Antioxidant Defenses in the Kidneys and Heart of the Freshwater Fish Astyanax lacustris Subjected to High (31°C) and Low (15°C) Temperatures

Ectothermic fish are directly affected by temperature changes in the environment. The aim of this study was to evaluate the metabolic responses in the gills of Yellowtail Lambari Astyanax lacustris under thermal stress. To this end, we used spectrophotometry to evaluate the biomarkers of carbohydrate and protein metabolism, antioxidant defense, and oxidative damage in fish subjected to low (15°C) and high (31°C) temperatures, with control groups held at 23°C, for 2, 6, 12, 24, 48, and 96 h. The results showed that cold thermal stress did not change the energy demand, and the antioxidant defense was reduced; therefore, the gills were vulnerable to the action of reactive oxygen species (ROS), presenting increased protein carbonylation at 12 h. With heat thermal stress, a higher energy demand was observed, which was verified by an increase in aerobic metabolism by glycolysis and the citric acid cycle. High-temperature stress also increased the antioxidant defenses, as verified by the increased activities of glutathione peroxidase, glutathione reductase, and glutathione S-transferase. However, the antioxidant defense system could not protect tissues from the action of ROS, as protein carbonylation increased at 6 and 24 h, indicating oxidative stress. The results showed that (1) temperature variations caused metabolic adjustments in the gills of Yellowtail Lambari, (2) the adaptive responses were different for winter and summer temperatures, and (3) Yellowtail Lambari recovered homeostasis when subjected to thermal stress, even with the occurrence of oxidative stress.

Although brassinosteroids (BRs) play crucial roles in plant development and stress tolerance, the mechanisms by which they have these effects are poorly understood. Here, we investigated the possible mechanism of exogenously applied BRs on reactive oxygen species (ROS), antioxidant defence and methylglyoxal (MG) detoxification systems in Ficus concinna seedlings grown under high-temperature (HT) stress for 48 h. Our results showed that the activities of ascorbate peroxidase (APX), superoxide dismutase (SOD), glutathione S-transferase (GST), glutathione peroxidase (GPX) and glyoxalase II (Gly II) were increased under two levels of HT stress. Compared with control the activities of catalase (CAT) and dehydroascorbate reductase (DHAR) were not changed due to HT stress. The activities of glutathione reductase (GR), monodehydroascorbate reductase (MDHAR) and glyoxalase I (Gly I) were increased only at moderate HT stress. Despite these protective mechanisms, HT stress induced oxidative stress in F. concinna seedlings, as indicated by the increased levels of ROS, malondialdehyde (MDA) and MG, and the reductions in chlorophyll levels and relative water content. The contents of reduced glutathione (GSH) and ascorbate (AsA) were not changed under moderate HT stress. Spraying with 24-epibrassinolide (EBR) alone had little influence on the non-enzymatic antioxidants and the activities of antioxidant enzymes. However, EBR pretreatment under HT stress resulted in an increase in GSH and AsA content, maintenance of high redox state of GSH and AsA, and enhanced ROS and MG detoxification by further elevating the activities of SOD, GST, GPX, APX, MDHAR, GR, DHAR, Gly I and Gly II, as evident by lower level of ROS, MDA and MG. It may be concluded that EBR could alleviate the HT-induced oxidative stress by increasing the enzymatic and non-enzymatic antioxidant defence, and glyoxalase systems in F. concinna seedlings.

Paclitaxel is a first-line chemotherapeutic with the major dose-limiting side effect of painful neuropathy. Previous preclinical studies indicate mitochondrial dysfunction and oxidative stress are associated with this disorder; however no direct assessment of reactive oxygen species (ROS) levels and antioxidant enzyme activity in sensory neurons following paclitaxel has been undertaken. As expected, repeated low doses of systemic paclitaxel in rats induced long-lasting pain behaviour with a delayed onset, akin to the clinical scenario. To elucidate the role of ROSinthe development and maintenance ofpaclitaxel-inducedpainful neuropathy, we have assessed ROS and antioxidant enzyme activity levels in the nociceptive system in vivo at three key behavioural time-points; prior to pain onset (day 7), peak pain severity and pain resolution. In isolated dorsal root ganglia (DRG) neurons, ROS levels were unchanged following paclitaxel-exposure in vitro or in vivo. ROS levels were further assessed in DRG and spinal cord in vivo following intrathecal MitoTracker®RedCM-H2XRos administration in paclitaxel-/vehicle-treated rats. ROS levels were increased at day 7, specifically in non-peptidergic DRG neurons. In the spinal cord, neuronally-derived ROS was increased at day 7, yet ROS levels in microglia and astrocytes were unaltered. In DRG, CuZnSOD and glutathione peroxidase (GPx) activity were increased at day 7 and peak pain time-points, respectively. In peripheral sensory nerves, CuZnSOD activity was increased at day 7, and at peak pain, MnSOD, CuZnSOD and GPx activity were increased. Catalase activity was unaltered in DRG and saphenous nerves. These data suggest that neuronally-derived mitochondrial ROS, accompanied with an inadequate endogenous antioxidant enzyme response, are contributory factors in paclitaxel-induced painful neuropathy.

