Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành y học dành cho các bạn tham khảo đề tài: Characterization of a caleosin expressed during olive (Olea europaea L.) pollen ontogeny | Zienkiewicz et al. BMC Plant Biology 2011 11 122 http 1471-2229 11 122 BMC Plant Biology RESEARCH ARTICLE Open Access Characterization of a caleosin expressed during olive Olea europaea L. pollen ontogeny Krzysztof Zienkiewicz1 2 Agnieszka Zienkiewicz1 3 María Isabel Rodriguez-Garcia1 and Antonio J Castro1 Abstract Background The olive tree is an oil-storing species with pollen being the second most active site in storage lipid biosynthesis. Caleosins are proteins involved in storage lipid mobilization during seed germination. Despite the existence of different lipidic structures in the anther there are no data regarding the presence of caleosins in this organ to date. The purpose of the present work was to characterize a caleosin expressed in the olive anther over different key stages of pollen ontogeny as a first approach to unravel its biological function in reproduction. Results A 30 kDa caleosin was identified in the anther tissues by Western blot analysis. Using fluorescence and transmission electron microscopic immunolocalization methods the protein was first localized in the tapetal cells at the free microspore stage. Caleosins were released to the anther locule and further deposited onto the sculptures of the pollen exine. As anthers developed tapetal cells showed the presence of structures constituted by caleosin-containing lipid droplets closely packed and enclosed by ER-derived cisternae and vesicles. After tapetal cells lost their integrity the caleosin-containing remnants of the tapetum filled the cavities of the mature pollen exine forming the pollen coat. In developing microspores this caleosin was initially detected on the exine sculptures. During pollen maturation caleosin levels progressively increased in the vegetative cell concurrently with the number of oil bodies. The olive pollen caleosin was able to bind calcium in vitro. Moreover PEGylation experiments supported the structural conformation model suggested for .
