In this study,chondroitin sulfate was extracted from Oreochromis niloticus bones(OCS)and isolated to three fractions(OCS-1,OCS-2,and OCS-3).The physicochemical properties and structure characterization including monos...In this study,chondroitin sulfate was extracted from Oreochromis niloticus bones(OCS)and isolated to three fractions(OCS-1,OCS-2,and OCS-3).The physicochemical properties and structure characterization including monosaccharide,disaccharide compositions,molecular weight(Mw)of OCS were determined by HPAEC,HPLC-SAX,HPGPC,FT-IR spectra,and 1D/2D NMR.Moreover,their thermal properties,crystalline structure,and microstructure were also analyzed.Results showed that their Mw were between 10 kDa and 50 kDa.CS-6 was the predominant disaccharide unit in four OCS,and the CS-4/CS-6 ratios were close to CS from shark cartilage.Besides,the results of antioxidant activity showed that different fractions of OCS had a distinct DPPH radical,hydroxyl radical,and ABTS+radical scavenging activity.OCS-1 has the highest scavenging activities in DPPH and hydroxyl radical compared with other fractions,which showed a higher medicinal value.Those findings may lay some theoretical basis for the potential application development of OCS.展开更多
The optimization of aquaculture production requires the selection of efficient strains. Thus, genetic improvement has become one of the important levers to boost the development of aquaculture. The objective of this s...The optimization of aquaculture production requires the selection of efficient strains. Thus, genetic improvement has become one of the important levers to boost the development of aquaculture. The objective of this study was to carry out genetic characterization of Nile tilapia Oreochromis niloticus, one of the most cultivated fish species in Senegal, in order to select an efficient strain to optimize local fish production. Thus, fish from five different populations (Richard-Toll, ANA, ITACA, Mbodiene and Sauvage) were analyzed, with 15 individuals per population. Genetic diversity and population structure were assessed using molecular genetic analyses by sequence characterized amplified region (SCAR) and microsatellite (SSR) markers. The analyses of the SCARII marker were conducted on four populations (ANA, ITACA, Sauvage and Mbodiene) while microsatellite analyses were conducted on all five populations. The results show high levels of polymorphism of SSR markers, and a high level of observed heterozygosity (Ho), indicating a high within-population genetic variability. These results are in agreement with the AMOVA results, which indicated a high within-population genetic variability (94%). The genetic structure analysis by DAPC indicates that the five populations analyzed are structured into four groups, which are highly heterogeneous because they share common allele individuals. The analysis of the genetic structure by AMOVA showed a low degree of differentiation between the populations (6%), in agreement with the genetic differentiation index (Fst = 0.059). The heterogeneity of studied populations implies a genetic flow over time, which may have existed between the original populations. The overall negative Tajima D values and low genetic differentiation indicate an excess of rare mutations in the populations studied, resulting from a recent population expansion from a limited number of initial breeders isolated in locale hatcheries. Thus, further studies with a much larger panel of markers are required to better differentiate the strains and identify the most efficient ones for sustainable local aquaculture production.展开更多
Dried fish are susceptible to bacteria and fungi attack and are liable to chemical changes which cause losses in quality and reduction of shelf-life. It is important therefore to maintain the quality of fish because c...Dried fish are susceptible to bacteria and fungi attack and are liable to chemical changes which cause losses in quality and reduction of shelf-life. It is important therefore to maintain the quality of fish because continuous consumption of contaminated fish and their products may predispose consumers to health hazards. Maintenance of high quality fish therefore calls for adequate and effective preservation techniques. The study examined the effectiveness of essential oils of Ocimum basilicum and Ocimum gratissimum from two Agro-ecological zones of Cameroon in limiting the microbial proliferation and preserving the quality of smoke-dried Oreochromis niloticus fish stored at 25˚C for two months. The plant materials were harvested from the Western Highlands and Monomodal Humid Forest agroecological zones of Cameroon. Extraction of the essential oil from the plants was done by hydro-distillation. The fish species (Oreochromis niloticus) used in this study was chosen based on a survey study on the most consumed species of freshwater smoke-dried fish in the Western Highlands and Monomodal Humid Forest Agro-ecological zones of Cameroon. Heterotrophic bacteria counts, fungi counts and Enterobacteriaceae counts were used to assess the level heterotrophic bacteria, fungi and Enterobacteriaceae respectively in the fish samples during storage and were done by culture techniques using total plate count agar, potato dextrose agar and violet red bile glucose agar respectively. Total volatile basic nitrogen, peroxide value, and thiobarbituric acid reactive substance assays were used as spoilage indices to assess the nutritional quality of the fish during storage. From the survey study, Oreochromis niloticus was the most consumed smoke-dried fish in the Western Highlands (35.45%) and Monomodal Humid Forest (34.55%) agroecological zones. All the EOs caused a significant reduction in the microbial loads, total volatile basic nitrogen, peroxide value, and thiobarbituric acid reactive substance of smoke-dried Oreochromis niloticus as storage progressed. However, the reduction in these values was more pronounced in samples treated with essential oils of O. gratissimum from the Western Highlands, with heterotrophic bacteria, fungi and Enterobacteriaceae counts being 5.89, 6.97 and 4.59 log<sub>10</sub> cfu/g respectively at the end of the storage period. This was followed by essential oils of O. gratissimum from the Monomodal Humid Forest with heterotrophic bacteria, fungi and Enterobacteriaceae counts being 6.11, 7.79 and 4.86 log<sub>10</sub> cfu/g respectively at the end of the storage period. Also, essential oils of O. gratissimum from the Western Highlands was more effective in preserving the fish quality as lowest total volatile basic nitrogen (12.29 mg/100g), peroxide value (2.79 mEq O<sub>2</sub>·Kg<sup>−1</sup>) and thiobabituric reactive substance (1.695 mg MDA/Kg) values were observed for fish samples treated with this extract at the end of the storage period. This was followed by essential oils of O. gratissimum from the Monomodal Humid Forest with total volatile basic nitrogen (14.95 mgN/100g), Peroxide value (3.23 mEq O<sub>2</sub>·Kg<sup>−1</sup>) and thiobabituric reactive substance (2.354 mg MDA/Kg) at the end of the storage period. From the results obtained, essential oils from O. gratissimum were more effective than that from O. basilicum in the two agroecological zones and should be considered as natural alternative to chemical preservatives for further application in food preservation.展开更多
