scholarly journals Regulation of interstitial cell differentiation in Hydra attenuata. IV. Nerve cell commitment in head regeneration is position-dependent

1978 ◽  
Vol 34 (1) ◽  
pp. 27-38
Author(s):  
M.S. Yaross ◽  
H.R. Bode
Keyword(s):  
Stem Cell ◽  
Cell Differentiation ◽  
Nerve Cell ◽  
Interstitial Cell ◽  
Fold Increase ◽  
Nerve Cells ◽  
Multipotent Stem Cell ◽  
Hydra Attenuata ◽  
Cell Commitment ◽  
Head Regeneration

In hydra, nerve cells are a differentiation product of the interstitial cell, a multipotent stem cell. Nerve cell commitment was examined during head regeneration in Hydra attenuata. Within 3 h of head removal there is a 10- to 20-fold increase in nerve cell commitment in the tissue which subsequently forms the new head. Nerve cell commitment is unaltered in the remainder of the gastric region. This local increase in nerve cell commitment is responsible for about one half the new nerve cells formed during head regeneration, while one half differentiate from interstitial cells that migrate into the regenerating tip.

Regulation of interstitial cell differentiation in Hydra attenuata. V. Inability of regenerating head to support nematocyte differentiation

1978 ◽  
Vol 34 (1) ◽  
pp. 39-52
Author(s):  
M.S. Yaross ◽  
H.R. Bode
Keyword(s):  
Stem Cell ◽  
Cell Differentiation ◽  
Interstitial Cell ◽  
Irreversible Change ◽  
Cellular Kinetics ◽  
Hydra Attenuata ◽  
Cell Commitment ◽  
Head Regeneration

Nematocyte differentiation was examined during head regeneration in Hydra attenuata. Nematocyte precursors were found to decrease in head-regenerating tissue. This decrease could not be attributed to decreased stem cell commitment or to altered cellular kinetics. The nematocyte precursors could be ‘rescued’ by regrafting a head onto the initially regenerating tissue only prior to the time at which head determination occurred. These results suggest that concurrent with head determination an irreversible change occurs in the tissue environment, resulting in decreased survival of cells committed to nematocyte differentiation.

Regulation of interstitial cell differentiation in Hydra attenuata. VI. Positional pattern of nerve cell commitment is independent of local nerve cell density

1981 ◽  
Vol 52 (1) ◽  
pp. 85-98
Author(s):  
S. Heimfeld ◽  
H.R. Bode
Keyword(s):  
Cell Density ◽  
Nerve Cell ◽  
Interstitial Cell ◽  
Cell Types ◽  
Nerve Cells ◽  
The Body ◽  
Hydra Attenuata ◽  
Cell Densities ◽  
Cell Commitment ◽  
Body Column

The interstitial cell of hydra is a multipotent stem cell, which produces nerve cells as one of its differentiated cell types. The amount of interstitial cell commitment to nerve differentiation varies in an axially dependent pattern along the body column. The distribution of nerve cell density has the same equivalent axial pattern. These facts have led to speculation that the regulation of nerve cell commitment is dictated by the nerve cell density. We examined this question by assaying interstitial cell commitment behaviour in 2 cases where the normal nerve cell density of the tissue had been perturbed: (1) in epithelial hydra in which no nerve cells were present; and (2) in hydra derived from regenerating-tip isolates in which the nerve density was increased nearly 4-fold. We found no evidence of regulation of nerve cell commitment in response to the abnormal nerve cell densities. However, the typical axial pattern of nerve commitment was still obtained in both sets of experiments, which suggests that interstitial cell commitment to nerve differentiation is dependent on some parameter of axial location that is not associated directly with the local nerve cell density.

scholarly journals Regulation of interstitial cell differentiation in Hydra attenuata. III. Effects of I-cell and nerve cell densities

1978 ◽  
Vol 34 (1) ◽  
pp. 1-26
Author(s):  
M.S. Yaross ◽  
H.R. Bode
Keyword(s):  
Nerve Cell ◽  
Cell Population ◽  
Interstitial Cell ◽  
Nerve Cells ◽  
The Body ◽  
Axial Position ◽  
Hydroxyurea Treatment ◽  
Cell Commitment ◽  
I Cells

The interstitial cell (i-cell) of hydra, a multipotent stem cell, produces two classes of differentiated cell types, nerve cells and nematocytes, throughout asexual growth. Using a new assay, the regulation of i-cell commitment to either nerve cell or nematocyte differentiation was investigated. This assay was used to determine the fractions of i-cells differentiating into nerve cells and nematocyte precursors in a variety of in vivo cellular milieus produced by hydroxyurea treatment, differential feeding, and reaggregation of dissociated cells. Nematocyte commitment was found to be positively correlated with the size of the i-cell population and independent of the axial position of the i-cells along the body column. This indicates that i-cell commitment to nematocyte differentiation may be regulated by feedback from the i-cell population. Nerve cell commitment was found to be correlated with regions of high nerve cell density. This suggests that nerve cell commitment is regulated by feedback from the nerve cell population or is dependent on axial position. Implications of such mechanisms for the regulation of i-cell population size and distribution are discussed.

