Nile Tilapia Oreochromis Niloticus Research Articles

A produção científica mundial sobre a tecnologia bioflocos na tilapicultura como propulsora do desenvolvimento sustentável

O objetivo deste estudo de revisão foi avaliar a sustentabilidade econômica, social e ambiental da biotecnologia bioflocos no cultivo de tilápia do Nilo Oreochromis niloticus. Com uma revisão sistemática, utilizou-se como metodologia os detalhamentos dos critérios de exclusão e inclusão adotados para a seleção da amostra e análise dos conteúdos das publicações. Os artigos utilizados neste estudo foram pesquisados nas bases Scopus e Web of Science. Foi utilizada a metanálise, optando-se pela natureza mista, ou seja, qualitativa e quantitativa de artigos publicados nas revistas científicas no período de 2008 a 2021. Constatou-se que a avaliação econômica, social e ambiental que contempla o desenvolvimento sustentável encontra-se em fase inicial de abordagem, face ao número de artigos que contemplam o assunto no período analisado. Os estudos envolvendo a biotecnologia de bioflocos contemplados nessa metanálise pertencem especialmente a ordem técnica, seguida da sustentabilidade da tecnologia empregada e aspectos positivos com relação ao âmbito econômico. Não obstante, há um déficit na abordagem dos aspectos sociais envolvidos com a aplicação desta biotecnologia.

Production of Nile tilapia Oreochromis niloticus reared in a limited water exchange system: The effect of different light levels

This research aimed to investigate the impact of different levels of light on biological parameters, body composition and activity of liver and digestive enzymes of Nile tilapia (Oreochromis niloticus) in the biofloc system. The experiment was performed for 38 days in fiberglass tanks (with 150 l of water) with a density of one fish per liter. Nile tilapia fingerlings with an average weight of 1.73 ± 0.16 g and length of 4.13 ± 0.1 cm were selected. Three experimental treatments including 24 h of light (24hL), 12 h of light/12 h of darkness (12hL/12hD) and 24 h of darkness (24hD) with three replicates were considered. According to the results, the lowest amount of dissolved oxygen (5.67 mg L−1), pH (7.35), total ammonia nitrogen (2.01 mg L−1) and nitrite (0.24 mg L−1) were obtained in 24hD treatment. Body weight gain, specific growth rate (SGR), survival, feed conversion ratio (FCR) and condition factor were higher in the presence of light. The lowest amount of body protein (56.06%) and lipid (25.83%) was obtained in 24hD treatment (P < 0.05). The highest activity of liver enzymes (u mg−1 protein) including aspartate aminotransferase (AST: 2.98), alanine aminotransferase (ALT: 0.48) and alkaline phosphatase (ALP: 0.081) was observed in 24hD treatment. In conclusion, our results suggest that the presence of light improves carcass quality and activity of digestive and hepatic enzymes of Nile tilapia in the biofloc system.

Effect of different doses of saponins and salinity on giant tiger prawn Penaeus monodon and Nile tilapia Oreochromis niloticus

The Nile Tilapia Oreochromis niloticus is considering as a pest in shrimp farming ponds, as it is a shrimp competitor and predator of benthic organisms. This study aims to determine the effective and efficient saponins doses to eradicate tilapia without causing shrimp mortality. The study used two different saponins doses (200 kg/ha and 100 kg/ha) with seven different levels of salinity (5, 10, 15, 20, 25, 30, 35 ppt). The saponins doses used in this study had no effect on shrimp mortality, but had a significant effect on mortality of nile tilapia. The mortality of nile tilapia was 100% for all treatments. The death time of nile tilapia decreased significantly with increasing salinity. Longest nile tilapia death time was found at 10 ppt water salinity; this salinity is close to that of body fluids (14 ppt). The greater the difference between the ion content of body fluids and water ions in the test media, the faster the time of death. The effects of bleeding on the operculum, pectoral and caudal fins are more severe at high salinity. It is advisable not to increase the saponins doses, use the same saponins doses at any salinity, because predatory and competitive fish will die at any salinity.