This study was carried out in 2022 at the Itato agriculture community estate of fish hatchery in eastern Senegal with the aim of finding an alternative method to 17-α-methyl testosterone (MT) by using Garcinia kola ...This study was carried out in 2022 at the Itato agriculture community estate of fish hatchery in eastern Senegal with the aim of finding an alternative method to 17-α-methyl testosterone (MT) by using Garcinia kola “Bitter kola” powder to obtain Oreochromis niloticus male sex populations. 1800 fry of average size between 0.01 and 0.02 g were distributed in 12 aboveground tanks of 1 m3 each at a rate of 150 individuals/tank, following 6 duplicate treatments. The negative (B1 and B2) and positive (B3 and B4) control diets, to which between 0 and 60 mg/kg of 17alpha-methyl testosterone had been added respectively, were mixed with industrial feed containing 40% protein;the tank diets (B5 and B6), (B7 and B8), (B9 and B10) and (B11 and B12) contained 10 g, 20 g, 30 g and 40 g of Garcinia kola powder respectively for 1 kg of industrial feed con-taining 40% protein. These different treatments resulted in high proportions of males in the order of 97.03%;98.09% for the hormone and proportions of 94.03%;93.26% for 20 g of Garcinia kola extracts. In terms of weight growth, the best average weights for the hormone and Garcinia kola were 0.896 g and 0.980 g respectively. With regard to fish survival, the following results were recorded: 95.53% and 94.56% respectively for additions of 20 g and 30 g of Garcinia kola extracts to the feed supplied to the fish. On the other hand, a significant difference in the mortality rate of 35% and 5% respectively for the conventional hormone and 20 g of Garcinia kola extracts was observed. To conclude the study, it is recommended that further studies be carried out to determine the quality of the flesh, their life stages and the profile of the amino acids present in their proteins.展开更多
Irrigation of fish farms with agricultural drainage water may affect cultured fish species. So, the present study utilizes antioxidants supplemented diet to overcome deterioration of drainage water and its negative ef...Irrigation of fish farms with agricultural drainage water may affect cultured fish species. So, the present study utilizes antioxidants supplemented diet to overcome deterioration of drainage water and its negative effect on fish. The studied groups are fish cultured in dechlorinated tap water as control group or drainage water and fed commercial basal diet. While, the other studied groups represented by Oreochromis niloticus fish cultured in drainage water and fed either commercial diet supplemented with vitamin C (5 g/kg diet) or fennel (5 g/kg diet) for 12 weeks. Results of the water physico-chemical parameters of all studied treatments revealed deterioration of the drainage water with a decrease in dissolved oxygen and an increase in pH, total hardness, total alkalinity, salinity, ammonia, nitrite and heavy metals (Cu, Pb and Cd) with significant differences (P ≤ 0.01) in comparison to that of the control dechlorinated tap water group. Data clarified also that Oreochromis niloticus cultured in drainage water showed a decrease in growth rate accompanied by deterioration of fish meat quality. However, fish reared in the same drainage water for the same exposure period and fed vitamin C or fennel supplemented basal diet (5 g/kg diet) recorded values of the studied parameters more or less similar to that of control group fish. Data of the present study, empowered aquaculturist to supplement fish rations with fennel or vitamin C as antioxidants to improve fish growth rate, meat quality as well as protect fish against heavy metals toxicity that could threat Human Being.展开更多
为比较星洲红鱼(Singapore red tilapia)和奥尼罗非鱼(Oreochromis niloticus)的生长和肌肉营养特性,实验利用两种鱼的不同体色将其混养在同一池塘中,在相同的环境条件和养殖管理下研究其生长特性,并分析肌肉营养成分。结果表明:两种罗...为比较星洲红鱼(Singapore red tilapia)和奥尼罗非鱼(Oreochromis niloticus)的生长和肌肉营养特性,实验利用两种鱼的不同体色将其混养在同一池塘中,在相同的环境条件和养殖管理下研究其生长特性,并分析肌肉营养成分。结果表明:两种罗非鱼生长在前60 d无差异,60 d后星洲红鱼的体长、体质量日增长和特定生长率均大于奥尼罗非鱼,且差异显著(P<0.05)。据此得到了星洲红鱼和奥尼罗非鱼的体长(L)、体质量(W)生长与养殖天数(d)的回归方程。星洲红鱼含肉率高于奥尼罗非鱼9.65%(P<0.05),肌肉水分高于奥尼罗非鱼,蛋白质、粗脂肪和灰分含量均低于奥尼罗非鱼,其中脂肪含量差异显著(P<0.05),其他不显著。两种罗非鱼肌肉的氨基酸组成全面,氨基酸组成均符合FAO/WHO的理想模式,除精氨酸含量有差异外,其他氨基酸含量稍有差异但不显著。星洲红鱼和奥尼罗非鱼肌肉EAA/TAA、EAA/NEAA、DAA/TAA和EAAI分别为41.04%和40.95%,70.00%和69.34%,40.71%和39.08%,67.46%和67.08%,差异不显著。星洲红鱼、奥尼罗非鱼肌肉∑SFA和∑UFA分别为28.03%和28.60%,63.87%和61.38%,各脂肪酸含量除C14:0和C18:2外,其他含量差异不显著。研究表明,星洲红鱼和奥尼罗非鱼生长快、营养丰富、食用价值高,是优质淡水鱼类养殖品种,其中星洲红鱼含肉率高,生长快,养殖效益明显。展开更多
The efficacy of Endocrine Disrupting Compounds (EDCs), 17β-estradiol was tested on the fish Oreochromis niloticus in order to understand the intersex relationship of fish, in which sequential hermaphrodism can consis...The efficacy of Endocrine Disrupting Compounds (EDCs), 17β-estradiol was tested on the fish Oreochromis niloticus in order to understand the intersex relationship of fish, in which sequential hermaphrodism can consist of a male changing into a female (protandry) or a female changing into a male (protogyny). The fish were equally divided into 3 groups. The first group was the control group;the second and third groups were treated with 10 and 100 mg L-1 of 17β-estradiol, respectively, for 30 days. The overall result in this experiment had no significant effect on the growth parameters. Among the two treated groups, the low concentration group shows results similar to those of the control groups. The high concentration group shows changes to the male reproductive system with the appearance of the testis-ova present resulting in an intersex condition of the male gonads. With this experiment, it can be concluded that 17β-estradiol at high concentration reveals positive changes towards the male reproductive system of the fish, Oreochromis niloticus.展开更多
Nitrogen (N) and phosphorus (P) wastes produced by Nile tilapia Oreochromis niloticus L. fed Azolla, an aquatic atmospheric nitrogen fixing fern, was evaluated for 90 days in pond experiment. Six isonitrogenous (29.2%...Nitrogen (N) and phosphorus (P) wastes produced by Nile tilapia Oreochromis niloticus L. fed Azolla, an aquatic atmospheric nitrogen fixing fern, was evaluated for 90 days in pond experiment. Six isonitrogenous (29.2% crude protein) and isoenergetic (16.9 Kj·g–1) diets A0, A10, A20, A30, A40 and A50, containing 0%, 10%, 20%, 30%, 40% and 50% of Azolla meal (AM) respectively, as partial fishmeal (FM) substitutes, was provided to experimental fish. The Azolla-free diet A0 served as a control. Fish specific growth rate (SGR) was higher with the control diet, the lower values being obtained in A50-fed fish (P Azolla could be used in diet to sustain Nile tilapia growth and as “environmentally-friendly” ingredient to limit P loss, while providing N to the field, beneficially in tropical marshland pond where this nutrient is already limiting.展开更多
Through PCR amplification, 5' flanking region and partial open reading frame(ORF) of gene of Nile tilapia(Oreochromis niloticus) was cloned by PCR amplification. Sequence analysis showed that no difference was fou...Through PCR amplification, 5' flanking region and partial open reading frame(ORF) of gene of Nile tilapia(Oreochromis niloticus) was cloned by PCR amplification. Sequence analysis showed that no difference was found in known functional regions. This study was to construct and identify the mammalian expression vector of pEGFP-β-actin and to detect whether it could express in HEK 293T cell line. pEGFP-β-actin was transfected into HEK 293T cells with Lipofectamine 2000. The results showed that correct construction of recombinant pEGFP-β-actin has been shown by restriction enzyme digestion. The expression of gene in HEK 293T cells could be observed under microfluoroscope. pEGFP-β-actin could repress EGFP protein in HEK 293T cells. The results showed that β-actin gene promoter possessed effective transcription activities in eukaryotic cells. The work laid foundations for further study on the gene engineering and autotransgenic tilapia.展开更多
