Blood Of Tilapia Research Articles

Effect of increasing ambient temperature on physiological changes, oxidative stress, nitric oxide, total antioxidant power, and mitochondrial activity of Nile tilapia (Oreochromis niloticus Linn.)

The objective of this study was to investigate the effect of high ambient temperature on physiological changes of live Nile tilapia (Oreochromis niloticus Linn.) and biochemical parameters in Nile tilapia blood cells. Live Nile tilapia and Nile tilapia blood cells were maintained at temperature ranges from 24 to 34 °C and 24–38 °C, respectively. Then, physiological parameters (body temperature, body color score, pulse rate, ventilation rate, oxygen saturation) of the live Nile tilapia and biochemical parameters (total antioxidant power, hydrogen peroxide, malondialdehyde, nitric oxide, and mitochondrial activity) of the Nile tilapia blood cells were measured for every 2 °C increase. It was found that when the ambient temperature increases, body temperature of live Nile tilapia continually increased. Total antioxidant power and hydrogen peroxide, pulse rate, body color score, malondialdehyde, ventilation rate and mitochondrial activity commenced to increase at 26, 28, 30, 32, 34 °C (P < 0.05), respectively. Blood oxygen saturation decreased at 32 °C (P < 0.05). The response of nitric oxide of Nile tilapia blood cells responded to increased temperature in two phases. In the first phase, nitric oxide decreased at 28–32 °C (P < 0.05), then increased and decreased again at a temperature of 38 °C (P < 0.05). These phenomena indicated that when the live Nile tilapias and the Nile tilapia blood cells were exposed to high ambient temperature, they were under heat stress and oxidative stress. In addition, physiological responses in the live Nile tilapia and biochemical changes in their blood cells when exposed to high ambient temperature occurred in a consistent manner when the temperature continually increased.

Impact of polyculture in aquaponics on the hemato-serological and health status of Nile tilapia (Oreochromis niloticus) and carp (Cyprinus carpio)

ABSTRACT Aquaponics is an innovative, eco-friendly, and sustainable food production system that combines hydroponic crop production with recirculating aquaculture. This study aimed to assess the haematological, biochemical, and health status of Nile tilapia and common carp in monoculture and polyculture systems. A total of 800 (Oreochromis niloticus) and (Cyprinus carpio) with an average body weight of 1.1± 0.2 g were used. The fish were divided into three groups: (I) contained Nile tilapia only (monoculture), (II) contained common carp only (monoculture), and (III) contained polycultured tilapia and carp. The results of the study revealed a decrease in red blood cell counts, haemoglobin levels, mean corpuscular haemoglobin concentration, and hematocrit in monoculture tilapia blood, indicating significant differences when compared to polyculture tilapia blood. The biochemical parameters except total protein, glucose, and urea were significantly higher in the blood serum of polyculture carp compared to tilapia. Immunoglobulin variables and lysozyme activity were the same in the blood of fishes, confirming that Nile tilapia and common carp were still fit with a good immunological status under monoculture and polyculture in an aquaponic system. Conclusion: Nile tilapia and common carp cultivated in aquaponic systems (monoculture and polyculture) still fall within the normal range for haematology and biochemistry.

CLINICAL SAFETY OF TREATMENT WITH ZILEUTON, 5-LOX INHIBITOR, DURING ACUTE INFLAMMATORY REACTION IN NILE TILAPIA (Oreochromis niloticus)

