CONvergence on the Brain

So, I spent this past weekend at CONvergence/SkepchiCON so my brain isn't quite recovered. However, I am not willing to let you go without anything, so I give you some David Attenborough.

Fungi- The Private Life of Plants excerpt

Fungal Word Friday

Conidia

Asexual spores supported on a hypha, as opposed to being contained in a sporangium.

A chain of conidia

Photo via Wikimedia.org

Come Together, Right Now.

Speckled leaf blotch is a detrimental crop disease in many parts of Europe and the Middle East. It is a fungal infection that can cut wheat crops in half. While doing genome alignment of a close relative, which infects mainly Iranian grasses instead of wheat, of the the blotch causing Zymoseptoria tritici, a group of scientist have uncovered a quite recent case of natural hybridization. Like just in the past few centuries type of recent.

 Fusion of two divergent fungal individuals led to the recent emergence of a unique widespread pathogen species (Abstract only)

Hybridization occurs when two different species manage to interbreed. While this generally leads to infertile, week and normally short-lived offspring in animals, it is a regular evolutionary happening in plants and fungi.

Isolates of Zymoseptoria pseudotritici

In this case, the scientists looked at variations of Zymoseptoria pseudotritici and found what they called "peculiar diversity patterns." They found that segments of the genome from regional samplings would go for large regions of matching base pairs, intermittent with equally long regions of variation.
This type of genome pattern is in line with a hybrid speciation event, and with further analysis of the variations the team concluded that Z. pseudotritici arose approximately 380 sexual generations.

This kind of study goes to show that hybridization of potentially dangerous(especially in agribusiness) fungi can happen very quickly on a evolutionary time scale. We have to make sure that in a global society, where potentially infested plants can be traded worldwide, we take into account the fact that such hybrids could quickly arise and devastate crop supplies.

For more on this study i give you the coverage from Science Daily: Two Species Fused to Give Rise to Plant Pest a Few Hundred Years Ago


Photo credit: Janine Haueisen

Happy Fungus of July!

In tribute to Fourth of July I present to you red, white and blue in mushroom.


Witch's Hat (Hygrocybe Conica)

Slimy Beech Tuft (Oudemansiella mucida)

Steel Blue Entoloma (Entoloma hochstetteri)

Photo credits: Daniel Schwen, Walter Baxter, Ian Dodd

Bats that Roost Together Get White Nose Syndrome and Die Together

White Nose syndrome is a newly introduced disease caused by the fungus Geomyces destructans, which appears to have recently been introduced into North America from Europe and was first diagnosed in 2006. The disease gets its name due to the white fungal growth on the muzzle and wings seen on hibernating bats.

Little Brown Bat infected with Geomyces destructans

Once infected, the bats routinely rouse during typical times of torpor when they normally are conserving energy. This unfortunately ends with the bats going through excessive weight loss and eventual starvation in winter months, when they cannot find food to sustain this activity. The mortality rate in some colonies is as high as 95%.

Now, a study published in the July 2, 2012 edition of Ecology Letters has linked the social interactions of various bat populations to rates of infection from G. destructans.

Sociality, density-dependence and microclimates determine the persistence of populations suffering from a noval fungal disease, white-nosed syndrome

The authors of the articles examined colony sizes of 120 different populations across 6 different species of bat in the northeastern United States. They did this by utilizing colony counts issued by trained biologists in state natural resource agencies during the typical months of Hibernacula over various years from 1979 to 2010.  This allowed for population growth measurements both before and after the fungus was introduced into the population.

The team found that infection rates of WNS was not based solely on population size, but more closely related to population roosting density and socialization rates of the bats. This information can then be used to extrapolate which species are at the most risk of severe population decline and potential extinction.

All sample populations decreased in growth after WNS infection and 32 of the 120 groups actually became locally extinct. Bats that routinely roost solitarily, such as the tricoloured bats, were noted to only have severe infections during times when the bats were drawn into larger groups such as overwinter roosting. This lead the teams to conclude that while they would be a loss of population size, the overall population could stabilize once the animal population density became low enough to allow for more the bats to roost more spaced out from one another. Bats such as the little brown bat however are known to roost regularly in large close knitted colonies. These bats are not likely to stabilize in decline once hitting a lower population size, and instead continue the spiral until extinction.

With this study we can determine which species of bat populations are at the most risk of extinction once infected with g. destructans, and with that knowledge we can adjust our tactics of fighting a powerful pathogen to those groups that are in the direst situations.

Photo credit: Alan Hicks, NY Department of Environmental Conservation

Finding Fungal Infections Fast

Fungal infections are rough. Once they have infected a host, they are difficult to fully cure. Because of that tenacity it is very important to identify not only that one has a fungus, but what kind of fungus it is, quickly.

Unfortunately there are a lot of problems with the diagnostics implemented in today’s medicine.  Cultures of fungi can take a long time to bring results, and even then they can be false negatives.  Diagnosing from nucleic-acid amplification can detect a fungus, but with that there are several step techniques that must be done after the amplification to present any kind of difference in some of the major fungi. If you are rich you can always go for the DNA sequencing, but that is not something that can feasibly be done for every infection. So with all of these time consuming, expensive and/or inaccurate techniques we find ourselves without an ideal set of diagnostics tools.

But we got people on that.

A new study published July 2, 2012 in PLoS One has demonstrated a new PCR Method (Polymerase-Chain Reaction High-Resolution Melting) that shows promise at not only detecting both yeasts and filamentous fungi, but also differentiating between them, as well as between some of the more relevant yeast species.

New Strategy for Rapid Diagnosis and Characterization of Fungal Infections: The Example of Corneal Scraping

According to the teams journal article, over the past thirty years there has been a large uptake in reported fungi infections. Yeasts have been more responsible for serious disease but with filamentous fungi showing up in conditions such as Keratitis.

Fungal Keratitis

Keratitis is a condition in which the cornea becomes inflamed. A study in the March 2000 issue of Ophthalmology found 88 cases of fungal keratitis at the L.V. Prasad Eye Institute in India.

Keratomycosis: clinical and microbiologic experience with dematiaceous fungi.

With this increase, as well as the different therapies that are needed for treatment,  the team felt it was important to find a less labor intensive and cheaper method than DNA sequencing of quickly identifying what fungus is causing an infection.

To accomplish this, the team took a variety of samples from isolated strains as well as, suspected infections, and suspected bacterial/viral infections. They took these samples and extracted DNA, then mixed them with specific primers diluted in MeltDoctor® HRM Master Mix (CandUn, and FungUn for yeast, and FilamUn and FungUn for filamentous suspects).  They then monitored the yields of DNA extracted and what PCR inhibitors arose.

With their method the team managed to detect and differentiate between 0.1 colony forming units/µl. The new technique even detected and characterized fungi in 7 out of 10 suspect cultures that appeared negative.

It is always good to hear of new methods being developed that show promise of helping quickly and accurately diagnosing disease agents. The faster we find our culprit, the faster we can find ways to effectively fight it.

Mycena mushroom drawing.

Nothing important today, just a drawing I did of some mushrooms from the Mycena genus.