[LE2] Lecture 8 Flashcards by Genella Alessandra Roallos

(A) Phylogenetic tree of the chordates showing the relationship of the vertebrate groups. The embryonic development of fish and amphibians must be carried out in _______ environments.

moist

How well did you know this?

Not at all

Perfectly

_____ is the only vertebrae that is not a tetrapod. All other animals are tetrapods including birds, reptiles, mammals, amphibians

Fish

How well did you know this?

Not at all

Perfectly

Some other mammals are also __________ - The only thing that separates fish is they have fins, whereas all other groups of vertebrae have jointed limbs

aquatic

How well did you know this?

Not at all

Perfectly

Typical __________ development (bony fish)

Why this organism?
- ________ development

teleost
rapid

How well did you know this?

Not at all

Perfectly

Easy to obtain ________ number of embryos
________ fertilization

large
external

How well did you know this?

Not at all

Perfectly

Clear embryos
Can perform _________ screens - can mate mutants, develop lineages that contain a mutation

genetic

How well did you know this?

Not at all

Perfectly

The male parent is _____________ and mated with a wild-type (+/+) female. If some of the male’s sperm carry a recessive mutant allele (m), then some of the F1 progeny of the mating will inherit that allele. F1 individuals (here shown as a male carrying the mutant allele m) are then mated with wild-type partners. This creates an F2 generation wherein some males and some females carry the recessive mutant allele. When the F2 fish are mated, approximately 25% of their progeny will show the mutant phenotype

mutagenized

How well did you know this?

Not at all

Perfectly

EARLY ZEBRAFISH DEVELOPMENT
CLEAVAGE:

Eggs are _____________
The only portion of the egg that cleaves is a thin yolk-free region of cytoplasm called
the ____________ located in the animal pole

telolecithal
blastodisc

How well did you know this?

Not at all

Perfectly

First divisions highly ___________, ___________, ________ (every 5 minutes)
○ Form a mound of cells at the animal pole called the ___________
○ Large yolk cell remains underneath

reproducible, synchronous, rapid
blastoderm

How well did you know this?

Not at all

Perfectly

They don’t cleave the entire yolk, the only part that would develop is the ______________

top of yolk

How well did you know this?

Not at all

Perfectly

Generates the fish organizer, patterning the mesoderrm, and leading the epiboly of ectoderm

Yolk syncytial layer (YSL)

How well did you know this?

Not at all

Perfectly

Made up of the superficial cells from the blastoderm, forming an epithelial sheet of single cell layer think

Enveloping layer (EVL)

How well did you know this?

Not at all

Perfectly

Sloughed off after 2 weeks
Allows the embryo to develop in a _________ solution

hypotonic

How well did you know this?

Not at all

Perfectly

Give rise to embryo proper

Deep cells

How well did you know this?

Not at all

Perfectly

Endoderm is the bottom or _________ pole.

Mesoderm is the middle, and ectoderm is the top or _________ pole.

vegetal
animal

How well did you know this?

Not at all

Perfectly

All three layers of the zebrafish undergo _________

epiboly

(this is the difference of zebrafish from the amphibians)

How well did you know this?

Not at all

Perfectly

Epiboly of the ____________ cells over the yolk. Controlled by maternal proteins
(_____________) and proteins transcribed by the YSL

blastoderm, eomesodermin

How well did you know this?

Not at all

Perfectly

Intercalation of the deeper blastula cells of the epiblast into the superficial layers forces it to spread _________

radially

How well did you know this?

Not at all

Perfectly

The ____________ layer separates the developing embryo and the enveloping layer
In ________, the dark green in edges will go down and cover the lighter green

yolk syncytial
epiboly

How well did you know this?

Not at all

Perfectly

The genetic transcription of zygotic genes are still not much, so majority of proteins are from the mother (_______________)
But proteins are starting to be __________ at the yolk syncytial layer

eomesodermin
transcribed

How well did you know this?

Not at all

Perfectly

Important to have your ________ so it can be used for movement and during epiboly progression

actin

How well did you know this?

