 and 96h median lethal concentrations of endosulfan (35 EC) were assessed by an acute static renewal test. The sublethal concentration taken for the present study is one-tenth of the 96h LC50 and fish were exposed to that concentration (1.69 ppb) for 30 days. The histopathological observations revealed the presence of catecholamine neurons in the optic tectum and severe depletion of the layer stratum grisum periventricular. An altered pattern of neurons as an “interrupted string of pearls” was noticed in the posterior tuberal nucleus. From the present study, we could conclude that endosulfan is a serious toxicant that even affects the vital organs like the brain of vertebrates. Histology of the spleen showed necrosis in red pulp, hyperplasia and exudate in white pulp and an increased number of melanomacrophage centers (MMC) of the exposed fish species. Based on the results of this study, it is concluded that endosulfan is highly toxic to edible freshwater fish Anabas testudineus. Subsequently, damage to the structures of cells and tissues and histopathology of target organs comprise a significant parameter to be considered in evaluating the toxic possibility of contaminations on living organisms in various environmental conditions and represent the time exposure to which organisms are subjected.

Biomarker-assisted assessment of aquatic health using the cosmopolitan common carp, Cyprinus carpio (L): a case study of bisphenol-A exposures.

Monitoring aquatic health from environmental pollutants is critical, none more so than bisphenol-A (BPA), a ubiquitous endocrine-disrupting chemical (EDC). The present study brings out the responses of selected transcripts, hormone levels, and tissue histomorphology in a widely distributed fish species Cyprinus carpio (Linn.), following exposure to environmentally relevant (10, 100 ng/L) and higher (1000 ng/L) concentration of BPA. The response of cyp19a1a, cyp19a1b, and c3 significantly decreased, while that of vtg increased in their respective tissue domains. The hematological parameters TEC, Hb, and Hct decreased significantly in contrast to TLC (p < 0.05) at all exposure concentrations, whereas none of the erythrocytic indices (MCV, MCH, and MCHC) was perturbed. The steroidogenic hormone levels, such as estradiol and progesterone, increased significantly with increasing BPA concentrations. In contrast, the testosterone and all the thyroid hormones (T3, T4, and TSH) were suppressed significantly (p < 0.05). At the histological level, the BPA induced chondrocyte proliferation, which was accompanied by hemorrhage of the gill lamellae, increased melanomacrophagic centers (MMCs), and degeneration of tubules and fluid accumulation in the kidney. In parallel, binucleated hepatocytes and inflammations were prominent in the liver. Collectively, the histomorphology confirmed induction of degenerative effects in all the tissues investigated, while the cyclic responses of biochemical markers suggest an ability to regulate the impacts. However, a chronic exposure could result in overriding the endemic reproductive pathways with potential population-level effects. In conclusion, the study identified multiple molecular, cellular, and physiological markers that could be employed to detect early signs of BPA and more broadly EDC exposures. These markers in combination with a wide distribution of C. carpio should allow comparative studies of pollutants at environmental concentrations.

Immuno-pathological changes in Indian catfish Clarias magur (Hamilton, 1822) upon experimental challenge with Aeromonas hydropila

Motile Aeromonas septicaemia (MAS), caused by Aeromonas hydrophila, is one of the most significant problem among the bacterial diseases responsible for causing mortality in catfishes. The objective this study was to understand the modulation of innate immune parameters and histopathological alteration in Indian catfish Clarias magur (Hamilton, 1822), following intraperitoneal injection with A. hydrophila. At 3 to 8 h post-infection (hpi), respiratory burst activity, myeloperoxidase, protease, total anti-protease and α2 macroglobulin increased significantly (p<0.05) indicating immune response of host against pathogen invasion at an early stage of infection. The total protein, albumin, albumin/globulin ratio and bactericidal activity were significantly decreased indicating the response of pathogen to suppress host immune response to establish infection. Serum bactericidal activity, bacterial agglutination titre and lysozyme activity increased significantly at 24 hpi. Histopathological examination of infected fish revealed the accumulation of melanomacrophage centres, congestion, hepatocyte degeneration and vacuolated hepatocytes of liver; hyaline droplet accumulation, lymphocytes infiltration and diffuse necrosis of renal tubule in kidney; unilateral fusion of secondary gill lamellae, leukocytic infiltration as well as dilated central venous sinus in gills. Knowledge regarding the immune response in magur could be useful for developing strategies for improving disease resistance against A. hydrophila infection. Keywords: Aeromonas hydrophila, Histopathological alterations, Indian catfish, Innate immune parameters, Intraperitoneal challenge