EFFECTS OF PARTIAL SUBSTITUTION OF FISHMEAL BY SEA CLAM (SENILIA SENILIS)MEAT MEAL ON GROWTH PERFORMANCE, FEED EFFICIENCY, SURVIVAL, AND WHOLE-BODY COMPOSITION OF THE NILE TILAPIA (OREOCHROMIS NILOTICUS, L.1758)

The present study assessed the effects of incorporating sea clam (Senilia senilis)meat mealas a partial replacement for fishmeal on the growth performance, survival and whole-body composition of Nile Tilapia Oreochromis niloticus fry(0.2 g).Three iso-proteins (26%) and iso-caloric (11%) diets where fishmeal was substituted withclam meat meal at 0% diet A,10% diet B, and 15% diet C were prepared.The experiment was conductedfor 12 weeks. The stocking density was 15 fish per tank in an isolated system consisting of 9 plastic tanks of 80L each. Each treatment was administered in triplicates, and fish were fed three times per day (09 :00h, 13 :00h, and 17 :00h). The daily ration corresponded to 10% of the fishs live weight during the first month and was reduced to 8% and then 6% for the second and last month of the trial period.The results of this study showed that the incorporation of clam meat meal in the diet of Nile Tilapia fry has benefited growth in fish fed the tested diets. The best growth performance was obtained in the fish fed with diet B containing 10% clam meat meal: 10.57g for absolute mean weight gain 4.75% /d for SGR 0.82 for FCR 2.14 for PER, followed by diet A.Diet C has the lowest growth performance: 8.37g for weight gain,4.44%/d for SGR,0.99 for FCR, and 1.75 for PER. The best survival rate was obtained by diet C (93.33%), followed by diet B (80%), and the lowest by diet A (71.11%). The protein contents of the tested fish were moderately higher than that of the initial fish. No big difference was observed among the tested diets. The ash content is reduced sharply after two months feeding. The lipid content of the tested fish decreasedslightly in comparison to the initial fish. At the end of the study, fish fed with diet B showed the best growth performance among other diets. These results indicatethat clam meat meal can be included up to 15% in the tilapia diet without affecting the nutritional quality of the feed.

Identification and quantification of dicarboxylic fatty acids in head tissue of farmed Nile tilapia (Oreochromis niloticus)

Nile tilapia (Oreochromis niloticus) was grown in Bangladesh with four different feeding treatments as part of a project that aims to produce fish in a cost-effective way for low-income consumers in developing countries. Fillet and head tissue was analysed because both tissues were destined for human consumption. Gas chromatography with mass spectrometry (GC/MS) analyses of transesterified fatty acid methyl ester extracts indicated the presence of ~ 50 fatty acids. Major fatty acids in fillet and head tissue were palmitic acid and oleic acid. Both linoleic acid and polyunsaturated fatty acids with three or more double bonds were presented in quantities > 10% of total fatty acids in fillet, but lower in head tissue. Erucic acid levels were below the newly proposed tolerable daily intake in the European Union, based on the consumption of 200 g fillet per day. Moreover, further analysis produced evidence for the presence of the dicarboxylic fatty acid azelaic acid (nonanedioic acid, Di9:0) in head tissue. To verify this uncommon finding, countercurrent chromatography was used to isolate Di9:0 and other dicarboxylic acids from a technical standard followed by its quantification. Di9:0 contributed to 0.4–1.3% of the fatty acid profile in head tissue, but was not detected in fillet. Fish fed with increasing quantities of flaxseed indicated that linoleic acid was the likely precursor of Di9:0 in the head tissue samples.

Morphomolecular identification of two trichodinid coinfections ( Ciliophora : Trichodinidae ) and their immunological impacts on farmed Nile Tilapia

Trichodiniasis is one of the most serious ectoparasitic diseases disturbing tilapia aquaculture worldwide, causing deleterious effects and significant economic losses. This study aimed to characterize two Trichodina species concomitantly infecting farmed Nile tilapia Oreochromis niloticus based on integrated morphological, molecular, and immunological approaches. One hundred and eighty of 250 examined Nile tilapia were found to be infected with trichodinids belonging to the family Trichodinidae, with an overall prevalence rate of 72%. The morphological characterization of trichodinids fixed on Giemsa-stained smears revealed that fish were concomitantly infected with Trichodina heterodentata and T. centrostrigeata. Subsequently, the phylogenetic analysis of the 18S rRNA gene of the two investigated trichodinids confirmed the detected species’ identities. The gene expression levels of MHCIIβ and CD4 gens were increased during the trichodinid infection. Furthermore, potassium permanganate and hydrogen peroxide chemicals, which have well-known records for treating ectoparasites infections in farmed fish, were successfully verified to control trichodiniasis in a small-scale trial.

