Human Drosophila C. elegans ~ 24,000 Genes ~ 13,000 Genes ~ 19,000 Genes Mouse ~ 24,000 Genes
Somatic Cell Nuclear Transfer Cloning
Transcription Initiation
Gene Regulatory Proteins and the DNA Sequences That They Recognize
Asymmetric Localization of Ash1 Transcription Factor DICDAPIAsh1-GFPAsh1 mRNA “Mother cell” “Daughter cell”
Developmental Fate
Caenorhabditis elegans 959 Somatic cells Germ cells
C. elegans Life Cycle
Cleavage Divisions Egg DAPI stained embryo
Asymmetric Segregation of “P Granules” Egg Immunostaining of P Ganules
Wild Type par-1 Mutant Par (Partition) Mutants DIC P granules
2-cell embryo Plasma Membrane Cytosol
Early L3
Late L3
Early L3 Fate Map
“Vulva-less Phentoype “Bag of worms” “Bag of embryos”
EGF Pathways of Vertebrates
“Notch” Receptor
2 o VPC 1 o VPC (Lin-12)
Two-Signal Model of Vulva Development
T.ap Cell Development
LIN-14 Mutations
Lin-14-GFP WT Worms L1 Adult L3 L2
lin-4(gf) lin-4(lf) LIN-4 Mutations
RNAi (RNA Interference) Lin-4 RNA Lin-4 RISC Lin-14 mRNA RISC = RNA-Induced Silencing Complex miRNA = micro RNA
Micro RNAs Humans ~ 220 miRNAs ~ 2000 “Target” mRNAs C. elegans ~ 88 miRNAs ~ 30 miRNAs expressed during larval development
Drosophila melanogaster
Anterior Posterior Dorsal Ventral
Cleavage in the Drosophila Embryo
A P A P Larva Embryo
2 hrs. 10 hrs. A P A P
A P A P
Genetic Hierarchy in A-P Axis Specification
Mutant Phenotypes for Maternal-Effect Genes
Bicoid mRNA/Protein Distribution
Gap Gene Expression Patterns
Bicoid Controls Hunchback (hb) Expression