Changes in river water temperatures are anticipated to have direct effects on thermal habitat and fish population vital rates, and therefore, understanding temporal trends in water temperatures may be necessary for predicting changes in thermal habitat and how species might respond to such changes. However, many investigations into trends in water temperatures use regression methods that assume long-term monotonic changes in temperature, when in fact changes are likely to be nonmonotonic. Therefore, our objective was to highlight the need and provide an example of an analytical method to better quantify the short-term, nonmonotonic temporal changes in thermal habitat that are likely necessary to determine the effects of changing thermal conditions on fish populations and communities. To achieve this objective, this study uses Bayesian dynamic linear models (DLMs) to examine seasonal trends in river water temperatures from sites located in the eastern and western United States, regions that have dramatically different riverine habitats and fish communities. We estimated the annual rate of change in water temperature and found little evidence of seasonal changes in water temperatures in the eastern U.S. We found more evidence of warming for river sites located in the western U.S., particularly during the fall and winter seasons. Use of DLMs provided a more detailed view of temporal dynamics in river thermal habitat compared to more traditional methods by quantifying year-to-year changes and associated uncertainty, providing managers with the information needed to adapt decision making to short-term changes in habitat conditions that may be necessary for conserving aquatic resources in the face of a changing climate.

Objective: To analyze the glutathione antioxidant defense system changes in the tear and serum of patients with hypertensive retinopathy (HR) and to establish whether there is an interdependence between their levels and HR degree. Methods: 90 patients were split into three groups according to the Keith-Wagner-Barker grading of HR: GI–36 patients; GII–35 patients; GIII–19 patients. The concentration of reduced glutathione (GSH) and activities of glutathione peroxidase (GPx) and glutathione reductase (GR) in tear and serum were measured. Results were analyzed by ANOVA, followed by Bonferroni post hoc test. The Spearman correlation coefficient was calculated (p≤0.05 statistically significant).Results: In serum, the GSH level and GPx activity were not statistically changed between groups with HR degree advancement, unlike the GR activity that was statistically diminished (p=0.018). The values of the studied markers in the tear showed a decrease with the progression of the HR degree. Only serum GSH level correlated with the tear one (r=-0.361, p=0.000), while the enzymes activity did not. A correlation of GPx and GR activity (r=0.417, p=0.000) was identified in tear, while in serum - of GPx activity and GSH level (r=409, p=0.000). Tear GPx and GR levels correlated significantly but with low power with HR degree (r=0.299, p=0.004/ r=0.299, p=0.004).Conclusion: Statistically significant elevation in tear GPx and GR activity and a tendency of GSH level increase was revealed, being attested, and a direct correlation between GPx and GR activity, as well as of their activity with the HR degree. In serum, the GSH level and the GPx activity did not change accurately, while the GR activity diminished significantly, the identified decrease being correlated with the HR degree. Abbreviations: HR = hypertensive retinopathy, HTN = hypertension, GSH = reduced glutathione, GPx = glutathione peroxidase, GR = glutathione reductase, GGR = gamma-glutamyl transferase, ROSs = reactive species of oxygen, OS = oxidative stress