Not at all

Perfectly

Actin will also be your _____________ or _____________ that will be used to anchor the different cells

microtubule or microfilament

How well did you know this?

Not at all

Perfectly

Cell movements during zebrafish gastrulation:

(A) The blastoderm at 30% completion of epiboly (~4.2 hours).
(B) Formation of the hypoblast, either by _____________ of cells at the margin of the epibolizing blastoderm or by ____________ and ______________ of cells from the epiblast (~6 hr). A close-up of the marginal region is at the right.
(C) As ectodermal epiboly nears completion, the hypoblast, carrying the mesoderm and endoderm precursors, begins to cover the ______________ (~9 hr).
(D) Completion of gastrulation (~10.3 hr). The _______________ (yellow endoderm, blue ectoderm, red mesoderm) are present.

involution, delamination, ingresion
yolk
germ layers

How well did you know this?

Not at all

Perfectly

The edge of the cells undergoing epiboly thickens to form the ___________

germ ring

How well did you know this?

Not at all

Perfectly

At this point, a population of cells begins to __________ to form a second layer of cells ○ The deep cells that don't migrate - ___________ ○ The migratory cells - _________ These cells move by either ___________ or _______________

migrate epiblast hypoblast involution/ingression

- At a certain time, the deep cells would envolute - There will be an epiblast and hypoblast in the ____________ level - This will be corresponding to the _______________, once cell involute at the are of dorsal blastoporal lip, you will have the endoderm, mesoderm, ectoderm, and the archenteron.

blastocoel archenteron

(A) During epiboly, cells at the border undergo structural changes and ____________. As they do, mesodermal genes (red) are activated. (B) When the cortical cytoskeleton is prevented from contracting, the animal cap cells remain ______________ and do not involute. (C) However, if these cells are pulled by a magnetic field, the _______________ genes become expressed. (D,E) Circumpolar views of B and C, respectively, visualize expression of the mesodermal gene no tail (the zebrafish homologue of the brachyury gene). (D) no tail expression is blocked by the lack of involution. (E) no tail _____________ induced by stretching and subsequent involution.

involute ectodermal mesodermal expression

- In other animals, mesoderm is induced by chemicals, - but in the mesoderm formation of the fishes, it needs ___________ and ___________ of fish - So when movement of epiblast did not occur to move downward, then mesoderm does not form - but with a targeting drug, there will be magnetic force to allow your mesoderm to proceed inward and form

stretching and physical forces

On the dorsal side of the embryo, the hypoblast and epiblast intercalates to form a thickening called the _______________

embryonic shield (same function as the dorsal lip)

Hypoblast will become the __________ + ____________

mesoderm + endoderm (The hypoblast, similar to amphibians, will be forming the lower areas which are the mesoderm and endoderm)

The first cells to become hypoblast will become the ______________

notochord (chordamesoderm) -more anterior side

Cells that flank this on either side become ________________

paraxial mesoderm (somites)

Formed by the concomitant convergence and extension in the epiblast that brings presumptive neural cells into the dorsal midline

THE NEURAL KEEL

Eventually develops a ____________ forming the neural tubes

slitlike lumen

- In amphibians: neural plate -> neural fold -> neural tube - But here, instead of a tube, there is an aggregation of cells, then cells will form a rod and then the lumen will form via the ________________

secondary neurulation

There are 2 types of Neurulation: - The first is the one in amphibians, forming the ____________, ___________, ____________, ___________ - And the other is the ______________, it is where the aggregation of cells occur (the neural keel). Then the lumen opens in the middle (yung nasa third step ng picture na line sa gitna) to form the cavity

neural plate, neural fold, neural tube, then brain vesicles secondary neurulation

AXIS FORMATION IN ZEBRAFISH:

Dorsal, ventral, anterior, posterior, left, right

Critical in establishing the D-V axis - forms the prechordal plate (1st to involute) and notochord

