Tilapia is one of the most common fish species that is intensively produced all over the world. However, significant measures at improving aquaculture health must be taken since disease outbreaks are often encountered in the rapidly developing aquaculture industry. Therefore, the objective of the study was designed to evaluate the metabolite changes in tilapia' sera through 1H NMR metabolomics in identifying the potential biomarkers responsible for immunomodulatory effect by the indigenous species of Malaysian microalgae Isochrysis galbana (IG). The results showed that IG-incorporated diet mainly at 5.0% has improved the immune response of innate immunity as observed in serum bactericidal activity (SBA) and serum lysozyme activity (SLA). The orthogonal partial least squares (OPLS) analysis indicated 5 important metabolites significantly upregulated namely as ethanol, lipoprotein, lipid, α-glucose and unsaturated fatty acid (UFA) in the 5.0% IG-incorporated diet compared to control. In conclusion, this study had successfully determined IG in improving aquaculture health through its potential use as an immune modulator. This work also demonstrated the effective use of metabolomics approach in the development of alternative nutritious diet from microalgae species to boost fish health in fulfilling the aquaculture's long-term goals.
Group B Streptococcus (GBS) is a major cause of several infectious diseases in humans and fish. This study was conducted to compare human and fish-derived GBS in terms of their antimicrobial susceptibility, serotype, virulence and pili genes and sequence type (ST), and to determine whether there is a potential linkage of zoonotic transmission in Malaysia. GBS isolated from humans and fish had similar phenotypic characteristics and differed in virulence gene profile, antimicrobial susceptibility, serotype and sequence type. Fish GBS isolates had lower genetic diversity and higher antibiotic susceptibility than human isolates. We report a rare detection of the potentially fish-adapted ST283 in human GBS isolates. Both human and fish ST283 shared several phenotypic and genotypic features, including virulence and pilus genes and antimicrobial susceptibility, illustrating the value of monitoring GBS within the One Health scope. In this study, two human GBS ST283 isolates belonging to the variant common in fish hosts were identified, raising awareness of the zoonotic potential between the different species in Malaysia.
Serratia marcescens is an opportunistic bacterial pathogen with broad range of host ranging from vertebrates, invertebrates and plants. S. marcescens strain W2.3 was isolated from a diseased tilapia fish and it was suspected to be the causal agent for the fish disease as virulence genes were found within its genome. In this study, for the first time, the genome sequences of S. marcescens strain W2.3 were sequenced using the Illumina MiSeq platform.
Extraction of gelatin using traditional acid-base pretreatment method has several limitations
such as time consuming and causes serious water pollution. Chemical treatment often being used
as an alternative process to overcome the weaknesses of the conventional method. However,
excessive chemical elements would damage the structure of the gelatin due to its high sensitivity
to the acid content. High Pressure Processing (HPP) is a novel and environmental friendly
method that has been suggested to assist gelatin extraction. Pressurization during pretreatment
could reduce the extraction time and amount of acid used. It also has a potential in enhancing the
properties of the gelatin extract and increasing the gelatin yield. In this research, One-Factor-
at-Time (OFAT) and optimization study were done to determine the optimum parameters for
extraction of gelatin assisted by HPP from red tilapia skin. Four parameters; applied pressure,
pressure holding time, ratio of acid to skin and extraction time have been selected for the OFAT
design and concentration of the gelatin extract and percentage of yield gelatin were evaluated.
From OFAT, optimum technical parameters for response surface optimization design were 250
MPa pressure, 7.5 ml of acid to 1 g of skin and 12 hours extraction time. Pressure holding
time was fixed for 10 min. FCCCD has been used for optimization study. Results from the
data shows that the optimum conditions for gelatin extraction from red tilapia skin were 250
MPa for pressure, 10 min of pressure holding time, 7.5 ml of acid for 1 g of skin and 12 hours
of extraction time while the maximum concentration and yield were 19.51 mg/ml and 32.04%
(320.4 mg/g), respectively. These findings proved that HPP could increase the concentration
and the yield of the gelatin while reducing the chemical waste and shortening the extraction
process.
