ARTICLE | doi:10.20944/preprints202201.0015.v1
Subject: Biology, Agricultural Sciences & Agronomy Keywords: tilapia broodstock; inactivated vaccines; maternal passive immunity; antibody
Online: 4 January 2022 (15:41:19 CET)
Tilapia lake virus (TiLV), a major pathogen of farmed tilapia, is known to be vertically transmitted. Here, we hypothesize that Nile tilapia (Oreochromis niloticus) broodstock immunized with a TiLV inactivated vaccine can mount a protective antibody response and passively transfer maternal antibodies to their fertilized eggs and larvae. To test this hypothesis, three groups of tilapia broodstock, each containing 4 males and 8 females, were immunized with either a heat-killed TiLV vaccine (HKV), a formalin-killed TiLV vaccine (FKV) (both administered at 3.6 ×106 TCID50 per fish), or with L15 medium. Booster vaccination with the same vaccines was given 3-weeks later, and mating took place 1 week thereafter. Broodstock blood sera, fertilized eggs and larvae were collected from 6-14 weeks post-primary vaccination for measurement of TiLV-specific antibody (anti-TiLV IgM) levels. In parallel, passive immunization using sera from the immunized female broodstock was administered to naïve tilapia juveniles to assess if antibodies induced in immunized broodstock were protective. The results showed that anti-TiLV IgM was produced in the majority of both male and female broodstock vaccinated with either the HKV or FKV and that and that these antibodies could be detected in the fertilized eggs and larvae from vaccinated broodstock. Higher levels of maternal antibody were observed in fertilized eggs from broodstock vaccinated with HKV than those vaccinated with FKV. Low levels of TiLV-IgM were detected in some of the 1-3-day old larvae but were undetectable in 7-14-day old larvae from the vaccinated broodstock, indicating a short persistence of TiLV-IgM in larvae. Moreover, passive immunization proved that antibodies elicited by TiLV vaccination were able to confer 85% to 90% protection against TiLV challenge in naïve juvenile tilapia. In conclusion, immunization of tilapia broodstock with TiLV vaccines could be a potential strategy for the prevention of TiLV in tilapia fertilized eggs and larvae, with HKV appearing to be more promising than FKV for maternal vaccination.
ARTICLE | doi:10.20944/preprints202107.0626.v1
Subject: Life Sciences, Biochemistry Keywords: tilapia; negative-sense RNA virus; Tilapia lake virus; DNA vaccine
Online: 28 July 2021 (11:11:37 CEST)
Tilapia lake virus (TiLV) is the main tilapia-infecting virus worldwide, causing serious economic losses. However, there is no vaccine for this viral disease. Here, TiLV ORF10 (TiLV-ORF10) encoding a protein with abundant epitopes was constructed into the eukaryotic expression vector pcDNA3.1, and used to evaluate the immune protective effects in Nile tilapia (Oreochromis niloticus). RT-PCR and western blot analyses conﬁrmed vaccine plasmid expression in tilapia muscle tissues. Moreover, the transcription levels of immunoglobulin M, toll-like receptor 2, myeloid differentiation factor 88, interleukin 8, tumor necrosis factor alpha, gamma-IFN, and nuclear factor κB immune-related genes were statistically signiﬁcantly upregulated in the spleen, liver, and kidney of vaccinated tilapias (P < 0.05). TiLV challenge experiments showed that relative percent survival (RPS) was signiﬁcantly enhanced in ﬁsh by this DNA vaccine. Moreover, RPS was enhanced further when using a higher amount of the DNA vaccine (85.72% RPS at a DNA dose of 45 μg pcDNA3.1–ORF10). Vaccination with pcDNA3.1–ORF10 signiﬁcantly reduced virus replication, as evidenced by the low amount of virus in the spleen, liver, and kidney of vaccinated tilapias after TiLV challenge. Thus, pcDNA3.1–ORF10 could induce protective immunity in tilapia and may be a potential vaccine candidate for controlling diseases caused by TiLV.
