title: Fluorescence Dynamics in the Endoplasmic Reticulum of a Live Cell: Time-Resolved Confocal Microscopy.
abstract: Fluorescence dynamics in the endoplasmic reticulum (ER) of a live non-cancer lung cell (WI38) and a lung cancer cell (A549) are studied by using time-resolved confocal microscopy. To selectively study the organelle, ER, we have used an ER-Tracker dye. From the emission maximum (λmaxem) of the ER-Tracker dye, polarity (i.e. dielectric constant, ϵ) in the ER region of the cells (≈500 nm in WI38 and ≈510 nm in A549) is estimated to be similar to that of chloroform (λmaxem =506 nm, ϵ≈5). The red shift by 10 nm in λmaxem in the cancer cell (A549) suggests a slightly higher polarity compared to the non-cancer cell (WI38). The fluorescence intensity of the ER-Tracker dye exhibits prolonged intermittent oscillations on a timescale of 2-6 seconds for the cancer cell (A549). For the non-cancer cell (WI38), such fluorescence oscillations are much less prominent. The marked fluorescence intensity oscillations in the cancer cell are attributed to enhanced calcium oscillations. The average solvent relaxation time (<τs >) of the ER region in the lung cancer cell (A549, 250±50 ps) is about four times faster than that in the non-cancer cell (WI38, 1000±50 ps).
authors.affiliation: Department of Physical Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata, 700 032, India), Fax: (91)-33-2473-2805.
authors.forename: Shirsendu
authors.initials: S
authors.lastname: Ghosh
authors.affiliation: Department of Physical Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata, 700 032, India), Fax: (91)-33-2473-2805.
authors.forename: Somen
authors.initials: S
authors.lastname: Nandi
authors.affiliation: Department of Physical Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata, 700 032, India), Fax: (91)-33-2473-2805.
authors.forename: Catherine
authors.initials: C
authors.lastname: Ghosh
authors.affiliation: Department of Physical Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata, 700 032, India), Fax: (91)-33-2473-2805. pckb@iacs.res.in.
authors.forename: Kankan
authors.initials: K
authors.lastname: Bhattacharyya
mesh_terms: D002478:Cells, Cultured; D004721:Endoplasmic Reticulum / Q000737:chemistry* / Q000378:metabolism; D005453:Fluorescence; D005456:Fluorescent Dyes / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D018613:Microscopy, Confocal; D015394:Molecular Structure; D013050:Spectrometry, Fluorescence; D013997:Time Factors
chemical_list: D005456:Fluorescent Dyes
keywords: confocal microscopy; endoplasmic reticulum; fluorescence oscillation; lung cells; solvent relaxation