Eye lens development and γ crystallins in Discoglossus pictus (Anura)

Summary The ontogeny and localization of the crystallins in Discoglossus pictus lens development has been determined. Using antibody specific for amphibian crystallins in the immunofluorescence technique, it was found that crystallins first appear in primary lens fibre cells in the lens rudiment, and continue to be restricted to the fibre area as lens development progresses. Thus the role of crystallins as indicators of a differentiated state remains constant in amphibian evolution, having been demonstrated in the most archaic anuran superfamily, as well as in others more recently evolved.This research was largely accomplished during the tenure of a fellowship from the European Molecular Biology Organization to D. S. McDevitt, and was partially supported by Biomedical Research Support Grant RR 546414 to D. S. McDevitt.The authors are grateful to Prof. W. J. van Doorenmaalen for use of the laboratory facilities; and to the Hubrecht Laboratory, International Embryological Institute, Utrecht, The Netherlands, for the gift of live D. pictus eggs. We thank Miss C. M. J. Stuifsand for the normal histology and Mr Th. Hulskes for the illustrations.     

Retrospective immunofluorescence of specific antigens in stained and balsam embedded sections of the developing amphibian lens

A modification of the indirect immunofluorescent method is proposed for the detection of specific proteins in sections of the developing amphibian lens that were attached using egg albumin, stained and embedded into Canada balsam.     

Filaments of the vertebrate lens

Summary Filaments of an average diameter of 10–12 nm have been identified in the eye lens fibre cells of representative species of each vertebrate order. These filaments presumably serve a cytoskeletal role in the lens fibre cells.This study was supported by research grant Ey 0141 of the National Institutes of Health, Bethesda, Maryland, USA.     

Chain-proteins of the vertebrate lens

Some lens proteins exist in a chain-like form in the vertebrate lens fibre cells. They consist of globular proteins arranged on a filamentous backbone.     

Retrospective immunofluorescence of specific antigens in stained and balsam embedded sections of the developing amphibian lens

Summary A modification of the indirect immunofluorescent method is proposed for the detection of specific proteins in sections of the developing amphibian lens that were attached using egg albumin, stained and embedded into Canada balsam.Acknowlegments. We thank Dr G. G. Gauze and Dr Olga Hoperskaya for their help in translation of this paper.     

Chain-proteins of the vertebrate lens

Summary Some lens proteins exist in a chain-like form in the vertebrate lens fibre cells. They consist of globular proteins arranged on a filamentous backbone.This study was supported by research grant EY-01417 of the National Institutes of Health, Bethesda, Maryland, USA.     

Transgenic mice carrying chimeric or mutated type III intermediate filament (IF) genes

Mice carrying chimeric, truncated or mutated genes encoding intermediate filament (IF) proteins type III do not show any detectable severe pathology. However, upon (over)expression of the transgene in the eye lens all animals develop lens opacification (cataract). At the cellular level the loss of visual acuity is preceded by interference with the terminal differentiation of lens fibre cells, plasma membrane damage, distorted assembly of the IF cytoskeleton and perturbation of the cytoskeleton-membrane complex. The degree of expression is paralleled by the extent of the damages. Received 4 November 1996; accepted 15 November 1996     

Polypeptides of the lens fibre cell intracellular matrix

Summary The cytoskeletal proteins of the vertebrate lens fibre cell comprise polypeptides ranging in mol.wt from 43,000 to 250,000 daltons. The main intermediate filament polypeptide of the pickerel, Northern frog, chick, bovine, and human lens has a mol.wt of 54,000 daltons. Peptide analysis revealed that the chick 54,000 dalton protein was more similar to the bovine protein than to the pickerel protein.Supported by grants EY 01417 (H. Maisel) and HD-06390 (J.C. Brown, University of Virginia, Charlottesville) from the National Institutes of Health, U.S.P.H.S.     

A note on the mechanism of action of UV-irradiation of amphibian embryos

The actions on amphibian embryos of UV-irradiation, exposure to Li+ or exposure to ouabain show interesting parallels with their effects on spontaneous release at the presynaptic terminals of the neuromuscular junction. It is suggested that these treatments serve to raise intracellular Ca2+ ([Ca2+]i) in these examples, and that UV-promoted abnormalities in embryogenesis are a consequence of changes in [Ca2+]i at critical stages in development.     