Monitoring of reproductive health in the striped catfish Pangasianodon hypophthalmus (Sauvage, 1878) from the Saen Saep Canal, Thailand

Khlong Saen Saep is one of the most important and large canal systems in Bangkok, Thailand. However, the emergence of heavily polluted water has occasionally been reported due to the domestic sewage and industrial effluents discharged into the system. This situation may affect the reproductive status of aquatic lives residing in this canal. To evaluate the reproductive status of the canal inhabitant, the striped catfish Pangasianodon hypophthalmus (Sauvage, 1878)—a common dweller of the Saen Saep Canal—was collected from two selected stations, the Bumpen Nua Temple and the Kamalun Islam Mosque. The fish gonads were then anatomically and histologically examined. The results indicated that neither parasites nor ovary with external abnormality were found. Nevertheless, several histological alterations were detected, including vacuolar degeneration of previtellogenic oocytes, accumulation of melanomacrophage centers (MMCs), and atretic oocytes. Moreover, severe histopathological changes, such as the eosinophilic cytoplasm of spermatogonia, MMCs, blood congestion, and syncytium of spermatozoa, were observed in the fish testis. Our study suggested that the environmental stress and pollutions previously reported from the Saen Saep Canal possibly underpin the gonadal impairments of P. hypophthalmus examined and may have adverse impact on the reproductive health of others living in this canal system

The Use of Hematological and Histopathological Biomarkers to Assess the Health of Aquatic Ecosystems in Koh Sichang, Thailand

Abstract Koh Sichang area in Thailand is a sink for a wide variety of contaminants such as heavily polluted water from industry and oil spills. This situation may affect the health status of fish living in the area, but such information remains scarce. In this study, we evaluated the health status of java rabbitfish Siganus javus, an important marine fish in Koh Sichang, using hematological and histopathological biomarkers. All fish samples were collected from the Koh Sichang area during December 2017 and January 2018. Although the salinity, pH, and dissolved oxygen levels at sampling points were all within the normal range, abnormal nuclei were observed in erythrocytes (up to ~6% of all erythrocytes) and in some leucocytes (neutrophil, lymphocyte and monocyte). Visceral organs (gill, kidney and liver) were apparently normal in terms of gross morphology, but a wide variety of the histopathological alterations were found at the microscopic level: epithelial hyperplasia and aneurysm in gills; blood congestion and melanomacrophage centers (MMCs) in the liver; renal degeneration, granuloma and MMCs together with unidentified parasites in kidney. Calculation of semi-quantitative parameters [histological alteration index (HAI) and the average value of alteration (AVA)] demonstrated the highest frequency of histopathological alterations in kidney, suggesting that kidney is a sensitive organ. Overall, our observations suggest that S. javus in Koh Sichang is under the pathological state and warrants conservation efforts. Keywords: Erythrocytes, Fish Health, Hematology, Histopathology, Kidney

Splenic and renal melanomacrophage centers in shorthorn sculpins (Myoxocephalus scorpius) in Nuuk harbor, West Greenland

Splenic and renal melanomacrophage centers in shorthorn sculpins (Myoxocephalus scorpius) in Nuuk harbor, West Greenland

Aggregation of hepatic melanomacrophage centers in S. herzbergii (Pisces, Ariidae) as indicators of environmental change and well-being

ABSTRACT The melanomacrophage centers (MMCs) in the liver of fish are indicators of environmental conditions, as they are involved in xenobiotic biotransformation. The objective of this study was to evaluate the number of MMC in the liver of juveniles and adults of Sciades herzbergii from areas with different levels of contamination. The fish were caught at three points (reference - A1, potentially impacted - A2 and contaminated - A3), in São José bay (Maranhão, Brazil), in four samples. The livers were subjected to the standard histological procedure and 5μm sections were stained with hematoxylin-eosin. In livers of A2 adult individuals (260.50±161.50 MMCs / mm²) they presented a greater number of MMCs when compared to A3 adults (60.00 ± 30.10 MMCs / mm²). Juveniles showed considerable values in A1 (100.00 ± 0.00 MMCs/mm²) and A2 (95.33 ± 33.00 MMCs / mm²) compared to juveniles in A3 (49.00±0.00 MMCs/mm²). These high values are unexpected for young people. The average number of MMC correlated with the rainy season in the region. The use of hepatic MMCs as a biomarker of exposure to pollutants, in particular substances from fisheries systems, such as ammonia and nitrite, proved to be adequate to differentiate areas with different levels of impacts.

