Decoupling of muscle-tendon unit and fascicle velocity contributes to the in vivo stretch-shortening cycle effect in the male human triceps surae muscle.

During the shortening of stretch-shortening cycles (SSCs), muscle force output is enhanced compared with pure shortening (SHO), referred to as the SSC-effect. In general, muscle-tendon unit (MTU), muscle belly, muscle fascicle, and tendon length changes can be decoupled during contraction, which affects force generation and elastic recoil. We researched whether MTU decoupling contributes to the SSC-effect.

Age and mating status have complex but modest effects on the critical thermal limits of adult Mediterranean fruit flies from geographically divergent populations.

The highly invasive Mediterranean fruit fly (medfly), Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), is currently expanding its geographic distribution into cooler temperate areas of the Northern Hemisphere. In marginal conditions, the invasion potential of medfly depends in part on innate tolerance to the novel environmental conditions. Physiological tolerances are potentially influenced by interactions among multiple factors, such as organism age or reproductive maturity, sex, and mating status.

Force re-development after shortening reveals a role for titin in stretch-shortening performance enhancement in skinned muscle fibres.

Stretch-shortening cycles (SSCs) involve muscle lengthening (eccentric contractions) instantly followed by shortening (concentric contractions). This combination enhances force, work and power output compared with pure shortening contractions, which is known as the SSC effect. Recent evidence indicates both cross-bridge (XB)-based and non-XB-based (e.

Gauging force by tapping tendons? Inaccurately in the human patellar tendon.

Accurately estimating in vivo tendon load non-invasively remains a major challenge in biomechanics, which might be overcome by shear-wave tensiometry. Shear-wave tensiometry measures the speed of mechanically induced tendon shear waves by skin-mounted accelerometers. To gauge the feasibility and accuracy of this novel technique, we obtained patellar tendon shear wave speeds via shear-wave tensiometry during sustained or ramp voluntary contractions of the knee extensors in two experiments (n = 8 in both).

Regulation of the DLC3 tumor suppressor by a novel phosphoswitch.

Deleted in liver cancer 3 (DLC3) is a Rho GTPase-activating protein (RhoGAP) that plays a crucial role in maintaining adherens junction integrity and coordinating polarized vesicle transport by modulating Rho activity at the plasma membrane and endomembranes. By employing bioinformatical sequence analysis, experiments, and assays we here identified a polybasic region (PBR) in DLC3 that facilitates the association of the protein with cellular membranes. Within the PBR, we mapped two serines whose phosphorylation can alter the electrostatic character of the region.

Unlocking the benefit of active stretch: the eccentric muscle action, not the preload, maximizes muscle-tendon unit stretch-shortening cycle performance.

Stretch-shortening cycles (SSCs) outperform shortening contractions preceded by isometric contractions in terms of enhanced force/torque, work, and power production during shortening. This so-called SSC effect is presumably related to the active muscle stretch before shortening in SSCs. However, it remains unclear whether the effects of stretch-induced higher preload level or stretch-induced history dependence maximize the SSC effect.

Gamma-Irradiated Female Aedes aegypti Mosquitoes Exhibit Greater Susceptibility to Mayaro Virus.

Mayaro virus (MAYV) is an alphavirus endemic in many parts of Central and South America transmitted to humans by Aedes aegypti. Currently, there is no vaccine or treatment of Mayaro infection, and therefore it is essential to control transmission by reducing populations of Ae. aegypti.

Bigger isn't always better: Challenging assumptions about the associations between diapause, body weight, and overwintering survival.

During the winter, animals face limited food availability. Many animals enter dormancy to reduce their winter energy expenditure. Most insects spend the winter in diapause, a state of programmed dormancy.

Seasonality of forest insects: why diapause matters.

Insects have major impacts on forest ecosystems, from herbivory and soil-nutrient cycling to killing trees at a large scale. Forest insects from temperate, tropical, and subtropical regions have evolved strategies to respond to seasonality; for example, by entering diapause, to mitigate adversity and to synchronize lifecycles with favorable periods. Here, we show that distinct functional groups of forest insects; that is, canopy dwellers, trunk-associated species, and soil/litter-inhabiting insects, express a variety of diapause strategies, but do not show systematic differences in diapause strategy depending on functional group.

Eccentric exercise ≠ eccentric contraction.

Whether eccentric exercise involves active fascicle stretch is unclear due to muscle-tendon unit (MTU) series compliance. Therefore, this study investigated the impact of changing the activation timing and level (i.e.

Residual force depression is not related to positive muscle fascicle work during submaximal voluntary dorsiflexion contractions in humans.

