Ch. 6— Alternatives to Animal Use in Research • 123 
Four advantages of using invertebrates in bio- 
medical research are: 
• different phylogenetic levels of structural and 
functional specialization can be exploited (e.g., 
different types of circulatory systems, novel 
chemical compounds); 
• invertebrates reproduce rapidly and produce 
numerous offspring; experiments can be exe- 
cuted in days and weeks instead of months 
and years; 
• storage, upkeep, and maintenance are inex- 
pensive; and 
• invertebrates are not prone to spreading dis- 
ease throughout a colony; 
The overwhelming disadvantage is the consid- 
erable phylogenetic distance between inverte- 
brates and humans. 
Mi cro- organisms 
From its origins within the medical disciplines 
of bacteriology, pathology, and virology, the study 
and use of micro-organisms has branched out to 
influence practically every area of biomedical re- 
search, as these examples indicate: 
• Salmonella typhimurium— bacteria used in 
mechanistic studies in genetics (124) as well 
as the Ames mutagenicity /carcinogenicity test 
(see ch. 8); 
• Escherichia coli— bacteria used by develop- 
mental biologists to derive theories of gene 
control (90) and by molecular biologists in re- 
combinant DNA research (75); 
• Streptococcus mutans— bacteria used in den- 
tal research on the metabolic activity of plaque 
(91); 
• Bacillus subtilis (bacteria) spores , Artemina sa - 
lina (brine shrimp) eggs, and Sordaria fimil- 
cula (fungi) ascospores— all incorporated into 
NASA's biostack (monolayers of biological test 
organisms sandwiched between thin foils of 
different types of nuclear track detectors) ra- 
diology experiments inside Spacelab I (31); 
• Tetrahymena pyriformis—a ciliate protozoan 
being used to study the effects of anesthetics 
on metabolism (44); and 
• a host of microscopic protozoans, metazoans, 
and rotifers used to investigate the physiol- 
ogy and biochemistry of photoreception and 
vision (4). 
The advantages of using micro-organisms in bio- 
medical research are fourfold: They reproduce 
rapidly at body temperature; rapid division (every 
20 to 30 minutes) makes them useful for short- 
term studies; multigenerational studies can be per- 
formed in a short period of time; and they are in- 
expensive in terms of storage, upkeep, and main- 
tenance. The major disadvantage stems from the 
fact that these are unicellular organisms : As a con- 
sequence, the interaction of cells cannot be stud- 
ied (156). 
Plants 
One advantage of using organisms from the plant 
kingdom is that they lack anything resembling a 
nervous system. Presumably, plants do not feel 
pain; they appear to be good potential alternatives 
to animals. Plants, like micro-organisms, are rela- 
tively easy and inexpensive to propagate (156). 
Although there is some interest in the potential 
use of plant cells in toxicology and oncology re- 
search (191), the use of whole cells from plants 
is obstructed by their very rigid cell-wall struc- 
ture compared with the relatively fluid animal cell 
membrane. This prevents their use in many dis- 
ciplines where intimate cell surface contact or 
transmembrane communication is essential. 
Once removed from the cell, comparable organ- 
elles from plants and animals (including micro- 
organisms) are essentially indistinguishable in both 
appearance and function. For example, in studies 
having potentially broad applications in endocri- 
nology and immunology, yeasts have been found 
to contain active steroid hormone systems (118). 
Yeast is used in cell biology in studies of the im- 
port of proteins into mitochondria, organelles that 
are essentially the same whatever their source 
(129). An extensive literature in cell biology, genet- 
ics, molecular biology, and virology supports the 
use of subcellular fractions from plants and ani- 
mals, separately or together, for research into basic 
molecular mechanisms (213). 
