Category Archives: adaptation

Amphibian skin bacteria shown to fight off Batrachochytrium dendrobatidis.

A year ago researchers at James Madison University discovered that, Pedobacter cryoconitis, a bacteria first found on the skin of red backed salamanders, was found to prevent the growth of the chytrid B. dendrobatidis, which is currently decimating frog populations.

(Mountain Yellow-Legged Frog from wikipedia)

The newest research on the subject is being presented this year at ASM by Brianna Lam who worked with other biologists from both San Francisco State University and JMU.

Lam’s research indicates that adding pedobacter to the skin of mountain yellow-legged frogs would lessen the effects of Batrachochytrium dendrobatidis (Bd), a lethal skin pathogen that is threatening remaining populations of the frogs in their native Sierra Nevada habitats.

Lam first conducted petri dish experiments that clearly showed the skin bacteria repelling the deadly fungus. She then tested pedobacter on live infected frogs, bathing some of them in a pedobacter solution. The frogs bathed in pedobacter solution lost less weight than those in a control group of infected frogs that were not inoculated.

In addition to the lab experiments, the JMU and SFSU researchers have studied the yellow-legged frogs in their natural habitats and discovered that some populations with the lethal skin disease survive while others go extinct. The populations that survived had significantly higher proportions of individuals with anti-Bd bacteria. The results strongly suggest that a threshold frequency of individuals need to have anti-Bd bacteria to allow a population to persist with Bd. (from Eureka alert)

The research above is really interesting and I am curious as to how the bacteria is actually killing the chytrid. The only other research I can think of where chytrids were being killed was a BBC news article that wrote about scientists bathing frogs in chloramphenicol.

Invasion of not so tasty truffles.

(Truffle picture from BBC.com)

The BBC (link) has an interesting article about a  Chinese Black truffle being found as an invasive species in Italy. The Italian’s and European truffle aficionados are worried that the Chinese Black Truffle will outcompete the Perigord Black truffle, which is supposed to be very tasty and the second most expensive truffle by weight, behind only the Piedmont White Truffle.

The scientific journal article (link) the BBC cites is present in the new phytologist and was authored by a lab from the “Dipartimento di Biologia Vegetale dell’Università di Torino. Looks like the Chinese truffle species could be a good invasive species model and also economically important.

Truffles are interesting its amazing people would pay so much for a mushroom, sadly I can’t say if one tastes better than the other since I have not had the chance to try of the truffles mentioned above.

Neurospora speciation through experimental evolution

ResearchBlogging.orgDettman, Anderson, and Kohn recently published a paper in BMC Evolutionary Biology on reproductive experimental evolution in two Neurospora crassa populations evolved under different selective conditions. This is a great study that complements work published last year in Nature on experimental evolution in Saccharomyces cerevisiae populations. Neurospora populations were evolved under high salt and low temperature and were started from either high diversity (interspecific crosses, N. crassa vs N. intermedia) or low diversity (intraspecific cross, two N. crassa isolates D143 (Louisiana, USA)and D69 (Ivory Coast)) as described in Figure 1. The experimentally evolved populations were then tested for asexual and sexual fitness (they were taken through complete meiotic cycle throughout the experiment to avoid insure there was selection on the sexual reproduction pathway.

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Fungus could cause a food shortage

A while back, Jason blogged briefly on a New Scientists article about the rise of a new Puccinia graminis strain, Ug99, that is spreading through West African wheat fields at an enormous rates. It looks like this story is growing in the scientific conciousness, as Science is now running an article on the spread of this wheat pandemic.

The article has a nice bit of background regarding the rise of the disease. It seems that it is spreading so quickly for due to its relatively broad host range compared to other strains. While scientists have been working to derive resistant wheat varieties, Puccinia has successfully foiled their recent attempts by mutating to acheive resistance to the plant expressed Sr24.

To boot, this strain has been found in Yemen, allowing its spores to hitch a ride along the winds that blow north along the Indian Ocean, putting much of the global bread basket at risk (I imagine that the last thing the middle east needs right now is a wheat shortage). The last time a rust spread through this area, it caused 1 billion dollars in damage. Given the extensive host range of this variety, experts predict that damages will exceede at least three times this amount.

The spread of the rust pandemic

Fortunately, researchers in Ethiopian have derived two wheat strains that may be resistant to Ug99. However, it can take several years to get these wheat strains in the ground and, ultimately, no one is certain that Ug99 won’t cleverly find a way to adapt resistance. We should keep our ears to the rail on this one: it could be a big problem.

Experimental cooperative evolution

Blogging about Peer-Reviewed ResearchA paper in Nature this week describes how a few mutations can alter the interactions between species in a biofilm from competitive to cooperative system. This is a great study that goes from start to finish on studying community interactions, looking at an evolved phenotype, and understanding the genetic and physiological basis for the adaptation.

Acinetobacter sp. and Pseudomonas putida were raised in a carbon-limited environment with only benzyl alcohol as the carbon source. Acinetobacter can processes the benzyl alcohol, while P. putida is unable to. Acinetobacter takes up the bezyl alcohol and secretes benzoate that P. putida can then use as a carbon source. The research group propagated these in chemostats and looked at different starting concentrations of the organisms. They found that evolved P. putida had a different morphology and did several experiments to determine the relative fitness of the derived and ancestral genotype.

They went on to also map the mutations in P. putida and found two independent mutations in wapH (I think this is the right gene)—a gene involved in lipopolysaccharide (LPS) biosynthesis. They then engineered the ancestral strain to have a mutation in P. putida and found the rough colony phenotype morphology indistinguishable from the strain derived from experimental evolution.

There are various evolutionary and niche adaptation implications arising from this study. One application to mycology is to how lichens evolved in that an algael cell and a fungal cell must communicate and cooperate.

Tripartate symbioses with fungi

Ants, fungi, and bacteria

I have to admit that I am fascinated by co-evolution of symbiotic and mutalistic systems. A review by Richard Robinson gives an overview. A great example is the mutalism between ants and fungi where the ants cultivate the fungi for food. There are more layers to the relationship as a fungal parasite (Escovopsis) attacks the cultivated fungi, and a bacteria. Several researchers have studied the coevolution of these studies including Ulrich Mueller and Cameron Currie. Currie and Mueller have published several great studies describing the patterns of coevolution and the nature of the cooperation.
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