Ehrenberg on Eudorina

Eudorina elegans, from Ehrenberg 1832.

Eudorina elegans, from Ehrenberg 1832.

Eudorina elegans was described by the German biologist Christian Gottfried Ehrenberg in his Lectures at the Academy of Sciences in Berlin in the years 18301836 (Vorträge in der Akademie der Wissenschaften zu Berlin im Jahre 1830-1836). With the help of Google Translate, here’s what he had to say about it (page 17):

I have also found an eye-shaped form in the family of the epigones, or of the mucous, intestinal infusoria, which have a hairy body. This form of infusoria is also undefined, but it is confused by me, and probably by all previous observers, with Pandorina Morum (Volvox Morum Müller); Less accurate observers also thought they were probably Volvox Globator. I found them in the basin of the animal garden in the spring of this year between conferences. It is quite consistent with the same form, as I see from my drawing made in the Ural, that the animal which I, as Pandorina Morum, from Kyschtym, have doubtless listed in my list of the Russian Infusoria, and I am of the opinion that I had at that time only overlooked the unsuspected eye. The body consists of a gelatinous, globule-shaped sphere, in which a certain number of spherical, green-colored animals are enclosed, each showing a beautiful red, round but small eye, and a simple, long, whirling, or supporting eyelash through the water. The whirling is seen very clearly as soon as a fine, turbid substance is added to the water. To this animal, which is one of the most beautiful infusoria, I have given the generic name Eudorina, in consideration of the closely related eyeless genus Pandorina. The only known species I have called Eudorina argus (beautiful green eye ball).

[Read more…]

New review of green algal sex

Hiroyuki Sekimoto from Japan Women’s University has published a review of sexual reproduction in the volvocine algae and in the Charophyte Closterium in the Journal of Plant Research. In addition to a brief description of the Chlamydomonas sexual cycle, it includes a succinct review of the genetics of sex and sex determination. Unfortunately, the article is paywalled, and my inquiry to the author has so far gone unanswered.

Figure 1 from Sekimoto 2017. The life cycle of Chlamydomonas reinhardtii. Vegetative cells (V) di erentiate into mt+ and mt− gametes (G) during nitrogen starvation (−N). Mating types are restricted by mating-type loci (+ and −). When gametes are mixed, the plus and minus agglutinin mol- ecules on their agellar surfaces adhere to each other, and this adhe- sion results in increased intracellular cAMP levels. The signal trig- gers gamete cell wall release and mating-structure activation. Cells then fuse to form binucleate quadri agellated cells. Zygotes with thick cell walls germinate in response to light and nitrogen supple- mentation, and undergo meiosis to release four haploid vegetative cells

Figure 1 from Sekimoto 2017. The life cycle of Chlamydomonas reinhardtii. Vegetative cells (V) differentiate into mt+ and mt− gametes (G) during nitrogen starvation (−N). Mating types are restricted by mating-type loci (+ and −). When gametes are mixed, the plus and minus agglutinin molecules on their flagellar surfaces adhere to each other, and this adhesion results in increased intracellular cAMP levels. The signal triggers gamete cell wall release and mating-structure activation. Cells then fuse to form binucleate quadriflagellated cells. Zygotes with thick cell walls germinate in response to light and nitrogen supplementation, and undergo meiosis to release four haploid vegetative cells.

[Read more…]

Algae porn

I track the #Volvox hashtag on Twitter, which is how I find out about a lot of the off-label uses of the name Volvox, like DJ VolvoxVolvox the ship, and Volvox the art gallery. Every now and then, it even turns up something related to Volvox the little rolling algae. The other day, @QuintaSwinger tweeted the following video with #Volvox:

The Twitter handle is about just what you think it is; apparently volvocine sex puts someone in mind of polyamory. I suppose I can see that: when a sperm packet enters a colony, it gets busy with all the ova. The video was uploaded to YouTube by Dr. Donald Ott from the University of Akron.

