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 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.

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.

Pattern of differentiated nerve cells in hydra is determined by precursor migration

Development ◽  
1997 ◽  
Vol 124 (2) ◽  
pp. 569-576 ◽  
Author(s):  
G. Hager ◽  
C.N. David
Keyword(s):  
Cell Cycle ◽  
Cell Differentiation ◽  
Nerve Cell ◽  
Nerve Cells ◽  
The Body ◽  
Whole Body ◽  
Continuous Growth ◽  
Body Column ◽  
Nerve Cell Differentiation

The nervous system of the fresh water polyp hydra is built up as a nerve net spread over the whole body, with higher densities in the head and the foot. In adult hydra, as a result of continuous growth, new nerve cell differentiation takes place continuously. The pattern of nerve cell differentiation and the role of nerve cell precursor migration in establishing the pattern have been observed in vivo by vitally labelling precursor cells with DiI. The results indicate that nerve cell precursors arise directly from stem cells, complete a final cell cycle and divide, giving rise to two daughter cells, which differentiate into nerve cells. A subpopulation of the nerve cell precursors are migratory for a brief interval at the onset of the terminal cell cycle, then complete the cell cycle and divide at the site of differentiation. Labelling small patches of tissue in the head, body column and peduncle/foot with DiI indicated that formation of nerve cell precursors was nearly constant at all three positions. However, at least half of the labelled precursors in the body column migrated to the head or foot before differentiating; by contrast, precursors in head and foot differentiated in situ without significant migration. This redistribution leads to a net increase of nerve cell precursors in head and foot compared to body column and thus to the higher density of nerve cells in these regions.

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.

Commitment of stem cells to nerve cells and migration of nerve cell precursors in preparatory bud development in Hydra

Development ◽  
1980 ◽  
Vol 60 (1) ◽  
pp. 373-387
Author(s):  
Stefan Berking
Keyword(s):  
Stem Cells ◽  
Nerve Cell ◽  
Nerve Cells ◽  
The Body ◽  
Surrounding Tissue ◽  
Multipotent Stem Cells ◽  
Bud Development ◽  
Detectable Difference ◽  
And Migration ◽  
Tight Correlation

Budding in Hydra starts as an evagination of the double-layered tissue in the parent animal's gastric region. Five hours later the density of nerve cells in the bud's tissue doubles, representing the first detectable difference from the cellular composition of the surrounding tissue. These new nerve cells derive from multipotent stem cells which are in S-phase one day before evagination starts. Some of the bud's new nerve cells derive from stem cells which have migrated into the future bud's tissue after their commitment, apparently attracted by the bud anlage. The bud anlage recruits precursors of nerve cells even during starvation, during which nerve cell production ceases in other parts of the body. Furthermore, the bud anlage controls the duration of the development from commitment to final differentiation of the resulting nerve cells. Experiments with an inhibitor purified from hydra tissue indicate a tight correlation between stages of preparatory bud development and stages of recruitment of nerve cells for the bud. Whether or not precursors of nerve cells are involved in the control of bud formation in normal hydra, as compared to epithelial hydra which still bud though consisting of epithelial cells only, will be discussed.

Inhibition of stenotele differentiation by head tissue in Hydra

1987 ◽  
Vol 87 (2) ◽  
pp. 315-322
Author(s):  
TOSHITAKA FUJISAWA
Keyword(s):  
Epithelial Cells ◽  
Interstitial Cell ◽  
Position Effect ◽  
Cell Lineage ◽  
The Body ◽  
Regional Pattern ◽  
Inhibitory Signal ◽  
Body Column ◽  
Head Regeneration

Stenotele nematocytes in Hydra are differentiated predominantly in the proximal regions and in gradually decreasing numbers in the more distal regions of the body column. To test whether this position effect is directed by an inhibitory signal from head tissue or by a stimulatory signal from foot tissue, head or foot tissue was laterally grafted from one animal to different positions on another animal. Heads grafted to proximal positions strongly inhibited stenotele differentiation, while the foot exhibited no stimulatory effect. In addition, tissue from gastric regions showed intermediate levels of inhibition. Thus, the inhibitory signal appears to be distributed in a gradient along the body column from head to foot. During head regeneration, the inhibitory signal disappeared abruptly from the distal tip and reappeared rapidly. These results suggest that the inhibitory signal is involved in generating the regional pattern of stenotele differentiation. Head tissue from epithelial hydra, which lacks the interstitial cell lineage, also inhibited stenotele differentiation, suggesting that the inhibitory signal is localized in epithelial cells.

