lecture 1

Lecture 1

Course Outline

Central problem in Development

Terms

Cellular mechanisms of determination

Objectives

• Lectures: application of genetic analysis to problems in development. Emphasis on problem solving as opposed to rote memorization.

• Labs: Illustration of some basic techniques used in Developmental genetics. Lab report written in the format of a scientific paper.

Jan 12 Lecture 1 Introduction to developmental geneticsJan 19 Lecture 2 Introduction to genetic dissection: screens, complementation and epistasis.Jan 26 Lecture 3 Drosophila cell biologyFeb 2 Lecture 4 Modern Drosophila genetics Feb 9 Lecture 5 Anterior posterior axis formationFeb 16 Lecture 6 Anterior posterior axis formation continuedFeb 23 SLACK WEEK March 1 Lecture 7 MorphogensMarch 8 Lecture 8 Nuclear gradients and the habits of developmental signaling pathwaysMarch 15 Lecture 9 Short course on C. elegans cell biology and genetic analysis.March 22 Lecture 10 Lateral inhibition—emergent properties in developmentMarch 29 Lecture 11 Short course on Evolution and Development.April 5 Lecture 12 Experimental approaches to Evo Devo. Paper due.

Schedule of Lectures

Date for the Midterm examination

Monday February 27, 2012 This is the Monday right after slack week 7-10PM.

This midterm will cover materialup to Lecture 6 Anterior Posterior axis.

The course web site can be foundat instruct.uwo.ca/biology/4540g

This web site contains all the information you need for thiscourse. Consult it. Explore it.

Jan 9/10 NO LAB

Jan 16/17 Lab 1 Preparation of first instar larval cuticles (test)

Jan 23/24 Lab 2 Ectopic expression of Fushi tarazu (come in the day before). Fixation of embryos for Labs 3&4 (test)

Jan 30/31 Lab 3 Engrailed antibody staining (long lab) (test)

Feb 6/7 Lab 4 Wingless in situ hybridization (come in the day before; long lab) (test)

Feb 13/14 Lab 5 Beta-galactosidase staining for assaying ftz enhancer activity. (test)

NO MORE LABS

Schedule of the Labs and in class tests

Jan 9/10 NO LAB

Jan 16/17 Lab 1 Preparation of first instar larval cuticles

Jan 23/24 Lab 2 Ectopic expression of Fushi tarazu (come in the day before). Fixation of embryos for Labs 3&4

Jan 30/31 Lab 3 Engrailed antibody staining (long lab)

Feb 6/7 Lab 4 Wingless in situ hybridization (come in the day before; long lab)

Feb 13/14 Lab 5 Beta-galactosidase staining for assaying ftz enhancer activity.

NO MORE LABS

Long labs

The lab test on the readings

Why am I doing this to you? In the pastI expected students to read the paperson their own before coming to the lab.Over the years it become clear that thiswas not occurring. Reading in the firsthalf of the term saves a lot of pain later.Since I know this, I am being a pain now.

Format of the test on the readings

You will have 5 minutes to answerone question at the beginning of the lab.

The question asked will be differenton Monday and Tuesday.

This and the next lecture will focuson definition of the terms and basicgenetic concepts used in Developmentalgenetics.

The central problem in Development

“How is the information stored in linear DNAtransformed over time into a three dimensionalmulticellular organism?”

From this perspective the problem seemslimitless.

However, the size of the genome providesa limit on the problem because all informationrequired for hand development is somehowencoded in the genome.

What is animal development?


• It is an essential part of our and all animal life cycles.


• It is an essential part of our and all animal life cycles.

• At the present time only life can beget life.

General animal life cycle

Soma

Germ-line

fertilization fertilization


Soma

Germ-line


Somatic germ-linedivision


Soma

Germ-line


Somatic germ-linedivision

Life does not begin at fertilization; it is a continuousprocess.

What are the characteristics of animal development?

Development at its most basic level.

Single celledZygote

Decisions

Complex multicellular organismof many specialized cell typesand organs.

Two terms used in Developmental Biology.

Determination

Differentiation

More terms

Cell specification

versus

Pattern formation

Examples of cell specification

Lens: each cell as it differentiates becomestransparent.