Zileuton is an inhibitor of the 5-lipoxygenase enzyme that transforms essential fatty acid (EFA) substrates into leukotrienes (LTB4, LTC4, LTD4 and LTE4), but little is known about the use of this drug in teleost fish. Therefore, the objective of this study was to evaluate the clinical safety of treatments with 2,25 mg and 4,50 mg of zileuton/Kg -1 (bodyweight), administered orally in the diet, through biochemical and hematological analysis during the acute inflammatory reaction in Nile tilapia ( Oreochromis niloticus ), induced by Aeromonas hydrophila bacterins. The study used eighty tilapias, conditioned in 20 tanks (n=4), constituting the following treatments: T0 (control), T1 (2,25 mg zileuton) and T2 (4,50 mg zileuton), being sampled eight animals per treatment in three periods: 6, 24 and 48 hours post-inoculation, and a 10th group consisting of fish without any type of stimulus to obtain the reference values. In order to evaluate and determine the blood count and serum biochemical, it was necessary to collect blood samples. The hematology results of the tilapia treated with zileuton did not reveal alterations between tilapia subjected to different treatments and control fish (T0). The liver cytotoxicity analysis of tilapias treated with zileuton did not reveal significant (p≥0,05) alterations in AST and ALT serum enzymatic activity. The study of tilapia blood total protein showed decrease in the T1 group at 48 HPI. As the treatment time progressed, the results indicated decrease in the serum albumin levels for T2 group at 24 HPI. The determination of serum biochemichal of creatinine, cholesterol, triglycerides, and glucose did not differ statistically between treatments. The results observed in the hematological and biochemical analyzes allows to conclude that zileuton administered orally, at doses of 2,25 and 4,50 mg/Kg -1 (body weight) demonstrated to be clinically safe.

Distribution and localization of Streptococcus agalactiae in different tissues of artificially infected tilapia (Oreochromis niloticus)

China's tilapia industry has the most complete industrial chain in the world, but, in recent years, tilapia streptococcosis have frequently occurred, which has become a bottleneck restricting the development of tilapia industry. Although plenty of studies have been conducted on Streptococcus agalactiae (Group B Streptococcus, GBS) in tilapia, the mechanism of GBS invasion is still unclear. In order to further understand the invasion route, we used the qPCR method to study bacteria load in liver, intestine, gill, spleen, head kidney, kidney, and brain tissues of GIFT tilapia infected by a GBS virulent strain WC1535 at different infection time and the histological method to systematically analyze bacterial distribution and localization in above infected tissue. Through the dynamic analysis of bacteria load, the bacterial copy number of WC1535 reached the peak in each tissue at 24 h post-infection (hpi). Therefore, tissues at 24 hpi were taken as the research object to investigate the distribution and localization of WC1535 by paraffin section and electron microscopy. The results of tissue section showed that WC1535 existed in three forms in blood: free scattering without attachment to any structure, phagocytized by phagocytes (mainly macrophages) and a few red blood cells, and attached to the inner wall of blood vessels. The results of qPCR and tissue section both showed that the density of bacteria in head kidney, spleen and gill was high, at the same time, these tissues had abundant blood and capillaries, so this suggested that the S. agalactiae existed mainly in the blood of tilapia. There were almost no pathogens in the parenchymal cells of each tissue, but the surface of epithelial cells such as vascular endothelial cells and fibroblasts adhered a lot, which indicated that S. agalactiae had epithelial cell affinity. The results of electron microscopy showed that S. agalactiae can survive and proliferate intracellularly after being phagocytosed by macrophages, suggesting that macrophages might play as pathogen carriers or “Trojan horses” to achieve the immune escape, break the blood-brain barrier (BBB), and lead the meningitis in tilapia. Since GBS of tilapia can be internalized by macrophages, antibiotics with strong tissue distribution, cell penetration and good meningeal penetration are recommended for the treatment in the early stage of streptococcosis.

