Secondary lens formation from the cornea following implantation of larval tissues between the inner and outer corneas of Xenopus laevis tadpoles

Development ◽  
1981 ◽  
Vol 64 (1) ◽  
pp. 121-132
Author(s):  
Julie G. Reeve ◽  
Arthur E. Wild
Keyword(s):  
Experimental Design ◽  
Xenopus Laevis ◽  
Basal Layer ◽  
Limb Bud ◽  
Lens Regeneration ◽  
Body Tissues ◽  
Single Lens ◽  
Brain Implants ◽  
Lens Formation ◽  
Stimulatory Factor

Secondary lens formation from the cornea of larval Xenopus laevis has been used as a measure of the lens-inducing capacities of various larval Xenopus tissues. The experimental design employed involved implantation of selected body tissues between the inner and outer corneas of stage-5O tadpole eyes, in such a way that the integrity of the inner cornea and eye cup was not disrupted. Implantation of retina, pituitary, limb blastema or limb bud resulted in secondary lens formation from the outer cornea. Such lenses were similar in appearance to stage-5 lens regenerates described by Freeman (1963). No secondary lenses were observed in eyes receiving either heart or hind brain implants or in eyes which underwent corneal separation but which received no implant. It is concluded that the retina is the natural source of a stimulatory factor which initiates and maintains corneal transformation to lens during lens regeneration following lensectomy. Influences emanating from pituitary, limb blastema and limb bud, but apparently not from heart or hind brain, are able to act on cornea in a way similar to the retinal factor. Furthermore, our findings support the contention that in the normal eye, the inner cornea is a barrier to the passage of retinal factor and so maintains the single lens structure of the eye. When this barrier is by-passed by lens-inducing tissue, as in the present experimental design, lens formation from the cornea is able to take place. Electronmicroscopical studies have shown that the inner cornea, in the stage-50 tadpole eye, consists of a dense meshwork of collagen fibrils and a basal layer of cohesive elongated mesenchymal cells well suited for this barrier function.

scholarly journals FGF1 Promotes Xenopus laevis Lens Regeneration

2018 ◽  
Author(s):  
Lisa Moore ◽  
Kimberly J. Perry ◽  
Cindy Sun ◽  
Jonathan J. Henry
Keyword(s):  
Xenopus Laevis ◽  
Culture Method ◽  
Dominant Negative ◽  
Dependent Manner ◽  
Regeneration Rate ◽  
Culture Techniques ◽  
Lens Regeneration ◽  
Fgfr Signaling ◽  
Lens Formation

AbstractBackgroundThe frog Xenopus laevis has notable regenerative capabilities, including that of the lens. The neural retina provides the factors that trigger lens regeneration from the cornea, but the identity of these factors is largely unknown. In contrast to the cornea, fibroblast growth factors FGF1, 8, and 9 are highly expressed within the retina, and are potential candidates for those factors. The purpose of this study is to determine whether specific FGF proteins can induce lens formation, and if perturbation of FGFR signaling inhibits lens regeneration.MethodsA novel cornea epithelial culture method was developed to investigate the sufficiency of FGFs in lens regeneration. Additionally, transgenic larvae expressing dominant negative FGFR1 were used to investigate the necessity of FGFR signaling in lens regeneration.ResultsTreatment of cultured corneas with FGF1 induced lens regeneration in a dose-dependent manner, whereas treatment with FGF2, FGF8, or FGF9 did not result in significant lens regeneration. Inhibition of FGFR signaling decreased the lens regeneration rate for in vitro eye cultures.ConclusionThe culture techniques developed here, and elsewhere, have provided reliable methods for examining the necessity of various factors that may be involved in lens regeneration. Based on the results demonstrated in this study, we found that FGF1 signaling and FGFR activation are key factors for lens regeneration in Xenopus.

