Seventy-four pairs of monozygotic (identical) twins and 35 pairs of dizygotic (fraternal) twins provided recognition thresholds (modified Harris-Kalmus test) for the sourness of citric acid and the saltiness of sodium chloride during the Twins Days Festival in Twinsburg, OH. Variance components (ACE) models were applied to the data: total variation = additive genetic (A) + common environment (C...

Novel chemical entities (NCEs) may be investigated for emetic liability in a range of unpleasant experiments involving retching, vomiting or conditioned taste aversion/food avoidance in sentient animals. We have used a range of compounds with known emetic /aversive properties to examine the possibility of using the social amoeba, Dictyostelium discoideum, for research into identifying and under...

Modern techniques offer an opportunity for a more complete evaluation of melanin production in the uvea and retinal pigment epithelium (RPE). By measuring the release of tritium from tritiated tyrosine in homogenized samples of adult bovine RPE as well as iris and choroid, tyrosinase activity could be demonstrated in both the uveal tract and the RPE. Phenylthiourea, a specific tyrosinase inhibi...

Previous work has demonstrated that SWR/J (SW) mice avoid phenylthiocarbamide (PTC) to a greater degree than C3HeB/FeJ mice in 48 h, two-bottle preference tests given in ascending series. The authors hypothesized, based also on previous work, that SW mice might form a conditioned taste aversion over time due to the toxic properties of PTC. We directly tested this hypothesis by attempting to con...

1. Twenty-eight pairs of monozygotic and eighteen pairs of dizygotic twins were tested for their ability to taste phenylthiocarbamide (P.T.C.) by the method of Harris & Kalmus (1949). 2. Much greater variance in threshold levels was detected within the DZ than within the MZ pairs and this confirms the genetic origin of most variation in ability to taste this substance. 3. Variance in threshold ...