Gills Of Tilapia Research Articles

Deteksi Koi Herpesvirus (KHV) pada Ikan Nila (Oreochromis niloticus) yang Diinfeksi secara Buatan <Br><I>[ Detection of Koi Herpesvirus (KHV) in Nile Tilapia (Oreochromis niloticus) Infected by Artificially Infection ]<I>

Abstract Koi Herpesvirus (KHV) was formerly known as Cyprinid herpesvirus-3 (CyHV-3) and carp nephritis interstitial and necrosis gill virus (CNGV) is a virus that infects common carp and koi (Cyprinus carpio and C. carpio koi) in farmed and wild population. KHV cause disease at a temperature of 18-25 °C with mortality rate of 80-90 % in fry and adult fish. Currently KHV also detected in tilapia from the results of monitoring in the field. The presence of KHV in tilapia can occur as a result of maintenance in cages adjacent to the infected carp. KHV diagnostic method currently based on case definition and PCR (Polymerase Chain Reaction) detection. The basic concept of PCR is one DNA molecule is used to produce two copies, then four, then eight and so forth through multiplication by polymerase. PCR results sometimes indicated the presence of a faint band caused a low amount of virus, so it is necessary to investigate the presence of KHV DNA in tilapia using different doses of infection. This study aimed to determine the KHV infectivity in nile tilapia were infected by artificially infection and determine dose KHV infection that can infect nile tilapia. The study design used true experimental with with the presentation of descriptive data. Dose of viral infection are 1 ID50, 10 ID50, 100 ID50 and 1000 ID50. The results showed that no clinical symptoms of KHV infected in nile tilapia. The results of electrophoresis of PCR products showed that the mucus of nile tilapia were infected with a 1000 ID50 immersion dose showed thin bands. The same results are also shown in the gill of nile tilapia infected by gill spray at 1000 ID50 dose. Fish were infected by injection, KHV was not detected in mucus, gill, kidney and liver. The results above show nile tilapia cannot be infected by KHV on various treatment

Seasonal determination of heavy metals in muscle, gill and liver tissues of Nile tilapia,Oreochromis niloticus(Linnaeus, 1758) from the tributary of the Ganga River, India

Aquatic biota is contaminated with heavy metals as a result of anthropogenic activities and industrialization. Heavy metals, that is copper (Cu), chromium (Cr), lead (Pb) and zinc (Zn), were analysed in Oreochromis niloticus collected from the Gomti River at Lucknow and Jaunpur sites, India, from 2011 to 2012. Accumulation of heavy metals was estimated in different tissues of tilapia. At both study sites (Lucknow and Jaunpur), metal accumulation in different tissues of this fish was found to be in the following order: Zn > Pb > Cr > Cu in muscles, Zn > Pb > Cr > Cu in gills and Pb > Cr > Cu > Zn in liver. However, it was established that the level of heavy metals in all fish organs at the Lucknow site (except Pb and Zn in gills) was higher. The determined bioconcentration factor of heavy metals in different fish organs at the Lucknow site was as follows: Cu (26.5), Cr (38.33), Pb (52.33), Zn (23.41) in muscles, Cu (36.5), Cr (56.33), Pb (95.66) and Zn (31.66) in gills and Cu (381.50), Cr (367.33), Pb (410...

The role of osmotic stress transcription factor 1 in fishes.

Osmotic stress transcription factor 1 (Ostf1) was first discovered by subtractive hybridization in the gills of Mozambique tilapia (Oreochromis mossambicus) transferred from fresh water (FW) to seawater (SW). It is a putative transcriptional regulator and the “early hyperosmotic regulated protein”. In the 2 hours after FW to SW transfer, ostf1 mRNA levels increase six fold. It is believed that, as a fast-response gene, Ostf1 plays a critical role in fish osmoregulation. Since its discovery, numerous studies have been performed to understand the nature and osmoregulatory mechanism of Ostf1. A decade has passed since the discovery of Ostf1, and it is a good time to summarize our current understanding of this gene. Different fish models have been used to study Ostf1, which is not limited to the traditional euryhaline fishes, such as eels and tilapia. Ostf1 can be found in modern fish models such as medaka and zebrafish. This review covers and summarizes the findings from different fishes, and provides a perspective for future Ostf1 studies.