Conservation of Pitx1 expression during amphibian limb morphogenesis

2006 ◽  
Vol 84 (2) ◽  
pp. 257-262 ◽  
Author(s):  
W Y Chang ◽  
F KhosrowShahian ◽  
M Wolanski ◽  
R Marshall ◽  
W McCormick ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Xenopus Laevis ◽  
Expression Patterns ◽  
Limb Bud ◽  
Eleutherodactylus Coqui ◽  
Limb Buds ◽  
Homeodomain Transcription Factor ◽  
Limb Morphogenesis ◽  
Pelvic Limb

In contrast to the pattern of limb emergence in mammals, chicks, and the newt N. viridescens, embryos such as Xenopus laevis and Eleutherodactylus coqui initiate pelvic limb buds before they develop pectoral ones. We studied the expression of Pitx1 in X. laevis and E. coqui to determine if this paired-like homeodomain transcription factor directs differentiation specifically of the hindlimb, or if it directs the second pair of limbs to form, namely the forelimbs. We also undertook to determine if embryonic expression patterns were recapitulated during the regeneration of an amputated limb bud. Pitx1 is expressed in hindlimbs in both X. laevis and E. coqui, and expression is similar in both developing and regenerating limb buds. Expression in hindlimbs is restricted to regions of proliferating mesenchyme.Key words: regeneration, Xenopus laevis, limb bud, Pitx1 protein, specification.

Crystallins during Xenopus laevis free lens formation

1988 ◽  
Vol 197 (3) ◽  
pp. 190-192 ◽  
Author(s):  
Samir Brahma ◽  
Horst Grunz
Keyword(s):  
Xenopus Laevis ◽  
Lens Formation

scholarly journals CHANGES IN CELL FINE STRUCTURE DURING LENS REGENERATION IN XENOPUS LAEVIS

1965 ◽  
Vol 24 (2) ◽  
pp. 211-222 ◽  
Author(s):  
Jane Overton
Keyword(s):  
Fine Structure ◽  
Xenopus Laevis ◽  
Normal Development ◽  
Low Density ◽  
Morphological Complexity ◽  
Lens Fibers ◽  
Lens Regeneration ◽  
Lens Vesicle ◽  
Rough Er ◽  
Two Phases

Changes at the level of cell fine structure have been studied during lens regeneration in the toad, Xenopus laevis, where cornea gives rise to the new lens. The transformation of these cells may be divided into three phases. (1) In the cornea, flattened cells become cuboidal and rough endoplasmic reticulum increases in amount. (2) In the new lens vesicle, cisternae of the rough ER break down into vesicles, smooth-walled vesicles and free ribosomes increase in number, and mitochondria can become enlarged and irregular, then centrally attenuated. Rudimentary cilia form. (3) As new lens fibers form, ribosomes become very numerous and low density fibrous elements and dense clumps appear in the cytoplasm. These phases are accompanied by marked nucleolar changes. The changes during the 3rd phase are similar to changes in the lens during normal development. The first two phases show an unexpected morphological complexity.

Ontogeny and localization of the lens crystallins in Xenopus laevis lens regeneration

Development ◽  
1974 ◽  
Vol 32 (3) ◽  
pp. 783-794
Author(s):  
Samir K. Brahma ◽  
David S. McDevitt
Keyword(s):  
Xenopus Laevis ◽  
Rana Pipiens ◽  
Staining Method ◽  
Early Stage ◽  
Lens Protein ◽  
Lens Crystallins ◽  
Lens Regeneration ◽  
Stage 4 ◽  
Indirect Immunofluorescence Staining ◽  
Normal Lens

Ontogeny and localization of the lens crystallins, especially the γ-crystallins were investigated in Xenopus laevis lens regenerating system by the ‘indirect’ immunofluorescence staining method. Antibodies directed against Rana pipiens γ-crystallin antigen were used for the detection of this crystallin; the validity of such an experiment has been shown in a previous report. To detect total lens proteins we used X. laevis anti-total lens protein antibody. The regenerates were staged according to Freeman (1963) and the first positive reaction with both the two antisera was observed in an early stage-4 regenerate . The site of theimmunofluorescence reaction was nearly identical in both, suggesting that γ-crystallinsare one of the first, if not the first of the lens crystallins to appear during lens regeneration. The secondary fibres, when developed, showed less immunofluorescence than the primary fibres with R. pipiens anti-γ crystallin antibody, though the reaction was intense in the secondary fibres with X. laevis anti-total lens protein antibody. The intensity and distribution of immunofluorescence increased with the growth of the lens. With the R. pipiens anti-γ crystallin antibody, the lens epithelium did not show any immunofluorescence reaction at any stage of lens regeneration. With X. laevis anti-total lens protein antibody, the epithelium showed an immunofluorescence reaction earlier than in the normal lens development. With the two antisera we used, we did not observe any immunofluorescence outside the lens tissue.

