Biomedical subjects
F O Perkins
Publications and source records attributed to F O Perkins.
Ultrastructure of a marine Synechococcus possessing spinae.
Two Chesapeake Bay isolates of unicellular cyanobacteria belonging to the genus Synechococcus are described. Unicellular cyanobacteria are suspected to be important primary producers in estuarine and marine waters. One isolate (P-11-16) fluoresces red and forms green colonies. The other isolate (P-11-17) fluoresces orange and forms red colonies. Their ultrastructure is very similar to other isolates of Synechococcus except that spinae are formed and are attached to an outer wall layer not found in previously described species. The spinae are straight-walled cylinders, not flared at the base, are 44.0-65.0 nm in diameter, and range up to 2.7 micrometer in length. Substructure of the spinae wall consists of either material organized into stacks of rings or a strand of material helically coiled at a low (1-6 degrees) angle. Such material yielded a 6.0-9.2 nm cross-banding periodicity. Substructure of the rings or strand appeared to consist of bar-shaped, repeating units as seen in negatively stained material. Other procaryotic cell types with spinae, which were isolated from unincubated, natural seawater, are described.
Fine structure of the haplosporidan Kernstab, a persistent, intranuclear mitotic apparatus.
The fine structure of the haplosporidan mitotic apparatus is described from observations of plasmodial nuclei of Minchinia nelsoni, M. costalis, Minchinia sp., and Urosporidium crescens. The apparatus, which is the Kernstab of light-microscope studies, consists of a bundle of microtubules terminating in a spindle pole body (SPB) at each end of the bundle. A few microtubules extend from SPB to SPB, but most either extend from an SPB and terminate in the nucleoplasm or lie in the nucleoplasm, free of either SPB. The bundle lengthens during mitosis, increasing the SPB-to-SPB distance by a factor of 2 to 3 as compared to interphase nuclei. SPBs are not in contact with the nuclear envelope, being found always in the nucleoplasm which is delimited by the nuclear envelope throughout mitosis. The mitotic apparatus is persistent through interphase, at least in a form which is not significantly different from that found in mitotic nuclei.
Microtubules in the cortical region of the egg of Lymnaea during cortical segregation.
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The ultrastructure of holdfasts, "rhizoids", and "slime tracks" in Thraustochytriaceous fungi and Labyrinthula spp.
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Ultrastructure of the Nebenkörper or "secondary nucleus" of the parasitic amoeba Paramoeba perniciosa (Amoebida, Paramoebidae).
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The ultrastructure of fishing tentacle muscle in the jellyfish Chrysaora quinquecirrha: a comparison of contracted and relaxed states.
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Formation of centriole and centriole-like structures during meiosis and mitosis in Labyrinthula sp. (Rhizopodea, Labyrinthulida). An electron-microscope study.
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Chromosome number of a small protist: accurate determination.
Electron micrographs of serial sections through a meiotic prophase nucleus of the mycetozoan Labyrinthula sp. show that there are nine separate and distinct synaptinemal complexes. Since each complex represents a set of paired homologous chromosomes, it follows that the haploid chromosome number of this protist is nine.
Ultrastructure of vegetative stages in Labyrinthomyxa marina (Dermocystidium marinum), a commercially significant oyster pathogen.
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Fine structure of the oyster pathogen Minchinia nelsoni (Haplosporida, Haplosporidiidae).
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