Regeneration by dissociated adult hydra cells: A histologic study

Chun, Yong Hyuck; Em, Johnson; Gabel, Bradley E. G.; Cadogan, Albert S. A.

doi:10.1002/tera.1420270112

Cited by 20 publications

(3 citation statements)

References 12 publications

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“…We can draw close morphological similarities between the initial developmental stages in Botrylloides WBR (cell aggregates, development of blastula-like structures, and invaginations of epithelial layers) and fundamental embryonic developmental stages (morula, blastula, and gastrula). A similar resemblance transpires when comparing Hydra WBR from dissociated cells [46] to embryonic development, implying a basic evolutionary root underlying whole body restoration events [47,48]. …”

Section: Discussionmentioning

confidence: 92%

Systemic Bud Induction and Retinoic Acid Signaling Underlie Whole Body Regeneration in the Urochordate Botrylloides leachi

et al. 2007

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Regeneration in adult chordates is confined to a few model cases and terminates in restoration of restricted tissues and organs. Here, we study the unique phenomenon of whole body regeneration (WBR) in the colonial urochordate Botrylloides leachi in which an entire adult zooid is restored from a miniscule blood vessel fragment. In contrast to all other documented cases, regeneration is induced systemically in blood vessels. Multiple buds appear simultaneously in newly established regeneration niches within vasculature fragments, stemming from composites of pluripotent blood cells and terminating in one functional zooid. We found that retinoic acid (RA) regulates diverse developmental aspects in WBR. The homologue of the RA receptor and a retinaldehyde dehydrogenase-related gene were expressed specifically in blood cells within regeneration niches and throughout bud development. The addition of RA inhibitors as well as RNA interference knockdown experiments resulted in WBR arrest and bud malformations. The administration of all-trans RA to blood vessel fragments resulted in doubly accelerated regeneration and multibud formation, leading to restored colonies with multiple zooids. The Botrylloides system differs from known regeneration model systems by several fundamental criteria, including epimorphosis without the formation of blastema and the induction of a “multifocal regeneration niche” system. This is also to our knowledge the first documented case of WBR from circulating blood cells that restores not only the soma, but also the germ line. This unique Botrylloides WBR process could serve as a new in vivo model system for regeneration, suggesting that RA signaling may have had ancestral roles in body restoration events.

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Section: Discussionmentioning

confidence: 92%

Systemic Bud Induction and Retinoic Acid Signaling Underlie Whole Body Regeneration in the Urochordate Botrylloides leachi

et al. 2007

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“…1C). These artificial preparations consist of two broad classes of cells (6). The greater number by far are fully differentiated adult cells which quickly achieve spatial orientation and migrate to a position consistent with their phenotype.…”

Section: Methodsmentioning

confidence: 99%

Developmental Toxicity and Structure/Activity Correlates of Glycols and Glycol Ethers

Em¹,

Gabel²,

Larson³

1984

Environmental Health Perspectives

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In recent years, the National lTxicology Program (NTP) has selected numerous glycol ethers for testing in routine laboratory mammals to ascertain the magnitude of their ability to injure the conceptus. From the lists available of ongoing and projected NTP test chemicals, a series of glycol ethers was selected for examination in vitro in the hydra assay. Also tested were additional chemicals of similar molecular configuration and/or composition. This short-term screening test placed the 14 glycols and glycol ethers tested into a rank order sequence according to their degree of hazard potential to developmental biology, i.e., their ability to interfere with the developmental events characteristic of all ontogenic systems. They were ranked according to the difference between the lowest dose or concentration overtly toxic to adults (A) and the lowest concentration interfering with development (D) of the artificial embryo of reaggregated adult hydra cells and the AID ratio.Published data from mammalian studies were available for a few of the test chemicals, and in each instance the hydra assay was in direct agreement with the outcomes reported of the more elaborate and standard animal tests. Ethylene glycol and ethylene glycol monomethyl ether were shown by both standard evaluations in mammals, and by the hydra assay, to disrupt embryos only at or very near to their respective adult toxic doses, whereas the mono-ethyl ether perturbed development at approximately one-fifth of the lowest dose overtly toxic to adults.Data from the hydra prescreen predict that, when tested by the NTP or other sponsor in the standard protocols employing mammals, the majority of the additional glycols and glycol ethers tested in hydra will be found capable of disrupting embryonic development only at, or very near to, exposure levels also overtly toxic to adults treated by the same route of administration. That is, they actually are not high priority items for additional testing provided human exposures are not anticipated at or near their respective adult toxic dose levels.No obvious structure activity relationship between these molecules and their developmental toxicity was found in the group assayed in hydra.

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“…During the course of development, the artificial embryos undergo the same phenomena as do mammalian embryos: proliferation and regression of cells, induction and response, creation of organ fields, induction of competence, spatial orientation, pattern fornation, membrane changes, directional migrations, metabolic changes, cellular morphogenesis, histogenesis, organogenesis, and functional ontogeny (7). Some developmental events, such as membrane changes and directional cellular migrations, are achieved by previously differentiated cells of the adult hydra, while other responses, such as organ field formation, occur through the action of previously undifferentiated or interstitial cells (12).…”

Section: Hydra Introductionmentioning

confidence: 99%

Teratological research using in vitro systems. V. Nonmammalian model systems.

Collins¹

1987

Environ Health Perspect

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In this review of alternative tests to whole-animal rodent studies, the use of sub-mammalian and subvertebrate systems is investigated. The history, methodology, known limitations, end points, dose response, and requirements of virus, hydra, planarian, cricket, fish, amphibian, Drosophila, and chicken embryo systems are discussed. PrefaceLiterature searches have been conducted on nonmammalian animal systems that have been proposed for use in screening potentially teratogenic compounds. Reference to work on viruses, hydra, planaria, crickets, Drosophila, fish, amphibians, and chick embryos were sought. The numbers of references found varied with each model system.Each model system has been reviewed independently. Information from published material has been summarized and relevant references have been cited. The lists of references should be considered extensive but not exhaustive. Most of the model systems proposed need further evaluation with known teratogens and nonteratogens.

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Regeneration by dissociated adult hydra cells: A histologic study

Cited by 20 publications

References 12 publications

Systemic Bud Induction and Retinoic Acid Signaling Underlie Whole Body Regeneration in the Urochordate Botrylloides leachi

Systemic Bud Induction and Retinoic Acid Signaling Underlie Whole Body Regeneration in the Urochordate Botrylloides leachi

Developmental Toxicity and Structure/Activity Correlates of Glycols and Glycol Ethers

Teratological research using in vitro systems. V. Nonmammalian model systems.

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