BIO 529 S05
Exam III
Name______________________
ID #_______________________
1. Fill in the blanks with the best answer from the list provided. Words may be used more than
once. (1 pt each)
estrogen
Mullerian duct
notochord
uterus
Sry
aromatase
hermaphrodite
Hox genes
neural crest
testosterone
telencephalon
metencephalon
dendrite
spinous layer
cornified layer
neurotrophin
limb bud
amniocentesis
ephrin
dihydrotestosterone
Leydig cells
primary sex cords
cortical sex cords
oviduct
chordamesoderm
doublesex
neural plate
neural groove
endocrine disruptor
diencephalon
myelencephalon
axon
basal layer
epididymus
autopod
limb field
In vitro fertilization
netrin
Autopod
Cornified layer
AER
Ventricular zone
glia
Netrin
Sertoli cells
Sex-lethal
Transformer
Telencephalon
Diencephalon
teratogen
Basal layer
Growth cone
Chorionic villus sampling
Estrogen
Leydig cells
Atrazine
dihydrotestosterone
Granulosa cells
Uterus
Oviduct
Cortical sex cords
Wolffian duct
thecal cells
organizer
vas deferens
teratogen
Sex-lethal
numerator proteins
neural tube
neural folds
atrazine
transformer
glia
growth cone
keratin
melanocyte
stylopod
progress zone
positional cloning
semaphorin
Mullerian inhibitory substance
granulosa cells
Sox9
marginal zone
intermediate mesoderm
Sertoli cells
denominator proteins
oligodendrocyte
primary neurulation
secondary neurulation
mesencephalon
intermediate zone
ventricular zone
granular layer
Schwann
zeugopod
apical ectodermal ridge
chorionic villus sampling
zone of polarizing activity
The most distal segment of the tetrapod limb
Outer layer of skin, comprised of dead cells
The epithelial layer of the progress zone
Actively dividing layer of the spinal cord
Cells that often serve to guide migration neurons
A diffusible axon guidance molecule that forms a gradient
Cells responsible for production of Mullerian inhibitory substance
Sex determination genes in Drosophila that encode proteins which
influence alternative splicing of mRNA
Part of the brain associated with olfaction
Part of the brain associated with vision
Substance or condition that causes non-heritable birth defects
Epidermal layer that is actively dividing
The tip of an extending axon
Method to collect cells from placenta to genetically analyze embryo
Substance that causes regression of the Wolffian duct
Cells of the testes that are derived from the mesenchyme
Specific compound that stimulates aromatase activity
Compound required for proper development of the prostate and penis
Female equivalent of Sertoli cells
Location where embryo is introduced after in vitro fertilization
Location where embryo is introduced after ZIFT
Gonadal region into which the female germ cells migrate
1
BIO 529 S05
Exam III
Name______________________
ID #_______________________
For all remaining questions, you must show your work or explain your reasoning to receive
any partial credit.
2a. Name two different types of viruses that have been utilized for human gene therapy trials. (3
pts)
retrovirus, adenovirus, adeno-associated virus, lentivirus
b. Explain at least two problems that have been encountered using these viral vectors. (4 pts)
Retroviruses integrate into the genome, therefore can disrupt normal genes. This
may result in unanticipated and undesirable effects. Several cases of leukemia
have been linked to insertions of retroviral gene therapy agents.
Adenoviruses have been tested for treatment of genetic diseases that affect the
lungs, such as cystic fibrosis. However, treatment with these agents has been
ineffective, largely because it is difficult to get efficient infection of the target cells.
3a. Label each layer or structure indicated by a box in the diagram of epidermis below. (8 pts)
(From top to bottom on left then right) Keratin granules, melanosomes, cornified layer,
granule layer, Malpighian layer, spinous layer, basal layer, melanocyte
b. What cell type would you find directly under the basal lamina? (2 pts)
Dermis
2
BIO 529 S05
Exam III
Name______________________
ID #_______________________
4a. Name the two actively dividing layers of neuronal stem cells in the cerebellum. (3 pts)
ventricular zone and external granular cell layer
b. What is the signaling molecule that maintains the outer proliferative layer of the
cerebellum and what cell layer produces that molecule? (4 pts)
Sonic hedgehog
5. Name the four populations of neural crest cells and one tissue that comes from each (8 pts)
cranial neural crest – cranial cartilage, bone, connective tissues, neurons, thymus, tooth
primordial, bones of jaw and ear
trunk neural crest – melanocytes, sympathetic ganglia, adrenal medulla, aortic nerves,
and dorsal root ganglia
vagral & sacral neural crest – parasympathetic ganglia of gut
cardiac neural crest – melanocytes, neurons, cartilage, connective tissue of arteries,
aortic septum
6. Based on your knowledge of sex determination in flies and mammals, fill in the table below
to indicate the expected outward sexual appearance (phenotype) for each situation indicated.
