Familiarization rodents

In general, rodents that have been exposed to an artificial odor during early life show an increased attraction to stimulus animals scented with that odor as adults. Increased odor preference following early exposure has been observed in female mice (Mainardi, Marsan and Pasquali 1965) and male rats (Marr and Gardner 1965). In some cases, this odor preference translates into increases in mating efficiency with females of the familiar scent. Specifically, male rats reared with citral-scented dams ejaculate faster when mating with citral-scented females compared to normal-scented females (Fillion and Blass 1986). 

Rodent visitation rates to odour stations decreased in the presence of predator faeces, compared to blank and novel odours. The response to different predators varied seasonally, and encompassed avoidance of familiar and unfamiliar faecal odours from marsupial and eutherian predators. This study supports the scat avoidance hypothesis (sensu Banks et al. 2003), which predicts that faeces are a useful indicator of predator presence, and I thus argue that, at least in the present context, faecal odours could be a good cue of predator presence for rainforest species. 

In addition to plaguing humans directly, flies spread pathogens that infect a significant number of plants and animals. Veterinary medicine must deal with horse flies and black flies, as well as pests with such curious names as warble flies and bot flies. There are ubiquitous stable flies that look like everyday house flies but deliver a painful bite, and a multitude of less familiar species that prey on sheep, rodents, and rabbits. Flies that are crop pests typically feed on their plant hosts as larvae. Seedcorn maggots, for... 

Strange as it sounds, the absence of odor often serves as a powerful stimulis unfamiliar and still unmarked objects or areas prompt vigorous scent marking. This applies to many mammals, including ungulates, such as pronghorn, Antilocapra americana (Muller-Schwarze et al, 1972) rodents, such as house mice, Mus musculus (Hurst, 1987), and carnivores (Kleiman, 1966). For example, pine martens, Maries martes, mark most consistently unmarked objects and do not mark objects that already carry their own odor. It is concluded that marking primarily serves familiarization. 

Preexposing rodents to the odor of a conspecific can alter the response to this individual when it is again encountered later, compared with responses to con-specifics whose odor is unfamiliar. For example, female brown lemmings, Lem-mus trimocrunatus, were experimentally exposed to the odor of a male. These females engaged in more contact social behavior with that now familiar male than females who had experienced odor from a different male or none at all. The males whose odor the females had experienced ejaculated more frequently than males under the other two conditions (Coopersmith and Banks, 1983). 

The behavior of tacl mice was also analyzed in several animal models of anxiety. The open-field test is a widely used tool for behavioral research, but less specific for the evaluation of the anxiety state of the animal, because it is a summation of the spontaneous motor and the exploratory activities, and only the latter is influenced by the anxiety level (Choleris et al. 2001). Under aversive environmental conditions (high level of illumination) the animals activity is strongly affected by the emotional state, while less aversive situations (familiar, dimly lit environment) are useful to assess the general motor activity of mice. Because rodents avoid open areas, the activity of mice in the central part of the open-field arena is inversely correlated to the anxiety level. Tad mice spent only 6.5% of their total activity in the central part, which represented 11% of the total field, indicating that they avoided this aversive area, hi contrast, tacl mice spent 13.6% of their activity in the central area (Bilkei-Gorzo et al. 2002). The increased central activity of the tad mice indicates that the test situation was anxiogenic for tad animals, but less so for the knockout mice. 

Step 1. Demonstrator and observer were maintained together with ad lib access to Purina Laboratory Rodent chow and water for a 2-day period of familiarization with both apparatus and cage-mate. 

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