Amphibian Morphogenesis Research Articles

Ernest Everett Just, Johannes Holtfreter, and the origin of certain concepts in embryo morphogenesis.

Ernest E. Just (1883-1941) is best known for his discovery of the "wave of negativity" that sweeps of the sea urchin egg during fertilization, and his elucidation of what are known as the fast and slow blocks to polyspermy. Just's contemporary Johannes Holtfreter (1901-1992) is known for his pioneering work in amphibian morphogenesis, which helped to lay the foundation for modern vertebrate developmental biology. This paper, after briefly describing the life and scientific contributions of Just, argues that his work and ideas strongly influenced two of the concepts for which Holtfreter is best known: tissue affinity and autoneuralization (or autoinduction). Specifically, this paper argues that, first, Just's experiments demonstrating developmental stage-specific changes in the adhesiveness of the blastomeres of cleavage embryos helped lay the foundation for Holtfreter's concept of tissue affinity and, second, Just's notion of the intrinsic irritability of the egg cell, which is evident in experimental parthenogenesis, strongly informed Holtfreter's concept of the nonspecific induction of neural tissue formation in amphibian gastrula ectoderm explants, a phenomenon known as autoinduction. Acknowledgment of these contributions by Just in no way diminishes the importance of Holtfreter's groundbreaking work. It does, however, extend the impact of Just's work into the area of embryo morphogenesis. It connects Just to Holtfreter and positions his work as an antecedent to embryo research that continues to this day.

Does Increased Water Access Empower Women?

The effect of Concanavalin A (Con A) on morphogenesis in Pleurodeles waltlii has been studied. Embryos were incubated with various concentrations of the lectin for a period of 6 days. Three stages of development were examined, late blastula, young gastrula and late gastrula. In the presence of the lectin at a concentration of 200, 150 or 100 micrograms/ml morphogenic movements were delayed, altered and finally blocked. At lower concentrations, 50 or 25 microgram/ml, there was a slight delay in gastrulation, but in some cases development was normal. These findings indicate that Con A exerted an inhibitory effect on amphibian morphogenesis and there is evidence that the lectin effect was concentration dependent. The effects of Con A were specific since they were totally inhibited by alpha-methyl-D-mannopyranoside (0.05 M). The viability of the 24 h lectin-treated embryos was demonstrated by washing experiments. Labelled Con A binding to the embryos was investigated before and after discarding the vitelline membrane. The results suggest a direct interaction between Con A and the cell surface and this was confirmed by using fluorescein isothiocyanate Con A.

Cloning and characterization of cDNAs encoding the integrin α2 and α3 subunits from Xenopus laevis

Integrins containing the α2 and α3 subunits associate with the β1 subunit to form distinct receptors with partially overlapping adhesive specificities. We report the cloning and sequence of cDNAs that encode the Xenopus orthologues of integrins α2 and α3 and the expression of these subunits during embryogenesis. Integrin α2 and α3 mRNAs are first expressed in the dorsal mesoderm and developing notochord at gastrulation. We also show that α3 mRNAs are expressed in the entire marginal zone of gastrulae dorsalized with LiCl but that this localization is lost in embryos ventralized by ultraviolet light. Immunoblots reveal that the α3 protein is expressed throughout early development, however, the α2 protein is not detected until late tailbud stages. Injection of full-length α3 transcripts into the animal poles of fertilized eggs results in embryonic defects in paraxial mesoderm attributed to the failure of somites to form segments. Injection of the α3 transcripts into the vegetal pole and overexpression of a 5′-truncated α3 control construct have no apparent affect on development or somite formation. These data suggest that normal position-specific expression of integrins is important in maintaining the proper organization of tissues during early amphibian morphogenesis.

Holtfreter revisited: Unsolved problems in amphibian morphogenesis

A number of fundamental problems in developmental and cell biology were articulated in Johannes Holtfreter's classic papers on tissue affinity and mechanisms of amphibian gastrulation. These problems remain unsolved and would be profitably revisited with modern methods of cell and molecular biology. © 1996 Wiley-Liss, Inc.

