Are mitochondria the main contributor of reactive oxygen species in cells? [COMMENTARY]
Yufeng Zhang and Hoi Shan Wong
Physiologists often assume that mitochondria are the main producers of reactive oxygen species (ROS) in cells. Consequently, in biomedicine, mitochondria are considered as important targets for therapeutic treatments, and in evolutionary biology, they are considered as mediators of life-history tradeoffs. Surprisingly, data supporting such an assumption are lacking, at least partially due to the technical difficulties in accurately measuring the level of ROS produced by different subcellular compartments in intact cells. In this Commentary, we first review three potential reasons underlying ...
Source: Journal of Experimental Biology - March 11, 2021 Category: Biology Authors: Zhang, Y., Wong, H. S. Tags: COMMENTARY Source Type: research
The high energetic cost of rapid force development in muscle [RESEARCH ARTICLE]
Tim J. van der Zee and Arthur D. Kuo Muscles consume metabolic energy for active movement, particularly when performing mechanical work or producing force. Less appreciated is the cost for activating muscle quickly, which adds considerably to the overall cost of cyclic force production (Chasiotis et al., 1987). But the cost magnitude relative to mechanical work, which features in many movements, is unknown. We therefore tested whether fast activation is costly compared to performing work or producing isometric force. We hypothesized that metabolic cost would increase with a proposed measure termed force-rate (rate of incre...
Source: Journal of Experimental Biology - March 11, 2021 Category: Biology Authors: van der Zee, T. J., Kuo, A. D. Tags: RESEARCH ARTICLE Source Type: research
Orexin-A inhibits fictive air breathing responses to respiratory stimuli in the bullfrog tadpole (Lithobates catesbeianus) [RESEARCH ARTICLE]
Elisa M. Fonseca, Tara A. Janes, Stephanie Fournier, Luciane H. Gargaglioni, and Richard Kinkead In pre-metamorphic tadpoles, the neural network generating lung ventilation is present but actively inhibited; the mechanisms leading to the onset of air breathing are not well understood. Orexin (ORX) is a hypothalamic neuropeptide that regulates several homeostatic functions, including breathing. While ORX has limited effects on breathing at rest, it potentiates reflexive responses to respiratory stimuli mainly via ORX receptor 1 (OX1Rs). Here, we tested the hypothesis that OXR1 facilitate the expression of the motor command ...
Source: Journal of Experimental Biology - March 11, 2021 Category: Biology Authors: Fonseca, E. M., Janes, T. A., Fournier, S., Gargaglioni, L. H., Kinkead, R. Tags: RESEARCH ARTICLE Source Type: research
Visual cues enhance obstacle avoidance in echolocating bats [RESEARCH ARTICLE]
Te K. Jones and Cynthia F. Moss Studies have shown that bats are capable of using visual information for a variety of purposes, including navigation and foraging, but the relative contributions of visual and auditory modalities in obstacle avoidance has yet to be fully investigated, particularly in laryngeal echolocating bats. A first step requires a characterization of behavioral responses to different combinations of sensory cues. Here we quantify the behavioral responses of the insectivorous big brown bat, Eptesicus fuscus, in an obstacle avoidance task offering different combinations of auditory and visual cues. To do ...
Source: Journal of Experimental Biology - March 11, 2021 Category: Biology Authors: Jones, T. K., Moss, C. F. Tags: RESEARCH ARTICLE Source Type: research
Distinct neuron phenotypes may serve object feature sensing in the electrosensory lobe of Gymnotus omarorum [RESEARCH ARTICLE]
Javier Nogueira, Maria E. Castello, Carolina Lescano, and Angel A. Caputi Early sensory relays circuits in the vertebrate medulla often adopt a cerebellum-like organization specialized for comparing primary afferent inputs with central expectations. These circuits usually have a dual output, carried by center ON and center OFF neurons responding in opposite ways to the same stimulus at the center of their receptive fields. Here we show in the electrosensory lateral line lobe of Gymnotiform weakly electric fish that basilar pyramidal neurons, representing ‘ON’ cells, and non-basilar pyramidal neurons, representi...
