C. elegans Programmed cell death Flashcards
What does it mean that the fate of the cells in C. elegans is predetermined?
131 cells reproducibly die during devleopment
What is cell death used for in development in general?
sculpting (fingers, hollow stem plants)
deleting structures (formation of veins and capillary)
adjusting cell numbers (neurons)
removing dangerous or injured cells
How do you recognize cells that underwent apoptosis in C. elegans?
see cell corpses
don’t have macrophages, so cells get engulfed by their neighbors
What happens during apoptosis and which types are there?
cells undergo nuclear and cytoplasmic condensation
the cells is broken up into membrane-bound fragments called apoptotic bodies
apoptotic bodies are shed from epithelial-lined surfacec and taken up by other cells
upon endocytosis, fusion with phagosomes
type I: apoptotic
type II: autophagic
Which genes specify NSM sister neurons for PCD?
ces-1
ces-2
stands for CEll death Specification
Which genes are required for killing of cells that are supposed to undergo PCD?
egl-1 inhibits ced-9
ced-9 cannot inhibit ced-4
ced-4 can for a structure resemblin apoptosome and activate ced-3
Which gene blocks cell death?
ced-9
Which gene is required for engulfment of the cells?
ced-1
CEll death Defective
first one discovered because mutant not forming cell corpses
How do you order genes in a cascade?
How do you determine if they are up- or downstream of eachother?
by epistasis analysis (double mutants):
phenotype because of mutation of A masks the phenotype of mutation of B
if talking about killing: only 2 states (death or no death)
epistatic = downstream
if talking about a sequence of events with one event being dependent on completion of the event prior to that:
epistatic = upstream
Which two analyses can be used to order genes in a hierarchic order?
epistasis
overexpression
