Electron Microscopic Observation of the Sporangial Structure of an Actinomycete, Microellobosporia flavea

Rancourt, Martha W.; Lechevalier, H. A.

doi:10.1099/00221287-31-3-495

Cited by 15 publications

(6 citation statements)

References 5 publications

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“…A comparison of our sections of this strain of Actinoplanes with those lpublished for Alicroellobosporia favea (Rancourt and Lechevalier, 1963) and for a Streptosporangium strain (Rancourt, 1963) revealed that, whereas the strains of Actinoplanes and M1Iicroellobosporia had an intersporal substance, the strain of Streptosporangium did not. On the basis of the published information and some unpublished data on a strain of Streptosporangium, we believe, at the moment, that these three types of sporangia-bearing actinomycetes form their spores in about the same manner.…”

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“…He named these organisms Actinoplanes and added the family Actinoplanaceae to the Actinomycetales (Couch, 1955a, b). Other sporangia-bearing actinomycetes came to be recognized, and so far a total of five genera have been proposed by Couch (1963Couch ( , 1964 and one by Cross, Lechevalier, and Lechevalier (1963). The morphological differences between these various organisms can be summarized in the following key to the genera of the family Actinoplanaceae.…”

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confidence: 99%

“…Little is known about the ultramicroscopic structure of Actinoplanaceae. Rancourt and Lechevalier (1963) studied a species of Microellobosporia and Rancourt has investigated a species of Streptosporangium (1963). The aim of the present study was to investigate the ultramicroscopic structure of a strain of Actinoplanes during spore formation.…”

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Electron Microscopic Observation of the Sporangial Structure of a Strain of Actinoplanes

Lechevalier

Holbert²

1965

J Bacteriol

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Electron microscopic observation of the sporangial structure of a strain of Actinoplanes. J. Bacteriol. 89:217-222. 1965.-Actinoplanes sp. P 128 has polarly flagellated sporangiospores. The numerous flagella, formed by the helical winding of subfibrils, were seen clearly only in shadowed preparations. Flagella were never seen in sections of spores. Sporangial formation was followed by examining sections of sporangia at various stages of maturity. The sporangial envelope was the continuation of the outer sheath of the sporangiophore. The sporangiospores were formed by the division of hyphae enclosed within the sporangial wall. The spores were probably formed by simultaneous division of these hyphae. An intersporal substance, which seemed to originate from the outer sheaths of the intrasporangial hyphae, could be seen.

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Electron Microscopic Observation of the Sporangial Structure of a Strain of Actinoplanes

Lechevalier

Holbert²

1965

J Bacteriol

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“…Coincidentally, the sheath with a crevice was gone from those flagellated spores. There have been no reports on whether spores in sporangia have an extra sheath over the cell wall (3,11,12,18,19). We suspect that spores right after release from sporangia might still be wrapped with that newly found membranous sheath, and by unwrapping the sheath from the spore in a similar manner as ecdysis, flagella would be exposed and become free to move.…”

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Characterization of Actinoplanes missouriensis Spore Flagella

