Drosophila melanogaster

1
Drosophila melanogaster

• An investigation into an animal model at Liggins
  Institute

2
First we had to learn about Drosophila...
3

Drosophila melanogasterCommon Fruit Fly
You can tell the sex of Drosophila melanogaster
at the pupa stage by looking closely for the dark
male tarsal sex combs (dark hairs on the
forelegs) through the pupa casing.
Drosophila melanogaster is also known as the
common fruit fly. It has 4 phases to its life
cycle and as an adult it grows to about 3mm
long. Although very small in the animal world,
this insect is very large in the biological
research world. Due to its relatively simple
genetic structure and its short lifecycle, it has
been used as an animal model in science for over
100 years. The average lifespan of a lab
Drosophila is around 26 days for the female and
33 days for the male. Crowded conditions and the
temperature have an effect on the life span of
the Drosophila.

• How can you tell the difference between a male
  and a female fly?
• MALE ADULT
• Male adult flies are smaller
• Black tip on their abdomen
• Rounder abdomen
• Dark tarsal sex combs on its forelegs
• FEMALE ADULT
• Female adult flies are larger
• Abdomen is Pointier
• Abdomen has pattern of even dark bands

24hrs
The adult will become fertile within 12 hours of
hatching from the pupa stage. After mating, the
female lays her eggs on the 3rd day of
fertilisation. She can lay up to 100 eggs a day.
The egg of the Drosophila is about 0.5mm long and
after 24 hours, the embryo is developed and a
larva hatches.
The Life cycle of the Drosophila melanogaster
26-80 days
4 days
The larva continually eats and grows, shedding
its skin at day 1,2 and 4. On its 4th shed, it
will emerge as a pupa.
4 days
References http//www.ceolas.org/fly/intro.html h
ttp//www.yale.edu/ynhti/curriculum/units/1996/5/9
6.05.01.x.html http//www.exploratorium.edu/exhibi
ts/mutant_flies/mutant_flies.html http//www.ncbi.
nlm.nih.gov/books/NBK22079/ http//science.nasa.go
v/science-news/science-at-nasa/2004/03feb_fruitfly
/ http//learn.genetics.utah.edu/
The pupa spends 4 days metamorphosing into a
winged adult.
4
Sexual dimorphism

• Male Female

5
Then we had to learn about genetics...
6
Why do fruit flies look different?Genetic
Mutations
Every organism is made up of many types of cells.
Each cell type has a different role to
play. Inside each cell there is a nucleus which
contains varying sets of chromosomes. These
chromosomes are really efficient at packing up
the long strands of DNA information. The DNA
contains many genes that contain the instructions
for each cell so it knows what to do. Genes carry
the recipes for telling cells what to do. E.g
choosing eye colour, hair or nose shape.
Fruit Flies are different because the mutations
(changes) in each flys genetic code have
altered their colours and shapes. The genetic
instructions for a fruit flys appearance
(phenotype) is in its DNA. The DNA is found in
the nucleus of its cells and it is made up from
bundles of molecules called chromosomes. These
chromosomes are like recipe books that contain
many different recipes. Representing each recipe
are the genes. The genes sit on the chromosomes
and they are responsible for determining specific
phonotypical characteristics or traits. To
build a complete fruit fly, all the genes work
together to select the phenotypes. Short winged,
red eyes, brown body etc. A defect in the gene
may cause the recipe to not have an expected
outcome. Some of these mutations my be beneficial
for an organism while others may be fatal. A
mutation may even create a new species.
What are some of the different phenotypes?
This is a yellow bodied fruit fly This is
a black bodied fruit fly This is an orange
eyed fruit fly
This is a normal fruit fly This is a short
winged fruit fly This is a curly winged
fruit fly

• Inside each cell, the Chromosomes are organised
  into pairs. One of each of the pairs of
  chromosomes have come from the two different
  parents.
• The number of chromosomes that an organism has
  depends on what sort of organism it is.
• Humans have 23 pairs
• Onions have 8 pairs
• Fruit flies have 4 pairs
• Mosquitoes have 3 pairs
• Carp have 52