Modulation of immunity and hepatic antioxidant defense by corticosteroids in pacu (Piaractus mesopotamicus)

We investigated the impact of both the oral administration of hydrocortisone (HC) and an acute stressor on stress, innate immune responses and antioxidant system/oxidative stress responses of juvenile Piaractus mesopotamicus. Fish were either 1) given a commercial feed (C), 2) given a feed supplemented with 400 mg/kg HC, or 3) fed a commercial feed, chased for 2 min and exposed to air for 4 min (S). After initial sampling, fish C and HC were fed and sampled 1, 3, 6, 24 and 72 h post-feeding. Fish S were fed at the same time as the other groups, exposed to a stressor, and sampled 1, 3, 6, 24 and 72 h after. Exposure to the stressor increased circulating glucose and cortisol levels (at 1 and 3 h, respectively), while oral HC increased circulating cortisol at 1 h and glucose at 3 h. The stressor activated respiratory activity of leukocytes (RAL) at 3 h and reduced it at 6 h. HC did not activate RAL, but it did impair it at 6 h. The serum hemolytic activity of the complement system (HAC50) was impaired by the stressor at 1 and 3 h and by HC at 1 h. Regarding the antioxidant system, exposure to the stressor reduced glutathione peroxidase (GPx) and catalase (CAT) activity and decreased concentrations of reduced glutathione (GSH) in the liver up to 6 h. HC only impaired GPx. Additionally, stress induced the accumulation of melano-macrophage (MM) and melano-macrophage centers (MMC), which are biomarkers of oxidative stress, in the spleen. Differences in biomarkers in fish given cortisol and exposed to stress indicate that exogenous hormone was unable to precisely reproduce stress responses.

Melanomacrophage Centers in Nile Tilapia (Oreochromis niloticus L.) as Biomarker for Carbamate Exposure

Melanomacrophage centers are aggregates of pigment-containing cells found in the animal’s hematopoietic tissues. Changes in its characteristics have been used to assess the influence of pesticide exposure, and as tools for potential monitoring for fish and environmental health. This study aimed to evaluate the pesticide-induced hepatic and splenic melanomacrophage center responses in Nile tilapia (Oreochromis niloticus L.) following exposure to fenobucarb in varying lengths of exposure. Five test groups were exposed to constant dose of fenobucarb at 0.08 mg L-1at different periods (0, 7, 14, 21, and 28 days). Fenobucarb only induced significant changes in the splenic melanomacrophage centers. Splenic melanomacrophage centers significantly increased in number in response to the increasing lengths of exposure. Increasing trend of size and cover was also observed, however, significant difference was only detected at 28 days exposure period. Significant difference in hemosiderin and lipofuscin pigments was also detected at 28 days exposure which suggests tissue destruction after prolonged exposure. This study confirms the potential of melanomacrophage centers as a sensitive biomarker for fenobucarb exposure indicated by the changes in its characteristics, particularly in the spleen.

Histology of some major immune system organs in Lake Van fish Alburnus tarichi (Güldenstädt, 1814) (Cyprinidae).

The teleostean immune system is variable between and within taxa in terms of morphology. Accordingly, in the current study, the histology of some immune organs (thymus, kidney and spleen) of Lake Van fish (Alburnus tarichi) was investigated. For this purpose, the tissues from eight mature fish were fixed and embedded in paraffin wax, and then the sections were stained with haematoxylin and eosin, Mallory's triple, periodic acid-Schiff and Alcian blue (pH of 2.5) for histologic examinations. In the thymus, no clear discrimination of the cortex and medulla was observed. Lymphoid cells within a reticulo-epithelial network were the predominant cell type in the thymus. The other components in the thymus were macrophages and myoid, mast-like, plasma-like, cystic cells, Hassall's corpuscles, and single or multiple epithelial cystic structures. In the kidney, the head kidney, a major haematopoietic site, consisted of lymphoid and non-lymphoid zones within a reticular network. Cells exhibiting mitotic figures were also detected in the haematopoietic tissue of the head kidney. Haematopoietic tissue was also found in the trunk kidney dispersed amongst the excretory components. The spleen was composed of red and white pulp. The red pulp comprised abundant erythrocytes, whilst the white pulp contained leucocytes with a reticular network. Ellipsoids were also determined in the white pulp. Melanomacrophage centres were found in all of the examined lymphoid tissues of the fish. These findings, which were reported, herein, for the first time will provide reference knowledge for future studies of this anadromous fish.

