mirna mirna ancient form of regulation. protection against viral pathogens quick regulation and...
TRANSCRIPT
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 mRNAs-
selective 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
development-deletion of Hoxd11, Hoxd12, Hoxd13 causes polydactyly
Zebra fish, loss of H3K27 demethylase activity and subsequent Hox gene disregulation- poor tail development