Water temperature is an important ecological variable that affects the functioning of lakes. Unfortunately, for many lakes there are no long-term observations enabling the assessment of changes in water temperatures. This makes it difficult to include this aspect in research into the biology, ecology and chemistry of such lakes. This paper presents a literature review related to changes of surface water temperatures in lakes and in particular describing the response of water temperatures and stratification to changing climate in Polish lakes. On this basis, a model based on the available data on water temperature in 931 Polish lakes in the years 1951–1968 was proposed, which allows to estimate the baseline water temperature on any day of the year. This model is calculated using the complementary error peak function on the 0–3 m water temperature dataset, which provides the best reduction of diurnal temperature fluctuations. It can be an alternative to the average temperature of surface waters, which are calculated on the basis of systematically collected data. Based on the average water temperature data obtained from 56 thermal profiles in 10 lakes in 2010–2019, the equation was analogically calculated. The average monthly water temperatures in June, July, August and September and the change in water temperature (0.24–0.30 °C decade−1) in the period 1951–1968/2010–2019 were estimated then. Similar regional or single lake trends have been found in studies by other authors covering a similar or longer period of time. The proposed method, which is suitable for simulating temperatures, especially in summer, enables the determination of the value of changes in surface water temperature in Polish lakes when only thermal profiles data from different dates are available, which can be especially helpful when analyzing hydrobiological results.

Acute change in water temperature causes heavy economic losses in the aquaculture industry. The present study investigated the metabolic and molecular effects of acute thermal stress on black rockfish (Sebastes schlegelii). Gas chromatography time-of-flight mass spectrometry (GC-TOF-MS)-based metabolomics was used to investigate the global metabolic response of black rockfish at a high water temperature (27°C), low water temperature (5°C) and normal water temperature (16°C). Metabolites involved in energy metabolism and basic amino acids were significantly increased upon acute exposure to 27°C (P < 0.05), and no change in metabolite levels occurred in the low water temperature group. However, certain fatty acid levels were elevated after cold stress (P < 0.05), and this effect was not observed in the 27°C group, suggesting that acute high and low temperature exposures caused different physiological responses. Using quantitative real-time PCR, we analyzed the expression of ubiquitin (ub), hypoxia-inducible factor (hif), lactate dehydrogenase (ldh), and acetyl-CoA carboxylase (acac). Higher expression levels of ub, hif, and ldh (P < 0.05) were observed in the high water temperature group, but no changes in these expression levels occurred in the low water temperature group. Our findings provide a potential metabolic profile for black rockfish when exposed to acute temperature stress and provide some insights into host metabolic and molecular responses to thermal stress.

Based on the survey of the waters of Jiaozhou Bay in April and August 1981, this study examines the water temperature and horizontal distribution in the surface waters of Jiaozhou Bay. The results showed that in August and November, the variation range of water temperature in Jiaozhou Bay was 8.57–27.32°C, above 8.00°C, of which the interval length was 18.75°C. This indicates that in terms of water temperature changes, the water temperature in the entire waters of Jiaozhou Bay is relatively high in August and November, with more significant changes and a faster decrease. In August, the variation range of water temperature in Jiaozhou Bay was 25.19–27.32°C, of which the interval length was 2.13°C. In the northwestern coastal waters of Jiaozhou Bay, the water temperature reached 27.32°C. From the north to the south of the Bay, the variation range of water temperature was 25.19–27.32°C, of which the interval length was 2.13°C. In November, the variation range of water temperature in Jiaozhou Bay was 8.57–13.49°C, of which the interval length was 4.92°C. Outside the mouth of the Bay, a high-temperature zone was formed with a relatively high temperature of 13.49°C. From the north to the south of the Bay, the variation range of water temperature was 8.57–13.49°C, of which the interval length was 4.92°C. According to the variation of water temperature in Jiaozhou Bay, three factors influencing water temperature changes have been proposed: 1) total solar radiation energy; 2) air condition; and 3) water depth. These three factors influence changes in water temperature. In addition, a mechanism for the variation in water temperature has been suggested: 1) In June, the total solar radiation energy is the strongest, while it is weaker in December. As the total solar radiation energy increased, its heat to seawater increased. When the air temperature was higher than the water temperature, the air conduction transferred more and more heat to the surface seawater. When the water depth is small, the water temperature increases quickly; alternatively, the water temperature rises slowly when the water depth is large. Thus, the variation of total solar radiation energy, air conduction, and water depth determined the rise in water temperature. 2) In June, the total solar radiation energy is the strongest, while weaker in December. As the total solar radiation energy decreased, the heat supplied by solar radiation energy to seawater decreased. When the air temperature was lower than the water temperature, cold energy was transferred by the air conduction to the surface seawater. As the temperature becomes lower and lower than the water temperature, more cold energy is transferred through the air conduction to the surface seawater. When the water depth is small, the water temperature declines quickly; alternatively, when the water depth is large, the water temperature declines slowly. Thus, the variation of total solar radiation energy, air conduction, and water depth determined water temperature decline. Moreover, this study further confirmed the following: 1) The total radiation energy of the sun provides heat, but the amount of heat provided is different. 2) Both heat and cold energy can be transferred to surface seawater by air conduction. 3) Water depth determines the speed of changes in water temperature.

