Microscopic Life

Instructor's Guide

OBTAINING LIVING MICRO-ORGANISMS FOR LIGHT MICROSCOPY

The cells shown in this video were obtained from two sources:

(i) a few were purchased as cultures from a local biological supply company; and

(ii) most were from samples originally obtained from local sites around our laboratory which provide a great range of varied microorganisms. Teachers can easily prepare similar samples for classroom demonstrations.

Biological Supply Houses. These are a convenient and reliable source of a few well-known cell types (e.g., Paramecium, Amoebae and some algae). They also usually supply simple culture media which saves preparation time. For a modest outlay, cells will be delivered just when they are needed for class.

Local Sources of Cells. Any obvious green or brown material growing on leaves, rocks, the surface layer of mud etc. can yield interesting material for microscopical examination. Places to look include the margins of ponds, streams, roadside ditches, piers etc.

Plankton Samples. Water samples from lakes, rivers or the ocean must be concentrated before examination because phytoplankton cells are very disperse. A plankton net is an excellent investment. Alternatively, concentrate tiny organisms in a large (2-5 litres) volume of water by collecting them over standard laboratory filter paper.

Culturing Cells. Almost all samples obtained directly from the wild can be greatly improved by culturing them for 7-10 days before a class. This is not difficult and is usually very rewarding in the classroom. We include at our Web site (cytographics.com) a page of simple procedures for culturing cells and mounting them for light microscopy.

Organisms Shown in the Video

Many of these organisms were recorded in preparations of mixed populations that had grown up from samples cultured for 7-14 days. Thus, the identity of individual species is often uncertain. If any viewer can offer confident identifications at the generic or species level, or  corrections to the list below, I would be most grateful to receive them. For locating individual sequences, Zero Time is set at the beginning of the very first opening sequence.

Unless otherwise indicated, sequences are shown in real time. Those sequences that were imaged in time-lapse have either of two designations in bold given in their description:

(i) an approximate duration of the original sequence in real time; or

(ii) the degree (e.g., 24X) to which the sequence has been speeded up.

 

Time Description of Organism/Sequence

00:58 A variety of euglenoid flagellates from a smelly pond, late summer.

01:04 Haematococcus: green algal flagellate, commonly growing as a reddish-green scum on transitory puddles, pools etc.

01:12 Gliding diatoms: Cymatopleura solea and 2 species of Surirella (25X).

01:18 Unidentified filose amoeba (25X).

01:21 The dinoflagellate Ceratium tenue. It has two flagella: one long and conspicuous, and a second, tightly coiled, which wraps around the middle of the cell.

01:26 Mixture of euglenoid flagellates plus a small unidentified gastrotrich (metazoan).

01:32 Phacus sp. (euglenoid flagellate)

01:46 Another Phacus sp. All euglenoid cells have a spiral body, a characteristic which is highly  exaggerated in this particular species.

01:53 Euglena acus (25X).

02:18 Trachelomonas armata. This genus of euglenoid flagellates all secrete an ornamented wall or "lorica" whose decoration is characteristic for each species.

02:26 Euglena (probably E. spirogyra). The wall ("pellicle") of euglenoid flagellates is composed of tough, usually flexible strips which can slide past one another during the contortions of the cell. In this species, the pellicular strips are decorated by tiny bumps. The red organelle is the eye-spot.

Quotation: "To be astonished is the first movement of the mind towards discovery." Louis Pasteur (1822-1895),  Address given December 7, 1854.

02:43 Large, unidentified amoeba (25X).

03:36 Same cell.

03:42 Another unidentified amoeba (50X).

03:53 An unusual reticulate amoeba which shows shuttle streaming in its cytoplasm. I have not encountered this organism described in the texts I have consulted; Leptomyxa appears to be the closest (25X).

04:03 Chlamydomonas (green algal flagellate: Volvocales).

04:19 Paramecium sp.

04:33 Trachelomonas sp.

05:15 Chlamydomonas: the orange-red organelle in the chloroplast is the eye-spot.

05:22 Trachelomonas (probably T. horrida), surrounded by other euglenoid flagellates.

05:35 The desmid Micrasterias hardeyi (green alga: Zygnematales).

05:38 Dictyocha octanaria. This is a silicoflagellate, a group of marine algae whose rather formless cytoplasm is able to create an elegant silica skeleton; in this species, it is a beautiful star shape.

05:42 This is one of the many bizarre ciliates and other strange cells that live exclusively in the gut of termites, where they assist in the digestion of wood fibres. This sequence taken by Sid Tamm is, I believe, of Koruga bonita.

05:49 Filopoid amoeba, possibly Nuclearia sp. (25X).

05:53 The dinoflagellate Gyrodinium britanicum. Although most dinoflagellates are photosynthetic and pigmented, many species like this one, are colourless and therefore heterotrophic, ingesting other cells (1/2X).

