Cell Division: Mitosis and Cytokinesis

Instructor's Guide


These notes provide brief background material for teachers using the video. Many sequences were recorded using green light because the cells are least sensitive to strong illumination at this wavelength.

Locating specific sequences: If the timer of the VCR is zeroed at the beginning of the first sequence, the times below indicate when each sequence starts.

Time Lapsing Rate: Many sequences were recorded in real time (RT); for other sequences, either the rate of speeding up the action is indicated thus: X50, or else the duration of the sequence is given (e.g. 3 hrs.). The figures are approximate, since the recording rate was frequently altered as the action slowed or speeded up.

Other Abbreviations used:

DIC : Differential Interference Contrast optics (often termed Nomarski optics).

PC : Phase Contrast optics

NOTES

DESCRIPTION

0' 52"
An unidentified amoeba (Penardia sp. ?); DIC, 25X.
1' 00"
Amoebae of the cellular slime mold Dictyostelium; PC, 25X
1' 08"
Collection of mainly euglenoid flagellates from a stagnant pond; DIC, RT.
1' 14"
The weakly filamentous green alga Klebsormidium; DIC, 50X
1' 19"
Stomatal complexes in the epidermis of a leaf of Tradescantia; PC, 25X.
1' 26"
The green algae Volvox: this male colony has differentiated "sperm packets" which soon are released to seek out female colonies. DIC, 50X.
1' 33"
The comb jelly (ctenophore) Beroe; the coloured, flickering lights on its surface are rows of cilia.
1' 43"
The rotifer Floscularia feeding; DIC, RT.
2' 20"
The blue-ringed octopus is a small, shy creature which nevertheless can inflict fatal bites. The poison is tetrodotoxin, produced by bacteria living in its salivary glands. Cells involved in color changes, the chromatophores, are widespread, particularly in fish, and many students have probably noticed how certain fish in aquaria can change color quite rapidly.
2' 57"
(Green background to titles). Cultured mammalian PtK cells growing on a slide. PC, 1 hr.
4' 17"
These newts, Taricha, found in western U.S., have been a favoured source of cultured cells for microscopists for over 100 years.
5' 33"
Newt lung cell; DIC, 2.5 hrs.
5' 57"
The animation: The two sets of spindle fibres are entirely equivalent. We show them in different colors to make it easier to follow how they interact with each other and the chromosomes. Note that the fibres (microtubules) from the centrosomes are continually shortening and lengthening. This surprising property has turned out to be important because the fibres can probe amongst all the chromosomes.
7' 11"
Prometaphase animation. Prometaphase is very complex and poorly understood. We know that during their initial interaction, kinetochores on the chromosomes slide polewards along the fibres. However, very soon, these same fibres come to terminate directly in the kinetochores; how this happens is not clear. Once each chromosome attaches to the other pole as well, one set of attached fibres has to shorten while the other lengthens as the chromosome moves to the centre of the spindle.
7' 53"
(Green illumination). Newt lung cell. DIC, 75X
8' 37"
Newt lung cells. PC; about 4 hrs.
10' 19"
(Blue illumination). Newt lung cell. DIC, 75X.
10' 59"
Tradescantia stamen hairs. The purple hairs from older (opened) flowers are wonderful for students to watch living cytoplasm under the microscope. Mitotic cells are found in very young buds (1.5mm approx); cut off the top and bottom of the bud and gently tease out the tiny stamens surrounded by the hairs. Mount in water.
12' 11"
(Green illumination); Haemanthus endosperm, DIC; 100X
13' 10"
Background for Meiosis heading: these are spermatocytes dissected out of male crane flies.
13' 28"
(Green illumination): crane fly spermatocytes. DIC, 75-125X.
14' 20"
Unknown amoeba. DIC, 25X
14' 34"
Unknown amoeba. DIC, 75X
14' 58"
The euglenoid flagellate Phacus. DIC, RT.
15' 10"
The pellicle (skin) of Phacus consists of interlocked strips. Before division the number of strips doubles and then cleavage divides the pellicle into two equal sets of strips.
15' 28"
The green alga (desmid) Micrasterias. PC; 3 hrs.
15' 54"
The green alga Gonium. PC, RT.
16' 03"
The green alga Gonium. DIC 6 hrs.
16' 26"
The toad Xenopus. The early cleavages take some hours; tadpoles are released about 30 hrs. after fertilisation.
17' 32"
Eggs, embryos of the zebrafish Danio. The sequences here cover the first 48 hrs of development.
18' 39"
(Green illumination). Cultured PtK cells; PC, 1 hr. approx.

Further Video Material.
Cytographics offers teachers an increasing variety of tapes and laser discs which illustrate many aspects of cellular behaviour and function in living material. Click on the link to Resources in the menus on the left.

Contact Us | ©2006 Cytographics