Fatty acid compostion and extreme temperature tolerance following exposure to fluctuating temperatures in a soil arthropod
Dooremalen, C. van; Suring, W. ; Ellers, J. - \ 2011
Journal of Insect Physiology 57 (2011)9. - ISSN 0022-1910 - p. 1267 - 1273.
membrane-lipid-composition - thermal-reaction norms - chill coma recovery - drosophila-melanogaster - homeoviscous adaptation - cycling temperatures - cold resistance - heat-resistance - plasticity - acclimation
Ectotherms commonly adjust their lipid composition to ambient temperature to counteract detrimental thermal effects on lipid fluidity. However, the extent of lipid remodeling and the associated fitness consequences under continuous temperature fluctuations are not well-described. The objective of this study was to investigate the effect of repeated temperature fluctuations on fatty acid composition and thermal tolerance. We exposed the springtail Orchesella cincta to two constant temperatures of 5 and 20 °C, and a continuously fluctuating treatment between 5 and 20 °C every 2 days. Fatty acid composition differed significantly between constant low and high temperatures. As expected, animals were most cold tolerant in the low temperature treatment, while heat tolerance was highest under high temperature. Under fluctuating temperatures, fatty acid composition changed with temperature initially, but later in the experiment fatty acid composition stabilized and closely resembled that found under constant warm temperatures. Consistent with this, heat tolerance in the fluctuating temperature treatment was comparable to the constant warm treatment. Cold tolerance in the fluctuating temperature treatment was intermediate compared to animals acclimated to constant cold or warmth, despite the fact that fatty acid composition was adjusted to warm conditions. This unexpected finding suggests that in animals acclimated to fluctuating temperatures an additional underlying mechanism is involved in the cold shock response. Other aspects of homeoviscous adaptation may protect animals during extreme cold. This paper forms a next step to fully understand the functioning of ectotherms in more thermally variable environments
Temperature-induced plasticity in membrane and storage lipid composition: Thermal reaction norms across five different temperatures
Dooremalen, C. van; Koekkoek, J. ; Ellers, J. - \ 2011
Journal of Insect Physiology 57 (2011)2. - ISSN 0022-1910 - p. 285 - 291.
fatty-acid-composition - orchesella-cincta collembola - homeoviscous adaptation - stress resistance - cold-acclimation - life-history - populations - physiology - evolution - responses
Temperature is a key environmental factor inducing phenotypic plasticity in a wide range of behavioral, morphological, and life history traits in ectotherms. The strength of temperature-induced responses in fitness-related traits may be determined by plasticity of the underlying physiological or biochemical traits. Lipid composition may be an important trait underlying fitness response to temperature, because it affects membrane fluidity as well as availability of stored energy reserves. Here, we investigate the effect of temperature on lipid composition of the springtail Orchesella cincta by measuring thermal reaction norms across five different temperatures after four weeks of cold or warm acclimation. Fatty acid composition in storage and membrane lipids showed a highly plastic response to temperature, but the responses of single fatty acids revealed deviations from the expectations based on HVA theory. We found an accumulation of C18:2n6 and C18:3n3 at higher temperatures and the preservation of C20:4n6 across temperatures, which is contrary to the expectation of decreased unsaturation at higher temperatures. The thermal response of these fatty acids in O. cincta differed from the findings in other species, and therefore shows there is interspecific variation in how single fatty acids contribute to HVA. Future research should determine the consequences of such variation in terms of costs and benefits for the thermal performance of species.