SINGEK BLOG: The Virus in a drop of ocean and in a drop of you


Luiz Felipe de Almeida


Electron micrograph of bacteriophages (bacterial viruses) attached to a host cell. Image modified from original by Dr Graham Beards CC BY-SA 3.0

Viruses. They are everywhere. They are the most abundant creatures on the planet. Probably you have heard about them when you get sick at home for a few days or when you watch the news about the next big pandemic. Now, in your body could be around thousands of viruses in some cells of you. Most certainly you don’t like them at all, but give viruses a chance. If there were no viruses, life on our planet would be very different, and maybe you and everyone you know and care about would not exist.

We will back into you later, because now I want you to consider a drop of ocean. In every liter of marine water there is about a billion of viral particles. In fact, in each wave there might be more viruses than there are visible stars in the sky.

But viruses can’t exist by themselves. In order to be active and replicate, that is, produce more viruses, they have to infect a living cell. So in a droplet of marine water there is a billion year old war between cellular organisms and viral organisms. This “microbial war” has profound impacts, for example on our planet’s climate. Some viruses infect algal cells, that is tiny plant-like organisms which also use sunshine to grow. They cause the algae to modify the production of some gases which help to create clouds above the ocean and other gases, such as CO2 which has a significant role in climate change.

There are marine viruses which can even stimulate food production from sunlight, technically called “photosynthesis”, by infecting some kinds of microbes. Some small viruses, called “virophages” help their hosts protecting against other giant viruses. And ultimately, some can even go deeper than that by becoming one with their hosts. By integrating their genetic material into the host DNA, they are blurring the boundary between virus and host cell.

I hope I had convinced you by now that there is much more about viruses than diseases. But how do viruses connect to your own existence? Well, there is a remarkable similarity between proteins that make up the placenta (the structure that protects the embryo inside the womb) and viral envelope proteins. This similarity is unlikely to be due to chance alone. Scientists hypothesise that around 150 million years ago, an integration event of viral DNA into the genome of a mammalian ancestor of ours has occurred, giving rise to the placenta in its current form.

This entangled history between viruses and cells could have allowed placentarians to become the dominant form of life, creating arts, politics, science and controlling our planet. But now that you know more about the viral world and their roles, you may start to ask yourself who really is in control, and if there is a single winner in this billion-year old planetary war, that is still happening right now, in a drop of sea water, or in every drop of you.

About the author

Luiz Felipe de Almeida – ESR 9

I am a Biologist from Brazil (UNISINOS), Master in “Biodiversity and Evolutionary Biology” (UFRJ) and currently a PhD candidate from Université Pierre et Marie Curie – Sorbonne in the Observatoire Océanologique Banyuls-sur-mer working in the group “GENOPHY” with marine microalgae and its bacterial and viral interactions. My SINGEK ESR 9 research project is “Genomic insights into green microalgae and their interactions with viruses and bacteria”.

SINGEK BLOG: Chemical Hammer Needed


Javier Florenza



Different cell covers for 4 different unicellular eukaryotes. Left to right;top to bottom: Coccolithus pelagicus, haptophyte (Richard Lampitt & Jeremy Young, CC BY 2.5) Scenedesmus sp., chlorophycean (Frank Fox, CC BY-SA 3.0 DE) Peridinium willei, dinoflagellate (Picturepest, CC BY 2.0) Eupodiscus radiatus, diatom (Mary Ann Tiffany, CC BY 2.5)

The information containing the building plan of all organisms and its proper function is stored in the genetic material, the DNA. It somehow defines as well the kind of creature carrying it, and also its uniqueness. That means our DNA makes us humans yet it also is the basis for the differences between you and your friends and neighbours.

And this genetic material, where is it located? In the brain? In the liver? In the bone marrow, maybe? The answer is: it is actually everywhere in your body. We are essentially a large collection of cells kept together, a number bigger than 100 times the cars in the world. For each of us. And, between many other things, each one contains our entire genome. We are not able to see the DNA though, because cells are microscopic containers of life. All the huge amount of information we need to become ourselves is thus stored in a very tiny compartment, thousands of times over.

However, despite being encoded and microscopically small, we biologists have already found a way to read the DNA molecules, and we are already getting very valuable information from it. In our DNA, we can read the difference between a blue-eyed and a brown-eyed person, or we can predict if someone will be prone to suffer heart attacks from what we see in their DNA.

But we need to extract the DNA before we can read (sequence) it. That means that literally we need to open the cell to reach the DNA. Our cells, and those of all animals in general, use a membrane made of lipids (i.e. fats) to shape them and contain what’s inside, and this membrane is easy to dissolve, or in a more technical word, to lyse (from the Greek lýsis, solution). It works very much in the same way we wash our hands and clean the dishes: we use special kinds of soap, called detergents, to remove this fatty cell cover.

Other organisms (and even some animal cells) have additional, tougher cell covers beyond the lipid membrane to keep the cell safer. For instance, plant cells have such harder-to-break walls that soapy reagents are not useful against them. Still we can succeed extracting enough amounts of DNA for analysis: since plants are multicellular organisms, we can use harsher (but less effective) reagents and it doesn’t really matter if we break all or just a portion of the cells in the sample. We can still extract enough material to work with.

But what if we only had one cell available? Many, many living creatures consist only of one cell, and they are the kind I’m interested in. We don’t see them, but they are everywhere: in lakes, rivers, oceans, soils, plant roots, inside animal guts… They are so diverse, and yet we know very little about them. Maybe because they pose several challenges: a major one is that many unicellular organisms have even stronger walls than plants to protect themselves, and in such cases the many-cells approach is either worthless or impossible.

Sometimes worthless because, unlike multicellular beings, each organism is now a single cell, so if we collect many cells of the same species we would have as many organisms, and we wouldn’t be able to tell the difference between them. We would still get information about the species as a whole, but not about each individual. It would be very useful, for example, to discriminate between harmless individuals and other carrying DNA variants that make them harmful. Taking advantage of their genetic difference we could decrease the harmful without affecting the harmless, preserving biodiversity.

It is often impossible because we are not able to collect many cells of an interesting species only. We just can collect them alongside many others. If we would sequence that, we would have a mess of DNA very hard to disentangle. And usually they can’t even be cultured in the lab. Since there is no way to get many identical cells, we have to deal with single isolated individuals.

We need information about individual cells to understand their vast diversity, and therefore we have to isolate their DNA for sequencing. However, first we need a chemical hammer to open them. Something strong to crack them open but at the same time mild to preserve the DNA, and very efficient: a cocktail that lyse a cell (almost) every time we try. That’s what I’m trying to find.


About the author


I graduated in Chemistry at the University of Barcelona with a project on environmental electrochemistry, but finding it not enough engaging I decided to turn to Biology, specifically Genetics. By then, I was in charge of the microscopes at the Cryo-electron Microscopy Unit of the Scientific and Technological Centers of the UB, a time at which I enjoyed a lot learning and working with people from many different disciplines in Biology. […]