Fish protein hydrolysate was recovered from tilapia by-product (TB) through enzymatic hydrolysis using alcalase enzyme. Hydrolysis reaction of TB was monitored according to the degree of hydrolysis (DH) by employing O-phtaldialdehyde (OPA) method. Optimization process for obtaining high yield of TB protein hydrolysate was performed using response surface methodology (RSM) by optimizing a combination of four independent variables namely, pH (6.5-8.5), temperature (55-70oC), substrate concentration (10-17.5% w/v), and enzyme concentration (1.5-3.5% w/w) with (DH) as a response. The optimum enzymatic hydrolysis conditions were obtained at pH 7.5, temperature of 60oC, substrate concentration of 15% (w/v) and 2.5% (w/w) of enzyme concentration and yielded about 20.20% of DH after hydrolyzing for 120 min. RSM generated model predicted that 20.42% of DH could be achieved at these conditions and this model was valid based on the DH value obtained from the experimental study (20.31%) which was quite similar with the predicted value. High yield of DH obtained from the optimization process could produce fish protein hydrolysate with good nutritional and functional properties.
Injury to neuronal tissues in the central nervous system (CNS) of mammals results in neural degeneration and sometime leads to loss of function, whereas fish retain a remarkable potential for neuro-regeneration throughout life. Thus, understanding the mechanism of neuro-regeneration in fish CNS would be useful to improve the poor neuro-regenerative capability in mammals. In the present study, we characterized a neuro-regenerative process in the brain of a cichlid, tilapia, Oreochromis niloticus. Morphological observations showed that the damaged brain region (habenula) successfully regrew and reinnervated axonal projections by 60 days post-damage. A fluorescent carbocyanine tracer, DiI tracing revealed a recovery of the major neuronal projection from the regenerated habenula to the interpenduncular nucleus by 60 days post-damage. TUNEL assay showed a significant increase of apoptotic cells (~234%, P<0.01) at one day post-damage, while the number of bromodeoxyuridine (BrdU)-positive proliferative cells were significantly increased (~92%, P<0.05) at 7 days post-damage compared with sham-control fish. To demonstrate a potential role of apoptotic activity in the neuro-regeneration, effects of degenerative neural tissue on cell proliferation were examined in vivo. Implantation of detached neural but not non-neural tissues into the cranial cavity significantly (P<0.01) increased the number of BrdU-positive cells nearby the implantation regions at 3 days after the implantation. Furthermore, local injection of the protein extract and cerebrospinal fluid collected from injured fish brain significantly induced cell proliferation in the brain. These results suggest that factor(s) derived from apoptotic neural cells may play a critical role in the neuro-regeneration in teleost brain.
Vitamin E, a potent antioxidant consisting of four isomers each (α, β, γ, δ) of tocopherol (T) and tocotrienol (T3), is found naturally in plant oils at different concentrations. In this study, four semi-purified isonitrogenous and isolipidic (10 %) diets containing canola oil, cold-pressed soybean oil, wheat germ oil, or palm fatty acid distillates (PFAD) as the sole vitamin E source were fed to triplicate groups of red hybrid tilapia (Oreochromis sp.) fingerlings (14.82 ± 0.05 g) for 45 days. Vitamin E concentrations and composition were measured in the muscle, liver, skin, and adipose tissue. Deposition of α-T (53.4-93.1 % of total vitamin E) predominated over deposition of other isomers, except in the liver of fish fed the SBO diet, where α-T and γ-T deposition was in the ratio 40:60. T3 deposition (2.6-29.4 %) was only detected in tissues of fish fed the PFAD diet; adipose tissue was the major storage depot. Fish fed the SBO diet contained significantly more (P tilapia tissues.
