Some Aspects of Normal Development in the Colonial Ciliate Zoöthamnium Alternans

Summers, F. M.

doi:10.2307/1537891

Cited by 15 publications

(22 citation statements)

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“…Zoothamnium alternans is a close nonsymbiotic relative of Z. niveum (Clamp and Williams, 2006;Faure-Fremiet, 1930) that is regularly found in the same habitat but distinguished from the latter by its smaller size (Vopel et al, 2001). Summers (1938) reported a division rate of 8 h in developing Z. alternans colonies. Interestingly, aposymbiotic Z. niveum colonies reared from swarmers, which had lost their bacteria in the laboratory, did not display rapid growth and appeared similar in size to Z. alternans (Vopel et al, 2001), In addition, ultrastructural studies (Bauer-Nebelsick et al, 1996b) indicate that Z. niveum gains at least part of its nutrition from its chemoautotrophic bacteria.…”

Section: Discussionmentioning

confidence: 99%

Cell proliferation and growth inZoothamnium niveum (Oligohymenophora, Peritrichida) — Thiotrophic bacteria symbiosis

2009

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Chemolithoautotrophic, sulphide-oxidizing (thiotrophic) symbioses represent spectacular adaptations to fluctuating environmental gradients and survival is often accomplished when growth is fuelled by sufficient nourishment through the symbionts leading to fast cell proliferation. Here we show 5'-bromo-2'deoxyuridine (BrdU) pulse labelling of vegetative growing Zoothamnium niveum, a colonial ciliate obligately associated with thiotrophic ectosymbionts, and demonstrate age related growth profiles in three heteromorphic host cell types. At the colony's apex, a large top terminal zooid performed high proliferation activity, which decreased significantly with increasing colony age but was still present in old colonies indicating that this cell possesses lifelongcell division potential. In contrast, terminal branch zooids proliferated independent of colony age but appeared to be limited by their cell division capacity predetermined by branch size, thus leading to the strict, feather-shaped colony form. Appearance of labelled terminal branch zooids allowed us to distinguish a highly proliferating apical colony region from an almost inactive, senescent basal region. In macrozooids attached to the colony, extensive BrdU labelling suggests that DNA synthesis occurs in preparation for a new generation. As motile swarmers, the macrozooids seem to be arrested in the cell cycle and mitosis and cell division occur when the swarmer settles and transforms into a top terminal zooid buildingup a new colony.

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Section: Discussionmentioning

confidence: 99%

Cell proliferation and growth inZoothamnium niveum (Oligohymenophora, Peritrichida) — Thiotrophic bacteria symbiosis

2009

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“…Life cycle of the peritrich ciliate Zoothamnium niveum . Multicellular development begins when a haploid disperser, or telotroch, settles and attaches to a substratum and then begins to secrete a stalk (Summers, 1938 b ). The first cell division is asymmetric, resulting in a larger product that becomes the apical zooid and a smaller product that becomes the terminal zooid of the first branch (Fauré‐Fremiet, ; Summers, 1938 b ).…”

Section: Alveolatamentioning

confidence: 99%

“…Multicellular development begins when a haploid disperser, or telotroch, settles and attaches to a substratum and then begins to secrete a stalk (Summers, 1938 b ). The first cell division is asymmetric, resulting in a larger product that becomes the apical zooid and a smaller product that becomes the terminal zooid of the first branch (Fauré‐Fremiet, ; Summers, 1938 b ). Each division of the apical cell produces an apical zooid and a new branch, while branches grow by continued divisions of their respective terminal zooids (Summers, 1938 b ).…”

Section: Alveolatamentioning

confidence: 99%

“…The first cell division is asymmetric, resulting in a larger product that becomes the apical zooid and a smaller product that becomes the terminal zooid of the first branch (Fauré‐Fremiet, ; Summers, 1938 b ). Each division of the apical cell produces an apical zooid and a new branch, while branches grow by continued divisions of their respective terminal zooids (Summers, 1938 b ). Subapical zooids cease dividing and become feeding microzooids, some of which differentiate into macrozooids and disperse as telotrochs (Summers, 1938 b ).…”

