Reducing Activity and the Formation of Base in the Shore Crab, Carcinus Maenas

1985 ◽  
Vol 65 (2) ◽  
pp. 505-530 ◽  
Author(s):  
Peter S. B. Digby
Keyword(s):  
Outer Surface ◽  
Biological Material ◽  
Sea Water ◽  
Carcinus Maenas ◽  
Water Salinity ◽  
Shore Crab ◽  
Calcareous Deposits ◽  
Reducing Activity ◽  
Diffusion Potentials ◽  
Active Processes

Crustacean cuticle consists essentially of chitin impregnated and coated with protein which is tanned with quinone (Dennell, 1947a). The outer surface is most heavily tanned, and the cuticle is further strengthened by calcification. The various theories as to the mechanism of calcification in crustacean and other biological material have been reviewed briefly by Digby (1967). Most appear unsatisfactory for various reasons, and evidence was outlined that calcification might arise from the formation of base by processes which are essentially electrochemical in origin. The quinone-tanned protein of the cuticle is electrically semiconducting and supports electrode action in suitable gradients of potential (Digby, 1965), and small potential differences may arise by diffusion or by active processes. Thus the deposition of calcareous salts might arise partly at least by action comparable to that which takes place at a metallic cathode. In support of this, the position of the initial calcareous deposits in Carcinus maenas (L.) was found to change with the gradient of sea-water salinity in the manner expected if some control were exercised by diffusion potentials, acting across a thin semiconducting layer to generate small changes of pH (Digby, 1968).

Zinc Regulation in the Lobster Homarus Gammarus: Importance of Different Pathways of Absorption and Excretion

1986 ◽  
Vol 66 (1) ◽  
pp. 175-199 ◽  
Author(s):  
G. W. Bryan ◽  
L. G. Hummerstone ◽  
Eileen Ward
Keyword(s):  
Sea Water ◽  
Carcinus Maenas ◽  
The Body ◽  
Shore Crab ◽  
Freshwater Crayfish ◽  
Uptake Mechanism ◽  
Major Pathway ◽  
Homarus Gammarus ◽  
Wide Range ◽  
Body Concentration

Zinc is one of the most important of the essential trace metals and more than 90 zinc-containing enymes and proteins have been discovered: furthermore, zinc increases the activity of many other enzymes (Vallee, 1978). It is not surprising, therefore, that in some groups of animals the body concentration is regulated against fluctuations in intake. Decapod crustaceans comprise one such group, although the ways in which regulation is achieved vary from species to species. In the freshwater crayfish, Austropotamobius pallipes, excretion in the faeces is a major pathway for removing zinc (Bryan, 1967a) whereas in the shore crab Carcinus maenas losses over the body surface also assume considerable importance (Bryan, 1966). On the other hand, preliminary work on the lobster Homarus gammarus (formerly H. vulgaris) suggests that in this species urinary excretion plays a major role in regulation (Bryan, 1964). The present work continues the study of zinc regulation in lobsters and its main aims are: (1) to measure rates of absorption from sea water over a wide range of concentrations and study the uptake mechanism; (2) to examine absorption from the stomach under different conditions; (3) to determine the relative importance of different pathways for the removal of zinc in response to various levels of intake.

Suspension feeding in larval crabs (Carcinus maenas)

1993 ◽  
Vol 73 (1) ◽  
pp. 207-211 ◽  
Author(s):  
Jan Robert Factor ◽  
Barbara L. Dexter
Keyword(s):  
Size Range ◽  
Sea Water ◽  
Carcinus Maenas ◽  
Epifluorescence Microscopy ◽  
Shore Crab ◽  
Suspension Feeding ◽  
Natural Diet ◽  
Crab Larvae ◽  
Water Suspensions ◽  
Detrital Particles

First-stage zoeal larvae of the green (shore) crab, Carcinus maenas (Crustacea: Brachyura: Portunidae), ingested three types of particles offered in sea-water suspensions. In experiments using two types of fluorescent particles (1–2 µm and 1–7 µm ) and living Dunaliella tertiolecta cells (5–7 µm), particles were ingested in at least 40% of the zoeae examined with brightfield, darkfield, and epifluorescence microscopy. These results suggest that green crab larvae may be capable of utilizing planktonic particles in the size range of bacteria, small algal cells, and organically-enriched detrital particles in their natural diet.

