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