Human

DrosophilaC. 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 SequencesThat They Recognize

Asymmetric Localization of Ash1 Transcription Factor

DIC DAPI Ash1-GFP Ash1 mRNA

“Mother cell”

“Daughter cell”

Developmental Fate

Caenorhabditis elegans

959 Somatic cells1000-2000 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

Early L3

Late L3

Early L3 Fate Map

“Vulva-less Phentoype

“Bag of worms”

“Bag of embryos”

EGF Pathways of Vertebrates

“Notch” Receptor

2o VPC

1o 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

GeneticHierarchy inA-P AxisSpecification

Mutant Phenotypes for Maternal-Effect Genes

Bicoid mRNA/Protein Distribution

Gap GeneExpressionPatterns

Bicoid Controls Hunchback (hb) Expression