The claw closer muscle of Neohelice granulata (Grapsoidea, Varunidae): a morphological and histochemical study
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Longo, M.V., Goldemberg, A.L. and Díaz, A.O. 2011. The claw closer muscle of Neohelice granulata (Grapsoidea, Varunidae): a morphological and histochemical study. —Acta Zoologica (Stockholm) 92: 126–133. The claw closer muscle of Neohelice granulata was studied according to histological, histochemical, and morphometrical criteria. Adult male crabs in intermoult stage were collected from Mar Chiquita Lagoon (Buenos Aires, Argentina). Muscle fibers show evident striations and oval-elongated nuclei with loose chromatin. The loose connective tissue among muscle fibers consists of cells and fibers embedded in an amorphous substance. Muscle histochemistry reveals two slow fiber types: ‘A’ and ‘B’. Prevailing A fibers are larger, and they usually show, with respect to B type, a weaker reaction to whole techniques. Fibers with short (SS), intermediate (IS), and long sarcomeres (LS) appear in the claw closer muscle, being the LS fibers predominant. Concluding, the histochemical and morphometrical characteristics of the claw closer muscle fibers of N. granulata are indicative of slow fibers. The slow A type (low resistant to fatigue) prevails.Keywords:
Claw
Muscle fibre
Like the chelipeds, the claw closer muscles of the adult lobster are asymmetric (dimorphic). In the crusher claw the closer muscle is composed entirely of slow fibers, and in the cutter claw it has 65 to 75 percent fast fibers and 25 to 35 percent slow fibers. While claw placement in the adult is essentially random, it can be demonstrated in two ways that the muscle fiber properties are not genetically fixed: (i) if one claw is removed in the fourth and early fifth stages, the remaining closer muscle develops all slow muscle fibers, and (ii) if the animals are raised in smooth-bottomed containers, both claws can become cutter types, having closer muscles with more than 50 percent fast fibers. Thus, as in vertebrate skeletal muscle, the properties of lobster closer muscle fibers can be transformed by various experimental manipulations.
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Summary. 1. Histological studies have been made of the growth of the longissimus dorsi (LD) and semitendinosus (ST) muscles of eight Hereford and eight Friesian steers between the ages of 11 days and 24 months. 2. It was found that the average sarcomere lengths of the muscle fibres varied considerably from animal to animal and muscle to muscle, due to postural shortening during rigor. The lengths of the constituent filaments of actin and myosin were, however, constant within a narrow range (1.30 and 1.50 μ, respectively). Hence it is possible to define a standard sarcomere length for reference, as the length when the actin filaments from each half of the sarcomere just touch in the middle. This length is 2.60 μ, after correction for fixation. Cross‐sectional areas and diameters of fibres were then corrected accordingly. 3. After correction in this way, it was found that the internal diameters of the muscle fibres increased from about 15 μ at 1 month to about 45 μ at 24 months. For the first 12 months of growth the cross‐sectional areas of the fibres kept in step with the cross‐sectional area of the muscle, but after that time the former parameter increased more rapidly than the latter, so that fibres appeared to be lost from the muscle as it aged further. In the ST muscles, this loss amounted to about 40% at 24 months. 4. The collagen content of the muscles was higher at the calf stage than later. From 6 months onwards however this content remained nearly constant (0.43 and 0.77% of the wet weight, for LD and ST muscles, respectively). These changes were easily observable in the histological sections. 5. The elastin content, both by semiquantitative histological estimation and by an exact chemical method, was found to be very low in the LD muscles (about 3% of the total connective tissue content), but much higher in the ST muscles (about 37%). In other muscles of prime cuts, such as biceps femoris, the elastin content is, however, of the same order as in the LD, so that its contribution to the toughness of most cuts of meat is probably insignificant. 6. More detailed conclusions of the results are given at the end of the paper.
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Variation of the length of skeletal muscle fibers and sarcomere lengths were investigated in extensor digitorum longus (EDL) and soleus (SOL) muscles in mice (ICR) during postnatal growth in the range from 2 to 12 weeks after the birth. EDL and SOL were fixed in 2.5% gultaraldehyde contained Lock's solution at right angle position of articulatio genus and talocruralis. Single muscle fibers were dissected and lengths of fibers were measured under the dissecting microscope. For measuring sarcomere lengthes, laser diffraction technique was used. Following results were obtained; (1) the length of muscles and muscle fibers increased rapidly up to 8 and 5 weeks in EDL and SOL respectively; (2) relative muscle and fiber lengths at 12 weeks against 2 weeks were 1.72 and 1.30 in EDL, 1.60 and 1.32 in SOL; (3) sarcomere lengths at both ends of the fiber showed no significant change during growth; (4) on the other hand, sarcomere lengths at mid point showed maximum values at 8 and 5 weeks in EDL and SOL respectively. These observations suggest that the sarcomere are stretched especially at mid point when lengths of muscle fibers increase rapidly. It would be possible to consider that this changes of the sarcomere length during postnatal growth affect the contractile properties of muscles.