The aim of the study was to investigate the antibacterial potential of garlic(Allium sativum),pinus(Pinus elliottii),eucalyptus(Eucalyptus sp.),yerba mate(Ilex paraguariensis)and guava tree(Psidium guajava Linn.)in vi...The aim of the study was to investigate the antibacterial potential of garlic(Allium sativum),pinus(Pinus elliottii),eucalyptus(Eucalyptus sp.),yerba mate(Ilex paraguariensis)and guava tree(Psidium guajava Linn.)in vitro and the effect of yerba mate supplementation on Oreochromis niloticus physiology and resistance to Aeromonas hydrophila.The in vitro antibacterial potential of the plants was verified by the minimum inhibitory concentration(MIC)method and by the antimicrobial sensitivity test(TSA).The in vivo assay was performed using diet supplementation with yerba mate and challenge with A.hydrophila.After the supplementation and challenge periods biochemical,immune and physiological parameters were evaluated.The in vitro assays showed that only yerba mate presented antibacterial potential against A.hydrophila and no one of the plant extracts were effective against Streptococcus agalactiae.The use of yerba mate in the diet did not influence the immune and metabolic status of O.niloticus.Also,the supplementation did not act as a growth promoter for the fishes.Considering the challenge of O.niloticus with A.hydrophila,the yerba mate did not improve the resistance of the fishes to the bacteria.The yerba mate extract presented potential to be used as an antibacterial agent for fish diseases.Also,more detailed studies are necessary to stablish effective doses and times required for fish treatments.展开更多
The approximate general composition and the fatty acid profile of Nile tilapia fed Azolla-diets in ponds were studied for 90 days. Six isonitrogenous (29.2% CP) and isoenergetic (16.9 kJ·g>sup>-1) diets wer...The approximate general composition and the fatty acid profile of Nile tilapia fed Azolla-diets in ponds were studied for 90 days. Six isonitrogenous (29.2% CP) and isoenergetic (16.9 kJ·g>sup>-1) diets were formulated to contain 0% (A0), 10% (A10), 20% (A>sub>20), 30% (A30), 40% (A40) and 50% (A50) of Azolla meal (AM), as partial fish meal (FM) substitutes. Diet A0 without AM served as a control. Fish growth decreased as AM level exceeded 20% in diets (P 0.05). Crude lipid was significantly lower in fish fed A50 and significant differences were also found in crude ash (P 20, A30 and A50. High level of the fern reduces growth without negatively affecting fatty acid in fish. Fish PUFA, especially the (n - 3) fatty acids, are affected positively, even when fed 50% AM, which is good for the quality of the fish produced in regard to the benefits for the health of consumers.展开更多
Concentrations of OCP(Organochlorine Pesticide)residues were determined in cultured Nile tilapia(Oreochromis niloticus)fish in target stations within 1st order wetland of River Kuja,Kenya,between February-November,201...Concentrations of OCP(Organochlorine Pesticide)residues were determined in cultured Nile tilapia(Oreochromis niloticus)fish in target stations within 1st order wetland of River Kuja,Kenya,between February-November,2017.The aim was to assess the residue levels in wild and pond cultured fish within a heavily populated agricultural area of South Western Kenya.Biota samples were analysed for selected HCHs(Hexachlorocyclohexane)isomers,DDT(Dichlorodiphenyltrichloroethane)and metabolites and cyclodienes pesticide residues using GC-ECD(Gas Chromatography Equipped with Electron Capture Detector).Most of OCPs observed were BDL(Below Detection Limit)to detectable levels.Larger percentages(>50%)of DDTs and HCHs were BDL and exhibited consistency,with significant(p<0.05)differences in mean contamination levels in fish within the wetland,with average muscle tissue pesticides concentrate ranging between 0.229-2.541mg/kg for Nile tilapia.Most dominant isomer in target species was Lindane(g-HCH)(3.417±0.983mg/kg)and Endosulfans.Mean Endosulfan sulfate was 2.499±0.071mg/kg d.w.and most frequently detected,and Methoxychlor(2.235±1.459mg/kg),respectively.Mean Aldrin and Dieldrin was 2.028 and 0.574mg/kg d.w.Concentration for DDT and its metabolites was 0.27-3.71mg/kg for p,p’-DDE(DichlorodiphenylDichloroEthene),BDL-1.098 for p,p’-DDD(DichloroDiphenylDichloroEthane),and 0.105-3.518mg/kg for p,p’-DDT with significant differences in mean values and ranges whose levels were below the WHO(World Health Organization)maximum acceptable thresholds of 0.2,2,20 and 5.0mg/kg in fish and sea food.Interventions and monitoring need up-scaling in minimizing public health risks posed by consumption and exposure.展开更多
Fishes are suitable for sun drying and smoking. But their high contains of unsaturated fatty acids mak</span><span style="font-family:Verdana;">e</span><span style="font-family:Verd...Fishes are suitable for sun drying and smoking. But their high contains of unsaturated fatty acids mak</span><span style="font-family:Verdana;">e</span><span style="font-family:Verdana;"> them very prone to lipid oxidation. However, some plants are rich in natural antioxidants and have been shown to be potent inhibitors of lipid oxidation during processing of meat. The effect of three aqueous plants extracts on lipid stability of </span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">Oreochromis niloticus</span></i><i><span style="font-family:Verdana;"></i></span></i><span style="font-family:Verdana;"> collected in Far-North Cameroon during processing was evaluated. Results show the high nutritious of these fish with high levels of proteins, lipid and ash (71.02</span><span style="font-family:Verdana;">%</span><span style="font-family:Verdana;">, 13.71</span><span style="font-family:Verdana;">%</span><span style="font-family:Verdana;"> and 10.65%, respectively). It has been observed that oleic acid (C18:1), followed by palmitic acid (C16:0) and linoleic acid (C18:2) are the most dominant fatty acids present in </span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">Oreochromis niloticus</span></i><i><span style="font-family:Verdana;"></i></span></i><i><span style="font-family:""> </span></i><span style="font-family:Verdana;">lipids. Their lipid also showed a much higher content of omega-3 polyunsaturated fatty acids (PUFA) compared to omega 6 PUFA. The total phenolic contents (TPC) of the three plants ranged from 12</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;">150 to 16</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;">050 mg/100</span><span style="font-family:""> </span><span style="font-family:Verdana;">g. The leaves of </span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">Moringa oleifera</span></i><i><span style="font-family:Verdana;"></i></span></i><span style="font-family:Verdana;"> exhibited </span><span style="font-family:Verdana;">the </span><span style="font-family:Verdana;">higher content of TPC. The results of iodine, peroxide value and thiobarbituric acids test were revealed that the aqueous extracts of the tree plants had antioxidant properties. These plants extracts inhibit lipid oxidation of </span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">Oreochromis niloticus</span></i><i><span style="font-family:Verdana;"></i></span></i><span style="font-family:Verdana;"> during processing. Increasing of the concentration of plant extracts enhanced their antioxidant activities and the highest oxidation inhibitor was obtained at 30</span><span style="font-family:""> </span><span style="font-family:Verdana;">g/l. </span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">Moringa oleifera</span></i><i><span style="font-family:Verdana;"></i></span></i><span style="font-family:Verdana;"> leaves inhibit highly the lipid oxidation of </span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">Oreochromis niloticus</span></i><i><span style="font-family:Verdana;"></i></span></i><span style="font-family:Verdana;">.展开更多
Exposure to heavy metals is an important environmental problem resulting from anthropogenic activities. The aim of this study was the evaluation of some heavy metals as cadmium (Cd), lead (Pb), chromium (Cr) and alumi...Exposure to heavy metals is an important environmental problem resulting from anthropogenic activities. The aim of this study was the evaluation of some heavy metals as cadmium (Cd), lead (Pb), chromium (Cr) and aluminum (Al), in muscle of fresh water fish Oreochromis niloticus from ten provinces all over Egypt to assess its possible hazards on fish and consumers. The analyzed metals could be detected in all examined samples and their order was Pb > Cr > Cd > Al. A positive correlation between Al concentration and the fish length was observed. The concentrations of Pb, Cd and Cr in fish samples were several times higher than their concentration in water and the bioaccumulation Factor (BAF) ranged from 8.22 - 122.6. The estimated weekly intake of Cd, Pb and Cr for a 70 kg person consuming fish in Egypt (7.94, 15.84 and 9.8 μg) is well below the Provisional Permissible Tolerable Weekly Intake (PTWI) recommended by FAO/WHO. Although heavy metal levels in Egypt exceed the maximum permissible limits recommended by Egypt and WHO in some fish samples, the consumption of Nile O. niloticus from Egypt is safe on human health.展开更多
