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Spatial coherence of light inside three-dimensional media. Nat Commun 2021; 12:4199. [PMID: 34234114 PMCID: PMC8263759 DOI: 10.1038/s41467-021-23978-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Accepted: 05/17/2021] [Indexed: 11/26/2022] Open
Abstract
Speckle is maybe the most fundamental interference effect of light in disordered media, giving rise to fascinating physical phenomena and cutting edge applications. While speckle formed outside a sample is easily measured and analysed, true bulk speckle, as formed inside random media, is difficult to investigate directly due to the obvious issue of physical access. Furthermore, its proper theoretical description poses enormous challenges. Here we report on the first direct measurements of spatially resolved intensity correlations of light inside a disordered medium, using embedded DNA strings decorated with emitters separated by a controlled nanometric distance. Our method provides in situ access to fundamental properties of bulk speckles as their size and polarization degrees of freedom, both of which are found to deviate significantly from theoretical predictions. The deviations are explained, by comparison with rigorous numerical calculations, in terms of correlations among polarization components and non-universal near-field contributions at the nanoscale. Light in disordered materials generates rich interference patterns called speckle, whose properties are known only on the outside of a sample. Here, the authors provide direct measurements and understanding of speckle generated inside a material, retrieving fundamental information that remained inaccessible up to now.
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Venditti R, Rega LR, Masone MC, Santoro M, Polishchuk E, Sarnataro D, Paladino S, D'Auria S, Varriale A, Olkkonen VM, Di Tullio G, Polishchuk R, De Matteis MA. Molecular determinants of ER-Golgi contacts identified through a new FRET-FLIM system. J Cell Biol 2019; 218:1055-1065. [PMID: 30659100 PMCID: PMC6400564 DOI: 10.1083/jcb.201812020] [Citation(s) in RCA: 86] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 12/14/2018] [Accepted: 12/18/2018] [Indexed: 01/05/2023] Open
Abstract
ER-TGN contact sites (ERTGoCS) have been visualized by electron microscopy, but their location in the crowded perinuclear area has hampered their analysis via optical microscopy as well as their mechanistic study. To overcome these limits we developed a FRET-based approach and screened several candidates to search for molecular determinants of the ERTGoCS. These included the ER membrane proteins VAPA and VAPB and lipid transfer proteins possessing dual (ER and TGN) targeting motifs that have been hypothesized to contribute to the maintenance of ERTGoCS, such as the ceramide transfer protein CERT and several members of the oxysterol binding proteins. We found that VAP proteins, OSBP1, ORP9, and ORP10 are required, with OSBP1 playing a redundant role with ORP9, which does not involve its lipid transfer activity, and ORP10 being required due to its ability to transfer phosphatidylserine to the TGN. Our results indicate that both structural tethers and a proper lipid composition are needed for ERTGoCS integrity.
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Affiliation(s)
- Rossella Venditti
- Telethon Institute of Genetics and Medicine, Pozzuoli, Italy .,Department of Molecular Medicine and Medical Biotechnology, University of Napoli Federico II, Medical School, Naples, Italy
| | - Laura Rita Rega
- Telethon Institute of Genetics and Medicine, Pozzuoli, Italy
| | | | - Michele Santoro
- Telethon Institute of Genetics and Medicine, Pozzuoli, Italy
| | | | - Daniela Sarnataro
- Department of Molecular Medicine and Medical Biotechnology, University of Napoli Federico II, Medical School, Naples, Italy
| | - Simona Paladino
- Department of Molecular Medicine and Medical Biotechnology, University of Napoli Federico II, Medical School, Naples, Italy
| | - Sabato D'Auria
- Institute of Food Science, Consiglio Nazionale delle Ricerche, Avellino, Italy
| | - Antonio Varriale
- Institute of Food Science, Consiglio Nazionale delle Ricerche, Avellino, Italy
| | - Vesa M Olkkonen
- Department of Anatomy, Faculty of Medicine, FI-00014 University of Helsinki, Helsinki, Finland.,Minerva Foundation Institute for Medical Research, Biomedicum 2U Helsinki, Helsinki, Finland
| | | | | | - Maria Antonietta De Matteis
- Telethon Institute of Genetics and Medicine, Pozzuoli, Italy .,Department of Molecular Medicine and Medical Biotechnology, University of Napoli Federico II, Medical School, Naples, Italy
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