Abstract: Newborn rabbits, Oryctolagus cuniculus, discriminate between different categories of adult conspecifics on the basis of their abdominal odour cues. Whether these cues can support the development of filial preferences has not been adequately tested. Using a two-choice paradigm, we assessed the ability of 3-8-day-old pups to orient selectively to the mother versus an unfamiliar female, either spontaneously or after odour conditioning. In experiment 1, nonconditioned pups roamed indifferently over the mother and an unfamiliar female. In experiment 2, pups conditioned to a neutral odorant while nursing or with the mammary pheromone became attracted by the odorant. In experiment 3, pups that had learned the odorant while nursing oriented for longer to any female carrying it, but the unscented mother and a scented unfamiliar female were equally attractive. Finally, in experiment 4, pups that had learned the odorant paired with the mammary pheromone showed a preference for their scented mother, but not systematically for a scented unfamiliar female; furthermore, they were equally attracted by the unscented mother and a scented unfamiliar female. In sum, pups did not spontaneously evince an olfactory preference for the mother when opposed to an unfamiliar female, although they seemed able to detect individual maternal odours. In fact, they appeared to react to both species-specific cues and individual cues that they had learned, and their responses depended on their degree of familiarity with the cues and on the context. The mammary pheromone by itself might act as both a releasing and a reinforcing signal in these early socially oriented behaviours.

Abstract: To elucidate the molecular mechanisms of red-green color vision in mammals, we have cloned and sequenced the red and green opsin cDNAs of cat (Felis catus), horse (Equus caballus), gray squirrel (Sciurus carolinensis), white-tailed deer (Odocoileus virginianus), and guinea pig (Cavia porcellus). These opsins were expressed in COS1 cells and reconstituted with 11-cis-retinal. The purified visual pigments of the cat, horse, squirrel, deer, and guinea pig have lambdamax values at 553, 545, 532, 531, and 516 nm, respectively, which are precise to within +/-1 nm. We also regenerated the “true” red pigment of goldfish (Carassius auratus), which has a lambdamax value at 559 +/- 4 nm. Multiple linear regression analyses show that S180A, H197Y, Y277F, T285A, and A308S shift the lambdamax values of the red and green pigments in mammals toward blue by 7, 28, 7, 15, and 16 nm, respectively, and the reverse amino acid changes toward red by the same extents. The additive effects of these amino acid changes fully explain the red-green color vision in a wide range of mammalian species, goldfish, American chameleon (Anolis carolinensis), and pigeon (Columba livia).