Two 90-day experiments were conducted in the same period in tanks and in earthen ponds to study the effects of culture systems on growth and fatty acid (FA) of Nile tilapia (Oreochromis niloticus L.) fingerlings (mean...Two 90-day experiments were conducted in the same period in tanks and in earthen ponds to study the effects of culture systems on growth and fatty acid (FA) of Nile tilapia (Oreochromis niloticus L.) fingerlings (mean weight: 16.3 g) fed Azolla, as partial replacement for fish meal (FM). Diets were isonitrogenous (29.2% CP) and isoenergetic (16.9 kJ·g-1) containing 0% (A0), 10% (A10), 20% (A20), 30% (A30), 40% (A40) and 50% (A50) of Azolla meal (AM) respectively. Diet A0, without AM, acted as a control. In both experiments, fish growth decreased as AM level increased in diets (P P 30-A50). Interestingly, those fish were rich in eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3). Consequently, the n-3/n-6 values decreased in tanks, whereas an increasing trend was found in ponds, and values were significantly higher in ponds than in tanks (0.35 - 0.53 vs. 0.08 - 0.17). The results suggest raising Nile tilapia with Azolladiets in ponds to improve growth and produce fish with a better FA composition, for the wellbeing of consumers.展开更多
The present study deals with the effect of exogenous treatment of O. niloticus females with L-thyroxine (T4) on the development of the digestive system during larval rearing, and its subsequent effect on larval growth...The present study deals with the effect of exogenous treatment of O. niloticus females with L-thyroxine (T4) on the development of the digestive system during larval rearing, and its subsequent effect on larval growth and survival. The development of the digestive tract and accessory glands was investigated histologically and histochemically in the developing O. niloticus larvae, from control and T4-treated spawners. During yolk-sac absorption, the digestive system of the fish underwent further differentiation and the rudimentary alimentary canal became segmented into four different histological regions: the buccopharynx, oesophagus, stomach and intestine. The injection of females O. niloticus with thyroxine (1 or 10 μg T4/g BW) greatly enhanced the development of the digestive tract and accessory glands of larvae as indicated by the quantitative and qualitative changes of the mucus composition from predominantly neutral to a mixture of neutral and acid mucosubstances, or acid mucosubstances occurred during the rearing period for the larvae produced from T4-treated females. This may be due to the direct effect of exogenous thyroxine, which might have been transferred from maternal circulation into the oocytes and larvae, on the synthesis of proteins, which increased with larval development. Thus, thyroxine directly or indirectly improved O. niloticus larval growth, since a marked increase in both, length and weight of larvae occurred during the experimental period. In addition, larvae from treated females also gave a significantly higher survival rate than that of control. It could be concluded that exogenous T4 in maternal circulation might have been transferred into oocytes and larvae. The transferred thyroid hormone appears to play some role in the early development of larvae and may confer a distinct advantage for the growth of the offspring of the Nile tilapia, O. niloticus.展开更多
It is estimated that quarter to half a million specimens of the Nile crocodile (Crocodylus niloticus Laurenti, 1768) live in liberty. Ranching crocodiles for their skins has been successfully implemented in several Af...It is estimated that quarter to half a million specimens of the Nile crocodile (Crocodylus niloticus Laurenti, 1768) live in liberty. Ranching crocodiles for their skins has been successfully implemented in several African countries but also in Israel. Recently, in one of these ranches, an increased mortality of crocodile eggs was observed and it was thought that insects were causing their death. Two crocodile eggs were kept together with 100 adults of Tribolium castaneum (Herbst, 1797), while the third egg was kept without beetles. No food for beetles was added to the boxes. The eggs were observed twice a month for any kind of changes on their surface. After two months, at least 39 holes were observed in one egg and 146 on the second egg, which was exposed to beetles, while no holes could be seen in the control egg. Some of the holes were deep enough to see the inner layers of the egg. There is enough evidence to believe that adults of T. castaneum are able to damage the eggs of the Nile crocodile and in some cases lead to their death;measures should be taken to protect the eggs from this and similar species of beetles.展开更多
Native polyacrylamide gel electrophoresis have been used to analyze malate dehydrogenase (MDH), acid phosphatase (Acph) and peroxidase (Px) isoenzymes in different tissues (liver, kidney, muscle and heart) of the tila...Native polyacrylamide gel electrophoresis have been used to analyze malate dehydrogenase (MDH), acid phosphatase (Acph) and peroxidase (Px) isoenzymes in different tissues (liver, kidney, muscle and heart) of the tilapia fish, Oreo- chromis niloticus in order to study the tissue specificity of these isoenzymes. Three, two and one fractions have been recorded respectively for the three isoenzymes in different studied tissues. The MDH-1 and MDH-2 have been ex- pressed only in muscle and heart while MDH-3 has been expressed in all studied tissues. The percentage amount of MDH in general varied significantly between muscle and different studied tissues. With respect to acid phosphatase, the percentage amount of the total enzyme showed significant difference between liver and muscle and that this variation may be due to higher gene activity in liver. Peroxidase isoenzyme was recorded in liver and heart only with significant increase in liver. The kidney was the least among the studied tissues in showing gene expression for the studied isoenzymes and therefore, liver, heart and muscle tissues are better applicable in studying the isoenzymatic profiles for fish physiology and systematics.展开更多
This study was designed to investigate the possible variation in bioaccumulation of heavy metals (lead, cadmium, zinc, cobalt, chromium, nickel, and manganese) in the tissue of harvested Oreochromis niloticus (tilapia...This study was designed to investigate the possible variation in bioaccumulation of heavy metals (lead, cadmium, zinc, cobalt, chromium, nickel, and manganese) in the tissue of harvested Oreochromis niloticus (tilapia) and the associated fungi from vials treated with soil from e-waste dumpsite and soil without e-waste. E-waste is electronic waste which contains valuable metals as well as potential environmental contaminants. The heavy metals in soil and fish samples were determined using flame atomic absorption spectrophotometer (AAS) after homogeneity and digestion of samples. The associated fungi were identified using standard microbiological methods. The genera of the associated fungi were: Penicillium, Candida, Articulospora, Aspergillus, Aspergillus, Aspergillus, Rhizopus, Mucor, Zoopage, Varicosporium and Rhodoturula. The quantity of fungi isolated from each pollution treatments showed that the number of fungi were inversely proportional to the quantity of e-waste soil pollution and directly proportional to