Residual force depression (rFD) following active muscle shortening is assumed to correlate most strongly with muscle work, but this has not been tested during voluntary contractions in humans. Using dynamometry, we compared steady-state ankle joint torques (N = 16) following tibialis anterior (TA) muscle-tendon unit (MTU) lengthening and shortening to the time-matched torque during submaximal voluntary fixed-end dorsiflexion reference contractions (REF) at a matched MTU length and EMG amplitude. Ultrasound revealed significantly reduced (P < 0.

The force-length relation of the young adult human tibialis anterior.

Background: Knowledge of the muscle's lengths at which maximum active isometric force is attained is important for predicting forces during movement. However, there is limited information about the force-length properties of a human muscle that plays crucial roles during locomotion; the tibialis anterior (TA). We therefore aimed to estimate TA's force-length relation from dorsiflexor torque-angle curves constructed from eight women and eight men.

Developing methods for chilling, compacting, and sterilizing adult Aedes aegypti (Diptera: Culicidae) and comparing mating competitiveness between males sterilized as adults versus pupae for sterile male release.

The yellow fever mosquito, Aedes aegypti L., can transmit several pathogens responsible for human diseases. With insecticide resistance development becoming a concern, alternative control strategies are needed for Ae.

Simulated climate warming causes asymmetric responses in insect life-history timing potentially disrupting a classic ecological speciation system.

Climate change may alter phenology within populations with cascading consequences for community interactions and on-going evolutionary processes. Here, we measured the response to climate warming in two sympatric, recently diverged (~170 years) populations of Rhagoletis pomonella flies specialized on different host fruits (hawthorn and apple) and their parasitoid wasp communities. We tested whether warmer temperatures affect dormancy regulation and its consequences for synchrony across trophic levels and temporal isolation between divergent populations.

Sequence and expression analysis of the spermatogenesis-specific gene cognates, wampa and Prosα6T, in Drosophila suzukii.

The sterile insect technique (SIT) is a highly effective biologically-based method for the population suppression of highly invasive insect pests of medical and agricultural importance. The efficacy of SIT could be significantly enhanced, however, by improved methods of male sterilization that avoid the fitness costs of irradiation. An alternative sterilization method is possible by gene-editing that targets genes essential for sperm maturation and motility, rendering them nonfunctional, similar to the CRISPR-Cas9 targeting of β2-tubulin in the genetic model system, Drosophila melanogaster.

Divergence in cell cycle progression is associated with shifted phenology in a multivoltine moth: the European corn borer, Ostrinia nubilalis.

Evolutionary change in diapause timing can be an adaptive response to changing seasonality, and even result in ecological speciation. However, the molecular and cellular mechanisms regulating shifts in diapause timing remain poorly understood. One of the hallmarks of diapause is a massive slowdown in the cell cycle of target organs such as the brain and primordial imaginal structures, and resumption of cell cycle proliferation is an indication of diapause termination and resumption of development.

Tendon compliance and preload must be considered when determining the in vivo force-velocity relationship from the torque-angular velocity relation.

In vivo, the force-velocity relation (F-v-r) is typically derived from the torque-angular velocity relation (T-ω-r), which is subject to two factors that may influence resulting measurements: tendon compliance and preload prior to contraction. The in vivo plantar flexors' T-ω-r was determined during preloaded maximum voluntary shortening contractions at 0-200°/s. Additionally, we used a two factor block simulation study design to independently analyze the effects of preload and tendon compliance on the resulting T-ω-r.

The history-dependent features of muscle force production: A challenge to the cross-bridge theory and their functional implications.

The cross-bridge theory predicts that muscle force is determined by muscle length and the velocity of active muscle length changes. However, before the formulation of the cross-bridge theory, it had been observed that the isometric force at a given muscle length is enhanced or depressed depending on active muscle length changes before that given length is reached. These enhanced and depressed force states are termed residual force enhancement (rFE) and residual force depression (rFD), respectively, and together they are known as the history-dependent features of muscle force production.

Cold tolerance and diapause within and across trophic levels: Endoparasitic wasps and their fly host have similar phenotypes.

Low temperatures associated with winter can limit the survival of organisms, especially ectotherms whose body temperature is similar to their environment. However, there is a gap in understanding how overwintering may vary among groups of species that interact closely, such as multiple parasitoid species that attack the same host insect. Here, we investigate cold tolerance and diapause phenotypes in three endoparasitoid wasps of the apple maggot fly Rhagoletis pomonella (Diptera: Tephritidae): Utetes canaliculatus, Diachasma alloeum, and Diachasmimorpha mellea (Hymenoptera: Braconidae).