Seasonal Changes in Metabolism and Cellular Stress Phenomena in the Gilthead Sea Bream (Sparus aurata)

Abstract

Seasonal temperature changes may take organisms to the upper and lower limit of their thermal range, with respective variations in their biochemical and metabolic profile. To elucidate these traits, we investigated metabolic and antioxidant patterns in tissues of sea bream Sparus aurata during seasonal acclimatization for 1 yr in the field. Metabolic patterns were assessed by determining lactate dehydrogenase, citrate synthase, and β-hydroxyacyl CoA dehydrogenase activities, their kinetic properties and plasma levels of glucose, lactate, and triglycerides and tissue succinate levels. Oxidative stress was assessed by determining antioxidant enzymes superoxide dismutase, catalase, and glutathione reductase activities and levels of thiobarbituric acid reactive substances. Xanthine oxidase (XO) activity was determined as another source of reactive oxygen species (ROS) production. Furthermore, we studied the antiapoptotic protein indicator Bcl-2 and the apoptotic protein indicators Bax, Bad, ubiquitin, and caspase as well as indexes of autophagy (LC3B II/LC3B I and SQSTM1/p62) in the liver and the heart to identify possible relationships between oxidative stress and cell death. The results indicate clear seasonal metabolic patterns involving oxidative stress during summer as well as winter. During cold acclimatization, lipid oxidation is induced, while during increased temperatures, warm-induced metabolic activation and carbohydrate oxidation are observed. Thus, oxidative stress seems to be more prominent during warming because of the increased aerobic metabolism. The seasonal profile of apoptosis and XO as another source of ROS matches the results obtained in the laboratory and are interpreted within the framework of oxygen- and capacity-limited thermal tolerance.

Oxidative attack during temperature fluctuation challenge compromises liver protein homeostasis of a temperate fish model

“…From our results it seems that the total amount of liver polyubiquitinated proteins, which are in the way to be drive to the proteasome degradation system, was not altered after 50 days of cold exposure. This result would be in agreement with those obtained from cultured sea bream during the cold season (Feidantsis et al 2018).…”

“…observed to change during ER with respect C. At the end of the recovery time, ubiquitin tagging of high-molecular-weight proteins reverted, but fewer low-molecular-weight proteins were still destined to be recycled. Meanwhile Feidantsis et al 2018, in a seasonal trial in cages, reported a gradual increase of total ubiquitin conjugates from April to June in heart and liver due to increased metabolic activity. Again, more studies will be necessary to understand better the specific pattern of polyubiquitination with respect to protein molecular weight.…”

“…Specifically it is being affected by lipid accumulation (Gallardo et al 2003;Ibarz et al 2007a) and oxidant insult (Viarengo et al 1995;Abele and Puntarulo 2004;Ibarz et al 2010a;Feidantsis et al 2018;Sánchez-Nuño et al 2018a), exhibiting a lack of capacity to compensate intermediary metabolism to low temperatures (Ibarz et al 2003(Ibarz et al , 2007aSánchez-Nuño et al 2018a). Whereas metabolic response of liver to cold have been extensively studied, it is little known regarding to protein refolding and degradation pathways in the liver of Sparus aurata during exposure to low temperature and subsequent recovery.…”

Contrasting seasonal patterns of telomere dynamics in response to environmental conditions in the ectothermic sand lizard, Lacerta agilis

“…Given the potential causal chain from temperature through metabolism and ROS production to telomere erosion, ectotherm telomere dynamics should be particularly affected by climatic effects during the time of year when lizards are active and bask to elevate their body temperature 9,17,33 . Our results thus agree with our prediction that a higher temperature during activity would result in telomere attrition and are in agreement with some, but not all, studies.…”

“…During summer, reptiles experience a spike in metabolism on a daily basis, due to temperature shifts, which should result in oxidative stress when anti-oxidation is non-perfect 25,[32][33][34] and telomere erosion is expected to increase unless balanced by telomerase 35,36 . In contrast, in winter a reptile's activity is low due to low temperature and thus metabolism and oxidative stress should be correspondingly lower 4,33 . Similarly, weather variation between years could result in variation in activity patterns and metabolic rate and thus potentially alter telomere dynamics.…”