Issues

Summary: This Commentary highlights the distinction between biochemical and biological definitions of oxidative stress, discusses issues to consider when designing experiments to investigate oxidative stress, and proposes the ‘redox signalling hypothesis’ of life history.

Highlighted Article: Low-output infrequent calls in baleen whale mother–calf pairs may mediate contact between mother and calf, while decreasing the risk of detection by potential predators.

Summary: Muscle can be a motor (work output) or a brake (work absorption), or can simply exert force; these functions and their costs are relevant to locomotion. This versatility is revealed by a varying stimulation pattern.

Highlighted Article: Chewing in a freshwater stingray includes overbite cycles that exert shear forces on the food in a manner convergent with mammalian mastication.

Highlighted Article: The stereotyped difference in elbow angle between walking and running in humans is linked to a mechanical tradeoff between shoulder and elbow muscle torque.

Summary: The intestinal hormone guanylin is shown to stimulate bicarbonate secretion into the lumen through NKCC2 inhibition and precipitate high Ca/Mg ions in seawater in the eel intestine, which enhances water absorption and promotes seawater adaptation.

Summary: Functional characterization of a vertebrate-type calcitonin signalling system in a protostome.

Summary: Larval zebrafish are able to regulate their hypoxic ventilatory response, which significantly contributes to overall oxygen uptake under hypoxic conditions.

Summary: The switch between diapause and direct development results in developmental pre-diapause plasticity in life history and metabolism but not in reserve accumulation in a seasonally polyphenic butterfly.

Summary: Hornet queens, drones and workers have excellent olfactory learning that can persist for up to 30 days in queens and drones.

Summary: Hummingbird hawkmoths use optic flow similarly to flies and bees to control their position, but not their speed, in flight tunnel experiments.

Summary: Gene expression biomarkers associated with salinity stress and thermal stress, but not hypoxic stress, exist in salmon gill tissue. Biomarkers were also associated with mortality.

Summary: Alcids accelerate during both the upstroke and downstroke when swimming in shallow water, contrary to previous kinematic studies, but head stabilization limits the detectability of the true stroke–acceleration pattern.

Summary: Models for acid-base regulation by the goldfish kidney based on SIET measurements indicate a major role for proximal tubules in H⁺ secretion and HCO₃⁻ reabsorption, in contrast to HCO₃⁻ reabsorption and NH₃/NH₄⁺ secretion in distal and connecting tubules.

Summary: Increasing the magnitude of stretch results in a greater stretch–shortening cycle effect and an increased force at steady state following the stretch, probably because of the greater residual force enhancement.

Summary: Exposure to infochemicals from crushed conspecifics and heterospecifics alters embryonic developmental time, size and morphology of the first larval instar in a palaemonid shrimp, indicating that alarm cues are conserved in this taxon, providing embryos with an innate recognition of alarm cues.

Highlighted Article: Pectoralis muscle SERCA activity increased as blackbird nestlings reached thermal independence, but declined at older ages, possibly owing to adaptive muscle remodeling. There was no effect of diet on SERCA activity.

Summary: Investigation of calcified tube growth of Serpulidae under low-pH conditions indicates that ocean acidification will negatively affect the initiation and persistence of both biofouling and epiphytic polychaete tube worms.