I got sent a wonderful story recently about a group of ten college students, from St Olaf college in Minnesota, who went on an electron microscopy course at the Boulder Laboratory for 3-D Electron Microscopy of the Cell in Colorado. As well as being shown the techniques and equipment in use, the students actually got a chance to use the microscope, and what they produced is spectacular.
The video above is a 3D model of a tomogram of a single cell of the freshwater protozoan Tetrahymena thermophila that the students produced. The strange otherworldly blobs and crevices are internal cellular membranes, while the red rods are cytoskeletal fibres. The whole video builds up the internal world of the cell as an undeniably busy place, full of membranes and vacuoles and separate compartments.
To produce this video, the students took thin slices from the cell and photographed them using the electron microscope. A computer program was then used to put these slices together into a full 3D image of the cell. A colour model was then rendered, with the original grey micrograph in the background for reference (you can see it in the video above). The video was then able to travel through this 3D landscape, capturing it from different angles.
Although at first glance, the two images above look very different, a closer look reveals clear similarities. The membrane around the edge of the picture on the left, and running down the middle, has been rendered in green. The dark curved blob on the right hand side is in purple on the right hand side of the model, and all other little purple blobs can be matched to their corresponding marks. However the coloured 3D version has a great advantage over the static thin black and white images – it can be explored in all dimensions and it is much easier to see the connections between membranes.
This image wasn’t just produced as an exercise either, the students were actively exploring the mating of Tetrahymena thermophila. As well as confirming earlier studies that showed pores forming between two mating cells, they also discovered that each pore was filling with a system of branching membranes. The pores expand during the mating process to allow DNA to pass between cells, which means that these membranes could be helping to guide the DNA, or protect it as it moves between the two mating organisms. EDIT: it has since been pointed out to me that as these are protozoa rather than bacteria it isn’t just ‘DNA’ that is passing through these pores, but the entire nucleus!
It’s a brilliant project for young students to get involved in, and they all had a great time taking part. There really is no better way to find out about scientific research than by actually getting out and doing some!
Thanks to St. Olaf college for permission to reproduce the video and images. Their press release can be found here.