scholarly journals Cell Cycle Kinetics and Development of Hydra Attenuata

1974 ◽  
Vol 16 (2) ◽  
pp. 359-375 ◽  
Author(s):  
C. N. DAVID ◽  
A. GIERER
Keyword(s):  
Cell Cycle ◽  
Stem Cells ◽  
Stem Cell ◽  
Interstitial Cell ◽  
Flow Model ◽  
Interstitial Cells ◽  
Nerve Cells ◽  
Stem Cell Divisions ◽  
Basal Disk ◽  
Hydra Attenuata

The differentiation of nerve cells and nematocytes in Hydra attenuata has been investigated by labelling interstitial cell precursors with [3H]thymidine and following by autoradiography the appearance of labelled, newly differentiated cells. Nematocyte differentiation occurs only in the gastric region where labelled nematoblasts appear 12 h and labelled nematocytes 72-96 h after addition of [3H]thymidine. Labelled nerves appear in hypostome, gastric region, and basal disk about 18 h after addition of [3H]thymidine. The lag in the appearance of labelled cells includes cell division of the precursor as well as differentiation since nerves and nematocytes have 2n postmitotic nuclear DNA content. A cell flow model is proposed for interstitial cells and their differentiated products. Stem cells occur as single interstitial cells or in pairs. Per cell generation about 60 % of the daughter cells of stem cell divisions remain stem cells and about 40 % differentiate nerves and nematocytes. Nerves differentiate directly from stem cells in about 1 day. Nematocyte differentiation requires 5-7 days including proliferation of a cluster of 4, 8, 16 or 32 interstitial cells and differentiation of a nematocyst capsule in each cell. The numbers of interstitial cells and nematoblasts predicted by the cell flow model from the rates of nerve differentiation (900 nerves/day/ hydra), nematocyte differentiation (1760 nematocyte nests/day/hydra) and stem cell proliferation (stem cell cycle = 24 h), agree with the numbers of these cells observed in hydra. The number of stem cells per hydra is 3000-6000 depending on assumptions about the time of determination. The ratio of nematocyte to nerve differentiation averaged over the whole hydra is 3:1. In the hypostome and basal disk interstitial cell differentiation occurs exclusively to nerve cells while in the gastric region the ratio of nematocyte to nerve differentiation is about 7:1.

Regulation of interstitial cell differentiation in Hydra attenuata. I. Homeostatic control of interstitial cell population size

1976 ◽  
Vol 20 (1) ◽  
pp. 29-46 ◽  
Author(s):  
H.R. Bode ◽  
K.M. Flick ◽  
G.S. Smith
Keyword(s):  
Cell Differentiation ◽  
Epithelial Cells ◽  
Population Size ◽  
Cell Population ◽  
Interstitial Cell ◽  
Normal Population ◽  
Cell Types ◽  
Hydra Attenuata ◽  
I Cells ◽  
Continuous Labelling

Mechanisms regulating the population size of the multipotent interstitial cell (i-cell) in Hydra attenuata were investigated. Treatment of animals with 3 cycles of a regime of 24 h in 10-2 M hydroxyurea (HU) alternated with 12 h in culture medium selectively killed 95–99% of the i-cells, but had little effect on the epithelial cells. The i-cell population recovered to the normal i-cell:epithelial cell ratio of I:I within 35 days. Continuous labelling experiments with [3H]thymidine indicate that the recovery of the i-cell population is not due to a change in the length of the cell cycle of either the epithelial cells or the interstitial cells. In control animals 60% of the i-cell population undergo division daily while 40% undergo differentiation. Quantification of the cell types of HU-treated animals indicates that a greater fraction of the i-cells were dividing and fewer differentiating into nematocytes during the first 2 weeks of the recovery after HU treatment. Therefore, the mechanism for recovery involves a shift of the 60:40 division:differentiation ratio of i-cells towards a higher fraction in division until the normal population size of the i-cells is regained. This homeostatic mechanism represents one of the influences affecting i-cell differentiation.

