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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