MBG 209 TERM PROJECT
a. About Zebrafish
Zebrafish have habitat as Central Asia, Himalayas. It can
be easily produced because of many eggs at once. Thus, allows scientists to make
lots of genetic manipulations. Zebrafish
which is calm and peaceful in nature live
in slow-moving fresh waters. Zebrafish have
lifetime is around 2-3 years, on the 10-12th week of their lifetime they reach
reproductive state. The lifecycle is about 2-3
months long, with 4 major stages: embryo, larvae, juvenile, adult. 1
may live in high populations with low cost and
simple care which makes production easier. Their eggs are convenient for gene expression manipulation. Since their
embryo is transparent early development of them can be observed well.
Zebrafish need to be encouraged to reproduce
with better conditions, they prefer shallow and plant-bearing waters, also
nutritional forms also affect reproductive demands. Additionally, eggs and
larvae forms should be protected by preparing the environment for hiding or
isolating them from adult zebrafish because of the risk of eating. 1
b. About Drosophila
is basically known as fruit fly or vinegar fly and found near fruits. The lifecycle is about 2 weeks long, with 4
major stages: embryo, larvae, pupa, adult. Lifetime is 60-80 days.
Their lifetime may change with temperature or
overcrowding. Since they survive on 12-35oC, basically they can live
everywhere, commonly tropical. Their small size provides scientists to handle
and anesthetize easier. Equipment to maintain a house and carry out any
experiment is inexpensive. Since Drosophila may produce too many eggs and their short
life cycle the experiments are able to be handled with high samples in short
time. Because of every feature are controlled by the only gene and nearly %50 of these genes are homologous to human,
their genetics are easy to be studied and used to understand human genetics and
improve treatment. 2
Drosophila and zebrafish are both modern organisms. They have high reproduction
rate on short time. Their care, follow-up, grow up and replication is easier to handle and there is less concern about ethics. Since their genome is similar to humans and other mammals, research on Drosophila and
zebrafish help to understand and treat human diseases.
procedures – 1
Since the lifecycle of Drosophila may change with
temperature and humidity, the flies stored at 25 oC and %60 humidity.
Unlike its natural food, a mixture of water, yeast and sugar are used as food,
medium, in laboratories generally. To produce mass cultures, trasnparent plastic
or glass bottles/vessels are convenient. The medium is added to these bottles
and with appropriate conditions(temperature, humadity etc.). For mating,
smaller bottles/vessels are used. To examine flies, they have to be fainted.
For this ether vapor are applied to vessels. On white tile with brush, flies
are separated according to the searched features. With microscopes, some flies
are selected to start new cultures. After selection, selected flies are shaken
from vessels/bottles from a freash clean one in incubator for mating, then after
mating, fertilized eggs are tranfered to a beaker or vessels with medium and
larvas are feed by the medium. In the follow-up, larvas turn into pupa form and
then new flies tear out. After 8 hours the new flies become productive. 34
Used equipment is shown below4:
Stereo dissecting microscope is used to inspecting the flies
and separate living, unconscious or dead flies.
Compound microscope has higher magnification rate than stereo
dissecting microscope, is used for examinations of organs, smaller region of
Anesthetizer is a bottle/vessels for putting flies to sleep
with using some ether.
Morgue is a beaker which is used to get rid of unneeded flies,
alcohol or oil may be used. Tapping pad is used for to transfer flies from a
beaker to another one.
White tile is a white, slippery plate to observe flies while
they roam free.
Brush is used to move flies without any damage.
Forceps is used for inspecting and trasnfering individual
flies or larvas.
3. Experimental procedures – 2
a. Steps of Dihybrid Cross
Firstly, virgin females are collected while they
are fainted until they reach productive stage. At this stage, their genotypes were
known. When they are ready to cross, similar number of males and females are
added to vessel with medium and stored in incubator with appropriate
temperature and humidity. After 3-4 days larvaes occurs and parents are transferred.
Within 10 days to 2 weeks new offspring are ready to observation.