Waltzing Volvox

I can’t believe I haven’t already blogged about this, but if I have it isn’t turning up in my searches. Ravi Balasubramanian’s preprint about “flocking” behavior in Volvox barberi mentioned that

V[olvox] carteri is capable of using fluid forces created by flagellar beating to form waltzing pairs.

He’s referring to a 2009 paper by Knut Drescher and colleagues in Physical Review Letters. Drescher and colleagues analyzed the physics that cause Volvox colonies to enter a hydrodynamically bound state in which two or more spheroids orbit each other in close proximity:

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Alternative patterns of explanation for major transitions

The Major Transitions in Evolution Revisited

One reason to study green algae is because they can teach us something about the evolution of multicellularity. A number of related species in the Volvocalean family form a gradation of complexity between single-celled and simple multicellular organisms. The members of this family of algae differ in size, the number of cells they produce, and whether or not there is a split between germline and somatic cells. This split is thought to be central to understanding how a new level of individuality has evolved. — Calcott 2011, p. 39.

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Extreme variation in male Volvox carteri from Taiwan

Nozaki et al. 2018 Fig. 1 A-D

Figure 1 a-d from Nozaki et al. 2018. Light microscopy of asexual spheroids in Taiwanese strains of Volvox carteri f. nagariensis. a Surface view of a spheroid showing undivided gonidia (G). 2016‐tw‐nuk‐6‐1. b Optical section of a spheroid in (a) with gonidia (G). c Surface view of spheroid. Note no cytoplasmic bridges between somatic cells. 2016‐tw‐nuk‐6‐1. d Surface view of spheroid showing individual sheaths of the gelatinous matrix. Stained with methylene blue. 2016‐tw‐nuk‐8‐1. e Optical section of gonidium. 2016‐tw‐nuk‐6‐1. f, g Pre‐inversion plakea or embryo (E) showing gonidia (G) of the next generation outside. 2016‐tw‐nuk‐8‐1.

Most of what we know about the developmental genetics of Volvox comes from the Eve strain of Volvox carteri forma nagariensis, which was collected by Richard Starr from Kobe, Japan in 1967. Eve is the strain that David Kirk and colleagues used for most of their experiments and from which most of the important developmental mutants are derived.

It’s natural, then, to think that Eve is representative of V. carteri f. nagariensis and that what’s true for Eve is generally true for this forma. Recent work from Hisayoshi Nozaki and colleagues shows that, at least in one respect, this is a bad approximation.

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This should be interesting

I’m pretty sure I got a scammer to send a cashier’s check to the Federal Trade Commission. I despise Craigslist scammers (all scammers, really) ever since I moved to Vancouver. My dad had driven up with me, all the way from Tucson with Heidi in his lap, and we were staying in a hotel downtown while I tried to find a place to live.

Dad and Heidi

1600 miles in a Miata with a 35-pound dog in his lap. My dad is a hero.

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Volvox barberi “flocks”

Balasubramanian Fig 3 A&B

Figure 3 A&B from Balasubramanian 2018. (a) V. barberi flock where 56 colonies gathered over several minutes and rotated coherently and rapidly in the culture well. (b) Schematic of flock in panel a.

At the Fourth International Volvox Meeting in St. Louis, a student from Harriton High School in Rosemont, Pennsylvania presented a talk and a poster on “flocking” behavior in Volvox barberi. Now a preprint describing his work is available on bioRxiv.

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