Effects of gamma irradiation on dermal equivalents in vitro

Summary Dermal equivalents (DE), collagen lattices, were produced in vitro and used as a model for studying the possible role of a pure population of fibroblasts in post-radiotherapeutic dermal fibrosis. Single doses of gamma irradiation induced a partial inhibition of the collagen lattice retraction and of protein synthesis. The collagen production was less inhibited than was synthesis of non-collagen protein, which resulted in an increase of the relative amount of collagen synthesized by irradiated fibroblasts. These data suggest that gamma irradiation might be able to select some fibroblast clones able to produce increasing amounts of collagen. This selection process could be involved in the development of tissue fibrosis after therapeutic radiation.     

A note on the mechanism of action of UV-irradiation of amphibian embryos

Summary The actions on amphibian embryos of UV-irradiation, exposure to Li⁺ or exposure to ouabain show interesting parallels with their effects on spontaneous release at the presynaptic terminals of the neuromuscular junction. It is suggested that these treatments serve to raise intracellular Ca²⁺ ([Ca²⁺ _i) in these examples, and that UV-promoted abnormalities in embryogenesis are a consequence of changes in [Ca²⁺]_i at critical stages in development.     

Effects of gamma irradiation on dermal equivalents in vitro

Dermal equivalents (DE), collagen lattices, were produced in vitro and used as a model for studying the possible role of a pure population of fibroblasts in post-radiotherapeutic dermal fibrosis. Single doses of gamma irradiation induced a partial inhibition of the collagen lattice retraction and of protein synthesis. The collagen production was less inhibited than was synthesis of non-collagen protein, which resulted in an increase of the relative amount of collagen synthesized by irradiated fibroblasts. These data suggest that gamma irradiation might be able to select some fibroblast clones able to produce increasing amounts of collagen. This selection process could be involved in the development of tissue fibrosis after therapeutic radiation.     

Similarities between sodium channels in excitable membranes and in epithelia

Summary The inhibitory effects of the pyrazine derivative, amiloride, on sodium transport in an amphibian epithelium has been studied as a function of pH. It is concluded that the charged (guanidinium) group interacts with a negatively charged acid grouping in the membrane. Similarities between sodium channels in excitable membranes and epithelia are highlighted.     

Similarities between sodium channels in excitable membranes and in epithelia.

The inhibitory effects of the pyrazine derivative, amiloride, on sodium transport in an amphibian epithelium has been studied as a function of pH. It is concluded that the charged (guanidinium) group interacts with a negatively charged acid grouping in the membrane. Similarities between sodium channels in excitable membranes and epithelia are highlighted.     

An immunoreactive peptide in milk contains bombesin-like bioactivity

Parallel in vitro bioassays using rat uterus and guinea pig large intestine tissues specific for the bombesin family of peptides, demonstrated that the bombesin-like peptides present in bovine milk can produce a dose-related response similar to bombesin and litorin. The bioactivity of this type of milk peptide appeared to be approximately 20-50% as active as the amphibian peptides. These data support the proposal that a bombesin immunoreactive peptide in milk contains bombesin bioactivity.     

L'action du chlorure de lithium et du sulfocyanure de sodium sur la viscosité de la nucléohistone et des extraits d'embryons d'Amphibiens

Summary (1) LiCl increases the viscosity and decreases the rigidity of nucleohistone; NaSCN has opposite effects.(2) The effects of LiCl and NaSCN on the viscosity of amphibian embryo extracts, as observed byRanzi and his coworkers, seem to be due to the action of these salts on nucleohistone.     

The reduction of genic activity in the tetraploid amphibianOdontophrynus americanus is not due to loss of ribosomal DNA

Summary Genic activity in tetraploid members of the amphibian speciesOdontophrymus americanus is reduced to that of diploid ones. Loss of ribosomal genes, a mechanism suggested by others as a means of decreasing genetic activity, could be ruled out. The diploids and the tetraploids have almost identical proportions of their genomes complementary to (28s+18s) ribosomal RNA.     

Elimination and metabolism of dimethylnitrosamine (DMN) by Xenopus laevis and other amphibians

The elimination of (14C)-DMN after i.p. injection into Xenopus was measured, as was the metabolism in vitro of (14C)-DMN by liver from Xenopus and 9 other amphibian species. In view of its rapid elimination from the body and low rate of metabolism by Xenopus liver in vitro, DMN is unlikely to be toxic or carcinogenic in Xenopus.     

Unexpected features of the interaction between individual primary afferents and spinal motoneurones.

Simultaneous intracellular recording from spinal motoneurone and dorsal root fibres afferent to it in the isolated amphibian cord revealed a specific correlation between the slow spontaneous depolarizing activity in motoneurones and primary afferents.