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In this experiment,120-day-old Xueshan chickens with body weights of 1.5-1.6 kg were taken as the material.The ultrastructural changes of sarcomere length,muscle fiber diameter and shear force value of pectoral muscle at 0.5 h,2.0 h,4.0 h,8.0 h and 24.0 h during postmortem aging under 4 ℃ were evaluated.Results showed that postmortem aging under 4 ℃ could significantly improve the tenderness of meat.The muscle fiber diameter of Xueshan chickens increased significantly at 2.0-4.0 h postmortem(P0.05) and reduced significantly at 4.0-8.0 h postmortem(P0.05).The sarcomere length values significantly reduced at 0.5-4.0 h postmortem and increased at 4.0-8.0 h postmortem(P0.05).The shear force significantly increased at 0.5-2.0 h(P0.05) and significantly decreased at 2.0-8.0 h postmortem(P0.05),then decreased slowly.During postmortem aging muscle fiber diameter and shear force increased with reduced sarcomere length level,while during resolution of rigor the results was the opposite.The changes of shear force value of Xueshan chickens were positively correlated with the sarcomere length and muscle fiber diameter.The results also demonstrated that aging process of Xueshan chicken completed at 8.0 h postmortem at 4 ℃ in general.
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Abstract Changes of architecture of adult rat gastrocnemius medialis muscle (GM) due to growth were studied in relation to length‐force characteristics. Myofilament lengths were unchanged, indicating constant sarcomere length‐force characteristics. Number of sarcomeres within fibers was unchanged as a consequence of growth, allowing persistence of differences between proximal and distal fibers in all age groups. Distal fiber length at muscle optimum length was shorter for the 14‐ than for the 10‐ and 16‐week age groups despite a lack of difference of number of sarcomeres. This is indicative of a shift of optimum fiber length with respect to muscle length to lengths higher than optimum length. Some evidence for the occurrence of distribution of fiber optimum lengths with respect to muscle optimum length was found in other age groups as well, albeit of a smaller magnitude. Muscle and aponeurosis length increased substantially with growth. Functional effects of increased aponeurosis lengths were increased contributions to muscle length changes by the aponeurosis, allowing smaller fiber contributions in older animals. Fiber angle increased approximately 5° with growth. Despite the differences of architecture indicated above, muscle length range between optimum length and active slack length was constant. This was probably caused by widening of this length range in the youngest age group by variations of architecture within the muscle. It is concluded that adaptation of aspects of muscle architecture is an important mechanism for adult muscle growth in rat GM. Of these aspects regulation of muscle length seems a dominant factor.
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The focal nature of the damage when muscle fibers are stretched during activation results from heterogeneity in sarcomere length that arises during the contraction. We tested the hypothesis that muscle fibers that are more susceptible to contraction-induced injury, old vs. young, demonstrate greater heterogeneity in sarcomere length and consequently greater injury. An apparatus has been developed that measures spatially averaged sarcomere lengths (diffraction patterns) at five discrete regions along the length of a single fiber segment and the forces developed during experiments. Single permeabilized fiber segments were obtained from soleus muscles of 6 and 28 month old male Wistar rats. Maximally activated single fibers were stretched through a 40% strain at 0.5 fiber lengths/sec. Diffraction patterns were obtained on relaxed and maximally activated fibers, before and after the stretch. The two-fold greater force deficit produced in fibers of old, 20% force deficit, compared with young, 10% force deficit, rats was attributable to mechanical weaknesses associated with increased heterogeniety in sarcomere length. After the stretch, 80% of muscle fibers from young rats had only a single region that lost its diffraction pattern. In contrast, 70% of the fiber segments from muscles of old rats lost diffraction patterns in three or more regions. In electron micrographs of regions that maintained diffraction patterns 4% of the sarcomeres were damaged, whereas in regions that lost the pattern 15% were damaged. Consequently, for whole fiber segments, the number of damaged sarcomeres ranged from 2% to 7% for young rats and from 4% to 15% for old rats. For both groups, force deficits corresponded reasonably well with the number of damaged sarcomeres. Supported by NIA: AG-06157.
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Myofibril
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Endomysium
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Texture (cosmology)
Cooked meat
Meat tenderness
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Lameness due to claw overgrowth remains one of the main welfare challenges in dairy goat farms. Although claw trimming is a crucial part of the solution, most times there is a delay in its implementation, with no perceived consequences. The goal of this cross-sectional study was to assess the correlation between the size and deformation of dairy goats claws with lameness score. The width and length of the claws of 38 adult dairy goats were taken and classified as deformed (DEF) or non-deformed (NO_DEF). Lameness was also scored in the majority of the animals assessed for claw deformation. Deformation of at least one claw was present in 34 animals (89% of the total sample). From the 34 goats with deformed claws, 33 presented at least one deformed rear claw and 18 presented at least one deformed front claw. From the 152 claws assessed 58% were deformed (n = 88), of which 19% (n = 29) were front claws and 39% were rear claws (n = 59). Increased width of the front claws was associated with increased likelihood of having deformation with odds of 1.24, and the increased length explained 16% of the variation in lameness scores. A positive relation between lameness score and the number of deformed claws was also shown. Overall, these results suggest that the size of dairy goats' claws influences the prevalence of deformation and lameness severity and that the number of deformed claws affects goats' gait. They also help to build the argument in favor of regular trimming in dairy goat farms.
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The aim of this study was to analyze the effects of ultrasound bath intensity, CaCl2 and sodium tripolyphosphate (STPP) concentration on the ultrastructure of longissimus muscle fiber from milk goats. The sarcomere length was measured by atomic force microscopy. According to the results of AFM images, the sarcomere length is longest when the conditions were an intensity of 100 W ultrasound bath (42.77% increment), a concentration of 300 mM CaCl2 injection (44.68% increment) or 90 mM STPP injection (19.41% increment). Apart from the sarcomere length, the study put forward a potential index (roughness) to represent tenderness of meat which was treated by ultrasound bath. Among different methods, ultrasound bath was chosen as the preferred tenderization method. SCANNING 38:545-553, 2016. © 2016 Wiley Periodicals, Inc.
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