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Giant Genes for Tiny Organisms

How big can a gene be? Ten years ago in the early days of genome sequencing, researchers scoured the genomes of 580 bacterial and archaeal species for large genes. They found that 0.2% of all genes identified are longer than 5,000 bases and 80 of them are “giant genes,” those larger than 15,000 bases. To put this in perspective, the average prokaryotic gene length is between 900 and 1,200 bases.

The two longest genes were found in the green sulfur bacterium Chlorobium chlorochromatii CaD3. The genes encode proteins 36,806 and 20,647 amino acids long and their corresponding genes would be 110,418 and 61,941 bases long, respectively. At the time of this research, these giant genes are only surpassed in length by the human titin coding sequence which is 38,138 amino acids long. Now, scientists have identified a slew of genes that exceed one million bases long. (more…)

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There’s a Fungus Among Us and It's Making Peppers Spicy

Though the heat of the chili pepper has taken our culinary adventures to great heights, the spiciness of chili peppers was not designed to attract hungry diners. Spiciness actually evolved to defend the plant against fungal predators.

Peppers, like many fruits, are colorful, sweet, and appetizing, designed to attract animals that help bring seeds to new ground. But along with inviting animals beneficial to the plant’s survival, fruits also lure consumers that destroy seeds. Thus, fruit chemistry hangs in a delicate balance. The chemicals produced by the fruit must keep predators at bay, but must also not negatively affect seed dispersers. (more…)

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Happy Birthday Robert Koch!

On this date in 1843, Robert Koch, the founder of modern microbiology was born.  And on December 10, 1905, one day before his 62nd birthday, he was awarded the Nobel Prize in Physiology or Medicine for his work on tuberculosis.

But what many microbiologists are more familiar with are the Koch’s postulates, four criteria needed to establish a causal relationship between microbe and disease. These are:

  • The microorganism must be found in individuals suffering from the disease, but in not healthy individuals,
  • The microorganism must be isolated from a diseased individual and grown in pure culture,
  • The cultured microbe should cause disease when introduced into a healthy individual, and
  • The microbe must be isolated from the inoculated individual and identified as the same microbe from the original source.

Now, more than a century after Koch’s time, how do these postulates hold up? (more…)

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Meet a Microbiologist: Marcos Voutsinos

While most of us worry about the ripeness of our bananas, Marcos Voutsinos has been preoccupied with something else: the banana freckle. Despite its innocuous name, banana freckle is actually a fungal disease caused by the fungus Phyllosticta cavendishii and characterized by “freckles” of fungus on the banana fruit, leaves, and stems. The fruiting bodies of P. cavendishii can spread up to 1 km during the tropical monsoonal weather making this microorganism a serious concern for the $600 million Australian banana industry. (more…)