The Ligamentary System and the Segmental Musculature of Nephtys

1960 ◽  
Vol s3-101 (54) ◽  
pp. 149-176
Author(s):  
R. B. CLARK ◽  
M. E. CLARK
Keyword(s):  
Body Wall ◽  
The Body ◽  
Power Stroke ◽  
Coelomic Fluid ◽  
Unusual Structure ◽  
Shock Absorbers ◽  
Proximal Half ◽  
Unique System ◽  
Body Wall Muscles ◽  
The Impact

Nephtys lacks circular body-wall muscles. The chief antagonists of the longitudinal muscles are the dorso-ventral muscles of the intersegmental body-wall. The worm is restrained from widening when either set of muscles contracts by the combined influence of the ligaments, some of the extrinsic parapodial muscles, and possibly, to a limited extent, by the septal muscles. Although the septa are incomplete, they can and do form a barrier to the transmission of coelomic fluid from one segment to the next under certain conditions, particularly during eversion of the proboscis. Swimming is by undulatory movements of the body but the distal part of the parapodia execute a power-stroke produced chiefly by the contraction of the acicular muscles. It is suspected that the extrinsic parapodial muscles, all of which are inserted in the proximal half of the parapodium, serve to anchor the parapodial wall at the insertion of the acicular muscles and help to provide a rigid point of insertion for them. Burrowing is a cyclical process involving the violent eversion of the proboscis which makes a cavity in the sand. The worm is prevented from slipping backwards by the grip the widest segments have on the sides of the burrow. The proboscis is retracted and the worm crawls forward into the cavity it has made. The cycle is then repeated. Nephtys possesses a unique system of elastic ligaments of unusual structure. The anatomy of the system is described. The function of the ligaments appears to be to restrain the body-wall and parapodia from unnecessary and disadvantageous dilatations during changes of body-shape, and to serve as shock-absorbers against the high, transient, fluid pressures in the coelom, which are thought to accompany the impact of the proboscis against the sand when the worm is burrowing. From what is known of its habits, Nephtys is likely to undertake more burrowing than most other polychaetes.

Electrophysiology of Acanthocephalan Body Wall Muscles

1979 ◽  
Vol 82 (1) ◽  
pp. 273-280
Author(s):  
B. S. WONG ◽  
DONALD M. MILLER ◽  
T. T. DUNAGAN
Keyword(s):  
Light Microscopy ◽  
Intracellular Recording ◽  
Body Wall ◽  
Membrane Potentials ◽  
The Body ◽  
Spontaneous Potential ◽  
Body Wall Muscles ◽  
Macracanthorhynchus Hirudinaceus ◽  
Anterior Posterior

Body wall muscles of an acanthocephalan Macracanthorhynchus hirudinaceus were studied by means of scanning and light microscopy and intracellular recording of potentials. Three types of spontaneous potential changes were found: larger (L) potentials which usually exhibited overshoot and were as large as 65 mV; smaller symmetric (A) potentials approximately 15 mV in amplitude; and even smaller asymmetric (S) potentials which sometimes reached 10 mV. The potentials recorded depended upon the position of the electrode in the anterior-posterior, as well as the medialateral, axis. Tetrodotoxin eliminated L but not S potentials. Ouabain lengthened the time for depolarization of L potentials and depolarized the membrane potentials. It is suggested that the rete system activates the body wall muscles in Acanthocephala.

