L6 - Intro to Drosophila Flashcards
Advantages of mouse
Good genetics
Well established
Advantages of chick
Accessible embryos
Low cost
Advantages of zebrafish
Accessible embryos
Reasonable cost
Advantages of drosophila
Accessible embryos and adult stages
Very low cost
Excellent genetics
Not ethical conserns
Disadvantages of mouse
Expensive Slow (long generation time) Home office/ethical restrictions
Disadvatages of chick
No genetics
Home office/ethical restrictions
Disadvantages of zebrafish
Genetics are problematic
Home office/ehtical considerations
Disadvabtages of drosophila
Not a vert
Kept as live stocks
At 25 deg how long is drosophila life cycle
10 days
At 18 deg how long is drosophila lifecycle
21 days
What occurs in first 3 hours of drosophila lifecycle
Go from fertilised egg to a segemented embryo with 3 germ layers
How many larval stages
3
What do the larvae do
Essentailly eating machines to build up fat (energy used during metamorphisis)
Why do larval have 3 stages
Get too big for their skin so the only option is the shead it
Describe what happens in the pupal stages
Crawls up the side of the vial and the skin hardens
Describe what happens during metamorphisis
Larval tissue dissovlves and adult body shell forms
Fat accumulated during instar stages used to provide energy for this process
Lifespan of drosophila
Average around 60 days
What did morgan discover in 1910
The white eyed fly
What was constructed in 1913 by Stutevant
Constructed the first genetic map with genes being arrnaged in a linear order
In 1927 what did muller show
That X rays causes mutations and chromosomal mutations
What occured in 1979/1980 performed by volhar and wischaus
Saturation mutagenesis to identify genes involved in patterning and development
Example of technqiue for trangenics
P-element transformation
What occured in March 2000
The drosophila geneome was sequenced
How many Chr in drosophila
How many Chr arms
5 Chr
7 arms
What are the 7 drosophila Chr arms
X 2L 2R 3L 3R 4 Y
How many bases on the 7 chromsome arms
137.6 Mbps
The remaining gaps of around 1.5 mbps are found where …
In heterochromatin regions
Around how many genes in drosophila
17600
Ptp61F is a
tyrosine phsophatase
When allignement of ptp61F is performed what aras appear to be conserved
Exons
Regulatory sequences
1 male and 1 female drosophila can give rise to
Upwards of 200 offspring
What does drosophila courtship include
Orientation Tapping Wing vibration Licking Attempted copulation
What different sensory modalities does drosophila courtship include
Audiotion - olfaction - taste - vision
How was it shown drosophila courtship was genetic
Two dros grown in isolation and in dark
When reintroduced they still perform the courtships acts
What is found at the very tip of the testes
Hub cells
What is maintained immediatly adjacent to the hub cells
A stem cell population
What occurs when stem cell in the testes divides
One closest to the hub cell maintains stem cell fate
Other cell divides and can give rise to upward of 60 spermatids
What do hub cells secrete
What is this involved in
Upaired (ligand)
Invovled in the JAK/STAT pathway
What is attached to each ovary
Strings of ovarioles
Where is sperm stored in the feamle
Seminal receptacel
Where is the egg laid
Drilled into the foot where it is laid
To form the oocyte how many divisions may occur
4 incomplete cytoblast mitotic divisions
What occurss in the nurse cells
Endo-reduplication - many copies of the genome contained here
What do the nurse cells produce
Maternal factors for the devleoping oocyte
Give as example of a maternal contribution
Oskar mRNA
Describe the process of relocalising maternal contributions form the nurse cells to the oocyte
Cytoplasmic dumping occurs via ring canals
What can occur after cytoplasmic dumping via ring canals
Some of the genes and gene products can be actively localised to regions of the egg
What must occur in order for activation of the egg
Fusion of the male and female pronuclei
Describe polytene chromsomes
Giant chromsomes which occur when the DNA is duplicated by not separated
What occurs when a polytene chromosome is stained for pol2
Bands show little gene activiy
Interbands show an active gene
Puffs show and extremly active gene
Describe the localisation of bicoid and oskar mRNA
Bicoid - anterior of the cell
Oskar - posterior
How is cytoplasmic localisation of maternal contributions achieved
Through transport by the cytoskeleton
(Microtubules, plus and minus ended motors, glue then anchors them into postion
What is the chorion
The egg cell - secreted by follicle cells
What is the vitelline membrane
A hydrophobic coating which prevents the egg from drying out
Egg development occurs via a series of
Of which there are ___ stages
Nuclear division
14
During early development in drosophila there is no
External gene expression
During drosophila early development where do most of the nuclei end up
End up on the outside of the egg
What occurs in drosophila after the 14th division
Membranes go up from the outside and each nucelus pinches off into its own cell
Describe the drosophila larva
Segmented into a denticle belt
What occurs in a Stat92e (-/-)
There are gaps where some of the segemetns should be
