Wednesday, September 30, 2009

Anatomy class: Connective tissue and bones of the skull

Last night in anatomy lab, we reviewed connective tissue, including bones in general, and specifically, the bones of the skull. We were able to get a real skull, rather than a plastic replica, but the real ones are so fragile that some of the more delicate bones (like the sphenoid) have been broken out. Still, it's a good review for the upcoming quiz; you just cannot study anatomy in 2D in the same way.

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Monday, September 28, 2009

Isolating bacteria through streak plate technique

My streak plate technique is off to a fairly good start, it seems. The streak plate method is a way of isolating bacteria into manageable colonies through a series of dilutions.

If you orient the Petri dish as a clock face, notice how thick the bacterial streaks are around the 6 o'clock position. That's zone 1, where I dipped a sterile loop into the broth containing Serratia marcescens, a pink- or red-colored bacterium often found in showers, feeding off phosphorus or lipids in soaps and shampoos. Zone 1 in my Petri dish is the growth that resulted directly from the broth.

Zone 2, which is the area at an angle to Zone 1, running from about 5 o'clock to about 3 o'clock, is less overgrown, though still pretty thick. This is due to taking the loop out of Zone 1, flaming it till it's sterile, then streaking out from Zone 1. So the bacteria in Zone 1 are correspondingly diluted over a larger area.

Zone 3, at an angle from Zone 2 from about 3 o'clock to about 12 o'clock is made in a similar way--flame the loop until sterile, and then dilute Zone 2 over a larger space. Finally, Zone 4--the lines coming out orthogonally from Zone 3--were made the same way, and usually by this point, the inoculum (sample) is diluted enough to where the bacteria can grow in individual colonies, rather than an overgrown "lawn" like in Zone 1.

My Zone 4's not perfect; I will continue to work on a lighter touch. But for an initial attempt, I'm pretty pleased with my colonies from it.


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This picture needs a title

The only one I have so far is:

* After months of catcalls from the others, Marvin and Andy finally do "get a room".

I showed this to Krystal, who expressed the hope that the shelf doesn't break under ~45 pounds of boycat.

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Thursday, September 24, 2009

Unknown rods, methylene blue simple stain

I didn't stain this particular slide tonight, but I did point and shoot. Unknown rods with methylene blue staining to make them visible; not enough information to identify them.

UPDATE: Got the title wrong last night; it's methylene blue, not methyl blue. Two different dyes.

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Wednesday, September 23, 2009

My first negative stain

Klebsiella pneumoniae, a Gram-negative rod, implicated in pneumonia and urinary tract infections. Stained 23 September 2009, Bellevue College.

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