Membranous tubular system in R-cells of decapod hepatopancreas investigated using electron-opaque tracers

Summary Ultrastructural studies of the hepatopancreatic R-cells of Palaemonetes zariquieyi revealed a basal tubular network. Tannic acid and lanthanum nitrate techniques established the presence of numerous infoldings of the basal and lateral plasma membranes that constitute the tubular system. Lipoprotein-like particles were detected inside this system. The contrast of these particles was increased by the osmium-thiocarbohydrazide-osmium (OTO) method. The ultrastructure of the membranous tubular system displays several morphological variants: (a) the tubular membranous system is curved and branched, with a regular reticular aspects, and is often associated with smooth endoplasmic reticulum (SER); (b) the basal and lateral plasma membranes exhibit shallow invaginations that are curved, and (c) the invaginations of the plasma membrane form a membranous branching system with a similar morphology to that of the SER. The possible intervention of the membranous tubular system in exchange processes with the haemolymph is discussed.     

Levels of Ambrosia pollen in the atmospheric spectra of Catalan aerobiological stations

Ambrosia pollen is known as an importantallergen in North America, and more recently in someEuropean countries. From 1989 to 1995, the Ambrosia pollen levels detected at the stationsmonitored by the Aerobiological Network of Catalonia(Xarxa Aerobiològica de Catalunya, XAC) wereinsignificant. In 1996, a considerable althoughtemporary increase in the concentration of this pollenwas detected in the atmosphere over Girona, Barcelona,Bellaterra, Manresa, and Tarragona. Most of the Ambrosia pollen collected in 1996 was concentrated ina single day. Its appearance on that day wasattributed to long range transportation, caused byunusual conditions of atmospheric circulation, fromthe Lyon region in France where the species isabundant. This is the only day where concentrations ofAmbrosia pollen that may be dangerous to humanhealth have been reached. Ambrosia coronopifolia is the most abundantspecies of the genus in Catalonia, and although rare,its expansion is favoured by the fact that it growsthrough rhizomes and sprouts easily. It is, therefore,important to monitor the growth of its population andthe release of its pollen in order to predict theappearance of pollen levels that may precipitateallergic symptoms.