Study of the nuclear cycle of four species of strictly anaerobic rumen fungi by fluorescence microscopy

Gaillard, Brigitte; Bretón, André; Bernalier, Annick

doi:10.1007/bf01570576

Cited by 11 publications

(5 citation statements)

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“…Among unicellular eukaryotes, in addition to ichthyosporeans, multinucleate cells are found in highly divergent lineages, such as amoebozoans, in several algal lineages within Archaeplastida, and in several lineages of Rhizaria and Excavata [ 5 ]. Among opisthokonts (i.e., the clade that contains animals, fungi, and their unicellular relatives), multinucleate cells, in addition to animals and ichthyosporeans, are found in most early branching fungal lineages, such as aphelids [ 16 ], rozellids [ 17 ], chytrid fungi [ 18 ], and filamentous ascomycetes. While it is probable that the multinucleate life stage evolved independently multiple times in distantly related lineages, a widespread presence of coenocytes in opisthokontal lineages suggests that a common ancestor of opisthokonts might have had a life cycle that included a coenocytic life stage.…”

Section: Discussionmentioning

confidence: 99%

Decoupling of Nuclear Division Cycles and Cell Size during the Coenocytic Growth of the Ichthyosporean Sphaeroforma arctica

2018

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SummaryCoordination of the cell division cycle with the growth of the cell is critical to achieve cell size homeostasis [1]. Mechanisms coupling the cell division cycle with cell growth have been described across diverse eukaryotic taxa [2, 3, 4], but little is known about how these processes are coordinated in organisms that undergo more complex life cycles, such as coenocytic growth. Coenocytes (multinucleate cells formed by sequential nuclear divisions without cytokinesis) are commonly found across the eukaryotic kingdom, including in animal and plant tissues and several lineages of unicellular eukaryotes [5]. Among the organisms that form coenocytes are ichthyosporeans, a lineage of unicellular holozoans that are of significant interest due to their phylogenetic placement as one of the closest relatives of animals [6]. Here, we characterize the coenocytic cell division cycle in the ichthyosporean Sphaeroforma arctica. We observe that, in laboratory conditions, S. arctica cells undergo a uniform and easily synchronizable coenocytic cell cycle, reaching up to 128 nuclei per cell before cellularization and release of daughter cells. Cycles of nuclear division occur synchronously within the coenocyte and in regular time intervals (11–12 hr). We find that the growth of cell volume is dependent on concentration of nutrients in the media; in contrast, the rate of nuclear division cycles is constant over a range of nutrient concentrations. Together, the results suggest that nuclear division cycles in the coenocytic growth of S. arctica are driven by a timer, which ensures periodic and synchronous nuclear cycles independent of the cell size and growth.

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Section: Discussionmentioning

confidence: 99%

Decoupling of Nuclear Division Cycles and Cell Size during the Coenocytic Growth of the Ichthyosporean Sphaeroforma arctica

2018

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“…Orpinomyces [18] and Anaeromyces [19] include polycentric species with multiflagellate and uniflagellate zoospores, respectively. Neocallimastix can be distinguished from the genera Piromyces and Caecomyces by multiflagellate zoospores and Caecomyces can be distinguished from Piromyces by its bulbous rhizoids [10]. Neocallimastix can be distinguished from the genera Piromyces and Caecomyces by multiflagellate zoospores and Caecomyces can be distinguished from Piromyces by its bulbous rhizoids [10].…”

Section: Discussionmentioning

confidence: 99%

“…Each thallus was composed of one sporangium with a branched rhizoid system. lf) were globular 6.5-8.5 ~m in diameter, without gamma particle-like bodies detectable by fluorescence with bisbenzimide [10], with a flagellum 20-25 ~m long. la, b).…”

Section: Morphological Characterizationmentioning

confidence: 99%

Piromyces rhizinflata nov. sp., a strictly anaerobic fungus from faeces of the Saharian ass: a morphological, metabolic and ultrastructural study

Breton

1991

FEMS Microbiology Letters

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A new species of strictly anaerobic chytridiomycete was isolated from dried faeces of the Saharian ass that had been stored for up to 150 days. Because of its monocentric thallus and uniflagellate zoospores it belongs to the genus Piromyces. It exhibits a high affinity for P. mae and P. dumbonica but differs from them in its morphological and ultrastructural characteristics. Its flagellar apparatus is similar to that of all previously reported fungi.

