Lecture 6 Introduction to drosophila
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What did Bridges show in 1914/1916
That chromosomes must contain genes
Until 1927 what were scientists interested in?
They were all interested in hereditary which is the genetic transmission of characteristics from parent to offspring.
What was shown in 1980s/90s
A range of techniques that use transgenic animals to either visualise, misexpress or reduce gene expression
What did enhancer traps show
promotor trapping
What did Gal/UAS show
gene misexpression
What did FLP/FRT show
‘clonal’ mutant analysis
What did RNAi show
ex vivo and in vivo
What did ‘omic’ technologies show
genome, transcriptome, proteome etc.
How long is the Drosophila genome
143, 726, 002 bp in length
What did aligning the genome of different drosophila show
shows protein coding exons/ regulatory proteins e.g. enhancers/TF are well conserved in different species because they are encoding proteins. They are of high significance and there are only a limited number of ways to code for a certain protein if you want it to continue to function. Introns are not conserved as they do not encode proteins.
How do females and males mate i.e. monogamy etc
• Females ‘play the field’ to find the most suitable partner to mate with • Males want monogamy so that the female produces your offspring • Therefore, males have sex peptides that adhere to the tail of the sperm, makes the female non-receptive to the courtship behaviour of other males • Females have anti-peptides to stop this interaction • This is why you end up with long sperm tails e.g. Drosophila bifurca (50mm)
How many eggs are made at once
Many
How many times do females need to mate
Once
Define stem cell maintenance in females
Stem cells are right at the tip with surrounding cells that remain as stem cells and cells further away differentiating into eggs
Describe puffs in polytene chromosomes
• Puffs an extremely active gene - Polymerase II (green stain) makes RNA for protein coding genes shows this is usually in areas of the genome which are puffed up/biggest as gene transcription is happening here
How many bands are in polytene chromosomes and what is there kB
• Approx. 5000 bands, each approx. 22 kb
What do nurse cells produce
Maternal factors for the developing oocyte • Proteins and RNAs made in nurse cells • Transferred into developing oocyte • Allow progeny to develop quickly
What stages are there in egg development
• There is no G phase/cell division (only S and M) to allow rapid division of the nuclei.
Describe segments of a drosophila
T1-T3, A1-A8
At 2 hours what is the drosophila called
Syncytial blastoderm
3 hours what is drosophila called
Cellular blastoderm
Name common IC signals used in drosophila
HH - Ptc (receptor) for patterning of insect segments and positional signalling in insect leg and wing discs Wng - Frizzed R - for segment/imaginal disc segmentation Delta/serrate - Notch R - for oocyte polarity TGF alpha - EGF R - polarisation of oocyte Dpp (TGFbeta) - for DV patterning and patterning of imaginal discs FGF - FGF R - migration of tracheal cells