Evo Devo

blastomeres retain all genetic info and totipotency until when?

16 cell stage

are ICM cells pluripotent or totipotent?

pluripotent - does not form extraembryonic

important factors for ICM pluripotency

Oct4, Sox2, and Nanog

iPS cells are:

pluripotent: makes most but not all somatic cell types

housekeeping genes

expressed by all/most somatic cell types and provides proteins for basic cell structure and metabolism

tissue-specific genes

determines cell’s phenotype

miRNA

small non-coding RNAs that attach to specific mRNA for translation inhibition or degradation

where is Pax6 found and what is it?

a transcription factor found only in eyes, pancreas, and neural tube - crucial for eye formation

knowing Pax 6 must work with other TFs to activate, which TFs are required?

lens cells: Sox2, Maf, and delta-EF3

pancreas cells: Pbx1, Pdx1, and CREB

how long is chromatin in total?

2 meters

histone ______ increases gene accessibility

which tails?

acetylation of H3 and H4 - neutralizes charge

pioneer transcription factors (+example)

accesses tightly coiled chromatin to initiate local relaxation - pioneers the opening of the region

ex: Pbx1

histone methylation ________ gene accessibility

alters - may either increase or decrease

trimethylation of H3 at lysine 4 - promotes transcription

dimethylation or trimethylation at lysines K9 and K27 - promotes silencing

where does DNA methylation occur?

CpG sequences - catalyzed by Dnmt

DNA methylation in a gene’s promoter ________ transcription

represses

genomic imprinting

refers to the concept that some genes will only be active when located on the maternally or paternally derived chromosome

Igf2 is ______ derived and _______ fetal growth

paternally

promotes

Igf2r is _________ derived and ________ fetal growth

maternally

inhibits

steps of DNA methylation during development

1. DNA methylation is maintained from parental copies

2. DNA methylation is removed

3. DNA methylation initiates

4. DNA methylation is modified

X chromosome inactivation is initiated at the _______ locus and is mediated by ________ (non-coding RNA)

XIC

Xist

X chromosome inactivation involves extensive methylation of H3, H4, and cytosines of the DNA?

True

primordial germ cells are diploid or haploid?

diploid

germ plasm

nuclei in the _______ pole plasm develop into pole cells after 9 divisions

posterior

pole cells become

gametes

produced by gut and repels pole cells

Wunen

secreted by developing gonads as chemotactic factor

Hedgehog

a gcl mutation will result in ______ flies

sterile

pole plasm constituents

nanos - binds 3’ UTR to inhibit certain translation

polar granule component - inhibits RNA poly II

Piwi - acts with microRNAs

Vasa - translation initiation factor

Oskar - anchors other constituents in posterior

PGCs in humans develop in ______ region where TFs _______ and _______ are expressed

posterior

Blimp1

Prdm14

SDF-1

from gonads, attracts PGCs in some vertebrates

pluripotency genes expressed by:

ICM

hESCs

iPS

diapedesis

cells squeeze through walls of other cells - between cells

what does the female gonadal ridge produce to drive oogenesis pathway?

Wnt4 - allows activation of Beta-catenin in nucleus

CYP26B1

degrades retinoic acid

Prophase stages

leptotene

zygotene

pachytene

diplotene

diakinesis

Type A spermatogonium

founder population, perpetually replicating

Sertoli cells release

retinoic acid and GDNF

sperm development stages

spermatogonia - primary spermatocytes - secondary spermatocytes - spermatids - spermatozoa

stage of arrest in oogenesis

diplotene - caused by phosphorylation

amphibians synthesize proteins rapidly following fertilization thanks to rRNA amplification in the ________ stage

pachytene

cortical granules are derived from

Golgi vesicles

ovulation is triggered by

LH surge

Graafian follice

mature primary oocyte

until fertilization, oocytes are arrested in

metaphase II as secondary oocytes

resact and speract

chemotactics of sea urchin eggs

progesterone and CRISP1

cumulus layer chemotactics

Izumo to

Juno (and CD9)

fast block to polyspermy

rapid depolarization (in aquatics)

