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Developmental biology

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Developmental biology Definition: Field of biology that studies how a single cell (the fertilized egg) gives rise to a fully grown organism. Draw out embryonic ... – PowerPoint PPT presentation

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Title: Developmental biology


1
  • Developmental biology
  • Definition
  • Field of biology that studies how a single cell
    (the fertilized egg) gives rise to a fully grown
    organism.
  • Draw out embryonic development from 1-cell stage,
    cleavage, blastula, gastrula, germ layer
    formation, body plan development, neurulation,
    organogenesis
  • Why study it (why do people get excited about the
    topic? Complexity, beauty, imaging, relevance
    (human congenital defects, cancer)
  • Why have a course in it? (most of what you have
    studied so far has been intracellular biology,
    focusing on molecules and what happens inside
    individual cells one important aspect of biology
    that has not yet been covered is how cells
    communicate with each other, how they form
    multicellular organisms, how cells form different
    tissues, and how these different tissues form
    organs that in turn interact with each other).

2
  • Questions
  • axis determination (AP, DV, LR) Q. how do you
    break the symmetry of the egg? Sperm entry,
    localized determinants
  • cell differentiation, cell proliferation, cell
    growth
  • cell migration, polarization (symmetric vs
    asymmetric cell division), cell shape (giving
    cells different morphologies, e.g. neurons), cell
    death
  • morphogenesis (how cells come together to form
    tissues and how these tissues migrate)
  • organogenesis
  • timing (biological clock)
  • aging
  • germ cell development, fertilization
  • stem cells (what are they (multipotency, ability
    to self-renew), why did they become so trendy
    (Dolly the sheep, 1997, showed that cloning was
    possible development of human ES cells, 1998))
  • regeneration
  • evo-devo (a field of biology that compares the
    developmental processes of different animals in
    an attempt to determine the ancestral
    relationship between organisms and how
    developmental processes evolved.)
  • Q. How efficient is human development? (talk
    about implantation)

3
Human reproduction is an inefficient process
50 of concepti do not implant (implantation 8-10
dpf, Heart beat at 21 dpf). a further 30 die
and abort after implantation.
3-4 of all live births possess a
macroscopically visible congenital defect
(120,000 babies/year in the USA).
1 of all babies are born with a heart defect.
20 of neonatal deaths are caused by congenital
defects (the leading cause of neonatal death in
the USA)
congenital disorders are the cause of 50 of
pediatric admissions in the USA
Developmental defects seen at birth are caused by
defects in the cellular processes of development.
4
  • Developmental biology
  • Model systems
  • Worm (C. elegans)
  • Fly (Drosophila melanogaster)
  • Fish (zebrafish, medaka)
  • Mouse
  • Xenopus (laevis, tropicalis)
  • Chick (Quail)
  • Sea urchin (echinoderm), ascidians (ciona
    intestinalis, savigni) (urochordate (tunicate)
    (notochord in larvae), hydra (cnidaria,
    invertebrate), planarians (flatworm), arabidopsis
    (weed) ( other plants), axolotls (and other
    salamanders), chlamydomonas (unicellular green
    alga, protozoan), yeast (?),
  • Many systems available which one to use most
    powerful one where you can study your questions
    of interest. (also, many of these model systems
    are used to study processes other than
    developmental biology).

5
  • Developmental biology
  • Tools
  • - Forward genetics
  • - Reverse genetics (is gene x necessary)
    (mutation, RNAi)
  • - Gain-of-function expts (is gene x sufficient)
    (mRNA injections, transgenics various levels of
    sophistication, gal4-uas, temporal and spatial
    control)
  • - Where is function of gene x required? Creating
    genetic mosaics (genetic, transplants)
  • Imaging (live, gene and protein expression)
  • - Experimental embryology (cell or tissue
    ablations, bead implantation, chick-quail
    chimeras)

6
  • Developmental biology
  • Course
  • Discussions
  • one paper per session
  • Proposals where to identify topics?

7
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8
C. Elegans (adult 1 mm in length)
9
C. Elegans development (embryo about 50 ?m in
length)
10
Xenopus laevis
AP
V
D
VP
D
A
P
V
11
Early developmental stages of Xenopus laevis
2.5 hpf
5 hpf
10 hpf
3.5 hpf
hpf hours post-fertilization
12
Early developmental stages of Xenopus laevis
Cleavage movie
13
Developmental stages of Xenopus laevis
14
Gastrulation the ultimate cell migration problem
Danilchik movie
15
Gastrulation and Neurulation highly
coordinated tissue movements
Keller neurulation movie
16
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17
Zebrafish embryonic development
18
http//anatomy.ucsf.edu/Pages/devbio/course.htm
19
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20
http//www.nature.com/milestones/development/miles
tones/index.html
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