In addition to reproduction, gonadotropin-releasing hormone (GnRH) has been postulated to control cholesterol metabolism via cholesterol transport, which is carried out partly by the members of ATP-binding cassette (ABC) transporters G1 (ABCG1) and G4 (ABCG4). However, there is yet to be evidence demonstrating the relationship between these transporters with reference to GnRH neurons. In the present study, we cloned two ABCG1 messenger RNA (mRNA) variants and one ABCG4 mRNA and examined their expression in the brain including GnRH neurons (GnRH1, GnRH2, and GnRH3) in the cichlid tilapia (Oreochromis niloticus). Comparison of nucleotide sequences of the tilapia ABCG1 and ABCG4 with that of other fish species showed that both of these genes are evolutionarily conserved among fishes. ABCG1 and ABCG4 were shown to have high mRNA expressions in the CNS, pituitary, and gonads. In the brain, real-time polymerase chain reaction (PCR) showed that ABCG4 mRNA was higher than ABCG1a in all brain regions including the olfactory bulb (ABCG1=13.34, ABCG4=6796.35; P<0.001), dorsal telencephalon (ABCG1=8.64, ABCG4=10149.13; P=0.001), optic tectum (ABCG1=22.12, ABCG4=13931.04; P<0.01), cerebellum (ABCG1=8.68, ABCG4=12382.90; P<0.01), and preoptic area-midbrain-hypothalamus (ABCG1=21.36, ABCG4=13255.41; P=0.001). Similarly, although ABCG1 mRNA level is much higher in the pituitary compared with the brain, it was still significantly lower compared with ABCG4 (ABCG1=337.73, ABCG4=1157.87; P=0.01). The differential pattern of expression of ABCG1 and ABCG4 in the brain versus pituitary suggests that the two transporters are regulated by different mechanisms. Furthermore, ABCG1 and ABCG4 mRNA expressions were found in all three types of laser-captured GnRH neurons with highly similar percentage of expressions, suggesting that cholesterol efflux from GnRH neurons may require heterodimerization of both ABCG1 and ABCG4.
Dietary organic acids are increasingly being investigated as a potential means of improving growth and nutrient utilization in aquatic animals. A 9-week study was performed to compare equal amounts (2%) of different organic acids (sodium butyrate, acetate, propionate, or formate) on the growth, muscle proximate composition, fatty acid composition, cholesterol and lipid peroxidation, differential cell counts, plasma biochemistry, intestinal short-chain fatty acid (SCFA) level, and liver histopathology to red hybrid tilapia (Oreochromis sp.) (initial mean weight of 2.87 g). A second experiment was performed to determine their effects on lipid peroxidation and trimethylamine (TMA) when added at 1% to tilapia meat and left out for 24 h. The results of the first experiment showed no treatment effect to growth, feeding efficiencies, or muscle fatty acid composition, but all dietary organic acids significantly decreased intestinal SCFA. Dietary butyrate and propionate significantly decreased muscle lipid peroxidation compared to the control group, but the dietary formate treatment had the lowest lipid peroxidation compared to all treatments. Muscle crude protein and lipid in tilapia fed the formate diet were significantly lower and higher, respectively, and showed evidence of stress based on the differential cell counts, significantly higher plasma glucose and liver glycogen, as well as inflammatory responses in the liver. Although a potential benefit of dietary organic acids was a reduction to lipid peroxidation, this could be accomplished post-harvest by direct additions to the meat. In addition, inclusions of butyrate and propionate to tilapia meat significantly decreased TMA, which might be a more cost-effective option to improve the shelf life of tilapia products.
In this paper we have studied the acute toxicity effect of Hg on hybrid tilapia (Oreochromis niloticus). For this, the tissues of tilapia have been digested by means of acids in microwave oven and was analyzed by flameless atomic absorption spectrophotometer (FAAS). We have identified that the levels of Hg varied significantly in different tissues and the metal concentration was in the following order: liver > gills > muscles; of which the maximum level recorded for Hg was 0.799 mg/kg. We have also observed the alterations towards histopathological aspects in the gills and liver of treated fishes were studied using light and electron microscopy, subjected to the exposure of Hg for 24 h and furthermore we have also noticed the extent of the increased alterations during the 96 h of exposure to median lethal concentration LC50 (0.3 mg/L) a severe disorganization of epithelial cells and modifications of the structure of the secondary lamellae. Moreover the severity has also found to increase to sub-lethal concentration (0.03 mgHg/L) in 21 days of exposure; Liver was slightly affected by the contamination of Hg. Ultimately, histopathology is considered as a sensitive technique of bioaccumulation and for the observing the potential damage from Hg exposure.