Monitoring of Heavy Metals in Major Drains and Farms at Fayoum Government and Treatment by Pumpkin and Eggplant

This study was carried out in three different farms and drainages at EL-Fayoum Government in Egypt. Five heavy metals (Zn, Cd, Pb, Fe and Cu) were addressed in farms and drain water. The organs (gills, skin, muscles and liver) and blood of selected fish; gathered from various farms and drains, were examined to measure the heavy metals’ residue. The results showed that iron was the most accumulated metal in the three drains and farms, while zinc was the most accumulated metal in the Nile tilapia blood. For water treatment, pumpkin showed high removal of Zn (65%) and Pb (50%), while eggplant gave maximum removal values of Fe, Cd and Cu (88%, 78% and 77%, respectively). In the current study, investigation of some biochemical blood parameters was also determined, such as alanine aminotransferase, aspartate aminotransferase enzyme, urea, creatinine, random blood sugar, creatinine kinase, alkaline phosphatase and thyroid-stimulating hormone, thyroxine and triiodothyronine, growth hormone and cortisol hormones.

The screen herbal immunopotentiator and research on its effect on the innate immune system and disease resistance of Nile tilapia (Oreochromis niloticus) against Streptococcus agalactiae

To screen potential herbal immunopotentiators, the effects of 20 herbal aqueous extracts (HAEs) on the oxygen respiratory burst activity (ORBA) and phagocytic activity of tilapia blood leucocytes were determined using nitroblue tetrazolium (NBT) reduction and phagocytizing latex beads methods, respectively. The screened-out herbal aqueous extract (HAE) supplemented diet (10 g/kg, dry herb/dry feed) was consecutively fed to healthy tilapia for in vivo evaluating its effects on the ORBA and phagocytic activity of head-kidney leucocytes, the acid phosphatase (ACP), lysozyme (LZM), catalase (CAT) and superoxide dismutase (SOD) activities of serum, and the mRNA expression levels of IL-β, IL-8, Hsp70, and TNF-α in the spleen. For evaluating the efficacy of the screened-out HAE on preventing streptococcosis, the tilapia were respectively and consecutively fed the control diet and the screened-out HAE supplemented diet for seven and fourteen days and subsequently infected with Streptococcus agalactiae. Their survival cures were compared using the log-rank test. Additionally, the components in the screened-out HAE were identified using ultra-performance liquid chromatography-Q exactive orbitrap-mass spectrometry (UPLC-QE-MS). Results showed that, among the candidate HAEs, Scutellaria baicalensis HAE showed more ability in terms of simultaneously enhancing the ORBA and phagocytic activity of tilapia blood leucocytes as compared to the other candidate HAEs. Oral administration of S. baicalensis HAE significantly elevated the ORBA and phagocytic activity of head-kidney leucocytes, the ACP, LZM, and SOD activities of sera, the mRNA expression levels of IL-8 and Hsp 70, and the cumulative survival rate of tilapia with S. agalactiae infections. The negative and positive models of UPLC-QE-MS identified 256 and 596 components of S. baicalensis HAE, respectively. Taken together, the results of this study indicate that S. baicalensis HAE could prove useful in the prevention of tilapia streptococcosis and suggest that it could be further developed as immunostimulants.

Assessment of phagocytic activity of tilapia blood cells under hormone-induced stress

Assessment of phagocytic activity of tilapia blood cells under hormone-induced stress

Effect of Squid Powder (Loligo Sp.) On Antibody Titer and Bacteria Density in Blood of Tilapia (Oreochromis niloticus) infected by Aeromonas hydrophila.

Aeromonas hydrophila is bacteria that often infect freshwater fish and causes Motile Aeromonas Septicemia (MAS) disease. One alternative antibacterial that can be used is squid ink ( Loligo sp.) which contains antibacterial substances. The purpose of this study was to determine the effect of squid ink ( Loligo sp.) on antibody titers and bacterial density in tilapia infected with A. hydrophila . This study used a Completely Randomized Design (CRD) with the treatment of squid ink powder in feed at a dose of 52.5 ppm (A), 62.5 ppm (B) and 72.5 ppm (C), positive control (K+) using oxytetracycline ( 20 ppm) on feed and negative control (K-) without giving treatment to feed. The main parameters observed were bacterial density in blood of tilapia ( O. niloticus ) and antibody titer. In addition to the main parameters, supporting parameters observed in this study included survival rate (SR), and measurements of water quality (temperature, DO and pH). The best dose in giving squid ink ( Loligo sp.) powder in feed was 62.5 ppm (treatment B) because it supresing bacterial density in the blood of tilapia ( O. niloticus ) until 166.33 X 10 3 cfu/mL, decreasing antibody titer from 26.67±09.24 % to 13.00±04.62 % and highest survival rate of 90.47%.