Respiratory and Circulatory Adjustments during Aquatic Treadmill Exercise in the European Shore Crab Carcinus Maenas

1992 ◽  
Vol 162 (1) ◽  
pp. 37-54 ◽  
Author(s):  
N. M. HAMILTON ◽  
D. F. HOULIHAN
Keyword(s):  
Sea Water ◽  
Carcinus Maenas ◽  
Fold Increase ◽  
Co2 Exchange ◽  
Total Carbon ◽  
Shore Crab ◽  
Rate Of Oxygen Consumption ◽  
Novel Design ◽  
Cardiac Stroke Volume ◽  
Aquatic Treadmill

Carcinus maenas (L.) were exercised using a novel design of aquatic treadmill respirometer. Tethered exercise was performed in sea water at 5.8 m min−1 for 5min. The rate of oxygen consumption and the heart and scaphognathite beat rates increased at the onset of exercise, reaching a steady state within 180 s. The estimated haemolymph flow rate rose 2.6-fold during exercise, achieved by a 1.8-fold increase in heart rate and a 1.5-fold increase in the estimated cardiac stroke volume. The haemolymph total oxygen content difference increased significantly during exercise. Haemolymph total carbon dioxide content did not change significantly during exerise, but haemolymph pH deceased as a result of an L-lactate-induced metabolic acidosis. The acidosis may also have led to a reduced Bohr shift. It is concluded that O2 and CO2 exchange were not impaired during exercise and that C. maenas relied primarily upon O2 to fuel underwater running at 5.8 m min−1.

Calcification in the Shore Crab, Carcinus Maenas (L.): pH and the Precipitation of Carbonate From Sea Water and Blood

1984 ◽  
Vol 64 (1) ◽  
pp. 233-248 ◽  
Author(s):  
Peter S. B. Digby
Keyword(s):  
Sea Water ◽  
Carcinus Maenas ◽  
Shore Crab ◽  
Local Formation ◽  
Mixed Composition ◽  
Blood Ph ◽  
Water Ph ◽  
Dilute Suspensions ◽  
Series Of Experiments ◽  
The Mean

Much evidence has suggested that calcification in Carcinus and certain other marine organisms may arise at least partly by the local formation of base. The extent of changes of pH needed to precipitate calcium carbonate from sea water or from the blood of the crab are not known with certainty. These have been investigated, using sea water and crabs from the coast of Maine.Mean sea water pH, mostly as measured in aerated samples used for experiments in the laboratory, was 8·00, a little below the values commonly found close to the shore in summer. The corresponding mean blood pH was 7·12. Crushing calcified crab cuticle in sea-water raised the pH, showing the sea water to be below saturation with the salts concerned. The rise in pH was slightly greater in the more dilute suspensions, an effect attributed to the mixed composition of the calcifying salts. Thus in one group of experiments cuticle crushed in sea water in proportions 1:20 and 112·7 raised its pH by 0·66 and 0·62 units respectively, and extrapolation suggested that interstitial fluid of almost zero volume would equilibrate at 0·38 pH units above sea water. Crushing cuticle in crab blood in proportion 1:2·7 raised its pH by 1·03 units, showing the plasma also to be unsaturated with carbonate.Carbonates were precipitated from sea water by rendering it alkaline with sodium hydroxide; in four experiments the first crystallites were found in samples in which in 3 days after addition of base pH had fallen to between 8·46 and 9·30. In a longer series of experiments with crab plasma, crystals were first seen in samples in which after three days the mean pH had fallen to 8–09. Crystallites at the surface formed mosaics of spherulites closely resembling those of normal crab cuticle.