Positioning and maintenance of embryonic body wall muscle attachments in C. elegans requires the mup-1 gene

Development ◽  
1991 ◽  
Vol 111 (3) ◽  
pp. 667-681 ◽  
Author(s):  
P.Y. Goh ◽  
T. Bogaert
Keyword(s):  
Extracellular Matrix ◽  
Body Wall ◽  
Early Stage ◽  
Muscle Growth ◽  
The Body ◽  
Body Wall Muscle ◽  
C Elegans ◽  
Extracellular Matrix Molecule ◽  
Extracellular Matrix Components ◽  
Body Wall Muscles

As part of a general study of genes specifying a pattern of muscle attachments, we identified and genetically characterised mutants in the mup-1 gene. The body wall muscles of early stage mup-1 embryos have a wild-type myofilament pattern but may extend ectopic processes. Later in embryogenesis, some body wall muscles detach from the hypodermis. Genetic analysis suggests that mup-1 has both a maternal and a zygotic component and is not required for postembryonic muscle growth and attachment. mup-1 mutants are suppressed by mutations in several genes that encode extracellular matrix components. We propose that mup-1 may encode a cell surface/extracellular matrix molecule required both for the positioning of body wall muscle attachments in early embryogenesis and the subsequent maintenance of these attachments to the hypodermis until after cuticle synthesis.

Coordination of locomotor and cardiorespiratory networks of Lymnaea stagnalis by a pair of identified interneurones

1991 ◽  
Vol 158 (1) ◽  
pp. 37-62 ◽  
Author(s):  
N. I. Syed ◽  
W. Winlow
Keyword(s):  
Body Wall ◽  
Lymnaea Stagnalis ◽  
The Body ◽  
Whole Body ◽  
Pond Snail ◽  
Selective Ablation ◽  
The Central Nervous System ◽  
Body Wall Muscles ◽  
Bilateral Pair ◽  
Left And Right

1. The morphology and electrophysiology of a newly identified bilateral pair of interneurones in the central nervous system of the pulmonate pond snail Lymnaea stagnalis is described. 2. These interneurones, identified as left and right pedal dorsal 11 (L/RPeD11), are electrically coupled to each other as well as to a large number of foot and body wall motoneurones, forming a fast-acting neural network which coordinates the activities of foot and body wall muscles. 3. The left and right sides of the body wall of Lymnaea are innervated by left and right cerebral A cluster neurones. Although these motoneurones have only ipsilateral projections, they are indirectly electrically coupled to their contralateral homologues via their connections with L/RPeD11. Similarly, the activities of left and right pedal G cluster neurones, which are known to be involved in locomotion, are also coordinated by L/RPeD11. 4. Selective ablation of both neurones PeD11 results in the loss of coordination between the bilateral cerebral A clusters. 5. Interneurones L/RPeD11 are multifunctional. In addition to coordinating motoneuronal activity, they make chemical excitatory connections with heart motoneurones. They also synapse upon respiratory motoneurones, hyperpolarizing those involved in pneumostome opening (expiration) and depolarizing those involved in pneumostome closure (inspiration). 6. An identified respiratory interneurone involved in pneumostome closure (visceral dorsal 4) inhibits L/RPeD11 together with all their electrically coupled follower cells. 7. Both L/RPeD11 have strong excitatory effects on another pair of electrically coupled neurones, visceral dorsal 1 and right parietal dorsal 2, which have previously been shown to be sensitive to changes in the partial pressure of environmental oxygen (PO2). 8. Although L/RPeD11 participate in whole-body withdrawal responses, electrical stimulation applied directly to these neurones was not sufficient to induce this behaviour.

scholarly journals Serotonin modulates muscle function in the medicinal leech Hirudo verbana

2011 ◽  
Vol 7 (6) ◽  
pp. 885-888 ◽  
Author(s):  
Shannon P. Gerry ◽  
David J. Ellerby
Keyword(s):  
Body Wall ◽  
Longitudinal Muscle ◽  
Force Production ◽  
Physiological Saline ◽  
The Body ◽  
Hirudo Verbana ◽  
Work Production ◽  
Large Length ◽  
Body Wall Muscles

The body wall muscles of sanguivorous leeches power mechanically diverse behaviours: suction feeding, crawling and swimming. These require longitudinal muscle to exert force over an extremely large length range, from 145 to 46 per cent of the mean segmental swimming length. Previous data, however, suggest that leech body wall muscle has limited capacity for force production when elongated. Serotonin (5-HT) alters the passive properties of the body wall and stimulates feeding. We hypothesized that 5-HT may also have a role in allowing force production in elongated muscle by changing the shape of the length–tension relationship (LTR). LTRs were measured from longitudinal muscle strips in vitro in physiological saline with and without the presence of 10 µM 5-HT. The LTR was much broader than previously measured for leech muscle. Rather than shifting the LTR, 5-HT reduced passive muscle tonus and increased active stress at all lengths. In addition to modulating leech behaviour and passive mechanical properties, 5-HT probably enhances muscle force and work production during locomotion and feeding.

