Zebrafish

Question 1

advantages of Zf as model organism

Answer 1

transparent eggs
rapid embryonic development (major organs in 24 hrs.)
quick generation time (2-3 months to reach reproductive stage)
ease of maintenance

Question 2

number of eggs laid by female

Answer 2

100-200 eggs

Question 3

term which means “found at bottom of a body of water” used to describe Zf eggs

Answer 3

demersal (sink to bottom)

Question 4

internal or external fertilization?

Answer 4

external

Question 5

part of egg that the first sperm attaches to

Answer 5

microvilli

Question 6

enumerate the 2 mechanisms to prevent polyspermy

Answer 6

1. microvilli elongate to form fertilization cone and micropyle becomes plugged
2. calcium dependent cortical granule reaction

Question 7

the clear cytoplasm that sits atop the yolky sphere

Answer 7

blastodisc

Question 8

when does cleavage begin? what is the time interval between each cleavage?

Answer 8

after 45 minutes; occurs every 15 minutes

Question 9

staging series for Zf

Answer 9

by Kimmel et al.

Question 10

type of cleavage

Answer 10

meroblastic

Question 11

first sign of fertilization

Answer 11

transparent egg

Question 12

the organizer region where the deep cells converge towards the dorsal side (analogous to Koller’s sickle region)

Answer 12

embryonic shield

Question 13

The first 6 cleavages are ____. The succeeding cleavages are now ____.

Answer 13

synchronous; metasynchronous

Question 14

cleavage wherein waves of cell divisions pass through the blastoderm and a multi-tiered mound of cells is produced

Answer 14

metasynchronous

Question 15

enumerate the 3 distinct layers in the blastula

Answer 15

yolk syncytial layer (YSL)
enveloping layer (EVL)
deep cells

Question 16

protective outer layer of blastula that is eventually sloughed off

Answer 16

periderm

Question 17

the cells that become the embryo

Answer 17

deep cells

Question 18

spreading of blastoderm down around the yolk

Answer 18

epiboly

Question 19

movements within the YSL during epiboly are due to?

Answer 19

action of microtubules and their associated motor proteins

Question 20

the turning on of the embryonic genome that begins at the 10th cell division

Answer 20

mid-blastula transition

Question 21

the messages stored in the egg during oogenesis that controlled development

Answer 21

maternal mRNA

Question 22

process where deep cells turn inward and spread on top of the YSL

Answer 22

involution

Question 23

the thickened ring of deep cells produced during the initial stages of involution

Answer 23

germ ring

Question 24

stage with 100% epiboly

Answer 24

bud stage

Question 25

enumerate the 3 sensory placodes found on the head

Answer 25

olfactory placodes otic placodes lens placodes (with optic cups)

Question 26

when organogenesis begins

Answer 26

24 hours into development

Question 27

enumerate the 2 structures formed when the neural plate folds inward

Answer 27

neural keel and neural rod

Question 28

the series of canals containing sensory structures that detect low-frequency motions in water

Answer 28

lateral line system

Question 29

the sensory structures found in the lateral line system

Answer 29

neuromasts

Question 30

when does the embryo hatch?

Answer 30

between 48-72 hours

Question 31

chromatophore that contains light-reflecting crystals (usually guanine)

Answer 31

iridophores

Question 32

term used to describe breeding that is dependent on light and dark cycles

Answer 32

photoperiodic

Question 33

specific light/dark cycle (in hours) needed for breeding

Answer 33

14 hours light, 10 hours dark

Question 34

optimum temperature in raising Zf

Answer 34

28.5 degrees Celsius

Question 35

differentiate male Zf from female Zf

Answer 35

males: longer, slimmer, more yellow females: plumper and more silvery

Question 36

best food source for high-protein diet of Zf

Answer 36

brine shrimp

Question 37

ratio of males to females in breeding tank

Answer 37

1 male to two females

Question 38

when mating usually occurs

Answer 38

dawn/light period

Question 39

food of Zf when below 10 days old

Answer 39

baby fish food or paramecia

Question 40

enumerate the 2 solutions that can be used to maintain Zf embryos

Answer 40

1. egg water | 2. 10% Hank's stock solution

Question 41

used to anesthetize embryos

Answer 41

tricaine

Question 42

used to dechorionate

Answer 42

dilute pronase

Question 43

ciliated organ of asymmetry in the zebrafish embryo that initiates left-right development of the brain, heart and gut.

