L11 Flashcards
in the xenopus life cycle, there is no _______, or ____ and _____ phase
gap
G1
G2
Xenopus eggs contain a large pool of _______ mRNAs and proteins
maternal
X. during cleavage stages, _______ are synthesized from maternal mRNAs
new proteins
during the first 12 divisions of xenopus, there is very little _______
transcription
X. if you block protein synthesis, what happens?
blastula stops dividing
X. sox17b and hbox18 are examples of what
transcription factors
when placed in a neutral environment, animal cells express _______ genes and vegetal cells express _______ genes. they are specified to these fates
ectodermic
endodermic
ectodermic genes go on to form what
epidermis, CNS, neural crest
endodermic genes go on to form what
internal organs, GIT, respiratory system
all metzoans have _______ germ layers
3
the vegetal pole can ________ cells from the animal pole to become ________
instruct
mesodermic
the _______ have the capacity to become mesodermic
animal cap cells
if you recombine the animal cap with dorsal subsets, the result is mainly _____ genes
dorsal
if you recombine the animal cap with the ventral subset, what happens?
vegetal pole tells them which type of mesoderm to become
what are mesodermic marker genes?
secreted factors that can pass through small pores
prospective ectoderm and endoderm are specified by ________
maternal factors
3 germ layers and what they entail
ectoderm - skin and NS
endoderm - internal organs
mesoderm - kidney, blood, muscle, notocord
characteristics of mesoderm inducers in Xenopus
secreted _________
cells from the _________ form mesoderm if exposed to the inducer
may induce different type of mesoderm along the _________ axis
expressed in the _________ at early blastula stage
proteins
animal cap
D/V
vegetal pole
Vg1 is a member of the _____ superfamily of growth factors. its RNA is expressed early during _______ and is localized at the ________ of the oocyte
TFGbeta
oogenesis
vegetal cortex
knock-down only reduces _________
mesoderm induction
Vg1 is only expressed in the _______ side of the embryo
dorsal
egT is an _______ factor - it is not secreted
intrinsic
VegT is a ___________ factor, which is _____ expressed in all the ________ half of the embryo
transcription
maternally
vegetal
maternal VegT induces _______ expression of ______ ligands - they are called Xnrs in xenopus
zygotic
nodal
nodal goes from _____ to ______ from ventral to dorsal
low
high
the ______ form of smad2 is the active form of smad2
phosphorylated
Nodal signalling is active at the right stage for ___________ induction
mesoderm
TGFbeta is expressed in a lot of what
cancer
SB505124 and SU5402 are what
an ATP analog
inhibitin Nodal signalling causes loss of ________ is Xenopus embryo
mesoderm
nodal signalling is required for ____________ gene expression
endodermic
what are some roles of FGF signalling in mesoderm specification?
docking site for FH2 containing proteins
MAP kinase pathway
signals receptors that are tyrosine kinases
the MAP kinase pathway is activated in the _________ during __________
marginal zone
gastrulation
nodal induces ______ in the cells overlying the ______
mesoderm
endoderm
the Spemann’s organizer has ______ and ______ inhibitors
BMP
wnts
the roles of the spemann’s organizer during development are as follows:
- limit _____ signalds in the mesoderm
- inhibit ____ signalling in the _____ to induce the neuro-ectoderm
- contribute to _______ mesoderm
verntral
BMP
ectoderm
axial
the Spemann organizer is a _________ structure situated above the _________ in the ______ stage of amphibian embryos
multicellular
blastopore lip
gastrula
the spemann organizer secretes ___________ and ________ inhibitors
canonical Wnt
BMP
when transplanted to the opposite site of an embryo, the spemann organizer can induce an ___________ neural plate and a _____ axis
ectopic
secondary
the Nieuwkoop centre and the Spemann organizer both give rise to _______ axis when grafted in the ____ side
secondary
ventral
the ectoderm and endoderm are ______ specified, but the mesoderm is induced post _______
maternally
MBT
the __________ induces the formation of the Spemann organizer
Nieuwkoop centre
the spemann organizer limits ventral signals in the _______ and is necessary for the induction of ___________
mesoderm
neural fate