Slow block to polyspermy

cortical granules release their contents coating the egg - gives swelling and elevation, hardens membrane, and removes bindin receptors

catalyzes slow block hardening:

Udx1 - catalyzes peroxidase activity

zygotic cleavage lacks these two phases of the cell cycle

G1 and G2

blastocoel develops

32 cell stage

blastocoel development gives rise to layer:

ICM and trophoblast (extraembryonic chorion)

Cdx2

blocks pluripotency genes, inactivated by hippo at ICM layer

potency of trophoblast cells

unipotent - placental tissue only

are translation or transcription required for early blastomere cleavage?

translation only - maternal deposits yay

maskin can block translation through binding proteins at which end of mRNA?

both - loopy gal

translation requires 5’ cap

true

main function of gastrulation

form the three primary germ layers

sites of gastrulation:

mouth first

anus first

protostome

deuterostome

where does dorsal lip form?

grey crescent region - just below marginal zone

lines roof of blastocoel during gastrulation

fibronectin fibrils

chordamesoderm

early population of deep marginal zone cells from dorsal lip involution

differences in gastrulation of birds compared to amphibian

starts with delamination instead of involution

ingression at primitive streak

_______ portion of the notochord develops earlier

anterior

ISP2

trypsin-like enzyme secreted by uterine endometrial glands to digest the zona pellucida and hatch the balstocyte

adhesion molecules on blastocyst to attach to endometrium

L-selectin, integrins, and HB-EGF

decidualization

prep for implantation

syncytiotrophoblast

connects to endometrium and secretes proteases

cytotrophoblast

standard outer lining

______ _______ encourage cell specification

growth factors

placenta

chorion and uterine endometrium

early pregnancy factor

produced by trophoblast cells of implanting blastocyst to suppress maternal immune response

human chorionic gonadotropin (HCG)

produced by trophoblast cells of implanting blastocyst - signals corpus luteum to maintain progesterone production

2 male pronuclei

bad embryo, good placental chorion

2 female pronuclei

good embryo, bad placental chorion

specification vs determination

cell fates - reversible vs irreversible

autonomous specification

cytoplasmic determinants

conditional specification relies on

induction between cells

yellow crescent CYTOPLASM in tunicates specifies:

muscle cells - via Macho1 (activates Tbx6 TF)

necessity experiment

removes function

sufficiency experiment

adds function

skn1 in c. elegans

specifies muscle and endoderm - double mutation lacks these

P granules

cytoplasmic determinants - settle in c. elegans posterior via microfilament assistance - specify germ cells

PIE1

transcriptional repressor of somatic differentiation

blastomere potency

multipotent

2 components of induction systems

inducer

“competent” responding tissue - tissues typically lose this over time as they become more specialized

instructive induction

specifies a multipotent responding tissue to a specific fate

permissive induction

induction providing conditions for an already specified tissue to complete its predetermined fate

specification of E fate requires _______ induction

P2

mom-2 mutation

more mesoderm - no intestine as E blastomeres adopt MS fate

mom-2 usually is a Wnt protein in P2 used to induce E fate from EMS

in charge of instructive induction in sea urchins

micromeres

woah wait dorsal lip has inductive properties?

yeah bro for neural ectoderm

genes to set up D/V and A/P axes in drosophila

maternal-effect

A/P axis

gurken/torpedo at posterior - sets up microtubule network

anterior - bicoid - blocks caudal

posterior - nanos - inhibition of hunchback

*in unfertilized egg

torso

promotes development of acron and telson - both extremities

tailless + huckebein + bicoid = acron

tailless + huckebein = telson

D/V axis

gurken/torpedo around dorsal edge of oocyte - inhibits pipe

pipe cascade

pipe - snake - Easter - spatzle - receptor Toll (ventral) - pelle - cactus - dorsal (TF) —— dorsal active in ventral region fantastic

dorsal mutants

do not form ventral tissues