CELLS alive! Library: Contents of Volume 8

8.1 Bacteria on a Kitchen Cutting Board

Fresh chicken was placed on a cutting board and the juices allowed to stand at room temperature for three hours. The result is growth of a massive population of motile rod-shaped bacteria.

8.2 Caenorhabditis elegans (C. elegans)

This free-living nematode has been used in research since the mid-1960's and is important in the study of cell differentiation. An adult worm is about 1mm in length and feeds on bacteria. The pulsating structure seen in this video clip is the very active pharynx.

8.3 Diatoms

Diatoms are very common unicellular algae that have a characteristic cell wall of silica. They exhibit a wide variety of shapes, some quite exquisite. Many are non-motile, but the diatoms in this clip, collected in a mountain creek, exhibit a slow gliding motility.

8.4 Vorticella

Vorticella is a stalked ciliate that is usually found with its based attached to a twig, leaf, or other detritus. A ring of cilia constantly beats around its "mouth" creating a vortex, thereby drawing in food which consists of smaller unicellular organisms and bacteria. The stalk resembles an over-extended spring when the Vorticella is feeding. When the animal is disturbed, that spring (called a myoneme) contracts abruptly.

8.5 American Dog Tick- Dermacentor variabilis

This clip shows how ticks try to hitch a ride on a mammalian host. The tick climbs to the tip of a blade of grass and waves its forelegs, testing the air for the scent and warmth of a passing host. Should a host brush against the grass, the tick will immediately grab a ride. Ticks are vectors of several diseases. The dog tick can carry Rocky Mountain Spotted Fever, caused by Rickettsia rickettsii. Other species of ticks transmit Lyme Disease (Borrelia burgdorferi), Ehrlichiosis (Ehrlichia sp.), and Babesiosis (Babesia microti).

8.6 Ciliated Epithelium

Specialized epithelial cells, covered with cilia, have specific jobs in the body. As an example, cilia on the epithelium in the back of the nose beat synchronously to continuously flush out foreign particles.