Red blood cell: no nucleuspacked with hemoglobin.

Example of pattern formation

You distinguish an arm froma leg by its shape and not bywhat it is made up of whichis basically the same stuff:bone, muscle, nerves etc..

This is an abstract ability, because shape is a quality defined only by what it is.

Cellular mechanisms of determination

• Intrinsic

• Extrinsic

mRNA

protein

Anterior Posterior

Example of an intrinsic mechanism:Assymetric determinant

Bicoid mRNA and protein areassymetrically localized in the cell.

Extrinsic mechanisms

• A) Lateral inhibition

• B) Induction

Lateral inhibition during neurogenesis in Drosophila.

Example of an emergent property because before the processstarts you can not tell which cell will be neurogenic and whichwill be epithelial.

Delta ligand

Notch receptor

Start off with identical levels of expression intwo cells.

Delta ligand

Notch receptor

Start off with identical levels of expression intwo cells.

No Net signal

Due to a stochastic (random, chance) event one cell expressesmore Delta ligand than the other.

The net signal is in this direction.The activation of Notch receptor results indecreased Delta expression.

Dl

When Notch or Delta are absent, the ectoderm cellsbecome neurogenic. The cell that becomes the neuroblastinhibits the surrounding cells from this fate, and telling themto become epithelial cells instead. Lateral inhibition.

Neuroblast Epithelial

Notch

Neuroblast

Epithelial

Induction

1

2

A cell or group of cells removedfrom a second cell

that directs the developmentalfate of a second cell or group ofcells.

Example of induction

Anchor cell-gonad

signals

Epidermis

Vulva

What molecules control determination?

Gut

Brain

Analysis of gene regulation: cis regulation.

gene something

embryo of something

ORF

ATG

Translational fusion to a reporter gene

Reporter gene

ATGGFP

TATA

Regulatory regions of the gene

ATGGFP

TATA


Gut

Brain

ATGGFP

TATA


Gut

Brain

Gut

Brain

ATG GFP

TATA

ATG GFP

TATA

ATG GFP

TATA

ATG GFP

TATA

ATG GFP

TATA

Mutagenesis

Gut

Brain

Gut

Brain

ATG GFP

TATA

ATG GFP

TATA

ATG GFP

TATA

ATG GFP

TATA

ATG GFP

TATA

Mutagenesis

Gut

Brain

Gut

Brain

Gut

Brain

ATG GFP

TATA

ATG GFP

TATA

ATG GFP

TATA

ATG GFP

TATA

ATG GFP

TATA

Mutagenesis

Gut

Brain

Gut

Brain

Gut

Brain

Gut

Brain

ATG GFP

TATA

ATG GFP

TATA

ATG GFP

TATA

ATG GFP

TATA

ATG GFP

TATA

Mutagenesis

Gut

Brain

Gut

Brain

Gut

Brain

Gut

Brain

Gut

Brain

ATG GFP

TATA

ATG GFP

TATA

ATG GFP

TATA

ATG GFP

TATA

ATG GFP

TATA

Mutagenesis

Gut

Brain

Gut

Brain

Gut

Brain

Gut

Brain

Gut

Brain

Gut enhancer

Brain enhancer

Gut silencer

ATG

Heterologous TATA box

Transcriptional fusion

Gut

Brain

Gut enhancer

Brain enhancer

Gut silencer GFP

ATG GFP

Gut

Brain

ATG GFP

Gut

Brain

ATG

ATG

Gut enhancer

Brain enhancer

Gut

Brain

Gut

Brain

ATG GFP

Gut

Brain

ATG

ATG

Gut enhancer

Brain enhancer

Gut

Brain

Gut

Brain

ATGGut enhancer

Gut silencer Gut

Brain

Important property:

Necessary and Sufficient

Developmental pathways

Transcription factor signal transcription factor pathways

TF A SF Signaltransduce

TF B

Ci Wingless FrizzledDshArm

LefEn

En Hedgehog PatchedSmooth

Ci

lecture 1

Documents

lab report

long lab testfeb

labslong labsthe lab

course outlinecentral

short course

long labfeb

problem seemslimitless

betagalactosidase staining