Inexpensive and safe DNA gel electrophoresis using household materials.

Gel electrophoresis is the single most important molecular biology technique and it is central to life sciences research, but it is often too expensive for the secondary science classroom or homeschoolers. A simple safe low-cost procedure is described here that uses household materials to construct and run DNA gel electrophoresis. Plastic containers are fitted with aluminum foil electrodes and 9-V batteries to run food-grade agar-agar gels using aquarium pH buffers and then stained with gentian violet. This activity was tested in a high school biology classroom with significantly positive responses on postactivity reflective surveys. The electrophoresis activity addresses several Life Science Content Standard C criteria, including aspects of cell biology, genetics, and evolution. It also can be used to teach aspects of motion and force in the physical science classroom.

Molecular characterization of a Dictyostelium G-protein alpha-subunit required for development.

Dictyostelium discoideum utilizes G-protein-regulated transmembrane signaling systems to implement its developmental program. This report describes the Dictyostelium G-protein alpha-subunit, G alpha3, and demonstrates that it is required for normal development. G alpha3 is the largest of the four completely sequenced Dictyostelium G-protein alpha-subunits. The difference in size is due to variability in the N-terminal regions. The regions which are affected by the increased size of G alpha3 are the Gbeta gamma binding region and the helical domain that protects the guanine nucleotide cleft. g alpha3- mutants created by gene disruption fail to aggregate. However, when treated with exogenous pulses of cAMP that mimic the endogenous cAMP oscillations, they are able to aggregate, but development arrests at the tipped mound stage. This conditional developmental phenotype suggests that G alpha3 is required for production of the cAMP signal.