Transcript Developmental Biology, 9e

BIOL 370 – Developmental Biology
Compressed Final Lecture
Topics 18 - 22
Lange
BIOL 370 – Developmental Biology
Topic #18
Postembryonic Development
Lange
Due to time constraints, I have decided to compress
our final topics into a smaller format for presentation
during our last lecture.
I am starting at the point where I left off in lecture
last, and have already completed my discussion of
many topics in Topic 18.
Regeneration of a salamander forelimb
Effects of vitamin A (a retinoid) on regenerating salamander limbs
Retinoic acid
appears to help in
regeneration in a
variety of ways.
The limbs of these
salamanders had a
more rapid
regeneration when
the growing
regions were
bathed in this
vitamin a
derivative.
Proximalization of blastema respecification by retinoic acid
Organisms must effect a compromise between the energy allocated to reproduction and growth and
the energy allocated to the maintenance and repair of bodily tissues
Life span and the aging phenotype
The children in (B) have a condition called Hutchinson-Gilford Progeria. This is a
genetic condition characterized by the dramatic, rapid appearance of aging
beginning in childhood. Affected children typically look normal at birth and in
early infancy, but then grow more slowly than other children and do not gain
weight at the expected rate.
Survival curves for the U.S. population for the periods 1900–1902, 1949–1951, and 1999–2001
BIOL 370 – Developmental Biology
Topic #19
The Germ Line: Additional Concepts
Lange
In addition to creating their own body tissues, an animal must also
develop what are called germ cells. These cells will provide the
material and instructions for the next generation of that organism.
In most of the organisms we have studied, there is a clear
separation of germ cells from body (somatic) cells, but in some
organisms the demarcation is not so obvious (from class…. the
fern and the flatworm are examples).
In those groups that have a separate germ and somatic region, we
can see two different methods of specification:
• Autonomous germ cell specification (fruit flies for example)
• Induced germ cell specification (mammals for example)
Photomicrograph of a section through a mouse teratocarcinoma, showing numerous differentiated
cell types
A teratocarcinoma refers to a germ cell
tumor that is a mixture of teratoma with
embryonal carcinoma. This is a kind of
mixed germ cell tumor.
Teratomas have
been reported to
contain hair, teeth,
bone and, very
rarely, more
complex organs or
processes such as
eyes, torso, hands,
feet, or other limbs.
Growth of oocytes in the frog
The number of germ cells in the human ovary changes over the life span
BIOL 370 – Developmental Biology
Topic #20
Medical Aspects of Developmental Biology:
Birth Defects, Endocrine Disruptors, & Cancer
Lange
Fate of 20 hypothetical human eggs in the United States and western Europe
100%
84%
69%
42%
35%
31%
Down syndrome
Down’s Syndrome is a mixture of
various, albeit similar forms. The
most common form is more
specifically called Trisomy 21
Disorder. The CDC estimates that
about one of every ~700 babies born
in the United States each year is born
with Trisomy 21 Disorder.
Mosaic and relational pleiotropy
In this example, the gene’s
product is needed for both
tissues to develop
normally.
In this example, the gene’s
product is needed for one tissue,
but another product from the
initial tissue is requited to guide
normal development in a second
tissue.
Weeks of gestation and sensitivity of embryonic organs to teratogens
Fetal Alcohol Syndrome - a pattern of mental and physical defects that can
develop in a fetus in association with high levels of alcohol consumption during
pregnancy. Alcohol crosses the placental barrier and can stunt fetal growth or
weight, create distinctive facial stigmata, damage neurons and brain structures,
which can result in psychological or behavioral problems, and cause other
physical damage. The main effect of FAS is permanent central nervous system
damage, especially to the brain.
Comparison of a brain from an infant with fetal alcohol syndrome (FAS) with a brain from a normal
infant
Alcohol-induced craniofacial and brain abnormalities in mice
Genital anomalies can occur in women exposed to DES in utero
DES - Diethylstilbestrol is a synthetic
estrogen first synthesized in 1938.