Phenotypes you may choose are: male, female, or intersex. (15 pts)
Genotype
XY with constitutively activated Sex lethal gene
XXY human
XXY fly
XXY fly triploid for all autosomes
XXY with deletion of Sry gene
XXY with normal Sry gene
XX with homozygous deletion of transformer gene
XY fly with deletion of several numerator genes
XY fly with deletion of several denominator genes
XX with homozygous deletion of androgen receptor
XY with homozygous deletion of androgen receptor
XX with constitutively active FGF9 gene
XX with duplication of Sox9 gene
XX with homozygous deletion of Sox9 gene
XY with homozygous deletion of Sf1 gene
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Phenotype
Female
Male
Female
Intersex
Female
Male
Male
Male
Female
Female
Female
Male
Male
Female
Female
BIO 529 S05
Exam III
Name______________________
ID #_______________________
7a. In the assigned reading from Riddle et al. (Cell paper from 1993), the authors used
misexpression of Shh to suggest that it could be the molecule responsible for the properties
of the ZPA. This was most clearly demonstrated by the implantation of cells expressing Shh
into the developing limb. Where in the limb were the cells implanted and what was the
outcome of the experiment? (4 pts)
Cells were implanted at the anterior side of the limb. This resulted in mirror image
duplication of the posterior portions of the limb, with the most posterior elements
present at both the anterior and posterior margins.
b. Based on the results described above and the model presented by the authors, what would
have been the expected result from loss of Shh in the developing limb? (2 pts)
Loss should result in the opposite effect, which would be loss of all posterior
elements of the limb. Only the most anterior elements should remain.
c. In the second assigned reading (Litingtung et al., from Nature 2002), the actual results of
the loss of Shh in the limb were reported. What was the phenotype? (2 pts)
Loss was consistent with b, namely that only the most anterior elements remained,
but only a single digit was seen in the autopod.
d. In the Nature paper, they also looked at loss of the Ci homologue, Gli3. What was the
expected phenotype of loss of Gli3 in the developing limb? What was the actual phenotype?
How are these results explained? (6 pts)
It was expected that loss of Gli3 should have the same result as loss of Shh, since
Shh activates Gli3. In reality, loss of Gli3 resulted in polydactyly and the loss of all
A/P asymmetry in the limb. This is interpreted as indicating that the functional form
of Gli3 is the repressor, Gli3R, and that the role of Shh is to reduce the amount of
Gli3R in the posterior of the limb. This would establish a gradient of Gli3R that is
higher in the anterior which would confer A/P asymmetry and somehow restricts
number of digits.
4
BIO 529 S05
Exam III
Name______________________
ID #_______________________
8. Based on your knowledge of tissue interactions during limb development, predict the
outcome of the following surgical experiments in chick embryos. For each, be sure to
indicate all limb segments that would be produced, whether each is wing or leg, and indicate
any altered polarities of the tissue. (14 pts)
a. The mesoderm underlying the early wing bud is transplanted to replace the mesoderm of
the leg bud after production of the stylopod.
To the leg stylopod, a complete wing would be added (stylopod, zeugopod, and
autopod).
b. The ectoderm of the early wing bud is transplanted to replace the ectoderm of the leg bud
after production of the stylopod.
A normal leg would be formed.
c. The tissue at the posterior of the early wing bud is removed and replaced with tissue from
the anterior of a different early wing bud.
This should look like the Shh mutant described above, with only one digit.
d. The tissue at the anterior of the early wing bud is removed and replaced with tissue from
the posterior of a different early wing bud.
This is the classis ZPA transplantation experiment and results in mirror-image
duplication of posterior as described above.
e. The mesoderm and ectoderm at the tip of a wing bud after production of the zeugopod is
transplanted to replace the mesoderm and ectoderm at the tip of a leg bud after
production of the stylopod.
To the leg stylopod, a wing autopod would be added.
f. The ectoderm tip of a wing bud after production of the zeugopod is added to the tip of a
leg bud after production of the stylopod.
To the leg stylopod, duplicated zeugopods and autopods would be added.
g. The mesoderm underlying the wing bud is removed after production of the stylopod and
replaced with mesoderm from a leg bud after production of the zeugopod.
To the wing stylopod, a leg autopod would be added.
5
BIO 529 S05
Exam III
Name______________________
ID #_______________________
9. Explain how the X:A ratio in Drosophila leads to the differential activation of a target gene
that will distinguish male from female. Be sure to include a description of the molecular
“measurement” of X:A ratio, how this molecularly initiates sex determination, the identity of
the target of X:A ratio regulation, and how that gene then distinguishes male from female. If
in doubt, provide more information rather than less. (10 pts)
See Text
6