Rapid shell closure in the brachiopods Terebratulina retusa and Terebrataua transversa

1992 ◽  
Vol 72 (3) ◽  
pp. 579-598 ◽  
Author(s):  
Spafford C. Ackerly
Keyword(s):  
Detailed Analysis ◽  
Hydrodynamic Model ◽  
Puget Sound ◽  
Muscle Length ◽  
Adductor Muscle ◽  
Muscle Physiology ◽  
Shell Closure ◽  
Functional Architecture ◽  
Adductor Muscles ◽  
Kinematic Properties

Rapid shell closure in articulate brachiopods, occurring by a twitch contraction of the the ‘quick’ adductor muscles, is a response to disturbance or to physiological requirements of the organism. The relative simplicity of the closing system permits a detailed analysis of the functional architecture of the mechanism and the underlying principles of skeleto-muscular organization, in terms of (1) basic kinematic properties of the system (speeds and times of closure), (2) hydrodynamic reactions resisting closure, and (3) considerations of muscle physiology and mechanics.Analyses of shell closure in the brachiopods Terebratulina retusa from the Firth of Lorn, Scotland, and Terebratalia transversa from Puget Sound, USA, reveal (1) shell-closing times of the order of 50 to 70 ms, (2) closing velocities of the order of 3·5 radians s-1, from initial gapes of about 0·05 to 0·2 rad, and (3) muscle moment forces and hydrodynamic reactions with magnitudes of the order of 5 × 10-4 N m (5 g cm). Muscle tensions developed in the ‘quick’ adductor muscle are of the order of 105 N m2, and contraction velocities are of the order of one muscle length per second. Hydrodynamic reactions are a fundamental constraint on the closing mechanism, as determined by the concordance of actual closing events with predictions of a hydrodynamic model.

scholarly journals On the Origins of Phonology

2017 ◽  
Vol 26 (2) ◽  
pp. 132-139 ◽  
Author(s):  
Iris Berent
Keyword(s):  
Detailed Analysis ◽  
Language Disorders ◽  
The Other ◽  
Sensorimotor System ◽  
Speech And Language ◽  
Functional Architecture ◽  
Phonological Knowledge ◽  
The One ◽  
Speech And Language Disorders ◽  
Phonological System

Why do humans drink and drive but fail to rdink and rdive? Here, I suggest that these regularities could reflect abstract phonological principles that are active in the minds and brains of all speakers. In support of this hypothesis, I show that (a) people converge on the same phonological preferences (e.g., dra over rda) even when the relevant structures (e.g., dra, rda) are unattested in their language and that (b) such behavior is inexplicable by purely sensorimotor pressures or experience with similar syllables. Further support for the distinction between phonology and the sensorimotor system is presented by their dissociation in dyslexia, on the one hand, and the transfer of phonological knowledge from speech to sign, on the other. A detailed analysis of the phonological system can elucidate the functional architecture of the typical mind/brain and the etiology of speech and language disorders.

scholarly journals Ultrastructure of phagocytes and oocysts of Nematopsis sp. (Apicomplexa, Porosporidae) infecting Crassostrea rhizophorae in Northeastern Brazil

2019 ◽  
Vol 28 (1) ◽  
pp. 97-104
Author(s):  
Themis Jesus Silva ◽  
Emerson Carlos Soares ◽  
Graça Casal ◽  
Sónia Rocha ◽  
Elton Lima Santos ◽  
...  
Keyword(s):  
Parasitophorous Vacuole ◽  
Adductor Muscle ◽  
Systematic Position ◽  
Variable Number ◽  
Northeastern Brazil ◽  
Ultrastructural Organization ◽  
Oocyst Wall ◽  
Transmission Electron ◽  
Adductor Muscles ◽  
Crassostrea Rhizophorae

Abstract This work describes the detailed ultrastructural morphology of the phagocyte imprisoning an oyster of Nematopsis (Apicomplexa) found in Crassostrea rhizophorae, in the city of Maceió (AL), Brazil. The highly infected hosts had half-open leaflets with weak, slow retraction of the adductor muscles. Variable number of ellipsoid oocytes, either isolated and or clustered, was found between myofibrils of the adductor muscle. Each oocyst was incarcerated in a parasitophorous vacuole of host uninucleated phagocyte. The oocysts were composed of a dense wall containing a uninucleate vermiform sporozoite. The wall of the fine oocysts was composed of homogeneous electron-lucent material formed by three layers of equal thickness, having a circular orifice-micropyle obstructed by the operculum. The oocysts presented ellipsoid morphology with their wall was surrounded by a complex network of numerous microfibrils. Important details of the taxonomic value were visualized such as the ultrastructural organization of the oocyst wall and the organization of the micropyle and operculum, beyond the microfibrils that protrude from the oocyst wall only observed by transmission electron microscopy (TEM) and that may aid in the identification of the species. However, in order to clarify the systematic position of the species reported of the genus Nematopsis, it is important to proceed with genetic analyses.

