You use the FLP/FRT system to test whether a new Drosophila gene –crunch, that c

Question

You use the FLP/FRT system to test whether a new Drosophila gene –crunch, that causes cells to crunch up – functions in a cell autonomous fashion.The cr gene is expressed in patches of cells in the head (CR-expressing cells).To test for cell autonomy, you generate animals that are: FRT, cr, w/ FRT, cr+, w+. So, What is the genotype of cells that will be informative?If cr acts in a cell autonomous fashion, what will you see? If cr acts in a nonautonomous fashion, what will you see? and If you find nonautonomy, what is one way this could be explained?

Explanation / Answer

FLP/FRT SYSTEM is a system used to genrate site-directed recombinants by targeting this enxyme FLP to specific sites on the DNA(FTR Sites). This allows controlled induction of mitotic recombination when placed under an inducible gene promoter. Strains possessing these can be studies for tissue specific or germline expression.

used here to identify the cell autonomy of any particular gene for example crunch it will allow genotipically mutant and wild type cells to be identified.

If cr is acting in cell- autonomous fashion then the expression will remain confined to only in the patches of cells in the head .

If the expression goes beyond those cells or its expression is present in other cells then it is acting in non-autonomous manner.

The genotype of the F1 is given, but to find whether it is acting in an autonomous manner we require cells which do not possess this crunch gene(cr)/or mutated version of this crunch gene i.e. FTR,cr,w/ FRT, cr,w then against this background when we ectopically express FRT,cr+,w+ in patches of cells in the head then we will be able to distinguish between the cells acting in cell-autonomous and non autonomous fashion.

If cr is acting in an autonomous manner then crunching will happen only in patches of cells expressed in head only.

If cr is acting in a non-autonomous manner then crunching will also occur in other tissues/cells.Crunching can be seen in other parts as well.

If we find non-autonomy then this could be explained by the signalling process. The non-autonomous gene can be acting as a source while the autonomous one will provide receptor for intracellular signaling to take place.

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