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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New Volvocalean phylogeny

My postdoc makes fun of me for having a lousy memory. Not long ago she showed me a paper about microRNAs, and I said I hadn’t read it. She responded, “Yes you have; you blogged about it!” The other day we were discussing the use of antibiotics to prevent bacterial contamination, and I said I thought I might have done that at one time. She told me I had, it was ampicillin, and the concentration.

I’ve been blogging for nearly four years now, and I’ve published well over 400 posts. So I’ve learned that before I sink a bunch of time into writing a new blog post, it’s worth a quick search to make sure I’m not going to repeat myself. When a new paper from Takashi Nakada and colleagues popped up in my Google Scholar alerts, I didn’t immediately realize that I had already written about it. That post was mainly about a new analysis by Thomas Pröschold and colleagues, with the Nakada trees serving as a point of comparison. The new paper is worth its own post, though.

A group of researchers from Keio University have published a new analysis of evolutionary relationships among green algae in the order Volvocales. Takashi Nakada, Yudai Tsuchida, and Masaru Tomita inferred relationships using one nuclear gene and five chloroplast genes.

Nakada et al. 2019 graphical abstract

Graphical abstract from Nakada et al. 2019 showing Chlamydomonas pila as sister to the multicellular volvocine algae (Tetrabaena, Gonium, Volvox).

Previously, I focused on the monophyly of the multicellular volvocine algae, i.e. the Tetrabaenaceae, Goniaceae, and Volvocaceae (TGV). The multigene analysis shown above supports monophyly, although the support values for the critical node are not shown (meaning that the Bayesian posterior probability is <0.90 and the bootstrap proportions are <50%). Similarly, the new phylogeny doesn’t do much to resolve the backbone relationships within the Volvocaceae. There are differences from previous analyses that would be important if true, specifically in the positions of Volvox globator (the sole representative of Volvox section Volvox) and of Yamagishiella (which appears as part of an isogamous clade rather than sister to the anisogamous/oogamous Eudorina/Pleodorina/(most) Volvox clade). Neither of these differences is well supported, though, which is typical; most published phylogenies provide poor support for these relationships.

Nakada et al. 2019 Fig. 2

Figure 2 from Nakada et al. 2019. Bayesian phylogenetic tree of core-Reinhardtinia based on combined 18S-atpB-psaA-psaB-psbC-rbcL gene sequences. Corresponding posterior probabilities (≥0.90; left) and bootstrap proportions (≥50%) from maximum likelihood (middle) and neighbor-joining (right) analyses are shown next to the branches. Branch lengths and scale bars represent the expected number of nucleotide substitutions per site. Metaclades (MC; 1.00 posterior probabilities).

The main point of the new paper, though, is the close relationship between the multicellular volvocine algae and Chlamydomonas pila. The critical node for this relationship is is supported by a high Bayesian posterior probability (1.00) but crappy bootstrap values (55% for maximum likelihood and <50% for neighbor joining). The authors did do some analyses with fewer taxa to test this relationship, and those trees did have better support, but they also changed other relationships.

Correctly identifying the closest unicellular relative of the multicellular volvocine algae is critical for reconstructing the first steps in the transition to multicellular life. This is far from the first time that other species of Chlamydomonas and some of Vitreochlamys have been implicated. I’m not aware of any previous phylogeny that includes Chlamydomonas pila, but Chlamydomonas debaryana (for example) is usually closer when it is included.

I wouldn’t say that the evolutionary relationships in this group are fully settled at this point; the particulars vary among authors, depending on the gene(s) analyzed, and even depending on the method of phylogenetic inference. Even the monophyly of the multicellular species has been called into question, though I think it’s definitely too early to be confident in that conclusion. Right now it seems that Chlamydomonas pila is the best contender for the sister species to the multicellular clade, and almost certainly a closer relative to Volvox and co. than Chlamydomonas reinhardtii. As the authors point out, this makes C. pila a good candidate for whole-genome sequencing. The closer a relative to the multicellular group we can find, the better we can resolve which changes are specific to the multicellular clade.

 

Stable links:

Nakada, T., Tsuchida, Y. & Tomita, M. 2019. Improved taxon sampling and multigene phylogeny of unicellular chlamydomonads closely related to the colonial volvocalean lineage Tetrabaenaceae-Goniaceae-Volvocaceae (Volvocales, Chlorophyceae). Mol. Phylogenet. Evol. 130, 1–8. doi: 10.1016/j.ympev.2018.09.013

“It was I who destroyed Ehrenberg’s theory”

Volvox globator

Volvox globator Ehrenberg (frontispiece of Julian Huxley’s The Individual in the Animal Kingdom, after A. Lang).

“The Diamond Lens” is a short story published by the Irish writer Fitz-James O’Brien in 1858. It describes the quest of an obsessed amateur microscopist for ever greater degrees of magnification, a goal for which he is willing to go to exceptional lengths. O’Brien was apparently known for mixing scientific themes with mysticism, and “The Diamond Lens” certainly fits this description. I won’t spoil it any further; interested readers can download the story for free (in several formats) from The Gutenberg Project.

