Magic and Interactive Storytelling
3. Prototypes
TISSUESOFO.NILOTICUSFINGERLINGSEXPOSED TO SUBLETHAL CONCENTRATIONS OF USED CRANKCASE OIL
Muscle and liver glycogen of the control and treatment of the fish groups were assayed by the Anthrone method as described by Wedemeyer and Yasutake (1977):
3.6.1 Muscle Glycogen
A weight of 100 mg of muscle was boiled in a test tube containing 3.0ml of 30% Potassium hydroxide (KOH) until it dissolved completely in about 20 minutes.
0.5ml of saturated Na2SO4and 3.5ml of 95% Ethanol were added and heated to boiling point in hot water. The set-up was allowed to cool before centrifuging at 600 rpm and the supernatant discarded. The glycogen was dissolved in 2.0ml of distilled water and reprecipitated with 2.5ml of 95% Ethanol. The sample was again centrifuged and the supernatant decanted. The precipitated glycogen was hydrolyzed for 30 minutes in 2.0ml of 5M HCl in a boiling water bath.
The hydrolyzate was cooled and neutralized with 0.5M NaOH, a drop of Phenol red was added as indicator before titration according to the method of Wedemeyer and Yasutake (1977). The neutralized solution for the test was diluted to a known volume of 100ml depending on the expected glycogen content. 5.0ml of the diluted hydrolyzate was transferred into a test tube. A glucose standard of 5.0ml was transferred into another test tube and 5.0ml of distilled water was transferred into a third test tube.
These test tubes were immersed in cold water while 10.0ml of Anthrone reagent was added to each test tube. The test tubes were capped with glass marbles for 10 minutes in boiling water. These were cooled and the absorbance of the samples was read at 620nm wavelength in a colorimeter. The muscle and liver glycogen were calculated in mg/L as follows:
Liver or Muscle glycogen (mg/L) = Au (Cs) As
Where:
Au = Absorbance of Unknown, As = Absorbance of Standard Cs = Concentration of Standard, Wedemeyer and Yasutake (1977).
3.6.2 Liver Glycogen
A weight of 100 mg of liver was boiled in a test tube containing 3.0ml of 30%
Potassium hydroxide (KOH) until it dissolved completely in about 20 minutes. 0.5ml of
saturated Na2SO4and 3.5ml of 95% Ethanol were added and heated to boiling point in hot water. The set-up was allowed to cool before centrifuging at 600 rpm and the supernatant discarded. The glycogen was dissolved in 2.0ml of distilled water and reprecipitated with 2.5ml of 95% Ethanol. The sample was again centrifuged and the supernatant decanted. The precipitated glycogen was hydrolyzed for 30 minutes in 2.0ml of 5M HCl in a boiling water bath.
The hydrolyzate were cooled and neutralized with 0.5M NaOH, a drop of Phenol red was added as indicator before titration according to the method of Wedemeyer and Yasutake (1977). The neutralized solution was diluted to a known volume of 100ml, 5.0ml of the diluted hydrolyzate was transferred into a test tube. A glucose standard of 5.0ml was transferred into another test tube and 5.0ml of distilled water was transferred into a third test tube. These test tubes were immersed in cold while 10.0ml of Anthrone reagent was added to each test tube. The test tubes were capped with glass marbles for 10 minutes in boiling water. These were then cooled and the absorbance of the samples was read at 620nm wavelength in a colorimeter. The liver glycogen was calculated in mg/L as follows:
Liver glycogen (mg/L) = Au (Cs) As
Where:
Au = Absorbance of Unknown, As = Absorbance of Standard Cs = Concentration of Standard, Wedemeyer and Yasutake (1977).
3.7 GROWTH AND FEEDUTILIZATIONOF
O.NILOTICUSFINGERLINGSEXPOSEDTO SUBLETHAL CONCENTRATIONSOF USED CRANKCASE OIL
The growth parameters of the experimental fish were determined using standard methods. The weight and length were measured using a Mettler balance and a
centimeter rule respectively according to the method of Nehemiah et al. (2012) and Mortuza and Misned (2013) to ascertain any increase or decrease in the parameters during the period of the investigation.
3.7.1 Length-Weight Measurements of O. niloticusFingerlings Exposed to the Sublethal Concentrations of Used Crankcase Oil
The total length of the fish groups was measured by placing the fish laterally on a dissecting board and using a centimeter rule to take the measurement. This was done fortnightly and averages were recorded. A total of twenty fingerlings were used in each experimental group for the morphometric measurements. The means were subjected to statistical analysis usingone-way Analysis of Variance ANOVA and correlation coefficient.
3.7.2 Specific Growth Rate (SGR)is a term used in aquaculture to estimate the production of fish after a certain period. It is expressed in weight at harvest−weight at stocking ∕ production period x 100.
SGR was computed as follows:
Where W1 = Initial weight (g) at time t,W2 = Final weight (g) at time T.
Cook, McNiven, Richardson and Sutterlin (2000).
3.7.3 Food Conversion Ratio (FCR) The FCR was calculated as:
USAID (2011).
loge W2 – loge W1
T −t
× 100
3.8 DETERMINATION OF GONADAL