ARTICLE | doi:10.20944/preprints202101.0485.v1
Subject: Medicine & Pharmacology, Allergology Keywords: Nile tilapia; CuONPs; Histopathology; Gene transcription; Toxicity
Online: 25 January 2021 (11:31:48 CET)
In the present study, fish were exposed to sub-lethal doses of CuONPs (68.92 ± 3.49 nm) (10, 20, and 50 mg/L) for a long exposure period (25 days). Compared to the control group (0.0 mg/L CuONPs), a significant dose-dependent elevation in blood urea and creatinine values, serum alanine transaminase, aspartate transaminase, and alkaline phosphatase enzyme activities were evident in CuONPs-exposed groups (P < 0.05). Fish exposure to 50 mg/L CuONPs significantly upregulated the transcription of pro-inflammatory cytokines (tumor necrosis factor-alpha, interleukin-1beta, interleukin 12, and interleukin 8), heat shock protein 70, apoptosis-related gene (caspase 3), and oxidative stress-related (superoxide dismutase, catalase, and glutathione peroxidase) genes in liver and gills of the exposed fish in comparison with those in the control group (P < 0.05). Moreover, varying histopathological injuries were noticed in the hepatopancreatic tissues, posterior kidneys, and gills of fish groups correlated to the examined exposure dose of CuONPs. In summary, our results provide new insights and helpful information for better understanding the mechanisms of CuONPs toxicity in Nile tilapia at hematological, molecular levels, and tissue levels.
ARTICLE | doi:10.20944/preprints201902.0106.v1
Online: 12 February 2019 (17:14:54 CET)
The black-chinned tilapia Sarotherodon melanotheron is the most abundant fish species in the Nakwa (a closed lagoon) and Brenu (an open lagoon) in the Central region of Ghana. Aspects of the life history characteristics and the ecology of the fish populations in both lagoons were studied to assess the bio-ecological status of this important resource. The estimated von Bertalanffy growth parameters were L∞ = 12.04 cm; K =2.76 year-1 for the Nakwa Lagoon samples and L∞ = 13.44 cm; K = 3.27 years-1 for Brenu Lagoon samples. Daily otolith incremental rate ranged from 0.01-0.03mm per day and 0.01-0.02mm per day for Nakwa and Brenu lagoons respectively. Stomach content analysis of the fish samples revealed that the species are planktivorous and the range of food varied between the lagoons. Green algae was the most prevalent food item in the stomachs of the fish samples from Nakwa with frequency of 69% while diatoms (80.5%) were most prevalent phytoplanktonic food item in for the fish in Brenu lagoon. The results of this study of Sarotherodon melanotheron from the two lagoons and can be used to improve on management policies, maximize yield and to sustain the fishery resources.
ARTICLE | doi:10.20944/preprints201911.0282.v1
Subject: Biology, Animal Sciences & Zoology Keywords: Nile tilapia; pseudomonas; antibiotic resistance; biofilm formation; virulence genes
Online: 24 November 2019 (14:11:40 CET)
Pseudomonas aeruginosa (P. aeruginosa) produces a suite of virulence factors that are coordinated by Quorum Sensing (QS) contributing to its disease-causing ability in aquaculture. The present study is first of its kind to obtain information regarding the presence and distribution of five QS genes, three virulence genes viz: lasI, lasR, rhlI, rhlR, rhlAB, toxA, aprA and plcH and seven of the Extended-spectrum βlactamases (blaVEB, blaPER, blaTEM,, blaSHV, blaCTX-M1, blaCTX-M2 and blaCTX-M3) of Pseudomonas species isolated from fish meat by direct PCR. Bacterial identification was based mainly on conventional biochemical techniques using the Vitek 2, automated system. Phenotypic sensitivity of antibiotics was established by the agar disc diffusion technique through 16 various antimicrobial drugs. Quantification of their in vitro production of numerous virulence genes outside the cell that are QS dependent namely, pyocyanin, elastase, alkaline protease, biofilm and cytotoxicity of Vero cell was as well executed. Fifteen genes demonstrated an enormous variety in their association. The total number of Pseudomonas species isolates were 30/100 to be identified by the API 20NE system as P. aeruginosa 12/30 (40%), P. fluorescens 8/30 (27%), P. putida 6/30 (20%) and P. alkylphenolia 4/30 (13%). The outcomes of this study have great significance for the strategic designation of QS quenching.