Use of biomarkers in monitoring pollution status of urban rivers, Limpopo, South Africa.

This study investigated the use of enzymes and histology as potential biomarkers in Sand and Blood Rivers in Limpopo Province, South Africa. Physico-chemical parameters were analyzed at sites S1, S2, S3, S4, and S5 of the Sand River and sites B1 and B2 of the Blood River. Sites S1 and B1 were selected as the reference sites and located upstream of the Polokwane and Seshego wastewater treatment plants (WWTPs) effluent discharge points, respectively. Water quality parameters assessed were water temperature, dissolved oxygen (DO), biological oxygen demand (BOD), total dissolved solids (TDS), turbidity, ammonia, nitrogen, phosphorus, and pH. Sites downstream the WWTPs recorded elevated levels of nitrogen, phosphorus, and ammonia. DO, ammonia, nitrogen, and phosphorus were above the targeted water quality range (TWQR) for aquatic ecosystems. The Canadian council of ministers of the environment water quality index (CCME WQI) showed that the reference sites had good water condition while sites downstream (S2, B2, S3, and S4) had poor water condition. Acetylcholinesterase (AChE) enzyme activity in the brain of Clarias gariepinus from sites downstream was lower than those from sites upstream of the effluent discharge points. The liver of Clarias gariepinus from sites downstream showed higher lactate dehydrogenase (LDH) enzyme activity compared to fish caught at the reference sites. Furthermore, Clarias gariepinus from sites downstream showed a number of histological alterations in gills and liver than fish from upstream. Histological alterations observed in gills included fusion of the secondary lamellae, hyperplasia of the interlamellar, epithelial lifting of secondary lamellae, and hyperplasia of the secondary lamellae. In the liver, histological alterations observed included melanomacrophage centers (MMCs), macrovesicular steatosis, sinusoid congested with kupffer cells, nuclei pleomorphism, and vacuolation. The gill and liver indices were significantly lower at the reference sites compared to sites downstream. Evidently, AChE, LDH, and gill and liver histology can be used as early warning signs of aquatic degradation in rivers that are recipients of poorly treated sewage effluent.

Immunogenicity in Oreochromis niloticus vaccinated with sonicated antigens against streptococcosis

Streptococcosis causes great economic losses in intensive culture of tilapia. Vaccination is the most effective and safest way to tackle infectious diseases. Thus, this study sought the more effective and safer antigenic fraction after sonication of Streptococcus agalactiae to elaborate a vaccine against streptococcosis in Nile tilapia. For this, twenty-one days after vaccination with different fractions (soluble and insoluble) of S. agalactiae, the fish were challenged with the homologous strain (LD50). Then, samples were taken at zero, 14, 28, 60 and 90 days post-vaccination (DPV, n = 7). Blood and organs (cranial kidney, spleen and liver) were collected from vaccinated and unvaccinated fish. Finally, insoluble fraction vaccine presented the best effect, resulting in a 100% relative percent of survival (RPS) and without clinical manifestations. In view of the results, it was to evaluate the role of the insoluble fraction of the antigen in the protective immunity against streptococcosis. The results indicate that the spleen might be the main organ in the vaccine response in Nile tilapia due to the great morphological and immunological differences in vaccinated fish, evidenced by the greater of melanomacrophage centers (MMC) and IgM + lymphocytes in relation to the non-vaccinated fish. At 60 DPV, it was observed the peak of the protective immunity related to the maximum concentration of proteins, circulating leukocytes, antibody titers in the serum and tissue changes with greater expression of IgM + and MMC number in the spleen and kidney of Oreochromis niloticus. Vaccination with insoluble fraction of S. agalactiae was safe and provided effective protection against streptococcosis with maximum protective response at 60 DPV.

Innate Immune Response to Fasting and Refeeding in the Zebrafish Kidney.

