MCB 141

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MCB 141 Developmental Biology
Lecture 2 Jan. 22, 2009
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Development single cell becomes many
different types of cells
But cells also need to be in the correct
position
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I. Example of asymmetric division tunicate
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Example of asymmetric division tunicate
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Edward Conklin (1863-1952) Styela picta
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Better image - Fig. 8.36 of the textbook
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How would you test the importance of the yellow
cytoplasm?
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Acetylcholinesterase in ectopic (new) location
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Macho-1 mRNA
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II. Example of induction
C. Elegans vulval development
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Anchor cell
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Ablate the anchor cell
Anchor cell
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Anchor cell sends signal (EGF) P3-8 have the
receptor (EGF-R) Why does only P6 become the
actual vulval opening?
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The more EGF signal a cell gets, the more
inhibitor it produces. Ensures that only one cell
will form vulval opening. This is an example of
III. Direct interaction
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Another example of III Direct Signaling (local
interaction)
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Another example of III Direct Signaling (local
interaction)
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Development single cell becomes many
different types of cells
But cells also need to be in the correct
position
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What makes one cell different from
another? Differential biochemical
activity differential gene activity differenti
al protein activity
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All cells contain the same complement of
genes? How do we know this?
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One exception B-cells that make antibodies
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Problem to discuss in section What would
happen if you cloned an animal from the nucleus
of a mature B-cell?
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mRNA
protein
The regulatory regions make sure that different
proteins are expressed in different cells.
For example, hemoglobin in red blood cells and
myosin in muscle.
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coding region
brain enhancer
digit enhancer
spine enhancer
A particular gene may be expressed in the
brain, spinal cord, and digits of a mouse
embryo. Each of these domains of expression
is under the control of a different piece
of regulatory DNA (enhancer)
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coding region
brain enhancer
digit enhancer
spine enhancer
A particular gene may be expressed in the
brain, spinal cord, and digits of a mouse
embryo. Each of these domains of expression
is under the control of a different piece
of regulatory DNA (enhancer)
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Development from egg to adult