ARTICLE | doi:10.20944/preprints202105.0454.v1
Subject: Life Sciences, Biochemistry Keywords: feed efficiency; Nile tilapia; paring coconut and candlenut; plant oils; selenium
Online: 19 May 2021 (17:04:02 CEST)
This study aims to get growth and feed efficiency of Nile tilapia (Oreochromis niloticus) with plant oils supplement from paring coconut (P.C.) and candlenut (C.N.) enrichment of Se in rations formula. The oil of P.C. was dominated by saturated fatty acid (SFA) lauric (42.67%), while the extract of C.N. was unsaturated fatty acids (UFA), linoleic (34.4%), and oleic (48.99%). The extract of P.C. and C.N. or mix oils added 4% in basal ration formula (28% crude protein (C.P.) with energy-protein ratio 8 kcal/kg). Completely Randomized Design (6 × 3) consists R1: basal ration; R2: basal formula with blend of paring coconut and candlenut oils (2% PC + 2% CN); R3: blend oils (R2) with trace additive Se; R4: 4% PC + Se; R5: 4% CN + Se; R6: control ration (32% CP). The result of production parameters showed that blend oils supplement enrichment Se 0.15 ppm in feed formula with ratio SFA: UFA = 1: 1 was the best growth rate equal with high protein feed. Feed efficiency ranged from 50.14-57.93% and protein efficiency ratio 1.72-2.06 both for CN oil (SFA: UFA = 1 : 2), paring coconut (SFA : UFA = 2 : 1) or blend oils (SFA : UFA = 1 : 1). Incorporation of blend oils with Se can be used for Nile tilapia fingerlings (≥ 10 g). Paring coconut oil was trend increasing on feed efficiency for tilapia bigger stadium (≥ 30 g).
ARTICLE | doi:10.20944/preprints202101.0155.v2
Subject: Life Sciences, Biochemistry Keywords: Aquaponics; Tilapia; Clarias; Bacteroidetes, Proteobacteria, Actinobacteria, extracellular enzymes, Pseudomonas flourescens; Pseudomonas veronii, plant growth promotion, In vitro antagonistic
Online: 8 February 2021 (15:46:08 CET)
Background: Aquaponics are food production systems advocated for food security and health. Their sustainability from a nutritional and plant health perspective is, however, a significant challenge. Recirculated aquaculture systems (RAS) form a major part of aquaponic systems, but knowledge about their potential to benefit plant growth and plant health is limited. The current study tested if the diversity and function of microbial communities in two commercial RAS were specific to the fish species used (Tilapia or Clarias) and sampling site (fish tanks and wastewaters), and whether they confer benefits to plants and have invitro antagonistic potential towards plant pathogens. Results: Microbial diversity and composition was found to be dependent on fish species and sample site. The Tilapia RAS hosted higher bacterial diversity than the Clarias RAS; but the latter hosted higher fungal diversity. Both Tilapia and Clarias RAS hosted bacterial and fungal communities that promoted plant growth, inhibited plant pathogens and encouraged biodegradation. The production of extracellular enzymes, related to nutrient availability and pathogen control, by bacterial strains isolated from the Tilapia and Clarias systems, makes them a promising tool in aquaponics and in their system design. Conclusions: This study explored the microbial potential of the commercial RAS with either Tilapia or Clarias as a tool to benefit the aquaponic system with respect to plant growth promotion and control of plant diseases.
ARTICLE | doi:10.20944/preprints202009.0475.v1
Subject: Biology, Other Keywords: Nile tilapia; Oreochromis niloticus; liver; duckweed; Lemna minor; Cu; Zn; Glutathione Peroxidase; GPx; Glutathione-S-Transferase; GST; Superoxide dismutase; SOD; Catalase; CAT; remediation assessment
Online: 20 September 2020 (14:41:41 CEST)
A two-fold integrated research study was conducted; firstly, to understand effects of copper (Cu) and zinc (Zn) on the growth and oxidative stress in Nile tilapia, Oreochromis niloticus; secondly, to study the beneficial effects of the duckweed Lemna minor L. as a heavy metal remover from wastewater. Experiments were conducted in mesocosms with and without duckweed. Tilapia fingerlings were exposed to Cu (0.004 and 0.02 mg/L) and Zn (0.5 and 1.5 mg/L) and fish fed for four weeks. We evaluated the fish growth performance, the hepatic DNA structure using comet assay, the expression of antioxidative genes (superoxide dismutase, SOD; catalase, CAT; glutathione peroxidase, GPx and glutathione-S-transferase, GST) and GPx and GST enzymatic activity. The results showed that Zn exhibited more pronounced toxic effects than Cu. Low dose of Cu did not influence the growth whereas higher doses of Cu and Zn significantly reduced the growth rate of tilapia compared to control, but addition of duckweed prevented weight loss. Further, in the presence of a high dose of Cu and Zn, DNA damage decreased, antioxidant gene expressions and enzymatic activities increased. In conclusion, results suggest that duckweed and Nile tilapia can be suitable candidates in metal remediation wastewater assessment programs.