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1.
Distinct effects of climate warming on populations of silver fir (Abies alba) across Europe 下载免费PDF全文
2.
Body wall organization in enchytraeids 总被引:2,自引:2,他引:0
Roberto Valvassori Magda de Eguileor Giulio Lanzavecchia Giorgio Scari 《Hydrobiologia》1989,180(1):83-89
The muscle organization of the body wall in some species of oligochaetes belonging to the Enchytraeus genus is described. No differences have been detected in their circular muscles, whereas longitudinal muscles show significant differences, allowing an easy identification of the various worm species. In particular, differences are noticeable in the external longitudinal layer. These observations suggest that structural and ultrastructural muscle fiber organizations can be used as a taxonomic tool. 相似文献
3.
Tatsumi Nagahama Mitsuru Takata 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1990,167(1):1-10
1. | Spikes in Aplysia MA1 neurons produced excitatory (EJPs), inhibitory (IJPs), and diphasic inhibitory-excitatory junction potentials in different fibers of the buccal muscles. |
2. | The IJPs following the MA1 spikes were recorded in the muscle fibers innervated by the jaw-closing motoneurons. The depolarization of muscle fibers produced by the motoneurons was largely suppressed by simultaneous MA1 firing, suggesting that the MA1 neurons make a direct connection to a part of the muscle fibers innervated by these motoneurons and inhibit them. |
3. | The excitatory and inhibitory components of the junction potentials produced by MA1 were reversibly blocked by hexamethonium and d-tubocurarine, respectively. In contrast, the EJPs produced by the jaw-closing motoneurons were blocked by an amino acid antagonist, suggesting that the MA1 neurons and the jaw-closing motoneurons use different transmitters in the nerve-muscle junctions. |
4. | The jaw movement produced by the jaw-closing motoneurons was suppressed by simultaneous MA1 firing, and the suppression was released by d-tubocurarine, suggesting that the IJPs produced by MA1 may contribute to the suppression of jaw movement. The firing of MA1 produced the vertical movement of the buccal muscles, which was blocked by hexamethonium, suggesting that the EJPs produced by MA1 may contribute to the vertical movement. |
4.
The longitudinal anthropological age changes in a sample of coastal fishermen in West Bengal are discussed. The results show
that some traits follow the trends observed in ageing of Western populations, for instance nasal length and breadth continue
to increase throughout life in both sexes. Stature follows also the trend generally observed: a decrease occurs indeed from
35 years of age in both sexes, the decline is becoming higher with increasing age. The typical ecological conditions of our
population influence the rate of change in other traits, such as weight and biacromial diameter. Weight is known to be influenced
by the nutritional status and the way of life. It explains that in our study of males an early increase of weight and biacromial
diameter is observed first and a decrease afterwards. In females, however, a decrease is observed already from 35 years of
age. This kind of analysis was only possible with the help of longitudinal data and in a well defined population: only longitudinal
data is free from the effect of secular changes and of selective death. 相似文献
5.
Masayuki Nishida Hirotaka Nishijima Kazuya Yonezawa Isao Sato Teisuke Anzai Kohichi Okita Hisakazu Yasuda 《European journal of applied physiology and occupational physiology》1992,64(6):528-533
To assess exercise energy metabolism of forearm flexor muscles in rowers, six male student rowers and six control subjects matched for age and sex were studied using phosphorus-31 magnetic resonance spectroscopy (31P-MRS). Firstly, to adjust for the effect of differences in cross-sectional muscle area, the maximal cross-sectional area (CSAmax) of the forearm flexor muscles was estimated in each individual using magnetic resonance imaging. Multistage exercise was then carried out with an initial energy production of 1 J.cm-2 CSAmax for 1 min and an increment of 1 J.cm-2 CSAmax every minute to the point of muscle exhaustion. A series of measurements of 31P-MRS were performed every minute. The CSAmax was significantly greater in the student rowers than in the control subjects [19.8 (SD 2.2) vs 17.1 (SD 1.2) cm2, P less than 0.05]. The absolute maximal exercise intensity (J.min-1) was greater in the rowers than in the control subjects. However, the maximal exercise intensity per unit of muscle cross sectional area (J.min-1.cm-2) was not significantly different between the two groups. During mild to moderate exercise intensities, a decrease in phosphocreatine and an increase in inorganic phosphate before the onset of acidosis were significantly less in the rowers, indicating a requirement of less adenosine 5'-diphosphate to drive adenosine 5'-triphosphate production. The onset of acidosis was also significantly delayed in the rowers. No difference was observed in forearm blood flow between the two groups at the same exercise intensity (J.min-1.cm-2).(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
6.
