Development system 5-2-2016

Type of questions developmental biology seeks to answer How do cells arising from a fertilized egg become different from one another?(differentiation) How do cells become organized into complex structures such as limbs? (patterning and morphogenesis) What controls the behavior of individual cells such that these highly organized patterns emerge? How are the organizing principles of development embedded within the egg, and within the DNA? How have changes in developmental program and in gene expression, led to the evolution of the great diversity of animal forms? (EVO-DEVO)

Gene regulatory networks for development PNAS 102: 4936–4942; 2005

Are all embryos looks similar?

Historical origin of developmental biology

A Hierarchy of Inductive Interactions Subdivides the Vertebrate Embryo

Hox Genes Permanently Pattern the A-P Axis What is the regulatory role of Ubx in development?

The Developmental Potential of Cells Becomes Progressively Restricted

Regulatory DNA Seems Largely Responsible for the Differences Between Animal Species

Through Combinatorial Control and Cell Memory, Simple Signals Can Generate Complex Patterns

Two different types of development program British vs American

Small Numbers of Conserved Cell–Cell Signaling Pathways Coordinate Spatial Patterning

Morphogens Are Long-Range Inductive Signals That Exert Graded Effects

Morphogens Are Long-Range Inductive Signals That Exert Graded Effects Production (pulse or steady state), diffusion (fast or slow) and degradation (half life( determine the range and steepness of its resulting gradient

Lateral Inhibition Can Generate Patterns of Different Cell Types

Short-Range Activation and Long-Range Inhibition Can Generate Complex Cellular Patterns

Asymmetric Cell Division Can Also Generate Diversity

Initial Patterns Are Established in Small Fields of Cells and Refined by Sequential Induction as the Embryo Grows

Different Animals Use Different Mechanisms to Establish Their Primary Axes of Polarization

Studies in Drosophila Have Revealed the Genetic Control Mechanisms Underlying Development

Egg-Polarity Genes Encode Macromolecules Deposited in the Egg to Organize the Axes of the Early Drosophila Embryo

Egg-Polarity Genes Encode Macromolecules Deposited in the Egg to Organize the Axes of the Early Drosophila Embryo

Three Groups of Genes Control Drosophila Segmentation Along the A-P Axis

Three Groups of Genes Control Drosophila Segmentation Along the A-P Axis

A Hierarchy of Gene Regulatory Interactions Subdivides the Drosophila Embryo

A Hierarchy of Gene Regulatory Interactions Subdivides the Drosophila Embryo

Egg-Polarity, Gap, and Pair-Rule Genes Create a Transient Pattern That Is Remembered by Segment-Polarity and Hox Genes

A Competition Between Secreted Signaling Proteins Patterns the Vertebrate Embryo

Hox Genes Control the Vertebrate A-P Axis

Hox Genes Are Expressed According to Their Order in the Hox Complex

Hox Genes Control the Vertebrate A-P Axis

Notch-Mediated Lateral Inhibition Refines Cellular Spacing Patterns

Asymmetric Cell Divisions Make Sister Cells Different

A Gene-Expression Oscillator Acts as a Clock to Control Vertebrate Segmentation

A Gene-Expression Oscillator Acts as a Clock to Control Vertebrate Segmentation

Intracellular Developmental Programs Can Help Determine the Time-Course of a Cell’s Development

Repulsive Interactions Help Maintain Tissue Boundaries

Groups of Similar Cells Can Perform Dramatic Collective Rearrangements

An Epithelium Can Bend During Development to Form a Tube or Vesicle

An Epithelium Can Bend During Development to Form a Tube or Vesicle

Developmental bias in cleavage-stage mouse blastomeres. Curr. Biol. 23, 21–31; 2013.

Two appendages of the fly, the haltere and the wing, grow to very different sizes. Limited expression and mobility of a growth morphogen is partly responsible for this difference. Science 313: 50-1; 2006

The Wingless protein (Wg) is thought to regulate the development of Drosophila wings by diffusing from Wg-secreting cells, thereby activating Wg target genes in distant cells as the wing grows. Nature 505: 163-4; 2014.

How to screen development mutants in fly or fish