Embryology

Becoming from Aeon Video on Vimeo. Watch a single cell become a complete organism in six pulsing minutes of timelapse. A film by Jan van Ijken More about the life form portrayed.

And, it turns out, they must: Zebrafish aren’t just surrounded by liquid, but turn liquid – in part – during their development. As the zebrafish embryo develops from a ball of cells to a fully-formed fish, a region of the embryo switches its phase from viscous to liquid in a process known as fluidity transition. Such fluidity transition has long been speculated to exist in living matter, but is described for the first time to occur in a living organism in a study published today in Nature Cell Biology. The study was carried out by the group of Carl-Philipp Heisenberg at the Institute of Science and Technology Austria, with first author and Postdoc Nicoletta Petridou, and together with the group Read More ›

This series of videos from McDole et al. shows the development of a mouse embryo, captured using adaptive light-sheet microscopy, and highlights cell division (part A), cell movements (part B) and tissue dynamics (parts C, D) during embryogenesis. Paper. McDole, K., Guignard, L., Amat, F., Berger, A., Malandain, G., Royer, L.A., Turaga, S.C., Branson, K., and Keller, P.K. (2018). In Toto Imaging and Reconstruction of Post-Implantation Mouse Development at the Single-Cell Level. Cell. 175. (paywall) Hat tip: Evolution News and Science Today:

At her blog, Oscillations, Suzan Mazur reports on the lecture series Simons Center for Geometry and Physics has been hosting at Stony Brook University, on Nonequilibrium Physics in Biology: Among the more interesting presenters is Kim Sneppen, a professor of complex systems and biophysics at Neils Bohr Institute in Copenhagen, who addresses the diversity of shapes in the biological world. Sneppen says, “We are basically all doughnuts” and describes how we go from a sphere to a torus in his talk titled: “Theoretical Tool Bridging Cell Polarities with Development of Morphologies.” Suzan Mazur, “Kim Sneppen, Simons Center Talk: “We are basically all doughnuts”” at Oscillations Mazur discusses his approach to embryology and along the way mentions Stuart Pivar, an early Read More ›

From Suzan Mazur at Oscillations, With the ramping up of investigations in various parts of the world into the mechanics of biology, I’ve decided to post my conversation with Institut Curie biophysicist Emmanuel Farge on the role of mechanics in reprogramming the embryo [2010], relating to his work first published in the scientific literature in 2003, which was well received by the science establishment. … Emmanuel Farge:Exactly. Because you need the gene expression to have the germ-band extension. Then after you need the germ-band extension to have the expression of Twist at the anterior pole, which is mechanically induced. What I’m saying is that you always are in a situation where you cannot say that mechanics is more important than genetics Read More ›

From Jonathan Wells at ENST, looking at a variety of systems, including the bioelectric code: Regional differences in cells and embryos can be specified in other ways besides localization of RNAs in the cortex. Two of those ways have been studied in great detail: the “sugar code” and the “bioelectric code.” Most proteins in living cells — including those in membranes — are chemically bonded to carbohydrates called “glycans” (from the Greek word for “sweet”). The nucleotides in DNA are linked together end-to-end in a linear molecule, so DNA sequence information is one-dimensional. In living cells, the subunits in proteins (with a few exceptions) are also linked in a linear chain. But glycans can be linked together in complex three-dimensional Read More ›

From Suzan Mazur at Oscillations: The mechanics of morphogenesis is something European scientists, in particular, seem to find intriguing. However, physical biology is an approach many classical biologists in America have had a difficult time in the past understanding as well as accepting, as evidenced by vociferous attacks in the blogosphere on scientists working in that area. Fortunately, this is changing with America’s new generation of scientists, with project support from organizations like the Simons Foundation, and with publicly funded research in Europe that continues to explore along those lines. French scientists, in particular, have been central to the inquiry into the mechanics of shape in developmental biology. An inspiring example is the current work of Jean-Léon Maître, who is Read More ›

It’s too cool a concept for accuracy to matter. Further to “Remember the ‘developmental hourglass’? Well, not so fast,” Jonathan Wells writes to point out that vertebrate embryos more closely resemble each on another than do their adult forms only if one carefully cherry-picks the desired stages, which are long after the beginning of development. In Zombie Science, he writes, — In 2008, University of Chicago historian Robert Richards published a book defending Haeckel against charges of fraud. According to Richards, Haeckel’s drawings were no less accurate than those of his contemporaries, including the people who criticized him. 37 Cambridge historian Nick Hopwood also defended Haeckel against the fraud charge in a 2015 book that included several pages criticizing Icons of Evolution as Read More ›