This is a white eyed fruit fly This is an
eyeless fruit fly This is a leg-headed
fruit fly
References http//www.ceolas.org/fly/intro.html h
ttp//www.yale.edu/ynhti/curriculum/units/1996/5/9
6.05.01.x.html http//www.exploratorium.edu/exhibi
ts/mutant_flies/mutant_flies.html http//www.ncbi.
nlm.nih.gov/books/NBK22079/ http//science.nasa.go
v/science-news/science-at-nasa/2004/03feb_fruitfly
/ http//learn.genetics.utah.edu/
7
What is heredityHow do organisms inherit traits?
Plants and animals inherit traits from their
parents. Every organism gets half its chromosomes
from its father and the other half from its
mother.   Children may inherit brown eyes from
their mother but blond hair from dad.
Fruit Flies are different because the mutations
(changes) in each flys genetic code have
altered their colours and shapes. The genetic
instructions for a fruit flys appearance
(phenotype) is in its DNA. The DNA is found in
the nucleus of its cells and it is made up from
bundles of molecules called chromosomes. These
chromosomes are like recipe books that contain
many different recipes. Representing each recipe
are the genes. The genes sit on the chromosomes
and they are responsible for determining specific
phonotypical characteristics or traits. To
build a complete fruit fly, all the genes work
together to select the phenotypes. Short winged,
red eyes, brown body etc. A defect in the gene
may cause the recipe to not have an expected
outcome. Some of these mutations my be beneficial
for an organism while others may be fatal. A
mutation may even create a new species.
 In 1865 an Austrian Monk, Gregor Mendel
discovered that he was able to predict the traits
of his pea plants because he knew the traits of
the parent plants.   1. Mendel crossed green
seeded plants with yellow seeded plants and got
all yellow seeded plants.   2. Then he crossed
this new generation with each other and he got
some green and some yellow seeded plants.   3.
Mendel had worked out that yellow seed is a
dominant gene and that green seed is a recessive
or weak gene.   4. The green seeded plant can
only be made if both parents carry a green
gene.   The genetic instructions for each trait
is called an allele.   Recessive traits only
show up when both parents are carrying these
alleles. .  
What is a dominant gene?
References http//www.dnaftb.org/4/ http//learn.
genetics.utah.edu/  
Y g Y YY Yg g Yg gg
g g Y Yg Yg Y Yg Yg
8
Here are some of our mutants that werebred from
Otago University - known chromosomes
9
Our investigation into the environmental affects
on an animal model

• Aim To see if diet affected the lifespan of the
  drosophila
• Change the sugar content of the food
• Variable 1 Diet
• high sugar
• low sugar
• control
• Variable 2 Type of mutant
• Yellow white miniature
• Wild type

10
Results

• Low sugar were slower that the other diets to
  breed
• Low sugar produced less offspring
• High sugar displayed bright yellow abdomens
• Single sex vials are not supposed to contain
  larvae
• Wingless variety bred rampantly
• Hs/ls diet had higher death rates at early
  stages.

11
So what is the big idea?

• Both the genotype and the environment affect our
  phenotype

12
Managing Drosophila in the lab...

• Storing the flies providing them a happy home
• (warm for efficient breeding, translucent
  containers for observation)
• Fly nap our saviour
• (3 hours handling time)
• Tipping the Flies
• (maintaining the breeds, dating offspring)
• Making food
• (high sugar, low sugar, organic or not?)

13
Crosses

• Investigating mutant crosses
• Can we predict an outcome?

14
Wild type x Bar
15
5 Wild type x 5 Bar
15/10-1/11/11 17 days

• 200 drosophila offspring counted 100 /100
• Female wild type had a mild eye mutation
• All females were wild type. All males were bar

16
Wild type x Bar
17
Wild type x Yellow white miniature
18
2 Wild type x 3 ywm
15/10-1/11/11 17 days

• 167 drosophila offspring counted 61 /106
• All females were wild type. All males were yellow
  white miniatures

19
Wild type x Yellow white miniature
20
Yellow white miniature x Wild type
21
1 Ywm x 3 Wild type
15/10-1/11/11 17 days 2 counts completed. Ratio
and offspring phenotype confirmed (2 x Headless
anomaly found)

• 199 drosophila offspring counted 89 /110
• All offspring were wild type. 32 Female/male
  ratio

22
Yellow white miniature x Wildtype
23
www.drosophila.moonfruit.com