Introduction: Collagen and gelatin are essential protein in vertebrates and extensively used in various industries. Methods: In this study, acid-solubilized collagen and gelatin were extracted from the scales of three different species of freshwater fish namely Kelah (Tombroides), Tilapia (Oreochromis niloticus) and Snakehead fish (Channidae) and then further quantified using Bradford assay and separated by molecular weight using SDS-PAGE. Results: The extracted collagen in Tilapia fish scale was found to be the highest with 0.018 of protein absorbance among the other three fish; Kelah fish (0.017) and Snakehead fish (0.011). For gelatin, Snakehead fish scales showed the highest amount of total protein concentration followed by Tilapia and Kelah fish with 0.467, 0.144 and 0.037 μg/μL per g, respectively. Based on the SDS-PAGE results, collagen from all the three freshwater fishes were identified as a type 1 (molecular weight approximately from 95 to 130 kDa) collagen. As for gelatin, only gelatin from Snakehead fish scale was identified to be a type 1(molecular weight approximately from 95 to 130 kDa) while the other two freshwater fishes showed no clear band due to high viscosity of the gelatin produced. Conclusion: It can be said that the fishes investigated in this study have a potential to be the alternative source of collagen and gelatin.
Accurately measuring the phenotype at the individual level is critical to the success of selective breeding programs. Feed efficiency is a key sustainability trait and is typically approached through feed conversion ratio (FCR). This requires measurements of body weight gain (BWG) and feed intake (FI), the latter being technically challenging in fish. We assessed two of the principal methods for measuring feed intake in fish over consecutive days: (1) group rearing 10 fish per group and video recording the meals and (2) rearing fish individually on a restricted ration. Juvenile Nile tilapia (Oreochromis niloticus) from the Genetically Improved Farmed Tilapia (GIFT) strain and the Cirad strain were entered into the study (128 GIFT and 109 Cirad). The GIFT strain were reared over three consecutive periods of 7 days each under different feeding, recording, and rearing scenarios (i) in groups fed an optimal ration (g100) or (ii) fed a 50% restricted ration (g50) both with video records of all meals and (iii) reared in isolation and fed a 50% restrictive ration. The Cirad strain were tested similarly but only for scenarios (i) and (iii). All fish were fed twice daily with a calculated ration. Correlations showed the same trends for the GIFT and the Cirad strains. For the GIFT strain, correlations were positive and significant for BWG and FI measured in scenarios (i) and (ii), 0.49 and 0.63, respectively, and FI measured in scenarios (i) and (iii) (0.50) but not for BWG measured in scenarios (i) and (iii) (0.29, NS). The phenotypic correlation estimated for FCR between scenarios (i) and (ii) with fish fed an optimal or a 50% restricted ration was low and not significant (0.22). Feed Conversion Ratio for GIFT fish reared in groups or in isolation and fed with a restricted ration [scenarios (ii) and (iii)] were not significantly correlated either. Social interactions between fish, potentially impacting their efficiency, may explain the results. Therefore, selective breeding programs seeking to improve feed efficiency will need to carefully plan the feeding rate and the rearing system used to estimate FCR in order to optimize selection for the targeted production system.