Darryl J. Lee Maria J. Stokes Robert J. Taylor Robert G. Cooper 《European journal of applied physiology and occupational physiology》1992,64(3):199-203
In 31 normal subjects (17 male), aged 19-48 years, and 8 patients with chronic low back pain (4 male), aged 37-55 years, the repeatability of surface recordings of acoustic myography (AMG) and electromyography (EMG) were examined in the lumbar paraspinal muscles. Five isometric test positions were examined. In 21 of the normal subjects, four positions tested were: quiet standing, half extension from prone lying, full extension from prone with and without resistance. In 10 of the normal subjects and the 8 back pain patients, a standardised, unsupported horizontal position with the upper body over the end of a couch was tested. The AMG and EMG signals were full-wave rectified and integrated (iAMG and iEMG). The variability of recordings during repeated 5-s isometric contractions was assessed by analysis of variance (ANOVA) and the coefficient of variation (CV) was calculated from the ANOVA. Both recording techniques produced the most repeatable results during the unsupported, horizontal hold position. In the normal subjects, CV were, iAMG 5.6%, iEMG 4.9%; and in the patients, iAMG 4.4%, iEMG 2.6%. The CV for the other four isometric test positions ranged from 15.3% to 29.4% for iAMG, and 8% to 15.7% for iEMG. These results demonstrated that a controlled test manoeuvre for examining AMG and EMG of the paraspinal muscles was vital for repeatable recordings. The CV for the standardised, horizontal position were lower than for previously published results.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
7.
The relative appearance of the parietal muscles in the development of the zooids has been studied in several ctenostomatous and “cheilostomatous” species. A comparison of the different on-togenetical sequences demonstrated that a “cheilostomatous” type of organization of the zooids with a great probability has been achieved in minimum three times independentl and originated from different ctenostomatous sub-grous: the Membranidea from plesiomorgic victorelloids (ancestors of Bulbella with not yet developed peristomial tube), the Inoviceiata (Aetea) from advanced forms of victorelloids with reduced primary parietal muscles (perhaps stcies related to Pottsiella), and Penetrantia from arachnidioid or vesicularioid ancestors (?). Therefore, the classical orders α“Ctenostomata” and “Cheilostomata” represent only “stage groups” but no monohyletic systematical units. Because of the new concept and interpretation I propose a new name for the united group: Cteno-Cheilostomata, supra-ord. nov. 相似文献
8.
