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Results for “longevity”

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PubMed2002

The Hydrobia ulvae-Maritrema subdolum association: influence of temperature, salinity, light, water-pressure and secondary host exudates on cercarial emergence and longevity.

The effects of environmental factors and exudates from the amphipod Corophium volutator on the emergence of Maritrema subdolum cercariae (Digenea: Microphallidae) from the snail Hydrobia ulvae were investigated in the laboratory. Increasing the temperature (15 to 25 degrees C) caused an overall 11-fold increase in emergence rate under varying salinities (24 to 36 per thousand). The effect of salinity depended on the experimental temperature. Emergence increased with increasing salinity at higher temperatures, but decreased with increasing salinity at 15 degrees C. Whereas the different levels of salinity had no effect, increasing the temperature significantly reduced the life span of cercariae. In comparison with complete darkness, light caused a two-fold increase in emergence, whereas an increment of the water pressure from 1.0 to 1.3 ATM (corresponding to 0 and 3 m of depth) left the shedding rate unaffected. Unidentified exudates from the second intermediate host, C. volutator, significantly depressed the cercarial emergence rate. The main transmission window of M. subdolum seems to occur during low water in tidal pools where light levels are high and solar radiation rapidly elevates the water temperature, as well as salinity through evaporation. The consequence of such a transmission strategy is discussed in relation to the impact of M. subdolum on the population dynamics of the second intermediate host.

Animals↗
PubMed1984

Social housing of rats: life-span effects on reaction time, exploration, weight, and longevity.

Sprague-Dawley rats were housed throughout their lives either in group cages or singly in standard laboratory cages. Locomotor activity was observed at selected ages and, in addition, operant conditioning procedures were used with an extensively trained subset of the animals to study reaction time and fixed ratio responding. The major effect of prolonged isolation was to induce timidity and inactivity during open field and emergence tests. Responding by isolates was depressed relative to socially-housed animals at 13 and 19 months of age although the higher levels of the social animals progressively declined during tests at 19 and 25 months. By comparison, neither housing condition nor age (7 to 25 months) systematically influenced the well-practiced operant responses (response rates, postreinforcement pauses, reaction times, foreperiod responses). A serendipitous finding was that isolated animals tended to die at earlier ages, an outcome that may be related to the fact that isolates also tended to weigh more throughout the experiment.

Age Factors↗
PubMed2000

Effects of microgravity and hypergravity on aging and longevity of insects.

The effects of microgravity and hypergravity on aging are still poorly documented, particularly in mammals. However, there is a growing interest for the use of the fruit fly, Drosophila melanogaster, and this species may be now considered as a model organism in gravitational biology studies dealing with aging.

Age Factors↗