Cyst Stages of Opisthonecta henneguyi

Rosenberg, Lauren E.

doi:10.2307/3222743

Cited by 7 publications

(3 citation statements)

References 3 publications

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“…As soon as all the remaining granular groups disappear, a cyst membrane (ectocyst) is formed. Its derivation seems to agree with that of Gastrostyla steinii in which an ectocyst is formed from the pellicle (40), differently therefore from other ciliates in which it is secreted by the cytoplasmic surface( 10, 18,27). Further.…”

Section: Stage D (D Insupporting

confidence: 57%

Relationships between Feeding Organelles and Encystment in Oxytricha fallax Stein

Hashimoto¹

1962

The Journal of Protozoology

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SYNOPSIS. In Oxytricha fallax, extrusion of all the excretory crystals and some refractile bodies occurs when food is with held. The precystic animals thus resulting become transparent and undergo dedifferentiation of organelles. First the undulating membrane and cytostome are entirely resorbed, producing astomial forms. Then the adoral membranelles vanish gradually, accompanying which the somatic ciliature such as the cirri comes to be resorbed. Occasionally, early precystic animals retaining the intact feeding organelles reorganize spontaneously (physiological regeneration), but they become irreversibly encystable by high‐temperature treatment; for hastening resorption of feeding organelles accelerates encystment. When transparent animals at various precystic stages are cut in half the posterior fragment (PF) always encysts faster than the anterior one (AF) from the same parent, except that some of the AFs from early stages reorganize into normal vegetative forms. The time difference for completion of encystment between an AF and PF pair is at early stages larger than at later ones. If the anterior part of AF is further excised, the time difference for encystment between AF and PF from the same source becomes smaller or indistinguishable, with the exception that some AFs from early stages regenerate instead. Further, when the anterior part of whole precystic animals is removed, the time for their encystment is reduced. Also in this case, the fragments from early stages normally regenerate. From these results, it is presumed that the adoral membranelles tend to inhibit the encystment process as they do the initiation of an oral primordium in dividers and regenerants of Stentor and other ciliates. Accordingly, when resorption of membranelles becomes extensive as precystic processes progress, their dominance over and inhibition of cyst formation may be diminishing. From the fact that regeneration of fragments from early stages into normal forms may be due to retention of the undulating membrane, its resorption is considered to be an essential prerequisite for the initiation of irreversible encystment.

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Section: Stage D (D Insupporting

confidence: 57%

Relationships between Feeding Organelles and Encystment in Oxytricha fallax Stein

Hashimoto¹

1962

The Journal of Protozoology

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“…Little is known about the ultrastructure and composition of peritrich resting cysts (Bussers and Jeuniaux 1974; Dodd 1962; Finley and Lewis 1960; Rosenberg 1938; Walker, Edward, and Suchard 1989), and the presence of chitin is not clear. The present work is an ultrastructural study of the resting cyst and the encystment process in the peritrich ciliate Opisthonecta henneguyi .…”

mentioning

confidence: 99%

Ultrastructure, Eneystment and Cyst Wall Composition of the Resting Cyst of the Peritrich Ciliate Opisthonecta henneguyi

Calvo

Fernandez-Aliseda

Garrido

et al. 2003

J Eukaryotic Microbiology

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The cyst wall of Opisthonecta henneguyi has been studied ultrastructurally and cytochemically by light and electron microscopy, as well as by chemical and electrophoretic analyses, to examine the structure of the cyst wall and its composition. The cyst wall consists of four morphologically distinct layers. The ectocyst is a thin dense layer. The mesocyst is the thickest layer and is composed of a compact material. The endocyst is a thin layer like the ectocyst, but less dense. The granular layer varies in thickness and is composed of a granular material. In the resting cyst, kinetosomes of both oral apparatus and trochal band as well as the myoneme system are maintained, and only cilia are resorbed. The sugars present in the cyst wall are predominantly N-acetylglucosamine (90%) and glucose (10%). The mesocyst is composed of chitin, and the endocyst includes glycoproteins and acid mucopolysaccharides. During secretion of the cyst wall, the endocyst and granular layer are secreted from precursors synthesized "de novo". No cytoplasmic precursors of ectocyst and mesocyst have been detected.

