Lecture 1 - GAL4/UAS System Flashcards
Resting potential and threshold potential of nervous system
- 70 mV = resting potential.
- 55 mV = treshold potential.
Explain synapses. Use gap junctions, neurotransmitters, calcium influx, etc.
Synapses can be electrical (gap junctions) but are usually chemical. The chemical nature is a release of neurotransmitters, which are stored in vesicles.
Influx of calcium triggers pre-synaptic vesicles to fuse with membrane, so that neurotransmitters can be released into the gap.
Describe the term ‘behaviour’ according to Ridley (1995).
Behaviour is any orderly movement with recognisable and repeatable patterns produced by members of species. (e.g. courtship, predation, migration, etc.)
Behaviours are polygenetic traits. What does that mean?
Many genetic loci interact in complicated ways to influence the development and function of neural circuits. Ultimately, neural circuits direct behaviour.
Vertebrates and invertebrates share the same basic plan of a CNS and PNS.
Name a couple differences between nervous systems in invertebrates and vertebrates.
- Vertebrate brains have more neurons devoted to information processing.
Invertebrates have fewer but larger and more complicated neurons. - Mammalian neuronal axons have myelin sheaths and invertebrates have no myelin, “just” some giant axons to convey messages quickly.
- Vertebrates are encased in a bony skull and spinal column and invertebrates CNS are often built around the digestive tract.
Manipulation of gene expression:
Forward genetics use random mutagenesis and observe effects on phenotype and THEN identify mutation/gene responsible for altered phenotype.
What happens in reverse genetics?
Reverse genetics alter specific genes and then the effect of the altered gene on phenotype is determined.
Why are flies often used for neurobiological research?
Flies are easy to grow, cheap, have a short life cycle and display all the characteristics of a multicellular organism (including complex organ structure and complex behaviours).
GAL4/UAS System is used to overexpose or knock down a particular gene in a tissue specific matter.
How does GAL4 work?
GAL4 is a transcription factor from yeast and drives gene expression on any gene that has UAS sequence.
Why is GAL4 a handy tool in neurobiological experiments?
GAL4 won’t drive expression on any other part of DNA that does not have the UAS sequence (which you can put there).
How can you create transgenic flies using the GAL4/UAS system?
When you cross flies who have GAL4 or UAS expression, their offspring will have GAL4 and UAS expression, which means that genes containing UAS will be expressed –> Transgenic flies.
GAL4 driver lines:
GAL4 is controlled by a promotor, which can be minimal (enhancer trap) or characterised. What’s the difference?
Minimal (enhancer trap) - GAL4 is expressed in the pattern of any enhancers that are nearby. Enhancer traps tend to drive expression in large groups of neurons.
Characterized - specific endogenous gene and GAL4 is expressed in the same pattern as the endogenous gene.
Why are worms like C elegans used in neurobiological research?
Worms are easy to grow and display all the characteristics of a multicellular organism, including a complex organ structure and behaviours.
Why are mice like M musculus used in neurobiological research?
What are disadvantages?
Vertebrate model: They are more closely related to humans in terms of genome, physiology and anatomy. Disadvantages: a lot of ethical issues much more complex nervous system longer life cycle much more expensive
