A Low-Cost Computerized System to Monitor Running Performance and Circadian Rhythms of Twenty Mice Simultaneously.

This paper describes the design and functioning of a low-cost computerized system for monitoring the voluntary activity of mice in running wheels. The required software is written in Turbo Pascal(r) and provided via the Internet (http://www.eur.nl/fgg/ch1/rodent.html). The system accommodates the simultaneous monitoring of 20 animals over a virtually unlimited period. Two applications of the system are presented; one monitors the circadian rhythm of mice, and the other tests muscle strength and endurance.

A flow fluorimetric analysis of the cell cycle during growth and differentiation inDictyostelium discoideum.

We report a flow fluorimetric analysis of the DNA content of cells and nuclei from vegetative populations and various developmental stages of the cellular slime mouldDictyostelium discoideum using the dyes Hoechst 33258 and mithramycin. Nuclei from all of these populations showed an identical single DNA-content peak, indicating that most vegetative cells and most cells in all developmental stages are in one phase of the cell cycle. Our own data and findings in the literature indicate that this phase is G2. On the other hand, we also found that various stages, subpopulations of cells at early stages and the different differentiated cell types in the slug stage differ in DNA content per cell. Any particular population typically has one major peak of DNA content, with a modal value that is characteristic for the cell type and for the developmental stage. These differences presumably reflect differences in mitochondrial DNA content per cell.