Effects of Elevated H\u3csup\u3e+\u3c/sup\u3e And P\u3csub\u3ei\u3c/sub\u3e on The Contractile Mechanics of Skeletal Muscle Fibres From Young and Old Men: Implications for Muscle Fatigue in Humans

The present study aimed to identify the mechanisms responsible for the loss in muscle power and increased fatigability with ageing by integrating measures of whole‐muscle function with single fibre contractile mechanics. After adjusting for the 22% smaller muscle mass in old (73–89 years, n = 6) compared to young men (20–29 years, n = 6), isometric torque and power output of the knee extensors were, respectively, 38% and 53% lower with age. Fatigability was ∼2.7‐fold greater with age and strongly associated with reductions in the electrically‐evoked contractile properties. To test whether cross‐bridge mechanisms could explain age‐related decrements in knee extensor function, we exposed myofibres (n = 254) from the vastus lateralis to conditions mimicking quiescent muscle and fatiguing levels of acidosis (H+) (pH 6.2) and inorganic phosphate (Pi) (30 mm). The fatigue‐mimicking condition caused marked reductions in force, shortening velocity and power and inhibited the low‐ to high‐force state of the cross‐bridge cycle, confirming findings from non‐human studies that these ions act synergistically to impair cross‐bridge function. Other than severe age‐related atrophy of fast fibres (−55%), contractile function and the depressive effects of the fatigue‐mimicking condition did not differ in fibres from young and old men. The selective loss of fast myosin heavy chain II muscle was strongly associated with the age‐related decrease in isometric torque (r = 0.785) and power (r = 0.861). These data suggest that the age‐related loss in muscle strength and power are primarily determined by the atrophy of fast fibres, but the age‐related increased fatigability cannot be explained by an increased sensitivity of the cross‐bridge to H+ and Pi

Australasian Sequestrate Fungi 19: Hysterangium colossum sp. nov.

Hysterangium colossum sp. nov, with extraordinarily large basidiomata for the genus, is described from dry Eucalyptus woodlands in the Australian Capital Territory and southeastern New South Wales. It typically grows in confluent clusters and has a thick peridium often invaginated into the gleba

Animal-fungal interactions 2: First report of mycophagy by the Eastern European Hedgehog, Erinaceus concolor Martin, 1837 (Mammalia: Eulipotyphla: Erinaceidae)

Mycophagy (fungivory) performs numerous important ecosystem functions for fungi, plants, and animals. Fungi serve as food for diverse mammals, ranging from bears, Ursus spp., to shrews, Sorex spp. However, among the many mammals reported to eat fungi, hedgehogs and other insectivores have been poorly studied. Based on microscopic examination of a fecal sample collected from an Eastern European Hedgehog (Erinaceus concolor) near Ula-MuÄŸla, Turkey, we provide the first confirmed evidence of mycophagy by hedgehogs and review the literature on hedgehog mycophagy

Force-velocity-power and Force-pCa Relationships of Human Soleus Fibers After 17 Days of Bed Rest

Soleus muscle fibers from the rat display a reduction in peak power and Ca2+ sensitivity after hindlimb suspension. To examine human responses to non-weight bearing, we obtained soleus biopsies from eight adult men before and immediately after 17 days of bed rest (BR). Single chemically skinned fibers were mounted between a force transducer and a servo-controlled position motor and activated with maximal (isotonic properties) and/or submaximal (Ca2+ sensitivity) levels of free Ca2+. Gel electrophoresis indicated that all pre- and post-BR fibers expressed type I myosin heavy chain. Post-BR fibers obtained from one subject displayed increases in peak power and Ca2+ sensitivity. In contrast, post-BR fibers obtained from the seven remaining subjects showed an average 11% reduction in peak power (P \u3c 0.05), with each individual displaying a 7–27% reduction in this variable. Post-BR fibers from these subjects were smaller in diameter and produced 21% less force at the shortening velocity associated with peak power. However, the shortening velocity at peak power output was elevated 13% in the post-BR fibers, which partially compensated for their lower force. Post-BR fibers from these same seven subjects also displayed a reduced sensitivity to free Ca2+(P \u3c 0.05). These results indicate that the reduced functional capacity of human lower limb extensor muscles after BR may be in part caused by alterations in the cross-bridge mechanisms of contraction

Effect of 17 Days of Bed Rest on Peak Isometric Force and Unloaded Shortening Velocity of Human Soleus Fibers

The purpose of this study was to examine the effect of prolonged bed rest (BR) on the peak isometric force (Po) and unloaded shortening velocity (Vo) of single Ca2+-activated muscle fibers. Soleus muscle biopsies were obtained from eight adult males before and after 17 days of 6° head-down BR. Chemically permeabilized single fiber segments were mounted between a force transducer and position motor, activated with saturating levels of Ca2+, and subjected to slack length steps. Vo was determined by plotting the time for force redevelopment vs. the slack step distance. Gel electrophoresis revealed that 96% of the pre- and 87% of the post-BR fibers studied expressed only the slow type I myosin heavy chain isoform. Fibers with diameter \u3e100 μm made up only 14% of this post-BR type I population compared with 33% of the pre-BR type I population. Consequently, the post-BR type I fibers (n = 147) were, on average, 5% smaller in diameter than the pre-BR type I fibers (n = 218) and produced 13% less absolute Po. BR had no overall effect on Po per fiber cross-sectional area (Po/CSA), even though half of the subjects displayed a decline of 9–12% in Po/CSA after BR. Type I fiber Vo increased by an average of 34% with BR. Although the ratio of myosin light chain 3 to myosin light chain 2 also rose with BR, there was no correlation between this ratio and Vo for either the pre- or post-BR fibers. In separate fibers obtained from the original biopsies, quantitative electron microscopy revealed a 20–24% decrease in thin filament density, with no change in thick filament density. These results raise the possibility that alterations in the geometric relationships between thin and thick filaments may be at least partially responsible for the elevated Vo of the post-BR type I fibers