Identifikasi Koi Herpesvirus pada Dosis yang Berbeda dengan Metode Imunohistokimia Streptavidin Biotin pada Ikan Nila (Oreochromis niloticus) <br><i>[Identification of Koi Herpes Virus At Different Dose with Streptavidin Biotin Methods Immunohistochemistry on Tilapia (Oreochromis niloticus)]<i>

Abstract KHV is a viral disease in goldfish and Koi Fish (Cyprinus carpio) is a highly contagious, infecting all ages or sizes of fish and aquaculture systems. This disease results in mortality between 80% - 100% of the total fish population, with an incubation period of between 1-7 days. KHV infection triggered by a drop in ambient temperature so it is referred to as a virus that attacks when cold (a cold virus). The disease attacks the temperature range of 18-28 ° C and can cause death. This virus attacks can occur at any age of the fish ranging in size from the seed to the parent. The most prominent clinical symptoms due to KHV infection is the sudden death 1-2 days after infection. Other clinical symptoms are necrosis of the gills, sunken eyes, bleeding at the gills, hemorraghe, excess mucus production in the body, and secondary bacterial infections or parasitic infestations. Streptavidin biotin immunohistochemical method was applied to the study of cells and tissues by staining imunostaining. Technique of determining the existence of (location) antigen (target protein) in tissue using antigen-antibody reaction that begins with histotenik procedure is the procedure of making tissue sections (histology). This method has high sensitivity and fast so that it can be applied to the detection of KHV antigen in tissues of fish Tilapia (Orechromis niloticus). This study aims to determine the presence of KHV antigen in tilapia gills after infection. The method used in this study is the experimental method. Dose of virus titer used was 1 ID50, ID50 10, 100 ID50, ID50 1000. The results showed that the Streptavidin Biotin immunohistochemical examination imunopatologi able to detect KHV virus Ag in the gill tissue of tilapia (Oreochromis niloticus) were infected with different doses. In all treatments showed on all the gills are KHV antigen is indicated by the presence of a golden brown color on the gill epithelium. Advised Streptavidin biotin immunohistochemistry test was applied to the detection of the presence or absence of fish-carp KHV carrier as a routine control program and control, including the prevention and outbreak of KHV in Indonesia, because of KHV were attacked in tilapia was persistent and did not show clinical symptoms

Gene expression and cellular localization of ROMKs in the gills and kidney of Mozambique tilapia acclimated to fresh water with high potassium concentration.

Regulation of plasma K(+) levels in narrow ranges is vital to vertebrate animals. Since seawater (SW) teleosts are loaded with excess K(+), they constantly excrete K(+) from the gills. However, the K(+) regulatory mechanisms in freshwater (FW)-acclimated teleosts are still unclear. We aimed to identify the possible K(+) regulatory mechanisms in the gills and kidney, the two major osmoregulatory organs, of FW-acclimated Mozambique tilapia (Oreochromis mossambicus). As a potential molecular candidate for renal K(+) handling, a putative renal outer medullary K(+) channel (ROMK) was cloned from the tilapia kidney and tentatively named "ROMKb"; another ROMK previously cloned from the tilapia gills was thus renamed "ROMKa". The fish were acclimated to control FW or to high-K(+) (H-K) FW for 1 wk, and we assessed physiological responses of tilapia to H-K treatment. As a result, urinary K(+) levels were slightly higher in H-K fish, implying a role of the kidney in K(+) excretion. However, the mRNA expression levels of both ROMKa and ROMKb were very low in the kidney, while that of K(+)/Cl(-) cotransporter 1 (KCC1) was robust. In the gills, ROMKa mRNA was markedly upregulated in H-K fish. Immunofluorescence staining showed that branchial ROMKa was expressed at the apical membrane of type I and type III ionocytes, and the ROMKa immunosignals were more intense in H-K fish than in control fish. The present study suggests that branchial ROMKa takes a central role for K(+) regulation in FW conditions and that K(+) excretion via the gills is activated irrespective of environmental salinity.