Source: Journal of Experimental Biology - March 11, 2021 Category: Biology Authors: Nogueira, J., Castello, M. E., Lescano, C., Caputi, A. A. Tags: RESEARCH ARTICLE Source Type: research
Polarization contrasts and their effect on the gaze stabilisation of crustaceans [RESEARCH ARTICLE]
Christian Drerup and Martin J. How Many animals go to great lengths to stabilise their eyes relative to the visual scene and do so to enhance the localisation of moving objects and to functionally partition the visual system relative to the outside world. An important cue that is used to control these stabilisation movements is contrast within the visual surround. Previous studies on insects, spiders and fish have shown that gaze stabilisation is achromatic (= ‘colour-blind’), meaning that chromatic contrast alone (in the absence of apparent intensity contrasts) does not contribute to gaze stabilisation. Follow...
Source: Journal of Experimental Biology - March 10, 2021 Category: Biology Authors: Drerup, C., How, M. J. Tags: RESEARCH ARTICLE Source Type: research
Evolved changes in maternal care in high-altitude native deer mice [RESEARCH ARTICLE]
Cayleih E. Robertson and Grant B. McClelland At high altitude (HA), unremitting low oxygen and persistent cold push small mammals close to their metabolic ceilings, leaving limited scope for aerobically demanding activities. However, HA breeding seasons are relatively short and endemic rodents compensate with larger litters than low altitude (LA) conspecifics. Rodent mothers are the sole source of heat and nutrition for altricial offspring and lactation is energetically costly. Thus, it is unclear how HA females balance energy allocation during the nursing period. We hypothesized HA female rodents invest heavily in each li...
Source: Journal of Experimental Biology - March 10, 2021 Category: Biology Authors: Robertson, C. E., McClelland, G. B. Tags: RESEARCH ARTICLE Source Type: research
When it's hot and dry: Life-history strategy influences the costs and cost-limiting strategies due to heat wave and water limitation [RESEARCH ARTICLE]
Sugjit S. Padda, Jordan R. Glass, and Zachary R. Stahlschmidt The frequency, duration, and co-occurrence of several environmental stressors, like heat waves and droughts, are increasing globally. Such multiple stressors may have compounding or interactive effects on animals, resulting in either additive or non-additive costs, but animals may mitigate these costs through various strategies of resource conservation or shifts in resource allocation. Through a factorial experiment, we investigated the independent and interactive effects of a simulated heat wave and water limitation on life-history, physiological, and behaviora...
Source: Journal of Experimental Biology - March 10, 2021 Category: Biology Authors: Padda, S. S., Glass, J. R., Stahlschmidt, Z. R. Tags: RESEARCH ARTICLE Source Type: research
An anti-narcolepsy drug reveals behavioral and fitness costs of extreme activity cycles in arctic-breeding songbirds [RESEARCH ARTICLE]
Wesley I. Payette, Brett L. Hodinka, Keelee B. Pullum, Melanie M. Richter, and Noah T. Ashley Sleep loss impairs cognitive function, immunological responses, and general well-being in humans. However, sleep requirements in mammals and birds vary dramatically. In circumpolar regions with continuous summer light, daily sleep duration is reduced, particularly in breeding birds. The effect of an anti-narcolepsy drug (modafinil) to putatively extend wakefulness was examined in two species of closely-related arctic-breeding passerine birds: Lapland longspurs (Calcarius lapponicus) and snow buntings (Plectrophenax nivalis). Free-...
Source: Journal of Experimental Biology - March 10, 2021 Category: Biology Authors: Payette, W. I., Hodinka, B. L., Pullum, K. B., Richter, M. M., Ashley, N. T. Tags: RESEARCH ARTICLE Source Type: research
Thresholds of polarization vision in octopus [RESEARCH ARTICLE]
In this study, the ability of octopus to detect polarization contrasts varying in angle of polarization (AoP) was investigated over a range of different degrees of linear polarization (DoLP) to better judge their visual ability in more ecologically relevant conditions. The ‘just-noticeable-differences’ (JND) of AoP contrasts varied consistently with DoLP. These JND thresholds could be largely explained by their polarization distance, a neurophysical model that effectively calculates the level of activity in opposing horizontally and vertically oriented polarization channels in the cephalopod visual system. Imag...
Source: Journal of Experimental Biology - March 10, 2021 Category: Biology Authors: Temple, S. E., How, M. J., Powell, S. B., Gruev, V., Marshall, N. J., Roberts, N. W. Tags: RESEARCH ARTICLE Source Type: research
Learning a non-neutral conditioned stimulus: place preference in the crab Neohelice granulata [RESEARCH ARTICLE]
Martin Klappenbach, Candela Medina, and Ramiro Freudenthal In the wild, being able to recognize and remember specific locations related to food sources and the associated attributes of landmarks is a cognitive trait important for survival. In the present work we show that the crab Neohelice granulata can be trained to associate a specific environment with an appetitive reward in a conditioned place preference task. After a single training trial, when the crabs were presented with a food pellet in the target quadrant of the training arena, they were able to form a long-term memory related to the event. This memory was evide...
