Saddleback Journal of Biology - Saddleback College

Fall 2009 Biology 3B Paper
Introduction
The adaptive properties of fish allow them to
metabolize optimally at a certain temperature range.
Tilapia is native to 20-30°, and salmon inhabit areas
that range in temperatures from 0-15°, according Irons
III and Oswood (1991). It is logical that the warm
water adapted fish metabolize better in high
temperature water than a cold adapted fish would. The
body temperature of fish remains close to that of the
water they reside in and their capability to adapt to
marginal thermal change makes fish excellent
ectothermic organisms in which to examine
temperature responses (Guderley, 2004). Since tilapia
has a higher temperature tolerance, its metabolism is
able to function at high temperatures and not bodily
over-heat them; the higher the temperature set point,
the greater the endurance of high-rate aerobic activity
at high ambient temperatures (Heinrich 1977).
When distinguishing a fish as being either
warm or cold water adapted, the fish are labeled by the
temperature ranges that they metabolize optimally at.
Tilapia resides in tropical waters where as salmon
reside in arctic to temperate winter waters and as such
the fish’s internal body temperature have adapted to
account from their habits.
Enzymes act primarily as catalysts, or as
controlling or regulatory elements within an organism.
Enzymes need to be able to fluxuate in order to initiate
changes during strategic positions in metabolism. If
enzymes were non-adaptive, the organism would die
due to its inability to metabolize or regulate itself when
a change in the body system occurs (Hochachka and
Somero, 1984). Succinc Acid is an enzyme that is
required in the Citric Acid Cycle for aerobic
metabolism to occur. By using this enzyme, a
metabolic reaction is triggered within the samples,
which in term allows them to undergo aerobic
metabolic activity after death. As SDH triggers the
intermediate to change from succinate to fumarate
releasing FADH 2 which intern is used for oxygen
reduction. When that oxygen reduction occurs, a
reaction with the methylene blue changes it to its
colorless form showing the metabolic progression of
the sample.
Our objective was to determine if warm water
adaptive fish metabolize better that cold adaptive fish
in an incubator set to 37 o using succinic acid and
methylene blue as indicators of aerobic metabolism. I
hypothesized that the there would be a significant
difference in the rate it took for oxidation-reduction to
change the methylene blue to its colorless form within
the samples.
Materials and Method
Five samples of tilapia and five samples of
salmon were used in this study. The salmon was
obtained from Jon’s Fish market, Dana Point California
on 20, 21, 22 nd of November 2009, and the tilapia was
purchased from Vons, Laguna Niguel California on the
22 nd of November 2009. All measurements were made
on 22 nd of November 2009. The samples were chopped
into pieces and weighted out to ten grams (g). The
samples were then frozen at -80 oC each wrapped in
both plastic and foil individually and labeled. Ten g of
each sample was thawed out to room temperature; each
sample was homogenized together with 25 mL of
sodium phosphate solution individually; The sodium
phosphate (Solution C) is comprised of [306 mL
sodium phosphate monohydrate (Solution A) (NaH 2 Po 4
+H 2 O; 31.73 g to 1000 mL) + 255 mL of Sodium
phosphate Dibasic (Solution B) (NaHPo4 + H2O; 53.6
g to 1000 mL) + 600 mL of Deionized Water (DI)]; the
sodium phosphate solution acts as the buffer for this
experiment. Ten mL of the each homogenized sample
were placed in labeled test tubes and placed back into
the freezer set at -20 oc . the samples were thawed as five
water baths were set to specific temperatures (0 o , 7 o ,
15 o , 22 o , 30 o ). Three drops of methylene blue was
added to each sample followed by .5 mL of succinic
acid (59g/500mL x 10 mL Solution C, a total of 1.18g
of succinic acid was added to 10 mL of Solution C and
heated until dissolved).
A glass rod was used to mix the samples until
the methylene blue fully permeated the samples. The
two test tubes, one of each fish species, were placed in
each of the water bathes. The samples were
continuously checked on at fifteen-minute intervals
until visible signs of oxidation in the samples were
noticed. Then the samples were checked every five
minutes until the half the samples were clear. The
oxidation reduction that is under gone during aerobic
metabolism and how quickly it is being done is what is
being measured when the speed in which it took for
each sample to reduce the entire methylene blue within
sample to its colorless form is recorded. All data was
transferred to MS Excel (Microsoft Corporation,
Redmond, Washington) where all further statistical
manipulations were performed.
Results
The average combined times of warm-water
adapted tilapia in this study was 37.2 ± 5.7 minutes.
The average combined times of cold-water adapted
salmon in this study was 69.8 ± 8.7 minutes. A twotailed
unpaired t-test revealed that the mean combined
times of the two fish were not significantly different
(p=0.165212546).
148
Saddleback Journal of Biology
Spring 2010