Studi Tentang Pengaruh Limbah Pencemar Terhadap Kandungan Radikal NBebas pada Organ Insang Ikan Nila (Oreochromis Niliticus)

Studies on the effect of heavy metal pollution on the appearance of free radicals in aquatic biota has been done by applying heavy metals Pb, Cd and Hg in tilapia fish (Oreochromis Niloticus). Free radicals research was done to organ of tilapia gills using ESR. The result showed that the concentration of Pb Nitrate 0.2 ppm – 1.4 ppm, Cd Nitrate 0.02 ppm – 0.14 ppm and Hg Nitrate 0.006 ppm – 0.018 ppm could improve free radical O 2 - . Free radicals concentration in organ of tilapia gills will increase with increasing concentration of heavy metals.

Effects of salinity on metabolic rate and branchial expression of genes involved in ion transport and metabolism in Mozambique tilapia (Oreochromis mossambicus)

This study investigated the effects of two rearing salinities, and acute salinity transfer, on the energetic costs of osmoregulation and the expression of metabolic and osmoregulatory genes in the gill of Mozambique tilapia. Using automated, intermittent-flow respirometry, measured standard metabolic rates (SMRs) of tilapia reared in seawater (SW, 130mgO2kg−1h−1) were greater than those reared in fresh water (FW, 103mgO2kg−1h−1), when normalized to a common mass of 0.05kg and at 25±1°C. Transfer from FW to 75% SW increased SMR within 18h, to levels similar to SW-reared fish, while transfer from SW to FW decreased SMR to levels similar to FW-reared fish. Branchial gene expression of Na+–K+–2Cl− cotransporter (NKCC), an indicator of SW-type mitochondria-rich (MR) cells, was positively correlated with SMR, while Na+–Cl− cotransporter (NCC), an indicator of FW-type MR cells, was negatively correlated. Principal Components Analysis also revealed that branchial expression of cytochrome c oxidase subunit IV (COX-IV), glycogen phosphorylase (GP), and a putative mitochondrial biogenesis regulator in fish, peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α), were correlated with a higher SMR, plasma osmolality, and environmental salinity, while expression of glycogen synthase (GS), PGC-1β, and nuclear respiratory factor 1 (NRF-1) had negative correlations. These results suggest that the energetic costs of osmoregulation are higher in SW than in FW, which may be related to the salinity-dependent differences in osmoregulatory mechanisms found in the gills of Mozambique tilapia.

Arsenic에 노출된 틸라피아, Oreochromis niloticus의 항산화 효소반응에 미치는 수온의 영향

Department of Aquatic life medicine, Pukyong National University, Busan 608-737The effects of waterborne arsenic (As) exposure on antioxidant defense were studied in liver and gills of tilapia, Oreochromis niloticus under thermal stress. Tilapia were exposed to different As concentrations (0, 200 and 400 μg/L) at three water-temperatures (WT; 20, 25 and 30℃) for 10 days. In antioxidant response, glutathione (GSH) levels, glutathione reductase (GR), glutathione peroxidase (GPx) and glutathione S-treansferase (GST) activities were significantly decreased depend on WT in the gills after As exposure. Also, the range of fluctuation in these enzymes activities was most significantly increased at 30℃ in the liver of tilapia exposed to As. The present findings suggest that a simultaneous stress by temperature change and As exposure could accelerate the alteration in antioxidant enzymes activities of tilapia. Key words: Arsenic, Temperature, Antioxidant enzymes, Oreochromis niloticus