Evaluation of Dietary Soluble Extract Hydrolysates with or without Supplementation of Inosine Monophosphate Based on Growth, Hematology, Non-Specific Immune Responses and Disease Resistance in Juvenile Nile Tilapia Oreochromis niloticus.

Simple SummaryThis study was conducted to elucidate the effects of dietary soluble extract hydrolysates obtained from fishery by-products, such as shrimp soluble extract (SSE), tilapia soluble extract (TSE) and squid soluble extract (SQSE). Furthermore, we used a nucleotide, inosine monophosphate (IMP), as an additive in different concentrations along with shrimp soluble extract to understand their effects on growth, immunity and disease resistance in juvenile Nile tilapia. Our results demonstrated that dietary SSE could improve growth performance, non-specific immune responses and disease resistance against pathogenic bacteria Aeromonas hydrophila in juvenile Nile tilapia. Moreover, IMP did not add further benefits to the SSE diet. Further research is needed to better understand the effects of fishery by-products and IMP on fish diets.We performed an 8-week feeding trial to evaluate dietary soluble extract hydrolysates from fishery by-products, such as shrimp soluble extract (SSE) with or without inosine monophosphate (IMP), tilapia soluble extract (TSE) and squid soluble extract (SQSE), in juvenile Nile tilapia. A diet without feed additives was used as the control diet (CON); and five other experimental diets were formulated with 2% soluble extracts consisting of 100% SSE, 98% SSE + 2% IMP (SSEP2), 96% SSE + 4% IMP (SSEP4), 100% SQSE and 100% TSE. The diets were fed to 4.9 ± 0.07 g (mean ± SD) juvenile Nile tilapia in triplicate groups. The weight gain and specific growth rates of fish fed the SSE, SSEP2 and SSEP4 diets were significantly higher than those of fish fed the CON and SQSE diets. The superoxide dismutase activity levels of fish fed the SSE and SSEP4 diets were significantly higher than those of fish fed the CON, SSEP2, SQSE and TSE diets. Myeloperoxidase activity levels of fish fed the SSE and SSEP4 diets were significantly higher than those of fish fed the CON, SSEP2 and SQSE diets. Lysozyme activity levels of fish fed the SSEP4 and SQSE diets were significantly higher than those of fish fed the SSE and SSEP2 diets. Feed efficiency, protein efficiency ratio, survival rate, whole body proximate composition and hematological parameters were not significantly different among the groups. After ten days of challenge = against Aeromonas hydrophila, the cumulative survival rate of fish fed the SSE diet was significantly higher than those of fish fed the CON, SQSE and TSE diets. In conclusion, dietary shrimp soluble extract could improve the growth performance, non-specific immune responses and disease resistance in juvenile Nile tilapia, and inosine monophosphate did not add further benefits to this ingredient.

Influence of Fluctuating Water Temperature and Dietary Oxytetracycline on the Safety of Monosex Nile Tilapia Oreochromis niloticus Fries.

The influence of fluctuating water temperature and dietary oxytetracycline (OTC) at 0 (0X), 80 (1X), 240 (3X), 400 (5X) and 800mg (10X)/kg biomass/day for 30 consecutive days on the safety of monosex (all male) Nile tilapia Oreochromis niloticus fries in terms of feeding, growth, survival and histopathology of vital organs were assessed. A dose-dependent decline in feed intake and biomass was recorded. The OTC-dosed groups recorded higher mortalities than the control. The therapeutic OTC-dosing (1X) in conjunction with low temperature caused 75.56 ± 8.01% mortality and 25.75% reduced feed intake in 30days. The mortalities increased with increasing OTC-doses from 85.19 ± 3.39% (1X) to 95.56 ± 2.22% (10X) and fluctuating temperature (12.00-21.50°C) even after the withdrawal of OTC. Relatively mild to moderate histopathological lesions were observed in the kidney, liver and intestine of OTC-dosed fries. These results suggested that dietary OTC and low water temperature may cause adverse effects on monosex O. niloticus fries.