Holtfreter revisited: unsolved problems in amphibian morphogenesis.

A number of fundamental problems in developmental and cell biology were articulated in Johannes Holtfreter's classic papers on tissue affinity and mechanisms of amphibian gastrulation. These problems remain unsolved and would be profitably revisited with modern methods of cell and molecular biology.

Comparative analysis of the tissue distribution of three fibroblast growth factor receptor mRNAs during amphibian morphogenesis

We have used in situ hybridization to survey the expression pattern of three fibroblast growth factor receptor (FGFR) mRNAs (PFR-1, PFR-3 and PFR-4, which we previously identified as the amphibian Pleurodeles waltl homologs of human FGFR-1, FGFR-3 and FGFR-4, respectively) during morphogenesis. Previous work suggests that these FGFR mRNAs exhibit a distinct pattern of expression at early developmental stages. In the present study we have tested the functional activity of these receptors and shown that both FGF-1 (acidic FGF) and FGF-2 (basic FGF), but not FGF-7 (keratinocyte growth factor), can lead to their activation, suggesting that the three cDNAs encode functional receptors. Results from in situ hybridization indicate that various FGFRs are involved in various developmental events. Their involvement in these processes is both overlapping and distinct. During the differentiation of the central nervous system (CNS), PFR-1 and PFR-4 mRNAs show high levels of redundant expression, while the sites of expression of PFR-3 mRNA correlate with regions, such as the diencephalon and the rhombencephalon, undergoing important anatomic changes. The three FGFR mRNAs are distinctly expressed in the cranial ganglia, the pigmented epithelia of retina and the otic vesicles. Most significantly, we found that they are strongly expressed at cranial and branchial mesenchymal condensation sites. PFR-3 mRNA is expressed earlier in this process than PFR-1 and PFR-4 mRNAs. Furthermore PFR-3 mRNA is detected in the mesenchyme of the limb bud, while PFR-1 and PFR-4 mRNAs are found in the primordia of the skeletal elements. In addition, PFR-1 mRNA is expressed in axial mesenchyme and PFR-4 mRNA is detected in the melanophores, xanthophores and in the pronephros. These results suggest that various FGFRs may be involved in distinct developmental events including cell proliferation and differentiation. We also discuss the functional redundancy of the FGFR system during amphibian morphogenesis.

Weak applied voltages interfere with amphibian morphogenesis and pattern

AbstractWe have imposed steady DC electric fields over developing gastrula and neurula stage axolotls,Ambystoma mexicanum. These applied voltages were meant to confound cues provided by endogenous currents and fields that we have measured and believe to be controls of pattern and morphogenesis during early development. Applied voltages in the physiological range (25–75 mV/mm) cause severe disruption of development when imposed over neurulae whose orientation within the field is random or fixed. In the latter case, developmental defects are more likely to occur at that end of the neurula (rostral or caudal) that faces the cathode, or negative pole, of the applied field. In neurulae whose orientation within the field was fixed, the lowest magnitude producing developmental abnormality was between 5 and 25 mV/mm. Physiological measurement of the embryonic transepithelial potential (TEP) when perturbed by artificially applied voltages demonstrates that ectoderm facing the cathode is hyperpolarized, while ectoderm facing the anode is depolarized at all fields strengths tested. These data show that the electrical polarity of embryonic ectoderm is predictably disrupted by applied voltages. Though applied voltages exert this same effect on the ectoderm of gastrulae, exposure only during gastrulation does not lead to developmental abnormality. This observation demonstrates that the applied electric field does not harm the embryo in some non‐specific way and further emphasizes the stages of neurulation as those most sensitive to artificially applied or endogenous voltages. These data strongly support the notion the polarized natural voltages within amphibian embryos are controls of their emerging pattern. © 1994 Wiley‐Liss, Inc.

