Social amoebae mating types do not invest unequally in sexual offspring

The genetics of sex determination remain mysterious in many organisms, including some that are otherwise well studied. Here we report the discovery and analysis of the mating-type locus of the model organism Dictyostelium discoideum. Three forms of a single genetic locus specify this species' three mating types: two versions of the locus are entirely different in sequence, and the third resembles a composite of the other two. Single, unrelated genes are sufficient to determine two of the mating types, whereas homologs of both these genes are required in the composite type. The key genes encode polypeptides that possess no recognizable similarity to established protein families. Sex determination in the social amoebae thus appears to use regulators that are unrelated to any others currently known.

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Triparental inheritance in Dictyostelium

10.1101/385708 ◽

2018 ◽

Author(s):

Gareth Bloomfield ◽

Peggy Paschke ◽

Marina Okamoto ◽

Tim J. Stevens ◽

Hideko Urushihara

Keyword(s):

Mitochondrial Genome ◽

Dictyostelium Discoideum ◽

High Frequency ◽

Genetic Material ◽

Lateral Transfer ◽

Mating Types ◽

Zygote Nucleus ◽

Social Amoebae

AbstractSex promotes the recombination and reassortment of genetic material and is prevalent across eukaryotes. In social amoebae sex involves a promiscuous mixing of cytoplasm before zygotes consume the majority of cells. We report here the first genomewide characterisation of meiotic progeny in Dictyostelium discoideum. We find that recombination occurs at high frequency in pairwise crosses between all three mating types, despite the absence of the SPO11 enzyme that is normally required to initiate crossover formation. In crosses involving three strains, transient fusions involving more than two gametes frequently lead to triparental inheritance, with recombined nuclear haplotypes inherited from two parents and the mitochondrial genome from a third. Cells that do not contribute genetically to the Dictyostelium zygote nucleus thereby have a stake in the next haploid generation. We suggest that this lateral transfer helps to enforce cooperation in this confictual system.

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Faculty Opinions recommendation of Social amoebae trap and kill bacteria by casting DNA nets.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.726183138.793518810 ◽

2016 ◽

Author(s):

Richard Gomer

Keyword(s):

Social Amoebae

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Differential Gene Expression between Fungal Mating Types Is Associated with Sequence Degeneration

Genome Biology and Evolution ◽

10.1093/gbe/evaa028 ◽

2020 ◽

Vol 12 (4) ◽

pp. 243-258 ◽

Cited By ~ 3

Author(s):

Wen-Juan Ma ◽

Fantin Carpentier ◽

Tatiana Giraud ◽

Michael E Hood

Keyword(s):

Differential Expression ◽

Differentially Expressed Genes ◽

Mating Type ◽

Sex Chromosomes ◽

Sex Chromosome ◽

Gc Content ◽

Differentially Expressed ◽

Mating Types ◽

Sexual Antagonism ◽

Recombination Suppression

Abstract Degenerative mutations in non-recombining regions, such as in sex chromosomes, may lead to differential expression between alleles if mutations occur stochastically in one or the other allele. Reduced allelic expression due to degeneration has indeed been suggested to occur in various sex-chromosome systems. However, whether an association occurs between specific signatures of degeneration and differential expression between alleles has not been extensively tested, and sexual antagonism can also cause differential expression on sex chromosomes. The anther-smut fungus Microbotryum lychnidis-dioicae is ideal for testing associations between specific degenerative signatures and differential expression because 1) there are multiple evolutionary strata on the mating-type chromosomes, reflecting successive recombination suppression linked to mating-type loci; 2) separate haploid cultures of opposite mating types help identify differential expression between alleles; and 3) there is no sexual antagonism as a confounding factor accounting for differential expression. We found that differentially expressed genes were enriched in the four oldest evolutionary strata compared with other genomic compartments, and that, within compartments, several signatures of sequence degeneration were greater for differentially expressed than non-differentially expressed genes. Two particular degenerative signatures were significantly associated with lower expression levels within differentially expressed allele pairs: upstream insertion of transposable elements and mutations truncating the protein length. Other degenerative mutations associated with differential expression included nonsynonymous substitutions and altered intron or GC content. The association between differential expression and allele degeneration is relevant for a broad range of taxa where mating compatibility or sex is determined by genes located in large regions where recombination is suppressed.