Evaluation of the oxidative status in Oreochromis niloticus fed with tuna by-product meal: possible human health impact

The influence of tuna by-product meal (TBM) diets on the activities of antioxidant enzymes in the muscles, gill and kidney of tilapia was evaluated. The control diet (A0) used fish meal (FM) as the sole source of animal protein and the other three diets (A10-A30), 33%–100% of FM was substituted by TBM at 10% increments. The cytotoxicity of liver and muscles cytosol extracts in human liver cell HepG2 was undertaken. The activities of glutathione S-transferase, superoxide dismutase, catalase and TBARS values in the kidney of fish fed with diet A30 were significantly different (p < 0.05) and no alterations were observed in muscle and gill anti-oxidant activities. Our study has confirmed that the cytosol extract does not exhibit cytotoxic effects on the HepG2 cells. These results indicate that the use of TBM as a total replacement for FM into tilapia diets seems to have oxidative stress, thus generating effect on fish metabolism.

Quantitative label‐free proteomics of tilapia gill epithelium: confirmation of established and identification of novel responses to salinity change (1182.4)

Label‐free quantitative (LFQ) proteomics was employed to analyze effects of salinity stress on the molecular phenotype, i.e. proteome, of gill epithelium in Mozambique tilapia (Oreochromis mossambicus). Fresh water (FW) acclimated tilapia were acclimated to 34 ppt, 70 ppt, and 90 ppt salinity and gill proteins extracted and trypsin‐digested for analysis by LFQ LC‐MS/MS. More than 600 proteins were identified with high identification scores (&gt;85% represented by &gt;5 MS/MS peptides, FDR &lt; 2%). The overall effect of salinity acclimation on protein regulation ratios in gill epithelium (salinity exposed gill epithelia compared to FW handling controls) was found to be proportional to the degree of salinity stress. Salinity‐induced changes in tilapia gill epithelial proteome directly reflected known salinity effects on gills of euryhaline fish, including an increase in the size and number of mitochondria‐rich ionocytes, activities of specific ion transporters, and induction of specific molecular chaperones. Confirming such known effects of salinity on tilapia gill epithelium at the proteome level validated the LFQ workflow. In addition to confirming known salinity stress responses, novel gill proteins involved in salinity acclimation of tilapia, notably protein NDRG1, were identified by this workflow. We propose that protein NDRG1 participates in gill epithelial remodeling during salinity acclimation of euryhaline fish. Moreover, we conclude that LFQ proteomics represents a powerful tool for gaining deep insight into effects of environmental salinity stress on the molecular phenotype of osmoregulatory tissues in euryhaline fish. Supported by NSF grant IOS‐1049780.Grant Funding Source: NSF IOS‐1049780

Cadmium Accumulation in Gill, Liver, Kidney and Muscle Tissues of Common Carp, Cyprinus carpio, and Nile Tilapia, Oreochromis niloticus

Accumulation of cadmium in gill, liver, muscle and kidney tissues of Cyprinus carpio and Oreochromis niloticus were investigated in fish exposed to 0.5ppm cadmium over 1, 15 and 30days under controlled laboratory conditions. Tissue accumulation of the metal was measured using Atomic Absorption Spectrophotometric techniques. Cadmium accumulation in gill, liver, kidney and muscle, tissues of C. carpio and O. niloticus exposed to metal for 1, 15 and 30days increased significantly compared with the control group (p<0.05), except muscle tissue of O. niloticus. A general increase was observed in Cd accumulation with increasing exposure periods. Highest metal accumulation was observed in kidney followed by liver, gill and muscle tissues in both species. Liver accumulation of Cd was higher in C. carpio than O. niloticus, whereas kidney accumulation of the metal was higher in O. niloticus than C. carpio.