An immuno-fluorescent study of lens regeneration in larval Xenopus laevis

Development ◽  
1965 ◽  
Vol 13 (2) ◽  
pp. 171-179
Author(s):  
John C. Campbell
Keyword(s):  
Xenopus Laevis ◽  
Cell Layer ◽  
Morphological Changes ◽  
Posterior Wall ◽  
Corneal Tissue ◽  
Lens Regeneration ◽  
Small Clump

It is well known that several species of amphibia, especially those of the genus Triturus, can regenerate a lens after removal of the original lens from the eye. In most of these species the regenerate develops from the iris (Reyer, 1954), but in larval Xenopus laevis (Overton &Freeman, 1960; Freeman & Overton, 1961, 1962; Freeman, 1963; Campbell, 1963) and possibly in early embryonic stages of Hynobius unnangso (Ikeda, 1936, 1939) the regenerating lens can be formed from corneal tissue. The morphological changes associated with regeneration of the lens from the cornea in X. laevis have been fully described by Freeman (1963), who has shown that the regenerate develops from the inner cell layer of the outer, or ectodermal, cornea, appearing initially as a small clump of cells in the midpupillary region. This aggregate organizes into a vesicle, from the posterior wall of which the primary lens fibres are formed.

scholarly journals Role of the hypoxia response pathway in lens formation during embryonic development of Xenopus laevis

FEBS Open Bio ◽  
2013 ◽  
Vol 3 (1) ◽  
pp. 490-495 ◽  
Author(s):  
Kazunobu Baba ◽  
Taichi Muraguchi ◽  
Susumu Imaoka
Keyword(s):  
Embryonic Development ◽  
Xenopus Laevis ◽  
Hypoxia Response ◽  
Lens Formation

scholarly journals Down-Regulation of Nucleosomal Binding Protein HMGN1 Expression during Embryogenesis Modulates Sox9 Expression in Chondrocytes

2006 ◽  
Vol 26 (2) ◽  
pp. 592-604 ◽  
Author(s):  
Takashi Furusawa ◽  
Jae-Hwan Lim ◽  
Frédéric Catez ◽  
Yehudit Birger ◽  
Susan Mackem ◽  
...  
Keyword(s):  
Chromatin Remodeling ◽  
Chromatin Immunoprecipitation ◽  
Chondrogenic Differentiation ◽  
Nuclear Protein ◽  
Basal Layer ◽  
Cell Types ◽  
Limb Bud ◽  
Wild Type ◽  
Sox9 Expression

ABSTRACT We find that during embryogenesis the expression of HMGN1, a nuclear protein that binds to nucleosomes and reduces the compaction of the chromatin fiber, is progressively down-regulated throughout the entire embryo, except in committed but continuously renewing cell types, such as the basal layer of the epithelium. In the developing limb bud, the expression of HMGN1 is complementary to Sox9, a master regulator of the chondrocyte lineage. In limb bud micromass cultures, which faithfully mimic in vivo chondrogenic differentiation, loss of HMGN1 accelerates differentiation. Expression of wild-type HMGN1, but not of a mutant HMGN1 that does not bind to chromatin, in Hmgn1 −/− micromass cultures inhibits Sox9 expression and retards differentiation. Chromatin immunoprecipitation analysis reveals that HMGN1 binds to Sox9 chromatin in cells that are poised to express Sox9. Loss of HMGN1 elevates the amount of HMGN2 bound to Sox9, suggesting functional redundancy among these proteins. These findings suggest a role for HMGN1 in chromatin remodeling during embryogenesis and in the activation of Sox9 during chondrogenesis.

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