6. Plane Polarity Flashcards
planar polarity
specific tissue polarity involving coordinate asymmetrical distribution of cells and subcellular structures within the plane of a single cell layer
tissue polarity
coordinate asymmetrical and ordered distribution of cells and subcellular structures within a tissue
organ polarity
asymmetrical and ordered distribution of cell and tissue
layers along an axis of an organ
What can be used as a genetic system to study cell polarity and differentiation
Root hair
Two closely related grasses Phleum spec. and Sporobolus spec. show differences in the polar placement of root hairs – suggesting a genetic basis of this trait.
How looks the polarity in animals like?
Uniform polarity of single cells or multicellular units within the plane of a tissue layer. proximal and distal
Planar Cell Polarity in Drosophila: Wing hairs are oriented towards a distal wingless ligand gradient at the edge of the wing
Planar Cell Polarity in the Drosophila Wing requires Wingless and Wnt4 activity
in plants: planar polarity we got
basal and appical
HOw does mulitcellulary occure?
Note: During evolution multicellularity arose independently in the animal and plant kingdom (convergent evolution). The last common ancestor was
most likely unicellular.
Who does the job for patterning and polarity in animals and who in plants?
Plants: Auxin
Animals: wng (wingless), antalogon: wind
Planar Cell Polarity in Drosophila wing requires…
Wingless and wnt4 activiy; a double mutante would die.; polarity in roots (roothair) and in animals (hairs on the wing)
Where ist ROP (Roh-of-Plants) orientated?
accumulation: early polarity marker where the cell will go out. ROP2 where the root hair goes out
Planar polarity means
… tissue polarity
The position of root hair initiation is directed towards…
Plus: what needs polaare orientation?
the cencentration maximum of an auxin gradient in the root tip
polare Orientierung der Wurzelhaarauwüchse benötigt den Auxin Transporter “auxin influx carrier 1” (aux1); efflux is regulated with PIN2 just at the upper side of the cell
knock out aux1 and plant will get problems with the polarity.
Which 2 genes act synergistically? What does that mean?
Aux1 and EIN2 (Ethylene insensitive2)
What means synergistically?
same pathway or same target; stonger phenotype than additive
Synergie entsteht, wenn der Beitrag zweier Mutationen zum Phänotyp einer Doppelmutante die Erwartungen an die additiven Effekte der einzelnen Mutationen übertrifft. Die molekulare Charakterisierung von Genen, die an synergistischen Wechselwirkungen beteiligt sind, hat gezeigt, dass Synergien hauptsächlich durch Mutationen in funktional verwandten Genen entstehen. Jüngste Forschungen an Arabidopsis thaliana haben unser Verständnis der sich daraus ergebenden insynergistischen Szenarien erweitert Phänotypen. Diejenigen, an denen homologe Loci beteiligt sind, resultieren gewöhnlich aus verschiedenen Ebenen der funktionalen Redundanz. Einige dieser Loci ergänzen sich nicht oder werden in bestimmten Mehrfachmutantenkombinationen dosisabhängig, was darauf hindeutet, dass die Auswirkungen von Haploinsuffizienz und Redundanz kombiniert werden können. Synergien, an denen nicht homologe Gene beteiligt sind, spiegeln wahrscheinlich die Topologie der regulatorischen oder metabolischen Netzwerke wider und können auftreten, wenn an einem Knoten konvergierende Pfade unterbrochen werden.
Which gene has also an impact of root hair polarity?
Partial Loss-of-Function Alleles or Allele Combinations Reveal the Contribution of the GNOM Gene to Planar Polarity; tested with gne/gnb=gneb mutant
Function reduction: hairs are shorter and sometimes fare or close
A Local Auxin Source Can Instruct Planar Polarity