Freshwater fishes are species that spend their entire live in either freshwater inland or brackish estuaries. The checklist of the fish species should be updated consistently to ensure their diversity is preserved. The study of diversity and distribution of freshwater fishes at Sungai Muar, Kuala Pilah, Negeri Sembilan was carried out on 14 and 15 March 2020 to identify the fish diversity and their development in Sg. Muar, Negeri Sembilan. Trawl (fish collections), weighing machine and ruler (morphometric observations) was used during experiment. Fish species found during this study include Oreochromis mossambicus (Family Cichlidae), Hemibagrus nemurus (Family Bagridae), Homaloptera tweediei (Family Balitoridae), Notopterus notopterus (Family Notopteridae), Oxyeleotris marmorata (family Eleotridae), and five species of Family Cyprinidae, which were Mystacoleucus marginatus, Osteochilus haseltii, Cyclocheilichthys apogon, Barbonymus schwanenfeldii and Hampala microlepidota. Fishes from family Cyprinidae was dominated the area with a total of 102 individuals found. The statistical analysis shows the diversity (H’)=1.826, richness (R’)=2.004 and evenness (E’)= 0.5645 of freshwater fish at Sungai Muar, respectively. The most dominant species found was Mystacoleucus marginatus with 50 individuals and the least abundant species were Barbonymus schwanenfeldii, Homaloptera tweediei and Oxyeleotris marmorata with one individual only. The length-weight regression shows a positive allometric growth with ‘b’ value is higher than 3 at both stations; 3.0118 (Station 1) and 3.4409 (Station 2). It shows that the fish becomes heavier as its length increases. This data provides information about the fish habitat in Sungai Muar and can be used to update the checklist of fish species in Sg Muar. The data obtained provides information about the fish habitat in Sungai Muar which could be useful for the planning of fishing activities Other than that, it also important as a guideline for future research and conservation purposes especially in Negeri Sembilan.
Understanding the genetic mechanism of osmoregulation is important for the improvement of salt tolerance in tilapia. In our previous study, we have identified a major quantitative trait locus (QTL) region located at 23.0 Mb of chrLG18 in a Nile tilapia line by QTL-seq. However, the conservation of these QTLs in other tilapia populations or species is not clear. In this study, we successfully investigated the QTLs associated with salt tolerance in a mass cross population from the GIFT line of Nile tilapia (Oreochromis niloticus) using a ddRAD-seq-based genome-wide association study (GWAS) and in a full-sib family from the Malaysia red tilapia strain (Oreochromis spp) using QTL-seq. Our study confirmed the major QTL interval that is located at nearly 23.0 Mb of chrLG18 in Nile tilapia and revealed a long QTL cluster across chrLG18 controlling for the salt-tolerant trait in both red tilapia and Nile tilapia. This is the first GWAS analysis on salt tolerance in tilapia. Our finding provides important insights into the genetic architecture of salinity tolerance in tilapia and supplies a basis for fine mapping QTLs, marker-assisted selection, and further detailed functional analysis of the underlying genes for salt tolerance in tilapia.
The development of glyphosate-resistant genetically modified organisms (GMO) has increased the use of herbicide glyphosate by several magnitudes in recent years. It is now the most commonly used pesticide globally that affects aquatic habitats, especially fish. This study aims to add new knowledge on the effect of technical grade glyphosate on several toxicity parameters and to identify the most effective parameter in predicting technical grade glyphosate chronic toxicity (seven weeks) to fish, especially Malaysia's heavily farmed red tilapia. The results show that a relatively high concentration of technical grade glyphosate is needed to induce significant changes in all tested parameters. However, the results also indicate that the bodyweight index is the most sensitive toxicity parameter in that a reduction in body weight was observed at 25 mg/L of glyphosate. Negative correlations between the glyphosate concentration and toxicity parameters such as specific growth rate (SGR), hepato-somatic index (HIS), and gonado-somatic index (GSI) were observed. The fish condition factor and feed conversion ratio were found not to be affected at the highest glyphosate concentration tested (150 mg/L). To conclude, crossbred red tilapia (O. niloticus × O. mossambicus) is one potential species for evaluating the toxic effects of technical grade glyphosate on fish.
Vibrio parahaemolyticus is a causative agent of foodborne outbreaks associated with the consumption of raw or under-cooked seafood. This study aimed to quantify and detect the occurrence of V. parahaemolyticus in freshwater fish by performing Most Probable Number (MPN) method in combination with Polymerase Chain Reaction (PCR). In this study, a total of 20 red tilapia (Oreochromis sp.) were collected from nearby local wet markets. Polymerase Chain Reaction (PCR) assay targeting the toxR gene in V. parahaemolyticus was performed, with the expected DNA amplification size of 368 bp. MPN analysis showed that the estimated microbial load of V. parahaemolyticus were more than 1100 MPN/g. The result of the PCR assay confirmed the presence of V. parahaemolyticus in 90% of the isolates. This positive detection elucidated the presence of food-borne bacteria in freshwater fish from local wet-market which may affect not only the health of fish stocks but also raise public health concerns.