As the narrator and protagonist becomes a proficient microscopist, he encounters Volvox:

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Convergence part 7: convergence in Volvox

Last year I wrote a series of posts on convergent evolution and misrepresentations of the history of the concept by proponents of intelligent design including Günter Bechly, Lee M. Spetner, Granville Sewell, and others. I didn’t intend for there to be a two-month gap before the final installment (nor am I sure this is the final installment), but here we are.

To quickly recap, I showed in the first three installments that

The Discovery Institute is producing a revisionist history. To hear them tell it, convergence is something that evolutionary biologists have either barely heard of or that they “invented” or “made up” to hide problems with the tree of life. Convergence “destroys the tree of life,” it “contradict[s] the [modern synthesis],” and it is “quite unexpected” to evolutionary biologists. All of that is a big, stinking pile of wrong. In reality, biologists since Darwin, and including Darwin, have always appreciated the importance of convergence, have written thousands of papers about it, and have included it in every evolutionary biology textbook I’m aware of.

I explained why the argument that convergence is evidence against common descent is daft, and I gave a spectacular example of convergent (or parallel) recruitment of life cycle genes in plants and brown algae. I also promised that I would write about convergent evolution in Volvox, which I have so far failed to do.

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One-stop shopping

I have an Etsy store. I opened it around the time of the Volvox wall art giveaway, and I’ll be the first to admit that it has a limited selection. Exclusive, you might say.

But I can promise you this: it is the world’s foremost source for micrographs of Volvox aureus printed on canvas. It is truly one-stop shopping if the only thing you need is micrographs of Volvox aureus printed on canvas (what else could you need?). If you are in the market for micrographs of Volvox aureus printed on canvas, you need look no further. Unless you can convince Piotr or Katrin to give up theirs, it is probably the only source for micrographs of Volvox aureus printed on canvas.

Volvox aureus

Volvox aureus by me

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Sola cube Micro Volvox

A soon to be former postdoc gave me one of these as a gift. It is gorgeous; the two-dimensional pictures really don’t do it justice.

Volvox carteri

Sola Cube Micro Volvox

The many strange yet intriguing forms of the microorganism, which we could not see through our daily lives, can now be put in front of our eyes with Sola cube Micro. Sola cube Micro, is a three-dimensional portrait of the microorganism, laser crystal engraved into a high transparency optical glass cube. We have worked with graphic designer to create the three-dimensional models of the portraits, by using accurate microscope photos. The two dimensional view through the microscope can now appear in three-dimensional form in front of your eyes. Enjoy the moment of gazing upon the mysterious beauty giving by the wonder of nature, with Sola cube Micro.

The spinning algae
Volvox carteri

A type of freshwater colonial green algae. The root of the name “Volvox” comes from the word volvo, meaning, “to roll” in Latin, as it spins around while it swims through the habitant. Photosynthesis can occur through the chloroplasts. The spheroid body contains two thousand somatic cells on the surface, and each cell is attached with two flagella, which pushes the body onward. Sixteen parts of gonidia grows within the main body as “the daughter Volvox” and break through the maternal colonial to form new lives. It is suggested that the unicellular organism that was relative to Chlamydomonas evolved into multicellular organism, that is, Volvox since about fifty million years ago.

Material
High transparency optical glass

Size and weight
2.0” D × 2.0” W × 2.0” H / 300g

The Sola Cube Micro collection is an eclectic set, including a radiolarian, a heliozoan, a tardigrade egg, and a phage, but as yet no Chlamydomonas.

Updates to the Volvox carteri Wikipedia page

The last time I looked at the Volvox carteri page on Wikipedia, it was pretty sad:

V carteri

Volvox carteri Wikipedia page as of December 12, 2018.

That was it; just a short intro and a section on sexual reproduction. I also had an undergraduate researcher, Sophia Sukkestad, who needed an end of semester project. I thought that if she worked on the V. carteri page, she’d learn a bit about Volvox, gain some familiarity with the relevant literature, and improve this resource for everyone.

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Volvox: a colony of cells

In 1950, a young assistant professor at Princeton University published an essay about Volvox in Scientific American, “Volvox: a colony of cells.” The essay touches on several themes that will be familiar to regular readers of Fierce Roller, including cellular differentiation, inversion, and what it means to be an individual.

The author was John Tyler Bonner, whose (much) more recent work I’ve written about previously (“Chance favors the minute animalcule: John Tyler Bonner on randomness“).

John Tyler Bonner

John Tyler Bonner, ca. 1957. Image from the Guggenheim Foundation.

Among many other contributions, Bonner was a pioneer in the development of the social amoeba (or cellular slime mold) Dictyostelium discoideum as a model system for multicellular development and cell-cell signaling. A member of the National Academy of Sciences and a fellow of the American Association for the Advancement of Science, he has published over twenty books and mountains of peer-reviewed papers.

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