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

One of the many biomarkers for determining the effects of pollutants on fish is changes in organ histopathology. Leaves of Balanites aegyptiaca have been reported to have phytochemicals with fish anaesthetic property. This study sought to determine the effect of graded acute concentrations (200.00, 250.00, 300.00.350.00 and 400.00 mg/L) of B. aegyptiaca on histopathology of gills, kidney and liver of mixed sex of Oreochromis niloticus fingerlings. A total of 120 O. niloticus fingerlings (mean weight 23±0.03 g and mean total length 12.50±0.39 cm) were exposed to the plant extract. Paraffin wax method and haematoxylin-eosin staining techniques of tissue processing were adopted for the examination of the gills, kidney and liver. Dose-dependent histopathological changes were observed in the three organs (gills, kidney and liver) i.e. histopathological alterations increase with increase in concentration of the plant extract. Gills showed lamellae fusion, haemorrhage, desquamation, atrophy and secondary lamellae erosion while kidney and liver indicated atrophy, necrosis, haemorrhage, hyperplasia and hypertrophy. Structural alterations were evident in the gills, kidney and liver of O. niloticus fingerlings exposed to the concentrations of aqueous crude leaf extract of B. aegyptiaca therefore it should be used with caution during fish anaesthesia.&#x0D; Keywords: Histopathology; Gill; Kidney; Liver; Balanites aegyptiaca; Oreochromis niloticus.

An atypical KLRG1 in Nile tilapia involves in adaptive immunity as a potential marker for activated T lymphocytes

Killer cell lectin-like receptor G subfamily 1 (KLRG1) is a receptor generally expressed on effector CD8+ T cells or NK cells at terminal differentiation stage, and it will be highly induced for lymphocyte cytotoxicity upon pathogen infection or lymphocyte activation. However, little is known about the character or function of KLRG1 in lower vertebrates. In present study, we reappraised a molecule that previously defined as KLRG1 in the genomic sequence of Nile tilapia Oreochromis niloticus, and identified it as an atypical KLRG1-like molecule (defined as On-KLRG1-L), and illustrated its potential function serving as a marker representing effector T lymphocytes of fish species. On-KLRG1-L consists of two C-type lectin-like domains (CTLDs) without transmembrane region, and the tertiary structure of the CTLD is highly alike to that in mouse KLRG1. As a CTLD-containing protein, the recombinant On-KLRG1-L could bind PGN and several microbes in vitro. On-KLRG1-L was widely expressed in immune-associated tissues, with the highest expression level in the gill. Once Nile tilapia is infected by Aeromonas hydrophila, mRNA level of On-KLRG1-L in spleen lymphocytes were significantly up-regulated on 5 days after infection. Meanwhile, On-KLRG1-L protein was also induced on 5 or 8 days after A. hydrophila infection. Furthermore, we found both mRNA and protein levels of On-KLRG1-L were dramatically enhanced within several hours after spleen lymphocytes were activated by T cell-specific mitogen PHA in vitro. More importantly, the ratio of On-KLRG1-L+ T cells was also augmented after PHA stimulation. The observations suggested that the KLRG1-like molecule from Nile tilapia participated in lymphocyte activation and anti-bacterial adaptive immune response, and could serve as an activation marker of T lymphocytes. Our study thus provided new evidences to understand lymphocyte-mediated adaptive immunity of teleost.

