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Basic Concepts of Experimental Embryology - PowerPoint PPT Presentation


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CDB 325-DB Bootcamp Goals: Learn the basics on the development of the model organisms used at Vanderbilt. Descriptive embryology (not experimental zoology, developmental biology, genetic manipulation, etc) Care and feeding Compare and contrast Course Management Director: David Bader

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slide1

CDB 325-DB Bootcamp

Goals: Learn the basics on the development of the model organisms used at Vanderbilt.

Descriptive embryology

(not experimental zoology, developmental biology, genetic manipulation, etc)

Care and feeding

Compare and contrast

Course Management

Director: David Bader

Student Director: Hillary Hager

Student Director (in training): Rachel Skelton

Coordinator: Kim Kane

Grades

There will be a test.

Attendance.

Asking questions/Participation.

Getting into it.

slide2

Anatomical Positions

Organisms, organ systems, and organs have names for the different surfaces and positions.

Next week, use the right terms when you examine embryos.

slide3

What “larger” questions in biology are best approached by Developmental Biology?

Differentiation

Morphogenesis

Growth

Reproduction

Evolution

Nature/Nurture

how one cell gives rise to many different cell types

generation of ordered forms comprised of organized cells

regulated cell growth is essential

instructions must be passed between generations

species diversity with colinearity of mechanism and genes

how the environment influences developmental processes

slide4

Things don’t always look as they seem.

Embryology is a moving target in terms of??

Morphogenesis

Cell division and migration

Gene expression and cell diversification

Reaction with the environment

More?

One question I have: When do larval forms arise in evolution?

slide5

Relationship of embryo and mother

There are differences. Any guesses?

Number of eggs/ovulation cycle

Site of fertilization

Site of embryonic development

Energy/raw materials

Others?

slide6

Who is this?

Imagine discovering something so fundamental.

What discoveries could have challenged this finding?

Genetics

Molecular Biology

Does ontology recapitulate phylogeny?

slide7

What are the major stages/events in embryogenesis?

Fertilization

Cleavage

Morula

Blastula

Gastrulation

Partitioning of germ layers

Organogenesis

Growth

Sexual maturation

Reproduction

Death

slide9

The 20th Century

Developmental Biology

T. Boveri & WS Sutton

chromosomal theory-complex structures that differ from one another within the same nucleus, responsible for developmental program. Interactions between nucleus and cytoplasm/ gradient hypothesis

N.Sevens and EB Wilson

sex chromosomes of insects, correlated nuclear structure (XX,XY or XO) with sexual development

TH Morgan

X-linked mutations/genetics and development

EG Conklin

lineage studies of Styela partita

H. Spemann

surgical manipulation of amphibian embryos, the organizer

Wilkins, Watson, Crick (Franklin?)

DNA as the genetic material

Nusslein-Volhard and Wieshaus

Merging genetics, experimental zoology and development

What’s next? What do you like is the next great discovery?

basic concepts of experimental embryology
Basic Concepts of Experimental Embryology
  • Homology versus Analogy
    • evolutionary implications
  • Fate mapping
    • the importance of observation
  • Cell Specification
    • how cells take on different fates
  • Gradients
    • the organization of morphogens
slide11

Here are Four HomologousStructures that are Derived from a Common Evolutionary Precursor. There are two pairs of AnalogousStructures that have a Common Function

Is this right?

1.13

basic concepts of experimental embryology12
Basic Concepts of Experimental Embryology
  • Homology versus Analogy
    • evolutionary implications
  • Fate mapping
    • the importance of observation
  • Cell Specification
    • how cells take on different fates
  • Gradients
    • the organization of morphogens
slide13

Conklin’s study of the Tunicate, Styela partita

These fate mapping studies were carried out by direct

observation and were facilitated because different cell types are normally pigmented in this organism (the sea squirt)

G1.7

basic concepts of experimental embryology14
Basic Concepts of Experimental Embryology
  • Homology versus Analogy
    • evolutionary implications
  • Fate mapping
    • the importance of observation
  • Cell Specification
    • how cells take on different fates
    • 4 basic experimental approaches
  • Gradients
    • the organization of morphogens
slide15

Basic Experimental Approaches to Examine Specification

Defect: observe development when one portion of embryo is destroyed (but not removed)

Isolation: remove portion of embryo and observe its development

Recombination: move one portion of the embryo to another part of the same embryo

Transplantation: same as 3. But here move to a DIFFERENT embryo

Mas?(I can think of a couple.)

slide16

Autonomous Specification/Mosaic Development

    • Characteristic of most invertebrates
    • Specification by differential acquisition of cytoplasmic molecules
    • Invariant cleavage patterns (identical cell lineages)
    • Blastomeres identical

What’s the experiment?

What does the outcome mean?

  • Characteristic of most invertebrates
  • Specification by differential acquisition of cytoplasmic molecules
  • Invariant cleavage patterns (identical cell lineages)
  • Blastomeres identical

What is the difference between “cell fate, cell specification and cell lineage”?

slide17

Autonomous Specification in Styela

each disassociated blastomere pair forms

structures they would have become in the embryo

isolation

3.8

slide18

Conditional Specification

    • the fate of a cell depends on its position and interactions
    • removal of cells can be compensated
    • Massive cell rearrangements and migrations usually occur
    • Regulative development occurs when interactions

that are dependent upon a cell’s neighbors is seen in most

vertebrate systems

transplantation

defect

What would the outcome be if this were a mosiac system?

slide19

Syncytial Specification (in Drosophila)

  • Characteristic of most insects where early nuclei share cytoplasm
  • Specification by interactions between cytoplasmic morphogens
  • Variable cleavage produce no rigid cell fate for specific nuclei
  • After cellularization, conditional development usually occurs

3.11

basic concepts of experimental embryology20
Basic Concepts of Experimental Embryology
  • Homology versus Analogy
    • evolutionary implications
  • Fate mapping
    • the importance of observation
  • Cell Specification
    • how cells take on different fates
  • Gradients
    • the organization of morphogens
slide22

Two Experimental Demonstrations

of Activin Gradients

The more activin a cell receives the “more” mesodermal the cell fate….

slide26

Nuclear Transplantation in Xenopus

(Briggs and King, 1952)

G4.5/4.6

slide28

Clone

Family

PhotoAlbum

Dolly and Bonnie, 2000

CC amd her nuclear donor “mother” Rainbow Shin et.al. Nature (2002) 415:859

Snuppy and somatic skin cell donor “father” Snuppy’s and her Surrogate Mother

Lee et al. Nature (2005) 436:641

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