Archives for category: Mycology

Optional subtitles: Why should I care? Do I really want to know? Thanks a lot Debbie Downer.

Consumers are becoming increasingly aware of and passionate about food quality and safety.  Not a day goes by that you don’t hear buzz words like “organic”, “GMO”, “hormone-free”, “free range”, etc.  Here in the United States, we have a (relatively) safe and secure supply of food.  However, when that security is compromised, it can be big news:

GMO wheat found in Oregon (2013)

Salmonella (2012) and Listeria (2011) found on cantaloupe

E. coli on salad greens in California (2006)

Over the next few weeks I’d like to talk about another threat that can also sicken humans and animals but doesn’t often receive a lot of press: Mycotoxins.  Mycotoxins are pervasive and fascinating, in my opinion.  However, I did spend much of PhD and post doc studying them…

What is a mycotoxin? “Myco” means fungus and a toxin is a poison; mycotoxins are small compounds produced by some fungi that are harmful to humans and animals in small doses. Symptoms of mycotoxin poisoning in humans and animals are known as mycotoxicoses. Mycotoxins associated with “poisonous mushrooms” are easy enough to avoid (don’t eat them!).  However, mycotoxins are frequently found contaminating food and feed products and are consumed unknowingly.

mycotoxin_katelynwillyerd_wheat

Many species of fungi that produce mycotoxins are also plant pathogens.  As part of their infection and colonization of the plant, they produce these toxins which end up in parts of the plant humans and animals eat. I’ll be profiling specific mycotoxins in the weeks ahead, but (spoiler alert!) some of the crops frequently contaminated with mycotoxins are wheat, corn and peanuts.

Interestingly, we don’t know why fungi produce these toxins.  Hypotheses include antiherbivory (protect a host plant and fungus from being eaten), defense against competitors (a weapon against other fungi or microbes), promotes virulence/aids in causing disease or performs some unknown function in fungal cells.

Stay tuned for more in the Mycotoxin Series.

PS – Fungi are really cool organisms and produce many compounds that have been beneficial for humans, such as dyes, penicillin, statins (for high cholesterol), etc!

Happy Friday!  Here are the stories I’ve been reading this week…

1. Amphibian plague

The fungus Batrachochytrium dendrobatidis (Bd, the chytrid fungus) is the causal agent of chytridiomycosis, a fatal disease of frogs.  In the May 2013 issue of EcoHealth, Grower et al. report that Bd can also infect and kill a limb-less, snake-like group of amphibians called caecilians in the wild.  Unless you’re an avid caecilian enthusiast (they’re out there), you may be wondering ‘so what’.  Adding more species to the Bd-susceptible list is notable because some researchers are hypothesizing that this fungus may cause disease in ALL amphibians.  Imagine a pathogen with the ability to infect all mammals.  The chytrid fungus has already been blamed for the extinction of nearly 300 amphibian species.  Furthermore, knowing Bd infects the soil-dwelling caecilian suggests that the pathogen is adept in soil survival.  It was previously known that Bd survives and is spread via water, thanks to its swimming zoospore.

caecilian, Natural History Museum via scientificamerican.com(Image: Natural History Museum via scientificamerican.com)

2. Cal State leaning toward virtual labs?

Officials at the California State University system are trying to solve the problem of “bottleneck courses”; those that difficult for students to get into, thus slowing their advancement or even causing them to drop out.  Some of these identified courses are required lab-based science courses for non-majors.  One solution may be to enroll students in virtual lab classes, involving simulations of experiments.  On one hand, this alleviates the bottleneck issue while still providing students with exposure to basic theories, problem-solving, scientific method, etc.  However, as Cal State professor Jeffery Bell cautions, the virtual lab may be too abstract for some students and give them a false appreciation of what scientists really do.  I have to agree and I’d hate to see lab sections for non-majors completely eliminated in favor of simulations.  There’s a “cool” factor to science (preparing a specimen and observing it under a real microscope, for example), that doesn’t quite translate to viewing something on a computer.

3. The Case of the Irish Potato Famine

I’m planning to write more about the Irish Potato Famine next week since it’s one of the great historical plant pathology stories (yes, we have those).  While the causes of the Irish Potato Famine are political as well as biological, it was announced this week that the particular strain of Phytophthora infestans, the pathogen responsible for destroying millions of potatoes in 1840’s Ireland, has been genetically identified.  This strain, known as HERB-1, was responsible not only for the deaths of an estimated 1 million people but also immigration of many Irish to the United States and other parts of Europe.  More next week…