Source: Journal of Experimental Biology - March 10, 2021 Category: Biology Authors: Klappenbach, M., Medina, C., Freudenthal, R. Tags: RESEARCH ARTICLE Source Type: research
Oxygen supply capacity breathes new life into the critical oxygen partial pressure (Pcrit) [RESEARCH ARTICLE]
We describe the α-method, in which the MR is monitored as oxygen declines and, for each measurement period, is divided by the corresponding PO2 to provide the concurrent oxygen supply (α0=MR/PO2). The highest α0 value (or, more conservatively, the mean of the three highest values) is designated as α. The same value of α is reached at Pcrit for any MR regardless of previous or subsequent metabolic activity. The metabolic rate needn't be constant (regulated), standardized, nor exhibit a clear-breakpoint at Pcrit for accurate determination of α. The α-method has several advantages ove...
Source: Journal of Experimental Biology - March 10, 2021 Category: Biology Authors: Seibel, B. A., Andres, A., Birk, M. A., Burns, A. L., Shaw, C. T., Timpe, A. W., Welsh, C. J. Tags: RESEARCH ARTICLE Source Type: research
The Murphy number: how pitch moment of inertia dictates quadrupedal walking and running energetics [RESEARCH ARTICLE]
Delyle T. Polet
Many quadrupedal mammals transition from a four-beat walk to a two-beat run (e.g. trot), but some transition to a four-beat run (e.g. amble). Recent analysis shows that a two-beat run minimizes work only for animals with a small pitch moment of inertia (MOI), though empirical MOI were not reported. It was also unclear whether MOI affects gait energetics at slow speeds. Here, I show that a particular normalization of the pitch moment of inertia (the Murphy number) has opposite effects on walking and running energetics. During walking, simultaneous forelimb and hindlimb contacts dampen pitching energy, favou...
Source: Journal of Experimental Biology - March 9, 2021 Category: Biology Authors: Polet, D. T. Tags: Comparative biomechanics of movement RESEARCH ARTICLE Source Type: research
Halyomorpha halys TAR1 characterization revealed its involvement in (E)-2-decenal pheromone perception [RESEARCH ARTICLE]
Luca Finetti, Marco Pezzi, Stefano Civolani, Girolamo Calo, Chiara Scapoli, and Giovanni Bernacchia In insects, the tyramine receptor 1 (TAR1) has been shown to control several physiological functions, including olfaction. We investigated the molecular and functional profile of the Halyomorpha halys type 1 tyramine receptor gene (HhTAR1) and its role in olfactory functions of this pest. Molecular and pharmacological analyses confirmed that the HhTAR1 gene codes for a true TAR1. The RT-qPCR analysis revealed that HhTAR1 is expressed mostly in adult brain and antennae as well as in early development stages (eggs, 1st and 2nd...
Source: Journal of Experimental Biology - March 9, 2021 Category: Biology Authors: Finetti, L., Pezzi, M., Civolani, S., Calo, G., Scapoli, C., Bernacchia, G. Tags: RESEARCH ARTICLE Source Type: research
Coronary blood flow influences tolerance to environmental extremes in fish [RESEARCH ARTICLE]
Daniel Morgenroth, Tristan McArley, Albin Gräns, Michael Axelsson, Erik Sandblom, and Andreas Ekström Approximately half of all fishes have, in addition to the luminal venous O2 supply, a coronary circulation supplying the heart with fully oxygenated blood. Yet, it is not fully understood how coronary O2 delivery affects tolerance to environmental extremes such as warming and hypoxia. Hypoxia reduces arterial oxygenation, while warming increases overall tissue O2 demand. Thus, as both stressors are associated with reduced venous O2 supply to the heart, we hypothesised that coronary flow benefits hypoxia and...
Source: Journal of Experimental Biology - March 9, 2021 Category: Biology Authors: Morgenroth, D., McArley, T., Gräns, A., Axelsson, M., Sandblom, E., Ekström, A. Tags: RESEARCH ARTICLE Source Type: research
