Comparison of the effects of vitamin A on limb development and regeneration in Xenopus laevis tadpoles

Development ◽  
1986 ◽  
Vol 91 (1) ◽  
pp. 35-53
Author(s):  
S. R. Scadding ◽  
M. Maden
Keyword(s):  
Cell Cycle ◽  
Vitamin A ◽  
Xenopus Laevis ◽  
Limb Development ◽  
Complete Inhibition ◽  
Complete Suppression ◽  
Dual Action ◽  
Pattern Regulation

The purpose of these experiments was to compare the effects of vitamin A on developing and regenerating limbs in Xenopus laevis tadpoles. Each tadpole had one hindlimb amputated to induce regeneration while the contralateral developing limb was left intact. Tadpoles at stages 50 through 54 were treated by immersion in retinol palmitate at doses ranging from 0·3 to 75 i.u.ml−1, for periods ranging from 1 to 14 days. Developing limbs usually became hypomorphic as a result of the treatment, with results varying with stage and treatment from slight phalange derangements to total disruption of pattern, or complete inhibition of limb development. Regenerating limbs gave a variety of responses including hypomorphic regeneration, proximodistal or anteroposterior duplication of skeletal elements, or complete suppression of regeneration. The response to retinol palmitate of developing limbs was clearly different from regenerating limbs. Hypotheses which might explain the results were discussed and a hypothesis which, proposed a dual action of vitamin A affecting both the cell cycle and the mechanism of pattern regulation was proposed.

Effects of vitamin A and other retinoids on the differentiation and morphogenesis of the integument and limbs of vertebrates

1991 ◽  
Vol 69 (2) ◽  
pp. 263-273 ◽  
Author(s):  
Keith J. Johnson ◽  
Steven R. Scadding
Keyword(s):  
Cell Differentiation ◽  
Vitamin A ◽  
Thyroid Hormones ◽  
Mechanism Of Action ◽  
Limb Development ◽  
Common Mechanism ◽  
Complex Processes ◽  
Normal Differentiation ◽  
Pattern Regulation ◽  
Related Compounds

Exogenous vitamin A is a well-known teratogen and modifies the course of cell differentiation, embryonic development, and morphogenesis. Recent evidence has shown that vitamin A and related compounds (the "retinoids") are likely natural morphogens, carrying out important roles in such processes as limb development and epithelial differentiation. Retinoids can modify the differentiation of individual cells and can induce specific modifications of morphogenesis in such structures as epithelial appendages, developing limbs, and regenerating limbs. Evidence is accumulating that there may be a common mechanism of action underlying these diverse phenomena. Retinoids may enter cells and induce changes in gene transcription in a manner similar to that reported for steroid and thyroid hormones and their receptors. Retinoids are particularly useful probes in the study of cell differentiation and morphogenesis because an understanding of their action can provide clues to the mechanisms involved in the complex processes of normal differentiation, morphogenesis, and pattern regulation.

Vitamin A inhibits amphibian tail regeneration

1987 ◽  
Vol 65 (2) ◽  
pp. 457-459 ◽  
Author(s):  
Steven R. Scadding
Keyword(s):  
Retinoic Acid ◽  
Vitamin A ◽  
Xenopus Laevis ◽  
Ambystoma Mexicanum ◽  
Complete Inhibition ◽  
Notophthalmus Viridescens ◽  
Tail Regeneration ◽  
Dose Levels ◽  
Dose Dependent

The objective of this investigation was to determine what effect vitamin A had on tail regeneration in Notophthalmus viridescens adults, in Ambystoma mexicanum larvae, and in Xenopus laevis tadpoles. Notophthalmus viridescens and Ambystoma mexicanum had their tails amputated and then were treated with retinol palmitate by immersion in concentrations known to cause proximodistal duplications in regenerating limbs. Xenopus laevis tadpoles had their tails amputated and then were treated with either retinol palmitate by immersion, or with retinoic acid administered by implantation of silastin blocks containing retinoic acid. The results ranged from no effect at all at the lower dose levels used, to complete inhibition of tail regeneration at higher dose levels. The degree of inhibition of tail regeneration appeared to be dose dependent. In no case were any duplicated or accessory structures formed analogous to those observed in regenerating limbs. This result suggests that the morphogenetic processes involved in tail regeneration are at least in some ways different from those occurring in limbs, where a similar vitamin A treatment would cause proximodistal duplication or production of accessory limb structures.