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“…Nuclei fluorescence was examined using transmitted-light microscope fitted with an exciter filter (G 355) and barrier filter (465) as described by Gaillard et al (1989).…”

Section: Organisms and Culture Conditionsmentioning

confidence: 99%

Special Properties of Polycentric Anaerobic Fungus Anaeromyces mucronatus

Fliegerová¹,

Pažoutová²,

Mrázek³

et al. 2002

Acta Vet. Brno

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The aim of this study was differentiation of polycentric rumen fungus of genera Anaeromyces using modern methods of molecular biology. Six polycentric anaerobic fungi isolated from cow, lama and bison were identified as Anaeromyces strains and analyzed for variability in internal transcribed spacers and fibrolytic activities. RFLP of both ITS1 and ITS1-4 fragments digested by restriction enzyme DraI separated studied strains into two groups with different cleavage profiles. Representatives of each group exhibited different hydrolytic enzyme activities. The largest differences were recorded in production of xylanase, β-endoglucanase and β-glucosidase. The possibility of using RFLP analysis of ITS regions to distinguish fungal isolates has been proved, however the results do not illuminate what kind of distinction is reflected in genetic variability of ITS regions. Rumen, fungi, anaerobic, cellulose, fiber, endoglucanaseAnaeromyces mucronatus was originally described from a Holstein cow in France (Breton et al. 1990) as the third polycentric anaerobic rumen fungal species besides Orpinomyces and Ruminomyces genera. However, Ruminomyces elegans has been reassigned to Anaeromyces elegans in 1993 (H o et al. 1990, 1993).The morphological differences among polycentric genera Orpinomyces and Anaeromyces are minimal and may vary under different culture conditions. Moreover, these species tend to lose their ability to produce sporangia in artificial media and therefore pure culture cannot be identified with absolute certainty (Barr et al. 1995).The development of molecular biological techniques in the last decade has enabled the new approach to the characterization of fungi. Li and Heath (1992) studied relationship of gut fungi based on ITS1 sequences and found that Anaeromyces isolates were more distant from other rumen fungi. The whole DNA sequences showed above 80% similarity among Piromyces, Neocallimastix and Orpinomyces, whereas the similarities between Anaeromyces and these three genera were only 70%.Despite the fact that fibrolytic enzymes of anaerobic rumen fungi have been studied intensively, there are no available data describing Anaeromyces cellulolytic and xylanolytic activities.The aim of our experiment was to determine the feasibility of using RFLP analysis of ITS fragment to distinguish among species rumen fungi assigned to Anaeromyces genera. In this paper six Anaeromyces strains isolated from different animals were studied using RFLP analysis of ITS1 and ITS 1-4 spacer. We present here also for the fist time endoglucanase and xylanase activities of Anaeromyces isolates. Materials and Methods Organisms and culture conditionsPolycentric anaerobic fungi were isolated by the method of Joblin (1981) from faeces of domestic ruminants

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Study of the nuclear cycle of four species of strictly anaerobic rumen fungi by fluorescence microscopy

Cited by 11 publications

References 4 publications

Decoupling of Nuclear Division Cycles and Cell Size during the Coenocytic Growth of the Ichthyosporean Sphaeroforma arctica

Decoupling of Nuclear Division Cycles and Cell Size during the Coenocytic Growth of the Ichthyosporean Sphaeroforma arctica

Piromyces rhizinflata nov. sp., a strictly anaerobic fungus from faeces of the Saharian ass: a morphological, metabolic and ultrastructural study

Special Properties of Polycentric Anaerobic Fungus Anaeromyces mucronatus

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