Lithium induces changes in the plasma membrane protein pattern of early amphibian embryos

The plasma membrane protein pattern of Rana ridibunda embryos subjected to lithium (Li) treatment at various stages of development was examined by two-dimensional gel electrophoresis. Differences were observed at the neurula stage not only as compared to controls but among lithium-treated embryos as well. Of particular interest was the presence of proteins, specific for the gastrula stage, in lithium-treated embryos. The results are discussed in relation to the well-known effect of lithium on amphibian morphogenesis.

Immunohistochemical localization of thyrotropic cells during amphibian morphogenesis: A stereological study

TSH-like producing cells have been studied using the peroxidase-antiperoxidase (PAP) immunohistochemical technique and rabbit anti-human thyrotropin (TSH) antiserum in the pars distalis of five species of amphibian anuran tadpoles at different stages of development as well as in 1-year-old postmetamorphic animals. This cell type has been identified and located in the pars distalis ventral zone of Bufo calamita showing no changes in its distribution pattern throughout development, and in Rana perezi where TSH-like cells were located in the central zone of the gland in premetamorphic stages, occupying the ventral zone at the end of metamorphosis. No immunoreaction has been observed in the other species studied ( Hyla meridionalis, Alytes cisternasii, and Pelobates cultripes). Morphometry and stereology were used to evaluate the changes observed in pars distalis volume and TSH immunoreactive cells during development. Pars distalis volume increased during the larval growth period and decreased throughout the metamorphic climax. TSH volume density and cellular area showed different evolutions in the species studied. The correlation between these parameters suggests a greatly proliferative period followed by an increase in cellular size. The changes observed in TSH total volume as well as the physiological data found by other authors lead us to conclude that there are two phases in amphibian development: first a period of TSH storage (pre- and prometamorphosis) and second a period of TSH release at metamorphic climax.

Immunocytochemical and morphometric study of prolactin cells during amphibian morphogenesis

The peroxidase-antiperoxidase (PAP) immunocytochemical technique and rabbit antihuman prolactin (PRL) antiserum were used to localize and identify PRL-producing cells in the pars distalis of Bufo calamita, Hyla meridionalis, Alytes cisternasii, Pelobates cultripes, and Rana perezi tadpoles at different stages of development as well as in 1-year-old postmetamorphic animals. This cell type was located throughout the gland in P. cultripes and R. perezi and in the caudal two-thirds in B. calamita, H. meridionalis, and A. cisternasii in premetamorphic animals. These distribution patterns do not show changes throughout development. Morphometry was used to evaluate the changes observed in pars distalis volume and stereological parameters of PRL immunoreactive cells during development. Pars distalis volume increased during the larval growth period and decreased throughout the metamorphic climax. PRL volume density and cellular area showed different patterns in the different species, although the correlation between these parameters suggests a period of great proliferative rate followed by changes in cellular size. The changes observed in PRL total volume suggest the existence of two phases in amphibian development: (i) a period of PRL storage during pre- and prometamorphosis and (ii) a period of release at the metamorphic climax.

Amphibian Development: A multipurpose treatment. Amphibian Morphogenesis. By HAROLD FOX. The Humana Press, Clifton, N.J. 1984. Pp. 277. $54

BioEssaysVolume 2, Issue 1 p. 42-43 Book Review Amphibian Development: A multipurpose treatment. Amphibian Morphogenesis. By HAROLD FOX. The Humana Press, Clifton, N.J. 1984. Pp. 277. $54 G. M. Malacinski, G. M. Malacinski Department of Biology, Indiana University, Bloomington, Indiana 47405, USA.Search for more papers by this author G. M. Malacinski, G. M. Malacinski Department of Biology, Indiana University, Bloomington, Indiana 47405, USA.Search for more papers by this author First published: January 1985 https://doi.org/10.1002/bies.950020115AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume2, Issue1January 1985Pages 42-43 RelatedInformation