Expression of Key Ion Transporters in the Gill and Esophageal-Gastrointestinal Tract of Euryhaline Mozambique Tilapia Oreochromis mossambicus Acclimated to Fresh Water, Seawater and Hypersaline Water

The ability of euryhaline Mozambique tilapia to tolerate extreme environmental salinities makes it an excellent model for investigating iono-regulation. This study aimed to characterize and fill important information gap of the expression levels of key ion transporters for Na+ and Cl− in the gill and esophageal-gastrointestinal tract of Mozambique tilapia acclimated to freshwater (0 ppt), seawater (30 ppt) and hypersaline (70 ppt) environments. Among the seven genes studied, it was found that nkcc2, nkcc1a, cftr, nka-α1 and nka-α3, were more responsive to salinity challenge than nkcc1b and ncc within the investigated tissues. The ncc expression was restricted to gills of freshwater-acclimated fish while nkcc2 expression was restricted to intestinal segments irrespective of salinity challenge. Among the tissues investigated, gill and posterior intestine were found to be highly responsive to salinity changes, followed by anterior and middle intestine. Both esophagus and stomach displayed significant up-regulation of nka-α1 and nka-α3, but not nkcc isoforms and cftr, in hypersaline-acclimated fish suggesting a response to hypersalinity challenge and involvement of other forms of transporters in iono-regulation. Changes in gene expression levels were partly corroborated by immunohistochemical localization of transport proteins. Apical expression of Ncc was found in Nka-immunoreactive cells in freshwater-acclimated gills while Nkcc co-localized with Nka-immunoreactive cells expressing Cftr apically in seawater- and hypersaline-acclimated gills. In the intestine, Nkcc-stained apical brush border was found in Nka-immunoreactive cells at greater levels under hypersaline conditions. These findings provided new insights into the responsiveness of these genes and tissues under hypersalinity challenge, specifically the posterior intestine being vital for salt absorption and iono-osmoregulation in the Mozambique tilapia; its ability to survive in hypersalinity may be in part related to its ability to up-regulate key ion transporters in the posterior intestine. The findings pave the way for future iono-regulatory studies on the Mozambique tilapia esophageal-gastrointestinal tract.

Assessment of Organochlorine Pesticides in Water, Sediment, African Cat fish and Nile tilapia, Consumer Exposure and Human Health Implications, Volta Lake, Ghana

The levels of organochlorine pesticides (OCPs) in water, sediment, Nile Tilapia and African Catfishes were assessed to estimate possible consumer exposures and potential health implications from the Volta Lake, Ghana using gas chromatography equipped with 63Ni electron-capture detector. In agreement with their lipophilic nature, higher levels of OCPs were measured in fish samples than water and sediment samples. Heptachlor was the highest level of OCP measured with concentration of 37.75 ng/g in tilapia gill followed by δ-HCH in tilapia muscle and catfish muscle respectively. All OCP residues in tilapia muscle and catfish muscle did not differ significantly (p<0.05). The highest total OCP load of 66.70 ng/g was measured in tilapia muscle, followed by 63.44 ng/g for tilapia gill. This observation however, contradicts the lipophilic nature of OCPs since the fat content of tilapia gill (14.49%) was five times that of muscle tissues (2.80%). Gill tissues however, may be serving as channels to absorb and distribute OCPs to various fatty tissues in the anatomy and physiology of fish. In water a sample δ-HCH was the highest OCP determined with concentration of 0.669 μg/L. DDT was not detected in both water and sediment samples but was however measured in fish samples. This could be attributed to historical use since DDD and DDE were measured in higher concentrations. From the consumer exposure analysis, the water from the lake is relatively safe for domestic, agricultural and ranching since the acute risk ratio for all detected OCP residues were less than one. The Nile tilapia and African catfishes from this lake are also comparatively safe for human consumption because the estimated dietary intakes from this study are far below the corresponding acceptable dietary intakes for various OCPs. This study therefore shows a declining trend on the environmental burden of OCPs in the middle section of the Volta Lake.