СРАВНИТЕЛЬНАЯ ФИЗИОЛОГО-ИММУНОЛОГИЧЕСКАЯ ХАРАКТЕРИСТИКА РЫБ СЕМЕЙСТВА ЦИХЛОВЫЕ И КАРПОВЫЕ

Modern aquaculture is rapidly developing. It includes food fish farming and decorative fish breeding. Like in any fast-growing livestock industry, there may be problems related to the health of fish. Carp is the main object in Russian fish farming, representing the basic type of unpretentious, omnivorous and fast-growing pond polyculture. Tilapia is one of the most preferred species of global aquaculture, due to its hardiness, rapid weight gain and ability to tolerate high planting density. Discus is the most popular of the ornamental fish species; it features a large number of color variations, interesting behavior and is cost-effective in breeding. The authors carried out comparative physiological assessment of bony fish of the cyprinid and cichlid families. Hematological parameters were determined – erythrocyte and leukocyte formulas (by means of differential analysis techniques); biochemical parameters of blood serum (with the analyzer), the average cytochemical coefficient of lysosomal cationic protein content in fish blood neutrophils. The research results showed specific features in the intensity of erythro- and leukopoiesis, the proportion 32 of granular cells of the myeloid series. It was revealed that the peculiarity of discus is the presence of blast forms of white blood cells in the blood: myeloblasts, promyelocytes, and myelocytes. In the blood of tilapia, in contrast to discus and carp, there is a high content of granulocytes: neutrophils, eosinophils and basophils of monocytes and lymphocytes in the leukogram. Differences between species were noted based on the results of the lysosomal cation test. The difference in a number of biochemical parameters can also be seen: in tilapia as compared with other species – in the content of albumins, alkaline phosphatase and ALT, in discus – in the activity of lactate and KK enzymes.

Defensible standardized ploidy assessments for Grass Carp (Ctenopharyngodon idella, Cyprinidae) intercepted from the commercial supply chain

Abstract Although methods are in place through the U.S. Fish and Wildlife (USFWS) program for ploidy testing of feral caught Grass Carp (Ctenopharyngodon idella) and black carp (Mylopharyngodon piceus), no guidelines exist for carp hauled across state lines. Using 1200 Grass Carp purchased by undercover Ohio law enforcement during 2015–2016, we developed a standardized protocol for discriminating ploidy by using two parameters, nuclear size and DNA content. Bead standards at 2 μm or 4 μm were used to establish nuclear size from Nile Tilapia (Oreochromis niloticus), known diploid (n = 20) and triploid (n = 20) Grass Carp blood, and cells derived from eyeballs of purchased field carp. The control for establishing DNA content was cryopreserved or fresh tilapia blood (2.40 pg). Time postmortem indicated nuclear size was similar over 4 days, but DNA quality from triploids was best at 24 h. Occasionally, only size or DNA content was measurable. Tilapia mean nuclear size (n = 501 samples) was 4.61 μm (SE 0.05) (R2 = 0.94). Known diploid and triploid blood nuclear sizes, compared with tilapia size, were 3.62 μm (SE 0.13) (R2 = 0.96) and 7.58 μm (SE 0.27) (R2 = 0.96), respectively. Mean field carp eye nuclear size was 5.83 μm (SE 0.13). Mean DNA content of cells from field carp eyes (n = 698 fish) was 3.51 pg (SE 0.06). No diploid Grass Carp were detected in the USFWS certified triploid Grass Carp transports. This standard protocol reliably discriminates ploidy and can be used for enforcement of regulations that differ among state jurisdictions.