Reducing activity and the formation of base in the coralline algae: an electrochemical model

1979 ◽  
Vol 59 (2) ◽  
pp. 455-477 ◽  
Author(s):  
P. S. B. Digby
Keyword(s):  
Carbon Dioxide ◽  
Outer Surface ◽  
Sea Water ◽  
Carbonic Anhydrase Activity ◽  
Coralline Algae ◽  
Platinum Foil ◽  
Surrounding Water ◽  
Electrode Potentials ◽  
Acid And Base ◽  
Reducing Activity

SUMMARY AND CONCLUSIONSIn the process of calcification in the coralline algae, Clathromorphum and Corallina, the energy is derived from photosynthesis; the outer surface evolves carbon dioxide while calcium carbonate is deposited between the algal filaments. Evidence suggests that calcification may be brought about essentially by separation of acid and base followed by preferential removal of an acid component in the form of carbon dioxide.These algae show strong oxidase, catalase and carbonic anhydrase activity, consistent with the processes postulated. The calcified algal thallus is normally reducing. Platinum electrode potentials, Eh, measured on and immediately below the outer surface of fresh and healthy Clathromorphum crust following abrasion ranged from 50 to 100 mV, some 150–370 mV negative to that of the surrounding water at the time. These potentials in the alga were most reducing after the material had been exposed to strong sunlight. Eh potentials, measured by electrodes of platinum foil attached to the outer surface of Clathromorphum in such a way as to shield it from light and from gaseous exchange from the sea water, reached values between 113 and -182 mV, or up to 480 mV negative to the Eh of the surrounding sea water.Oxidation of crude suspensions of crushed fresh material showing reducing activity resulted in the production of base by removal of hydrogen ions. The amount of base so formed was greater when suspensions were first incubated out of contact with air for periods of up to several days, reducing conditions being enhanced by respiration of the alga alone or in conjunction with bacterial growth.

The Effect of Salinity on Cadmium Uptake by the Tissues of the Shore Crab Carcinus Maenas

1977 ◽  
Vol 67 (1) ◽  
pp. 137-146
Author(s):  
D. A. WRIGHT
Keyword(s):  
Sea Water ◽  
Cadmium Concentration ◽  
Carcinus Maenas ◽  
Maximum Level ◽  
Cadmium Accumulation ◽  
Cadmium Uptake ◽  
Whole Body ◽  
Shore Crab ◽  
Salinity Effect ◽  
Wet Weight

Cadmium accumulation by the haemolymph, gills and carapace of the shore crab Carcinus maenas (L.) was significantly higher in dilute sea water. This was reflected in the whole-body cadmium concentrations. There was no salinity effect with the hepatopancreas or muscle cadmium concentration. Over a 68-day period, cadmium was steadily accumulated by the carapace, with the salinity effect becoming increasingly apparent. In 50 % sea water the gill cadmium concentration apparently reached a maximum level after about 2 weeks of uptake. This was eventually overtaken by the tissue cadmium concentration in the gills of 100 % s.w. animals. After about 48 days the salinity effect had disappeared and the gill cadmium concentration of both 50% and 100% s.w. animals (in 20μ-mol Cd l−1 = 2.3 mg l−1) remained at approximately 0.3 μ-mol Cd g−1 (= 33.7 mg kg−1) wet weight of tissue. The hepatopancreas cadmium also levelled off at about this concentration although no salinity effect was apparent. When animals loaded with cadmium for a 37-day period were returned to clean sea water, their whole body cadmium concentration fell by about 50 % after 11 days. Losses from carapace and gills were important components of this reduction in cadmium concentration.

The Effect of Calcium on Cadmium Uptake by the Shore Crab Carcinus Maenas

1977 ◽  
Vol 67 (1) ◽  
pp. 163-173
Author(s):  
D. A. WRIGHT
Keyword(s):  
Inverse Relationship ◽  
Calcium Concentration ◽  
Sea Water ◽  
External Medium ◽  
Carcinus Maenas ◽  
Inverse Correlation ◽  
Whole Body ◽  
Shore Crab ◽  
Significant Inverse Relationship ◽  
External Calcium

