RESUMEN
Physical contact is prevalent in the animal kingdom to recognize suitable mates by decoding information about sex, species, and maturity. Although chemical cues for mate recognition have been extensively studied, the role of mechanical cues remains elusive. Here, we show that C. elegans males recognize conspecific and reproductive mates through short-range cues, and that the attractiveness of potential mates depends on the sex and developmental stages of the hypodermis. We find that a particular group of cuticular collagens is required for mate attractiveness. These collagens maintain body stiffness to sustain mate attractiveness but do not affect the surface properties that evoke the initial step of mate recognition, suggesting that males utilize multiple sensory mechanisms to recognize suitable mates. Manipulations of body stiffness via physical interventions, chemical treatments, and 3D-printed bionic worms indicate that body stiffness is a mechanical property for mate recognition and increases mating efficiency. Our study thus extends the repertoire of sensory cues of mate recognition in C. elegans and provides a paradigm to study the important roles of mechanosensory cues in social behaviors.
Asunto(s)
Caenorhabditis elegans , Conducta Sexual Animal , Animales , Masculino , Caenorhabditis elegans/fisiología , Conducta Sexual Animal/fisiología , Sensación , Reproducción , Reconocimiento en PsicologíaRESUMEN
To study the influence mechanism of gangue backfilling material (GBM) with different particle sizes on overburden deformation, the particle movement characteristics and the mechanism of stiffness difference with different particle sizes of GBM were analysed by physical compression and particle flow numerical simulations. Then, combined with a similar material simulation method, the deformation characteristics of roof overburden and the evolution process of floor stress in backfill mining with backfilling bodies of different stiffness levels were studied. The results indicate that the subsidence decreased monotonously with a decrease in the particle size, and the stiffness of the GBM increased significantly under the same vertical load. The small-particle gangue moved downward in the layered law under the same load conditions, while the large-particle gangue moved downward through rotation, rubbing, crushing, and filling interaction processes. In the treatment of goaf by the backfilling method, the entire process of overlying strata movement mainly experienced bending, micro-fracture, separation, compaction, and new fracture, and the anti-deformation capacity of the backfilling body directly determined the deformation and movement of the overburden strata in a goaf. In the backfilling method, the greater the stiffness of the filling body, the smaller the advanced support pressure, and the more effective it was to inhibit pressure relief from the floor.
Asunto(s)
Minas de Carbón , Minas de Carbón/métodos , Simulación por Computador , Presión , Tamaño de la PartículaRESUMEN
BACKGROUND: The current evidence leaves certain questions unanswered, including whether well-trained athletes adapt to different slope gradients in the same way as amateurs, and whether stiffness influences spatiotemporal adaptations during uphill running. RESEARCH QUESTION: This study aimed to determine the effect of different slope gradients (0%-11%) on spatiotemporal gait characteristics during running, taking into account the influence of athletic level, vertical and leg stiffness. METHODS: Male endurance runners (12 amateurs, 10 highly-trained) performed a running test on a motorized treadmill. The running velocity was set at 12 km/h, and participants completed six different running conditions (0, 3, 5, 7, 9 and 11% gradients). Spatiotemporal parameters were measured using the OptoGait system. Vertical (Kvert) and leg (Kleg) stiffness were calculated according to the sine-wave method. RESULTS: A 2 (amateur; highly-trained) × 6 (running conditions) ANOVA found no significant between-group differences in spatiotemporal parameters at any gradient (P ≥ 0.05); however, significant Kvert and Kleg differences (P < 0.05) were found within both groups with increasing gradients. Stepwise linear regression analysis showed that Kleg was strongly associated with contact time (R2 = 0.797, P < 0.001), whereas Kvert was associated with spatiotemporal adaptations to different slope gradients (R2 = 0.547, P = 0.002). SIGNIFICANCE: An increased slope gradient (0-11%) at a given running velocity (12 km.h-1) caused spatiotemporal adaptations (i.e., increased CT and SF and decreased FT, SL and SA) regardless of the athletic level of the runner, although a non-significant trend differentiated the adaptations between the amateur and highly-trained groups. The results also indicated that leg stiffness plays a key role in the characteristics of spatiotemporal gait during level running, whereas vertical stiffness is strongly associated with spatiotemporal adaptations when running uphill.
Asunto(s)
Adaptación Fisiológica , Atletas , Orientación Espacial/fisiología , Carrera/fisiología , Adulto , Prueba de Esfuerzo , Marcha/fisiología , Humanos , Masculino , Músculo Esquelético/fisiología , Navegación Espacial/fisiologíaRESUMEN
Whole-body stiffness in fishes has important consequences for swimming mode, speed and efficiency, but the contribution of vertebral column stiffness to whole-body stiffness is unclear. In our opinion, this lack of clarity is due in part to the lack of studies that have measured both in vitro mechanical properties of the vertebral column as well as in vivo vertebral kinematics in the same species. Some lack of clarity may also come from real variation in the mechanical role of the vertebral column across species. Previous studies, based on either mechanics or kinematics alone, suggest species-specific variation in vertebral column locomotor function that ranges from highly stiff regimes that contribute greatly to whole-body stiffness, and potentially act as a spring, to highly compliant regimes that only prohibit excessive flexion of the intervertebral joints. We review data collected in combined investigations of both mechanics and kinematics of three species, Myxine glutinosa, Acipenser transmontanus, and Morone saxatilis, to illustrate how mechanical testing within the context of the in vivo kinematics more clearly distinguishes the role of the vertebral column in each species. In addition, we identify species for which kinematic data are available, but mechanical data are lacking. We encourage further investigation of these species to fill these mechanical data gaps. Finally, we hope these future combined analyses will identify certain morphological, mechanical, or kinematic parameters that might be associated with certain vertebral column functional regimes with respect to body stiffness.