Modulation of innate immunity in Nile tilapia (Oreochromis niloticus) by dietary supplementation of Bacillus subtilis endospores

Dietary supplementation of probiotics is growing as a scientifically valid alternative to antibiotics for enhancement of overall animal health and productivity in aquaculture. Strains of Bacillus subtilis are regarded as attractive probiotic candidates to the fish farming industry; however, there is a limited number of studies focused on the use of specific strains probiotics in tilapia, and therefore complicating replication. The objective of this study was to examine the effect of the strains NZ86 (NRRL B-50136) and O14VRQ (NRRL B-67221) of B. subtilis on various parameters of the innate immunity in Nile tilapia (Oreochromis niloticus) in a 51-day feeding trial. Supplementation of tilapia with either strain resulted in significant increases (p < 0.05) in plasma lysozyme concentration of varying degrees throughout the trial. Meanwhile, alternative complement activity was significantly elevated (p < 0.05) only after feeding of the NZ86 strain after 14 and 51 days. Conversely, supplementation with O14VRQ resulted in a significant increase (p < 0.05) in the percent of neutrophils in the peripheral blood of tilapia by day 28. At the end of the trial, there was a trend towards increased phagocytic and respiratory burst activities observed in immune organ derived leukocytes. Feeding with either probiotic appeared to have an up-regulation on the gene expression of both pro-inflammatory cytokines in the intestine, yet only O14VRQ was significantly different than the control. Moreover, the occurrence of these results could be associated with supplementation of the probiotic strains, given that Bacillus bacteria were observed to populate the intestines of the dietary treatment groups. These results suggest the potential roles of these B. subtilis probiotic candidates to stimulate immune responses both locally and systemically in tilapia.

Microbial biomass as an antioxidant for tilapia feed

Microbial biomass (MB) produced by different industries is thought to be a beneficial supplement in fish feed due to high contents of antioxidants and pigments. However, little is known about their impact on fish health. In this experiment, 960 tilapia (26.84 1.03 g) were fed one of eight experimental diets—a control diet with no MB (C), a control diet with vitamin E (VE) and six diets with three types of MB at two concentrations (0.25% and 0.5%): Rubrivivax gelatinosus (RG25 and RG50), Spirulina platensis (SP25 and SP50) and Saccharomyces cerevisiae (SC25 and SC50). Adding MB to diets decreased plasma total oxidant status, malonaldehyde and leucocyte respiratory burst; increased the total antioxidant status; and did not affect the blood biochemical parameters. In flesh, the use of the MB lowered the thiobarbituric acid-reactive substances and increased redness (except for SC) and carotenoid deposition (except SC25). So, it was concluded that the use of the MB provided an antioxidant effect in tilapia blood plasma, decreased lipid oxidation and increased pigmentation and carotenoid deposition in the fish flesh, without imparting a negative impact on the animals’ health.

Accumulation of humic-like and proteinaceous dissolved organic matter in zero-discharge aquaculture systems as revealed by fluorescence EEM spectroscopy