Uchida

Jang

Ohnishi

et al. 2011

Appl Environ Microbiol

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Actinoplanes missouriensis spores swim with a tuft of flagella. Flagella of newborn spores are wrapped with a membranous sheath. When the sheath is unwrapped, spores start swimming. Flagellar length is kept short, at around 1.9 m, which covers half the circumference of the spore.Actinoplanes species are Gram-positive, soil-inhabiting, filamentous bacteria that characteristically produce spores within a terminal sporangium (20,21). Spores are released from sporangia upon contact with water; the process is termed dehiscence (8). Actinoplanes spores grow into mycelia and eventually form sporangia under adverse conditions (7,8).Interestingly, a range of genera belonging to the order Actinomycetales, such as Actinoplanes, Catenuloplanes, Kineosporia, and Spirillospora, produce spores that possess flagella and are motile (4,8,13). Some Actinoplanes species possess a polar tuft of flagella or a bundle of flagella originating from a narrow area of the cell wall (8), while others have peritrichous flagella. Extensive studies on bacterial flagella have been performed using Salmonella enterica serovar Typhimurium (S. Typhimurium) (14). It will be very interesting to see how closely the spore flagella of Actinomycetales, which are phylogenetically distinct from S. Typhimurium, could be related with the paradigmatic flagella. In this study, we examined spore flagella of the Actinoplanes missouriensis 431 strain (NBRC 102363).Motility of flagellated spores. Water is not sufficient to trigger the release of spores from sporangia of A. missouriensis, but some unknown chemicals in the soil are required (4,7,13). To obtain motile spores, we used "activation medium," 10 mM phosphate buffer (pH 7.0) supplemented with soil extract, which is the water extract of the soil rich with decayed leaves. A. missouriensis mycelia were grown on 2% agar plates containing HAT medium (0.1% sucrose, 0.01% Casamino Acids, 0.05% KH 2 PO 4 , 0.2% humic acid, and 1% trace element solution, pH 7.5) at 30°C for 2 weeks. Cell motility was analyzed with a phase-contrast microscope, as previously described (15). Within 10 min after washing, spores were released from sporangia, and 20% of the population in a scope of the dark-field microscope started to swim. One hour later, the motile fraction was as high as 80% of the population observed and gradually decreased as time passed, and spore germination began. Three hours later, spores grew into mycelia, at which point spores lost motility. The average swimming speed of the motile spores was 135 Ϯ 25 m/s (mean Ϯ standard deviation) (Table 1). In comparison, those of S. Typhimurium and Bacillus subtilis cells measured under the same conditions were 29 Ϯ 5 m/s and 11 Ϯ 5 m/s, respectively. It is known that the Kineosporia sp. motile spores can swim at a speed of 160 m/s (17), which is as fast as Bdellovibrio cells (10). A. missouriensis spores belong to the fastest group among bacterial swimming species so far studied.Flagellar biogenesis observed by microscopy. A. missouriensis spores in the process of the life...

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“…In previous publications, we reported on the ultramicroscopic structure of strains of Microellobosporia (17) and Actinoplanes (13). In the case of the Actinoplanes sp., observation of ultrathin sections showed that a branched and coiled hypha grew inside a sporangial envelope and that its almost simultaneous division, perpendicular to its long axis, resulted in the formation of sporangiospores.…”

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Electron Microscopic Observation of the Sporangial Structure of Strains of Actinoplanaceae

Lechevalier

Holbert

1966

Journal of Bacteriology

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microscopic observation of the sporangial structure of strains of Actinoplanaceae. J. Bacteriol. 92:1228-1235. 1966.-Eight strains of Streptosporangium spp. and one strain each of Spirillospora albida and an Ampullariella-like Actinoplanes sp. were observed by electron microscopy. The sporangiospores of all these organisms had a smooth surface. All formed their sporangia by the ingrowth of a hypha inside a bag formed by the extension of the outer sheath of the sporangiophore. The sporogenic hypha was not branched in strains of Streptosporangium but was branched in S. albida and the Actinoplanes sp. Spore formation was by septation of the intrasporangial hyphae. When it occurred, septation took place by the same annular ingrowth of the cell wall common in gram-positive bacteria. The septum at the apex of the sporangiophore was formed before the others. Septation was seen to occur between two fully formed septa, indicating almost simultaneous formation of large segments dividing again, almost simultaneously, into smaller spore-sized segments.

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Electron Microscopic Observation of the Sporangial Structure of an Actinomycete, Microellobosporia flavea

Cited by 15 publications

References 5 publications

Electron Microscopic Observation of the Sporangial Structure of a Strain of Actinoplanes

Electron Microscopic Observation of the Sporangial Structure of a Strain of Actinoplanes

Characterization of Actinoplanes missouriensis Spore Flagella

Electron Microscopic Observation of the Sporangial Structure of Strains of Actinoplanaceae

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