Differential transcriptomic analyses revealed genes and signaling pathways involved in iono-osmoregulation and cellular remodeling in the gills of euryhaline Mozambique tilapia, Oreochromis mossambicus

BackgroundThe Mozambique tilapia Oreochromis mossambicus has the ability to adapt to a broad range of environmental salinities and has long been used for investigating iono-osmoregulation. However, to date most studies have focused mainly on several key molecules or parameters hence yielding a limited perspective of the versatile iono-osmoregulation in the euryhaline fish. This study aimed to capture transcriptome-wide differences between the freshwater- and seawater-acclimated gills of the Mozambique tilapia.ResultsWe have identified over 5000 annotated gene transcripts with high homology (E-value <1.0E-50) to human genes that were differentially expressed in freshwater- and seawater-acclimated gills of the Mozambique tilapia. These putative human homologs were found to be significantly associated with over 50 canonical signaling pathways that are operating in at least 23 biological processes in relation to branchial iono-osmoregulation and cellular remodeling. The analysis revealed multiple signaling pathways in freshwater-acclimated gills acting in concert to maintain cellular homeostasis under hypo-osmotic environment while seawater-acclimated gills abounded with molecular signals to cope with the higher cellular turn-over rate, energetics and iono-regulatory demands under hyper-osmostic stress. Additionally, over 100 transcripts encoding putative inorganic ion transporters/channels were identified, of which several are well established in gill iono-regulation while the remainder are lesser known. We have also validated the expression profiles of 47 representative genes in freshwater- and seawater-acclimated gills, as well as in hypersaline-acclimated (two-fold salinity of seawater) gills. The findings confirmed that many of these responsive genes retained their expression profiles in hypersaline-acclimated gills as in seawater-acclimated gills, although several genes had changed significantly in their expression level/direction in hypersaline-acclimated gills.ConclusionsThis is the first study that has provided an unprecedented transcriptomic-wide perspective of gill iono-osmoregulation since such studies were initiated more than 80 years ago. It has expanded our molecular perspective from a relatively few well-studied molecules to a plethora of gene transcripts and a myriad of canonical signaling pathways driving various biological processes that are operating in gills under hypo-osmotic and hyper-osmotic stresses. These findings would provide insights and resources to fuel future studies on gill iono-osmoregulation and cellular remodeling in response to salinity challenge and acclimation.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2164-15-921) contains supplementary material, which is available to authorized users.

Heavy Metals Concentration in Water, Muscles and Gills of &lt;i&gt;Oreochromis niloticus&lt;/i&gt; Collected from the Sewage-Treated Water and the White Nile

The concentrations of heavy metals (Cd, Cr, Ni, Pb, Cu, Zn, Fe, and Sr) were detected by ICP-OES in muscle tissues and gills of Nile Tilapia (O. niloticus) collected from the effluent of sewage treatment plant, and the released sewage-treated water into the White; and in water samples collected from four station along the sewage treatment plant. The highest concentration of the heavy metal in tissues and gills of was recorded for Sr, followed by Fe, Zn, Cu and Pb, where Sr and Fe recorded higher concentrations in the muscle compared to fish gills. The same trend was found in the other heavy metals. The range of Fe was (10.6 – 11.6 µg/g) in water from sampling stations, with no significant difference between the four stations, while, the level was (2.2 - 3.2 µg/g) in muscle and fish gills. The level of Sr in water was (6.32 – 7.86 µg/g) with increased concentration in station 4, the discharge point of the treated waste-water into the WN; and (2.1 -3.4 µg/g) in muscle and fish gills. The concentration of lead was (0.11 – 0.2 µg/g) in water with the highest level in station 3, the discharge point of industrial effluents and (0.2 – 0.3 µg/g). The level of Zn was (0.5 - 0.9 µg/g) in muscle and fish gills, and (<0.0001 µg/g), but long-term disposal of wastewater into the Nile resulted in high level of Zn and Cu in the tissues and gills of the fish. In conclusion, the levels heavy metals observed in the fish and water samples can be considered as a serious matter of concern as it may be consumed and be harmful to human health in the study area. More safe and economic methods for the elimination of heavy metals from contaminated waters are needed and continuous assessment of the level of pollution of the Nile waters and fish with heavy metals is also necessary.

