Control of ‘Pulmonary’ Pressure and Coordination with Gill Ventilation in the Shore Crab Carcinus Maenas

1991 ◽  
Vol 155 (1) ◽  
pp. 147-164
Author(s):  
K. P. RAJASHEKHAR ◽  
J. L. WILKENS
Keyword(s):  
Muscle Activity ◽  
Pressure Fluctuations ◽  
Carcinus Maenas ◽  
Circulatory System ◽  
Muscular Activity ◽  
Pattern Generator ◽  
Shore Crab ◽  
Positive Pressure ◽  
Gill Ventilation

In the shore crab, Carcinus maenas (L.), forward ventilation creates negative pulses of hydrostatic pressure while reversed ventilation causes dramatic positive pressure fluctuations in the branchial chamber. These pressures are transmitted via the gills to the haemolymph of the open circulatory system. The branchiostegal sinus, which is a compliant chamber, may function as a reservoir for displaced haemolymph and may operate as an accessory pump driven by the action of the dorsoventral (DV) muscles. A band of dorsoventral muscles controls the volume of the branchiostegal sinuses. The muscular activity is coordinated with ventilatory activity and may assist in regulating pressure fluctuations caused by ventilatory pressure pulses. During a ventilatory reversal, the haemolymph displaced from the gills is added to the volume of haemolymph in the open circulatory system and this haemolymph may be accommodated in the branchiostegal sinus by relaxation of the DV muscles. Artificially regulating the pressure either in the branchial chamber or in the branchiostegal sinus reflexively alters DV muscle activity, which suggests the occurrence of baroreceptors in this crab. The branchiostegal nerve that innervates the DV muscles contains five neurones identified by cobalt backfills. Three of them are median and two are contralateral. The dendritic field of each neurone is confined to its respective hemiganglia. The electrical activity of one of the motoneurones in the branchiostegal nerve corresponds to the activity of the DV muscles. In vitro observations of the activity of branchiostegal motoneurones in relation to ventilatory motoneurone activity indicate that both are centrally coupled and support the hypothesis that the branchiostegal motoneurones are influenced by the ventilatory central pattern generator.

scholarly journals Analysis of the Scaphognathite Ventilatory Pump in the Shore Crab Carcinus Maenas: I. WORK AND POWER

1984 ◽  
Vol 113 (1) ◽  
pp. 55-68 ◽  
Author(s):  
A. JOFFRE MERCIER ◽  
JERREL L. WILKENS
Keyword(s):  
Carcinus Maenas ◽  
Pattern Generator ◽  
Ventilation Rate ◽  
Isometric Tension ◽  
Shore Crab ◽  
Stroke Work ◽  
First Approximation ◽  
Gill Ventilation ◽  
Ventilation Rates ◽  
Ventilatory Muscles

Measurements of branchial pressure and ventilation volumes were used to calculate the work and power of gill ventilation in Carcinus maenas, during spontaneous as well as forced unilateral ventilation. With increasing ventilation rate (fR), the stroke work increases as a result of an elevated gradient of branchial pressure, while power output increases as a result of enhancement of both the pressure gradient and the flow rate. To a first approximation, the stroke work is proportional to fR1.5, and the power out-put is proportional to fR2.5. The available evidence suggests that flow is mainly laminar through the branchial chamber but turbulent through the pumping chamber. Evidence is presented which suggests that the crab is able to vary the resistance to the flow of branchial water. The increased branchial pressure at elevated ventilation rates constitutes an increased load on the ventilatory muscles. Measurements of isometric tension confirm that the muscles compensate for this increased load by generating greater force. Electromyograms support the notion that the change in force results from appropriate changes in the output from the central pattern generator.

The Distribution of P O2 and Hydrostatic Pressure Changes Within the Branchial Chambers in Relation to GILL VENTILATION OF THE SHORE CRAB CARCINUS MAENAS L

1969 ◽  
Vol 51 (1) ◽  
pp. 203-220
Author(s):  
G. M. HUGHES ◽  
B. KNIGHTS ◽  
C. A. SCAMMELL
Keyword(s):  
Hydrostatic Pressure ◽  
Ventilation System ◽  
Carcinus Maenas ◽  
Pressure Change ◽  
Shore Crab ◽  
Positive Pressure ◽  
Transparent Plastic ◽  
Gill Lamellae ◽  
Minimum Disturbance ◽  
Pressure Changes

