Submitted by Alexander GettyIn a previous lab, we inoculated petri dishes with Ceratopteris richardii (known as “C-fern”) spores. The C-fern is a species of aquatic fern native to the tropics, and is a popular “model organism” for lab use because it is easily cultured and has a fast life cycle. It is our goal today to find and follow one of the C-fern sperm cells on its journey. It will not be easy; these tiny, multi-flagellate cells are on a mission, moving very rapidly. They do not have much time, maybe 48 hours max to reach their target destination, before the solitary cell consumes all its resources and will die. Will the sperm make it? Will it fulfill its duty, and succeed in its sole purpose of existence? Ferns reproduce by first producing a spore by meiosis. These spores are dispersed, and generate the gametophyte body. The gametophytes of the C-fern may be either male, which are smaller, or hermaphrodite, which are 4-5 times larger and “mitten” shaped. Male gametophytes develop structures called antheridia which produce and disperse sperm cells. Hermaphrodites also have antheridia, but produce and disperse sperm less effectively. Instead, hermaphrodite gametophytes have a second structure called the archegonium, where the egg develops. In contact with water, male antheridia release their flagellate, swimming sperm on an epic journey to locate and penetrate the archegonia of the hermaphrodite C-fern gametophytes. If successful, this will fertilize the egg, and develop into the embryo of a new sporophyte body, which will then produce more spores and start the cycle again. Using a dissecting microscope, we examined our petri dishes and locate a few male and hermaphrodite C-fern gametophyte bodies. We will then transfer these to a slide with a drop of water for viewing under the compound microscope. The water should cause the male antheridia to release their sperm cells on their journey. The sperm of the C-fern is no easy prey, as I quickly find while trying to capture one on film. Not only are they tiny and quite quick, but they are also more or less translucent. For quite some time you will notice as I attempt to catch one of the sperm being released from the antheridia, with no luck. Some sperm is visible stuck between the gametophyte body and the cover slip, spinning in place, and then at the 3 minute mark we see one sperm break away and set off on a fantastic journey. Spinning around wildly, the sperm swims to and fro while I frantically try to keep it in view and in focus, only to eventually exhaust itself and stop. Ceratopteris richardii “C-fern” gametophyte at 400x magnification, showing first the male body with its antheridia, then eventually a free swimming sperm. Courtesy of Alexander Getty
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Amateur Botanist Explores Microscopic Magic Crystals, Extra-Hairy Plants, and Alien Spores1/15/2017 I am a house plant addict. As in, turn-my-apartment-into-a-jungle-and-call-it-home kind of addict. I could use the phrase ‘house plant enthusiast’, but it doesn’t quite capture the depth of my affection for these organisms. So imagine my excitement upon seeing a table full of some of my favorites placed at the front of the lab room. Imagine again my slight adrenaline rush in in learning that we were going to study them under microscopes - exploring their cells, traveling to far off places unreachable by the naked eye. I was stoked. For starters, I had a quick *heart eyes* moment with one of the specimens, a majestic (and I do mean majestic) Begonia before diving in to the task at hand: trichome collection and examination. Trichomes are hair-like structures that cover the leaves and stem of the plant; they come in many shapes and sizes and serve a variety of functions. In some plants, trichomes are coated in sticky substances capable of trapping insects, preparing them for chemical digestion. In others, the hairs prevent herbivory by means of painful chemical injection. Begonias are more ‘sunshine and daisies’ when it comes to their epidermal hairs, most likely serving to collect moisture from the air or prevent herbivory by having an unpleasing texture. After producing a wet mount slide, I was surprised to see a difference in the cellular shape of the trichome relative to the those of the leaf it was attached to. Where leaf cells were circular in shape, cells of the trichomes were rectangular. Furthermore, fuzzy deep red pigments were mixed with slight pockets of green – an act of Christmas regurgitating its holiday sprinkles all over this plant or anthocyanins masking chlorophyll pigments? I’ll let you decide. Next up: examining raphide crystals found within Tradescantia zebrina (aka “Inchplant”) and druse crystals formed in an unknown species of Begonia via wet mount slides. These structures are products of excess inorganic particles (most often calcium salts) being deposited into the vacuole in crystalline form. The raphide crystals were easy enough to find, often found in clusters mixed with cell matter. However, searching for druse crystals felt like searching for Waldo in a sea of cartoon people; you find him once, painstakingly, and then you can’t find him again. My favorite part of this lab reminded me of one of my all-time favorite films, The Fifth Element, which revolves around the “untraditional hero saves planet” trope. Bruce Willis plays Korben Dallas, an ex-galactic special forces operative turned cab driver of the 23rd century, who attempts to save the world from a giant ball of talking fire in space. I can't make this stuff up, guys - its cinematic gold. That giant ball of talking fire, who calls himself "Mr. Shadow", looked pretty similar to the Ceratopteris richardii spore under my microscope (in my humble opinion). Under 400x magnification, the surface ridges on this tiny sphere give it the look of some far off planet in outer space. In reality, it comes from an aquatic fern found on Planet Earth, dubbed the “C-Fern”. Our mission: examine the spores under a microscope and sow into prepared culture plates containing agar and mineral nutrients, where it will be examined further in the coming weeks. Author: Amy KHouse plant addict. Believer in Himalayan Salt lamps. Enjoys the little things in life like popcorn and vegan marshmallows. |
AuthorContent is created by students participating in the Plant Structure course at Oregon State University for Winter 2017. Archives
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