Biochemical and Histopathological Effects of Aflatoxin on ...

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1.0 Introduction Aquaculture today contributes substantially to the global fish production on account <strong>of</strong> the all round development during the past decades. A few decades ago, traditional tilapia farming depended mostly on extensive farming methods, where the fish obtained all their nutrition from the aquatic environments in which they were cultured. Nutrient input into the culture systems were limited to fertilizers, <strong>and</strong> agriculture <strong>and</strong> animal products or byproducts. In response to the increased cost <strong>of</strong> l<strong>and</strong> <strong>and</strong> labor, as well as increased dem<strong>and</strong> for fish, nowadays tilapia husb<strong>and</strong>ry requires aquafarmers to stock fish at densities higher than could be supported by the natural productivity. Hence intensive culture <strong>of</strong> tilapia has gained popularity <strong>and</strong> nutritionally complete feeds have become a necessity. The use <strong>of</strong> artificial feeds in aquaculture systems .has increased production <strong>and</strong> pr<strong>of</strong>its considerably (Alceste, 2000). The production <strong>of</strong> aquafeeds has been widely recognized as one <strong>of</strong> the fastest exp<strong>and</strong>ing aquaculture industries in the world with annual growth rates in excess <strong>of</strong> 30% per year. It has been estimated (Tacon, 1997) that the total world production <strong>of</strong> manufactured compound animal feeds was about 560 million metric tonnes in 1995 <strong>of</strong> which aquatic feeds constituted 3% or 16.8 million metric tonnes. An estimated 60% <strong>of</strong> the total world aquafeed production was manufactured in Asia <strong>and</strong> Europe with a fourth produced for carp, tilapia, milkfish <strong>and</strong> other fish species feeding low on the food chain. In tropical countries like India where aquaculture is still developing, it IS common to observe pelleted feeds that are being produced with inappropriate procedures for bagging, transport <strong>and</strong> storage. These facts, in conjunction with the high levels <strong>of</strong> temperature <strong>and</strong> humidity in these areas 1
are probably the causes for the presence <strong>of</strong> fungal growth <strong>and</strong> the potential for aflatoxin production. <strong>Aflatoxin</strong>s are a family <strong>of</strong> closely related heterocyclic compounds produced by some strains <strong>of</strong> the fungi, Aspergillus flavus <strong>and</strong> Aspergillus parasiticus. The important feed ingredients like soybean meal, rice bran, groundnut oil cake <strong>and</strong> mustard oil cake at present considered as very valuable items in fish feeds may be contaminated by aflatoxins. During harvest <strong>and</strong> post harvest operations, the grain <strong>and</strong> oil seeds may not get dried up properly <strong>and</strong> these contain high undesirable amount <strong>of</strong> moisture, which makes them good media for the growth <strong>of</strong> moulds. <strong>Aflatoxin</strong> is a potent liver toxin <strong>and</strong> carcinogen, with aflatoxin B1 being the most toxic compound (Ngethe et al, 1992) responsible for the major toxicity syndrome "aflatoxicosis". Aquatic vertebrates <strong>of</strong> widely divergent taxa are known to suffer toxic effects <strong>of</strong> dietary aflatoxin. For example, dietary levels <strong>of</strong> AFB1 at or below 25 ppb adversely affected the productive performance <strong>of</strong> ducklings (Ostrowski - Meissner, 1982 a,b); teleosts are also susceptible to AFB 1 toxicity. Rainbow trout has one <strong>of</strong> the highest sensitivities to aflatoxin <strong>of</strong> all animals. In this species, an intake <strong>of</strong> less than Iug AFB1 per kg diet can cause liver tumors, <strong>and</strong> the LDso for aflatoxin in fish weighing 50g is 0.5 1.0 mg/kg <strong>of</strong> diet (LoveIl, 1989). Warm water fishes are generally less sensitive to aflatoxin than cold-water species. Pathological responses to aflatoxin have been reported for channel catfish (Smith, 1982) <strong>and</strong> tilapia, Sarotherodon spiluris (HaIler <strong>and</strong> Roberts, 1980). The increasing awareness <strong>of</strong> the scale <strong>of</strong> aquatic environmental problems has focused attention on the urgent need for sensitive <strong>and</strong> precise diagnostic tools or biomarkers with a predictive capability for the assessment <strong>of</strong> toxic contaminant impact. Detection for changes in the amounts <strong>and</strong>/or 2
Page 1: BIOCHEMICAL AND HISTOPATHOLOGICAL E
Page 6 and 7: CHAPTER 1 Introduction CHAPTER2 Rev
Page 8 and 9: Estimation ofAST E
Page 12 and 13: distribution of ma
Page 14 and 15: C H A P T E R Review of</st
Page 16 and 17: 2.3 Structures of
Page 18: animals. As is the case with other
Page 21 and 22: When the dose was increased ten fol
Page 23 and 24: neoplastic cells and</stron
Page 25 and 26: 2.10 b. Carbohydrate and</s
