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Newborn rabbits rely on odour cues to localize and seize maternal nipples. In particular, they orally respond to the mammary
pheromone (MP) emitted in rabbit milk. The activity of the MP was so far mainly investigated in newborns, and a drop in its
releasing effect was shown in 23-day old pups. Here, we evaluated the activity of the MP in a large sample (n=1588) of domestic
rabbit pups tested between birth and weaning. We also assessed whether wild-type pups respond to the MP, and whether the developmental
course of their responsiveness matches the one of domestic pups. During the first postnatal week, the MP revealed to be a
strong releasing stimulus in all pups, regardless of their genetic and environmental background. However, the saliency of
the MP decreased with approaching weaning, and this decrease was clearly steeper in wild-type than in domestic pups. These
results are discussed with regard to the concept of ontogenetic adaptation and the effects of artificial selection. 相似文献
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Summary. Lactating rabbit females emit volatile odour cues that trigger specialized motor actions leading to sucking. But the activity
of these cues may change with advancing lactation. Here, we tested this possibility in three experiments. In Exp. 1, we assessed
whether 2-day-old pups respond differently to the odour of milk from females in early (day 2) as compared to late (day 23)
lactation. In Exp. 2, a compound bearing pheromonal properties, the Mammary Pheromone (MP), was dosed in these milks to assess
whether its concentration is correlated with behavioural activity. In Exp. 3, the responsiveness to a constant level of MP
was compared in d2 versus d23-pups. Run on 240 pups, the assays showed that a) the milk activity declines between d2 and d23
of lactation; b) during this same period, the concentration of the MP decreases in milk; c) the MP itself becomes less active
to elicit oral grasping in pre-weaning pups than in newborns. These results indicate that the MP is active during the period
when pups are exclusively dependent on milk. The convergent changes in emission and reception of this pheromone may sequentially
warrant that pups are first attracted to the mammae, and then that they progressively disinvest the mother as they begin to
eat solid food and to be attracted by other conspecifics. 相似文献
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Ammophila arenaria (marram grass) is the most important plant species for sand stabilization in European coastal foredunes. Stand degeneration
due to poor supply of wind-blown sand enhances the susceptibility for wind erosion when successional species do not become
established. ReplantedA. arenaria often fails to become established.
In the present study we examined whether management practices such as mowing, fertilizing, burning or below-ground cutting
of plants may be applied to re-establish the vigour ofA. arenaria. Field experiments performed at exposed sites, where naturally succeeding plant species are not supposed to become established
due to salt spray, showed that none of the applied methods resulted into enhanced tiller density ofA. arenaria. Thus, further studies are necessary to solve this type of management problem.
At the leeward side of foredunes, the successional speciesFestuca rubra ssp.arenaria andElymus athericus could be established successfully as both pre-grown seedlings and planted bundles of cuttings (all further experiments were
fertilized). When planted in spring, cuttings of successional plant species established less than those planted in early winter.
Water repellency of the sand surface is supposed to be the main cause for this. Pre-grown seedlings were less susceptible
for the season of planting. Direct sowing was not effective. Rabbit browsing had to be omitted to obtain successful establishment.
When living rhizomes of successional plant species were still present in the soil profile, fencing alone turned out to be
effective to re-establish vegetation at initially bare sites. 相似文献
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A. H. El‐Sebae M. H. Salem M. R. S. El‐Assar E. E. Enan 《Journal of environmental science and health. Part. B》2013,48(5):439-451
Abstract The present study was carried out to investigate the effect of Curacron (profenofos), Sumicidin (fenvalerate) and Dimilin (di‐fluobenzuron) on the in vitro rate of protein and RNA synthesis by rabbit liver and muscle tissues. The synthesis of protein and RNA were significantly stimulated in the liver and inhibited in the muscle by graded doses of these insecticides. Profenofos showed maximum effect on protein synthesis in both tissues at a dose of 0.2 μg/mL, while the maximum effect on RNA synthesis occurred at 0.2 μg/mL in the liver and at 2 μg/mL in the muscle. Fenvalerate caused maximum stimulation in both liver protein and RNA synthesis at a dose of 2 μg/mL, and maximum inhibition in the muscle at 10 and 0.2 μg/mL for protein and RNA synthesis respectively. The maximum effect of Dimilin on both tissues was reached at 5 μg/mL for protein synthesis and at 0.2 μg/mL for RNA synthesis. The effect of Dimilin on RNA synthesis was more pronounced in both tissues than its effect on protein synthesis, but this trend was reversed in the case of profenofos and fenvalerate. Present data also showed antagonism between these insecticides on the rate of protein and RNA synthesis. 相似文献
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