06:05 Trachelomonas sp.

06:13 Gonium sociale; colonial green alga (Volvocales).

06:29 Pandorina (probably P. morum); colonial green alga (Volvocales).

06:31 Pyrobotrys stellata; colonial green alga (Volvocales).

06:38 Stephanosphaera pluvialis; colonial green alga (Volvocales).

06:45                " ".

Quotation: "It is the eternal changefulness of life that makes it so beautiful." Sigmund Freud(1856-1939), "Familiar Medical Quotations" 1968.

07:06 The colonial dinoflagellate Alexandrium catenella (2X).

07:14 Eyespots of the colonial green flagellate Eudorina sp. (Volvocales).

07:20 Micractinium sp.: colonial green alga (Chlorococcales).

07:28 Colonial diatom Bacillaria paradoxa (5X).

07:49 Anthophysa (probably A. vegetans), a colourless colonial chrysophyte; the cells collectively secrete a stalk.

07:55 Volvox sp.: colonial green alga (Volvocales).

08:55 Leaf from the common garden plant Tradescantia sp.

09:08 Blue flower from Tradescantia.

09:39 Stamen hairs from flower, Tradescantia.

09:49 Cytoplasmic streaming in stamen hair cells.

10:00 Small amoeba, probably Hartmanella sp. (25X).

10:12 Unidentified blue/yellow flower.

10:23 Tiny flower (ca. 1 cm.) from floral spray of the orchid Dendrochilum longifolium.

11:11 Chromatophores (pigmented cells) from a scale of the squirrel fish Sargocentron seychellensis. The red cells are "erythrophores", the black cells "melanophores"; each of these cells disperses thousands of minute pigment particles in and out throughout the cytoplasm. Coordinated movement is controlled by the nervous system. (100X).

11:44 Explant from lung tissue of the newt Taricha granulosa (filmed overnight).

11:55 Cultured cells from newt lung tissue (100X).

12:02                    " "

Quotation: "Every cell comes from a cell." Rudolf Virchow (1858), Die Cellular pathologie in ihrer Begrundung auf physiologische und pathologische Gewebelehre. Berlin

12:21 Small amoeba dividing (25 mins.).

12:31 The desmid Arthrodesmus sp. dividing (green alga: Zygnematales) (2 hrs).

12:42 Two cells of Phacus sp., dividing (30 mins.).

12:57 The colonial diatom Thalassirosira sp. Cells are held together by a bundle of chitin filaments which are secreted to separate newly formed daughter cells (40 mins.) .

13:25 Newt lung cell undergoing mitosis and cleavage (1.5 hrs.).

13:37 The diatom Striatella unipunctata dividing (20 mins.).

13:52 Fertilized egg of the toad Xenopus laevis cleaving to form an embryo (filmed over about 8 hrs.).

14:30 Neural tube formation, embryo of Xenopus (about 45 mins.).

14:59 Development of head region and heart, embryonic tadpole of Xenopus (filmed over about six hours).

15:07 Developing tadpole, Xenopus (filmed over about 12 hrs.).

15:14 Young tadpoles.

15:35 Embryogenesis in Volvox carteri (green alga: Volvocales) (16 hrs.).

15:58 Inversion, during which the spherical colony turns completely inside-out.

16:08 Male sperm packets, V. carteri.

16:13 Colony formation over 24 hrs., Volvox sp.

16:25 Release of juvenile colonies, Volvox sp. (20 mins.)

16:38 Volvox sp.

Quotation: Ogden Nash
"Whales have calves,
Cats have kittens,
Bears have cubs,
Bats have bittens,
Swans have cygnets,
Seals have puppies,
But guppies just have little guppies."

16:57 Mouse oocyte with sperm attached to outer layer.

17:18 Fertilization in Oedogonium cardiacum (green algae: Oedogoniales) (4X).

7:32 Fertilization in Chlamydomonas; the moment of cell-cell connection through the fertilization tubule can be clearly seen.

17:46 Conjugation (fertilization) in the desmid Closterium sp. (green alga: Zygnematales) (6 hrs).

18:00 Conjugation and formation of the spiny zygospore in Cosmarium botrytis (desmid) (5 hrs.).

18:27 Cleavage, development of three eggs of Xenopus laevis (filmed over about 2 days).

Quotation: Richard Dawkins
"The problem that our explanation faces (is) the sheer hugeness of biological complexity and the beauty and elegance of biological design."

19:05 Colonies of Synura sp. (golden brown Chrysophyta).

19:50 Paramecium sp. feeding in a tangle of fungal hyphae.

Quotation: John Steinbeck, Sweet Thursday
"After all, I guess it doesn't matter whether you look down (through a microscope) or up (through a telescope) - as long as you look."

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