Page 27 and 28: Any discussion in multistage carcin
Page 29 and 30: 3.0 Introduction Fungi grow on pell
Page 31 and 32: imperative to use a method which is
Page 33: MgS04.7H20 FeS0 4.7H20 Distilled wa
Page 36 and 37: 3.3.6 Preparation of</stron
Page 38 and 39: Aflatoxin biosynth
Page 40 and 41: The solubility of
Page 42 and 43: 4.0 Introduction Chemical compounds
Page 44 and 45: Generalized Scheme for Oxidative In
Page 46 and 47: Initiation and pro
Page 49 and 50: (d) Glutathione peroxidase (E.C.l.l
Page 51 and 52: 4.9.l.b Estimation of</stro
Page 53 and 54: Preparation of Tis
Page 55: Procedure Tissues homogenates were
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was 0.559. Concentration 0.375 ppm
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(Madhusudhanan et al, 2000). But in
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5.0. Introduction Structural <stron
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PLATE 8.5 Section of</stron
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The GlIb section of</strong
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All experimental fish appeared norm
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lesion, serving as precursors <stro
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C H A P T E R 6 Aflatoxin</
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Biochemically, afl
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}.2 Materials and
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incubation, 0.2ml of</stron
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times. Waited for 10 minutes till a
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2. Buffer: Sodium carbonate- bicarb
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added to O.Sml of
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Procedure 2g of fl
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diluent solution. Using a commercia
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Parameter Treatment Urea ( J1 moles
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4 3 .... Cl 2 1 o Control 0.375ppm
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300 250 200 "Cm150 E 100 50 o Contr
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Treatment Parameter P value Cholest
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I Source of Variat
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113 type seem to take an active rol
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C H A P T E R 7 Electrophoretic Ana
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116 Among the many biornarkers the
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118 refrigerator for some time to e
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7.1.2b Reagents for electrophoresis
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7.1.2c Preparation of</stro
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3) 10% SDS 4) 6 M Sodium chloride 5
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) Serum Protein (Non SDS Page) 129
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fragments of simil
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C H A P T E R 8 Effect of</
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may result from destabilization <st
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2) Buffer: Citrate buffer (O.05M) <
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Source of Variatio
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Groups Pvalue Control vs 0.375ppm N
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8.1 Studies on the Erythrocyte Memb
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4) To O.lml of the
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8.ID Discussion The results obtaine
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a) Preparation of
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Source of Variatio
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8.3 Studies On Muscle Retention 8.3
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Detection: Waters 440 Absorbance at
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8.3C Results The results are presen
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9.0 Summary The present study was u
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• Aflatoxin resi
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BIBLIOGRAPHY Abedi A Hand</
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Bruenger, A and Gr
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Egmond H P V and W
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Hendricks J D, Wales J H, Sinnhuber
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Lowry 0 H, Rosenbrough N J, Farr A
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New M B (1987). Feed and</s
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Saber N A (1995). Depression <stron
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Soni KB, Rajan A and</stron
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Verma R J, Kolhe A Sand</st
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