The present paper shows analysis of water level (the distance from the land surface to the water in the well under static condition) and water temperature observed at three different levels of Chuan no. 03 well to study the changes associated with the Wenchuan earthquake of 2008 and the 2011 Tohoku-Oki earthquake. Our analysis shows co-seismic changes in water level and water temperature associated with the increase in compressive stress associated with the Wenchuan earthquake. The water level shows an increase, whereas there was drop in water temperature at the shallow depth (395 m) and enhancement of water temperature at the middle (595 m) and the bottom (765 m) layers. However, no step change in water level or temperature of Chuan no. 03 well is observed associated with the Tohoku-Oki earthquake, only seismic wave propagation-induced water level oscillation and led to co-seismic response of water temperature. The analysis of the co-seismic responses and post-earthquake adjustment processes combined with the borehole histogram and the borehole temperature gradient data clearly show co-seismic changes in water temperature that could be closely associated with the changes in the regional stress and strain state and the distribution of the aquifer and the characteristics of the aquifer. The observed temperature variation of different layers in the borehole is likely to be controlled by the flow of water in the horizontal direction.

1. The idea of the inflection point of water temperature, d2T/dt2 (here, T: temperature and t: time), was applied to an analysis on the correlation between the feeding activity of goldfish and the changes of water temperature, especially taking into consideration both the time factor in the biological clock of the fish and the stimulus of water temperature for fish feeding. The results thus obtained were compared with those obtained by the use of the average water temperature and the coefficient of water temperature variation respectively. 2. The experiments were carried out for five to seven consecutive days a month during the period from March 1957 to February 1958, at the greenhouse of the Faculty of Fisheries, Hokkaido University. Feeding activity of the goldfish was recorded by an automatic feeding apparatus. For measuring the water temperature an automatic recording thermometer was used. 3. Feeding activity of the goldfish almost ceased under the condition of water temperature below 7 or 8°C. A plus correlation between the total daily feeding frequency and the average daily water temperature was clearly found so far as the water temperature ranged from about 9 to 25°C. However, even if in two consecutive days the average daily water temperature was almost the same, it was not rare that the feeding activities for the two days were found to be clearly different from each other; generally, more active feeding was recorded on a day when the coefficient of water temperature variation was larger. So, it is presumable that in such a case changes of the water temperature with high fluctuation accelerated the feeding activity as stimuli for the fish. 4. Throughout the present experiment, almost all of the daily feeding was found to be recorded at the time of the rising phase of water temperature, that is, the temperature showed the plus value in its changing rate (C°/Hr). In both the autumn and spring months, the maximum feeding frequency was often found to occur at just the time of the inflection point of water temperature. Especially, in late autumn as the water temperature fell, the peak of the feeding was found to correspond clearly with the time of the inflection point of water temperature. In the summer months, however, such a tendency was found to be very rare. 5. It seems that when the fishes were acclimatized to a relatively high temperature, the effect of change of the water temperature on fish feeding was rather inconspicuous, but when the fishes have adapted to the condition of low temperature such as in late autumn, they became more sensitive even to a slight change of the water temperature as a strong stimulus. Generally speaking, however, the peak of the fish feeding is found to occur at the time of the inflection point of water temperature. Such an idea of the inflection point may be applied also to any ecological and physiological studies.