1. A technique is described for replacing part of the branchiostegite of Carcinus maenas by a transparent plastic ‘window’ for direct observation of the gills in situ with minimum disturbance. 2. Observation of dye streams shows that most water enters the hypobranchial space through the Milne-Edwards openings above the chelae, flowing anteriorly and/or posteriorly to ventilate most of gills 3-8. Water also enters above the pereiopods to ventilate the rest of the gills. Water passes from the hypobranchial to the epibranchial space, confirming that there is a counterflow with respect to the circulation of blood through the gill lamellae. 3. By sampling water at different points in the branchial system, patterns of oxygen removal were studied. The gradients confirmed the direction of water flow observed by the use of dyes. 4. Rhythmic changes in hydrostatic pressure in normal forward-pumping of 3-12 mm. H2O were recorded from the branchial cavities, superimposed on a maintained negative pressure relative to that outside the crab of 0-10 mm. H2O. Reversals produced a brief positive pressure change of 0-22 mm. H2O. 5. The possible relationships of the rhythmic pressure changes to scaphognathite movements are discussed. 6. The role of reversals is discussed and it is concluded that their primary function during ventilation is in helping to clean the ventrally facing gill surfaces. But they are also important in respiration under certain special conditions which arise during the normal life of the animal. 7. The utilization of O2 during its passage over the gills is low (7-23%) in spite of the counterflow. Possible explanations of this are discussed in relation to a model of the whole ventilation system.

The Uptake of Cadmium Into the Haemolymph of the Shore Crab Carcinus Maenas: The Relationship With Copper and Other Divalent Cations

1977 ◽  
Vol 67 (1) ◽  
pp. 147-161
Author(s):  
D. A. WRIGHT
Keyword(s):  
Divalent Cations ◽  
Cadmium Concentration ◽  
Carcinus Maenas ◽  
Shore Crab ◽  
Cadmium Level ◽  
Haemolymph Protein ◽  
Urine Cadmium ◽  
The Relationship

When Carcinus was exposed to 20 μ-mol l−1 cadmium, the haemolymph cadmium level was initially dependent upon the salinity of the external medium. After 14 days the mean haemolymph cadmium level in 50% s.w. animals was nearly twice that of 100% s.w. animals. This trend was not sustained, however, and the situation was complicated by occasional inconsistent values. In both in vivo and in vitro conditions nearly all the haemolymph cadmium becomes bound to haemolymph protein within a few days. The relationship between haemolymph cadmium, copper and protein concentration has been investigated. Although the latter are highly correlated with each other, cadmium formed a significant positive relationship with haemolymph copper (r = 0.523) and protein (r = 0.533) only after 3–4 weeks uptake. Exposure to 20 μ-mol l−1 cadmium has no obvious effects on haemolymph protein and copper concentrations, which are clearly dependent on feeding status. Mortalities among experimental animals were often preceded by a rise in haemolymph cadmium concentration. This is usually seen before there are any obvious signs of tissue breakdown. Urine cadmium loss is probably unimportant as a pathway for the elimination of this metal. Urine cadmium concentrations often exceeded serum cadmium levels indicating that cadmium may sometimes be eliminated in bound form.

scholarly journals Crustacean hyperglycaemic hormone (CHH)-like peptides and CHH-precursor-related peptides from pericardial organ neurosecretory cells in the shore crab, Carcinus maenas, are putatively spliced and modified products of multiple genes

2001 ◽  
Vol 356 (1) ◽  
pp. 159-170 ◽  
Author(s):  
Heinrich DIRCKSEN ◽  
Detlef BÖCKING ◽  
Uwe HEYN ◽  
Christa MANDEL ◽  
J. Sook CHUNG ◽  
...  
Keyword(s):  
Signal Peptide ◽  
Carcinus Maenas ◽  
Penaeid Shrimp ◽  
Neurosecretory Cells ◽  
Shore Crab ◽  
Amino Acid Peptide ◽  
C Terminus ◽  
Gene Structures

About 24 intrinsic neurosecretory neurons within the pericardial organs (POs) of the crab Carcinus maenas produce a novel crustacean hyperglycaemic hormone (CHH)-like peptide (PO-CHH) and two CHH-precursor-related peptides (PO-CPRP I and II) as identified immunochemically and by peptide chemistry. Edman sequencing and MS revealed PO-CHH as a 73 amino acid peptide (8630Da) with a free C-terminus. PO-CHH and sinus gland CHH (SG-CHH) share an identical N-terminal sequence, positions 1–40, but the remaining sequence, positions 41–73 or 41–72, differs considerably. PO-CHH may have different precursors, as cDNA cloning of PO-derived mRNAs has revealed several similar forms, one exactly encoding the peptide. All PO-CHH cDNAs contain a nucleotide stretch coding for the SG-CHH41–76 sequence in the 3′-untranslated region (UTR). Cloning of crab testis genomic DNA revealed at least four CHH genes, the structure of which suggest that PO-CHH and SG-CHH arise by alternative splicing of precursors and possibly post-transcriptional modification of PO-CHH. The genes encode four exons, separated by three variable introns, encoding part of a signal peptide (exon I), the remaining signal peptide residues, a CPRP, the PO-CHH1–40/SG-CHH1–40 sequences (exon II), the remaining PO-CHH residues (exon III) and the remaining SG-CHH residues and a 3′-UTR (exon IV). Precursor and gene structures are more closely related to those encoding related insect ion-transport peptides than to penaeid shrimp CHH genes. PO-CHH neither exhibits hyperglycaemic activity in vivo, nor does it inhibit Y-organ ecdysteroid synthesis in vitro. From the morphology of the neurons it seems likely that novel functions remain to be discovered.