the quantity of soil without e-waste pollution. The occurrence of the fungi species revealed that the untreated (control) vial had the highest occurrence (191) while the lowest occurrence (103) occurred in the vial polluted with the highest quantity of soil from e-waste dumpsite. The pH and the biochemical oxygen demand (BOD) of the vials were significantly affected by the pollutions. Variations were also observed in the bioaccumulation of the heavy metals by Oreochromis niloticus. Cadmium (0.01 mg/kg) and nickel (0.02 - 0.08 mg/kg) were the least recorded metal in the tissue of the fish while cobalt was not detected after the five weeks period. The sequence of the heavy metals concentrations in Oreochromis niloticus tissue samples was Zn > Mn > Pb > Cr > Ni > Cd > Co. The accumulation of the metals in the fish tissue were, however, lower than the international maximum guidelines, except for manganese (0.29 - 3.13 mg/kg) that exceeded the 0.01 - 0.05 mg/kg threshold levels for manganese by Federal Environmental Protection Agency (FEPA). Protecting the environments from toxic metals is necessary, hence a need for public awareness on the dangers of these toxic metals and law for proper disposal of e-waste.展开更多
基金The financially supported by the Program of The National Youth Talent Support Program of China.
文摘In this study,chondroitin sulfate was extracted from Oreochromis niloticus bones(OCS)and isolated to three fractions(OCS-1,OCS-2,and OCS-3).The physicochemical properties and structure characterization including monosaccharide,disaccharide compositions,molecular weight(Mw)of OCS were determined by HPAEC,HPLC-SAX,HPGPC,FT-IR spectra,and 1D/2D NMR.Moreover,their thermal properties,crystalline structure,and microstructure were also analyzed.Results showed that their Mw were between 10 kDa and 50 kDa.CS-6 was the predominant disaccharide unit in four OCS,and the CS-4/CS-6 ratios were close to CS from shark cartilage.Besides,the results of antioxidant activity showed that different fractions of OCS had a distinct DPPH radical,hydroxyl radical,and ABTS+radical scavenging activity.OCS-1 has the highest scavenging activities in DPPH and hydroxyl radical compared with other fractions,which showed a higher medicinal value.Those findings may lay some theoretical basis for the potential application development of OCS.
文摘The optimization of aquaculture production requires the selection of efficient strains. Thus, genetic improvement has become one of the important levers to boost the development of aquaculture. The objective of this study was to carry out genetic characterization of Nile tilapia Oreochromis niloticus, one of the most cultivated fish species in Senegal, in order to select an efficient strain to optimize local fish production. Thus, fish from five different populations (Richard-Toll, ANA, ITACA, Mbodiene and Sauvage) were analyzed, with 15 individuals per population. Genetic diversity and population structure were assessed using molecular genetic analyses by sequence characterized amplified region (SCAR) and microsatellite (SSR) markers. The analyses of the SCARII marker were conducted on four populations (ANA, ITACA, Sauvage and Mbodiene) while microsatellite analyses were conducted on all five populations. The results show high levels of polymorphism of SSR markers, and a high level of observed heterozygosity (Ho), indicating a high within-population genetic variability. These results are in agreement with the AMOVA results, which indicated a high within-population genetic variability (94%). The genetic structure analysis by DAPC indicates that the five populations analyzed are structured into four groups, which are highly heterogeneous because they share common allele individuals. The analysis of the genetic structure by AMOVA showed a low degree of differentiation between the populations (6%), in agreement with the genetic differentiation index (Fst = 0.059). The heterogeneity of studied populations implies a genetic flow over time, which may have existed between the original populations. The overall negative Tajima D values and low genetic differentiation indicate an excess of rare mutations in the populations studied, resulting from a recent population expansion from a limited number of initial breeders isolated in locale hatcheries. Thus, further studies with a much larger panel of markers are required to better differentiate the strains and identify the most efficient ones for sustainable local aquaculture production.
文摘Dried fish are susceptible to bacteria and fungi attack and are liable to chemical changes which cause losses in quality and reduction of shelf-life. It is important therefore to maintain the quality of fish because continuous consumption of contaminated fish and their products may predispose consumers to health hazards. Maintenance of high quality fish therefore calls for adequate and effective preservation techniques. The study examined the effectiveness of essential oils of Ocimum basilicum and Ocimum gratissimum from two Agro-ecological zones of Cameroon in limiting the microbial proliferation and preserving the quality of smoke-dried Oreochromis niloticus fish stored at 25˚C for two months. The plant materials were harvested from the Western Highlands and Monomodal Humid Forest agroecological zones of Cameroon. Extraction of the essential oil from the plants was done by hydro-distillation. The fish species (Oreochromis niloticus) used in this study was chosen based on a survey study on the most consumed species of freshwater smoke-dried fish in the Western Highlands and Monomodal Humid Forest Agro-ecological zones of Cameroon. Heterotrophic bacteria counts, fungi counts and Enterobacteriaceae counts were used to assess the level heterotrophic bacteria, fungi and Enterobacteriaceae respectively in the fish samples during storage and were done by culture techniques using total plate count agar, potato dextrose agar and violet red bile glucose agar respectively. Total volatile basic nitrogen, peroxide value, and thiobarbituric acid reactive substance assays were used as spoilage indices to assess the nutritional quality of the fish during storage. From the survey study, Oreochromis niloticus was the most consumed smoke-dried fish in the Western Highlands (35.45%) and Monomodal Humid Forest (34.55%) agroecological zones. All the EOs caused a significant reduction in the microbial loads, total volatile basic nitrogen, peroxide value, and thiobarbituric acid reactive substance of smoke-dried Oreochromis niloticus as storage progressed. However, the reduction in these values was more pronounced in samples treated with essential oils of O. gratissimum from the Western Highlands, with heterotrophic bacteria, fungi and Enterobacteriaceae counts being 5.89, 6.97 and 4.59 log<sub>10</sub> cfu/g respectively at the end of the storage period. This was followed by essential oils of O. gratissimum from the Monomodal Humid Forest with heterotrophic bacteria, fungi and Enterobacteriaceae counts being 6.11, 7.79 and 4.86 log<sub>10</sub> cfu/g respectively at the end of the storage period. Also, essential oils of O. gratissimum from the Western Highlands was more effective in preserving the fish quality as lowest total volatile basic nitrogen (12.29 mg/100g), peroxide value (2.79 mEq O<sub>2</sub>·Kg<sup>−1</sup>) and thiobabituric reactive substance (1.695 mg MDA/Kg) values were observed for fish samples treated with this extract at the end of the storage period. This was followed by essential oils of O. gratissimum from the Monomodal Humid Forest with total volatile basic nitrogen (14.95 mgN/100g), Peroxide value (3.23 mEq O<sub>2</sub>·Kg<sup>−1</sup>) and thiobabituric reactive substance (2.354 mg MDA/Kg) at the end of the storage period. From the results obtained, essential oils from O. gratissimum were more effective than that from O. basilicum in the two agroecological zones and should be considered as natural alternative to chemical preservatives for further application in food preservation.
