Eye lens development and gamma crystallins in Discoglossus pictus (Anura).

The ontogeny and localization of the gamma crystallins in Discoglossus pictus lens development has been determined. Using antibody specific for amphibian gamma crystallins in the immunofluorescence technique, it was found that gamma 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 gamma 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.     

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.     

The effect of chloroquine upon the developing lens

Applied to the developing lens of the 14-day-old chick embryo, in organ culture conditions, chloroquine prevented the elongation of the primary lens fibres, destroyed the equatorial ones and provoked vacuolisation and/or destruction in the epithelial cells.     

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     

Preparation of specific antiserum against Rana esculenta pre-alpha lens crystallin.

Specific antiserum against Rana esculenta lens pre-alpha crystallin was prepared in a rabbit by injecting antigen-antibody precipitate of this crystallin obtained from immunoelectrophoresis of esculenta total soluble lens proteins against homologous antiserum.     

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.     

Seasonal variations in mitosis in the frog: a field study.

Field studies have shown that there is a seasonal variation in mitosis of lens and corneal epithelium (high in May and June, low during the rest of the year). This phenomenon can be reproduced in the laboratory by temperature manipulation. The response in the lens depends on the presence of the pituitary gland while the corneal one seems to be independent of it.     

N-cadherin detected in the membrane fraction of lens fiber cells

N-cadherin was identified as a glycoprotein present in the fiber cell membranes of frog, chick, bovine, rabbit and human lenses. The molecular size of N-cadherin varies with the species. Homogenization of the chick lens in the presence of Ca2+ resulted in a decrease in the concentration of N-cadherin. This suggests that the lens contains a Ca2(+)-activated protease which can act on N-cadherin.     

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.     

Potential aldose reductase inhibitors: 1,2,4-triazolidine-3,5-diones and 2-(3,4,5-trimethoxybenzoyl)-4,4-diethyl-3,5-isoxazolidinedione .

1,2,4-Triazolidine-3,5-diones and the 3,5-isoxazolidinedione were observed to be potent inhibitors of rat lens aldose reductase activity. In vivo in streptozotocin-diabetic rats, selected agents at 20 mg/kg/day, orally for 21 days reduced significantly the sorbitol levels of rbc, lens and sciatic nerves, suggesting that these derivatives may have some usefulness to treat clinical complications of diabetes mellitus.     

Potential aldose reductase inhibitors: 1,2,4-triazolidine-3,5-diones and 2-(3,4,5-trimethoxybenzoyl)-4,4-diethyl-3,5-isoxazolidinedione

1,2,4-Triazolidine-3,5-diones and the 3,5-isoxazolidinedione were, observed to be, potent inhibitors of rat lens aldose reductase activity. In vivo in streptozotocin-diabetic rats, selected agents at 20 mg/kg/day, orally for 21 days reduced significantly the sorbitol levels of rbc, lens and sciatic nerves, suggesting that these derivatives may have some usefulness to treat clinical complications of diabetes mellitus.     

N-cadherin detected in the membrane fraction of lens fiber cells

Summary N-cadherin was identified as a glycoprotein present in the fiber cell membranes of frog, chick, bovine, rabbit and human lenses. The molecular size of N-cadherin varies with the species. Homogenization of the chick lens in the presence of Ca²⁺ resulted in a decrease in the concentration of N-cadherin. This suggests that the lens contains a Ca²⁺-activated protease which can act on N-cadherin.     

Lens regeneration from the dorsal iris inEurycea bislineata,the two-lined salamander

Summary Following lens removal from the eye of adultEurycea bislineata, the northern (USA) 2-lined salamander, it was found that this salamander has the capacity for lens regeneration. Its widespread distribution and high percentage of regenerative success suggests it as a suitable organism for the study of this differentiative phenomenon.This research was supported by N.I.H. grant EY-02534 from the National Eye Institute. We thank S.M. DiRienzo for excellent technical assistance.     

Carbohydrate composition of the human cataractous lenses

Summary Specific chemical assays, including carbohydrate, hexosamines and hexuronic acid, were determined on the lens insoluble albumoid. It was noticed that the carbohydrate composition varies with age. The significance of carbohydrate in the lens in discussed.This work was supported by the College of Medicine of the University of Lagos, and financed by the British Council. The work was undertaken at the Department of Chemistry and Applied Chemistry, University of Salford, Salford (England).Special thanks are expressed to Dr L. R. Croft and Prof. G. I. Phillip for their help, support and encouragement throughout this study.     

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.     

Thomas Harriot’s optics,between experiment and imagination: the case of Mr Bulkeley’s glass

Some time in the late 1590s, the Welsh amateur mathematician John Bulkeley wrote to Thomas Harriot asking his opinion about the properties of a truly gargantuan (but totally imaginary) plano-spherical convex lens, 48 feet in diameter. While Bulkeley’s original letter is lost, Harriot devoted several pages to the optical properties of “Mr Bulkeley his Glasse” in his optical papers (now in British Library MS Add. 6789), paying particular attention to the place of its burning point. Harriot’s calculational methods in these papers are almost unique in Harriot’s optical remains, in that he uses both the sine law of refraction and interpolation from Witelo’s refraction tables in order to analyze the passage of light through the glass. For this and other reasons, it is very likely that Harriot wrote his papers on Bulkeley’s glass very shortly after his discovery of the law and while still working closely with Witelo’s great Optics; the papers represent, perhaps, his very first application of the law. His and Bulkeley’s interest in this giant glass conform to a long English tradition of curiosity about the optical and burning properties of large glasses, which grew more intense in late sixteenth-century England. In particular, Thomas Digges’s bold and widely known assertions about his father’s glasses that could see things several miles distant and could burn objects a half-mile or further away may have attracted Harriot and Bulkeley’s skeptical attention; for Harriot’s analysis of the burning distance and the intensity of Bulkeley’s fantastic lens, it shows that Digges’s claims could never have been true about any real lens (and this, I propose, was what Bulkeley had asked about in his original letter to Harriot). There was also a deeper, mathematical relevance to the problem that may have caught Harriot’s attention. His most recent source on refraction—Giambattista della Porta’s De refractione of 1593—identified a mathematical flaw in Witelo’s cursory suggestion about the optics of a lens (the only place that lenses appear, however fleetingly, in the writings of the thirteenth-century Perspectivist authors). In his early notes on optics, in a copy of Witelo’s optics, Harriot highlighted Witelo’s remarks on the lens and della Porta’s criticism (which he found unsatisfactory). The most significant problem with Witelo’s theorem would disappear as the radius of curvature of the lens approached infinity. Bulkeley’s gigantic glass, then, may have provided Harriot an opportunity to test out Witelo’s claims about a plano-spherical glass, at a time when he was still intensely concerned with the problems and methods of the Perspectivist school.     

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.     

Hypophysectomy exerts a radioprotective effect on frog lens

Summary Exposure to X-rays usually causes cataracts in frogs. These cataracts are always preceded by misalignment of the structures called meridional rows (MR). When cell division is completely halted by hypophysectomy, however, irradiation no longer disturbs the orientation of the MR. Since the MR are the structures formed as lens epithelial cells differentiate into lens fibres it is reasonable to propose that radiocataractogenesis depends upon a mitosis-driven formation of pathological fibres from epithelial cells that have been rendered abnormal by exposure to X-rays.This research was supported by: NIH grant No. EY 02492-02 (HR); NIH grant No. EY 02648-02 (BVW).     

Isolation of filaments of the chick lens

A preparation of intermediate filaments isolated from the chicken lens is enriched with a 50,000 dalton polypeptide.     

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.