Embryonic shield

- Can convert lateral and ventral mesoderm to become ________ mesoderm - Can cause ectoderm to become ________ rather than epidermal

dorsal neural

- (A) They did experiment on embryonic shield - they transplanted the embryonic shield to the ventral area - they were able to form a secondary axis, where you will have ______________

2 notochords

- _____________ inhibits the lefty and nodal - Lefty also inhibits nodal - Nodal is ______________, it would allow endoderm and mesoderm and fibroblastic growth factor leading to mesodemal form - _________ inhibits BMP

miR430 self-regulating chordin

_______ converts or allow the ectoderm to become epidermis (default of ectoderm is the neural plate w/o presence of BMP)

BMP with bmp = may epidermis no bmp = neural plate

Chordin and lefty are found more dorsal, BMP and nodal found in more _______ side

ventral

NODAL (DORSAL) AND BMP (VENTRAL) GRADIENT - (A) If nodal to BMP is added into another area, if you add another shield, you will be having __________ - (B) The _______ will form similarly, same side sila - (C) Nodal is dorsal and BMP is ventral but if you move them, nodal muna sa _________ and then BMP yung nasa __________ - (D) The tail will form __________ the normal axis - (E) but if you have nodal and BMP opposite the dorsoventral axis - (F) tail will from __________ but in opposite direction

2 axes tail taas, baba against parallel

- (A) you can see the endo, meso, and ectoderm in the animal cap - There is also the yolk cell that generates the _________ signals - (B) BMP - are needed to form _____________ - The ___________ that is part of the organizer will be secreting factors that form the homologue. - For example, chordino will become chordin

mesodermal ectodermal epidermis embryonic shield

FISH SIGNALS ARE LIKE _____________

AMPHIBIANS

Induce formation of the epidermis

BMPs

Found in the ventral and lateral regions of the embryos

Wnt (especially Wnt8) Wnt inhibitor needed for head formation

_____________ secretes factors (homologues of chordin, noggin, and follistatin) that blocks ventral induction › neural development

Notochord

____ in the dorsal region inhibits BMP; _____ is predominant caudal neural specifier

FGFs

______ has a role in the anterior neural plate (upregulation of chordin and goosecoid while restricting bmp2b

IGFs

____________ activates organizer genes in the zebrafish. (B) all will be induced from your ___________, which are localized in the dorsal but will not be localized in the ventral area of the embryo

beta-catenin

Induces formation of head structures

Dorsal blastopore lip (embryonic shield)

Tail organizer

Ventral blastopore lip

Induce trunk and posterior head structures having notochord tissue

Lateral blastopore lips

[A-P AXIS FORMATION] Wnt signal represses the expression of __________ genes _______________, an enzyme that degrades RA in the anterior region

anterior Retinoic acid-4-hydroxylase

Wnts, retinoic acid, and FGFs are required to activate the ___________ genes FGFs and Wnts inhibit the expression of the _________ gene (RA-4H), as well as inhibiting the expression of the head-specifying gene Otx2

posterior cyp26

Wnt and the retinoic acid are located more on the _________ side

posterior

L-R AXIS FORMATION: (B) the _______________ found in the tail area - Yung paikot na color blue is ciliary movement - In other animals it has ______________ motion, but with fish they have ____________

Kupffer's vesicle clockwise counter-clockwise

early cleavage: _____ late cleavage: _____ early gastrula: _____ late gastrula: _____ pharyngula: _____

early cleavage: discoidal meroblastic cleavage late cleavage: yolk synctial layer early gastrula: embryonic shield late gastrula: correct arrangement of 3 germ layers pharyngula: characteristic vertebrate

Late cleavage - The ___________ center is the yolk syncytial layer - Initiates the formation of blastopore of fish which is the ________________

nieuwkoop embryonic shield

Embryonic shield aka ________________

Spemann Mangold Organizer

In late gastrula, all germ layers will undergo __________ - There will be epidermis, neural ectoderm, forebrain midbrain hindbrain, kupffer's vesicle, prechordal plate, notochord

Epiboly

Pharyngula - following the __________ development

Von Baer's

[LE2] Lecture 8 Flashcards

(64 cards)