[Script Info]
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Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:00.00,0:00:05.00,Default,,0000,0000,0000,,(English captions by Andrea Matsumoto, University of Michigan.) This program will illustrate how the gram\Nstain procedure is able to distinguish gram-positive
Dialogue: 0,0:00:05.00,0:00:09.00,Default,,0000,0000,0000,,and gram-negative bacteria by representing\Nthe staining events at the ultra-structural level.
Dialogue: 0,0:00:10.00,0:00:15.00,Default,,0000,0000,0000,,This particular animation is one of two in\Nthis series showing the staining of gram-positive
Dialogue: 0,0:00:15.00,0:00:21.00,Default,,0000,0000,0000,,bacteria with critical structures of the bacterial\Nsurface represented schematically.
Dialogue: 0,0:00:21.00,0:00:25.00,Default,,0000,0000,0000,,The circle at the lower right tracks how the\Nbacteria would appear in the microscope if
Dialogue: 0,0:00:25.00,0:00:29.00,Default,,0000,0000,0000,,they were examined during each step of the\Nstaining procedure.
Dialogue: 0,0:00:29.00,0:00:35.00,Default,,0000,0000,0000,,Prior to staining, the bacteria would be transparent\Nand invisible in the microscope.
Dialogue: 0,0:00:35.00,0:00:39.00,Default,,0000,0000,0000,,After heat fixing the slide, it is first flooded\Nwith crystal violet for one minute and then
Dialogue: 0,0:00:39.00,0:00:41.00,Default,,0000,0000,0000,,washed.
Dialogue: 0,0:00:41.00,0:00:45.00,Default,,0000,0000,0000,,The stain colors the bacterial cell wall blue\Nand the bacteria would appear blue in the
Dialogue: 0,0:00:45.00,0:00:49.00,Default,,0000,0000,0000,,microscope if examined at this point in the\Nprocedure.
Dialogue: 0,0:00:49.00,0:00:55.00,Default,,0000,0000,0000,,Next the slide is flooded with iodine solution\Nfor one minute and then washed again.
Dialogue: 0,0:00:55.00,0:00:59.00,Default,,0000,0000,0000,,During this step the iodine and crystal violet\Ncombine to form a large complex within the
Dialogue: 0,0:00:59.00,0:01:01.00,Default,,0000,0000,0000,,layers of the cell wall.
Dialogue: 0,0:01:01.00,0:01:06.00,Default,,0000,0000,0000,,Microscopically the bacteria would appear\Ndark blue or black after this step.
Dialogue: 0,0:01:06.00,0:01:11.00,Default,,0000,0000,0000,,The slide is now rinsed with a decolorizing\Nagent, an acetone alcohol solution.
Dialogue: 0,0:01:11.00,0:01:15.00,Default,,0000,0000,0000,,However, the crystal violet iodine complexes\Nare not washed out of the thick and tortuous
Dialogue: 0,0:01:15.00,0:01:21.00,Default,,0000,0000,0000,,layers of the gram-positive cell wall and\Nthe organisms remain dark blue in color.
Dialogue: 0,0:01:21.00,0:01:26.00,Default,,0000,0000,0000,,Finally the slide is counter-stained with\Nneutral red or safranin for one minute and
Dialogue: 0,0:01:26.00,0:01:27.00,Default,,0000,0000,0000,,then washed again.
Dialogue: 0,0:01:27.00,0:01:33.00,Default,,0000,0000,0000,,The red stain also confers color to the bacteria\Nhowever the red color is not apparent because
Dialogue: 0,0:01:33.00,0:01:38.00,Default,,0000,0000,0000,,of the persistent dark blue stain that dominates\Nthe microscopic appearance of the bacteria.
Dialogue: 0,0:01:38.00,0:01:44.00,Default,,0000,0000,0000,,So, by virtue of the complex multilayer structure\Nof the gram-positive cell wall, these bacteria
Dialogue: 0,0:01:44.00,0:01:48.00,Default,,0000,0000,0000,,appear dark blue or black in the microscope\Nafter this staining.