Polarity and Cell Fate

959

there are always — somatic cells in the c. elegans

p-granules

— are cytoplasmic determinants that are formed from ribonucleoprotein complexes that specify the germ cells

P4

in c. elegans, the — cell inherits most of the p-granules in asymmetric division. this cell gives rise to the germline. The inherited determinants help direct the cell toward a germline fate rather than a somatic (body-cell) fate.

p-granules

in c. elegans, the P4 cell inherits most of the — in asymmetric division. this cell gives rise to the germline. The inherited determinants help direct the cell toward a germline fate rather than a somatic (body-cell) fate.

asymmetric

early divisions in c. elegans development are (symmetric/asymmetric)

bag of worms

In C. elegans, the “—” phenotype was famously used to identify maternal-effect lethal (mel) mutations that affect early embryonic development, including genes involved in asymmetric cell division.

Par

in c. elegans, — genes are required for early asymmetry

diffuse, asymmetry

before fertilization, Par protein are — through the oocyte.

after fertilization, — is enforced

sperm asters

the — destabilizes PAR-3/6 in the posterior to establish the initial gradient

PAR-3/6

the sperm asters destabilizes — in the — to establish the initial gradient

anterior

at the —, PAR-3/6 destabilizes PAR-2

PAR-3/6

at the anterior, — destabilizes PAR-2

PAR-2

at the anterior, PAR-3/6 destabilizes —

sperm asters, PAR-2

— and — destabilize PAR3-3/6

PAR-2

— stabilizes PAR-1

stabilizes

PAR-2 (stabilizes/destabilizes) PAR-1

low

where PAR-3/6 is high, PAR-2 and PAR-1 are —

high, low

at the anterior, PAR-3/6 is —, and PAR-2 and PAR-1 are —

low, high

at the posterior, PAR-3/6 is —, and PAR-2 and PAR-1 are —

before

the PAR gradient is established (before/after) the pronuclei have fused

MEX-5/6

PAR-1 phosphorylates and destabilizes —

destabilizes

PAR-1 phosphorylates and (stabilizes/destabilizes) MEX-5/6

PAR-1

— phosphorylates and destabilizes MEX-5/6

low

where PAR-1 is high, MEX-5/6 is —

anterior

MEX-5/6 is high in the — end

MEX-5/6

— destabilize the germline proteins like PIE-1 and other components of the P-granules

high

where PAR-1 is high, germline proteins like PIE-1 are —

low

where MEX-5/6 is high, germline proteins like PIE-1 are —

posterior

PIE-1 and p-granules are high in the — end

MEX-5/6, germline proteins

by the time the cell divides, — and — are in a gradient

mitotic spindle, PAR

The first cleavage is asymmetric, caused by asymmetric positioning of the —, which is influenced by —. The cleavage furrow forms off-center, producing a larger anterior daughter, AB, and a smaller posterior daughter, P1.

AB, P1

The first cleavage becomes asymmetric. The cleavage furrow forms off-center, producing a larger anterior daughter, —, and a smaller posterior daughter, —.

the par proteins have a — role in generating and maintaining polarity in cells

basal

in epithelial cells, PAR-1 is enriched in the — side

apical

in epithelial cells, PAR-3, PAR-6, and aPKC are enriched in the — side

yes

can P1 develop all lineages correctly without AB?

no

can AB develop all lineages correctly without P1?

mesodermal pharynx

without P1, we can’t form the —

conditionally

We can’t develop the mesodermal pharynx without the P1 cell, so it is clear that the mesodermal pharynx cell is — specified

skn-1

when the — gene is deleted, the gut and mesodermal pharynx cannot develop. this means that this maternal effect gene is required for normal development of these tissues

skn-1

the EMS gives rise to C-type daughters in — mutant embryos

epidermis, muscle

the EMS gives rise to C-type daughters in skn-1 mutant embryos, which give rise to — and —

PIE-1

— is a transcription factor present only in P2 and blocks the activity of SKN-1

SKN-1

PIE-1 is a transcription factor present only in P2 and blocks the activity of —

P2

the PIE-1 gene is present in. all cells, but it is only expressed in — cells

PIE-1

SKN-1 normally causes the EMS fate, but — blocks it and causes the P2 fate

SKN-1

EMS cell is able to develop and derive its fate based on the presence of —

conditionally specified

We can’t develop the mesodermal pharynx without the P1 cell, so it is clear that the mesodermal pharynx cell is —