More than 20 different species were flown on the mission. American investigators conducted experiments on a subset that included rats, fruit flies, carrot tissue and cells, and fish eggs. A U.S. radiation dosimeter experiment was also carried out without using biological materials. A centrifuge on the spacecraft created an artificial 1-g environment for some of the biological subjects. Specimens rotated on the centrifuge were compared with specimens maintained in microgravity conditions. The general objective of the U.S. life science experiments was to compare the effects of microgravity and artificial gravity on the genetics, growth, development and aging of biological systems. Aging processes were studied using fruit flies as experimental subjects. The effects of microgravity, artificial gravity and the null-gravity environment of a ground-based clinostat were studied on carrot tumor growth. Another experiment using cultured carrot cells studied the development process in higher plants. A follow-up to an Apollo-Soyuz experiment was conducted to explore the harmful effects of microgravity on growth and development in fish eggs. Rat experiments were designed to assess microgravity effects on gastrointestinal, endocrine and lymphoid systems and on blood, muscle, bone and eye tissue. A radiation dosimetry experiment measured the high-linear energy transfer (LET) particle radiation aboard the biosatellite. Twenty-five unrestrained Wistar rats (Rattus norvegicus) were flown aboard the spacecraft, in individual cages. Body temperature telemetry transmitters were implanted in five of the rats. Two control groups of rats were studied on the ground - the Synchronous Control group and the Vivarium Control group. Studies on growth and development were conducted on one thousand embryos of Fundulus heteroclitus, a small shallow water minnow (Walbaum) of the Beaufort, North Carolina strain. Other experimental subjects included a Domodedovo-32 strain of the fruit fly Drosophila melanogaster, carrot (Daucus carota) tissue and cultured carrot cells.