Quantitative Molecular Phenotyping of Gill Remodeling in a Cichlid Fish Responding to Salinity Stress

A two-tiered label-free quantitative (LFQ) proteomics workflow was used to elucidate how salinity affects the molecular phenotype, i.e. proteome, of gills from a cichlid fish, the euryhaline tilapia (Oreochromis mossambicus). The workflow consists of initial global profiling of relative tryptic peptide abundances in treated versus control samples followed by targeted identification (by MS/MS) and quantitation (by chromatographic peak area integration) of validated peptides for each protein of interest. Fresh water acclimated tilapia were independently exposed in separate experiments to acute short-term (34 ppt) and gradual long-term (70 ppt, 90 ppt) salinity stress followed by molecular phenotyping of the gill proteome. The severity of salinity stress can be deduced with high technical reproducibility from the initial global label-free quantitative profiling step alone at both peptide and protein levels. However, an accurate regulation ratio can only be determined by targeted label-free quantitative profiling because not all peptides used for protein identification are also valid for quantitation. Of the three salinity challenges, gradual acclimation to 90 ppt has the most pronounced effect on gill molecular phenotype. Known salinity effects on tilapia gills, including an increase in the size and number of mitochondria-rich ionocytes, activities of specific ion transporters, and induction of specific molecular chaperones are reflected in the regulation of abundances of the corresponding proteins. Moreover, specific protein isoforms that are responsive to environmental salinity change are resolved and it is revealed that salinity effects on the mitochondrial proteome are nonuniform. Furthermore, protein NDRG1 has been identified as a novel key component of molecular phenotype restructuring during salinity-induced gill remodeling. In conclusion, besides confirming known effects of salinity on gills of euryhaline fish, molecular phenotyping reveals novel insight into proteome changes that underlie the remodeling of tilapia gill epithelium in response to environmental salinity change.

Cadmium, lead and total mercury in Tilapia sp. in Sri Lankan reservoirs

In 2010, samples of muscles, liver and gills of Tilapia (Oreochromis sp.) were collected from eighteen reservoirs of four districts in Sri Lanka: Anuradapuraya, Polonnaruwa (North Central Province), Hambantota (Southern Province) and Ampara (Eastern Province). Cd, Pb and Hg were determined using atomic absorption spectrometry. Mean Cd, Pb and Hg concentrations in muscle were 0.03 mg/kg, 0.06 mg/kg and 0.26 mg/kg, respectively, while gills contained 0.02 mg/kg, 0.44 mg/kg and 0.36 mg/kg, respectively, on a dry weight basis. The amounts of the three metals in liver were 0.30 mg/kg, 2.07 mg/kg and 0.52 mg/kg on a dry weight basis. The results revealed that the level of heavy metal concentration in Tilapia does not exceed the maximum limit for human consumption according to the European Union and Sri Lankan guidelines.

Cyanobacterium producing cylindrospermopsin cause histopathological changes at environmentally relevant concentrations in subchronically exposed tilapia (Oreochromis niloticus)

