Quality control of mitochondria during aging: Is there a good and a bad side of mitochondrial dynamics?

Maintenance of functional mitochondria is essential in order to prevent degenerative processes leading to disease and aging. Mitochondrial dynamics plays a crucial role in ensuring mitochondrial quality but may also generate and spread molecular damage through a population of mitochondria. Computational simulations suggest that this dynamics is advantageous when mitochondria are not or only marginally damaged. In contrast, at a higher degree of damage, mitochondrial dynamics may be disadvantageous. Deceleration of fusion‐fission cycles could be one way to adapt to this situation and to delay a further decline in mitochondrial quality. However, this adaptive response makes the mitochondrial network more vulnerable to additional molecular damage. The “mitochondrial infectious damage adaptation” (MIDA) model explains a number of inconsistent and counterintuitive data such as the “clonal expansion” of mutant mitochondrial DNA. We propose that mitochondrial dynamics is a double‐edged sword and suggest ways to test this experimentally.     

Is there a circadian rhythm of postural control and perception of the vertical?

Daytime activity is largely regulated by the day/night pattern. Various physiological and cognitive functions display a variation during the diurnal period, where individuals manage their balance, spatial orientation and consequently their perception of the vertical. However, findings concerning daytime changes of postural control quality remain contradictory, mainly due to methodogical considerations. The aim of our study is to evaluate the effect of time of day on postural control and perception of the vertical.

Fifteen male subjects underwent six test sessions over a 24-hour period. Each session involved a postural balance test (static/dynamic; eyes open/closed) and a subjective evaluation of sleepiness, fatigue and subjective visual vertical (SVV) (light stick tilted from 10 to 40°; eight trials). No time-of-day effect was observed on postural balance. However, perception of the vertical fluctuates during the day and is better at 10 a.m. than at 10 p.m. Despite the gradual perception of the vertical deterioration over the day, postural balance does not show any fluctuation. This postural balance consistency throughout the day may be the result of compensation mechanisms.     

Is there an association between variables of postural control and strength in adolescents?

Is there an association between variables of postural control and strength in adolescents? The risk of sustaining sport injuries is particularly high in adolescents. Deficits in postural control and muscle strength represent 2 important intrinsic injury risk factors. Therefore, the purpose of this study was to investigate the relationship between variables of static and dynamic postural control and isometric and dynamic muscle strength and to find out whether there is an association between measures of postural control and muscle strength. Twenty-eight adolescents participated in this study (age 16.8 ± 0.6 years; body mass index 20.5 ± 1.8 kg · m(-2)). Biomechanic tests included the measurements of maximal isometric leg extension force (MIF) and rate of force development (RFDmax) of the leg extensors on a leg press with the feet resting on a force platform, vertical jumping force, and height (countermovement jump [CMJ]) on a force plate and the assessment of static (1-legged stance on a balance platform) and dynamic (mediolateral perturbation impulse on a balance platform) postural control. The significance level was set at p < 0.05. No significant associations were observed between measures of static and dynamic postural control. Significant positive correlations were detected between variables of isometric and dynamic muscle strength with r-values ranging from 0.441 to 0.779 (p < 0.05). Based on these models, a 100-N increase in MIF of the leg extensors was associated with 3.9, 4.2, and 6.5% better maximal CMJ force, CMJ height, and RFDmax, respectively. No significant correlations were observed between variables of postural control and muscle strength. The nonsignificant correlation between static/dynamic postural control and muscle strength implies that primarily dynamic measures of postural control should be incorporated in injury risk assessment and that postural control and muscle strength are independent of each other and may have to be trained complementary for lower extremity injury prevention and rehabilitation purposes.     

Biology and natural enemies of Cydalima perspectalis in Asia: Is there biological control potential in Europe?

The box tree moth, Cydalima perspectalis (Walker) (Lepidoptera: Crambidae), a native pest of box trees (Buxus spp.) in Asia, was first detected in Germany and the Netherlands in 2007 and has since rapidly spread throughout Europe causing severe damage to ornamental and native box trees. To date, sustainable control strategies for C. perspectalis in Europe are lacking, primarily owing to the inadequate information regarding the biology and the ecology of this recent invader. Several studies conducted in Asia, however, may provide important information for the development of management strategies against C. perspectalis, which are urgently needed to preserve the natural box tree forests in Europe. The current literatures on the biological characteristics, host plants, phenology, distribution and control options of the box tree moth in Asia are reviewed, preliminary data on the parasitism of C. perspectalis in Europe are provided, and options for sustainable long‐term solutions for the management of the invasive pest in Europe are discussed.     

Is the spring quality of muscle plastic?