TEKNIK BUDIDAYA IKAN NILA DENGAN METODA AQUAPONIK RAMAH LINGKUNGAN PADA KELOMPOK WANITA TANI (KWT) DESA PADANG BIRIK-BIRIK KOTA PARIAMAN – SUMATERA BARAT

Desa Padang Birik-Birik was located in the North Pariaman District of Pariaman City and the village near to the beach. The daily activities of women in this area are housewives and farming. During the Covid-19 pandemic the economic conditions of the community became increasingly difficult so that the additional alternative funds were needed to meet family needs. Nile Tilapia (Oreochromis niloticus) cultivation techniques with an aquaponic system can be used as a source of additional income in addition to meet the nutritional needs of the family. Nile Tilapia cultivation techniques with an aquaponic system can increase the income of housewives during the Covid-19 pandemic. Aquaponic method is a land and water saving technology that can be combined with various vegetable crops. Meanwhile, vegetable crops from the aquaponic system can also be consumed to meet the nutritional needs of the family. This community service activity is carried out by counseling and direct practice. Presentation of material on Nile Tilapia cultivation techniques using the aquaponic system includes how to assemble tools, direct practice how to plant seeds, and how to maintain them. The result of the activity was that the enthusiastic community received the material presented and seriously followed the activity until it was finished. The community is committed to trying to make this aquaponic cultivation system themselves in their respective homes.

Pond-adjacent grass height and pond proximity to water influence predation risk of pond fish by amphibians in small fish ponds of Kakamega County, western Kenya

The study investigated predation risk to pond-reared Nile Tilapia Oreochromis niloticus and African Catfish Clarias gariepinus by amphibians, whether this is driven by height of pond-side grass or pond proximity to surface-water source and how this varies with fish stocking options. Based on small-scale freshwater aquaculture farms in western Kenya, field surveys were conducted during three sampling seasons spread across 6 months. These involved the following: (1) a sociological survey of 29 fish farming households; (2) sampling of amphibians for density, species richness and encounter rates and (3) measuring grass height, pond dimensions and water-source proximity across 24 ponds. Overall, 131 individual frogs from three families were recorded in 78 encounters. Amphibian density increased with pond-side grass height, presumably increasing predation risk, but decreased with water-source proximity. Amphibian encounter rate also decreased with water-source proximity, but was unaffected by grass height, while species richness responded positively to pond-side grass height, but not to water-source proximity. Amphibian encounter likelihood was higher in tilapia-only than in catfish-only or tilapia and catfish ponds irrespective of habitat variables. We demonstrate here that management practices for mitigating fish loss to predatory amphibians should include trimming pond-side vegetation, siting ponds close-to-moderate distances from water-sources and including catfish in pond polycultures.

Effect of Rosemary Extract and Vitamin E on Lipid Peroxidation and the Quality During Chilling and Frozen Storage of Fried Nile Tilapia Fillets (Oreochromis niloticus)

Antioxidants are added to fresh and processed meat to prevent lipid oxidation, retard development of off-flavors, and improve color stability. Synthetic antioxidants have been confirmed for their toxicological and carcinogenic effects. Thus, the food industry now chooses natural products over synthetic ones. This study was carried out to investigate the effect of Rosemary extract (R.E.) and vitamin E on the quality of fried fillets of Nile tilapia (Oreochromis niloticus) during chilling and frozen storage. Fillets of Nile tilapia were treated with (R.E.) 0.1%, 0.2%, 0.3% and Vitamin E 0.1% then stored for 5,10 and 15 days at 4±1°C and for three months at -18±2°C. Then chemical tests including Peroxide value (PV), Thio-barbituric acid (TBA), Tri-methylamine-nitrogen (TMA-N) and Total volatile base-nitrogen (TVB-N) were done to evaluate the preservative effect of (R.E.) and vitamin E during storage. The TBA and PV increased in all treatments due to lipid peroxidation. Results showed that TMA-N,TVB-N, value of (R.E.) and vitamin E treated samples were significantly lower than those of the control samples (P&lt;0.05). Results of our investigation revealed that R.E. retarded oxidative changes in chilling and frozen fried fillets of Nile tilapia whereas R.E. 0.1%, 0.2% and vitamin E 0.1% were not as effective as R.E. 0.3% on oxidative stability. Best oxidation inhabitation results on chilling and frozen fried fillets of Nile tilapia was obtained when employing of R.E. The obtained results also showed that there was a significant (p&lt;0.05) enhancement in sensory quality attributes of fried fillets of Nile tilapia; samples treated with R.E. and vitamin E. Conclusion, The tested R.E. had a high effectiveness as antioxidative and antimicrobial should be utilized for extending the shelf-life through retarded the spoilage and enhancing quality attributes of fried fillets of Nile tilapia during chilling and frozen storage.