The effects of local application of retinoic acid on limb development and regeneration in tadpoles of Xenopus laevis

Development ◽  
1986 ◽  
Vol 91 (1) ◽  
pp. 55-63
Author(s):  
S. R. Scadding ◽  
M. Maden
Keyword(s):  
Retinoic Acid ◽  
Vitamin A ◽  
Xenopus Laevis ◽  
Anion Exchange ◽  
Limb Development ◽  
Exchange Resin ◽  
Anion Exchange Resin ◽  
Mode Of Administration ◽  
Resin Beads ◽  
The Right

Vitamin A can have different effects on developing and regenerating limbs depending on the mode of administration. Previous work has demonstrated the differential effect of retinol palmitate on limb development and regeneration in Xenopus laevis. The purpose of the present investigation was to determine the effects of vitamin A on limb development and regeneration in Xenopus when administered by a local implantation method. Xenopus tadpoles had both hindlimbs implanted with either a block of silastin carrying retinoic acid or an anion exchange resin bead carrying retinoic acid and then the right hindlimb was amputated and the effect of the retinoic acid on limb development and regeneration was studied. The results showed that in developing hindlimbs the effects of silastin implants carrying retinoic acid was to cause skeletal reductions or deletions similar to those induced by immersion of the tadpole in retinol palmitate. On the other hand, in regenerating hindlimbs, the silastin implants caused a range of skeletal reductions and deletions as well as occasional accessory structures but notably induced no proximodistal (PD) duplications, unlike the effect of immersion in retinol palmitate where PD duplications were a common response. Implantation of anion exchange resin beads carrying retinoic acid had no significant effect on either development or regeneration beyond stage 50, presumably because the dose of the retinoic acid was so low. Thus the results suggest that the mode of administration of vitamin A has a very significant influence on its effects. The significance of this observation for vitamin A experiments on limbs is discussed.

scholarly journals An intrinsic cell cycle timer terminates limb bud outgrowth

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Joseph Pickering ◽  
Constance A Rich ◽  
Holly Stainton ◽  
Cristina Aceituno ◽  
Kavitha Chinnaiya ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Rna Sequencing ◽  
Late Stage ◽  
Limb Development ◽  
Limb Bud ◽  
Limb Outgrowth ◽  
Bmp Signalling ◽  
Mesenchyme Cells

The longstanding view of how proliferative outgrowth terminates following the patterning phase of limb development involves the breakdown of reciprocal extrinsic signalling between the distal mesenchyme and the overlying epithelium (e-m signalling). However, by grafting distal mesenchyme cells from late stage chick wing buds to the epithelial environment of younger wing buds, we show that this mechanism is not required. RNA sequencing reveals that distal mesenchyme cells complete proliferative outgrowth by an intrinsic cell cycle timer in the presence of e-m signalling. In this process, e-m signalling is required permissively to allow the intrinsic cell cycle timer to run its course. We provide evidence that a temporal switch from BMP antagonism to BMP signalling controls the intrinsic cell cycle timer during limb outgrowth. Our findings have general implications for other patterning systems in which extrinsic signals and intrinsic timers are integrated.

scholarly journals Protein kinase C acts downstream of calcium at entry into the first mitotic interphase of Xenopus laevis.

1990 ◽  
Vol 1 (3) ◽  
pp. 315-326 ◽  
Author(s):  
W M Bement ◽  
D G Capco
Keyword(s):  
Cell Cycle ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Xenopus Laevis ◽  
Mitotic Cell ◽  
Cortical Granule ◽  
Mitotic Cell Cycle ◽  
Cleavage Furrow ◽  
Kinase C ◽  
Cortical Granule Exocytosis

Transit into interphase of the first mitotic cell cycle in amphibian eggs is a process referred to as activation and is accompanied by an increase in intracellular free calcium [( Ca2+]i), which may be transduced into cytoplasmic events characteristic of interphase by protein kinase C (PKC). To investigate the respective roles of [Ca2+]i and PKC in Xenopus laevis egg activation, the calcium signal was blocked by microinjection of the calcium chelator BAPTA, or the activity of PKC was blocked by PKC inhibitors sphingosine or H7. Eggs were then challenged for activation by treatment with either calcium ionophore A23187 or the PKC activator PMA. BAPTA prevented cortical contraction, cortical granule exocytosis, and cleavage furrow formation in eggs challenged with A23187 but not with PMA. In contrast, sphingosine and H7 inhibited cortical granule exocytosis, cortical contraction, and cleavage furrow formation in eggs challenged with either A23187 or PMA. Measurement of egg [Ca2+]i with calcium-sensitive electrodes demonstrated that PMA treatment does not increase egg [Ca2+]i in BAPTA-injected eggs. Further, PMA does not increase [Ca2+]i in eggs that have not been injected with BAPTA. These results show that PKC acts downstream of the [Ca2+]i increase to induce cytoplasmic events of the first Xenopus mitotic cell cycle.

