ABSTRACT
Photo-sensitive liposomes have been studied for a few decades and various photo-sensitive triggers have been developed so far. This review offers an overview of the different photo-triggering mechanisms for controlled pulsatile content release from liposomes, which have the potential of finding clinical applications as intelligent drug delivery systems.
Subject(s)
Liposomes/chemistry , Photosensitizing Agents/chemistry , Azo Compounds/chemistry , Cholesterol/chemistry , Drug Delivery Systems , Humans , Liposomes/radiation effectsABSTRACT
The ultrastructures of male meiocytes in tobacco, onion and lily were studied to elucidate the interaction between cytoplasmic channels (CCs) and plastids. Before meiosis, the male sporogenous cells had identically thickened cell walls (CWs) traversed by typical plasmodesmata (PDs). After entering meiosis, their CWs became uneven in thickness and 80-500nm aperture CCs were formed. Simultaneously, plastids or plastid-like bodies (PLBs) differing in size and morphology assembled at one or both ends of the CCs. These plastids and PLBs commonly orientated their sharper ends to face the CCs and were co-orientated on the axial line crossing the CC. Such pairs of plastids were often interconnected through the CC by thin (50-100nm) threads emanating from their membranes. Sometimes, plastids or PLBs extended directly from one side of a CW to the other, forming a bridge via the CC. In some cases, several plastids formed bridges between cells via one common CC. This is the first report that clearly demonstrates an intercellular continuum of, or communication between, plastids in male plant meiocytes.
