21st Century Biology

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21st Century Biology

• Experimental Biology for
• Pre-College Students
• An Introduction to Modern Research Techniques and
  Scientific Writing

www.21bio.org
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Volume 2-Issue 1
September-October 2002
Brainstorm
Alcohol All Kinds of Bad
and, in quantities large enough to
be toxic, death. Understanding how alcohol
creates this eclectic spectrum of effects in
people has always been difficult for scientists.
Alcohol is a great solvent (it can dissolve
things easily) fats dissolve particularly well.
Because cell membranes in the brain are made of
lipids (Fatty compounds), alcohol can seep into
brain cells. However alcohol just being in the
cells does not create its effects. Most
recreational drugs effect people by binding to
nerve receptors, and preventing the normal
function of nerve transmitters
and the nervous system as a whole. Alcohol
however, does not have its own nerve receptor to
bind to, as do drugs like heroine and cocaine.
Scientists now believe that alcohol can bind to a
wide variety of nerve receptors. Because alcohol
can affect different kinds of nerve receptors, it
can create many different reactions. Alcohol is
an addictive substance. Addicted people are said
to have alcoholism. Scientists continue to try
to understand alcohol on the molecular level to
try to create a drug to treat people with
alcoholism. Resources www.dana.org/articles/dbk
_0298.cfm - 18k - 25 Sep 2002
Alcohol is one of the worlds oldest drugs. Ethyl
alcohol is the common alcohol found in beverages,
it is abundant because it is a byproduct of
yeasts cellular respiration. When people consume
large amounts of alcohol it affects the brain and
can cause varied reactions First comes a
"high," then, with larger amounts, sedation,
unconsciousness,
Thigmomorphogenesis 2 Brain Awareness Week 2 Z
ebrafish 3 Telemicroscopy 3 Chesapeake Bay Fou
ndation
4 Wordfind 4
Editors Annie Lagomarcino Addie
Leader-Zavos Reid Ravin
Try to find your way through this fun maze!
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Brain Awareness Week
A Brain
A Basic Neuron
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The Neurophysiology, Behavior, and Bioacoustics
of Insects
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Immunocytochemistry in Conjunction with the NIH
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Weakly Electric Fish (WEF)
The sound that you are hearing is a clicker
that is eating
The picture on the right shows a graph of the
field of an electric fish. Note that the field is
strongest near the tail and rapidly weakens as
the distance from the fish increases. This gives
a fairly accurate sense of distance, if not an
exact shape impression.
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WEF Applications

• Military Sensory Applications
• Electric Fish as Biosensors
• Medical Applications
• Non-Contact Human-Computer Interfaces

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Thigmomorphogenesis
Monocots vs. Dicots
Arabidopsis
RNA Extraction
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Thigmomorphogenesis Setup
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Zebrafish

• The Zebrafish Project was Started at Sidwell
  Friends by Biology I Students
• Goals
• Start a Zebrafish Colony
• Investigate Developmental Mutations of Notochords
• Write LiCl Treatment Protocols
• Focus on Spadetail, Floating Head, and Hedgehog
  Mutations

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Genome Duplication Events in Zebrafish Evolution
http//www.ittiofauna.org/webmuseum/agnati/
Zebrafish
Agnatha
Osteichthyes
Teleosts
Ancestral chordate
Vertebrata
Pufferfish
Chondrichthyes
Urochordata
http//www.ucmp.berkeley.edu/vertebrates/basalfish
/chondrolh.html
http//www.cosmiverse.com/science10260102.html
Cephalochordata
Fig. 2
Genome duplication event
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With Wnt signal
No Wnt signal
GSK3ß
Wnt
P
ß-catenin
Ubiquitin-proteosome system
Tcf3
Wnt
RNA transcriptase
Frizzled
Nucleus
Hox genes
GSK3ß
The Wnt signaling pathway

• A neighboring cell secretes Wnt to the target
  cell.
• Wnt binds to the target cells receptor,
  frizzled.
• Frizzled blocks the GSK3ß complex, which normally
  phosphorylates ß-catenin.
• Unphosphorylated ß-catenin binds to the Tcf3
  complex, a transcription repressor in the
  nucleus.
• Inhibiting the Tcf3 complex permits the
  transcription of Hox genes that regulate AP axis
  development.

ß-catenin
Tcf3
Key
Transcription of Hox genes
inhibition
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The Hox expression gradient and establishment of
the AP axis
Hox gene cluster
anterior-determining genes
posterior-determining genes
posterior
anterior
The Hox expression gradient acts like a
continuous spectrum of different colors. For
example, the embryos head is determined by 100
red (the first Hox gene) and 0 other (the other
Hox genes). A middle segment would be determined
by 50 yellow (a middle Hox gene) and 50 green
(the next Hox gene). By this mechanism, Hox
regulates normal embryonic differentiation,
leading to neurogenesis and organogenesis both
along the anterior-posterior (AP) axis and along
the dorsal-ventral (DV) axis.
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The Floating Head Mutant
Gastrulation
wt
flh
Cells that have not entered the hypoblast
continue to maintain normal flh gene expression.
Cells in flh mutants that have involuted and
entered the hypoblast show an abrupt loss of flh
expression.
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The Sonic-You (Syu) Gene
Sonic-You (syu) gene encodes for sonic hedgehog
(shh) protein and is required for somite
patterning.
The syu mutant is missing the syu Gene and the
shh signaling pathway does not function
properly, and so what the shh gene encodes cannot
be distributed.
Shh signaling pathway
Smoothened is a protein believed to activate an
intracellular signaling cascade. It forms a
receptor complex with Patched.
Patched is a protein thought to be the
receptor that binds the shh gene and
induces conformational changes in itself and
Smoothened.
When Patched represses Smoothened, the shh
protein cannot be involved in the organization
and patterning of tissues in vertebrates or
control a wide range of differentiation processes
during vertebrate development, especially
floor plate development. Mutations develop when
this occurs.
Wnt4b is a protein expressed exclusively in the
floor plate. If shh is missing, the wnt4b
cannot Function properly, so the lateral floor
plate is not developed fully, sometimes not at
all. Many mutations display these
characteristics.
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The Spadetail Mutant
The Spadetail gene encodes for a
T-box transcription factor that encodes a
message that is expressed in the blastoderm
soon after initial zygote gene expression.
After gastrulation, its expression is restricted
to paraxial mesoderm and later in the
developing tail bud.
spt
Zfin.org
Together with another gene, ntl, spadetail
mediates the signaling of fibroblast growth
factor (FGF).
The spadetail mutant does not express the
spadetail gene. The t-box gene that corresponds
to the spadetail mutants is tbx16.
FGF is responsible for trunk and tail Formation.
Spadetail is responsible Specifically for FGF
signaling in the trunk non-notochordal mesoderm.
Without the spadetail gene, mutants have major
trunk mesoderm deficiencies, but relatively
normal tail and notochord development.
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Trial 1
Trial 2
Trial 3
Trial 4
ZFISH Experiment 1 Experiment 2 Experiment 3 Control
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Telemicroscopy Tomography
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Locations of Microscopes
California State University Stanislaus Confocal
Microscope
IN-VSEE Arizona State University Scanning Probe
Microscope
National Center for Microscopy and Imaging
Research UCSD Transmission Electron Microscope
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