China 
Africa 
Explore chapters and articles related to this topic
Antarctic Marine Biodiversity: Adaptations, Environments and Responses to Change
Published in S. J. Hawkins, A. J. Evans, A. C. Dale, L. B. Firth, I. P. Smith, Oceanography and Marine Biology, 2018
Another general mechanism that has received significant levels of research and support is the modulation of the composition of cell membranes. Alterations in lipid composition occur when temperature changes the optimum balance between flexibility and rigidity in the liquid-crystalline membrane bilayer and also between lipid phases including gel and crystalline, sometimes called lamellar and non-lamellar phases. The process of increasing levels of unsaturated fatty acids in membranes at lower temperature has been documented in species across the globe and is often seen in acclimation to temperature change. The general principle is that the levels of unsaturated fatty acids increase in cell membranes at lower temperature, a process called ‘homeoviscous adaptation’ (Dey et al. 1993, Hazel 1995). Increased levels of unsaturated fatty acids in cellular membranes have been reported for Antarctic fish (reviewed in Verde et al. 2006). Logue et al. (2000) studied membrane fatty acid composition in 17 species of fish from across the globe, including four from Antarctica (Pagothenia borchgrevinki, Trematomus bernacchii, Dissostichus mawsoni and Lycodichthys dearborni) and one from the sub-Antarctic South Georgia (Notothenia neglecta, now N. coriiceps). By assessing the fluorescence anisotropy of a probe (1,6-diphenyl-1,3,5-hexatriene), they identified that there was a high level of temperature compensation in membrane static order (a measure of fluidity or viscosity) in the Antarctic species. The membranes in the synaptosomes (neuronal synapses, or nerve cell junctions, isolated for research purposes) of the Antarctic fish were, however, less fluid than predicted from first principles, and temperature compensation was only partial and not complete. It may be that perfect compensation of membrane fluidity is not possible, and on this basis, low-temperature adaptation of many membrane related processes are, at best, imperfect. Data are very limited on the relative functioning of membrane associated processes versus those within the cell milieu, but the compensation of cytochrome c oxidase in the Antarctic eelpout is less well compensated for temperature than citrate synthase, which is not membrane associated (Hardewig et al. 1999a), and a similar imperfect adaptation of membrane related processes was also found for Arctic cod (Lucassen et al. 2006).
Intraspecies variability of fatty acid content and composition of a cosmopolitan benthic invertebrate, Gammarus lacustris
Published in Inland Waters, 2018
Olesia N. Makhutova, Svetlana P. Shulepina, Tatyana A. Sharapova, Anzhelika A. Kolmakova, Larisa A. Glushchenko, Elena S. Kravchuk, Michail I. Gladyshev
Phylogeny itself or together with diet is considered a key factor determining FA profiles of aquatic animals (Makhutova et al. 2011, Lau et al. 2012, Gladyshev et al. 2015). Among ecological factors, water temperature is one of the most studied. According to the hypothesis of “homeoviscous adaptation,” a decrease in ambient temperature leads to an increase in the percentages of PUFAs with comparatively low melting points to maintain cell membrane fluidity (Stillwell and Wassall 2003, Brett et al. 2009, Koussoroplis et al. 2013). The role of highly unsaturated FAs, such as EPA and DHA in temperature adaptation, is questionable, however, and is still under discussion (Hazel 1995, Gladyshev et al. 2015). The effect of salinity on the FA composition of aquatic animals is believed to manifest in changes of the percentages of omega-3 (n-3) and omega-6 (n-6) PUFAs (Fokina et al. 2010, Sarker et al. 2011, Fonseca-Madriqal et al. 2012). Numerous data on the importance of the influence of diets on FA composition of planktonic and benthic animals have been obtained, mainly under experimental conditions (Weers et al. 1997, Brett et al. 2006, Torres-Ruiz et al. 2010, Gladyshev et al. 2016a). Lau et al. (2013), however, studied FA variation in Asellus aquaticus (benthic isopod) across a nutrient gradient by combining a field study and laboratory experiments and showed a strong effect of dietary FAs on the PUFA composition of that isopod. The effect of other factors, for instance parasites or predation, has been much less studied or not studied at all.