Observations in the Skin Pigment and Amoebocytes, and the Occurrence of Phenolases in the Coelomic Fluid of Holothuria Forskali Delle Chiaje

1953 ◽  
Vol 31 (3) ◽  
pp. 529-539 ◽  
Author(s):  
Norman Millott
Keyword(s):  
Body Wall ◽  
Black Body ◽  
The Body ◽  
Coelomic Fluid ◽  
Histological Evidence ◽  
Oxidase System ◽  
Complete Investigation ◽  
Skin Pigment

The black body-wall pigment of Holothuria forskali shows the characteristics of melanin.From histological evidence it appears that the pigment is formed in association with the amoebocytes of the coelomic fluid, which eliminate the pigment in the body wall.The amoebocytes contain a phenolase system, distinct from the cytochromecytochrome oxidase system, with the properties of tyrosinase.The relation of these findings to those of a preceding and more complete investigation into melanogenesis in Diadema is discussed.

Excretion of thiosulphate, the main detoxification product of sulphide, by the lugworm arenicola marina L

1999 ◽  
Vol 202 (7) ◽  
pp. 855-866 ◽  
Author(s):  
K. Hauschild ◽  
W.M. Weber ◽  
W. Clauss ◽  
M.K. Grieshaber
Keyword(s):  
Body Wall ◽  
Sea Water ◽  
The Body ◽  
Cell Junctions ◽  
Metabolic Inhibitors ◽  
Coelomic Fluid ◽  
Arenicola Marina ◽  
Double Exponential ◽  
Electrophysiological Measurements ◽  
Double Exponential Function

Thiosulphate, the main sulphide detoxification product, is accumulated in the body fluids of the lugworm Arenicola marina. The aim of this study was to elucidate the fate of thiosulphate. Electrophysiological measurements revealed that the transepithelial resistance of body wall sections was 76+/−34 capomega cm2 (mean +/− s.d., N=14), indicating that the body wall of the lugworm is a leaky tissue in which mainly paracellular transport along cell junctions takes place. The body wall was equally permeable from both sides to thiosulphate, the permeability coefficient of which was 1. 31×10(−)3+/−0.37×10(−)3 cm h-1 (mean +/− s.d., N=30). No evidence was found for a significant contribution of the gills or the nephridia to thiosulphate permeation. Thiosulphate flux followed the concentration gradient, showing a linear correlation (r=0.997) between permeated and supplied (10–100 mmol l-1) thiosulphate. The permeability of thiosulphate was not sensitive to the presence of various metabolic inhibitors, implicating a permeation process independent of membrane proteins and showing that the lugworm does not need to use energy to dispose of the sulphide detoxification product. The present data suggest a passive permeation of thiosulphate across the body wall of A. marina. In live lugworms, thiosulphate levels in the coelomic fluid and body wall tissue decreased slowly and at similar rates during recovery from sulphide exposure. The decline in thiosulphate levels followed a decreasing double-exponential function. Thiosulphate was not further oxidized to sulphite or sulphate but was excreted into the sea water.

