Available online
Description
The programme is about simple developmental patterns which occur in two organisms - an alga and an insect. The blue green alga Anabaena grows in long filaments of cells. At intervals along the fila...ment different cells develop. These are called heterocysts. The distance between heterocysts remains fairly constant and it is postulated that a chemical inhibitor gradient is established between developing hetexocysts and this gradient controls the position of new heterocyst development. The work on Anabaena is presented by Dr. Michael Wicox. Dr. Peter Lawrence describes his work on the cuticle patterns of the insect Rhodrzus. By effecting cuticle transplants in the larval stage of the insect he shows how its surface patterns may be modified. By studying these modified surface patterns a theory of chemical control by cellular gradients is put forward. The observations are supported by theoretical models. Dr. Norman Cohen in the closing minutes of the programme describes the procedure of moving a slime mould aggregate (Home Experiment).
The programme is about simple developmental patterns which occur in two organisms - an alga and an insect. The blue green alga Anabaena grows in long filaments of cells. At intervals along the fila...ment different cells develop. These are called heterocysts. The distance between heterocysts remains fairly constant and it is postulated that a chemical inhibitor gradient is established between developing hetexocysts and this gradient controls the position of new heterocyst development. The work on Anabaena is presented by Dr. Michael Wicox. Dr. Peter Lawrence describes his work on the cuticle patterns of the insect Rhodrzus. By effecting cuticle transplants in the larval stage of the insect he shows how its surface patterns may be modified. By studying these modified surface patterns a theory of chemical control by cellular gradients is put forward. The observations are supported by theoretical models. Dr. Norman Cohen in the closing minutes of the programme describes the procedure of moving a slime mould aggregate (Home Experiment).
| Item code: | S2-5; 04 |
|---|---|
| First transmission date: | 09-09-1973 |
| Published: | 1973 |
| Rights Statement: | |
| Restrictions on use: | |
| Duration: | 00:22:34 |
| + Show more... | |
| Producer: | Jim Stevenson |
| Contributors: | Norman Cohen; Peter Lawrence; Mike Wilcox |
| Publisher: | BBC Open University |
| Keyword(s): | Algae; Cellular gradients; Chemical control; Cuticle patterns; Developmental patterns; Heterocysts; Insect; Larval stage; Rhodnius; Theoretical models |
| Footage description: | Cohen introduces the programme. He discusses patterns of cell differentiation in development. Shots of a sponge skeleton, a daisy, a starfish, hair-pattern of a pig, a butterfly, dragonfly wings and eyes, cellular pattern of the retina All the above serve as examples of developmental patterns. Michael Wilcox discusses his work on developmental patterns in the alga Anabaena. Shot of Anabaena under magnification. Wilcox points out the heterocysts. Shots of Anabaena showing development of new heterocysts. Wilcox begins discussion on the subject of possible agents responsible for new heterocyst formation in Anabaena at the molecular level. He uses diagrams as aids. Wilcox speculates that a chemical inhibitor substance is responsible for heterocyst development. Animated graph shows zones of inhibitor concentration. Wilcox discusses problems of using this simple gradient model. Wilcox uses animated diagram to explain how anabaena overcomes the problems brought to light by the gradient model. Wilcox uses a static diagram to continue his explanation. Peter Lawrence begins his discussion on cuticle patterns of the insect Rhodnius. Lawrence places a live Rhodnius specimen on his hand. Close up shot of the insect. Lawrence with a Rhodnius larva mounted under the microscope. He cuts out a square of cuticle from the insect's abdomen, rotates it 180 degrees and replaces it. Lawrence uses models of Rhodnius abdominal cuticle to show the sort of operations he can perform. He demonstrates 3 different operations on the models. The resultant cuticle pattern changes after moulting are shown. Lawrence puts forward the theory that chemical control by cellular gradients is responsible for the modified surface patterns in Rhodnius cuticle. Animated diagrams aid. Lawrence uses a 3 dimensional model to demonstrate the validity of the theory. Computer animation shows the diffusion landscape for modified surface patterns in Rhodnius cuticle Lawrence sums up. Cohen describes the procedure for moving a slime mould aggregate. He demonstrates the making of a microneedle which is needed for this experiment. Cohen places a slime mould aggregate sample under the microscope. Shot of slime mould aggregate under magnification. Cohen uses the microneedle to shift the aggregate. |
| Master spool number: | 6HT/70946 |
| Production number: | 00525_1022 |
| Videofinder number: | 2824 |
| Available to public: | no |
