Pierre Haas on Volvox inversion

Average shapes of Volvox inversion

Figure 4 from Haas et al. 2018. Average shapes of Volvox globator embryos for 10 stages of inversion (red lines), obtained from N = 22 overlaid and scaled embryo halves (lines in shades of blue on the left) and corresponding standard deviation shapes (shaded areas on the right).

One of my search alerts turned up a blog post about Volvox inversion, “Upside Down and Inside Out: Inversion in Volvox.” The author wasn’t identified at the top, but by the third paragraph it was clear that the post was written by someone with a deep familiarity with the subject:

In order to be able to swim, the colony must therefore turn itself inside out through a hole at the top of the cell sheet. This process is called inversion, and proceeds in different ways (type-A and type-B inversion) in different species. (It is not clear why Volvox evolved to have its flagella on the inside after cell division: the closely related alga Astrephomene divides into spherical colonies without the need for inversion.

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Volvox at microscopesandmonsters

Check out Martyn Kelly’s blog post about Volvox from a pond in England:

The annual Algal Training Course in Durham always has a field trip out to Cassop Pond, a small pond at the foot of the Permian Limestone escarpment in County Durham that has featured in a few of my posts over the years (see “A return to Cassop”).  This year, the group came back with some samples from the pond’s margins bearing a suspension of green dots just visible to the naked eye which, when examined under the microscope, turned out to be the colonial green alga Volvox aureus.

There’s more, including some lovely micrographs, at https://microscopesandmonsters.wordpress.com/2019/07/17/the-intricate-life-of-a-colonial-alga/.

Volvox rousseletii in Japan

A few years back, I invited Dr. Hisayoshi Nozaki to visit the University of Montana, and to my surprise, he came. In fact, five Japanese researchers came to Missoula for the better part of a week: Dr. Nozaki, Dr. Noriko Ueki, Dr. Osami Misumi, and two undergraduate researchers. We found a speciesVolvox capensis, which had previously only ever been found in South Africa, in Ninepipe Reservoir (about an hour north of Missoula).

Now Ryosuke Kimbara and colleagues have reported another apparent long-distance traveller. In a new paper in PLoS One, they report finding Volvox rousseletii, previously reported only in Africa, in Lake Sagami in Japan. Volvox rousseletii is a member of the group of species known as Volvox section Volvox (also sometimes referred to as Euvolvox), which includes the largest species (in terms of cell number) and evolved independently of the other species in the genus Volvox.

Kimbara Fig. 1

Figure 1 from Kimbara et al. 2019. Light microscopic features of asexual spheroids in culture of Volvox rousseletii strain v-sgm-17 from Lake Sagami, Japan. (A) Mature spheroid showing daughter spheroids (d). (B-D) Part of spheroids. (B) Top view of individual sheaths (asterisks) of somatic cells stained with methylene blue. (C) Top view of somatic cells with thick cytoplasmic bridges (b). (D) Side view of elongate-ellipsoidal, anterior somatic cell with stigma (s) and pyrenoid (p) in the chloroplast. (E) Developing embryo just after inversion, showing gonidia (g) of the next generation.

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Why carteri?

It’s embarrassing, really. I’ve been studying Volvox and its relatives for 15 years now, and until today I couldn’t have told you who the most famous member of the group, Volvox carteri, was named for. Sure, I know Colemanosphaera is named for Annette Coleman, Volvox ferrisii for Patrick Ferris, and Volvox kirkiorum (“of the Kirks”) for David and Marilyn Kirk, but that’s because they were all named after I started studying Volvox.

But do you recall…the most famous algae of all?

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Reminder: early bird registration for Volvox 2019 ends soon

Volvox 2019 logo

If you’re planning to go to the Fifth International Volvox Conference, it’s time to get a move on. Early bird registration and, more importantly, abstract submission end Saturday. Registration is open (at a slightly higher rate) until July 13, but if you want to present a poster or talk, the June 1 deadline applies.

The meeting is July 26-28 in Tokyo and includes a July 29 excursion to the NIES microbial culture collection and the National Museum of Nature and Science.

Reminder: tomorrow is the deadline for the Kato Memorial Bioscience Foundation travel fellowship

¥50,000 is ¥50,000! Applications for travel fellowships from the Kato Memorial Bioscience Foundation for the Fifth International Volvox Meeting are due tomorrow. These fellowships are to help non-Japanese students and postdocs travel to Tokyo for the meeting. ¥50,000 is around $500, a pretty good return for an easy application. Answer a few questions, send an email, and your trip could be $500 cheaper:

Applicants are required to submit a pdf file of the completed application form (download here) to Volvox2019 Office (E-mail: volvox2019 (at) gmail.com)

The Royal Society of Biology deadline is also coming up soon (March 1).

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Say hello to Volvox zeikusii!

Volvox zeikusii

Figures 13-20 from Nozaki et al. 2019*. Light microscopy of female strain of Volvox zeikusii Nozaki. Abbreviations: c, cytoplasmic bridges; d, daughter spheroid or developing embryo; e, egg; i, individual sheath; p, pyrenoid; s, stigma.
Figs 13–19. Asexual spheroids. Fig. 13. Optical section of spheroid. Scale bar = 50 μm. Fig. 14. Optical section of spheroid stained with methylene blue. Scale bar = 50 μm. Fig. 15. Front view of somatic cells showing cytoplasmic bridges. Scale bar = 20 μm. Fig. 16. Front view of somatic cells showing individual sheaths of the gelatinous matrix stained with methylene blue. Scale bar = 20 μm. Fig. 17. Lateral optical section of somatic cells positioned in anterior region of spheroid. Scale bar = 20 μm. Fig. 18. Surface view of somatic cells positioned in anterior region of spheroid. Scale bar = 20 μm. Fig. 19. Surface view of newly formed daughter spheroid. Scale bar = 50 μm. Fig. 20. Sexual female spheroid. Scale bar = 200 μm.

Hisayoshi Nozaki and colleagues have discovered a new species of VolvoxVolvox zeikusii. Or more accurately, they have discovered new strains of an old species and decided that some of the old strains with that name are something else.

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