Mogensenkatz4640

Maximum force production varied isometrically with body mass. Falling and recovery flight with submaximal load represents a new context for evaluating limits to force production by flying animals.Hypoxia is common in aquatic environments, and exposure to hypoxia followed by reoxygenation is often believed to induce oxidative stress. However, there have been relatively few studies of reactive oxygen species (ROS) homeostasis and oxidative status in fish that experience natural hypoxia-reoxygenation cycles. We examined how exposure to acute hypoxia (2 kPa O2) and subsequent reoxygenation (to 20 kPa O2) affects redox status, oxidative damage, and antioxidant defenses in estuarine killifish (Fundulus heteroclitus), and whether these effects were ameliorated or potentiated by prolonged (28 day) acclimation to either constant hypoxia or intermittent cycles of nocturnal hypoxia (12 h normoxia 12 h hypoxia). Acute hypoxia and reoxygenation led to some modest and transient changes in redox status, increases in oxidized glutathione, depletion of scavenging capacity, and oxidative damage to lipids in the skeletal muscle. The liver had greater scavenging capacity, total glutathione concentrations, and activities of antioxidant enzymes (catalase, glutathione peroxidase) than the muscle, and generally experienced less variation in glutathiones and lipid peroxidation. Unexpectedly, acclimation to constant hypoxia or intermittent hypoxia led to a more oxidizing redox status (muscle and liver) and it increased oxidized glutathione (muscle). However, hypoxia acclimated fish exhibited little to no oxidative damage (as reflected by lipid peroxidation and aconitase activity), in association with improvements in scavenging capacity and catalase activity in muscle. Torin 2 in vitro We conclude that hypoxia acclimation leads to adjustments in ROS homeostasis and oxidative status that do not reflect oxidative stress but may instead be part of the suite of responses that killifish use to cope with chronic hypoxia.MicroRNAs (miRNAs) are small non-coding RNAs that negatively regulate gene expression and play roles in a wide range of physiological processes, including ontogenesis. Herein, we discovered a novel microRNA, novel miR-26, which inhibits translation of the phosphofructokinase (PFK) gene by targeting the 3' untranslated region (UTR) of pfk directly, thereby inhibiting the molting and body length growth of the freshwater shrimp (Neocaridina heteropoda). Lowering expression of the PFK gene by RNA interference (RNAi) led to a longer ecdysis cycle and smaller individuals. This phenotype was mirrored in shrimps injected with novel miR-26 agomirs, but the opposite phenotype occurred in shrimps injected with novel miR-26 antagomirs (i.e., the ecdysis cycle was shortened and body length was increased). After injection of 20-hydroxyecdysone (ecdysone 20E), expression of the novel miR-26 was decreased, while expression of the PFK gene was up-regulated, and the fructose-1,6-diphosphate metabolite of PFK accumulated correspondingly. Furthermore, expression of eIF2 (eukaryotic initiation factor 2) increased under stimulation of fructose-1,6-diphosphate, suggesting that protein synthesis was stimulated during this period. Taken together, our results suggest that the novel miR-26 regulates expression of the PFK gene and thereby mediates the molting and growth of N. heteropoda.We investigated how the exchange of sensory signals modulates the individual behaviors of juvenile crayfish in an anti-predatory context as well as during intraspecific agonistic encounters. We first compared crayfish housed in total sensory isolation or in pairs with access to chemical and visual cues. After 1 week of housing, we analysed their individual responses to a visual danger signal while they were foraging. We found that crayfish previously housed in pairs with exchange of sensory signals responded to a simulated predator attack predominantly with freezing behavior, whereas animals deprived of all sensory communication mostly responded by performing escape tail-flips. Next, we used the same housing conditions in between repeated fights in pairs of crayfish. Aggressive and submissive behaviors increased in subsequent fights both after total isolation and after exchange of olfactory and visual signals. Thus, unlike responses to simulated predator attacks, intraspecific agonistic behavior was not modulated by exposure to the same sensory signals. However, when we tested the effects of olfactory or visual communication independently, aggression increased dramatically after the exchange of olfactory signals, which also led to a high number of rank reversals in second fights, suggesting a destabilization of the original dominance relationship. Exposure to visual cues during the 1-week separation, however, produced the opposite effect, reducing agonistic behaviors and rank reversals. These findings demonstrate that exchange of sensory signals modulates future anti-predatory decision-making and intraspecific agonistic behaviors discretely, suggesting that the effect of these signals on shared neural circuitry is context dependent.Climate change is increasing the temperature variability animals face, and thermal acclimatization allows animals to adjust adaptively to this variability. While the rate of heat-acclimatization has received some study, little is known about how long these adaptive changes remain without continuing exposure to heat stress. This study explored the rate at which field-acclimatization states are lost when temperature variability is minimized during constant submersion. California mussels (Mytilus californianus) with different acclimatization states were collected from high- and low-zone sites (∼12°C vs. ∼5°C daily temperature ranges, respectively) and then kept submerged at 15°C for eight weeks. Each week, mussels' cardiac thermal performance was measured as a metric of acclimatization state; critical (T crit) and flatline (FLT) temperatures were recorded. Across eight weeks of constant submersion high-zone mussels' mean T crit decreased by 1.07°C from baseline, but low-zone mussels' mean T crit was unchanged. High- and low-zone mussels' mean maximum heart rate (HR) and resting HR decreased ∼12% and 35%, respectively.