Section: Alveolatamentioning

confidence: 99%

“…Each division of the apical cell produces an apical zooid and a new branch, while branches grow by continued divisions of their respective terminal zooids (Summers, 1938 b ). Subapical zooids cease dividing and become feeding microzooids, some of which differentiate into macrozooids and disperse as telotrochs (Summers, 1938 b ). Actively dividing zooids sometimes differentiate into ‘microgamonts’, free‐swimming cells capable of conjugation, the sexual process in ciliates (Summers, 1938 a , b ).…”

Section: Alveolatamentioning

confidence: 99%

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Cellular differentiation and individuality in the ‘minor’ multicellular taxa

et al. 2013

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Biology needs a concept of individuality in order to distinguish organisms from parts of organisms and from groups of organisms, to count individuals and compare traits across taxa, and to distinguish growth from reproduction. Most of the proposed criteria for individuality were designed for ‘unitary’ or ‘paradigm’ organisms: contiguous, functionally and physiologically integrated, obligately sexually reproducing multicellular organisms with a germ line sequestered early in development. However, the vast majority of the diversity of life on Earth does not conform to all of these criteria. We consider the issue of individuality in the ‘minor’ multicellular taxa, which collectively span a large portion of the eukaryotic tree of life, reviewing their general features and focusing on a model species for each group. When the criteria designed for unitary organisms are applied to other groups, they often give conflicting answers or no answer at all to the question of whether or not a given unit is an individual. Complex life cycles, intimate bacterial symbioses, aggregative development, and strange genetic features complicate the picture. The great age of some of the groups considered shows that ‘intermediate’ forms, those with some but not all of the traits traditionally associated with individuality, cannot reasonably be considered ephemeral or assumed transitional. We discuss a handful of recent attempts to reconcile the many proposed criteria for individuality and to provide criteria that can be applied across all the domains of life. Finally, we argue that individuality should be defined without reference to any particular taxon and that understanding the emergence of new kinds of individuals requires recognizing individuality as a matter of degree.

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Morphology, taxonomy and molecular phylogeny of three marine peritrich ciliates, including two new species: Zoothamnium apoarbuscula n. sp. and Z. apohentscheli n. sp. (Protozoa, Ciliophora, Peritrichia)

et al. 2020

Mar Life Sci Technol

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Zoothamnium is a speciose genus, most species of which have incomplete morphological data based on modern criteria. In the present study, the morphology of three species of Zoothamnium, i.e., Z. apoarbuscula n. sp., Z. apohentscheli n. sp., and Z. alternans, collected in Qingdao, China, was revealed using living observation and silver staining. In addition, the SSU rDNA of each species was sequenced for phylogenetic analyses. Zoothamnium apoarbuscula n. sp. is characterized by its umbellate colony which is up to 900 μm high, dichotomously branched stalk, differentiation of zooids, and infundibular polykinety 3 comprising three equal-length ciliary rows. Zoothamnium apohentscheli n. sp is characterized by its large colony up to 1700 μm high, alternately branched stalk, and infundibular polykinety 3 comprising three equal-length ciliary rows. A population of Z. alternans is described in detail. Phylogenetic analyses based on SSU rDNA sequence data revealed that species with an alternately branched stalk cluster together in gene trees and probably represent an independent lineage within the genus Zoothamnium.

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Some Aspects of Normal Development in the Colonial Ciliate Zoöthamnium Alternans

Cited by 15 publications

References 2 publications

Cell proliferation and growth inZoothamnium niveum (Oligohymenophora, Peritrichida) — Thiotrophic bacteria symbiosis

Cell proliferation and growth inZoothamnium niveum (Oligohymenophora, Peritrichida) — Thiotrophic bacteria symbiosis

Cellular differentiation and individuality in the ‘minor’ multicellular taxa

Morphology, taxonomy and molecular phylogeny of three marine peritrich ciliates, including two new species: Zoothamnium apoarbuscula n. sp. and Z. apohentscheli n. sp. (Protozoa, Ciliophora, Peritrichia)

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