A survey was conducted to determine the diversity of fish in Pergau Lake, Jeli, Kelantan, Malaysia from 2 September to 18 October of 2016. Fish samples were collected at seven random sampling stations around the lake by using setting trap method. The collected samples were preserved in 10% formalin solution and delivered to the laboratory for further identification process. Fourteen species, namely as Hemibagrus nemurus, Hampala macrolepidota, Clarias batrachus, Channa striata, Cyprinus carpio, Poropuntius smedleyi, Pangasius sp., Oreochromis niloticus, Oreochromis mossambicus, Leptobarbus hoevenii, Neolissochilus hexagonolepis, Tor tambroides, Osteochilus hasselti and Neolissochilus soroides, comprising of six families were collected during this study. From this study, family of Cyprinidae was the dominant species in Pergau Lake with exactly 50% of catch percentage, followed by family of Bagridae (29%), Cichlidae (10%), Clariidae (5%), Channidae (3%) and Pangasiidae (3%). This study shows that there is still a diversity of fish species in Pergau Lake, showing that the water and its environmental condition is very good.
The preliminary ichthyotoxic test on all parts of Syzygium malaccense (Myrtaceae) revealed that the leaves fraction was the most ichthyotoxic against tilapia-fish (Tilapia oreochromis). Three compounds, namely ursolic acid (1), β-sitosterol (2) and sitost-4-en-3-one (3), were isolated and their structures were elucidated with the aid of spectroscopic data and comparison with previously reported investigations. However none of these compounds gave any significant ichthyotoxicity. The volatile constituents of the leaves and fruit were determined by Gas Chromatography-Mass Spectrometer (GC-MS), with 180 and 203 compounds being identified in the aroma concentrates, respectively.
The development of genomic markers is described for Nile tilapia, Oreochromis niloticus, using the Diversity Arrays Technology (DArT) genotype-by-sequencing platform. A total of 13 215 single nucleotide polymorphism (SNP) markers and 12 490 silicoDArT (dominant) markers were identified from broodstock of two selective breeding programs [Genetically Improved Farmed Tilapia (GIFT) strain from Malaysia and the Abbassa strain from Egypt]. Over 10 000 SNPs were polymorphic in either strain, and 2985 and 3087 showed strain-specific polymorphisms for the GIFT and Abbassa strains respectively. We demonstrate the potential utility of these markers for rapid genomic screening and use in breeding programs.
A feeding trial was conducted to investigate the effect of mushroom supplementation as a prebiotic compound in an insect-based diet on the growth performance and feed utilization of red Tilapia (Oreochromis sp.). A total of 120 fingerlings were divided in triplicates for each treatment. Four experimental diets were offered to the fishes within a 56 days treatment period. Out of the four diets, three contained mushroom stalk meal (MSM) supplementation at various levels of inclusion of prebiotic compound (0.5% MSM; 1.0% MSM; 1.5% MSM) and the fourth a control diet without MSM inclusion. During the growth test, fish receiving diet containing prebiotic showed significantly higher (p<0.05) mean individual body weight in comparison with the control diet. The best effect was obtained in fish fed with Diet 2, where the specific growth rate (SGR) was 1.74%, feed conversion ratio (FCR) was 0.58, protein efficiency ratio (PER) was 5.17 and survival was 93.33%. No significant differences (p>0.05) were observed in whole body protein and ash contents among the fish feeding on these diets. All water quality parameters showed no significant difference (p>0.05) in all treatments. The result of this feeding trial indicated that the 10% supplementation level of MSM as a prebiotic for tilapia could be used in the insect-based diet, Zophobas morio.