Developmental experiments for 6th, 7th and 8th grade classrooms
--Sarah Hake, maizesh@nature.Berkeley.EDU, Plant Gene Expression Center, USDA-ARS, 800 Buchanan St., Albany, CA

A) Epidermal impressions of maize leaves using superglue.

This easy and cheap experiment demonstrates how maize cells are in files, the presence of different cell types, including stomates, and differences between blade and sheath. It is good to do the experiment in comparison with some dicot leaves such as mint.
1) drop of glue on slide
2) place a piece of leaf on glue
3) wait a few minutes until glue dries, peel off leaf
4) examine under microscope

B) Pollen tube growth.

I have plated fresh pollen on media to examine pollen tube growth. In vitro pollen germination is described by D.B. Walden in The Maize Handbook.

C) Genetic segregation of Adh1 nulls.

This experiment can be used to demonstrate segregation ratios, gene activity and protein function. Each student has a few seeds from an ear that segregates for an Adh1 null and they slice a piece of the scutellum into a microtiter dish. They need to keep track of seed and slice. If they hold the seed in pliers, they don't run the risk of hurting themselves. A drop of adh1 activity stain is added to the microtiter dish and the dish is placed in the dark for 10 minutes. The appearance of the blue color is close to a miracle for most of the students. One of the controls can be absence of alcohol in the stain mixture. I have strains in which adh1 is linked to albinism. These seeds can then be planted, demonstrating genetic linkage.


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