The NIMA-related kinase X-Nek2B is required for efficient assembly of the zygotic centrosome in Xenopus laevis

2000 ◽  
Vol 113 (11) ◽  
pp. 1973-1984 ◽  
Author(s):  
A.M. Fry ◽  
P. Descombes ◽  
C. Twomey ◽  
R. Bacchieri ◽  
E.A. Nigg
Keyword(s):  
Cell Cycle ◽  
Xenopus Laevis ◽  
Basal Body ◽  
Chromatin Condensation ◽  
Embryonic Cells ◽  
Serine Threonine Kinase ◽  
Cell Cycles ◽  
Functional Studies ◽  
Mammalian Cell Cycle ◽  
Egg Extracts

Nek2 is a mammalian cell cycle-regulated serine/threonine kinase that belongs to the family of proteins related to NIMA of Aspergillus nidulans. Functional studies in diverse species have implicated NIMA-related kinases in G(2)/M progression, chromatin condensation and centrosome regulation. To directly address the requirements for vertebrate Nek2 kinases in these cell cycle processes, we have turned to the biochemically-tractable system provided by Xenopus laevis egg extracts. Following isolation of a Xenopus homologue of Nek2, called X-Nek2B, we found that X-Nek2B abundance and activity remained constant through the first mitotic cycle implying a fundamental difference in Nek2 regulation between embryonic and somatic cell cycles. Removal of X-Nek2B from extracts did not disturb either entry into mitosis or the accompanying condensation of chromosomes providing no support for a requirement for Nek2 in these processes at least in embryonic cells. In contrast, X-Nek2B localized to centrosomes of adult Xenopus cells and was rapidly recruited to the basal body of Xenopus sperm following incubation in egg extracts. Recruitment led to phosphorylation of the X-Nek2B kinase. Most importantly, depletion of X-Nek2B from extracts significantly delayed both the assembly of microtubule asters and the recruitment of gamma-tubulin to the basal body. Hence, these studies demonstrate that X-Nek2B is required for efficient assembly of a functional zygotic centrosome and highlight the possibility of multiple roles for vertebrate Nek2 kinases in the centrosome cycle.

Morphogenesis of the amphibian limb blastema: The relationship between pattern and form

Development ◽  
1984 ◽  
Vol 79 (1) ◽  
pp. 165-181
Author(s):  
Nigel Holder ◽  
Susan Reynolds
Keyword(s):  
Pattern Formation ◽  
Vitamin A ◽  
Short Range ◽  
Range Cell ◽  
Limb Pattern ◽  
The Relationship ◽  
Pattern Regulation ◽  
Thigh Region ◽  
Short Arc ◽  
Number Of Cells

A relationship between pattern formation and field shape is established following the formation of rounded blastemas on lower arm limb stumps after treatment with vitamin A. Pattern formation is not affected by alteration in blastemal shape caused by removal of the dermis from the thigh region of the leg. We conclude, therefore, that blastemal shape does not play a causal role in establishing limb pattern. Data relating the number of cells present between the cardinal axial poles of blastemas and the size of blastemas is discussed in terms of short arc intercalation and short range cell—cell interactions during pattern regulation.

scholarly journals Cell cycle dynamics of an M-phase-specific cytoplasmic factor in Xenopus laevis oocytes and eggs.

1984 ◽  
Vol 98 (4) ◽  
pp. 1247-1255 ◽  
Author(s):  
J Gerhart ◽  
M Wu ◽  
M Kirschner
Keyword(s):  
Cell Cycle ◽  
Xenopus Laevis ◽  
Germinal Vesicle ◽  
Small Scale ◽  
Xenopus Laevis Oocytes ◽  
Germinal Vesicle Breakdown ◽  
Cytoplasmic Factor ◽  
M Phase ◽  
Cytostatic Factor ◽  
Meiotic Cycle

We have examined the regulation of maturation-promoting factor (MPF) activity in the mitotic and meiotic cell cycles of Xenopus laevis eggs and oocytes. To this end, we developed a method for the small scale extraction of eggs and oocytes and measured MPF activity in extracts by a dilution end point assay. We find that in oocytes, MPF activity appears before germinal vesicle breakdown and then disappears rapidly at the end of the first meiotic cycle. In the second meiotic cycle, MPF reappears before second metaphase, when maturation arrests. Thus, MPF cycling coincides with the abbreviated cycles of meiosis. When oocytes are induced to mature by low levels of injected MPF, cycloheximide does not prevent the appearance of MPF at high levels in the first cycle. This amplification indicates that an MPF precursor is present in the oocyte and activated by posttranslational means, triggered by the low level of injected MPF. Furthermore, MPF disappears approximately on time in such oocytes, indicating that the agent for MPF inactivation is also activated by posttranslational means. However, in the absence of protein synthesis, MPF never reappears in the second meiotic cycle. Upon fertilization or artificial activation of normal eggs, MPF disappears from the cytoplasm within 8 min. For a period thereafter, the inactivating agent remains able to destroy large amounts of MPF injected into the egg. It loses activity just as endogenous MPF appears at prophase of the first mitotic cycle. The repeated reciprocal cycling of MPF and the inactivating agent during cleavage stages is unaffected by colchicine and nocodazole and therefore does not require the effective completion of spindle formation, mitosis, or cytokinesis. However, MPF appearance is blocked by cycloheximide applied before mitosis; and MPF disappearance is blocked by cytostatic factor. In all these respects, MPF and the inactivating agent seem to be tightly linked to, and perhaps participate in, the cell cycle oscillator previously described for cleaving eggs of Xenopus laevis (Hara, K., P. Tydeman, and M. Kirschner, 1980, Proc. Natl. Acad. Sci. USA, 77:462-466).

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