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“…Yet it is known that some cortical structures of the trophic stage persist in cysts, such as the stripes of Stentor coeruleus and S. polymorphus ( 2 2 ) and the dorsal bristles of Euplotes taylori(9); but it is uncertain whether or not these remain unchanged. In other ciliates, extra-nuclear organelles are reported as being resorbed entirely in encystment (43, 9,[11][12][13][14][15]17,21,29,32) ; this brings up the question whether morphogenesis is strictly de novo in excystment. From my previous hypothesis(l1) that the original AZM and UM may inhibit encystment, their resorption in the precystic stage was considered essential to encystment.…”

mentioning

confidence: 99%

Localization of Ciliary Primordia in Induced Abnormal Cysts of Oxytricha. fallax

Hashimoto¹

1964

The Journal of Protozoology

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SYNOPSIS. Precystic organisms embedded in agar become abnormal cysts. Some of them are excystable rod-like or ellipsoid forms and the others, non-excystable flat ones. Major axis of the rod-like or ellipsoid cysts is parallel with the body axis of the previous precystic organisms, because when the cysts are formed the protoplast within the secreted cyst walls rotates or agitates slightly around the major axis but movement around the minor axis is precluded.The fibrillar structures appearing in excystment from abnormal cysts are biIaterally symmetrical, different from the normal spherical cysts showing radial symmetry. The two poles from which the fibrils radiate are situated opposite each other but not a t the extremities of the cyst. The locus of the anterior pole corresponds to the site of oral primordia in dividers and reorganizers.When the anterior part of the original adoral membranelles (AZM) in the early precystic animals is removed, the ellipsoid cysts from the abbreviated animals show a disturbance CCORDING to my previous study on the re-A formation of ciliature in excystment of Oxytricha fallax( 1 2 ) the oral primordia, including adoral membranelles ( AZM) , undulating membrane (UM) , and the cirri, seem to be formed in morphogenetic relation to the thickening of certain fibrillar structures appearing only in the resting cystic stage. All of these show separate primordia similar to those in dividers and regenerators of the present species( 10). Such multiplicity is found also in reorganization of the silverline system in the reproductive cysts of Colpoda duodenaria ( 2 7 ).The question arises: How are the ciliary primordia derived? To trace their origin from precystic or trophic stages may provide clues concerning genetic continuity of the ciliature between non-cystic and cystic animals. Unfortunately the information available is scanty. Yet it is known that some cortical structures of the trophic stage persist in cysts, such as the stripes of Stentor coeruleus and S. polymorphus ( 2 2 ) and the dorsal bristles of Euplotes taylori(9); but it is uncertain whether or not these remain unchanged. In other ciliates, extra-nuclear organelles are reported as being resorbed entirely in encystment (43, 9,[11][12][13][14][15]17,21,29,32) ; this brings up the question whether morphogenesis is strictly de novo in excystment. From my previous hypothesis(l1) that the original AZM and UM may inhibit encystment, their resorption in the precystic stage was considered essential to encystment. Is the inhibition-dominance theory further applicable to the initiation of ciliary primordia from their sites in later excystment or not? of the anterior fibrillar arrangement. The primoidium ot the future AZM runs straight from the anterior extremity of the cyst toward the uninjured posterior pole. Ellipsoid cysts from precystic animals after the posterior region is removed similarly have disturbed fibrils near the Fosterior extremity of the cyst. The AZM primordium then arising on excystment extends from the uninjured anterior p...

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Cyst Stages of Opisthonecta henneguyi

Cited by 7 publications

References 3 publications

Relationships between Feeding Organelles and Encystment in Oxytricha fallax Stein

Relationships between Feeding Organelles and Encystment in Oxytricha fallax Stein

Ultrastructure, Eneystment and Cyst Wall Composition of the Resting Cyst of the Peritrich Ciliate Opisthonecta henneguyi

Localization of Ciliary Primordia in Induced Abnormal Cysts of Oxytricha. fallax

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