Male and female sexes have evolved repeatedly in eukaryotes but the origins of dimorphic sexes and their relationship to mating types in unicellular species are not understood. Volvocine algae include isogamous species such as Chlamydomonas reinhardtii, with two equal-sized mating types, and oogamous multicellular species such as Volvox carteri with sperm-producing males and egg-producing femal...

Sexual reproduction (conjugation) in protozoan ciliates is induced by specific cell-cell interactions between cells of complementary mating types. The ancestral ciliate Blepharisma japonicum has two mating types, I and II. The substances that act as signaling molecules in this extracellular interaction for conjugation are called gamones. The glycoprotein gamone 1, produced by mating type I cell...

Homothallic strains of Saccharomyces cerevisiae can convert mating type from a to alpha or alpha to a as often as every generation, by replacing genetic information specifying one mating type at the expressor locus, MAT, with information specifying the opposite mating type. The cryptic mating type information that is copied and inserted at MAT is contained in either of two loci, HML or HMR. The...

ATING type inheritance in a cililate follows one of two basic patterns (SONNEBORN 1947; BEALE 1954; KIMBALL 1964; NANNEY 1968). In ciliates with genic inheritance mating types are controlled directly by one or more genes. In ciliates with epigenetic inheritance an array of mating type potentialities is controlled by nuclear genes, but which mating type is actually expressed by a given cell is d...

Fungi have evolved a remarkable diversity of reproductive strategies. Some of these, most notably those of the model fungi, have been well studied but others are poorly understood. The latter is also true for uni-directional mating type switching, which has been reported in only five fungal genera, including Ceratocystis. Mating type switching allows a self-fertile fungal isolate to produce bot...

Arthroderma benhamiae is a zoophilic dermatophyte belonging to the Trichophyton mentagrophytes species complex. Here, a population of A. benhamiae wild strains from the same geographical area (Switzerland) was studied by comparing their morphology, assessing their molecular variability using internal transcribed spacer (ITS) and 28S rRNA gene sequencing, and evaluating their interfertility. Seq...

The genus Cercospora consists of numerous important, apparently asexual plant pathogens. We designed degenerate primers from homologous sequences in related species to amplify part of the C. apii, C. apiicola, C. beticola, C. zeae-maydis and C. zeina mating type genes. Chromosome walking was used to determine the full length mating type genes of these species. Primers were developed to amplify ...

Cell type specification is a fundamental process that all cells must carry out to ensure appropriate behaviors in response to environmental stimuli. In fungi, cell identity is critical for defining "sexes" known as mating types and is controlled by components of mating type (MAT) loci. MAT-encoded genes function to define sexes via two distinct paradigms: 1) by controlling transcription of comp...

Yeast cells of mating type alpha excrete a sex factor which inhibits cell division and deoxyribonucleic acid replication but not ribonucleic acid or protein synthesis in cells of opposite mating type a.

A two-locus haploid model of sexual selection is investigated to explore evolution of disassortative and assortative mating preferences based on imprinting. In this model, individuals imprint on a genetically transmitted trait during early ontogeny and choosy females later use those parental images as a criterion of mate choice. It is assumed that the presence or absence of the female preferenc...