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Electron Microscopic Observations on the Symbiosis of Paramecium bursaria and its Intracellular Algae (1968)

KARAKASHIAN, STEPHEN J. ; KARAKASHIAN, MARLENE W. ; RUDZINSKA, MARIA A.

Oxford, UK : Blackwell Publishing Ltd

The @journal of eukaryotic microbiology 15 (1968), S. 0

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ISSN: 1550-7408

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Biology

Notes: SYNOPSIS. Observations were made on the fine structure of Paramecium bursaria and its intracellular Chlorella symbionts. Emphasis was placed on the structure of the algae and structural aspects of the relationship between the organisms.The algae are surrounded by a prominent cell wall and contain a cup-shaped chloroplast which lies just beneath the plasma membrane. Within the cavity formed by the chloroplast are a large nucleus, a mitochondrion, one or more dictyosomes, and numerous ribosomes. The chloroplast itself is made up of a series of lamellar stacks each containing 2–6 or more thylakoids with a granular stroma and starch grains intercalated between the stacks. The thylakoid stacks of mature algae are frequently more compact than those of recently divided algae. A large pyrenoid is located within the base of the chloroplast. It is made up of a granular or fibrillar matrix surrounded by a shell of starch. The matrix is bisected by a stack of 2 thylakoids. Prior to the division of the chloroplast the pyrenoid regresses; pyrenoids subsequently form in the daughter chloroplasts thru condensation of the matrix material and the reappearance of a starch shell. This shell appears to be formed by the hollowing-out of starch grains already present in the chloroplast stroma. Accordingly, in this case, starch moves from the stroma to the pyrenoid.The algae are located thruout the peripheral cytoplasm of the Paramecium. Each alga is located in an individual vacuole except immediately following division of the algae when the daughter cells are temporarily located in the vacuole which harbored the parental cell. Shortly thereafter the vacuole membrane invaginates, thereby isolating the daughter algae into individual vacuoles. Degenerating symbiotic algae are seen; because these are frequently found in vacuoles with bacteria, they are presumed to be undergoing digestion. Due to the conditions of culture these algae could have been either of intracellular or extracellular origin.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.1550-7408.1968.tb02095.x

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The rhythm of mating in Paramecium aurelia, syngen 3From a dissertation submitted in partial fulfillment of the requirements for the degree Doctor of Philosophy in the Department of Zoology, University of California, Los Angeles. A portion of this work was aided by a grant from the Committee on Research of the University of California and a grant to R. W. Siegel from the National Science Foundation. (1968)

Karakashian, Marlene W.

New York, NY [u.a.] : Wiley-Blackwell

Journal of Cellular Physiology 71 (1968), S. 197-209

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ISSN: 0021-9541

Keywords: Life and Medical Sciences ; Cell & Developmental Biology

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Biology , Medicine

Notes: The periodic mating behavior of some stocks of Paramecium aurelia, syngen 3, exhibits features typical of circadian rhythms. In the most extensively studied stock (37p), rhythmicity persists at least four days in continuous darkness, but disappears rapidly in continuous illumination (200 foot-candles). The period of the free-running rhythm is 22.2 hours, and relatively insensitive to ambient temperature. Cycles of illumination and temperature can regulate the mating rhythm. Changes in illumination at specified times in the circadian cycle will induce shifts in the phase of the rhythm. Stock differences with respect to the persistence of the rhythm and the environmental control of its phase have been observed.

Additional Material: 6 Ill.