Mitochondrial inheritance patterns in Didymium iridis are not influenced by stage of mating competency.
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To test whether the timing of transition to mating competency affected mitochondrial transmission patterns in D. iridis. Reciprocal crosses were made by combining mating compatible strains that differed in their competency to mate. The results were compared to crosses where both mating strains were competent at the time of combining and crosses where somatic fusion of plasmodia was allowed. The results show that the mating competency of the parental strains at the time of confronting a compatible mate does not affect mitochondrial transmission patterns, mating efficiency or the likelihood of biparental inheritance. However the timing of plasmodial formation is delayed when precompetent and competent strains are mated compared to when both strains are competent at the time of mixing. We also observed that somatic fusion of plasmodia did not appreciably increase the incidence of biparental inheritance compared to crosses where individual plasmodia were isolated. These results provide additional evidence of the variable nature of mitochondrial inheritance in D. iridis within crosses and between mating trials. (+info)
In vivo expression of a group I intron HEG from the antisense strand of Didymium ribosomal DNA.
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Two different isolates of the myxomycete Didymium iridis harbour homing endonuclease genes that are expressed from group I introns inserted into identical sites within the small subunit ribosomal DNA. The homing endonuclease proteins are related in sequence, and their gene structures share similar features such as the presence of small spliceosomal introns and functional polyadenylation sites. However, they are transcribed from opposite strands of the ribosomal DNA and presumable by different RNA polymerases. We have previously described the in vivo expression of the I-DirI homing endonuclease from within the ribosomal RNA precursor. In this paper, we demonstrate the in vivo expression of the I-DirII homing endonuclease from the opposite strand of the Didymium rRNA gene. A comparison of the expression strategies of the two genes demonstrates the feasibility of antisense expression and provides insight into nucleolar gene expression. (+info)
Description and culture of a new succulenticolous Didymium (Myxomycetes).
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A new succulenticolous Myxomycete species, Didymium wildpretii, found on decaying remains of various species of cacti, is described from two arid zones of the world. This species was collected from central Mexico, at the southern limit of the Chihuahuan Desert, and from the Canary Islands (Spain). The new species has small, pale yellow sporocarps, 0.1-0.7 mm high, that are sessile or have short, orange-yellow, calcareous stalks and small, uniformly warted spores. The stability of the taxonomic characters of the species was confirmed with both moist chamber cultures and spore-to-spore culture on agar. Life cycle events are described from germination to sporulation. Myxomycete specimens were examined with scanning electron microscopy and light microscopy, and micrographs of relevant morphological details are included. (+info)