The first story comes from the sea. There is a group of phages that specifically infect cyanobacteria, guess the name… cyanophages… which are divided into three main families: Podoviridae, Myoviridae, and Siphoviridae. Well, it’s been found that these phages carry genes that encode two photosystem II* core reaction-center proteins. By expressing their own copies during infection these phages can manage to enhance photosynthesis. Interestingly, cyanophage production is optimal when photosynthesis is maintained during infection.

I’m only guessing, but I suposse that during infection the host cell stops photosynthesizing, due to the stress conditions, and for some reason the virus needs this machinery working. Why? not a notion! Do you know anything about this, help me. By the way there’s a paper studying the evolution of this genetic exchange between bacteria and virus.

* Photosystems I and II are the two reaction centers in photosynthesis

phages

The second story is about viral trade-offs. Marianne De Paepe and François Taddei from the University of Paris have published an article about the increase in the decay rate* of coliphages when certain conditions are given. They found that this decay rate increases with the density of the packaged DNA (into the phage), so, higher internal pressure higher mortality. This also increases when surfacic mass decreases, so the bigger the better. And finally, and this is the main reason of this comment, they found the highest correlation between decay rate and multiplication rate in the bacterial host.

So, interestingly for phages, survival rate is inversely proportional to multiplication rate. The reason behind this is yet to be known but will be fascinating for sure.

* It is not very accurate to say death since they are not alive