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Giving the Amoebae Equal TimeThe Social Amoebae: The Biology of Cellular Slime Molds.John Tyler Bonner . Princeton University Press, 2008. 156 pp., illus. $19.95 (ISBN 9780691139395 cloth).

BioScience ◽

10.1525/bio.2010.60.2.11 ◽

2010 ◽

Vol 60 (2) ◽

pp. 156-157

Author(s):

Randy Wayne

Keyword(s):

Princeton University ◽

Cellular Slime ◽

Social Amoebae

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Deletion of the Schizophyllum commune Aα Locus: The Roles of Aα Y and Z Mating-Type Genes

Genetics ◽

10.1093/genetics/144.4.1437 ◽

1996 ◽

Vol 144 (4) ◽

pp. 1437-1444

Author(s):

C Ian Robertson ◽

Kirk A Bartholomew ◽

Charles P Novotny ◽

Robert C Ullrich

Keyword(s):

Mating Type ◽

Sexual Development ◽

Schizophyllum Commune ◽

Mating Types ◽

Developmental Pathway ◽

Mating Type Gene ◽

Mating Type Genes ◽

Regulatory Loci ◽

Type Gene

The Aα locus is one of four master regulatory loci that determine mating type and regulate sexual development in Schizophyllum commune. We have made a plasmid containing a URA1 gene disruption of the Aα Y1 gene. Y1 is the sole Aα gene in Aα1 strains. We used the plasmid construction to produce an Aα null (i.e., AαΔ) strain by replacing the genomic Y1 gene with URA1 in an Aα1 strain. To characterize the role of the Aα genes in the regulation of sexual development, we transformed various Aα Y and Z alleles into AαΔ strains and examined the acquired mating types and mating abilities of the transformants. These experiments demonstrate that the Aα Y gene is not essential for fungal viability and growth, that a solitary Z Aα mating-type gene does not itself activate development, that Aβ proteins are sufficient to activate the A developmental pathway in the absence of Aα proteins and confirm that Y and Z genes are the sole determinants of Aα mating type. The data from these experiments support and refine our model of the regulation of A-pathway events by Y and Z proteins.

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New Mating Types in Physarum polycephalum

Mycologia ◽

10.2307/3758667 ◽

1977 ◽

Vol 69 (2) ◽

pp. 421 ◽

Cited By ~ 9

Author(s):

O'Neil Ray Collins ◽

Hsi-Chang Tang

Keyword(s):

Physarum Polycephalum ◽

Mating Types

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A PCR-based Assay for Distinguishing between A1 and A2 Mating Types of Phytophthora capsici

Journal of the American Society for Horticultural Science ◽

10.21273/jashs04013-17 ◽

2017 ◽

Vol 142 (4) ◽

pp. 260-264

Author(s):

Ping Li ◽

Dong Liu ◽

Min Guo ◽

Yuemin Pan ◽

Fangxin Chen ◽

...

Keyword(s):

Genetic Diversity ◽

Mating Type ◽

Phytophthora Capsici ◽

Mating Types ◽

Sequence Repeat ◽

Chain Reaction ◽

Plant Parasite ◽

Dna Fragment ◽

Polymerase Chain ◽

Microsatellite Diversity

Sexual reproduction in the plant parasite Phytophthora capsici Leonian requires the interaction of two distinct mating types, A1 and A2. Co-occurrence of these mating types can enhance the genetic diversity of P. capsici and alter its virulence or resistance characteristics. Using an intersimple sequence repeat (ISSR) screen of microsatellite diversity, we identified, cloned, and sequenced a novel 1121-base pair (bp) fragment specific to the A1 mating type of P. capsici. Primers Pcap-1 and Pcap-2 were designed from this DNA fragment to specifically detect the A1 mating type. Polymerase chain reaction (PCR) using these primers amplified an expected 997-bp fragment from known A1 mating types, but yielded a 508-bp fragment from known A2 mating types. This PCR-based assay could be adapted to accurately and rapidly detect the co-occurrence of A1 and A2 P. capsici mating types from field material.

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