The cell that isn't: New technique captures division of membrane-less cells

January 18, 2013
The cell that isn’t: New technique captures division of membrane-less cells

This may look like yet another video of a dividing cell, but there's a catch. You are looking at chromosomes (red) being pulled apart by the mitotic spindle (green), but it's not a cell, because there's no cell membrane. Like a child sucking an egg out of its shell, Ivo Telley from the European Molecular Biology Laboratory (EMBL) in Heidelberg, Germany, removed these cellular 'innards' from a fruit fly embryo, at a stage when it is essentially a sac full of membrane-less 'cells' that divide and divide without building physical barriers to separate themselves from each other.

"It's the first time we can study ongoing cell division without the , and that means we can physically manipulate things," says Telley, "so we can uncover the physical forces involved, and see what are the constraints."

The new technique is described in detail today in Nature Protocols, and has already led Telley and colleagues to a surprising discovery. They found that, although successive divisions fill the embryo with more and more material, leaving less and less space for each spindle, and spindles become smaller as the embryo develops, simply squeezing the 'cell' into tighter quarters doesn't make it produce a smaller spindle.

Combined with the approaches commonly used in fruit fly studies, the scientists believe their new technique will help to unravel this and other mysteries of how a cell becomes two.

The work, which started in Thomas Surrey's lab at EMBL, was carried out by Telley and Imre Gáspár in Anne Ephrussi's lab at EMBL. Surrey is now at Cancer Research UK.

Explore further: Researchers work out the mechanics of asymmetric cell division

More information: A single Drosophila embryo extract for the study of mitosis ex vivo. Telley, I.A., Gáspár, I., Ephrussi, A. & Surrey, T. Nature Protocols, Advanced online publication on 17 January 2013. DOI: 10.1038/nprot.2013.003

Spindle assembly and chromosome segregation rely on a complex interplay of biochemical and mechanical processes. Analysis of this interplay requires precise manipulation of endogenous cellular components and high-resolution visualization. Here we provide a protocol for generating an extract from individual Drosophila syncytial embryos that supports repeated mitotic nuclear divisions with native characteristics. In contrast to the large-scale, metaphase-arrested Xenopus egg extract system, this assay enables the serial generation of extracts from single embryos of a genetically tractable organism, and each extract contains dozens of autonomously dividing nuclei that can be prepared and imaged within 60–90 min after embryo collection. We describe the microscopy setup and micropipette production that facilitate single-embryo manipulation, the preparation of embryos and the steps for making functional extracts that allow time-lapse microscopy of mitotic divisions ex vivo. The assay enables a unique combination of genetic, biochemical, optical and mechanical manipulations of the mitotic machinery.

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1 / 5 (4) Jan 18, 2013
The cytoplasm is a gel, and being a gel means that the cell membrane is not necessary to either hold the cell together, or even to maintain the observed ionic gradients. Gels do both of those things without the need for a cell membrane. There are polymers out there which exhibit behavior that bears a striking resemblance to the on/off switching of ions that is typically inferred as the behavior of a pump within cell membranes. If cell biologists are willing to entertain the notion that the pump and channel hypothesis might be in error (that they don't actually maintain these ionic gradients), then an entirely new biological paradigm is possible. See the work of Gerald Pollack, which builds upon the prior work of Gilbert Ling. Pollack has already demonstrated that this approach to biology can yield incredibly simple explanations for phenomena like inflammation, the movement of red blood cells through the smallest capillaries, photosynthesis and even cloud formation.
5 / 5 (1) Jan 19, 2013
Yeah only thing problematic with your comment is...that we know these channels exist. And we know how they function. Sooooooo...what?
5 / 5 (1) Jan 19, 2013
Syncytial cells are a late eukaryote evolution, and they are always enclosed by a membrane. This is a barrier to the environment, but also keeps the necessary cellular mechanism in place, which encompasses pores and pumps necessary for small cells.

While embryonal syncytial embryos are feed by the egg nutrients, no one has observed membrane-less life. Maybe it is short term possible, but our biology doesn't swing that way.
not rated yet Jan 29, 2013
Absolutely wonderful work! Congrats!

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