Recombinant aequorin and green fluorescent protein as valuable tools in the study of cell signalling.

Luminous proteins include primary light producers, such as aequorin, and secondary photoproteins that in some organisms red-shift light emission for better penetration in space. When expressed in heterologous systems, both types of proteins may act as versatile reporters capable of monitoring phenomena as diverse as calcium homoeostasis, protein sorting, gene expression, and so on. The Ca(2+)-sensitive photoprotein aequorin was targeted to defined intracellular locations (organelles, such as mitochondria, endoplasmic reticulum, sarcoplasmic reticulum, Golgi apparatus and nucleus, and cytoplasmic regions, such as the bulk cytosol and the subplasmalemmal rim), and was used to analyse Ca(2+) homoeostasis at the subcellular level. We will discuss this application, reviewing its advantages and disadvantages and the experimental procedure. The applications of green fluorescent protein (GFP) are even broader. Indeed, the ability to molecularly engineer and recombinantly express a strongly fluorescent probe has provided a powerful tool for investigating a wide variety of biological events in live cells (e.g. tracking of endogenous proteins, labelling of intracellular structures, analysing promoter activity etc.). More recently, the demonstration that, using appropriate mutants and/or fusion proteins, GFP fluorescence can become sensitive to physiological parameters or activities (ion concentration, protease activity, etc.) has further expanded its applications and made GFP the favourite probe of cell biologists. We will here present two applications in the field of cell signalling, i.e. the use of GFP chimaeras for studying the recruitment of protein kinase C isoforms and the activity of intracellular proteases.

Transpupillary thermotherapy in the management of circumscribed choroidal hemangioma.

PURPOSE: To report a case of circumscribed choroidal hemangioma effectively managed with transpupillary thermotherapy. METHOD: A 53-year-old man affected by extramacular circumscribed choroidal hemangioma had sustained a decline in visual acuity caused by subretinal fluid exudation into the macular area. Multiple attempts at treatment with scatter photocoagulation over the surface of the lesion for several years had been unsuccessful in reducing tumor-related exudation. The patient was examined on referral and underwent a single session of treatment employing transpupillary thermotherapy. The course of the lesion after treatment was documented with fundus photography and ultrasonography. RESULT: Complete atrophy of the choroidal hemangioma with resorption of subretinal fluid was documented over the 6 months after transpupillary thermotherapy, with improvement in visual acuity. CONCLUSION: Transpupillary thermotherapy is an effective alternative to conventional scatter photocoagulation or radiation therapy for precise ablation of circumscribed choroidal hemangioma.