文摘This study was carried out in 2022 at the Itato agriculture community estate of fish hatchery in eastern Senegal with the aim of finding an alternative method to 17-α-methyl testosterone (MT) by using Garcinia kola “Bitter kola” powder to obtain Oreochromis niloticus male sex populations. 1800 fry of average size between 0.01 and 0.02 g were distributed in 12 aboveground tanks of 1 m3 each at a rate of 150 individuals/tank, following 6 duplicate treatments. The negative (B1 and B2) and positive (B3 and B4) control diets, to which between 0 and 60 mg/kg of 17alpha-methyl testosterone had been added respectively, were mixed with industrial feed containing 40% protein;the tank diets (B5 and B6), (B7 and B8), (B9 and B10) and (B11 and B12) contained 10 g, 20 g, 30 g and 40 g of Garcinia kola powder respectively for 1 kg of industrial feed con-taining 40% protein. These different treatments resulted in high proportions of males in the order of 97.03%;98.09% for the hormone and proportions of 94.03%;93.26% for 20 g of Garcinia kola extracts. In terms of weight growth, the best average weights for the hormone and Garcinia kola were 0.896 g and 0.980 g respectively. With regard to fish survival, the following results were recorded: 95.53% and 94.56% respectively for additions of 20 g and 30 g of Garcinia kola extracts to the feed supplied to the fish. On the other hand, a significant difference in the mortality rate of 35% and 5% respectively for the conventional hormone and 20 g of Garcinia kola extracts was observed. To conclude the study, it is recommended that further studies be carried out to determine the quality of the flesh, their life stages and the profile of the amino acids present in their proteins.
文摘Irrigation of fish farms with agricultural drainage water may affect cultured fish species. So, the present study utilizes antioxidants supplemented diet to overcome deterioration of drainage water and its negative effect on fish. The studied groups are fish cultured in dechlorinated tap water as control group or drainage water and fed commercial basal diet. While, the other studied groups represented by Oreochromis niloticus fish cultured in drainage water and fed either commercial diet supplemented with vitamin C (5 g/kg diet) or fennel (5 g/kg diet) for 12 weeks. Results of the water physico-chemical parameters of all studied treatments revealed deterioration of the drainage water with a decrease in dissolved oxygen and an increase in pH, total hardness, total alkalinity, salinity, ammonia, nitrite and heavy metals (Cu, Pb and Cd) with significant differences (P ≤ 0.01) in comparison to that of the control dechlorinated tap water group. Data clarified also that Oreochromis niloticus cultured in drainage water showed a decrease in growth rate accompanied by deterioration of fish meat quality. However, fish reared in the same drainage water for the same exposure period and fed vitamin C or fennel supplemented basal diet (5 g/kg diet) recorded values of the studied parameters more or less similar to that of control group fish. Data of the present study, empowered aquaculturist to supplement fish rations with fennel or vitamin C as antioxidants to improve fish growth rate, meat quality as well as protect fish against heavy metals toxicity that could threat Human Being.
文摘The efficacy of Endocrine Disrupting Compounds (EDCs), 17β-estradiol was tested on the fish Oreochromis niloticus in order to understand the intersex relationship of fish, in which sequential hermaphrodism can consist of a male changing into a female (protandry) or a female changing into a male (protogyny). The fish were equally divided into 3 groups. The first group was the control group;the second and third groups were treated with 10 and 100 mg L-1 of 17β-estradiol, respectively, for 30 days. The overall result in this experiment had no significant effect on the growth parameters. Among the two treated groups, the low concentration group shows results similar to those of the control groups. The high concentration group shows changes to the male reproductive system with the appearance of the testis-ova present resulting in an intersex condition of the male gonads. With this experiment, it can be concluded that 17β-estradiol at high concentration reveals positive changes towards the male reproductive system of the fish, Oreochromis niloticus.
文摘Nitrogen (N) and phosphorus (P) wastes produced by Nile tilapia Oreochromis niloticus L. fed Azolla, an aquatic atmospheric nitrogen fixing fern, was evaluated for 90 days in pond experiment. Six isonitrogenous (29.2% crude protein) and isoenergetic (16.9 Kj·g–1) diets A0, A10, A20, A30, A40 and A50, containing 0%, 10%, 20%, 30%, 40% and 50% of Azolla meal (AM) respectively, as partial fishmeal (FM) substitutes, was provided to experimental fish. The Azolla-free diet A0 served as a control. Fish specific growth rate (SGR) was higher with the control diet, the lower values being obtained in A50-fed fish (P Azolla could be used in diet to sustain Nile tilapia growth and as “environmentally-friendly” ingredient to limit P loss, while providing N to the field, beneficially in tropical marshland pond where this nutrient is already limiting.
基金Supported by China Agriculture Research System(CARS-49)Fujian Seed Industry Innovation and Industrialization(2011FJZY)
文摘Through PCR amplification, 5' flanking region and partial open reading frame(ORF) of gene of Nile tilapia(Oreochromis niloticus) was cloned by PCR amplification. Sequence analysis showed that no difference was found in known functional regions. This study was to construct and identify the mammalian expression vector of pEGFP-β-actin and to detect whether it could express in HEK 293T cell line. pEGFP-β-actin was transfected into HEK 293T cells with Lipofectamine 2000. The results showed that correct construction of recombinant pEGFP-β-actin has been shown by restriction enzyme digestion. The expression of gene in HEK 293T cells could be observed under microfluoroscope. pEGFP-β-actin could repress EGFP protein in HEK 293T cells. The results showed that β-actin gene promoter possessed effective transcription activities in eukaryotic cells. The work laid foundations for further study on the gene engineering and autotransgenic tilapia.
