Ectopic expression of a Chlamydomonas mt+-specific homeodomain protein in mt- gametes initiates zygote development without gamete fusion

Citation
H. Zhao et al., Ectopic expression of a Chlamydomonas mt+-specific homeodomain protein in mt- gametes initiates zygote development without gamete fusion, GENE DEV, 15(20), 2001, pp. 2767-2777
Citations number
46
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Cell & Developmental Biology
Journal title
GENES & DEVELOPMENT
ISSN journal
0890-9369 → ACNP
Volume
15
Issue
20
Year of publication
2001
Pages
2767 - 2777
Database
ISI
SICI code
0890-9369(20011015)15:20<2767:EEOACM>2.0.ZU;2-B
Abstract
The molecular mechanisms that activate expression of zygote genes after fer tilization are obscure. In animals, receptor-ligand interactions during spe rm-egg membrane fusion as well as delivery of putative regulatory molecules by the sperm into the egg cytoplasm are proposed to activate zygote develo pment and subsequent transcription of zygote genes. The mechanisms of activ ation of zygote development in higher plants also are mysterious, in part b ecause of the difficulty of isolating female gametes of higher plants. In t he unicellular, biflagellated green alga Chlamydomonas, the early steps in zygote development are much more accessible to investigation. Within minute s after mating type plus (mt+) and mating type minus (mt-) gametes fuse, ex pression of several zygote-specific transcripts is induced independently of protein synthesis. Here, we show that ectopic expression in mt- gametes of an mt+ gamete-specific, homeodomain protein, GSP1, induces a zygote-like p henotype and activates expression of zygote genes. One of the genes, zsp2, expressed in these "haploid zygotes" encodes a zygote cell surface adhesion molecule that promotes formation of multicellular aggregates. In total, ex pression of six out of seven zygote genes examined was induced by ectopic e xpression of GSP1. Our experiments show that in addition to contributing th eir genomes to the zygote cytoplasm, gametes also deliver proteins that can activate gene transcription.