Concanavalin A binding to amphibian embryo and effect on morphogenesis

ABSTRACT The effect of Concanavalin A (Con A) on morphogenesis in Pleurodeles waltlii has been studied. Embryos were incubated with various concentrations of the lectin for a period of 6 days. Three stages of development were examined, late blastula, young gastrula and late gastrula. In the presence of the lectin at a concentration of 200, 150 or 100 μg/ml morphogenic movements were delayed, altered and finally blocked. At lower concentrations, 50 or 25 μg/ml, there was a slight delay in gastrulation, but in some cases development was normal. These findings indicate that Con A exerted an inhibitory effect on amphibian morphogenesis and there is evidence that the lectin effect was concentration dependent. The effects of Con A were specific since they were totally inhibited by α-methyl-D-man-nopyranoside (0 05 M). The viability of the 24 h lectin-treated embryos was demonstrated by washing experiments. Labelled Con A binding to the embryos was investigated before and after discarding the vitelline membrane. The results suggest a direct interaction between Con A and the cell surface and this was confirmed by using fluorescein isothiocyanate Con A.

Inhibitors in amphibian morphogenesis: Enzymic degradation of an inhibitor for the vegetalizing factor

ABSTRACT A naturally occurring inhibitor for the vegetalizing inducing factor has been incubated with different enzymes. Pancreatic ribonuclease, ribonuclease-T1, deoxyribunuclease, neur-aminidase as well trypsin and papain diminish the inhibitor only very slightly or not at all. Pronase, a proteolytic enzyme from Streptomyces griseus inactivates the inhibitor completely.

Role of Water-Regulating Mechanisms in Amphibian Morphogenesis: A Quantitative Hypothesis

Role of Water-Regulating Mechanisms in Amphibian Morphogenesis: A Quantitative Hypothesis

Comparative Effects of Moni-, Di-, and Triphosphorylated Nucleosides on Amphibian Morphogenesis

ABSTRACT Treatment of Rana pipiens embryos with adenosinetriphosphate (ATP), adenosinemonophosphate (AMP-3), adenosinediphosphate (ADP), and other diphosphorylated nucleosides, either under ‘optimum conditions’ or with an overdose, resulted in formation of neural tubes about 4 hours (at 18° C.) ahead of untreated controls. With overdoses specific side-reactions appeared that differed with the substance applied. The rate of neurulation was directly related to the number of phosphate groups of the nucleotides used; it was fastest with ATP, intermediate with ADP, and slowest with AMP-3. The other side-reactions varied specifically and consistently with the number of phosphate groups, but the intensity of these reactions was not directly proportional to the number of phosphate groups present. Overdose treatment with ATP blocked development of head and gill structures immediately following precocious neurulation. This effect was largely reversible by addition of equimolar AMP-3 to solutions. Overdose treatment with AMP-3 apparently enhanced formation of head and gill structures. Development was first blocked at the tail-bud stage. ADP, IDP, and other diphosphorylated nucleosides at similar concentrations had no adverse effects following precocious neurulation and apparently stimulated growth of the entire embryo. All of the mononucleotides specifically accelerated neural-tube formation whether applied at the 2-cell stage, during the blastula stage, or at the stage of the open neural plate.

Temperature and Rate of Development of the Eggs of British Anura

A general account of past work on temperature in relation to amphibian morphogenesis is provided by Moore (I939), who gives also a fuller bibliography. The present paper is an attempt to apply the conclusions of his work, which is based on American Amphibia, especially five species of Rana, to certain British species. All individuals were obtained in the south of England: the common frog, Rana temporaria L., from the Lea Valley, the common toad, Bufo bufo (L.), from Richmond Park, and the edible frog, Rana esculenta L. forma typica, from West Kent. The habits of the three species differ considerably; Rana temporaria is moderately aquatic, but will wander some distance from water; Bufo bufo is aquatic only in the breeding season and is seldom to be taken in water during the summer; Rana esculenta, however, is the most aquatic of all the European Ranidae, being rarely found more than a few feet from the edge of a pond. The species are not very clearly related, Rana being firmisternous and Bufo arciferous: Rana temporaria and R. esculenta are probably the most distantly related European species of their genus. All three species are very widely distributed indeed, and are very common. R. esculenta is local in Britain, and is usually considered to have been introduced (cf. Smith, I939).