Characterization of a caleosin expressed during olive (Olea europaea L.) pollen ontogeny

<p>Abstract</p> <p>Background</p> <p>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.</p> <p>Results</p> <p>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 <it>in vitro</it>. Moreover, PEGylation experiments supported the structural conformation model suggested for caleosins from seed oil bodies.</p> <p>Conclusions</p> <p>In the olive anther, a caleosin is expressed in both the tapetal and germ line cells, with its synthesis independently regulated. The pollen oil body-associated caleosin is synthesized by the vegetative cell, whereas the protein located on the pollen exine and its coating has a sporophytic origin. The biological significance of the caleosin in the reproductive process in species possessing lipid-storing pollen might depend on its subcellular emplacement. The pollen inner caleosin may be involved in OB biogenesis during pollen maturation. The protein located on the outside might rather play a function in pollen-stigma interaction during pollen hydration and germination.</p

Detection and Quantitation of Olive Pollen Allergen Isoforms Using 2-D Western Blotting

This work was supported by the Spanish Ministry of Science and Innovation (MICINN) (ERDF-cofinanced projects AGL2008-00517, BFU2011-22779 and PIE-200840I186) and the Junta de Andalucía (ERDF-cofinanced projects P2010-CVI5767 and P2010-AGR6274). K. Zienkiewicz thanks the CSIC for providing JAEdoc grant funding.Peer reviewe

Pheophorbide a may regulate Jasmonate signaling during dark-induced senescence

Chlorophyll degradation is one of the most visible signs of leaf senescence. During senescence, chlorophyll is degraded in the multistep pheophorbide a oxygenase (PAO)/phyllobilin pathway. This pathway is tightly regulated at the transcriptional level, allowing coordinated and efficient remobilization of nitrogen toward sink organs. Using a combination of transcriptome and metabolite analyses during dark-induced senescence of Arabidopsis (Arabidopsis thaliana) mutants deficient in key steps of the PAO/phyllobilin pathway, we show an unanticipated role for one of the pathway intermediates, i.e. pheophorbide a Both jasmonic acid-related gene expression and jasmonic acid precursors specifically accumulated in pao1, a mutant deficient in PAO. We propose that pheophorbide a, the last intact porphyrin intermediate of chlorophyll degradation and a unique pathway "bottleneck," has been recruited as a signaling molecule of chloroplast metabolic status. Our work challenges the assumption that chlorophyll breakdown is merely a result of senescence, and proposes that the flux of pheophorbide a through the pathway acts in a feed-forward loop that remodels the nuclear transcriptome and controls the pace of chlorophyll degradation in senescing leaves

MRI diffusion-based filtering: a note on performance characterisation

Frequently MRI data is characterised by a relatively low signal to noise ratio (SNR) or contrast to noise ratio (CNR). When developing automated Computer Assisted Diagnostic (CAD) techniques the errors introduced by the image noise are not acceptable. Thus, to limit these errors, a solution is to filter the data in order to increase the SNR. More importantly, the image filtering technique should be able to reduce the level of noise, but not at the expense of feature preservation. In this paper we detail the implementation of a number of 3D diffusion-based filtering techniques and we analyse their performance when they are applied to a large collection of MR datasets of varying type and quality

WPROWADZENIE DO ZAGADNIENIA TOMOGRAFII W ALGORYTMACH POSTPROCESSINGU DLA REAKTORÓW TYPU TOKAMAK

The collaboration of authors led to implementing advanced and fast systems for diagnostics of plasma content in tokamaks. During the development of systems it is planned to add new functionalities, in particular, the algorithms of tomographic reconstruction to obtain &nbsp;information on three dimensional distribution of plasma impurities. In the article the idea of tomographic reconstruction is introduced and issues of performance and adequate hardware selection are presented.Wieloletnia współpraca autorów przyczyniła się do powstania zaawansowanych, szybkich mechanizmów diagnostyki składu gorącej plazmy tokamakowej. W ramach rozbudowy systemów zamierza wprowadzić się szereg nowych funkcjonalności, w tym algorytmy rekonstrukcji tomograficznej. Pozwoli to na uzyskanie informacji o przestrzennym rozkładzie nieczystości plazmy w reaktorze. Praca przedstawia koncepcję tomografii tego typu oraz przeprowadzona jest dyskusja nad zagadnieniami wydajności i doboru sprzętu

Identification and localization of a caleosin in olive (Olea europaea L.) pollen during in vitro germination

In plant organs and tissues, the neutral storage lipids are confined to discrete spherical organelles called oil bodies. Oil bodies from plant seeds contain 0.6–3% proteins, including oleosins, steroleosins, and caleosins. In this study, a caleosin isoform of ∼30 kDa was identified in the olive pollen grain. The protein was mainly located at the boundaries of the oil bodies in the cytoplasm of the pollen grain and the pollen tube. In addition, caleosins were also visualized in the cytoplasm at the subapical zone, as well as in the tonoplast of vacuoles present in the pollen tube cytoplasm. The cellular behaviour of lipid bodies in the olive pollen was also monitored during in vitro germination. The number of oil bodies decreased 20-fold in the pollen grain during germination, whereas the opposite tendency occurred in the pollen tube, suggesting that oil bodies moved from one to the other. The data suggest that this pollen caleosin might have a role in the mobilization of oil bodies as well as in the reorganization of membrane compartments during pollen in vitro germination

Biología reproductiva del olivo (BRO-EEZ-CSIC)

Trabajo presentado a las III Jornadas Nacionales del grupo de Horticultura de la SECH, celebradas en Sevilla el 6 y 7 de octubre de 2011.Peer reviewe

Microscopy to study plant sexual reproduction

This work has been supported by numerous research projects. Currently active projects include EFDF confunded grants BFU2011-22779 (Ministerio de Economía y Competitividad), P2010-CVI5767, P2010-AGR6274 and P2011-CVI7487 (Junta de Andalucía), and PEOPLE-PIOF-GA-2011-301550 (European Research Council)Peer reviewe