The accumulation of cadmium by the shore crab Carcinus maenas (L.) is to some extent dependent upon the calcium concentration of the external medium. This effect is apparently independent of the overall salinity of the external medium and may at least partially explain previous reports of a ‘salinity effect’. Haemolymph cadmium has a highly significant inverse relationship with the external calcium concentration. This effect is less obvious with other tissues, although the whole body cadmium has a significant inverse correlation with the external calcium concentration. Both the haemolymph and gill show a significant inverse relationship between tissue cadmium and calcium. When postmoult animals were exposed to 20μ-mol l−1 Cd in 100% s.w., high concentrations of both calcium and cadmium appeared in the haemolymph. Postmoult animals in cadmium-free sea water generally had a lower haemolymph calcium concentration than intermoult animals, and the rise in haemolymph calcium seen in the presence of cadmium may indicate some degree of competition for ‘deposition sites’ between these two metals.

Carbon dioxide combining properties of the blood of the shore crab Carcinus maenas (L): carbon dioxide solubility coefficient and carbonic acid dissociation constants

1976 ◽  
Vol 64 (1) ◽  
pp. 45-57 ◽  
Author(s):  
J. P. Truchot
Keyword(s):  
Carbon Dioxide ◽  
Carbonic Acid ◽  
Sea Water ◽  
Dissociation Constants ◽  
Carcinus Maenas ◽  
Acid Dissociation ◽  
Shore Crab ◽  
Acid Dissociation Constants ◽  
Solubility Coefficient

The carbon dioxide solubility coefficient, alphaCO2, and the apparent carbonic acid dissociation constants, K'1 and K'2 were estimated in the serum of the crab Carcinus maenas at various temperatures and ionic strengths. At 15 degrees C, the indirectly determined alphaCO2 value is 0–0499 m-mole l-1 torr-1 for crabs living in normal sea water (salinity ca. 35 percent). It is apparently independent of the serum protein concentration and of the stage of the moulting cycle. For crabs living in undiluted sea water, the mean pK'1 value, determined either gasometrically or titrimetrically, is 6–027 at 15 degrees C. At the same temperature, pK'2=9-29. These values approximate to those of sea water at 35 percent salinity. pK'1 drops as temperature rises; the measured deltapK'1/deltat is −0-0053 pH unit degrees C-1 between 10 and 30 degrees C. PK'1 rises as the ionic strength is lowered. Alignment nomograms have been constructed for the determination of alphaCO2, pK'1 and pK'2 values in relation to various conditions of temperature and salinity.

scholarly journals Ionic Permeabilities of the Isolated Gill Cuticle of the Shore Crab Carcinus Maenas

1987 ◽  
Vol 131 (1) ◽  
pp. 159-174 ◽  
Author(s):  
J. M. LIGNON
Keyword(s):  
Sea Water ◽  
Carcinus Maenas ◽  
Shore Crab ◽  
Gill Lamella ◽  
Salt Solutions ◽  
Electrical Parameters ◽  
Selective Permeability ◽  
Cuticular Permeability ◽  
Ionic Exchanges

Electrical parameters of the cuticle of the posterior gill lamella of the shore crab Carcinus maenas, were measured. When the cuticle was perfused with crab saline (CS) inside and sea water (SW) outside, ionic replacements or dilutions of the bathing solutions produced changes in potential that showed a selective permeability to cations with respect to anions. Similar measurements made with the cuticle bathed in single salt solutions gave the following permeability sequence: NH4+> Rb+> Cs+> K+> Na+≊Ca2+ > Li+> Tris+> Mg2+ HCO3−> CH3COO−> Cl−> SO42-. From conductance measurements, the permeability of the cuticle to Ca2+ and Na+ was about 10−3cms−1. K+ and NH4+ were about five times more permeant, while Mg2+permeability was 5×10−5 cms−1. The permeability of the cuticle to anions lay between 10−6 and 10−5 cms−1. In addition, the cuticle showed an asymmetrical behaviour. These results suggest that the low anionic cuticular permeability can interfere with ionic exchanges across the whole gill. Note: Present address: Laboratoire d'Etude des Régulations Physiologiques, associé à l'Université Louis Pasteur, Centre National de la Recherche Scientifique, 23 rue Becquerel, 67087 Strasbourg, France.

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