Genetic Development Presentation

8/3/2019 Genetic Development Presentation

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THE DROSOPHILA PUMILIO GENEENCODE TWO FUNCTIONAL

PROTEIN ISOFORMS THAT PLAY

MULTIPLE ROLE IN GERMLINEDEVELOPMENT, GONADOGENESIS,OOGENESIS AND EMBRYOGENESIS


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The pumilio (pum) play an essential role inembryonic patterning and germline stem cellmaintainance during oogenesis in Drosophila

Germline is a unique cell lineage in which a smallnumber of diploid precursor cell undergo drastic

proliferation and differentation to producenumerous haploid gametes


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During early oogenesis, pum interact with anotherprecursor group gene, nanos (nos), to supress

the translation of maternally loaded hunchback(hb) transcription factor in the posterior region

Pum appears to regulate the proper asymmetricdivision and maintance the GSC during

oogenesis


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Pum protein is present in GSC at higherconc. Than the cytoblast; various pummutation affect either the mitotic ability

or the depletion of germline duringoogenesis

Pum encodes at least 2 major funct.

protein isoforms 156-kD and a novel136-kD isoforms


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DROSOPHILA STRAIN ANDCULTURE

HISTOCHEMISTRY ANDIMMUNOFLUORENSCENCE

MICROSCOPY

NUCLEIC ACIDMANIPULATION


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RESCUE OF PUMNUTANT

DEFECTS BYPUMCDNA

GERMLINECLONAL

ANALYSIS BYFRT-MEDIATED

RECOMBINATION

MRNA IN SITUHYBRIDIZATION


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WESTERNBLOTTINGANALYSIS


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1) Pum is required for premodial germ celldevelopment before oogenesis

If mutation of pum occur, germline stemcell maintenance during oogenesis will fail

Pum ovt mutants

Fail to produce any eggs

Oogenic defects

Ovary size increase Somatis cells number increase


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2. Pum ovt mutants defective in cyst formation and

oocyte differentation

Defective in oogenesis, but not in ovarioleformation

Contain few nurse cells but no oocytes becauseof reduced division of cytoblast.

3. Pum is directly involved in germline stem cell

division Mutants produced ovariole that contain only 1-3

mature egg chambers but no other germ cells.


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4. Pum 1688 partially compliment otherPum ovt and maternal effect pum alleles

Mutation effects more than maternal

effects mutation yet not complementaryaffect embryonic development.

Show maternal effect mutations arestronger mutations

Complimentation of Pum 1688 produceviable yet steril progeny


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Pum involve in premordial germcell proliferation ovary formation,oogenesis and oviposition

Pum does not simply promote orsupress the mitotic ability of

premodial germ cells Pum required for the growth of

premodial germ cell


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Pum is directly required forgermline stem cell divisions

Pum required for cell maintaining

during oogenesis.

Pum also required for the

differentation or symmetry ofgermline stem cell division


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The 130-kD protein functionalproduct of pum gene

o130-kD isoform required for

germline development & oogenesisin a way similar to that 156-kD

o156-kD and 130-kD proteins

possess similar rather thancomplementary functions


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156-kD & 130-kD pum isoformsposses similar function required forgermline development & oogenesis

that can be compensated for thedosage-dependant manner

Pum continuosly required ingermline stem cell division andgermline cyst formation duringoogenesis


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Either 156-kD or 130-kDisoforms is sufficient for matenal

effect function of pum duringembryogenesis


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1. The zygotic formation of pum in preoogenicgermline development and oogenesis mayrequire a high dosage of pum expression thanthe maternal effect function duringembryogenesis

2. The maternal loading of both 156-kD and 130-kD pum isoforms into the embryo may be

abundant so that either isoforms alone cansupport embrygenesis by providing sufficientdose of pum activity.


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3. The difference between the zygotic and maternal

effects may result from the combination of bothmechanisms

Role of pum in zygotic germline development differsffrom its maternal effect role in embryonic

patterning, where its control the translation of onlythe hunchback mRNA.

I. Pum gene- required for embryonic patterning andgermline stem cell division during oogenesis

II. Pum func.- primodial germ cell proliferation, ovaryformation, oogenesis & ovi-position

III. Pum encodes- functional pum isoforms required fordevelopmental processes

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Genetic Development Presentation