Ciclo De Vida De Levaduras

MICROBIOLOGICAL REVIEWS, Dec. 1988, p. 536-553

Vol. 52, No. 4

0146-0749/88/04536-18$02.00/0

Copyright C 1988, American Society for Microbiology

Life Cycle of the Budding Yeast Saccharomyces cerevisiae
Department

of Biochemistry

IRA HERSKOWITZ
& Biophysics, University of California, San Francisco, San Francisco, California 94143

INTRODUCTION....................................................................
PROLIFERATION: THE MITOTIC CELL CYCLE

....................................................................

TRANSITIONS: MATING AND SPORULATION ....................................................................

536

537
538

538
Specialized Cell Types ....................................................................
Cell Specialization:Explicit Programming and Environmental Response ........................................ 539
cells ....................................................................
a

539

cells ....................................................................

540

a/a cells ....................................................................
Initiation of

Sporulation....................................................................
Assaying Mating and Sporulation ....................................................................
Mating ....................................................................
Sporulation ....................................................................

540
541
541
541

542

HOMOTHALLISM AND HETEROTHALLISM: MATING-TYPE INTERCONVERSION................... 542
542
Mating-Type Interconversion ....................................................................
Genetic Rearrangement by Cassette Transposition .................................................................... 543
Biological Significance of Mating-Type Interconversion and Pattern of Switching ............................. 544

VARIATIONS ON THE S. CEREVISIAE LIFECYCLE: DIFFERENT TYPES OF
HETEROTHALLISM ....................................................................

545

A THEORETICAL DISCUSSION OF HOMOTHALLISM: ARE OTHER MECHANISMS POSSIBLE?.546
LIFE CYCLES OF SOME OTHER ORGANISMS ...................................................................

547

547
Schizosaccharomyces pombe....................................................................
Neurospora crassa and Other Filamentous Ascomycetes .............................................................. 548
548
Basidiomycetes ....................................................................
Ciliates and Algae ...................................................................
548

CONCLUDING COMMENTS AND MAJOR CONCLUSIONS.......................................................549
ACKNOWLEDGMENTS ...................................................................

549

LITERATURE CITED ....................................................................

549

INTRODUCTION

processes, mating (which involves cell
are fundamental biological processes

fusion) and meiosis,
and also occur in
multicellular organisms. The life cycle of S.cerevisiae has an
additional aspect beyond proliferation, mating, and meiosis:
haploid yeast cells can change their cellular type by a
programmed deoxyribonucleic acid (DNA) rearrangement.
This allows some S. cerevisiae strains to exhibit a homothallic life cycle (a life cycle in which a single haploid cell can
give rise to diploid cells capable of meiosis and spore
formation). Other strains of S.cerevisiae exhibit a heterothallic life cycle (a life cycle in which a single haploid cell is
unable to produce diploid cells) (discussed in the section,
"Homothallism and Heterothallism: Mating-Type Interconversion"). Understanding the homothallic and heterothallic
life cycles is important for understanding many organisms
(including filamentous fungi) and raises issues concerning
how...