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Amoebae of the Myxomycete Physarum polycephalum in the interphase state typically contain only one proflagellar apparatus in which the anterior kinetosome (anterior centriole) is attached to the microtubule organizing center 1 (mtoc 1). We built strains possessing more than one mtoc 1 and a variable number of anterior centrioles to allow the appearance of new structures. In 8% of the amoebae of these strains, the 1:1 attachment between the anterior centriole and the mtoc 1 is not always respected. In nine cases studied using tridimensional reconstructions from ultrastructural thin sections, the pattern of attachment was more complex. A mtoc 1 could be linked to several anterior centrioles, and/or reciprocally an anterior centriole could be linked to several mtoc 1. In one case, an anterior centriole was not linked to a mtoc 1 and in three cases, a single centriole exhibited anterior and posterior characteristics. These observations suggest that (1) each pair of centrioles constitutes a morphological and physiological entity that is distinct from the mitotic center (mtoc 1); (2) the attachment of the anterior centriole to the mtoc 1 occurs at the end of each mitosis; (3) there is an inductory process during the morphogenesis of the link between the anterior centriole and the mtoc 1; (4) the anterior characteristics of a centriole can be present in the absence of the link with the mtoc 1; (5) the anterior and posterior characteristics of a centriole are not exclusive of each other, ruling out the existence of a lineage corresponding to the anterior centriole and a lineage corresponding to the posterior centriole; and (6) the differences between anterior and posterior centrioles result from a maturation process. 相似文献
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在黏菌个体发育研究的培养过程中,经常发生原质团不能转变为孢子果的情况,使个体发育停留在营养生长阶段,利用液体发酵和有饲培养相结合的方法获得的绒泡菌属黏菌原质团进行了孢子果的诱导。在饥饿条件下,通过对光照和温度的调节,获得了绒泡菌属黏菌在不同培养条件下形成孢子果和菌核的最佳条件。在固体培养基和液体培养基中获得全白绒泡菌孢子果的最佳培养条件分别为:24℃、6,000lx光照和20℃、6,000lx光照;获得扁绒泡菌孢子果的最佳培养条件分别为:26℃、6,000lx光照和20℃、6,000lx光照。淡黄绒泡菌Physarum melleum在固体培养基上既可以获得孢子果也可以获得菌核,最佳培养条件分别为:26℃、6,000lx光照和22℃、3,000lx光照;在液体培养基中只能形成菌核,条件为:22℃、6,000lx光照。 相似文献
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Chitinase,β-1,3-glucanase, cellulase, xylanase and protease activity were detected in a crude enzyme preparation obtained from a slime
mold (Badhamia utricularis) which was grown on autoclaved mycelia ofPholiota nameko in a petri dish. The optimal pH of the enzyme preparation for lytic activity against fruit bodies ofLentinus edodes was 4.0, and those ofβ-1,3-glucanase and cellulase were the same. On the other hand, chitinase and protease showed optimal activity at pH 5.0 and
8.0, respectively. The lytic activity was stable below 40°C but completely inactivated at 70°C, and was most stable at pH
5.0. The studies of the optimal pH, thermal stability, and pH stability, and isoelectric focusing analysis of the enzyme preparation
suggest that chitinase,β-1,3-glucanase and cellulase activities may be responsible for lysis of fruit bodies of some mushrooms. The crude enzyme preparation
from the slime mold lysed fruit bodies of several mushrooms more efficiently than did commercial lytic enzymes preparations
(Driselase and Usukizyme). 相似文献
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Abstract The plasmodium of Physarum polycephalum exhibited positive chemotaxis towards l -alanine, l -aspartate, l -asparagine, l -glutamate, glycine, l -leucine, l -serine, and l -threonine and negative chemotaxis towards l -tryptophan. All attractant amino acids, except l -serine and l -threonine competed with each other; l -serine and l -threonine competed with the other amino acids but did not interfere with the response to each other. Cyclic nucleotides were attractants and cyclic 3',5'- or 2',3'-phosphate derivatives of either adenine or guanine were active, wheras compounds lacking the ring structure generally were not. Folic acid was an attractant whereas certain aromatic compounds were either inactive or repellent. 相似文献
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Haugen P Coucheron DH Rønning SB Haugli K Johansen S 《The Journal of eukaryotic microbiology》2003,50(4):283-292
Group I introns are relatively common within nuclear ribosomal DNA of eukaryotic microorganisms, especially in myxomycetes. Introns at position S516 in the small subunit ribosomal RNA gene are particularly common, but have a sporadic occurrence in myxomycetes. Fuligo septica, Badhamia gracilis, and Physarum flavicomum, all members of the family Physaraceae, contain related group IC1 introns at this site. The F. septica intron was studied at the molecular level and found to self-splice as naked RNA and to generate full-length intron RNA circles during incubation. Group I introns at position S516 appear to have a particularly widespread distribution among protists and fungi. Secondary structural analysis of more than 140 S516 group I introns available in the database revealed five different types of organization, including IC1 introns with and without His-Cys homing endonuclease genes, complex twin-ribozyme introns, IE introns, and degenerate group I-like introns. Both intron structural and phylogenetic analyses indicate a multiple origin of the S516 introns during evolution. The myxomycete introns are related to S516 introns in the more distantly related brown algae and Acanthamoeba species. Possible mechanisms of intron transfer both at the RNA- and DNA-levels are discussed in order to explain the observed widespread, but scattered, phylogenetic distribution. 相似文献
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In the heterothallic myxomycete Physarum polycephalum, uninucleate amoebae normally differentiate into syncytial plasmodia following heterotypic mating. In order to study the genetic control of this developmental process, mutations affecting the amoebal-plasmodial transition have been sought. Numerous mutants characterized by self-fertility have been isolated. The use of alkylating mutagens increases the mutant frequency over the spontaneous level but does not alter the mutant spectrum. Three spontaneous and 14 induced mutants have been analyzed genetically. In each, the mutation appears to be linked to the mating type locus. In three randomly selected mutants, the nuclear DNA content is the same in amoebae and plasmodia, indicating that amoebal syngamy does not precede plasmodium development in these strains. These results indicate that a highly specific type of mutational event, occurring close to or within the mating type locus, can abolish the requirement for syngamy normally associated with plasmodial differentiation. These mutations help define a genomic region regulating the switch from amoebal to plasmodial growth. 相似文献
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The conversion of the uninucleate amoebal form of Physarum polycephalum to the multi-nucleate plasmodial form is under the control of a genetic region which contains matA (or mt), a determinant of mating specificity. The region is the site of most gad mutations, which give amoebae the ability to produce plasmodia in clones without mating (ie, to self). In the present study, nonselfing revertants were isolated from two matA2-derived gad mutants and two matA3-derived gad mutants. Some revertants were found to have regained exactly, or nearly, the same phenotype as the original matA2 or matA3 strain. Others expressed new mating types, having gained the ability to mate with strains of the parental matA type. The results are compatible with a model in which new mating types arise from forward mutations (gad) and back mutations (npf or no plasmodium formation) occurring successively in a single gene, matA. 相似文献