Differentiation of Ectoderm Implanted into the Primordium of the Limb Bud in the Amphibian Embryo and its Influence upon the Limb

1946 ◽  
Vol 22 (3-4) ◽  
pp. 101-106
Author(s):  
WALTER BRANDT
Keyword(s):  
Body Wall ◽  
Distal Part ◽  
The Body ◽  
Limb Bud ◽  
Muscle Fibres ◽  
Tail Bud ◽  
Amphibian Embryo ◽  
Microscopical Analysis ◽  
Proximal Half ◽  
Host Embryo

1. A microscopical analysis was made concerning the differentiation of ectoderm cut from the tip of the tail-bud of an amphibian embryo (Amblystoma mexicanum, stages 35-37, Harrison) after its implantation into the primordium of the limb-bud of a host embryo 3-5 weeks after operation. 2. The ectoderm which lay deep in the tissues of the limb differentiated either into solid epithelial cords or into cysts. 3. The ectoderm which was attached outside the limb differentiated into notched ectodermal elevations which included a mesenchymal core. 4. A microscopical analysis was made concerning the development of deformities of limbs as the result of the operation. 5. The scapula may be divided into isolated pieces, bundles of muscle fibres separating the pieces from each other. 6. A supernumerary piece of cartilage can develop close to the cartilage of the scapula. 7. The suprascapula may be absent and its place taken by a mass of muscle fibres. 8. A phocomelias may be produced when the whole length of the humerus and the elbow-joint lies inside the body wall. In this case the implanted ectoderm covers the area where the limb would normally develop. 9. The humerus may be reduplicated. 10. The humerus may be too short. 11. The proximal half of the humerus may possess a diameter different from that of the distal half. 12. One skeletal element only of the forearm (radius or ulna) may be present when the place which would normally be occupied by one of these elements was taken by implanted ectoderm. 13. The elements of the carpus and of the hand may appear irregularly scattered throughout the tissues of the distal part of the limb. In these cases the implanted ectoderm was attached to the surface of the distal end of the limb. 14. The fingers can show: (a) abnormal positions, (b) abnormal numbers, (c) syndactylias, (d) one finger too long, others too short.

Memoirs: Studies on the Structure, Development, and Physiology of the Nephridia of Oligochaeta VI. The Physiology of Excretion and the Significance of the Enteronephric Type of Nephridial System in Indian Earthworms

1945 ◽  
Vol s2-85 (340) ◽  
pp. 343-389
Author(s):  
KARM NARAYAN BAHL
Keyword(s):  
Large Scale ◽  
Body Wall ◽  
Chloride Content ◽  
The Body ◽  
Regulatory Function ◽  
Coelomic Fluid ◽  
Brownish Yellow ◽  
Terrestrial Animal ◽  
First Time ◽  
Blood Pigment

