Final noon Thursday May 5
description
Transcript of Final noon Thursday May 5
Final
noon Thursday May 5
I will post answers for any remaining questions emailed to me by noon on Tuesday May 3
Imprinting results from pre-programmeddifferences in DNA methylation of selected genes in the sperm and egg
Imprinted genes affect fetal growth
Insulin growth factor 2 Insulin growth factor 2 (Igf2) receptor (Igf2r)
growth growth
What happens if dad’s copy of Igf2 is deleted?
Insulin growth factor 2 Insulin growth factor 2 (Igf2) receptor (Igf2r)
growth growth
What happens if mom’s copy of Igf2 isn’t imprinted?
Insulin growth factor 2 Insulin growth factor 2 (Igf2) receptor (Igf2r)
overgrowth growth
Beckwith-Weidemann syndrome
What if mom’s copy of Igf2r is deleted?
Insulin growth factor 2 Insulin growth factor 2 (Igf2) receptor (Igf2r)
overgrowth growth
T F A mouse that inherits a mutant maternal copy of Igf2 exhibits fetal undergrowth.
T F A mouse that inherits a mutant Igf2r gene from its mother is born 40% smaller than normal.
T F Maternal imprinting of the human Igf2r gene prevents fetal overgrowth.
T F Maternal imprinting of the human Igf2 gene prevents fetal overgrowth.
T F Mutations in the paternal copy of the mouse Igf2 gene cause mice to be born 40% smaller than normal.
Chromatin transferred from myoblasts can transform untreated fat cells.
Experiment #2
Transformation frequency suggests only one or few of the genes have this ability
C3H/10T cells = fibroblast cells (make connective tissue, synthesize the extracellular matrix and collagen)
If treated with azacytadine, C3H/10T cells can be induced to form muscle, fat and cartilage cells.
Ultimately a single gene was identified-myoD
-whose expression could convertany other cell type into muscle cells
Getting the terminology down: C. elegans Vulva
Figure 6.27Anchor cell (AC) Gonad
VPCs
Early larval stage
P3.p-P8.p are the Vulva Precursor Cells (VPCs)
AC Basement membrane
Gonad
Later larval stage
P5.p,P6.p and P7.p lineages make the vulva
P3.p,P4.p and P8.p lineages non-vulval
1° 2°2° 3°3°P6.p P7.pP5.pP3.p P4.p P8.p
3°
The Ras pathway is abnormally activated in many human tumors
eg: pancreatic cancer, colorectal cancer, lung adenocarcinoma, gall bladder cancer, bile duct cancer and thyroid cancer
signal
(VPC cells)
LIN-3
Another representation of the RAS pathway
Inductive and lateral signals induce the vulva
gonadAnchor cell
VPCsP3 P4 P5 P6 P7 P8
VPCs after induction 1° 3°3° 3° 2°2°
The primary and secondary cells form the vulva
A signal from P6.p actives notch (lin-12) in P5.p and P7.p
Figure 6.27
Both membrane and receptor are membrane bound!
The transmembrane receptor is the Lin-12 protein, a receptor protein related to Notch
“ Primary cell”
“ Secondary cells”
Generation of Different Cell Types From Equivalent Cells in C. elegans: Initial specification of the Anchor Cell also requires Notch
Figure 6.28
The signal:lag-2 (delta)
The receptor: lin-12 (notch)
gonad
anchorcell
3° cell3° cell 3° cell
If anchor cell signaling is disrupted, all VPCs cells adopt a non-vulva fate
3° cell 3° cell3° cell
no vulva