Monday, August 5, 2013

Anna Russell- Trial and Error

I mentioned last week that we were going to inoculate the eelgrass with Labyrinthula spp. on Monday. This was to test the resistance of herbivore-damaged eelgrass to eelgrass wasting disease, caused by Labyrinthula spp. On Monday, I pipetted Labyrinthula cells onto autoclaved 2-cm pieces of eelgrass. I also pipetted sterile sea water onto autoclaved 2-cm pieces of eelgrass as negative controls. After letting them rest for three hours (to give the Labyrinthula time to infect), I used a plastic clip to attach the autoclaved, infected eelgrass to one of the healthy blades of eelgrass. This was a little tricky because I had to use sterile technique, which means I had to attach the clip with tweezers. After awhile, I got the hang of it and it went pretty fast. Then, we just had to wait for the eelgrass to get infected. I had expected to see signs of infection by the next day but when I checked the eelgrass on Tuesday, it showed no signs of infection. On Wednesday, one looked infected. On Thursday, a couple more showed black spots. By Friday, twelve plates looked infected so I took the plastic clips and autoclaved eelgrass off.

However, twelve out of seventy-two is a very low percentage. The lack of infection could be for many different reasons. When a disease like Labyrinthula is cultured in a lab, it becomes less pathogenic over time. The two strains I used have been cultured for many years so it is possible they are not very infective anymore. Another possible reason is that the Labyrinthula didn't stick to the autoclaved eelgrass so when I attached the autoclaved eelgrass to the healthy piece, there wasn't any Labyrinthula to infect the plant. The last reason is that perhaps the eelgrass is extremely healthy. It isn't stressed by dessication or tidal fluctuation. Labyrinthula is an opportunistic infection so if the eelgrass hasn't been weakened, perhaps the Labyrinthula can't infect.
An eelgrass piece that shows no sign of infection
The black spots could be Labyrinthula but it is not large enough to tell for sure
An eelgrass blade clipped to the autoclaved piece of eelgrass

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