Recent studies in Xenopus egg extracts indicate that the small G protein Ran has a central role in spindle assembly and nuclear envelope reformation. We determined Ran localization and dynamics in cells during M phase. By immunofluorescence, Ran is accumulated on the chromosomes of meiosis-II-arrested Xenopus eggs. In living cells, fluorescently labeled Ran associated with the chromosomes in Xenopus and remained associated during anaphase when eggs were artificially activated. Fluorescent Ran associated with chromosomes in mouse eggs, during meiotic maturation and early embryonic divisions in starfish, and to a lesser degree during mitosis of a cultured mammalian cell line. Chromosomal Ran undergoes constant flux. From photobleach experiments in immature starfish oocytes, chromosomal Ran has a koff of ∼0.06 second-1, and binding analysis suggests that there is a single major site. The chromosomal interactions may serve to keep Ran-GTP in the vicinity of the chromosomes for spindle assembly and nuclear envelope reformation.
Interviews with Biologists @ 100 conference speakers
Explore our interviews with keynote speakers from the Biologists @ 100 conference, hosted to celebrate our publisher’s 100th anniversary, where we discuss climate change and biodiversity with Hans-Otto Pörtner and Jane Francis, health and disease with Charles Swanton and emerging technologies with Manu Prakash and Jennifer Lippincott-Schwartz.
Introducing our new Associate Editors
In this Editorial, JCS Editor-in-Chief Michael Way welcomes five new Associate Editors to the JCS team. These Associate Editors will expand our support for the wider cell biology community and handle articles in immune cell biology, proteostasis, imaging and image analysis, plant cell biology, and stem cell biology and modelling.
The spatial choreography of mRNA biosynthesis
In their Review, André Ventura-Gomes and Maria Carmo-Fonseca detail the latest research progress and technological advancements that are helping to unlock how nuclear organisation underpins control of gene transcription and pre-mRNA splicing.
JCS-FocalPlane Training Grants
Early-career researchers - working in an area covered by JCS - who would like to attend a microscopy training course, please apply. Deadline dates for 2025 applications: 6 June 2025 (decision by week commencing 28 July 2025) and 5 September 2025 (decision by week commencing 20 October 2025).
The emerging roles of the endoplasmic reticulum in mechanosensing and mechanotransduction
In their Review, Jonathan Townson and Cinzia Progida highlight recently emerging evidence for a role of the endoplasmic reticulum in enabling a cell to sense and respond to changes in the extracellular mechanical environment.
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