Gnotobiotic Experiments Research Articles

Dental caries and plaque formation from diets containing sucrose or glucose in gnotobiotic rats infected with Streptococcus strain IB-1600.

1. Techniques were devised for the operation of a new small-scale gnotobiotic rat unit.2. The unit was then used to compare the cariogenicity of sucrose and glucose under carefully controlled conditions in the presence of a single strain of a streptococcus, as gnotobiotic experiments by other workers had given conflicting results.3. Streptococcus IB-1600 was implanted into thirty-four rats, which were then fed on high-sugar diets under gnotobiotic conditions for 5 or 8 weeks from weaning. The level of caries was significantly higher on the sucrose than on the glucose diet, but there was no significant difference in the extent of soft coronal dental plaque.

Eimeria tenella in Monoflora and Diflora Chicks

Eimeria tenella in Monoflora and Diflora Chicks

Comparison of sucrose and glucose in the causation of dental caries in gnotobiotic rats

Complete replacement of sucrose by glucose resulted in a higher incidence of dental caries in gnotobiotic rats inoculated with Lactobacillus casei, Streptococcus salivarius, Streptococcus faecalis, or Streptococcus FA-1. Caries was observed only in the occlusal sulci and there were no observable accumulations of dental plaque. A series of thirteen experiments was performed. There was considerable variation from one experiment to another. Mean scores of 18.0 were obtained in one experiment only to be followed by a mean score of zero although the same strain of rats, the same diet, and the same micro-organism were used in a repeat experiment. Biologic variation is a factor which must be considered even in gnotobiotic experiments.

Effect of Heterodera Schachtii On Sugar Beet Seedlings Under Monoxenic Conditions

In gnotobiotic (monoxenic) experiments, the damage to sugar beet seedlings inoculated with 1,000 and 10,000 Heterodera schachtii larvae varied directly with numbers of nematodes added, and inversely with age of seedlings at the time of inoculation. The effects produced were, 1) delayed and reduced seedling emergence, 2) stunting, 3) necrosis, and 4) infection of hypocotyls of pre-emergent seedlings. In hypocotyls and cotyledons typical giant cell formation and larval development to females was not observed, however. Symptoms in pre-emergent and young, post-emergent seedlings sometimes resembled those produced by other kinds of root and hypocotyl-infecting pathogens.