Developmental neurobiology of hydra, a model animal of cnidarians

2002 ◽  
Vol 80 (10) ◽  
pp. 1678-1689 ◽  
Author(s):  
Osamu Koizumi
Keyword(s):  
Cell Differentiation ◽  
Nerve Cell ◽  
Nerve Ring ◽  
Nerve Cells ◽  
Whole Body ◽  
Signal Molecules ◽  
Developmental Neurobiology ◽  
Nerve Net ◽  
Model Animal ◽  
Nerve Cell Differentiation

Hydra belongs to the class Hydrozoa in the phylum Cnidaria. Hydra is a model animal whose cellular and developmental data are the most abundant among cnidarians. Hence, I discuss the developmental neurobiology of hydra. The hydra nerve net is a mosaic of neural subsets expressing a specific neural phenotype. The developmental dynamics of the nerve cells are unique. Neurons are produced continuously by differentiation from interstitial multipotent stem cells. These neurons are continuously displaced outwards along with epithelial cells and are sloughed off at the extremities. However, the spatial distribution of each neural subset is maintained. Mechanisms related to these phenomena, i.e., the position-dependent changes in neural phenotypes, are proposed. Nerve-net formation in hydra can be examined in various experimental systems. The conditions of nerve-net formation vary among the systems, so we can clarify the control factors at the cellular level by comparing nerve-net formation in different systems. By large-scale screening of peptide signal molecules, peptide molecules related to nerve-cell differentiation have been identified. The LPW family, composed of four members sharing common N-terminal L(or I)PW, inhibits nerve-cell differentiation in hydra. In contrast, Hym355 (FPQSFLPRG-NH3) activates nerve differentiation in hydra. LPWs are epitheliopeptides, whereas Hym355 is a neuropeptide. In the hypostome of hydra, a unique neuronal structure, the nerve ring, is observed. This structure shows the nerve association of neurites. Exceptionally, the tissue containing the nerve ring shows no tissue displacement during the tissue flow that involves the whole body. The neurons in the nerve ring show little turnover, although nerve cells in all other regions turn over continuously. These associations and quiet dynamics lead me to think that the nerve ring has features similar to those of the central nervous system in higher animals.

Nerve cells of Drosophila Notch mutant are differentiated inside amphibian brain: a new approach for the analysis of genetic control of nerve cell differentiation

Genetica ◽  
1991 ◽  
Vol 85 (1) ◽  
pp. 23-34 ◽  
Author(s):  
L. Korochkin ◽  
S. Saveliev ◽  
A. Ivanov ◽  
M. Evgeniev ◽  
N. Bessova ◽  
...  
Keyword(s):  
Cell Differentiation ◽  
Genetic Control ◽  
Nerve Cell ◽  
Nerve Cells ◽  
New Approach ◽  
Nerve Cell Differentiation

Production of nerveless Hydra attenuata by hydroxyurea treatments

1979 ◽  
Vol 37 (1) ◽  
pp. 189-203
Author(s):  
P.G. Sacks ◽  
L.E. Davis
Keyword(s):  
Distribution Pattern ◽  
Nerve Cell ◽  
Regulatory Mechanism ◽  
Distribution Patterns ◽  
Nerve Cells ◽  
Behavioural Responses ◽  
Small Variance ◽  
New Type ◽  
Hydra Attenuata ◽  
Cell Densities

Hydroxyurea was used to produce hydra with varying nerve cell densities including a new type of nerveless animal. Hydra attenuata were treated with 10(−2) M hydroxyurea. By 23 days after treatment, 2 populations of animals are in culture. Both have a decrease in nerve cells. The first is a normal-coloured feeding animal (HU-R) and is recovering while the second is a pale non-feeding animal (HU-P). HU-P animals resemble nerveless animals in their lack of behavioural responses but they contain about 2% nerve cells. Upon hand feeding, some HU-P animals will recover but most will produce nerveless buds. Neverless hydra produced by hydroxyurea resemble nerveless animals produced by other techniques, in their behavioural, morphological and developmental properties. Normal animals, as cultured and in regeneration experiments, show a compact tentacle number distribution pattern with a small variance. Nerveless animals show broad tentacle distribution patterns with increased means and variances. It is suggested that a normal tentacle number regulatory mechanism is lacking or diminished in nerveless animals. This defect is correlated with hypostomal circumference and with nerve cells.

scholarly journals Elimination by Hydra interstitial and nerve cells by means of colchicine

1976 ◽  
Vol 21 (1) ◽  
pp. 1-13 ◽  
Author(s):  
R.D. Campbell
Keyword(s):  
Stem Cell ◽  
Epithelial Cells ◽  
Effective Treatment ◽  
Interstitial Cells ◽  
Nerve Cells ◽  
Digestive Cells ◽  
Hydra Attenuata ◽  
Derivatives Of

Hydra treated with colchicine or Colcemid become depleted of 95–99% of their interstitial cells and derivatives of this stem cell: nematoblasts, nematocytes and nerve cells. A second treatment removes most or all remaining interstitial cells. The most effective treatment is an 8-h immersion of whole Hydra attenuata in 0.04% Colcemid or 0.4% colchicine. Interstitial cells are eliminated through phagocytosis by both ectodermal and endodermal epithelial cells. The endodermal digestive cells send processes through the mesoglea which engulf interstitial cells and retract them into the endoderm. The resultant hydra, though devoid of nematocysts, can be artificially fed: these animals grow and bud and can be used to study the behaviour and development of tissue lacking nerve and interstitial cells.

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