Recirculating aquaculture systems (RAS), offering many economic and fish husbandry benefits, are characterized by an accumulation of dissolved organic matter (DOM) and, specifically, humic substances (HS). As reported in a number of studies, HS may affect biological activity in both invertebrates and vertebrates. Given the accumulation of HS in RAS, it is therefore of great interest to characterize DOM and, specifically, its HS fraction in the RAS. The present study was aimed at characterizing long-term changes in fluorescent DOM composition in the culture water of RAS systems, which were operated in a novel, zero water exchange mode. Two such zero-discharge recirculating systems (ZDS) were examined: a freshwater system, stocked with hybrid tilapia (Oreochromis aureus x Oreochromis niloticus) and a marine system, stocked with gilthead seabream (Sparus aurata). Excitation-emission matrices (EEMs) of fluorescence, coupled with parallel factor analysis (PARAFAC), were used to characterize and quantify the different DOM components in the ZDS. In the culture water, one tryptophan-like and four HS-like components were identified. The fluorescence intensities of three of the HS-like components as well as the tryptophan-like component increased at comparable rates during ZDS operation while a much slower accumulation of these compounds was observed in a parallel operated, flow-through, freshwater aquarium. The ZDS examined in this study comprised a sludge digestion stage where a considerable accumulation of all fluorescent components was detected. A HS-like components and a tryptophan-like component in blood of tilapia from the freshwater ZDS were similar to components found in the culture water. Blood levels of both components were higher in fish cultured in the DOM-rich ZDS than in fish raised in the control, flow-through freshwater aquarium. Fluorescence of the HS-like component found in the fish blood increased also with time of ZDS operation. The finding that fish blood contains a HS-like fluorescent component may have important implications for the understanding of the physiological effects of HS in fish and the possible benefits of these substances in aquaculture.

GAMBARAN DARAH IKAN NILA (Oreochromis niloticus) DENGAN PENAMBAHAN DOSIS PREBIOTIK YANG BERBEDA DALAM PAKAN

Prebiotics which are non-digestible ingredients that benefit the host by stimulating growth and activity of health promoting bacteria. This research aimed to know blood parameters of tilapia with the addition of different dose of prebiotics in feed. Fish were feed four times daily in ad satiation. The feed used was commercially feed with 32 % carbohydrates, 7 % lipids and 30 % proteins. The prebiotic used was extracted from sweet potato so called sukuh variety. The experiment were done with three treatments and three replicates, namely 0% prebiotic, 1% prebiotic and 2% prebiotic. The result showed that application of prebiotic in feed can promote better tilapia blood parameters and immune system compared to control. The treatment with the addition of 1% prebiotic showed best result to improve leucocyte, lymphocytes and the phagocytic index among other treatments. Keyword: blood parameters, immune system, prebiotic, Tilapia

Construction of a Streptococcus iniae sortase A mutant and evaluation of its potential as an attenuated modified live vaccine in Nile tilapia (Oreochromis niloticus)

Streptococcus iniae is a major Gram-positive aquatic pathogen, which causes invasive diseases in cultured fish worldwide. The identification of potential virulence determinants of streptococcal infections will help to understand and control this disease, but only a few have been confirmed in S. iniae. Sortase A (srtA) is the key enzyme that anchors pre-mature cell wall-attached proteins to peptidoglycan and it can affect the correct positioning of surface proteins, as well as the course of Gram-positive bacterial infection, thereby making it a potential target in the study of virulence factors and disease control. In this study, the 759 bp srtA gene was cloned from pathogenic S. iniae TBY-1 strain and the mutant strain TBY-1ΔsrtA was constructed via allelic exchange mutagenesis. We found that srtA shares high similarities with sortase A from other Streptococcus spp. Direct survival rate assay and challenge experiments were performed, which showed that the mutant strain TBY-1ΔsrtA had a lower survival capacity in healthy tilapia blood and it was less virulent than the wild type strain in tilapia, thereby indicating that the deletion of sortase A affects the virulence and infectious capacity of S. iniae. The mutant strain TBY-1ΔsrtA was used as a live vaccine, which was administered via intraperitoneal injection, and it provided the relative percent survival value of 95.5% in Nile tilapia, thereby demonstrating its high potential as an effective attenuated live vaccine candidate.

