Schizosaccharomyces pombe

Schizosaccharomyces pombe. It is a species of yeast that is a key model organism in modern cell biology and molecular biology. Commonly known as fission yeast, it is studied for its simple eukaryotic cell structure and conserved biological processes. Its discovery in East Africa and subsequent adoption by researchers like Paul Nurse have made it fundamental to understanding the cell cycle.

Biology and life cycle

The cells of this yeast are rod-shaped and divide via a process known as medial fission, where a septum forms in the middle of the cell. It exhibits a predominantly haploid life cycle, which simplifies genetic analysis. Under conditions of nutrient starvation, haploid cells of opposite mating type can conjugate to form a diploid zygote, which then undergoes meiosis to produce ascospores. This life cycle is regulated by complex signal transduction pathways responding to environmental cues, similar to those found in metazoans.

Research significance

This organism has been instrumental in identifying conserved genes that control the eukaryotic cell cycle. Landmark work by Paul Nurse, using genetic screens in fission yeast, led to the discovery of the key regulator cdc2, the homolog of the CDK1 gene in humans. For this contribution to understanding cell cycle regulation, Nurse shared the 2001 Nobel Prize in Physiology or Medicine with Leland H. Hartwell and Tim Hunt. Its study has also profoundly advanced knowledge of chromosome dynamics, DNA repair mechanisms, and cell polarity.

Genetics and genomics

The genome was fully sequenced and published in 2002 by an international consortium led by the Sanger Institute, revealing approximately 4,940 protein-coding genes on three chromosomes. This made it one of the first higher eukaryotes to have its genome completely sequenced. Its genetic tractability allows for efficient homologous recombination, enabling precise gene knockout and tagging studies. Resources like the PomBase database, curated by the University of Cambridge and the European Bioinformatics Institute, provide comprehensive genetic and molecular information for the research community.

Use as a model organism

It is prized as a model due to its simplicity, ease of genetic manipulation, and evolutionary distance from the other major yeast model, Saccharomyces cerevisiae. It serves as an excellent model for studying fundamental processes such as cytokinesis, chromatin organization, and RNA interference, pathways that are highly conserved in mammals. Research using this yeast has direct implications for understanding human diseases, including cancer and neurodegenerative disorders like Alzheimer's disease. Its cell shape and growth pattern also make it ideal for studies on cell morphology and the cytoskeleton.

History and discovery

The species was first isolated in the 1890s from fermented millet beer in East Africa by German researchers. The name "pombe" is derived from the Swahili word for beer. It was not widely used in laboratory research until the 1950s, when Murdoch Mitchison and others pioneered its study of the cell cycle. The foundational genetic work by Urs Leupold in the mid-20th century established its classical genetics. Its rise to prominence in molecular biology was cemented by the cell cycle research of Paul Nurse and his colleagues in the 1970s and 1980s.

Category:Ascomycota Category:Model organisms Category:Yeasts