Sea stars. (Or, picoplankton from the Pacific.) Photo from Daniel Vaulot on Wikimedia Commons.

The oceans of our planet are so immense that it's often difficult to accurately determine what their occupants are up to. A recent paper in Science focuses on picoplankton, the tiniest ocean occupants but also the most widespread. It's a segment of life driven by photosynthesis (in the photo above, all the small orange dots are photosynthetic cyanobacteria). The new study found that the day-light cycle has an effect on more than just the dominant photosynthetic species, however. Non-photosynthetic, heterotrophic microbes also appeared to exhibit differences as a result of available sunlight.

This summary offers a more detailed breakdown.

I read a review article about phage therapy today (citation below*) with the following opening sentence:

The human gut contains approximately 10¹⁵ bacteriophages (the ‘phageome’), probably the richest concentration of biological entities on earth.

Is that claim actually true? They cite this Lepage et al. Gut paper; those folks estimate that 10¹⁴ microorganisms (that is, distinct cells) live in any single human gut. We usually guess that an environment contains at least 10 times as many individual bacteriophage as potential host cells, so 10¹⁵ bacteriophages doesn't seem like a bad estimate. That being said, could there be a more densely-populated reservoir out there? I've seen population counts for chickens as high as 19 billion but I wasn't able to find any estimates of their gut microbiome diversity. We know they're a potential reservoir of pathogens and their population exceeds that of humanity.

Update: I've been thinking about this and realized that the phrase "richest concentration of biological entities" likely refers to a single human gut rather than the sum of all human gut microbiomes and viriomes. I like to think about ecological niches on a grand scale; the total number of different variations in phage genomes is higher when we include every similar environment in the total rather than the contents of just one human gut. My qualms about the superlative remain. I'd suspect that some sewer systems may contain richer, more diverse arrays of phages, and that's without employing much creativity. Could other species on this planet maintain more diverse microbiomes and/or viriomes?



*Dalmasso M, Hill C, Ross RP (2014) Exploiting gut bacteriophages for human health. Trends in microbiology 22: 399–405.

This is the kind of music I listen to while in the lab:

When I'm feeling rushed, I listen to the same thing, just faster. 
(Yes, I made that. My inspiration was several hours of staring at protein interaction networks.)

Power couples

I read about mutualism today. There has been - and continues to be - a long-running debate regarding the evolution of mutualism. The problem has often come down to a lack of evidence: we can be fairly confident that symbiotic mutualism is a real phenomenon but it's not always easy to demonstrate. We also know that many of the best examples of mutualism, such as chloroplasts, are the result of extensive evolution. Can mutualism emerge mutation, given the right circumstances for symbiotic partnerships to emerge?

A recent paper by Horn and Murray and accompanying summary article in Science show how it can happen. It's a neat, simple demonstration which would make a great elementary science class project.

Citation:
Horn EFY, Murray AW (2014) Niche engineering demonstrates a latent capacity for fungal-algal mutualism. Science 345: 94–98.

Gotta keep it clean.

This is what my desktop looked like on December 8, 2003. Yes, I used Kazaa, the Uber of the early 00's (see previous blog entry). Other items of note:

• Matching GUI and Winamp skin. Looks like I was listening to Hybrid - If I Survive. It was probably this remix, actually.
• Fruity Loops Studio 4, the perfect software package for the young, enterprising electronic musician on a severely limited budget.
• A Temporary Desktop Folder. Nothing temporary about it. That's where every document goes.
• Both AIM and Trillian. This version of Trillian crashed every 10 minutes or so.
• I was not as cyberpunk in real life as this desktop may imply.