Suplementasi β-glucan dari ragi roti (Saccharomyces cerevisiae) dalam pakan terhadap aktivitas fagositosis, aktivitas NBT, total protein plasma dan aktivitas aglutinasi darah ikan nila (Orechromis niloticus)

Abstract. Tilapia is an important fisheries comodity which intesively farmed in Indonesia. However, an intensive farming system of aquatic organism often lead to disease outbreak. Ones the disease emerged, it will be difficult to combat. The curing method by using antibiotics in aquatic organism will bring negative impacts, such as causing bacteria resistance and decline of aquatic environments. Therefore control of disease in aquatic organism should be done through preventive methods such as the use of β-glucan from baker’s yeast (Saccharomyces cerevisiae). It is widely known that yeast’ cell wall contain of immunostimulant substance namely β-glucan. This research was aimed to find the effect of different dose of β-glucan in diet toward the phagocytic activity, respiratory burst which is indicated by Nitroblue Tetrazolium (NBT) activity, total of protein plasm and agglutination activity of tilapia blood. Method used in this study was experiment by complete random design using five treatments triplicate. Those treatments were β-glucan 0; 2,5; 5; 7,5 and 10 ppmkg-1 diet. Result showed that the different dose of β-glucan in diet gave a significantly effect on the phagocytic activity and total of protein plasm, but not on respiratory burst (NBT activity). The highest phagocytic activity occured in treatment E (β-glucan 10 ppmkg-1 diet) with the value of phagocytic activity was 37,67%, whereas the highest of total of protein plasm was occured in treatment B (β-glucan 2,5 ppmkg-1 diet) with the value of 123,58 mgml-1. Keywords : Baker’s yeast, β-glucan, phagocytic and agglutination activity, NBT activity, total of protein plasm

Hemoparasite and hematological parameters in Nile tilapia

The accelerated growth of finfish aquaculture has resulted in a series of health problems, including blood disorders by hemoparasites; there are scarce studies about these agents and their impact in actual intensive farming. The aim of this study was to identify and quantify the hemoparasites present in monocytes and erythrocytes in the blood of tilapia and their correlation with the hematological profile. Blood samples were collected from caudal vessels of 15 cage-reared Nile tilapia (Oreochromis niloticus), with 70 ± 10 g weight on average, from Itambaraca Municipality, Parana State, Brazil. The total red blood cells, mean corpuscular volume, hematocrit, total and differential white blood cells counts, and the number of thrombocytes were determined in blood smears stained with May-Grunwald–Giemsa–Wright and Quick Panoptic. The results showed the presence of pleomorphic cytoplasmic inclusions with corrugated appearance and basophilic staining, mainly in monocytes, suggesting Anaplasmataceae parasitemia and inclusions with the same morphological characteristics in erythrocytes of one Nile tilapia. The hematological analysis showed no significant difference (P < 0.05) between infected and not infected fish, and therefore, there was no correlation between parasitemia and hematological profile. These observations allow us to infer that the intracytoplasmic inclusions in monocytes and erythrocytes are compatible with the family Anaplasmataceae. There was no correlation between the blood profile and low level of parasitemia.

Impact of environmental DDT concentrations on gill adaptation to increased salinity in the tilapia Sarotherodon melanotheron

Estuaries of tropical developing countries suffering from severe droughts induced by climate change are habitats to fish, which face drastic salinity variations and the contact with pollutants. The Western Africa tilapia Sarotherodon melanotheron is highly resistant to hypersalinity, but the effect of human-released xenobiotics on its adaptation is barely known. Controlled experiments were conducted to observe S. melanotheron gill adaptation to abrupt salinity variations in the presence of waterborne DDT, at concentrations detected in their natural habitat. The gills appeared as an important site of DDT conversion to DDD and/or depuration. A 12-days DDT exposure resulted in decreased gill epithelium thickness at all salinities (from fresh- to hypersaline-water), and the structure of gills from freshwater fish was particularly altered, relative to controls. No unbalance in tilapia blood osmolality was observed following DDT exposure, which however caused a decrease in branchial Na+-K+-ATPase (NKA) activity. Gill cellular NKA expression was reduced in salt-water, together with the expression of the CFTR chloride channel in hypersaline water. Although S. melanotheron seems very resistant (especially in seawater) to short-term waterborne DDT contamination, the resulting alterations of the gill tissue, cells and enzymes might affect longer term respiration, toxicant depuration and/or osmoregulation in highly fluctuating salinities.

