This exists: DJ Volvox.
DJ Volvox
Volvox has been pushing the sound and spirit of underground dance culture since 2006. Her sensitive and energetic sets have made her a favorite among party devotees. No matter the situation she captures the crowd with everything from raw acid and EBM-flavored techno, to dreamy sensual deep house.
We should invite her to play Volvox 2017! I wonder if she projects Knut Drescher’s videos during her sets.
Volvocine taxonomy is in a sorry state. Most nominal genera, and some nominal species, are almost certainly polyphyletic. More than once, I’ve been asked during a talk, “Why is Volvox scattered all over the tree?”
Fig. 2A from Herron et al. 2010. The traits characteristic of the genus Volvox—asexual forms with >500 cells, only a few of which are reproductive, and oogamy in sexual reproduction—have arisen at least three times independently: once in the section Volvox (represented by V. globator, V. barberi, and V. rousseletii), once in V. gigas, and once or possibly twice in the remaining Volvox species. Branch shading indicates maximum-parsimony reconstruction (white = absent, black = present, dashed = ambiguous). Pie charts indicate Bayesian posterior probabilities at selected nodes. Numbers to the left of cladograms indicate log-Bayes factors at selected nodes: positive = support for trait presence, negative = support for trait absence. Interpretation of log-Bayes factors is based on Kass and Raftery’s (1995) modification of Jeffreys (1961, Theory of probability. 3rd edn. Oxford Univ. Press, Oxford, UK.): 0 to 2, barely worth mentioning; 2 to 6, positive; 6 to 10, strong; >10, very strong. Boldface numbers following species names indicate Volvox developmental programs following Desnitski (1995).
Antonie van Leeuwenhoek by Jan Verkolje. Public domain image from Wikimedia Commons.
Trying to find some background on Van Leeuwenhoek’s discovery of Volvox, I came across the following on Wikipedia:
Despite the initial success of Van Leeuwenhoek’s relationship with the Royal Society, this relationship was soon severely strained. In 1676, his credibility was questioned when he sent the Royal Society a copy of his first observations of microscopic single-celled organisms. Previously, the existence of single-celled organisms was entirely unknown. Thus, even with his established reputation with the Royal Society as a reliable observer, his observations of microscopic life were initially met with both skepticism and open ridicule.[12]
In a session chaired by Ray Goldstein, we heard about recent advances in the biophysics of Volvox and Chlamydomonas. Over the last decade or so, Volvox has proven to be an experimentally tractable model system for several questions in hydrodynamics and flagellar motility. Volvox colonies can be grown in large numbers (even by physicists!), clonal cultures have relatively little among-colony variation, and they are large enough to be manipulated in ways that most single-celled organisms can’t. Furthermore, their simple structure accommodates the kind of simplifying assumptions physicists are fond of, leading Kirsty Wan (among others at the meeting) to refer to them as “spherical cows.”
In a series of papers, Douglas Brumley and colleagues have explored flagellar dynamics in Volvox carteri. Amazingly, these studies have shown that the synchronized beating of V. carteri‘s ~1000 pairs of flagella is entirely due to hydrodynamic coupling. In other words, in spite of the apparent high degree of coordination among the flagella of separate cells within a colony, no actual coordination among cells takes place. Synchronization emerges from indirect interactions mediated by the liquid medium. An elegant demonstration of this is shown in Brumley et al.’s 2014 eLife paper, in which somatic cells were physically separated from a colony and held at various distances from each other. Despite there being no direct physical connection between the cells, they beat synchronously when close together, with a phase shift that increased with increasing cell to cell distance:
This is taking much longer than I ever expected; hopefully I can get through blogging about Volvox 2015 before registration opens for Volvox 2017!
The final session on day 1 (August 20) was chaired by Aurora Nedelcu from the University of New Brunswick. Dr. Nedelcu’s introduction emphasized some of the basic questions in evolutionary biology, aside from the origins of multicellularity and sex, on which volvocine research has provided insights: the evolution of morphological innovations, the relative importance of cis-regulatory changes vs. protein-coding changes, kin vs. group selection as competing explanations for the evolution of altruism, the evolution of soma and of indivisibility, the genetic basis of cellular differentiation, and the role of antagonistic pleiotropy (my hastily scribbled notes seem to say “antagonistic pleiotropy of olsl.” Is that supposed to be rls1? This is the cost of waiting too long to write. Maybe Aurora can clarify.).
Ray Goldstein‘s working (!) replica of Antonie van Leeuwenhoek’s microscope.
At the start of the Development session, I asked for a show of hands of people who self-identify as developmental biologists. About four went up. That’s not quite fair, since there’s some ambiguity in the question (primarily? exclusively?), but my point was that what all of us who are interested in the evolution of multicellularity study is the evolution of development. In fact, it might fairly be said that the origin of multicellularity is the origin of development.
One of the most studied aspects of Volvox development is the differentiation of its 2000 or so cells into two types: a few (usually 12-16) large reproductive cells (germ) and the rest small, biflagellate cells that provide motility (soma). The main genes controlling this differentiation have long been known, but the details of how they work are still being worked out.
Erik Hanschen (left) with Cristian Solari, David Smith, and Jillian Walker
We spent Wednesday afternoon sampling some ponds around Cambridge, looking for Volvox and related algae. Dr. Hisayoshi Nozaki, whose lab has described a substantial proportion of the known species, led the effort, but somehow we failed to locate our quarry.
Thomas Pröschold checking an algae-filled pond.
I believe that sex is one of the most beautiful, natural, wholesome things that money can buy.
–Steve Martin
Volvox, and the volvocine algae in general, are well known as a model system for the evolution of multicellularity and cellular differentiation, but they are also an outstanding model for the evolution of sex and mating types. Volvocine algae are facultatively sexual, with haploid vegetative colonies reproducing asexually through mitosis but occasionally entering a sexual cycle that usually results in a diploid, desiccation-resistant zygote or ‘spore.’ Most of the small colonial species and unicellular relatives are isogamous, that is, the gametes are of equal size. Nevertheless, each species has two self-incompatible mating types, usually designated as ‘plus’ and ‘minus.’ In some of the larger species, the gametes have diverged into a small, motile form that we call sperm and a large, often immotile form that we call eggs. Across the eukaryotic domain, it is gamete size, not form of genitalia, fancy plumage, or receding hairline, that define males and females.
The volvocine algae span a wide range of mating systems, making them a useful (and I think underutilized) system for comparative studies of the evolution of sex. As I’ve already mentioned, both isogamous (equal-sized gametes) and oogamous (sperm and eggs) species exist, and there is good reason to suspect that oogamy has evolved independently in two separate lineages:
Isogamy and oogamy (Kirk 2006. Curr. Biol., 16:R1028.)
Figure 5 from van Leeuwenhoek 1700. “I thought convenient to get drawn one such before-mentioned particle, with the particles inclosed within it, as fig. 5 by E F sheweth.”
I usually try to comment on recent papers, but this time I’m going to go back a bit. More than a bit, really: 315 years, to what, as far as I know, is the first published report of Volvox (Van Leeuwenhoek, A. 1700. Part of a Letter from Mr Antony van Leeuwenhoek, concerning the Worms in Sheeps Livers, Gnats, and Animalcula in the Excrements of Frogs. Phil. Trans. Roy. Soc. London, 22:509–518). You know it’s old when half of the s’s look like f’s:
