Exam 1: Chapter 2 Flashcards
Homeobox
Region of DNA that codes for domain which can bind DNA
Homeobox domain
Codes for homeodomain of protein
Homeodomain
Conserved region of protein
Hox
Family of homeobox genes; conserved in animals
patterns, function as transcription factors
Anterior-Posterior (AP) Patterning
Differentiation of body parts
Prosencephalon
Telencephalon
Diencephalon-thalamus’
Mescencephalon
midbrain
Rhombencephalon
Met- pons/cerebellum
Mey- medulla
Drosophila egg
15 nerve cells, establish radius of mRNA
Drosophilia egg anterior
Bicoid and Hunchback
Drosophilia egg posterior
Nanos and Caudal
____ control expression of pair rule genes
Gap genes
Homeosis
transform 1 gene to another
Ultrabithorax
2 sets of wings
3rd thoracic segment
Antennapodia
transforms antenna to leg
___ sets up for homeotic genes and morphological changes in different segments
pair rule
Goal of homeotic genes
segmenting
Hox genes code for
homeodomain
Ant-C and CT-X in drosophila
homeotic genes in 2 complexes
Why are hox genes on multiple chromosomes?
Pseudo-backups
Homeotic genes into 2 complexes and expressed ___ –> ___ A–> P
3’ to 5’
Linear position on gene matches spatial expression in embryo
KO hox genes in mammals
loss of AP identity
Hindbrain
7 distinct rhomobomeres controlled by hox genes.
KO Hox A1
no abducens nerve
What controls hox expression?
Drosophila: transcriptional regulators set up regions of hox expression (gap genes)
4 factors control hox
RA, Pbx/exd, Hox genes themselves, and fourth on Krox20 we don’t talk about
Specificity of Hox genes for DNA binding increased by
pbx/meis
pbx/meis pair up with
hox genes/homeodomain proteins
help hox genes activate/suppress to get morphologically correct area
KO pbx and meis
don’t get hox genes working
Expressed in right place, but can’t find target
KO pbx, giant r1
Retinoic Acid
binds to receptors in cytoplasm
POSTERIOR
blocks anterior
interacts with RARE regulate Hox
RA= hindbrain
What makes RA
mesoderm. Notochord sets up gradients
Nieuwkoop put small pieces of ectodermal tissue on AP axis and on caudal neural place
AP axis- anterior
Caudal neural plate- posterior
Activator/Anterior/Neural: NCF
Transformer/Posterior: RA, Wnt, FGF
A vs. P what is generally default
neural/anterior
Neural inducers
NCF
Anterior inducers
and what else are they?
Dkk, FrzB, Cerberus (activate NCF, inhibit BMP)
also wnt inhibitors
Transformers
Wnt, RA, FGF, Bumblebee
What happens if you have truncated BMP?
pseudo-wired 2nd head
FGF
neural inducer and posterior genes in animal cap with BMP neural induction
KO FGF8
lose cerebellum
KO Wnt or engrail
lose midbrain
Otx2
forebrain/midbrain ANTERIOR
Gbx2
mid/hindbrain POSTERIOR
___ genes create otx2/gbx2 border
Iroquois genes
lose otx
ancephally, no brain
no r3 in mice
gbx delete
no hindbrain
Engrail (En1)
midbrain/hindbrain border
Alvarado-Mallart’s chicks and quail
2x what you copy UNLESS put in another region.
Met in forebrain? Cerebellum AND Mes. Controls border function
Met: cerebellum
Mes midbrain
Crossley: coated bead with FGF8 on anterior neural tube
repattern anterior –> midbrain/hindbrain
FGF8 organizes mid/hindbrain
FGF8 important for
forebrain
Drosophila Gap genes/vertebrate homologs
Orthodenticle: neuromere 1
(homolog: otx1/2)
Empty spiracles: neuromere 2/3
(homolog: emx1 (A) /2 (P))
Drosophila pair rule gene vertebrate homolog
pax genes
Drosophila segment polarity genes
Engrailed
Homolog V: en1/2
Wingless
Homolog: wnt1
Pax genes are ____ genes with second ___ sequences
homeodomain gnees
pair box
Pax 2 mutation
colobomas (hole in eye)
No pax 2
ectopic stalk
Pax 6 mutation
Partial no iris
complete no eyes
shh KO
exencephaly brain outside skull,
holoprosencephaly- don’t get two hemispheres
Holfreter: notochord, put new notochord by isolated dorsal
second floor plate/ventral portion appears
Nussien-Volhard and Weischaus
Shh expressed in notochord, ventral
Isolate I region
default? dorsal genes
Add shh? Ventral genes
Hindbrain boarder
wnt/FGF
What is the most dorsal derivative of NT provides signals for dorsal differentiation
Neural crest
Wnt or BMP added to neural plate
neural crest development
BMP/Wnt are
Pro-dorsal (and posterior)
What sets up rostral-lateral pole (front/motor)
Pax 6
What sets us caudal medial pole (visual)
Emx2
FGFs
anterior telencephalon