Inhibition ability of probiotic, &lt;i&gt;Lactococcus lactis&lt;/i&gt;, against &lt;i&gt;A. hydrophila&lt;/i&gt; and study of its immunostimulatory effect in tilapia (&lt;i&gt;Oreochromis niloticus&lt;/i&gt;)

The present study was designed to investigate the inhibition ability of probiotic, Lactococcus lactis RQ516, against A. hydrophila in vitro and its immunostimulatory effect in tilapia, Oreochromis niloticus as growth promoter. Six tanks were used (T-1 and control treated with and without RQ516, respectively) and three replicates per treatment. The inhibition ability assay in vitro showed that the minimum diameter of the inhibition zone (P < 0.05) was 7.43 ± 0.47 mm at 6 h and the final diameter at 24 h was 14.77 ± 1.17 mm. After 40 days, probiotic treatment as water additives significantly improved the final weight and daily weight gain (DWG) (P < 0.05). A significant increase (P < 0.05) in the total protein and globulin concentration of tilapia blood serum could be found in T-1 compared with the control. These immune responses were generally more pronounced with probiotic-treated tilapia. As for immune responses, the higher respiratory burst activity (RBA), lysozyme content (LC), myeloperoxidase (MPO) and superoxide dismutase (SOD) activities were observed in T-1 (P < 0.05) than the control. It indicated that probiotic Lactococcus lactis RQ516 was beneficial for tilapia in terms of increasing final weight, DWG and the concentrations of serum protein and globulin and enhancing immune responses. International Journal of Engineering, Science and Technology, Vol. 2, No. 7, 2010, pp. 73-80

Acute acidic exposure induces p53-mediated oxidative stress and DNA damage in tilapia ( Oreochromis niloticus) blood cells

Acid rain and inputs of acidic effluent can result in increased acidity in aquatic ecosystems, where it is known to have a significant impact and possibly, to cause the decline of some populations of aquatic organisms. In previous studies, intracellular acid-induced oxidative stress has been shown to cause DNA damage, and cooperatively activate the expression of the p53 gene. The acute effects of acidic environments on shrimp and fish have been widely studied. However, the molecular mechanism of acid-induced injury remains largely unknown. In this study, we examined the cellular responses of tilapia to acidic exposure-induced oxidative stress and antioxidant enzyme gene expression. Furthermore, we determined how acute acid stress activates the ATM–p53 signal pathway. We measured the upregulation of reactive oxygen species (ROS) production, the intracellular Ca 2 + concentration ([Ca 2 +] i), the tail DNA values, the malondialdehyde (MDA) level in the blood cells and the percentage of dead and damaged blood cells. Our results suggest that oxidative stress and DNA damage occurred in tilapia in conditions where the pH was 5.3. Apoptosis was detected by Hoechst staining, which was mainly associated with changes in cell viability. The parameters that we measured were related to acid-induced DNA damage, and all parameters changed in the blood cells through time. The effects of acute acid exposure (pH 5.3) on the expression of ATM, p53, p21, Bax, manganese superoxide dismutase (MnSOD), glutathione peroxidase (GPx) were investigated in tilapia blood cells. The results showed that acute acid stress induced upregulation of ATM, p53 and p21, associated with increasing of DNA damage and apoptosis in blood cells. Additionally, the expression of Bax was slightly increased. Moreover, consensus p53-binding sequences were identified in tilapia MnSOD and GPx gene promoter regions and increased levels of ROS in the blood cells coincided with increased mRNA expression of p53, MnSOD and GPx. Therefore, it suggests that acid exposure-induced oxidative stress may cause DNA damage or apoptosis, and cooperatively activate ATM–p53 pathway, which may lead to the activation of p21 and regulate transcription of MnSOD and GPx.