Expression of Repressor Element 1 Silencing Transcription Factor (REST) in Serotonin Neurons in the Adult Male Nile Tilapia (Oreochromis niloticus).

Repressor element-1 silencing transcription factor (REST) is highly expressed in the dorsal raphe where serotonin (5-hydroxytryptamine, 5-HT) neurons are located. REST works as a transcription factor for the 5-HT receptor and tryptophan hydroxylase two-gene expression. We hypothesized that REST is co-expressed in 5-HT neurons, which, if demonstrated, would be useful to understand the mechanism of 5-HT dysfunction-related disorders such as negative emotions and depression. Therefore, the present study was designed to examine the expression of the REST gene in the brain (forebrain, midbrain, and hindbrain) of adult male Nile tilapia (Oreochromis niloticus) using rt-PCR. Besides, using immunocytochemistry, co-localization of the REST gene was examined in 5-HT neurons and with neuronal-/glial-cell markers. We found a high expression of the REST gene in the midbrain region of the dorsal raphe, an area of 5-HT neurons. Double-label immunocytochemistry showed neuron-specific expression of REST co-localized in 5-HT neurons in the dorsal and ventral parts of the periventricular pretectal nucleus, paraventricular organ, and dorsal and medial raphe nucleus. Since midbrain 5-HT neurons express REST, we speculate that REST may control 5-HT neuronal activity related to negative emotions, including depression.

Description of Freshwater Fish Traditional Smoking in the Western Region, Cameroon

Western Cameroon is one of the regions most in needs of innovative and healthy solutions for freshwater fish conservation. This study aimed at evaluating the socio-economical characteristics of fish smokers and technical factors on the species smoked in the Noun Division. A total of 91 fish smokers were chosen. The socio-economic data were on age, gender, religion, number of dependents, marital status, ethnic group, education level, economic activities, smoking goals and workforce. The results of this study showed that fish smoking is practiced mainly by women (70%) which is common in Sub Sahara Africa small scale fish sector. The smokers are aged from 20 to 50 years (80%), married (92.2%) and taking care of a family of 1 to 10 persons (80%). These smokers are Muslim (74%), belonging to the Bamoun ethnic group (81%). They were also involved in other activities: agriculture (29%) and trade (1%). About 67% of the sampled smokers’ population had an experience of more than 10 years in the domain. The Purpose of smoking was largely sales (97%) and subsistence (3%). Nile tilapia (Oreochromis niloticus) was the most smoked species (36%), followed by African catfish (Clarias gariepinus) with a proportion of 32%. The average quantity of fresh fish smoked was 110 kg/day/smoker, with Oreochromis niloticus being more produced (60±4.74 kg/day/smoker). With regard to the smoking techniques used, hygiene measures were poorly respected. The major constraints revealed by the survey were that freshwater’s traditional fish smoking activities in Noun Division are influenced by gender, economic and cultural background. There is a lack of technical support material and financial means. Any implications for future investigations on health and food safety will be suitable for fresh fish smokers and the entire consumers.

Water quality and health status of the monosex Nile Tilapia, Oreochromis niloticus cultured in aquaponics system (ASTAF-PRO)

The present study is a part of a cooperative project to enable the efficient transfer of innovative ecotechnology ASTAF-PRO aquaponic from Germany to Egypt for sustainable aquaculture and food production. The present part was carried out to evaluate the impact of ASTAF-PRO aquaponic system on water quality parameters and the health status of the monosex Nile tilapia Oreochromis niloticus. Water quality analysis revealed an improvement of most parameters in an aquaponic system with a significant reduction in toxic ammonia. In aquaponic, the nitrite level in ASTAF-PRO was lower than the permissible limit, probably because of the double-sided action of nitrobacteria present in the biological filters and the grow beds of the plant in the system. No significant difference was observed in the values of nearly all the hematological parameters in the blood of fishes reared in the aquaponic system and those reared in POND systems, being always within the normal ranges for the healthy Nile tilapia. Most of the measured biochemical variables exhibited an improvement in the blood of fish reared in the ASTF-PRO system compared to that of the POND. This suggests that fish health improved when reared in aquaponic with better water quality parameters. Immunoglobulin (IgM) levels and lysozyme activity were the same in the blood of fish reared in both systems, confirming that the monosex Nile tilapia was still fit with a good immunological status under aquaponic condition. In conclusion, the health status of the monosex Nile tilapia reared in ASTAF-PRO aquaponic system was better than those reared in POND in terms of hematology, biochemistry and immunological status. Obviously, the difference in the health status of fish in different systems can be linked to water quality since the same feed was used.