1. In an earthworm, as in most aquatic invertebrates, urea and ammonia form the main bulk of nitrogenous excretion and there is no trace of uric acid. These excretory products are first formed in the body-wall and gut-wall, pass therefrom into the coelomic fluid and blood, and are thence eliminated to the exterior by the nephridia. In Pheretima urea and ammonia pass out from the nephridia to the exterior either directly through the skin or through the two ends of the gut. 2. Ammonia and urea have been estimated for the first time in the blood, coelomic fluid, and urine of the earthworm. It has been shown that blood is not a mere carrier of oxygen, as Rogers believed, but that it also takes part in carrying urea and ammonia from the body-wall and gut-wall to the nephridia. The blood of the earthworm does not coagulate, indicating absence of fibrinogen. 3. The role of the nephridia in excretion and osmotic regulation has been determined. A comparison of the osmotic pressures of blood, coelomic fluid, and urine shows that the coelomic fluid is hypotonic to the blood, and that urine is markedly hypotonic both to the blood and coelomic fluid. The protein and chloride contents of the blood, coelomic fluid, and urine have been determined with a view to elucidate the differences in their osmotic pressures. It has been found that the urine contains the merest trace of protein, but that the amount of proteins in the blood is about eight times that contained in the plasma of the coelomic fluid. On the contrary, the chloride content of the coelomic fluid-plasma is about 60 per cent, higher than that of the blood-plasma. 4. The part of urine which is excreted from the blood is probably a protein-free filtrate, but the nephridia reabsorb all the proteins passing into them with the coelomic fluid-plasma. Similarly, there is a reabsorption of chlorides on a large scale from the initial nephridial filtrate during its passage through the nephridia. 5. A convenient method has been devised for collecting urine of the earthworm, which has made it possible to collect as much as 25 c.c. of urine in two and a half hours. The rate of excretion of the urine has been determined and it has been found that in an earthworm living in water the outflow of urine in twenty-four hours must be more than 45 per cent, of its body-weight. 6. It seems that an earthworm, when submerged in water, can live like a fresh water animal, and its gut acts as an osmoregulatory organ in addition to the nephridia, but in the soil it lives like a terrestrial animal and the osmo-regulatory function is adequately discharged by the nephridia alone which reabsorb chlorides and proteins, and are also active in the conservation of water. In Pheretima and other earthworms with an enteronephric type of nephridial system, the gut takes a prominent part in reabsorbing the water of the nephridial fluid and conserving water to its maximum extent. 7. The phagocytic section (ciliated middle tube) believed by Schneider to be absent in the nephridia of Pheretima has been shown to be distinctly present; it is also present in the nephridia of Lampito , Eutyphoeus, and Tonoscolex. The brownish yellow granules characteristic of this phagocytic section form a heavy deposit in the septal nephridia of Pheretima posthuma, heavier than that described in Lumbricus. The deposit increases with the age of the earthworm and forms a ‘storage excretory product’. 8. Spectroscopic examination has revealed that these brownish yellow granules, so far believed to be of guanine, are really blood-pigment granules, since a pyridine solution of them shows the two characteristic bands of haemochromogen. With regard to the blood-pigment, the nephridia function as ‘storage kidneys’. 9. The mechanism of nephridial excretion of the earthworm can be analysed into processes of filtration, reabsorption, and chemical transformation. 10. It is probable that the dorsal and ventral phagocytic organs of earthworms are additional excretory organs.

Calsequestrin, a calcium sequestering protein localized at the sarcoplasmic reticulum, is not essential for body-wall muscle function in Caenorhabditis elegans

2000 ◽  
Vol 113 (22) ◽  
pp. 3947-3958 ◽  
Author(s):  
J.H. Cho ◽  
Y.S. Oh ◽  
K.W. Park ◽  
J. Yu ◽  
K.Y. Choi ◽  
...  
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Calcium Binding ◽  
Body Wall ◽  
Functional Characterization ◽  
The Body ◽  
Body Wall Muscle ◽  
C Elegans ◽  
Muscle Formation ◽  
Body Wall Muscles

Calsequestrin is the major calcium-binding protein of cardiac and skeletal muscles whose function is to sequester Ca(2+)in the lumen of the sarcoplasmic reticulum (SR). Here we describe the identification and functional characterization of a C. elegans calsequestrin gene (csq-1). CSQ-1 shows moderate similarity (50% similarity, 30% identity) to rabbit skeletal calsequestrin. Unlike mammals, which have two different genes encoding cardiac and fast-twitch skeletal muscle isoforms, csq-1 is the only calsequestrin gene in the C. elegans genome. We show that csq-1 is highly expressed in the body-wall muscles, beginning in mid-embryogenesis and maintained through the adult stage. In body-wall muscle cells, CSQ-1 is localized to sarcoplasmic membranes surrounding sarcomeric structures, in the regions where ryanodine receptors (UNC-68) are located. Mutation in UNC-68 affects CSQ-1 localization, suggesting that the two possibly interact in vivo. Genetic analyses of chromosomal deficiency mutants deleting csq-1 show that CSQ-1 is not essential for initiation of embryonic muscle formation and contraction. Furthermore, double-stranded RNA injection resulted in animals completely lacking CSQ-1 in body-wall muscles with no observable defects in locomotion. These findings suggest that although CSQ-1 is one of the major calcium-binding proteins in the body-wall muscles of C. elegans, it is not essential for body-wall muscle formation and contraction.

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