Based on the survey materials of the waters of Jiaozhou Bay in April and August 1981, this article studies the water temperature and horizontal distribution in the surface waters of Jiaozhou Bay. The results have showed that the water temperature ranged within 7.52–30.90°C in April and August, and the length of interval of water temperature was 23.38°C. The water temperature of the ocean was above 7.00°C. It indicated that the water temperature of the entire water body of Jiaozhou Bay was relatively high in April and August, in terms of the changes of water temperature. In April, the water temperature in the water body of Jiaozhou Bay ranged within 7.52–13.70°C, and the length of temperature interval was 6.18°C. In Jiaozhou Bay, from the northeastern coastal waters along the northern coastal waters to the northwestern coastal waters, the range of water temperature changes was 12.82–13.70°C, and the interval length of seawater temperature changes was 0.88°C. From the northern area to the southern area, the range of water temperature changes was 7.52–13.70°C, and the interval length of seawater temperature was 6.18°C. In August, the range of water temperature changes was 24.60–30.90°C, and the interval length of seawater temperature was 6.30°C. In the eastern area of Jiaozhou Bay, the water temperature in the coastal waters of the estuary of Jiaozhou Bay was 30.90°C, forming a high temperature area. In the coastal waters of Jiaozhou Bay from the northwest to the north, the range of water temperature changes was 27.32–27.37°C and the interval length of seawater temperature was 0.05°C. In April and August, the increase of water temperature in the coastal waters from the northeast along the north to the northwest of Jiaozhou Bay was mainly caused by the shortwave radiation from the sun and sky and the longwave radiation from the atmosphere which continuously offered heat to the seawater. In April, it formed a circular water area with low temperature centered with the central water area of Jiaozhou Bay, whose water temperature ranged within 7.52–8.51°C. Thus, there was no heat source to provide heat to the central waters of Jiaozhou Bay, resulting a loop-locked low water temperature area in the center of the bay. In August, in the eastern part of Jiaozhou Bay, that is, the coastal waters in the estuary of Haibo River, the water temperature reached a relatively high value, 30.90°C. The source of the increase in water temperature was the transportation of heat from Haibo River, which transferred the heat of the river to the surface seawater.

This experiment was carried out to confirm the role of water level and water temperature in inducing the spawning of tropical walking catfish. Mature males and females reared under 23 - 25 °C, were paired and induced to spawn by controlling water level and water temperature. Decreasing water level and returning it to its original level resulted in a low spawning rate (less than 6.7 %) at 23 °C. Decreasing water level with simultaneous increase in water temperature, followed by returning the respective levels to their originals gave high spawning rates (41.7 — 50 %); whereas the same treatment but without any water temperature decreased when the water level was returned to the initial level, gave a low spawning rate (16.7 %). Increasing water level only, failed to induce spawning. A high spawning rate was obtained also when changes in water level were carried out under high temperature of 28 °C. No fish spawned in the absence of the environmental stimulation. From the results, it is confirmed that water level and temperature play important roles in inducing spawning of tropical walking catfish. Changes in water temperature probably increase the sensitivity of fish to the change in water level. Prolonged exposure to high water temperature could also improve the sensitivity of fish. Key words: Walking catfish / spawning / water level / water temperature

An integrated analysis of transcriptome and metabolome to reveal the effects of temperature stress on energy metabolism and physiological responses in Schizothorax wangchiachii muscles

Morphological performance of invasive plants can be determined by abiotic factors (e.g.water temperature) and biotic factors (e.g.herbivory). This study investigates the performance of an exotic plant in its native and introduced environments. The questions of study are: Is the performance ofEgeria densain both its native and introduced areas associated with abiotic and/or biotic factors? Is the performance of this plant better in the native or in the introduced area? In order to answer these questions,E. densaindividuals collected in France (introduced range) were compared with individuals collected in Brazil (native range). The results demonstrate thatE. densapopulations sampled in its native areas included a higher percentage of plants grazed than in the introduced range populations, but they also exhibited a superior performance in terms of length and dry mass. In both regions, the performance of the plants was associated mainly with abiotic factors. Whereas the higher temperature in its native area may have promoted greater growth in terms of length and dry mass, a lower temperature and high levels of ammonium in French waters might have reduced the development of this plant in its introduced range. The lower performance ofE. densain France should not be associated with abiotic factors alone, since other factors can also be involved, as limited resources or low clonal adaptation. Thus, future studies concerningE. densaperformance in France should consider these factors in order to assist in understanding the nature of the plant’s invasiveness in this region.

The resistance to physical stresses by Penaeus monodon juveniles fed diets supplemented with astaxanthin