Blepharisma

From Wikipedia, the free encyclopedia

Blepharisma
Scientific classification
Domain: Eukaryota (unranked) Alveolata Phylum: Ciliophora Class: Heterotrichea Order: Heterotrichida Family: Blepharismidae Genus: Blepharisma

Blepharisma is a genus of heterotrich ciliates (a type of protista) which contains many species. Its members are elongated and roughly egg-shaped, with a contractile vacuole without collecting channels. Typically, they are pigmented with some shade of red or pink. The anterior pole is jpointed, the posterior pole is blunted. The body is noncontractile, and even within the same culture. Blepharisma reproduce by going through the 4 phases of Binary fission Blepharisma are covered in tiny hairlike parts called cilia, which allow them to move through water. They move more slowly through water with their cilia than vinegar eels.

However, compared with Volvox, they move rather quickly.They are a rosy pink color and feed on bacteria.

Blepharisma's size can range from 150 to 300 micrometers.

Blepharismas are protists that are commonly viewed under microscopes in science classes. They are readily available from scientific supply stores. Blepharisma is a microphagus filter feeder and a ciliate, it is classified in the phylum Ciliophora. Ciliates are generally considered the most evolved and complex of the protozoans. They are single celled organisms with organelles that are used for movement and food gathering.(1) Cilia are short hairlike organelles used for motion, as well as to sweep food into its buccal cavity (mouth). Blepharismas generally eat bacteria from decomposing vegetation, which is drawn into the buccal cavity and then passes to the food vacuoles at the posterior end of the cell. (2)

Blepharismas are particularly notable because of their unusual color. Unlike most protists, they are a faint shade of pink. This is not visible under brightfield illumination, so these images were shot using darkfield illumination set up on a Nikon microscope. The objective magnifications used were 10x and 20x.

Despite many still images available about their structure, there is not as much information easily accessible on the Blepharisma's behavior and movement. Still images can provide excellent views of their internal organelles, but video footage is necessary to view their movement. As with any small, transparent, moving organism there are challenges involved in video recording.

The specimens were placed onto a slide for microscope viewing, and a ring of petroleum jelly was used to seal in the water and give the Blepharismas room to move. This provided a water tight seal that kept the protists alive for over a week after the slide was prepared. If kept at room temperature the Blepharismas move very quickly making it difficult to keep them in view by moving the microscope stage. After being placed into a refrigerator for several hours, they slow down notably making them easier to follow. Various substances such as glycerin can be used to suspend or greatly deter motion, however chilling the specimen was sufficient for viewing their normal movement.

A Nikon microscope was used, with a darkfield condensor to illuminate the ciliates. A peanut microscope camera was placed where the photo reticle would ordinarily be, and it was hooked up to its control unit. An S-video cable out of the control unit was hooked up to a Canon GL-1 digital video camera for recording.

As you can see, because of its cilia on all sides, the blepharisma can turn in any direction and often spins around. It spirals as well as spins in a circular motion. It can change direction very easily, which makes it somewhat difficult to keep in view on a microscope. Also, because it is suspended in a 3-dimensional water bath, it moves up and down in and out of the focus of the microscope. I obtained the best results by using a maximum of the 10x and 20x objectives, and by persevering in capturing enough footage that it could be edited to include only segments that were in good focus. I used Adobe Premiere for the video editing, and exported it as a QuickTime file, compressed for web viewing.

Some ciliates reproduce by fission, and some reproduce by conjugation - including Blepharismas. Conjugation is an exchange of genetic information to reproduce that occurs when two organisms of the same species fuse for a period of time.(3) They exchange nuclear products that results in the reshuffling of hereditary characteristics, as in sexual reproduction. Conjugation does not always result in immediate increase in numbers, often it is immediately followed by binary fission.(1)

As you can see the pair of ciliates is less agile than the individuals. They still spin, and in general they move together, but at times they appear to conflict or to attempt to pull in different directions. There is a slower rotation with the pair, but they do move up and down in and out of the focus of the microscope. Finding conjugating pairs is more difficult than finding individuals. When the slides were initially prepared all of the specimens on them were individuals. The slides were then left to sit for several days, at which point there were multiple sets of conjugating pairs present.