The mechanism of boring in Zirphaea crispata (L.) (Bivalvia: Pholadidae)

1968 ◽  
Vol 170 (1019) ◽  
pp. 155-173 ◽  
Keyword(s):  
Adductor Muscle ◽  
Mantle Cavity ◽  
Clockwise Rotation ◽  
Mantle Tissue ◽  
Counter Pressure ◽  
Time Period ◽  
Adductor Muscles ◽  
Inhalant Siphon ◽  
Main Activity ◽  
Low Pressures

The main activity during boring by Zirphaea crispata consists of the cyclical repetition of a group of movements, termed the boring cycle. Each boring cycle comprises the retraction of the shell to the base of the burrow, and the abrasion of the walls of the burrow by movements of the shell caused by the consecutive action of the posterior and anterior adductor muscles, supplemented by an accessory ventral adductor muscle. Each boring cycle is followed by slight anticlockwise and clockwise rotation of the animal in the burrow, while simultaneously the siphons are withdrawn and re-extended. A second type of rotational movement, resulting from changes in the position of the foot in the burrow, occurs over a longer time period, so that a circular, drop-shaped burrow is formed. The material abraded from the base of the burrow is collected into the mantle cavity and ejected as pseudofaeces from the inhalant siphon at intervals during boring. The pressures developed in the mantle cavity and haemocoele during boring are small compared with those generated by burrowing forms. During the boring cycle, low pressures (2 to 3 cm) serve to press the foot against the wall of the burrow where adhesion is aided by mucous secretion and by the action of a counter pressure from a pad of mantle tissue dorsally. Fluid is retained in the foot, and in the expanded mantle margins within the spaces of a loosely arranged connective tissue which fills these organs. The fluid filled mantle cavity and haemocoele allow the siphonal retractor muscles to act partly in antagonizing the adductor muscles, so that withdrawal of the siphons during boring restores the gape of the shell. Higher pressures (8 cm) are developed in the mantle cavity and haemocoele during the contraction of the adductor muscles and circular muscles of the siphons which is involved in the expulsion of pseudo-faeces. The tensions exerted by the pedal muscles during boring are small (2 to 2·5 g).

Cytochemical studies of the neuromuscular systems of the diporpa and juvenile stages of Eudiplozoon nipponicum (Monogenea: Diplozoidae)

Parasitology ◽  
2003 ◽  
Vol 126 (4) ◽  
pp. 349-357 ◽  
Author(s):  
T. H. ZURAWSKI ◽  
A. MOUSLEY ◽  
A. G. MAULE ◽  
M. GELNAR ◽  
D. W. HALTON
Keyword(s):  
Ventral Sucker ◽  
Adductor Muscle ◽  
The Body ◽  
Confocal Scanning Laser Microscopy ◽  
Nervous Systems ◽  
Adductor Muscles ◽  
Neuromuscular Systems ◽  
Juvenile Stages ◽  
Confocal Scanning Laser ◽  
Eudiplozoon Nipponicum

Using indirect immuno- and enzyme-cytochemical techniques, interfaced with confocal scanning laser microscopy and standard optical microscopy, neuronal pathways have been demonstrated in whole-mount preparations of the unpaired diporpae and freshly paired juvenile stages of Eudiplozoon nipponicum (Monogenea: Diplozoidae). All 3 main classes of neuronal mediators, cholinergic, aminergic and peptidergic, were identified throughout both central and peripheral elements of a well-differentiated orthogonal nervous system. Neural mapping revealed considerable overlap and similarity in staining of the nervous systems of the diporpa and adult worm. The main differences in the diporpa relate to the innervation of the temporary ventral sucker and dorsal papilla, structures which are unique to the larva and which enable fusion between worms but then disappear. Branches from the longitudinal nerve cords innervate these structures and appear to be involved in the process of somatic fusion, probably giving rise to the inter-specimen connections that later link the 2 central nervous systems in paired adult parasites. In the hindbody, there is extensive haptoral innervation associated with the developing clamps and small central hooks. Reactive neuronal components were found associated with the early stages of clamp development prior to connections being made with the extrinsic adductor muscle bundles. The muscle systems of the diporpa and juvenile stages comprise a lattice-like arrangement of circular, longitudinal and diagonal fibres that make up the body wall, together with buccal suckers, haptoral clamps and associated adductor muscles, and the transient ventral sucker. All have obvious importance to diporpae when they migrate over the gill and undertake body contact, torsion and fusion during the process of pairing. Behaviour during the pairing of diporpae is described.