The acute toxicity of cylindrospermopsin (CYN) has been established in rodents, based on diverse intraperitoneal an oral exposure studies and more recently in fish. But no data have been reported in fish after subchronic exposure to cyanobacterial cells containing this cyanotoxin, so far. In this work, tilapia (Oreochromis niloticus) were exposed by immersion to lyophilized Aphanizomenon ovalisporum cells added to the aquaria using two concentration levels of CYN (10 or 100 μg CYN L(-1)) and deoxy-cylindrospermopsin (deoxy-CYN) (0.46 or 4.6 μg deoxy-CYN L(-1)), during two different exposure times: 7 or 14 d. This is the first study showing damage in the liver, kidney, hearth, intestines, and gills of tilapia after subchronic exposure to cyanobacterial cells at environmental relevant concentrations. The major histological changes observed were degenerative processes and steatosis in the liver, membranous glomerulopathy in the kidney, myofibrolysis and edema in the heart, necrotic enteritis in the gastrointestinal tract, and hyperemic processes in gill lamellae and microhemorrhages. Moreover, these histopathological findings confirm that the extent of damage is related to the CYN concentration and length of exposure. Results from the morphometric study indicated that the average of nuclear diameter of hepatocytes and cross-sections of proximal and distal convoluted tubules are useful to evaluate the damage induced by CYN in the main targets of toxicity.

Cloning and functional characterization of three novel antimicrobial peptides from tilapia (Oreochromis niloticus)

Abstract Antimicrobial peptides constitute an important component of the innate immune system. Teleost fish represent a potentially fruitful resource for novel antimicrobial peptide discovery since these organisms rely significantly on their innate immune systems to combat the constant threat of infections in the aquatic environment. In the present study, we isolated three antimicrobial peptides-like transcripts from tilapia ( Oreochromis niloticus ) gills based on EST reported sequences. These peptides were named oreochromicins (Oreoch-1, Oreoch-2 and Oreoch-3). The cDNA sequences for these putative AMPs encode three pre-pro-peptides with the highest similarity with the members of the piscidin family from teleost fish. The predicted three pre-pro-peptides consist of a signal peptide, a highly cationic mature peptide of 23, 25, and 32 amino acids, respectively and a carboxy terminal pro-domain. The synthetic peptides displayed a broad-spectrum of antimicrobial activity against Gram-negative, Gram-positive bacteria and fungi. These peptides are constitutively expressed in the brain, heart, head kidney, spleen and gut. Additionally, their binding properties to lipopolysaccharide and cytotoxic activity in mammalian and fish cells were assayed.

Salinity-induced activation of the myo-inositol biosynthesis pathway in tilapia gill epithelium

The myo-inositol biosynthesis (MIB) pathway converts glucose-6-phosphate to the compatible osmolyte myo-inositol that protects cells from osmotic stress. Using proteomics, the enzymes that constitute the MIB pathway, myo-inositol phosphate synthase (MIPS) and inositol monophosphatase 1 (IMPA1), are identified in tilapia (Oreochromis mossambicus) gill epithelium. Targeted, quantitative, label-free proteomics reveals that they are both upregulated during salinity stress. Upregulation is stronger when fish are exposed to severe (34 ppt acute and 90 ppt gradual) relative to moderate (70 ppt gradual) salinity stress. IMPA1 always responds more strongly than MIPS, suggesting that MIPS is more stable during salinity stress. MIPS is N-terminally acetylated and the corresponding peptide increases proportionally to MIPS protein, while non-acetylated N-terminal peptide is not detectable, indicating that MIPS acetylation is constitutive and may serve to stabilize the protein. Hyperosmotic induction of MIPS and IMPA1 is confirmed using western blot and real-time qPCR and is much higher at the mRNA than at the protein level. Two distinct MIPS mRNA variants are expressed in the gill, but one is more strongly regulated by salinity than the other. A single MIPS gene is encoded in the tilapia genome whereas the zebrafish genome lacks MIPS entirely. The genome of euryhaline tilapia contains four IMPA genes, two of which are expressed, but only one is salinity regulated in gill epithelium. The genome of stenohaline zebrafish contains a single IMPA gene. We conclude that the MIB pathway represents a major salinity stress coping mechanism that is regulated at multiple levels in euryhaline fish but absent in stenohaline zebrafish.