文摘The aim of the study was to investigate the antibacterial potential of garlic(Allium sativum),pinus(Pinus elliottii),eucalyptus(Eucalyptus sp.),yerba mate(Ilex paraguariensis)and guava tree(Psidium guajava Linn.)in vitro and the effect of yerba mate supplementation on Oreochromis niloticus physiology and resistance to Aeromonas hydrophila.The in vitro antibacterial potential of the plants was verified by the minimum inhibitory concentration(MIC)method and by the antimicrobial sensitivity test(TSA).The in vivo assay was performed using diet supplementation with yerba mate and challenge with A.hydrophila.After the supplementation and challenge periods biochemical,immune and physiological parameters were evaluated.The in vitro assays showed that only yerba mate presented antibacterial potential against A.hydrophila and no one of the plant extracts were effective against Streptococcus agalactiae.The use of yerba mate in the diet did not influence the immune and metabolic status of O.niloticus.Also,the supplementation did not act as a growth promoter for the fishes.Considering the challenge of O.niloticus with A.hydrophila,the yerba mate did not improve the resistance of the fishes to the bacteria.The yerba mate extract presented potential to be used as an antibacterial agent for fish diseases.Also,more detailed studies are necessary to stablish effective doses and times required for fish treatments.
文摘The approximate general composition and the fatty acid profile of Nile tilapia fed Azolla-diets in ponds were studied for 90 days. Six isonitrogenous (29.2% CP) and isoenergetic (16.9 kJ·g>sup>-1) diets were formulated to contain 0% (A0), 10% (A10), 20% (A>sub>20), 30% (A30), 40% (A40) and 50% (A50) of Azolla meal (AM), as partial fish meal (FM) substitutes. Diet A0 without AM served as a control. Fish growth decreased as AM level exceeded 20% in diets (P 0.05). Crude lipid was significantly lower in fish fed A50 and significant differences were also found in crude ash (P 20, A30 and A50. High level of the fern reduces growth without negatively affecting fatty acid in fish. Fish PUFA, especially the (n - 3) fatty acids, are affected positively, even when fed 50% AM, which is good for the quality of the fish produced in regard to the benefits for the health of consumers.
基金The authors would like to acknowledge NACOSTI(National Council Science Technology&Innovation),for providing research fundsthe Director of KMFRI(Kenya Marine and Fisheries Research Institute)for logistical support,and colleagues from KMFRI technical staff(J.Ouko,R.Mairura,and Z.Awuondo).We also wish to thank the technical staff of UoN(University of Nairobi),Chiromo Laboratories,for instrumental data handling and analysis.
文摘Concentrations of OCP(Organochlorine Pesticide)residues were determined in cultured Nile tilapia(Oreochromis niloticus)fish in target stations within 1st order wetland of River Kuja,Kenya,between February-November,2017.The aim was to assess the residue levels in wild and pond cultured fish within a heavily populated agricultural area of South Western Kenya.Biota samples were analysed for selected HCHs(Hexachlorocyclohexane)isomers,DDT(Dichlorodiphenyltrichloroethane)and metabolites and cyclodienes pesticide residues using GC-ECD(Gas Chromatography Equipped with Electron Capture Detector).Most of OCPs observed were BDL(Below Detection Limit)to detectable levels.Larger percentages(>50%)of DDTs and HCHs were BDL and exhibited consistency,with significant(p<0.05)differences in mean contamination levels in fish within the wetland,with average muscle tissue pesticides concentrate ranging between 0.229-2.541mg/kg for Nile tilapia.Most dominant isomer in target species was Lindane(g-HCH)(3.417±0.983mg/kg)and Endosulfans.Mean Endosulfan sulfate was 2.499±0.071mg/kg d.w.and most frequently detected,and Methoxychlor(2.235±1.459mg/kg),respectively.Mean Aldrin and Dieldrin was 2.028 and 0.574mg/kg d.w.Concentration for DDT and its metabolites was 0.27-3.71mg/kg for p,p’-DDE(DichlorodiphenylDichloroEthene),BDL-1.098 for p,p’-DDD(DichloroDiphenylDichloroEthane),and 0.105-3.518mg/kg for p,p’-DDT with significant differences in mean values and ranges whose levels were below the WHO(World Health Organization)maximum acceptable thresholds of 0.2,2,20 and 5.0mg/kg in fish and sea food.Interventions and monitoring need up-scaling in minimizing public health risks posed by consumption and exposure.
文摘Fishes are suitable for sun drying and smoking. But their high contains of unsaturated fatty acids mak</span><span style="font-family:Verdana;">e</span><span style="font-family:Verdana;"> them very prone to lipid oxidation. However, some plants are rich in natural antioxidants and have been shown to be potent inhibitors of lipid oxidation during processing of meat. The effect of three aqueous plants extracts on lipid stability of </span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">Oreochromis niloticus</span></i><i><span style="font-family:Verdana;"></i></span></i><span style="font-family:Verdana;"> collected in Far-North Cameroon during processing was evaluated. Results show the high nutritious of these fish with high levels of proteins, lipid and ash (71.02</span><span style="font-family:Verdana;">%</span><span style="font-family:Verdana;">, 13.71</span><span style="font-family:Verdana;">%</span><span style="font-family:Verdana;"> and 10.65%, respectively). It has been observed that oleic acid (C18:1), followed by palmitic acid (C16:0) and linoleic acid (C18:2) are the most dominant fatty acids present in </span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">Oreochromis niloticus</span></i><i><span style="font-family:Verdana;"></i></span></i><i><span style="font-family:""> </span></i><span style="font-family:Verdana;">lipids. Their lipid also showed a much higher content of omega-3 polyunsaturated fatty acids (PUFA) compared to omega 6 PUFA. The total phenolic contents (TPC) of the three plants ranged from 12</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;">150 to 16</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;">050 mg/100</span><span style="font-family:""> </span><span style="font-family:Verdana;">g. The leaves of </span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">Moringa oleifera</span></i><i><span style="font-family:Verdana;"></i></span></i><span style="font-family:Verdana;"> exhibited </span><span style="font-family:Verdana;">the </span><span style="font-family:Verdana;">higher content of TPC. The results of iodine, peroxide value and thiobarbituric acids test were revealed that the aqueous extracts of the tree plants had antioxidant properties. These plants extracts inhibit lipid oxidation of </span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">Oreochromis niloticus</span></i><i><span style="font-family:Verdana;"></i></span></i><span style="font-family:Verdana;"> during processing. Increasing of the concentration of plant extracts enhanced their antioxidant activities and the highest oxidation inhibitor was obtained at 30</span><span style="font-family:""> </span><span style="font-family:Verdana;">g/l. </span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">Moringa oleifera</span></i><i><span style="font-family:Verdana;"></i></span></i><span style="font-family:Verdana;"> leaves inhibit highly the lipid oxidation of </span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">Oreochromis niloticus</span></i><i><span style="font-family:Verdana;"></i></span></i><span style="font-family:Verdana;">.