Gross Structure of the Adductor Muscles of Some Pelecypods

1973 ◽  
Vol 30 (10) ◽  
pp. 1583-1585 ◽  
Author(s):  
Carol M. Morrison ◽  
Paul H. Odense
Keyword(s):  
Mytilus Edulis ◽  
Crassostrea Virginica ◽  
Adductor Muscle ◽  
Mya Arenaria ◽  
Placopecten Magellanicus ◽  
Spisula Solidissima ◽  
Arctica Islandica ◽  
Modiolus Modiolus ◽  
Adductor Muscles ◽  
Clinocardium Ciliatum

A study of the gross structure of adductor muscles of the following pelecypods showed that they conform to Morton’s grouping into the a) "Protobranchia" (Nucula proxima and Yoldia limatula), b) "shallow-burrowing lamellibranchs" (Clinocardium ciliatum, Venericardia borealis, Astarte undata, Arctica islandica, Venus mercenaria, and Spisula solidissima), c) "surface attached lamellibranchs" (Mytilus edulis, Modiolus modiolus, Modiolus demissus, Placopecten magellanicus, and Crassostrea virginica), d) "deep-burrowing and immobile lamellibranchs" (Ensis directus, Hiatella arctica, and Mya arenaria); thus providing more evidence for his classification. The adductor muscle is divided into two portions — translucent and opaque — except in the "deep-burrowing and immobile lamellibranchs", which have opaque muscles only.

scholarly journals First seasonal investigation of the fatty acid composition in three organs of the Tunisian bivalve Mactra stultorum

2019 ◽  
Vol 70 (1) ◽  
pp. 291 ◽  
Author(s):  
I. Chetoui ◽  
I. Rabeh ◽  
S. Bejaoui ◽  
K. Telahigue ◽  
F. Ghribi ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Fatty Acid Composition ◽  
Fatty Acid ◽  
Acid Composition ◽  
Dry Matter ◽  
Saturated Fatty Acids ◽  
Maximum Level ◽  
Monounsaturated Fatty Acids ◽  
Adductor Muscle ◽  
Adductor Muscles

This study reveals information for the first time about the total lipid (TL) content and fatty acid composition (FA) of Mactra stultorum (M. corallina). Three edible organs (foot, mantle and adductor muscle) were the subjects of this research in order to determine the most favorable periods for their consumption in relation to seasonal variability. The results showed lower lipid content in the adductor muscles in summer (12.73 ± 2.55 mg/g dry matter); while a higher content was observed in winter (28.97 ± 3.50 mg/g dry matter). However, similar lipid contents were observed in the mantle and foot tissues among the seasons. The fatty acid composition of Mactra stultorum adductor muscles, mantle and foot was dominated by saturated fatty acids (SFA) and polyunsaturated fatty acids (PUFA). Palmitic acid (16:0) was the major saturated fatty acid (SFA) and reached higher levels during summer in the foot (26%), mantle (21%) and adductor muscles (25%). Among PUFA, eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3) showed significant variation among seasons with high levels recorded during winter and spring. Monounsaturated fatty acids (MUFA) did not show any remarkable variation among seasons for the three studied tissues. Seasonal changes in fatty acids were observed for all samples, reaching a maximum level in winter or spring.

scholarly journals The Counter-Rotating Twin Disks in NGC 4550

1993 ◽  
Vol 153 ◽  
pp. 421-422
Author(s):  
Hans-Walter Rix ◽  
Marijn Franx ◽  
David Fisher ◽  
Garth Illingworth
Keyword(s):  
Velocity Distribution ◽  
Detailed Analysis ◽  
Major Axis ◽  
Line Of Sight ◽  
Kinematic Properties

We discuss the striking kinematic properties of the S0 galaxy NGC 4550. A detailed analysis of the line-of-sight velocity distribution (LOSVD) along the major axis shows that this galaxy contains two cold, cospatial, counterrotating disks with indistinguishable scale lengths and luminosities. The two disks, twins save the signs of their spin, are also found to have exponential luminosity profiles. We discuss qualitatively how this system might have formed.

