Zebrafish Flashcards
advantages of Zf as model organism
transparent eggs
rapid embryonic development (major organs in 24 hrs.)
quick generation time (2-3 months to reach reproductive stage)
ease of maintenance
number of eggs laid by female
100-200 eggs
term which means “found at bottom of a body of water” used to describe Zf eggs
demersal (sink to bottom)
internal or external fertilization?
external
part of egg that the first sperm attaches to
microvilli
enumerate the 2 mechanisms to prevent polyspermy
- microvilli elongate to form fertilization cone and micropyle becomes plugged
- calcium dependent cortical granule reaction
the clear cytoplasm that sits atop the yolky sphere
blastodisc
when does cleavage begin? what is the time interval between each cleavage?
after 45 minutes; occurs every 15 minutes
staging series for Zf
by Kimmel et al.
type of cleavage
meroblastic
first sign of fertilization
transparent egg
the organizer region where the deep cells converge towards the dorsal side (analogous to Koller’s sickle region)
embryonic shield
The first 6 cleavages are ____. The succeeding cleavages are now ____.
synchronous; metasynchronous
cleavage wherein waves of cell divisions pass through the blastoderm and a multi-tiered mound of cells is produced
metasynchronous
enumerate the 3 distinct layers in the blastula
yolk syncytial layer (YSL)
enveloping layer (EVL)
deep cells
protective outer layer of blastula that is eventually sloughed off
periderm
the cells that become the embryo
deep cells
spreading of blastoderm down around the yolk
epiboly
movements within the YSL during epiboly are due to?
action of microtubules and their associated motor proteins
the turning on of the embryonic genome that begins at the 10th cell division
mid-blastula transition
the messages stored in the egg during oogenesis that controlled development
maternal mRNA
process where deep cells turn inward and spread on top of the YSL
involution
the thickened ring of deep cells produced during the initial stages of involution
germ ring
stage with 100% epiboly
bud stage
enumerate the 3 sensory placodes found on the head
olfactory placodes
otic placodes
lens placodes (with optic cups)
when organogenesis begins
24 hours into development
enumerate the 2 structures formed when the neural plate folds inward
neural keel and neural rod
the series of canals containing sensory structures that detect low-frequency motions in water
lateral line system
the sensory structures found in the lateral line system
neuromasts
when does the embryo hatch?
between 48-72 hours
chromatophore that contains light-reflecting crystals (usually guanine)
iridophores
term used to describe breeding that is dependent on light and dark cycles
photoperiodic
specific light/dark cycle (in hours) needed for breeding
14 hours light, 10 hours dark
optimum temperature in raising Zf
28.5 degrees Celsius
differentiate male Zf from female Zf
males: longer, slimmer, more yellow
females: plumper and more silvery
best food source for high-protein diet of Zf
brine shrimp
ratio of males to females in breeding tank
1 male to two females
when mating usually occurs
dawn/light period
food of Zf when below 10 days old
baby fish food or paramecia
enumerate the 2 solutions that can be used to maintain Zf embryos
- egg water
2. 10% Hank’s stock solution
used to anesthetize embryos
tricaine
used to dechorionate
dilute pronase
ciliated organ of asymmetry in the zebrafish embryo that initiates left-right development of the brain, heart and gut.
Kupffer’s vesicle
the phylotypic stage in Zf development
pharyngula stage
enumerate 3 effects of cold temperature (~18 degrees) on Zf development
inhibits microtubules
inhibits ooplasmic segregation?
inhibits axis formation?
effect of high temperature (~40 degrees) on development
first mitotic division prevented
diploids become tetraploids
substance that can cause birth defects (include examples of these)
teratogens (ex. mercury, thalidomide, alcohol, vitamin A)
usually prescribed to people with bipolar disorder
lithium carbonate
enumerate the 5 teratogenic effects of lithium
- Ebstein anomaly (heart)
- spina bifida
- “floppy infant syndrome” (weak, unresponsive baby)
- exo-gastrulation (archenteron evaginates instead)
- dorsalized embryo (recall Wnt/β-catenin pathway)
describe the relationship of the following: glycogen synthase kinase (GSK), β-catenin, lithium, inositol triposphate
- lithium inhibits GSK, which inhibits β-catenin
2. lithium depletes inositol triphosphate in PIP cycle
enumerate the derivatives of vitamin A
- β-carotene
- vitamin A/retinol
- retinal
- retinoic acid
- tretinoin
- isotretinoin
enumerate 4 teratogenic effects of retinoic acid
- microcephaly
- microphthalmia
- craniofacial defects
- cardiovascular defects (ex. teratology of Fallot)
- thymus defects
- reduced limbs
broken down to retinoic acid when exposed to sunlight
methoprene
a posteriorizing signal known to influence Hox gene expression
retinoic acid
enumerate 3 teratogenic effects of alcohol
- fetal alcohol syndrome (face, heart, mental retardation)
- fetal alcohol effect
- cyclopia (only 1 eye)
enzyme that breaks down alcohol. is this found in embryos?
alcohol dehydrogenase; NOT in embryos
enumerate 4 examples of endocrine disruptors
- dioxin
- DDT
- p-nonylphenol
- phthalates
enumerate examples of behaviors that can be observed
- touch stimulus
- phototactic/negative phototactic response (towards/away from light)
- mating behavior
- dominance hierarchy
2 dyes used for whole mounts (include what they stain)
- alcian blue - stains glycosaminoglycans of cartilage at low pH
- alizarin red - stains calcium in bones at high pH
embryonic primordium determined to form specific organ
anlage
exogenous substances that interfere with normal hormone function
endocrine disruptors
precursor to pectoral and pelvic fins
fin bud
type of egg (in terms of yolk amount)
macrolecithal
the segregation of specific informational molecules within the cytoplasm to different regions of egg
ooplasmic segregation
neuromeres of hindbrain
rhombomere