• It is now classified as an endocrine
disruptor.
• From ~1940 to 1970, DES was
sometimes perscribed to pregnant
women to reduce the risk of
pregnancy complications and loss.
• Public awareness grew when in
1971, DES was shown to cause a
rare vaginal tumor in girls and
women who had been exposed to
this drug in utero.
Bisphenol A (BPA) – chemical used in some plastics and epoxy resins. First
used in 1957, BPA-laden plastic is clear, tough, yet flexible. Plastic of this sort
is used to make a variety of common consumer goods (for example, baby and
water bottles, sports equipment, and CDs and DVDs) and lining water pipes.
Bisphenol A causes meiotic defects in maturing mouse oocytes
In these images, mouse oocytes are shown. (A) is showing normal meiosis
associated with normal maturation. (B) is showing abnormal meiosis caused by
BPA exposure. The result in the organism is decreased or absent fertility or
abnormal chromosomal numbers in the eggs (aneuploidy).
Bisphenol A induces mammary lesions in mice
In more and more studies, BPA is being tied to increased instances of breast cancer.
Developmental estrogen syndrome is manifest in climbing rates of breast cancer and testicular
dysgenesis
The unfortunately growing rate of exposures to environmental estrogens (endocrine
disrupting compounds) has been associated with a variety of reproductive and
associated systems abnormalities.
Seminiferous tubules from the testes of (A) a control rat and (B) a rat whose grandfather was born
from a mother injected with vinclozolin
Vinclozolin is a fungicide used to control a variety of plant diseases
including blights, rots and molds agriculturally. It is also used on
turf on golf courses. It has been implicated in reproductive system
issues as well as can be seen in (B) below.
Effects of estrogen implants on different strains of mice
BIOL 370 – Developmental Biology
Topic #21
Ecological Development: Biotic, Abiotic, and
Symbiotic Regulation of Development
(Chapter 18 9th Edition; Chapter 19 10th edition)
Lange
Figure 18.1 Developmental plasticity in insects
Figure 18.3 The presence or absence of horns determines the male reproductive strategy in some
dung beetle species
Figure 18.4 Maternal diet can affect phenotype
End.
BIOL 370 – Developmental Biology
Topic #22
Developmental Mechanisms of Evolutionary
Change
Lange
Figure 19.9 Correlation between beak shape and the expression of Bmp4 in Darwin’s finches
Figure 19.10 Correlation between beak length and the amount of calmodulin (CaM) gene
expression in Darwin’s finches
Figure 19.11 Role of BMP4 and calmodulin (CaM) in beak evolution in Darwin’s finches
Allometry is the study of the relationship of body size to shape,
anatomy , physiology and finally behaviour, first outlined by
Otto Snell in 1892, D'Arcy Thompson in 1917 and Julian
Huxley in 1932.
Figure 19.12 Allometric growth in the whale head
Figure 19.23 Mice with mutations in the leptin genes are genetically obese
End.
BIOL 370 – Developmental Biology
Topic #23
Developmental Mechanisms of Xenoplastic
Specialization in Extra Terra Modalities
Lange
Correlation between eyestalk shape and body configuration in green aliens (Viridis peregrinus)
Please notice how the
eyestalk shape as well as
the surprise effect have
influenced the
development of green
alien (Viridis peregrinus)
morphology.
Proceed to the next
slide…
Suggestions to help in planning for the final examination in BIOL 370
The Biology 370 Final Examination is cumulative. That said,
however, the focus is that roughly ½ of the exam is based upon
“big picture, key concepts” associated with the first three
exams. You will be provided a fairly comprehensive review
sheet to help you in preparing for this comprehensive portion.
Follow the review sheet as a guide as you prepare for the
comprehensive portion.
The other half of the exam is organized over the topics covered
since exam #3 and follow the same sort of format and question
styles as you have experienced in past exams.
I thank you for having been a part of BIOL 370 – Developmental Biology. I greatly enjoy teaching
this course, and I am working hard to try to make it better each semester.