CRISPR/Cas9 mutagenesis in Volvox

Researchers in Stephen Miller’s lab at the University of Maryland, Baltimore County have successfully used CRISPR/Cas9 to knock out several developmentally important genes in Volvox carteri. CRISPR/Cas9 is a relatively new technology that allows heritable mutations to be introduced into living cells at specific locations within the genome.

This advance was announced in a new paper in The Plant Journal by José A. Ortega-Escalante, Robyn Jasper, and Stephen M. Miller (Jasper and Ortega-Escalante are listed as equal contributors). They were able to transform wild-type V. carteri with inversion-deficient and somatic-regenerator mutations, and they transformed somatic regenerator mutants with a gonidialess (no specialized reproductive cells) mutation.

I have never used CRISPR/Cas9, and I don’t know as much about it as I should, so I’m sure any explanation I gave would be riddled with errors. Here’s someone who seems to know what she’s talking about:

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Convergence part 6: the deepest of deep homologies

You are more closely related to a mushroom than a kelp is to a plant. It’s strange to think about, but it’s true. Kelps seem very plant-like, with their root-like holdfasts, stalk-like stipes, and leaf-like blades. But kelps are brown algae, part of the stramenopile (or heterokont) lineage of eukaryotes, which are very distant from the land plants and their green algal relatives, all of which are within the archaeplastida (the direct descendants of the primary origin of chloroplasts). Mushrooms (fungi) and humans (animals), on the other hand, are both opisthokonts, practically cousins at the scale we’re talking about.

Pawlowski 2013 Fig. 1

Figure 1 from Pawlowski 2013. Deep phylogeny of eukaryotes showing the position of small eukaryotic lineages that branch outside the seven supergroups (modified after Burki et al. 2009; drawings S Chraiti). You are represented by a fish, which at this scale you might as well be.

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Volvox email

I got an email from a science teacher in India. This is the internet being what we thought it would be in the 1990s. I did my best to answer, but feel free to weigh in in the comments.

Dear Matthew,

This is Subhashini, I am a science teacher and a content writer for higher secondary school in India. I have gone through your research papers about Volvox. I still have few questions about Volvox. As I do not want children to get confused need some clarification. I would appreciate if you can help me in answering few questions regarding the same.

Q.1 Is Volvox unicellular, multicellular or colonial organism? Why? (I understand the evolutionary process and the relation of the same but need the explanation about specific cellularity.)

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David Kirk obituary from WUStL

David Kirk

David Kirk. Image from schoolpartnership.wustl.edu.

Washington University in St. Louis’s The Source has published an obituary of Dr. David Kirk, who died November 1, by Myra Lopez:

Kirk, who was an active and passionate member of the university community for nearly 50 years, spent a lifetime teaching developmental biology and researching the evolutionary origins of multicellular organisms. He was internationally known for his research on the spherical green alga known as Volvox carteri.

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Convergence part 5: an embarrassment of riches

In parts onetwo, and three of this series, I showed that some intelligent design proponents have created an alternate history of biological thought, in which evolutionary biologists have only recently discovered that similar traits often appear in distantly related species. I showed that this picture is false, and I gave a sampling of quotes–from Jean-Baptiste Lamarck, Charles Darwin, Ernst Mayr, George Gaylord Simpson, Willi Hennig, and others–demonstrating that evolutionary biologists have recognized that this phenomenon is common for as long as there can reasonably be said to have been evolutionary biologists. In part four I explained why widespread convergence is not evidence against common descent, as some ID proponents have claimed.

Mivart Cover

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Travel grants for Volvox 2019

Volvox 2019 logo

The Fifth International Volvox Conference will be July 26-29, 2019 at the University of Tokyo Hongo campus. For past meetings, generous support from organizations such as the American Genetic Association, the Company of Biologists, Wellcome Trust, and the Phycological Society of America has allowed the organizing committee to award travel fellowships to students and postdocs. It’s not yet clear if that will be the case for next year’s meeting.

Stephanie Höhn has helpfully put together a list of outside travel grants available to students and/or postdocs, along with their deadlines and membership requirements:

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Repost: Message from David Kirk

After last week’s sad news that one of the founding fathers of Volvox research, David Kirk, had passed away, I thought it would be relevant to repost a message he sent a couple of years ago. The modern series of Volvox meetings started in 2011 in Arizona, and we’ve been calling them the First through Fourth International Volvox Conferences, with the Fifth scheduled for July 26-29, 2019. Dr. Kirk wrote in with some interesting historical insight about Volvox meetings that long preceded the current series:

I got an email out of the blue from David Kirk, and I thought some of it would be of interest. Dr. Kirk is one of the biggest names in Volvox research: he carried out much of the developmental genetics that forms the foundation of our field, he literally wrote the book on Volvox evo-devo, and my impression is that most of the PIs currently studying Volvox spent time in his lab as students and postdocs.

VolvoxBookCover

The email was prompted by the meeting review from the 2015 meeting in Cambridge (he liked it, whew! :-D), and he said that he’s looking forward to the 2017 meeting in St. Louis. The email also had a footnote with some interesting information, which I quote here with Dr. Kirk’s permission:

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Convergence part 4: “an epic myth”

I promised in part one of this series that I would show why the argument that convergence is a problem for evolution is daft, and I haven’t really done that. What I’ve done so far is show that the argument includes a false premise, namely that evolutionary biologists have only recently become aware that convergence is widespread.

In parts onetwo, and three, I showed that some intelligent design proponents misrepresent the history of biological thought regarding convergence. They have created an alternate history in which biologists from Darwin to Dawkins were barely aware of convergent evolution, and have only in the last few decades been forced to confront it. Whether this is dishonesty or just bad scholarship, I can’t say, but it is a big, stinking pile of wrong.

But I haven’t really engaged their core argument, a fair paraphrase of which is that convergence, the appearance of similar phenotypes in distantly related species, is evidence against (or even falsifies) common descent. For example, Cornelius Hunter says convergence

…violates the evolutionary pattern. Regardless of adaptation versus constraint explanations, and any other mechanisms evolutionists can or will imagine, the basic fact remains: a fundamental evidence and prediction of evolution is falsified. —2017-05-25

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