Genetical and Cytological Evidence for Chromosomal Elimination in a True Slime Mold, Didymium Iridis

Collins, O’Neil Ray; Therrien, C. D.; Betterley, Donald A.

doi:10.1002/j.1537-2197.1978.tb06123.x

Cited by 15 publications

(2 citation statements)

References 32 publications

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“…A phenomenon that may be similar to stimulated selfing in P. polycephalum has been observed in mixtures of haploid and polyploid amoebae of D. iridis (Therrien & Collins, 1976;Collins, Therrien & Betterley, 1978). Collins et al interpreted their results in terms of a mechanism that does not seem applicable to the stimulated selfing we have observed in P. polycephalum: cellular and nuclear fusion followed by chromosomal elimination.…”

Section: Discussionmentioning

confidence: 69%

A new type of plasmodium formation inPhysarum polycephalum

Anderson

Truitt

1983

Genet. Res.

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SUMMARYHaploid amoebae ofPhysarum polycephalummay form plasmodia sexually by ‘crossing’, which involves cellular and nuclear fusion, or asexually by ‘selfing’, which occurs without nuclear fusion. In most amoebal strains, selfing is seen in clonal cultures only at very low frequency. In the present study, we have shown that selfing occurs at a similarly low frequency in mixtures of crossing-incompatible amoebae, but is stimulated in crossing-compatible mixtures. In certain compatible mixtures involving mutant strains, where crossing is temperature-sensitive, selfing may be stimulated even at a temperature that largely or wholly abolishes crossing. The extent to which selfing is stimulated appears to be influenced bymatB, a locus which is known to affect the frequency of amoebal fusion. We have failed to detect any filter-transmissible factor that might be responsible for the effects we have observed. We suggest a sequence of events that might bring about ‘stimulated selfing’ as a consequence of abortive crossing.

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Section: Discussionmentioning

confidence: 69%

A new type of plasmodium formation inPhysarum polycephalum

Anderson

Truitt

1983

Genet. Res.

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“…Furthermore, haploid cells in vitro are sometimes less sensitive to stresses (putative mutagens, fungicides) than expected (Metzger-Freed, 1974;Henriques et al, 1977;Upshall et al, 1977). And a growing literature on diploidization and gene silencing in polyploids (e.g., Ferris & Whitt, 1977a, 1977bGarcia-Olmeda et al, 1978) and differential chromosome elimination (Collins et al, 1978) suggests that buffering functions may not necessarily be central. Conversely, the arbitrary suppression of one X chromosome, possibly as a means of dosage compensation (Lyon, 1974;Monk & Kathuria, 1977;Lucchesi, 1978;Epstein et al, 1978), in female mammals suggests that partial haploidy may not be deleterious.…”

Section: Critique Of Existing Adaptational Hypothesesmentioning

confidence: 99%

On the Evolution of Complex Life Cycles in Plants: A Review and an Ecological Perspective

Willson¹

1981

Annals of the Missouri Botanical Garden

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Complex life cycles and alternation of generations are characteristic of many plants, a diploid sporophyte typically alternating with a haploid gametophyte. The prominence of each generation varies greatly among taxa. Purely phylogenetic or morphogenetic explanations of these differences are unsatisfying, as are those based solely on population fitness. Existing adaptational explanations seek selective advantages in diploidy and in sexual reproduction, but these explanations leave much to be explained -i.e., the existence of asexuality and of haploid organisms. Much of the existing variation in life cycles can be explained by selection on reproductive rates to meet the ecological problems of dispersal, colonization, niche preemption and exploitation, and mate competition. Placement of complex life cycles of plants in an ecological framework will, I hope, encourage specific studies exploring possible adaptive aspects and limitations on the evolution of life cycles in plants with different life histories.

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Development of Apogamic Amoebae From Heterothallic Lines of a Myxomycete, Didymium Iridis

Mulleavy

Collins

1979

American J of Botany

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By making appropriate crosses between heterothallic sexual clones of Didymium iridis we can recover apogamic lines in the F1 generation. In this organism, heterothallic forms typically produce a haploid myxamoebal stage, but recently two diploid myxamoebal clones homozygous for mating types were discovered. When these are crossed, A2A2 x A5A5, tetraploid Plasmodia are produced which later yield diploid F1 meiospores. Sixty‐four percent of the single‐spore‐derived clones produce both myxamoebae and Plasmodia, while the remainder do not progress past the myxamoebal stage. These results are consistent with the predictions that from tetraploid nuclei, mating types should segregate in the meiospores in a ratio of 1A2A2:4A2A5:1A5A5, and that myxamoebae heterozygous, A2A5, for mating type should yield Plasmodia apogamously. As the means for verifying relative ploidy levels of myxamoebae and Plasmodia, nuclear DNA was measured with a scanning microspectrophotometer.

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Genetical and Cytological Evidence for Chromosomal Elimination in a True Slime Mold, Didymium Iridis

Cited by 15 publications

References 32 publications

A new type of plasmodium formation inPhysarum polycephalum

A new type of plasmodium formation inPhysarum polycephalum

On the Evolution of Complex Life Cycles in Plants: A Review and an Ecological Perspective

Development of Apogamic Amoebae From Heterothallic Lines of a Myxomycete, Didymium Iridis

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