BioQuakes

AP Biology class blog for discussing current research in Biology

Author: sgagliotide

Killer Cells Caught Red-Handed!

Antibiotics are most commonly used to treat bacterial infections, but bacteria are rapidly able to evolve and resist these drugs, contributing to superbugs. Immune killer cells or white blood cells, however, are seemingly more effective at destroying bacteria cells. How do our immune cells fight bacteria so efficiently? What exact mechanisms do killer cells use to track and destroy bacteria and can we replicate those mechanisms with drugs?

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White Blood Cell (farthest to right)

A common way immune cells can the trigger death of bacteria is by oxidizing the bacterial cells. However, immune cells are still able to destroy bacteria in environments without oxygen leading scientists to believe other methods are also used in attacking bacteria.

Scientists have recently discovered that immune cells methodically kill cells without the use of oxygen. The immune cells do this by shooting enzymes into bacteria to program the bacteria to self-destruct. Scientists have discovered this by observing immune killer cells as they destroy E. coli and the bacteria responsible for Listeria and tuberculosis. They measured the protein levels of each different bacteria before, during, and after the immune cells killed the bacteria. Each bacterial strain started with about 3000 proteins and ended up losing around 10% of their proteins due to the immune cells injected enzyme called granzyme B. Those 10% of proteins destroyed, however, were necessary to the survival of each bacteria. Granzyme B also shuts down ribosomes preventing the bacteria from making new proteins.

This discovery is significant at a time where antibiotics are becoming less efficient and superbugs are becoming prevalent.  Scientists hope to design a new drug that will treat bacterial infections in a similar way to our own immune killer cells.

Tree Lobsters Are Back!

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Lord Howe Tree Lobster

Tree Lobsters are actually not lobsters at all. Nor are they crustaceans.  They are actually just insects with a similarly shaped exoskeleton. But that’s not what makes them interesting. What does, is that Tree Lobsters have seemingly come back from extinction.

The Species, originally from the Lord Howe Island in the Tasman Sea between Australia and New Zealand, went extinct during the 1920’s due to becoming the main food source for an invasive rat species that came onto the island. The Tree Lobsters were only formally declared extinct in 1960 though. Since then scientist had pretty much forgotten about them.

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Ball’s Pyramid Stick Insect

Thus, when scientists found a small group of stick insects similar to Lord Howe Tree Lobster’s on Ball’s Pyramid, a volcanic stack 12 miles away from Lord Howe Island, in 2001, they were quite surprised. The Ball’s Pyramid stick insects were skinnier and darker but scientists were still hopeful the newly discovered insects were, in fact, the same species as the extinct Lord Howe Tree Lobsters. Scientists tested the genes of the stick bugs from Ball’s Pyramid with genes extracted from preserved Lord Howe Tree Lobsters and found out that despite some morphological variance, they are still the same species. They speculate that diet, age, and environment had caused the Ball’s Pyramid Stick Insects to look a little different. How the species got to the volcanic stack is still a mystery as the insects cannot swim but they infer that they had been carried over by birds.

The newly discovered Tree Lobsters are now being bred at the Melbourne Zoo and elsewhere in an attempt to reintroduce the species to Lord Howe Island. However, the invasive rat species on Lord Howe Island still remains a problem as it threatens the lives of over 70 different native species. In order to successfully reintroduce the Tree Lobsters back to Lord Howe, the rat problem needs to be taken care of first.

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