scholarly journals Distribution and dynamics of nematocyte populations in Hydra attenuata

1976 ◽  
Vol 21 (1) ◽  
pp. 15-34 ◽  
Author(s):  
H.R. Bode ◽  
K.M. Flick
Keyword(s):  
Transit Time ◽  
Reasonable Agreement ◽  
Data Distribution ◽  
Turnover Time ◽  
The Body ◽  
Battery Cell ◽  
Hydra Attenuata ◽  
Time Required ◽  
Body Column ◽  
Battery Cells

The distribution and dynamics of the 4 nematocyte populations of Hydra attenuata were investigated. Ninety-seven per cent of all nematocytes, including all 4 types, are mounted in the battery cells of the tentacles. The remaining 3%, including 2 types (stenoteles and holotrichous isorhizas) are mounted in the ectoderm of the body column. Eight-two per cent of all nematocytes are desmonemes; 11%, atrichous isorhizas; 5%, stenoteles; and 2%, holotrichous isorhizas. The density of each nematocyte population increases along the length of the tentacle towards the tip. The percentages of the total nematocytes per quarter of tentacle for each of the 4 quarters starting at the base is 15, 18, 25 and 42% respectively. The turnover time of the nematocyte populations in the tentacles was measured with 2 methods. First, the transit time for a carbon-marked battery cell from the base to the tip of the tentacle was measured. Secondly, the time required to replace the unlabelled nematocytes in the tentacles with [3H]proline-labelled nematocytes was measured. In both cases the time was 7–9 days. Based on these data (distribution and turnover time) a model was constructed for the dynamics of the nematocyte populations in the tentacles. The numbers of nematocytes produced dialy in the body column as predicted by the model are in reasonable agreement with the measured values.

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.

Bud induction in decapitated Hydra attenuata by 5-azacytidine: a morphological study

Development ◽  
1986 ◽  
Vol 93 (1) ◽  
pp. 105-119
Author(s):  
L. De Petrocellis ◽  
V. Maharajan ◽  
B. De Petrocellis ◽  
R. Minei
Keyword(s):  
Untreated Control ◽  
Morphological Study ◽  
The Body ◽  
Gene Products ◽  
Specific Expression ◽  
Bud Formation ◽  
Bud Induction ◽  
Hydra Attenuata ◽  
Body Column ◽  
Head Regeneration

The effect of 5-azacytidine (5-azaCR) on head regeneration and budding in hydra are reported. Hydra attenuata were exposed to various doses of 5-azaCR for 48 h and then decapitated and cultured. Head regeneration and bud formation were observed for 12 days after decapitation. Untreated control hydra regenerated heads within 7 to 8 days of decapitation with a budding index of 0·2. Buds invariably arose in the normal budding zone (below the gastric region). In the group treated with 0·8mM-5-azaCR, 9 days after decapitation head regeneration was seen in only 13% of animals, and an average of two buds per hydra were formed, most of which were in the vicinity of the distal end. Induction of budding was also seen in the animals that regenerated heads. In animals exposed to 1 mM-5-azaCR three main types of responses were observed 9 days after decapitation. (1) 44% of the animals regenerated normal heads; about half of them developed at least one bud and these buds originated in the budding zone. (2) 17·5% of the animals developed abnormal, long hypostome-like structures with single or bifurcated tentacles at theirtips. There were at least two buds per animal and they were invariably at abnormal sites. (3) 32% of the animals failed to regenerate heads, although they developed two buds. 87% ofthese buds originated in abnormal sites of the body column and a large number (72%) did not detach even by the 12th day after decapitation. Both 5 and 10 mM of 5-azaCR were toxic to the animals; the survivors formed large globeshaped heads. Bud induction was seen in 60% and 28% of animals in the 5 and 10 mM groups, respectively. These observations demonstrate that 5-azaCR induces bud formation in hydra at doses that inhibit head regeneration. This bud induction might be due to a specific expression of gene products responsible for bud formation.

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