Turkish truffles 2: eight new records from Anatolia

Eight truffle taxa are identified as new records for Turkey: two representing Ascomycota (Tuber ferrugineum, Tuber puberulum) and six representing Basidiomycota (Hymenogaster rehsteineri, Hysterangium calcareum, Leucophleps aculeatispora, Melanogaster macrosporus, Sclerogaster compactus, Sclerogaster hysterangioides). We also report new localities within Turkey for Tuber borchii and Melanogaster ambiguus

Influence of acetaminophen and ibuprofen on in vivo patellar tendon adaptations to knee extensor resistance exercise in older adults

Millions of older individuals consume acetaminophen or ibuprofen daily and these same individuals are encouraged to participate in resistance training. Several in vitro studies suggest that cyclooxygenase-inhibiting drugs can alter tendon metabolism and may influence adaptations to resistance training. Thirty-six individuals were randomly assigned to a placebo (67 ± 2 yr old), acetaminophen (64 ± 1 yr old; 4,000 mg/day), or ibuprofen (64 ± 1 yr old; 1,200 mg/day) group in a double-blind manner and completed 12 wk of knee extensor resistance training. Before and after training in vivo patellar tendon properties were assessed with MRI [cross-sectional area (CSA) and signal intensity] and ultrasonography of patellar tendon deformation coupled with force measurements to obtain stiffness, modulus, stress, and strain. Mean patellar tendon CSA was unchanged (P > 0.05) with training in the placebo group, and this response was not influenced with ibuprofen consumption. Mean tendon CSA increased with training in the acetaminophen group (3%, P < 0.05), primarily due to increases in the mid (7%, P < 0.05) and distal (8%, P < 0.05) tendon regions. Correspondingly, tendon signal intensity increased with training in the acetaminophen group at the mid (13%, P < 0.05) and distal (15%, P = 0.07) regions. When normalized to pretraining force levels, patellar tendon deformation and strain decreased 11% (P < 0.05) and stiffness, modulus, and stress were unchanged (P > 0.05) with training in the placebo group. These responses were generally uninfluenced by ibuprofen consumption. In the acetaminophen group, tendon deformation and strain increased 20% (P < 0.05) and stiffness (−17%, P < 0.05) and modulus (−20%, P < 0.05) decreased with training. These data suggest that 3 mo of knee extensor resistance training in older adults induces modest changes in the mechanical properties of the patellar tendon. Over-the-counter doses of acetaminophen, but not ibuprofen, have a strong influence on tendon mechanical and material property adaptations to resistance training. These findings add to a growing body of evidence that acetaminophen has profound effects on peripheral tissues in humans

Australasian sequestrate fungi 18: Solioccasus polychromus gen. & sp. nov., a richly colored, tropical to subtropical, hypogeous fungus

Solioccasus polychromus gen. & sp. nov., the most brightly colored hypogeous fungus known, is described from Papua New Guinea and tropical northern Australia south into subtropical forests along the Queensland coast and coastal mountains to near Brisbane. Phylogenetic analysis of molecular data places it as a sister genus to Bothia in the Boletineae, a clade of predominantly ectomycorrhizal boletes. Ectomycorrhizal trees, such as members of the Myrtaceae (Eucalyptus, Corymbia, Lophostemon, Melaleuca spp.) and Allocasuarina littoralis, were present usually in mixture or in some cases dominant, so we infer some or all of them to be among the ectomycorrhizal hosts of S. polychromus.Cover image—Solioccasus polychromus, an Australasian, tropical to subtropical, hypogeous member of the Boletineae. Upper image by Roy Halling, immature specimens, lower image by Michael Castellano, mature specimens. See article by Trappe et al. in this issue.Keywords: ITS, Boletineae, ectomycorrhizae, rhizomorphs, Bothia, Boletales, Basidiomycota, LSU, tef1, DNA, EF1-α

Integrated Resistance and Aerobic Training Study - Sprint

Space flight causes reductions in fitness/health: (1) Cardiovascular -- reduced VO2max, cardiac output (2) Bone -- reduced bone mineral density (3) Muscle -- reduced mass, strength and endurance. Exercise is the primary countermeasure to protect against these changes and was made operational before completely mature. Research continues to identify most effective/efficient exercise programs. Crew medical tests (cardio, muscle, bone) do not yield sufficient information to fine tune the effectiveness of exercise programs, thus there is a need for more detailed testing aimed at identifying the most effective training program. The objective of this program was to obtain detailed information about crew physical fitness pre-and post-flight and evaluate new evidence based exercise prescription with higher intensity, lower duration and frequency