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History of Developmental Biology

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Embryology vs. Developmental Biology

Developmental Biology: Includes the

study of post-embryonic changessuch as growth/maturation,

metamorphosis, regeneration, aging.

Embryology: Descriptive study of

embryonic development includes allmulticellular organisms (plants,

animals, fungi).

Developmental Biologyis descriptive but also

incisive: what are the

mechanisms?

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5th century BC :

Aristotle favored epigenesis

17th century:

Marcello MalpighiChick embryology description(s) should

have confirmed Aristotles ideas

Preformation regained popularity

History: Epigenesis vs. Preformation

Preformation: Everything in the embryo is pre-formed and simply

grows during development.

Epigenesis: New structures arise progressively during development.

A preformed embryo(homunculus) within

sperm (1694)

Malpighis drawings ofchick embryos (1673)

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19th century:More descriptive embryology

Evolution: ontogeny recapitulates phylogeny

Cell Theory

Genetics + Development

Germ cells vs. somatic cells (Weissmann)

History: Cell Biology and Genetics

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Genes Proteins Cell Activities Developmental Processes

History: Cell Biology and Genetics

19th century:More descriptive embryology

Evolution: ontogeny recapitulates phylogeny

Cell Theory

Genetics + Development

Germ cells vs. somatic cells (Weissmann)

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19th century:More descriptive embryology

Evolution: ontogeny recapitulates phylogeny

Cell Theory

Genetics + Development

Germ cells vs. somatic cells (Weissmann)

History: Cell Biology and Genetics

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History: Nuclear Determination vs. Regulation

The mosaic model (Weismann): nuclear determinants are asymmetrically

distributed in zygote these determine fate of embryonic cells.

The regulation hypothesis suggests that embryonic development can adjust

to the loss of cells.

Rouxs experiment (1880s) on

frog embryos supported the

mosaic model

Drieschs experiment (1880s) on

sea urchin embryos supported

the regulation hypothesis

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20th century:

Johannsen genotype = phenotype(gene X environment interaction)

Mangold and Spemann - Induction: One cell (or tissue)influences the development of another cell (or tissue).

History: Genotype vs. Phenotype, Induction

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Throughout history, and today :

Model organisms

Mouse, chick,Xenopus, zebrafish,Drosophila, c. elegans, arabidopsis

Model Organisms

MOUSE (Mus musculus)

Advantages: Genetic manipulation, history of use, mammal, fast generation time.

Disadvantages:In utero development, costly.

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Throughout history, and today :

Model organisms

Mouse, chick,Xenopus, zebrafish, drosophila, c. elegans, arabidopsis

Model Organisms

CHICK (Gallus domesticus)

Advantages:In ovo development, history of use, amniote.

Disadvantages: Genetic manipulation not (yet?) possible; large ns difficult.

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Throughout history, and today :

Model organisms

Mouse, chick,Xenopus, zebrafish, drosophila, c. elegans, arabidopsis

Model Organisms

AFRICAN CLAWED FROG

(Xenopus laevis and Xenopus tropicalis)

Advantages:In ovo (rapid) development, large embryos, history of use, inexpensive.

Disadvantages:X. laevis is tetraploid.

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Throughout history, and today :

Model organisms

Mouse, chick,Xenopus, zebrafish, drosophila, c. elegans, arabidopsis

Model Organisms

ZEBRAFISH (Danio rerio)

Advantages:In ovo (rapid) development, genetic manipulation, history of use, inexpensive.

Disadvantages: ???? (o.k., so Im biased)

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Throughout history, and today :

Model organisms

Mouse, chick,Xenopus, zebrafish, drosophila, c. elegans, arabidopsis

Model Organisms

FRUIT FLY (Drosophila melanogaster)

Advantages:In ovo (rapid) development, genetic manipulation, history of use, inexpensive.

Disadvantages: Invertebrate

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Throughout history, and today :

Model organisms

Mouse, chick,Xenopus, zebrafish, drosophila, c. elegans, arabidopsis

Model Organisms

ROUNDWORM (caenorhabditis elegans)

Advantages:In ovo development, genetic manipulation, history of use, inexpensive.

Disadvantages: Invertebrate

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Throughout history, and today :

Model organisms

Mouse, chick,Xenopus, zebrafish, drosophila, c. elegans, arabidopsis

Model Organisms

MOUSE-EAR CRESS (arabidopsis thaliana)

Advantages: Rapid generation time, genetic manipulation, history of use, inexpensive.

Disadvantages: As a plant model, not many.

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Modern Developmental Biology

Developmental genetics

Diseases and disorders of development/teratology

Tissue repair and replacement/stem cells

Aging and cancer

Agriculture and food science

Evolutionary biology

Applications

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An introduction to the Developmental Biology literature

Journals (original research articles = primary literature):

Developmental BiologyDevelopmental Dynamics

Developmental NeurobiologyBMCDevelopmental Biology

Development,Genes and Evolution

Differentiation

Genes and DevelopmentInternational Journal of Developmental Biology

Development

DevelopmentalCell

Mechanisms of Development

Science

NatureProceedings of the National Academy of Science

Cell

Neuron

Search via PubMed: http://www.ncbi.nlm.nih.gov/sites/entrez

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Most research articles involve the use of model organisms to probe the function of

genes/proteins for a specific developmental process.

Retinal Homeobox 1 is Required for Retinal Neurogenesis

and Photoreceptor Differentiation inEmbryonic Zebrafish

Most make use of gain-of-function (GOF) or loss-of-function (LOF) approaches, using

genetic, molecular, or pharmacological tools to manipulate the target gene/protein.

LOF approach = antisense (morpholino) oligonucleotides targetingrx1 and rx2

Others will utilize cell/tissue transplantation techniques to probe developmental

potential of those cells/tissues

An introduction to the Developmental Biology literature

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Most of the data are collected as images showing histology of the developing structure

of interest, and/or gene expression (in situ hybridization to localize mRNA, orimmunocytochemistry to localize corresponding protein) within that structure.

There is a LOTof jargon.

An introduction to the Developmental Biology literature