Transcript Developmental Genetics

miRNA



miRNA ancient form of
regulation.
Protection against viral
pathogens
Quick regulation and
turnover of mRNA.
Drosophila Development: Genetics at work!
Development of Drosophila
Closer look at Early Development of
Drosophila.
Cellularization
Gastrulation and Segmentation
Anterior-Posterior Polarity in Oocyte




Starts during oogenesis
Gurken mRNA
transferred to oocyte.
Signal sent back to oocyte
post Gurken/Torpedo
interaction.
Par-1 mediated
organization of
microtubules to posterior
side of oocyte via Oskar.
Minus end (posterior) and
plus end (anterior).
Dorsal-Ventral Patterning in Oocyte.
Dorsal Gradient
Anterior-Posterior Polarity in Embryo
Syncytial Specification in Drosophila
Anterior-Posterior Polarity in Embryo
Translational Regulation


Stored oocyte mRNAsselective inhibition of
translation.
Genes turned on quickly
post-fertilization.

Relies on the recruitment
of proteins involved in
making a polyA tail.

Drosophila Bicoid gene
product.
Gap Genes


Role in early segmentation
Transcriptional regulators
Pair-rule Genes




Another set of
Transcriptional Regulators.
Develops the precursors
for the actual segments.
Zebra-stripe pattern of
expression.
Stripe position
determined by which
enhancer is bound.
Pair-rule Genes
Segment Polarity Genes


Wingless (Wnt) and
Hedgehog signal pathway
proteins.
Paracrine signaling
maintains segmentation.
Homeotic Selector Genes (Hox)




Regulated by Pair-rule and
Gap genes.
Antennapedia Complex
and bithorax complex.
AbdA and AbdB repressed
by Hunchback and
Kruppel.
Repression maintained by
Polycomb, activation
maintained by Trithorax.
Epigenetic Memory

Trithorax- keeps genes active.




Counteract Polycombs
Modify nucleosomes
Keep H3K4 trimethylated
Polycomb- keeps genes inactivated.


H3K27 methylase
Bind meH3 tails
Hox Genes in Other Species


Mouse Limb developmentdeletion of Hoxd11,
Hoxd12, Hoxd13 causes
polydactyly
Zebra fish, loss of H3K27
demethylase activity and
subsequent Hox gene
disregulation- poor tail
development