Essential role of 4E-BP1 for lymphocyte activation and proliferation in the adaptive immune response of Nile tilapia

Eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP1) is a translation repressor downstream of mTORC1 pathway, and plays a pivotal role in the adaptive immune response. However, whether 4E-BP1 participates in the regulation of adaptive immunity of early vertebrates is still unclear. In present study, using Nile tilapia Oreochromis niloticus as a model, we investigated the regulatory roles of 4E-BP1 (On-4E-BP1) on lymphocyte-mediated adaptive immune response of fish species. On-4E-BP1 is highly conserved compared with the homologues from other vertebrates, and it is widely distributed in the immune-related tissues of Nile tilapia with the highest expression level in the gill. Once the animals were infected by Aeromonas hydrophila, transcription level of On-4E-BP1 in spleen lymphocytes was significantly induced on day 5 after infection. Meanwhile, phosphorylation of On-4E-BP1 in lymphocytes was also enhanced during the primary adaptive immune response, suggesting that 4E-BP1 is involved in the adaptive immunity of Nile tilapia. Furthermore, when lymphocytes were activated by agonist PMA or T cell specific mitogen PHA in vitro, phosphorylation of On-4E-BP1 was obviously up-regulated. More importantly, once mTORC1/4E-BP1 activity was blocked by specific inhibitor, the inducible expression of T cell activation markers IFN-γ and CD122 was severely impaired during PHA-induced T cell activation, suggesting this signaling regulates T lymphocyte activation of Nile tilapia. In addition, blockade of mTORC1/4E-BP1 axis also resulted in a crippled proliferation of lymphocyte during the primary response of anti-bacterial adaptive immunity. Collectively, we found that mTORC1/4E-BP1 signaling participates in the adaptive immune response by regulating lymphocyte activation and proliferation in Nile tilapia. This study enriches our current knowledge on teleost adaptive immunity, and provides novel perspective to understand the evolution of adaptive immune system.

Akt1/mTORC1 signaling modulates adaptive immune response of Nile tilapia by promoting lymphocyte activation and proliferation

Serving as a significant signaling molecule, RAC-alpha serine/threonine-protein kinase (Akt1) plays indispensable roles in cell cycle, growth, survival, metabolism, as well as immune response. However, how Akt1 regulates adaptive immune response in early vertebrate, especially the teleost, is largely unknown. Here, using a Nile tilapia Oreochromis niloticus model, we investigated the regulatory role of Akt1 in adaptive immunity of teleost. Both sequence and structure of the O. niloticus Akt1 (OnAkt1), were evolutionarily conserved comparing with the counterparts from other vertebrates. mRNA of OnAkt1 was widely expressed in lymphoid organs/tissues of Nile tilapia, with relative higher level in PBL. After Nile tilapia was infected by Aeromonas hydrophila, both transcription and phosphorylation levels of OnAkt1 were obviously elevated in spleen lymphocytes at the adaptive immune stage, suggesting Akt1 participated in primary adaptive immune response of Nile tilapia. Furthermore, OnAkt1 transcript or phosphorylation was dramatically augmented after spleen lymphocytes were activated by T cell specific mitogen PHA or lymphocyte agonist PMA. More critically, inhibition of Akt1 by specific inhibitor crippled the activation of downstream mTORC1 signaling, and impaired the up-regulation of T cell activation markers CD44, IFN-γ and CD122 in spleen lymphocytes upon PHA-induced T cell activation. Meanwhile, blockade of Akt1-activated mTORC1 signaling also decreased the frequency of BrdU+ lymphocytes during A. hydrophila infection, indicating the critical role of Akt1 in regulating lymphocyte proliferation of Nile tilapia. Together, our results demonstrated that Akt1 modulated adaptive immune response of Nile tilapia by promoting lymphocyte activation and proliferation via mTORC1 signaling. Our study enriched the regulatory mechanism of lymphocyte-mediated adaptive immunity in teleost, and thus provided novel insights into the evolution of adaptive immune system.