Answer 43

Kupffer's vesicle

Question 44

the phylotypic stage in Zf development

Answer 44

pharyngula stage

Question 45

enumerate 3 effects of cold temperature (~18 degrees) on Zf development

Answer 45

inhibits microtubules inhibits ooplasmic segregation? inhibits axis formation?

Question 46

effect of high temperature (~40 degrees) on development

Answer 46

first mitotic division prevented | diploids become tetraploids

Question 47

substance that can cause birth defects (include examples of these)

Answer 47

teratogens (ex. mercury, thalidomide, alcohol, vitamin A)

Question 48

usually prescribed to people with bipolar disorder

Answer 48

lithium carbonate

Question 49

enumerate the 5 teratogenic effects of lithium

Answer 49

1. Ebstein anomaly (heart) 2. spina bifida 3. "floppy infant syndrome" (weak, unresponsive baby) 4. exo-gastrulation (archenteron evaginates instead) 5. dorsalized embryo (recall Wnt/β-catenin pathway)

Question 50

describe the relationship of the following: glycogen synthase kinase (GSK), β-catenin, lithium, inositol triposphate

Answer 50

1. lithium inhibits GSK, which inhibits β-catenin | 2. lithium depletes inositol triphosphate in PIP cycle

Question 51

enumerate the derivatives of vitamin A

Answer 51

1. β-carotene 2. vitamin A/retinol 3. retinal 4. retinoic acid 5. tretinoin 4. isotretinoin

Question 52

enumerate 4 teratogenic effects of retinoic acid

Answer 52

1. microcephaly 2. microphthalmia 3. craniofacial defects 4. cardiovascular defects (ex. teratology of Fallot) 5. thymus defects 6. reduced limbs

Question 53

broken down to retinoic acid when exposed to sunlight

Answer 53

methoprene

Question 54

a posteriorizing signal known to influence Hox gene expression

Answer 54

retinoic acid

Question 55

enumerate 3 teratogenic effects of alcohol

Answer 55

1. fetal alcohol syndrome (face, heart, mental retardation) 2. fetal alcohol effect 3. cyclopia (only 1 eye)

Question 56

enzyme that breaks down alcohol. is this found in embryos?

Answer 56

alcohol dehydrogenase; NOT in embryos

Question 57

enumerate 4 examples of endocrine disruptors

Answer 57

1. dioxin 2. DDT 3. p-nonylphenol 4. phthalates

Question 58

enumerate examples of behaviors that can be observed

Answer 58

1. touch stimulus 2. phototactic/negative phototactic response (towards/away from light) 3. mating behavior 4. dominance hierarchy

Question 59

2 dyes used for whole mounts (include what they stain)

Answer 59

1. alcian blue - stains glycosaminoglycans of cartilage at low pH 2. alizarin red - stains calcium in bones at high pH

Question 60

embryonic primordium determined to form specific organ

Answer 60

anlage

Question 61

exogenous substances that interfere with normal hormone function

Answer 61

endocrine disruptors

Question 62

precursor to pectoral and pelvic fins

Answer 62

fin bud

Question 63

type of egg (in terms of yolk amount)

Answer 63

macrolecithal

Question 64

the segregation of specific informational molecules within the cytoplasm to different regions of egg

Answer 64

ooplasmic segregation

Question 65

neuromeres of hindbrain

Answer 65

rhombomere