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The study was aimed to establish whether the chinchillas are susceptible to excessive dentition mineralisation and whether this may underlie reduced teeth wear. The analysis involved 14 chinchilla sculls, six showing excessive teeth growth and eight young and healthy animals. The sculls were visually examined and photographed; mandibles and teeth were subjected to mineral assay for the content of calcium, magnesium, and phosphates. The concentrations of calcium, magnesium, and phosphorus were lower in sick animals; the calcium-to-phosphorus ratio, on the other hand, was higher in sick chinchillas, and differed significantly from that in healthy animals. The level of phosphorus in the mandible was more than twice as high as that in other species of mammals. According to many authors, the excessive growth of teeth affecting farm chinchillas is probably due to a change in the diet in favour of low-protein feeds, which reduces the need to chew.
We investigated the effect of abdominal injections of 4 biogenic amines – serotonin (5-HT), dopamine (DA), octopamine (OA) and tyramine (TA) – on behaviour of workers of the red wood ant Formica polyctena in 4 types of aggression tests. The ants were observed during a 10 min encounter with a nestmate, a conspecifi c ant from an alien colony, a worker of another ant species (Formica fusca), and a small larva of the house cricket (Acheta domesticus). DA administration had the most important effect on ant aggressive behaviour. DA injections exerted a stimulatory effect on threats directed to F. fusca and to larvae of A. domesticus and on biting behaviour directed to larvae of A. domesticus. TA suppressed the frequency and the duration of biting behaviour directed to these larvae, although that effect was signifi cant only when the effects of TA were compared with those of DA and 5-HT. TA also reduced self-grooming behaviour, but only in tests with alien conspecifi cs. Other effects of biogenic amine administration included a stimulatory effect of OA on other active behaviour displayed by the ants during the tests with A. domesticus, inhibitory effects of 5-HT, OA and TA on allogrooming of a nestmate, and lenghtening of the latency to the fi rst antennal contact with a nestmate observed in TA and 5-HT-treated ants. The most important effects of biogenic amine administration were observed in the case of interactions of the ants with crickets. Support: grant MNiSW N N303 3075 33.
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