文摘Exposure to heavy metals is an important environmental problem resulting from anthropogenic activities. The aim of this study was the evaluation of some heavy metals as cadmium (Cd), lead (Pb), chromium (Cr) and aluminum (Al), in muscle of fresh water fish Oreochromis niloticus from ten provinces all over Egypt to assess its possible hazards on fish and consumers. The analyzed metals could be detected in all examined samples and their order was Pb > Cr > Cd > Al. A positive correlation between Al concentration and the fish length was observed. The concentrations of Pb, Cd and Cr in fish samples were several times higher than their concentration in water and the bioaccumulation Factor (BAF) ranged from 8.22 - 122.6. The estimated weekly intake of Cd, Pb and Cr for a 70 kg person consuming fish in Egypt (7.94, 15.84 and 9.8 μg) is well below the Provisional Permissible Tolerable Weekly Intake (PTWI) recommended by FAO/WHO. Although heavy metal levels in Egypt exceed the maximum permissible limits recommended by Egypt and WHO in some fish samples, the consumption of Nile O. niloticus from Egypt is safe on human health.
文摘Two 90-day experiments were conducted in the same period in tanks and in earthen ponds to study the effects of culture systems on growth and fatty acid (FA) of Nile tilapia (Oreochromis niloticus L.) fingerlings (mean weight: 16.3 g) fed Azolla, as partial replacement for fish meal (FM). Diets were isonitrogenous (29.2% CP) and isoenergetic (16.9 kJ·g-1) containing 0% (A0), 10% (A10), 20% (A20), 30% (A30), 40% (A40) and 50% (A50) of Azolla meal (AM) respectively. Diet A0, without AM, acted as a control. In both experiments, fish growth decreased as AM level increased in diets (P P 30-A50). Interestingly, those fish were rich in eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3). Consequently, the n-3/n-6 values decreased in tanks, whereas an increasing trend was found in ponds, and values were significantly higher in ponds than in tanks (0.35 - 0.53 vs. 0.08 - 0.17). The results suggest raising Nile tilapia with Azolladiets in ponds to improve growth and produce fish with a better FA composition, for the wellbeing of consumers.
文摘The present study deals with the effect of exogenous treatment of O. niloticus females with L-thyroxine (T4) on the development of the digestive system during larval rearing, and its subsequent effect on larval growth and survival. The development of the digestive tract and accessory glands was investigated histologically and histochemically in the developing O. niloticus larvae, from control and T4-treated spawners. During yolk-sac absorption, the digestive system of the fish underwent further differentiation and the rudimentary alimentary canal became segmented into four different histological regions: the buccopharynx, oesophagus, stomach and intestine. The injection of females O. niloticus with thyroxine (1 or 10 μg T4/g BW) greatly enhanced the development of the digestive tract and accessory glands of larvae as indicated by the quantitative and qualitative changes of the mucus composition from predominantly neutral to a mixture of neutral and acid mucosubstances, or acid mucosubstances occurred during the rearing period for the larvae produced from T4-treated females. This may be due to the direct effect of exogenous thyroxine, which might have been transferred from maternal circulation into the oocytes and larvae, on the synthesis of proteins, which increased with larval development. Thus, thyroxine directly or indirectly improved O. niloticus larval growth, since a marked increase in both, length and weight of larvae occurred during the experimental period. In addition, larvae from treated females also gave a significantly higher survival rate than that of control. It could be concluded that exogenous T4 in maternal circulation might have been transferred into oocytes and larvae. The transferred thyroid hormone appears to play some role in the early development of larvae and may confer a distinct advantage for the growth of the offspring of the Nile tilapia, O. niloticus.
文摘It is estimated that quarter to half a million specimens of the Nile crocodile (Crocodylus niloticus Laurenti, 1768) live in liberty. Ranching crocodiles for their skins has been successfully implemented in several African countries but also in Israel. Recently, in one of these ranches, an increased mortality of crocodile eggs was observed and it was thought that insects were causing their death. Two crocodile eggs were kept together with 100 adults of Tribolium castaneum (Herbst, 1797), while the third egg was kept without beetles. No food for beetles was added to the boxes. The eggs were observed twice a month for any kind of changes on their surface. After two months, at least 39 holes were observed in one egg and 146 on the second egg, which was exposed to beetles, while no holes could be seen in the control egg. Some of the holes were deep enough to see the inner layers of the egg. There is enough evidence to believe that adults of T. castaneum are able to damage the eggs of the Nile crocodile and in some cases lead to their death;measures should be taken to protect the eggs from this and similar species of beetles.
文摘Native polyacrylamide gel electrophoresis have been used to analyze malate dehydrogenase (MDH), acid phosphatase (Acph) and peroxidase (Px) isoenzymes in different tissues (liver, kidney, muscle and heart) of the tilapia fish, Oreo- chromis niloticus in order to study the tissue specificity of these isoenzymes. Three, two and one fractions have been recorded respectively for the three isoenzymes in different studied tissues. The MDH-1 and MDH-2 have been ex- pressed only in muscle and heart while MDH-3 has been expressed in all studied tissues. The percentage amount of MDH in general varied significantly between muscle and different studied tissues. With respect to acid phosphatase, the percentage amount of the total enzyme showed significant difference between liver and muscle and that this variation may be due to higher gene activity in liver. Peroxidase isoenzyme was recorded in liver and heart only with significant increase in liver. The kidney was the least among the studied tissues in showing gene expression for the studied isoenzymes and therefore, liver, heart and muscle tissues are better applicable in studying the isoenzymatic profiles for fish physiology and systematics.
文摘This study was designed to investigate the possible variation in bioaccumulation of heavy metals (lead, cadmium, zinc, cobalt, chromium, nickel, and manganese) in the tissue of harvested Oreochromis niloticus (tilapia) and the associated fungi from vials treated with soil from e-waste dumpsite and soil without e-waste. E-waste is electronic waste which contains valuable metals as well as potential environmental contaminants. The heavy metals in soil and fish samples were determined using flame atomic absorption spectrophotometer (AAS) after homogeneity and digestion of samples. The associated fungi were identified using standard microbiological methods. The genera of the associated fungi were: Penicillium, Candida, Articulospora, Aspergillus, Aspergillus, Aspergillus, Rhizopus, Mucor, Zoopage, Varicosporium and Rhodoturula. The quantity of fungi isolated from each pollution treatments showed that the number of fungi were inversely proportional to the quantity of e-waste soil pollution and directly proportional to the quantity of soil without e-waste pollution. The occurrence of the fungi species revealed that the untreated (control) vial had the highest occurrence (191) while the lowest occurrence (103) occurred in the vial polluted with the highest quantity of soil from e-waste dumpsite. The pH and the biochemical oxygen demand (BOD) of the vials were significantly affected by the pollutions. Variations were also observed in the bioaccumulation of the heavy metals by Oreochromis niloticus. Cadmium (0.01 mg/kg) and nickel (0.02 - 0.08 mg/kg) were the least recorded metal in the tissue of the fish while cobalt was not detected after the five weeks period. The sequence of the heavy metals concentrations in Oreochromis niloticus tissue samples was Zn > Mn > Pb > Cr > Ni > Cd > Co. The accumulation of the metals in the fish tissue were, however, lower than the international maximum guidelines, except for manganese (0.29 - 3.13 mg/kg) that exceeded the 0.01 - 0.05 mg/kg threshold levels for manganese by Federal Environmental Protection Agency (FEPA). Protecting the environments from toxic metals is necessary, hence a need for public awareness on the dangers of these toxic metals and law for proper disposal of e-waste.
