Biosynthesis of a fluorescent protein with extreme pseudo-Stokes shift by introducing a genetically encoded non-natural amino acid outside the fluorophore.

A novel kind of fluorescent protein relying on the intramolecular interplay between two different fluorophores, one of chemical origin and one of biological origin, was developed. The fluorescent non-natural amino acid l-(7-hydroxycoumarin-4-yl)ethylglycine was site-specifically incorporated into the recombinant enhanced cyan fluorescent protein (eCFP) at a permissible surface position ∼20 Å away from the protein fluorophore using amber suppression in Escherichia coli with an engineered cognate Methanococcus jannaschii tRNA synthetase. The resulting eCFP(Cou) exhibited almost quantitative intramolecular Förster resonance energy transfer (FRET) between its two fluorophores, showing brilliant cyan emission at 476 nm upon excitation in the near-UV at 365 nm (a wavelength easily accessible via conventional laboratory UV sources), in contrast to its natural counterpart. Thus, this fluorescent protein with unprecedented spectroscopic properties reveals an extreme apparent Stokes shift of ∼110 nm between the absorption wavelength of the coumaryl group and the emission wavelength of eCFP.

Temba glaucoma study: a population-based cross-sectional survey in urban South Africa.

OBJECTIVE: To determine the prevalence and features of glaucoma in an urban South African black population. DESIGN: Random sampling cross-sectional population survey. PARTICIPANTS: Black residents of Temba, North West Province, South Africa, age > or =40 years. MAIN OUTCOME MEASURES: Automated visual field testing and detailed, standardized slit-lamp examination were attempted on all subjects. Glaucoma was diagnosed by use of the scheme proposed by the Working Group for Defining Glaucoma of the International Society of Geographical and Epidemiologic Ophthalmology on the basis of evidence of end-organ damage. RESULTS: Of 1120 subjects, 839 (74.9%) were examined. The age- and gender-adjusted prevalence of glaucoma of all types was 5.3% (95% confidence interval [CI], 3.9%-7.1%). Primary open-angle glaucoma (POAG) was the most common glaucoma diagnosis, with an adjusted prevalence of 2.9% (95% CI, 1.9%-4.3%). Secondary glaucoma occurred with an adjusted prevalence of 2.0% (95% CI, 1.2%-3.3%). Exfoliative glaucoma was responsible for 16% of all glaucoma cases. The prevalence of primary angle-closure glaucoma was 0.5% (95% CI, 0.13%-1.2%). Of all subjects with glaucoma, 58% were blind in at least one eye. The prevalence of all types of glaucoma increased with age. Of subjects with POAG, 87% had not been previously diagnosed. CONCLUSIONS: The prevalence of glaucoma in this South African population was higher than that found in white populations, and most cases were undiagnosed and untreated. Glaucoma is a major cause of blindness in this population.