I think the algae in the video are not actually Volvox, though. Certainly the still photo at the beginning is Volvox. Probably not section Volvox (too few cells), and probably not Developmental Program 2 (germ cells too small in the one on the lower right). If I had to guess, I’d say V. aureus, but that’s largely a Bayesian bet because they’re so common. Maybe Alexey Desnitskiy or Hisayoshi Nozaki can comment.

The colonies in the video, though, look more like Pleodorina to me. Not P. sphaerica, since the somatic cells are all in the front, but without more information I can’t narrow it down more than that.

Invasive Pleodorina indica in Poland

Figure 3 B-I from Knysak and Żelazna-Wieczorek 2017. Pleodorina indica (Iyengar) H. Nozaki 400x.

Figure 3 B-I from Knysak and Żelazna-Wieczorek 2017. Pleodorina indica (Iyengar) H. Nozaki 400x.

A new paper in Oceanological and Hydrobiological Studies reports a massive bloom of Pleodorina indica in a reservoir in central Poland. Piotr Knysak and Joanna Żelazna-Wieczorek sampled the reservoir on the Olechówka River in Łódź during the summer of 2015 and found that P. indica made up ~95% of the algae collected.

[Read more…]

Pandorina(?) in The Atlantic

In The Atlantic, not in the Atlantic. A new article in The Atlantic is making the rounds on social media, “Scientists Brace for a Lost Generation in American Research.” The article speculates on the likely long-term effects of President Trump’s proposed ~20% cut to the NIH budget. Which is fine, because what has the NIH ever done for us? Okay, there was the whole genetic code thing, plus

[Read more…]

J. S. Huxley part 1: Gonium

Julian Huxley was one of the biologists responsible for the merging of Mendelian genetics and Darwinian evolution in the early 20th century, the modern synthesis. His most influential work was Evolution: The Modern Synthesis, published in 1942. Thirty years earlier, though, he published a book on biological individuality, The Individual in the Animal Kingdom. Thankfully, the copyright on this book has expired, so it is now part of the public domain, and a scanned version is available for free in pdf and epub versions from Google.

Huxley Cover

Any book with Volvox on the cover can’t be all bad!

[Read more…]

Sex change (in Volvox)

Alexey Desnitskiy from Saint Petersburg State University has published a new review of sexual development in the genus Volvox in the International Journal of Plant Reproductive Biology. 

The article includes an up-to-date review of Professor Desnitskiy’s own work describing four developmental “programs” in the various species of Volvox:

[Read more…]

What is a (Volvox) species?

Hisayoshi Nozaki and colleagues have just described some Volvox samples from two lakes and a pond in Japan.

Figure 1A from Nozaki et al. 2016. Volvox sp. Sagami asexual spheroid with daughter colonies (d).

Figure 1A from Nozaki et al. 2016. Volvox sp. Sagami asexual spheroid with daughter colonies (d).

The newly collected strains have a lot in common with another recently described species, Volvox ferrisii, but there are some important differences as well:

…it could be clearly distinguished from all previously described monoecious species of Volvox sect. Volvox by its small number of eggs or zygotes (5–25) in sexual spheroids, with short acute spines (up to 3 μm long) on the zygote walls and elongated anterior somatic cells in asexual spheroids.

In spite of these differences, Nozaki and colleagues stop short of calling the newly collected strains a new species. Why?

[Read more…]

Initiation of cell division in Chlamydomonas

Deborah Shelton and colleagues have published a new article arguing that the reigning model of cell division initiation in Chlamydomonas reinhardtii needs to be revised [full disclosure: Dr. Shelton and I were labmates in Rick Michod’s lab at the University of Arizona]. The evolution of multicellularity almost certainly involved changes in cell cycle regulation; for example, there is good evidence that changes to the cell cycle regulator retinoblastoma were involved in the initial transition to multicellular life in the volvocine algae. So understanding cell cycle regulation is vital for understanding the evolution of multicellularity.

[Read more…]