Interactions between intrinsic regulation and neural modulation of acetylcholinesterase in fast and slow skeletal muscles 总被引:2,自引:0,他引:2
Janez Sketelj Neva Črne-Finderle Samo Ribarič Miro Brzin 《Cellular and molecular neurobiology》1991,11(1):35-54
1. Initiation of subsynaptic sarcolemmal specialization and expression of different molecular forms of AChE were studied in fast extensor digitorum longus (EDL) and slow soleus (SOL) muscle of the rat under different experimental conditions in order to understand better the interplay of neural influences with intrinsic regulatory mechanisms of muscle cells. 2. Former junctional sarcolemma still accumulated AChE and continued to differentiate morphologically for at least 3 weeks after early postnatal denervation of EDL and SOL muscles. In noninnervated regenerating muscles, postsynaptic-like sarcolemmal specializations with AChE appeared (a) in the former junctional region, possibly induced by a substance in the former junctional basal lamina, and (b) in circumscribed areas along the whole length of myotubes. Therefore, the muscle cells seem to be able to produce a postsynaptic organization guiding substance, located in the basal lamina. The nerve may enhance the production or accumulation of this substance at the site of the future motor end plate. 3. Significant differences in the patterns of AChE molecular forms in EDL and SOL muscles arise between day 4 and day 10 after birth. The developmental process of downregulation of the asymmetric AChE forms, eliminating them extrajunctionally in the EDL, is less efficient in the SOL. The presence of these AChE forms in the extrajunctional regions of the SOL correlates with the ability to accumulate AChE in myotendinous junctions. The typical distribution of the asymmetric AChE forms in the EDL and SOL is maintained for at least 3 weeks after muscle denervation. 4. Different patterns of AChE molecular forms were observed in noninnervated EDL and SOL muscles regenerating in situ. In innervated regenerates, patterns of AChE molecular forms typical for mature muscles were instituted during the first week after reinnervation. 5. These results are consistent with the hypothesis that intrinsic differences between slow and fast muscle fibers, concerning the response of their AChE regulating mechanism to neural influences, may contribute to different AChE expression in fast and slow muscles, in addition to the influence of different stimulation patterns. 相似文献
9.
Most previously published electromyographic (EMG) studies have indicated that the temporalis muscles in humans become almost
electrically quiet during incisai biting. These data have led various workers to conclude that these muscles may contribute
little to the incisai bite force. The feeding behavior and comparative anatomy of the incisors and temporalis muscles of certain
catarrhine primates, however, suggest that the temporalis muscle is an important and powerful contributor to the bite force
during incision. One purpose of this study is to analyze the EMG activity of the masseter and temporalis muscles in both humans
and macaques with the intention of focusing on the conflict between published EMG data on humans and inferences of muscle
function based on the comparative anatomy and behavior of catarrhine primates. The EMG data collected from humans in the present
study indicate that, in five of seven subjects, the masseter,anterior temporalis, and posterior temporalis muscles are very active during apple incision (i.e., relative to EMG activity
levels during apple and almond mastication). In the other two human subjects the EMG levels of these muscles are lower during
incision than during mastication, but in no instance are these muscles ever close to becoming electrically quiet. The EMG
data on macaques indicate that, in all six subjects, the masseter, anterior temporalis, and posterior temporalis muscles are
very active during incision. These data are in general agreement with inferences on muscle function that have been drawn from
the comparative anatomy and behavior of primates, but they do not agree with previous experimental data. The reason for this
disagreement is probably due to differences in the experimental procedure. In previous studies subjects simply bit isometrically
on their incisors and the resulting EMG pattern was compared to the pattern associated with powerful clenching in centric
occlusion. In the present study the subjects incised into actual food objects, and the resulting EMG pattern was compared
to the pattern associated with mastication of various foods. It is not surprising that these two procedures result in markedly
different EMG patterns, which in turn result in markedly different interpretations of jaw-muscle function. In an attempt to
explain the evolution of the postorbital septum in anthropoids, it has been suggested that the anterior temporalis is more
active than the masseter during incision (Cachel, 1979). The human and macaque EMG data do not support this hypothesis; during
incision, the two muscles show no consistent differences in humans and the masseter appears to be in fact more active than
the anterior temporalis in macaques. 相似文献
10.
Summary Distribution of glycogen particles in semithin and ultrathin sections of biopsy samples from human muscles subjected to either short- or long-term running were investigated using PAS and Periodic Acid-ThioSemiCarbazide-Silver Proteinate (PA-TSC-SP) staining methods. Glycogen particles were predominantly found immediately under the sarcolemma or aligned along the myofibrillar Iband. After long-term exhaustive exercise type-1 fibers with a few or no glycogen particles in the core of the fibers were frequently observed. The subsarcolemmal glycogen stores of these depleted type-1 fibers were about three times as large as after exhaustive short-time exercise. Another indication of utilization of subsarcolemmal glycogen stores during anaerobic exercise was that many particles displayed a pale, rudimentary shape. This observation suggests fragmental metabolization of glycogen. Thus, depending on type of exercise and type of fiber differential and sequential glycogen utilization patterns can be observed. 相似文献