The impact of turbidity on foraging and risk taking in the invasive Nile tilapia (Oreochromis niloticus) and a threatened native cichlid (Oreochromis amphimelas)

Anthropogenic activity can increase water turbidity, changing fish behaviour by reducing visibility. The spread of invasive species is also facilitated by human activity, further increasing the pressure on native species. In two experiments, we measured the foraging efficiency, risk perception and inter-individual consistency of risk-taking (personality variation in boldness) of an invasive species, the Nile tilapia (Oreochromis niloticus), and a threatened tilapia, the Manyara tilapia (Oreochromis amphimelas), in clear and turbid water. In experiment one, O. niloticus was faster to initiate feeding, encountered more food items and consumed more than O. amphimelas. The latency to start foraging by O. niloticus decreased in turbid water. Turbidity did not affect the latency to start foraging in O. amphimelas but the number of food items they encountered was highest at the intermediate turbidity. There was however no significant effect of turbidity in either species on the total food consumed. In contrast to this foraging context, in experiment two with a refuge and no food available, risk taking behaviour was similar in both species and they both responded with similarly reduced risk taking in turbid water. Evidence of personality variation was weak, being observed only in O. amphimelas when first leaving the shelter in turbid water. Overall, species differences were greater in the foraging context but turbidity was more important in the risk-taking context. O. amphimelas is more sensitive to turbidity during foraging, and O. niloticus is likely to have a competitive advantage in foraging situations, especially in degraded turbid habitats.Significance statementUnder human-induced environmental change, native species are often exposed to multiple stressors. Here, we tested the responses of two cichlid fish to increasing turbidity, the Nile tilapia (Oreochromis niloticus), which is invasive throughout the tropics, and the Manyara tilapia (Oreochromis amphimelas), a threatened species, indigenous to Tanzania. We found that turbidity was beneficial to the foraging of O. niloticus, which in both clear and turbid water consumed and encountered more food than O. amphimelas. In contrast, without food present, both species displayed similar responses of increased risk perception in turbid water with little evidence of personality variation between individuals in either species. Our results suggest that invasive species tolerant of degraded habitats may outcompete less well-adapted native species for food.

Transcriptome analysis of liver elucidates key immune-related pathways in Nile tilapia Oreochromis niloticus following infection with tilapia lake virus

Nile tilapia (Oreochromis niloticus) is one of the most important aquaculture species farmed worldwide. However, the recent emergence of tilapia lake virus (TiLV) disease, also known as syncytial hepatitis of tilapia, has threatened the global tilapia industry. To gain more insight regarding the host response against the disease, the transcriptional profiles of liver in experimentally-infected and control tilapia were compared. Analysis of RNA-Seq data identified 4640 differentially expressed genes (DEGs), which were involved among others in antigen processing and presentation, MAPK, apoptosis, necroptosis, chemokine signaling, interferon, NF-kB, acute phase response and JAK-STAT pathways. Enhanced expression of most of the DEGs in the above pathways suggests an attempt by tilapia to resist TiLV infection. However, upregulation of some of the key genes such as BCL2L1 in apoptosis pathway; NFKBIA in NF-kB pathway; TRFC in acute phase response; and SOCS, EPOR, PI3K and AKT in JAK-STAT pathway and downregulation of the genes, namely MAP3K7 in MAPK pathway; IFIT1 in interferon; and TRIM25 in NF-kB pathway suggested that TiLV was able to subvert the host immune response to successfully establish the infection. The study offers novel insights into the cellular functions that are affected following TiLV infection and will serve as a valuable genomic resource towards our understanding of susceptibility of tilapia to TiLV infection.