During locomotion, major muscle groups are often activated cyclically. This alternate stretch-shorten pattern of activity could enable muscle to function as a spring, storing and recovering elastic recoil potential energy. Because the ability to store and recover elastic recoil energy could profoundly affect the energetics of locomotion, one might expect this to be an adaptable feature of skeletal muscle. This study tests the hypothesis that chronic eccentric (Ecc) training results in a change in the spring properties of skeletal muscle. Nine female Sprague-Dawley rats underwent chronic Ecc training for 8 wk on a motorized treadmill. The spring properties of muscle were characterized by both active and passive lengthening force productions. A single "spring constant (Deltaforce/Deltalength) from the passive length-tension curves was calculated for each muscle. Results from measurements on long heads of triceps brachii muscle indicate that the trained group produced significantly more passive lengthening force (P = 0.0001) as well as more active lengthening force (P = 0.0001) at all lengths of muscle stretch. In addition, the spring constants were significantly different between the Ecc (1.71 N/mm) and the control (1.31 N/mm) groups. A stiffer spring is capable of storing more energy per unit length stretched, which is of functional importance during locomotion.     

Is there an association between variables of postural control and strength in prepubertal children?

The risk of sustaining falls and sports-related injuries is particularly high in children. Deficits in balance and muscle strength represent 2 important intrinsic fall and injury-risk factors. Therefore, the purpose of this study was to investigate the relationship between variables of static and dynamic postural control and isometric and dynamic muscle strength and to find out whether there is an association between measures of postural control and muscle strength in prepubertal children. Thirty children participated in this study (age 6.7 ± 0.5 years; body mass index 16.0 ± 1.8 kg·m(-2)). Biomechanic tests included the measurements of maximal isometric torque and rate of force development (RFD) of the plantar flexors on an isokinetic device, jumping power and height (countermovement jump [CMJ]) on a force plate, and the assessment of static and dynamic posture during bipedal stance on a balance platform. The significance level was set at p < 0.05. No significant associations were observed between variables of static and dynamic postural control. Significant positive correlations were detected between the RFD of the plantar flexors and CMJ height (r = 0.425, p < 0.01). No statistically significant associations were found between measures of postural control and muscle strength. The nonsignificant correlations between static and dynamic postural control and muscle strength imply that primarily dynamic measures of postural control should be incorporated in fall and injury-risk assessment and that postural control and muscle strength appear to be independent of each other and may have to be trained in a complementary manner for fall and injury-preventive purposes.     

Is there a biology of quantum information?

This paper briefly considers the notion of a biology of quantum information from a number of complementary points of view. We begin with a very brief look at some of the biomolecular systems that are thought to exploit quantum mechanical effects and then turn to the issue of measurement in these systems and the concomitant generation of information. This leads us to look at the internalist stance and the exchange interaction of quantum particles. We suggest that exchange interaction can also be viewed using ecological ideas related to apparatus-object. This can also help develop the important notion of complementarity in biosystems in relation to the nature and generation of information at the microphysical scale.     

Arrestin-mediated signaling: Is there a controversy?

The activation of the mitogen-activated protein(MAP) kinases extracellular signal-regulated kinase(ERK)1/2 was traditionally used as a readout of signaling of G protein-coupled receptors(GPCRs) via arrestins, as opposed to conventional GPCR signaling via G proteins. Several recent studies using HEK293 cells where all G proteins were genetically ablated or inactivated, or both non-visual arrestins were knocked out, demonstrated that ERK1/2 phosphorylation requires G protein activity, but does not necessarily require the presence of non-visual arrestins. This appears to contradict the prevailing paradigm. Here we discuss these results along with the recent data on gene edited cells and arrestinmediated signaling. We suggest that there is no real controversy. G proteins might be involved in the activation of the upstream-most MAP3Ks, although in vivo most MAP3K activation is independent of heterotrimeric G proteins, being initiated by receptor tyrosine kinases and/or integrins. As far as MAP kinases are concerned, the best-established role of arrestins is scaffolding of the three-tiered cascades(MAP3K-MAP2 K-MAPK). Thus, it seems likely that arrestins, GPCRbound and free, facilitate the propagation of signals in these cascades, whereas signal initiation via MAP3K activation may be independent of arrestins. Different MAP3Ks are activated by various inputs, some of which are mediated by G proteins, particularly in cell culture, where we artificially prevent signaling by receptor tyrosine kinases and integrins, thereby favoring GPCR-induced signaling. Thus, there is no reason to change the paradigm: Arrestins and G proteins play distinct non-overlapping roles in cell signaling.     

Is there evidence of learned helplessness in horses?

Learned helplessness is a psychological condition whereby individuals learn that they have no control over unpleasant or harmful conditions, that their actions are futile, and that they are helpless. In a series of experiments in which dogs were exposed to inescapable shocks, this lack of control subsequently interfered with the ability to learn an avoidance task. There is evidence that both neural adaptations and behavioral despair occur in response to uncontrollable aversive experiences in rodents, although this has yet to be demonstrated in other species such as horses. However, certain traditional methods of horse training and some behavioral modification techniques--it has been suggested--may involve aversive conditions over which the horse has little or no control. When training and management procedures are repeatedly unpleasant for the horse and there is no clear association between behavior and outcome, this is likely to interfere with learning and performance-in addition to compromising welfare. This article reviews published literature and anecdotal evidence to explore the possibility that the phenomenon, learned helplessness, occurs in the horse.