Animals acquire nutrients and energy through feeding to achieve a balance between growth and organismal health. When there is a change in nutrient acquisition, the state of growth changes and may also cause changes in the intrinsic immune system. Compensatory growth (CG), a specific growth phenomenon, involves the question of whether changes in growth can be accompanied by changes in innate immunity. The zebrafish (Danio rerio), a well-known fish model organism, can serve as a suitable model. In this study, the zebrafish underwent 3 weeks of fasting and refeeding for 3 to 7 day periods. It was found that CG could be achieved in zebrafish. Zebrafish susceptibility to Streptococcus agalactiae increased after starvation. In addition, the amount of melano-macrophage centers increased after fasting and the proportion of injured tubules increased after refeeding for 3 and 5 days, respectively. Furthermore, the kidneys of zebrafish suffering from starvation were under oxidative stress, and the activity of several antioxidant enzymes increased after starvation, including catalase, glutathione peroxidases and superoxide dismutase. Innate immune parameters were influenced by starvation. Additionally, the activity of alkaline phosphatase and lysozyme increased after starvation. The mRNA expression of immune-related genes like il-1β was elevated to a different extent after fasting with or without lipopolysaccharides (LPS) challenge. This study showed that the function of the innate immune system in zebrafish could be influenced by nutrition status.

Uncovering the first occurrence of Tilapia parvovirus in Thailand in tilapia during co-infection with Tilapia tilapinevirus.

The recently discovered Tilapia parvovirus (TiPV) was the first Parvovirus confirmed to infect fish, causing mortality outbreaks in farmed adult Nile tilapia in China. Severe mortality outbreaks caused by Tilapia tilapinevirus (TiLV) to farmed tilapia in Thailand revealed the concomitant occurrence of TiPV. Out of ten fish farms screened, TiPV was detected in one site rearing juvenile red hybrid tilapia. Clinical signs included abnormal swimming, scale protrusion, skin and muscle haemorrhaging, exophthalmia and generalized anaemia. Histological findings showed extensive infiltration of lymphocytes, with increased melanomacrophage centres in the anterior kidney and spleen, erythrocyte depletion in the spleen and hepatic syncytial cells. Both TiLV and TiPV were systemically distributed in the body of moribund fish. The analysis of the near-complete TiPV genome isolated from Thailand revealed 98.74% sequence identity to the formerly isolated from China, together with a highly conserved and comparable genomic organization and with a 3 nucleotides deletion in the 5-UTR. The viral genome structure was highly conserved for each of its components, with nucleotide and amino acid identity ranging from 100% for ORF1 to 97% for ORF2, and with conserved HuH and Walker loop motifs within NS1. Taken together, our results document the first detection of TiPV outside China, thus for the first time in Thailand. Moreover, TiPV was detected for the first time during a natural occurrence in farmed red hybrid tilapia and involved in co-infection pattern with TiLV. Diagnostic investigations during tilapia disease outbreaks should include the screening for TiPV. Further studies are needed to elucidate TiPV genomic variance, pathobiology, including focussing on the outcomes of TiLV-TiPV co-infection patterns, necessary to enable risk assessment for the worldwide spreading of TiPV and to design adequate control measures against these emerging viruses in tilapia.

Histopathological study of Channa gachua exposed to sublethal concentration of malathion

This is well established fact that the exposure of pesticide leads to the significant physiological and histological changes in aquatic fauna. Therefore, ecotoxicology and histopathology have become the important areas of research for scientists, now a days. In order to investigate histopathological effects of synthetic pyrethroids, Skin, Liver, kidney, gills, and spleen of Channa gachua were examined after exposure to sublethal and acute concentration of melathion (0.8 and 1.6 mg/L) for 20 days. Fishes showed degenerative, necrotic changes and congestion of blood vessels in gill filament. Severe degeneration in secondary gill lamellae, separation of gill filament from basement membrane, proliferation of mucus cells and atrophy of gill filament were seen. Hyperplasia was found as an increased number of epithelial cells at the distal or basal portions of kidney. Few nephrons had obstructed glomerular capillary and detachment of the tubular epithelium with the surrounding tissue. Necrosis was present in hematopoietic tissue, glomerular cells, and tubular cells. Melanomacrophage centers (MMC) were scattered throughout liver and spleen. Exudates and necrosis in the splenic white pulp were observed. The liver had a low number of necrotic hepatocytes and enlarged hepatic perisinusoidal areas containing eosinophilic material. Vacuolar dystrophy of hepatocytes and hypertrophy of hepatocytes were also observed. Fish showed serious skin lesions but did not show any behavioural abnormality as compared to controlled group. Their histological recovery was also examined for next 30 days. These changes which observed during exposure were reversed after 30 days of recovery period.