It is well established that high concentrations of sugar in the lens of the eye eventually lead to fiber cell destruction and cataracts. In these studies the decrease in crystallin mRNAs was quantified as a result of influx of high concentrations of galactose into the lens of rats. The alpha A-, alpha B1-, and gamma-crystallin mRNA concentrations were assessed in normal lens and in lens undergoing development of sugar cataracts by northern blot and in situ hybridization methods. In a normal, 28-day-old lens, alpha A-crystallin mRNA accumulated to high levels throughout the fiberplasm, and alpha B-crystallin mRNA was present at low levels in epithelial cells, with increased expression in elongating epithelial and fiber cells. The beta B1-crystallin mRNA was distributed to about the same grain density throughout the fiberplasm but at significantly lower levels than alpha A-crystallin mRNA. The gamma-crystallin mRNA first emerged in the terminally differentiated fiber cell, with insignificant amounts detected in the elongating epithelial and fiber cells at the bow. Measurements of hybridization levels on the same RNA population isolated from a single lens showed that in the controls, alpha A-crystallin mRNA comprised about ten times the level of alpha B-crystallin mRNA and twice the level of beta B1- and gamma-crystallin mRNAs. In the cataractous lens the rate of decrease in the concentrations of alpha A-, alpha B- and beta B1-crystallin mRNAs was the same; the decrease in gamma-crystallin mRNA was far more severe. By 20 days of feeding of galactose, at the age of 48 days, gamma-crystallin mRNA diminished to about 9% of the control levels, alpha A-crystallin mRNA to 49%, alpha B-crystallin mRNA to 55%, and beta B1-crystallin mRNA to 65%. In the normal lens, at 48 days of age, the levels of alpha A-, alpha B-, and beta B1-crystallin mRNAs showed no significant changes; the gamma-crystallin mRNA level decreased significantly, to about 70% of the day-28 level, the time at which galactose feeding began. Overall, these data suggest that the loss in crystallin mRNAs in response to the development of galactose cataracts follows this order of decline: gamma greater than alpha B greater than alpha A greater than beta B1.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTA Method for the Hybridization of Nucleic Acid Molecules at Low Temperature*James Bonner, Grace Kung, and Isaac BekhorCite this: Biochemistry 1967, 6, 12, 3650–3653Publication Date (Print):December 1, 1967Publication History Published online1 May 2002Published inissue 1 December 1967https://pubs.acs.org/doi/10.1021/bi00864a005https://doi.org/10.1021/bi00864a005research-articleACS PublicationsRequest reuse permissionsArticle Views292Altmetric-Citations94LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEnrichment of selected active human gene sequences in the placental deoxyribonucleic acid fraction associated with tightly bound nonhistone chromosomal proteinsGary L. Norman and Isaac BekhorCite this: Biochemistry 1981, 20, 12, 3568–3578Publication Date (Print):June 9, 1981Publication History Published online1 May 2002Published inissue 9 June 1981https://pubs.acs.org/doi/10.1021/bi00515a041https://doi.org/10.1021/bi00515a041research-articleACS PublicationsRequest reuse permissionsArticle Views22Altmetric-Citations16LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts
To develop and characterize a new model of galactose-induced cataract formation in young, 3- to 4-week-old Hartley guinea pigs.Experimental animals were fed 50% galactose in powdered guinea pig chow containing 0.5 g ascorbate/kg diet. Control animals were fed normal powdered guinea pig chow (0.5 g ascorbate/kg diet). Lenses from all animals were subjected to photo-slit-lamp examination, light microscopic analysis, and high-pressure liquid chromatography (HPLC) analysis of polyol content.Photo-slit-lamp examination indicated initial opacities in equatorial subcapsular region between 3 and 5 days in all galactose-fed animals (20/20); opacities progressed toward the anterior pole when diet was extended to 14 days. Histologic analysis of the equatorial changes confirmed progressive cataract formation consisting of small intra-fibrillar vacuoles in the pre-equatorial region (3 days), an increased number of enlarged and coalesced vacuoles (6 days), and progressive tissue swellings with cellular disruption and signs of epithelial multilayering (14 days). The anterior epithelium showed increased cell height and swelling after 3 days of the galactose diet. HPLC analysis of lens tissue indicated progressive accumulation of galactitol, 18 mM after 3 days, which plateaued to about 30 mM between 6 and 14 days. The level of myo-inositol dropped from a control value of 2.8 +/- 0.7 mM to 1.5 +/- 0.7 mM after 3 days, and was nearly undetectable after 14 days of the galactose diet.The current study suggests that the guinea pig model may serve as a valuable new tool to study sugar-induced cataract formation and to characterize the early morphologic and biochemical events in cataractogenesis.
Thiazolidine-4-carboxylic acid (TZCA) was used to inhibit the incorporation of proline into rat liver ribosomes in a cell-free system. It was found that TZCA was incorporated into ribosomes via a pathway similar to that of proline. The coding polynucleotide for this incorporation was a homo-polymer of cytidine. t-RNA-TZCA-S35 was also isolated, and this presented further evidence that TZCA-S35 was incorporated into ribosomes following the formation of t-RNA-TZCA-S35. Hence, these experiments show that TZCA may be used as a competitive inhibitor to the incorporation of proline into ribosomes in a cell-free system.
Previous work from this laboratory has suggested that swollen nucleated fiber cells can survive in mature galactose-cataracts. Evidence for this observation was derived from analysis on the in vitro translation products of mRNA isolated from normal lens and lens undergoing development of galactose-cataracts. Additional studies on the abundance of a fiber cell specific gene product (MP26 mRNA) in both normal and cataractous lens mapped out gene response to: (1) differentiation of epithelial cells to fiber cells, (2) levels of this differential gene activity and its anatomical location in initiation and maturation of galactose-cataracts, and (3) distribution of MP26 mRNA in fibers of normal and cataractous lens. The results from these studies demonstrated that mRNA subsistence in lens undergoing osmotic cataract development might be an indication of occurrence of mechanisms responsible for the reversibility of that type of cataracts. Presumably, reversibility requires propagation and maintenance of the total population of lens specific mRNAs, as our data suggests.