Host Defence Reactions of the Shore Crab, Carcinus Maenas (L.), in Vitro

1978 ◽  
Vol 58 (2) ◽  
pp. 367-379 ◽  
Author(s):  
Valerie J. Smith ◽  
N. A. Ratcliffe
Keyword(s):  
Physiological Stress ◽  
Carcinus Maenas ◽  
Shore Crab ◽  
Aquatic Environments ◽  
Intensive Culture ◽  
Defence Mechanisms ◽  
Culture Methods ◽  
Economic Role ◽  
Defence Reactions

The Crustacea play an important economic role in the marine and aquatic environments not only as a food source but also in the productivity of the fisheries. Exploitation of these resources has led to a need for intensive culture methods which impose physiological stress on the animals and consequently increase the incidence of disease. The need to reduce the lethal and debilitating effects of pathogens has stimulated a renewed interest in the defence mechanisms of the Crustacea.

Rostral Versus Caudal Differences in Mechanical Entrainment of the Lamprey Central Pattern Generator for Locomotion

2008 ◽  
Vol 99 (5) ◽  
pp. 2408-2419 ◽  
Author(s):  
Eric D. Tytell ◽  
Avis H. Cohen
Keyword(s):  
Spinal Cord ◽  
Central Pattern Generator ◽  
Muscle Activity ◽  
Pattern Generator ◽  
The Body ◽  
Phase Lag ◽  
Neural Basis ◽  
Phase Gradient

In fishes, undulatory swimming is produced by sets of spinal interneurons constituting a central pattern generator (CPG). The CPG generates waves of muscle activity that travel from head to tail, which then bend the body into wave shapes that also travel from head to tail. In many fishes, the wavelengths of the neural and mechanical waves are different, resulting in a rostral-to-caudal gradient in phase lag between muscle activity and bending. The neural basis of this phase gradient was investigated in the lamprey spinal cord using an isolated in vitro preparation. Fictive swimming was induced using d-glutamate and the output of the CPG was measured using suction electrodes placed on the ventral roots. The spinal cord was bent sinusoidally at various points along its length. First, the ranges of entrainment were estimated. Middle segments were able to entrain to frequencies approximately twice as high as those at end segments. Next, phase lags between centers of ventral root bursts and the stimulus were determined. Two halves of the cycle were identified: stretching and shortening of the edge of spinal cord on the same side as the electrode. Stimuli at rostral segments tended to entrain segmental bursting at the beginning of the stretch phase, almost 50% out of phase with previously measured in vivo electromyography data. Stimuli at caudal segments, in contrast, entrained segments at the end of stretch and the beginning of shortening, approximately the same phase as in vivo data.

Host Defence Reactions of the Shore Crab, Carcinus Maenas (L.): Clearance and Distribution of Injected Test Particles

1980 ◽  
Vol 60 (1) ◽  
pp. 89-102 ◽  
Author(s):  
Valerie J. Smith ◽  
N. A. Ratcliffe
Keyword(s):  
Specific Activity ◽  
Carcinus Maenas ◽  
Shore Crab ◽  
Foreign Material ◽  
Defence Mechanisms ◽  
Test Particles ◽  
Cellular Defence ◽  
Defence Reactions

It is well established that crustaceans can overcome infection and clear foreign material introduced into the circulation (Cornick & Stewart, 1968; Tyson & Jenkin, 1973; Stewart & Zwicker, 1974). In the absence of vertebrate-type specific acquired immunity, the non-specific activity mediated by the circulating blood cells appears to be of considerable importance in resistance to disease (Sindermann, 1971). Among the cellular defence mechanisms of the Crustacea, phagocytosis has received most attention and there is considerable evidence from in vitro studies that this process plays an important part in the removal of foreign particles from the blood (McKay & Jenkin, 1970a; Paterson & Stewart, 1974; Tyson & Jenkin, 1974; Paterson, Stewart & Zwicker, 1976; Smith & Ratcliffe, 1978). Such studies, however, may not always reflect the true in vivo condition, and there is a great need for correlated in vitro and in vivo investigations.

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