Cadmium in the saucer scallop, Amusium balloti, from Western Australian waters: Concentrations in adductor muscle and redistribution following frozen storage

1993 ◽  
Vol 44 (6) ◽  
pp. 787 ◽  
Author(s):  
KA Francesconi ◽  
EJ Moore ◽  
LM Joll
Keyword(s):  
Digestive Gland ◽  
Frozen Storage ◽  
Adductor Muscle ◽  
Subsequent Work ◽  
Natural Origin ◽  
Remote Areas ◽  
Adductor Muscles ◽  
Wet Weight ◽  
Degree Of Redistribution ◽  
Western Australian

Geographic and seasonal variations in the concentration of cadmium in the adductor muscle of saucer scallops, Amusiurn balloti, were determined for scallops collected from five sites off the Western Australian coast throughout 1985. Mean cadmium concentrations for adductor muscles from whole frozen scallops from each of the five sites ranged from 0.41 to 1.44 mg kg-1 wet weight and were below the maximum permitted concentration of 2.0 mg kg-1 set by the Australian National Food Authority. Most of the cadmium (about 80% of the total) in the scallops was in the non-edible digestive gland. Subsequent work revealed that adductor muscles of whole frozen scallops contained more cadmium than did adductors of scallops that had been processed live because of redistribution of cadmium from the digestive gland, with the degree of redistribution depending on the time in frozen storage. Cadmium in A. balloti from Western Australian waters was likely to be of natural origin because the highest concentrations were found in animals collected in remote areas where human activities have had no significant effect.

BIOACCUMULATION AND METABOLIC EFFECTS OF ZINC ON MARINE ROCK OYSTER, CRASSOSTREA CATTUCKENSIS

2017 ◽  
Vol 23 (1) ◽  
Author(s):  
G. D. SURYAWANSHI
Keyword(s):  
Lipid Content ◽  
Adductor Muscle ◽  
Metabolic Effects ◽  
Body Parts ◽  
High Concentration ◽  
Experimental Control ◽  
Adductor Muscles ◽  
Increase Rate ◽  
High Concentrations ◽  
Detoxification Process

The Indian rock oysters, Crassostrea cattuckensis (80-90 mm shell length) were exposed to sub lethal levels of zinc for 15 days and 30 days for metal accumulation and next 15 days for metal depuration. The oysters, which served as experimental control after 15 days showed high amount of lipid (mg/100 mg) in hepatopancreas ( 3.32) followed by gills (3.20), mantle (3.08), gonad (2.90), adductor muscle (2.78) and siphon (2.11). During 15 days metal exposed oysters to (0.65) and (0.94) ppm concentrations there was changes observed in different body parts when compared to experimental control. The decreased rate upon 15 days in (0.65 ppm) concentrations was in mantle (2.96), than gill (2.22), hepatopancreas (1.72), gonad (1.59), siphon (1.51) and adductor muscle (1.50). While in (0.94 ppm) the protein was decreased in adductor muscle (2.51), gonad (1.61), siphon (1.44), gill (1.42) and it increased in mantle (3.90) and hepatopancreas (3.34) when it was compared to experimental control. Whereas upon 30 days exposure the lipid content increased among body parts in both concentration except the gills (1.35), gonads (1.97) and hepatopancreas (1.66) in higher concentration when compared with experimental control. The lipid increased in (0.65 ppm) from gonad (2.29), hepatopancreas (2.25), adductor muscle (2.22), gills (2.20), mantle (2.14) and siphon (1.44). While in (0.94 ppm) lipid increase trend was from mantle (4.27), adductor muscle (2.46) and siphon (1.42) and decreased from gonad (1.97), hepatopancreas (1.66) and gills (1.35) when compared with 30 days experimental control. During detoxification process the lipid content was increased in both concentrations except gill (2.11) in low and adductor muscle (0.99), siphon (0.74) in high concentrations when compared with respective concentrations of 15 days exposed oysters. The increase rate in low concentration was from mantle (4.32) than from adductor muscles (4.12), gonad (3.60), hepatopancreas (2.46) and siphon (1.05). In high concentration it was more in hepatopancreas (4.93) than gonad (4.42), gills (4.08) and mantle (4.01).

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