Calcium Balance at the Postmoult Stage of the Freshwater Crayfish Austropotamobius Pallipes (Lereboullet)

1974 ◽  
Vol 61 (1) ◽  
pp. 35-45
Author(s):  
PETER GREENAWAY
Keyword(s):  
Calcium Uptake ◽  
Maximum Level ◽  
Freshwater Crayfish ◽  
Calcium Balance ◽  
Electrochemical Gradient ◽  
Uptake Mechanism ◽  
Austropotamobius Pallipes ◽  
Ionised Calcium ◽  
Net Uptake ◽  
Level 2

Net uptake of calcium by Austropotamobius begins 15-30 min after the moult and rapidly reaches a maximum level (2 µmoles/g/h at 10°C) which is maintained throughout stages A and B. At stage C1 the rate of net uptake falls sharply to a lower level which is gradually reduced until equilibrium is reached at C4. The uptake mechanism is near-saturated at 0.4 mM-Ca/l and half-saturated at 0.13 mM-Ca/l. In the absence of external HCO3- net uptake is reduced. Calcium uptake is against an electrochemical gradient. The concentration of ionised calcium in the haemolymph remains unchanged during the intermoult cycle.

Calcium Regulation in the Freshwater Crayfish Austropotamobius Pallipes (Lereboullet)

1972 ◽  
Vol 57 (2) ◽  
pp. 471-487
Author(s):  
PETET GREENAWAY
Keyword(s):  
Active Transport ◽  
Calcium Concentration ◽  
Calcium Uptake ◽  
Calcium Regulation ◽  
Freshwater Crayfish ◽  
Calcium Balance ◽  
Electrochemical Gradient ◽  
Austropotamobius Pallipes ◽  
Calcium Loss ◽  
Normal Calcium

1. Calcium regulation in normal and in calcium-depleted specimens of Austropotamobius pallipes in the intermoult condition has been investigated. 2. Calcium turnover was very low and the normal calcium balance was negative for much of the winter intermoult stage. 3. Calcium uptake was against a small electrochemical gradient, at least part of the influx occurring by active transport. 4. Most of the calcium loss occurred across the gills, and the urine contribution was small. 5. Calcium-depleted animals showed only a small fall in haemolymph calcium concentration and calcium uptake was not significantly increased by depletion.

Calcium Balance at the Premoult Stage of the Freshwater Crayfish Austropotamobius Pallipes (Lereboullet)

1974 ◽  
Vol 61 (1) ◽  
pp. 27-34
Author(s):  
PETER GREENAWAY
Keyword(s):  
Body Surface ◽  
The Body ◽  
Ionized Calcium ◽  
Freshwater Crayfish ◽  
Calcium Balance ◽  
Electrochemical Gradient ◽  
Austropotamobius Pallipes

The premoult stage in Austropotamobius pallipes is characterized by a net loss of calcium which increases from D0 to a maximum of 0.83 µmoles/g/h at D4. The concentration of ionized calcium in the haemolymph does not increase during the premoult stage although there is an increase in complexed calcium. The electrochemical gradient across the body surface is similar to that at the intermoult stage and favours calcium outflux. Possible routes for calcium net loss have been discussed and a mechanism for elimination of calcium has been proposed.

scholarly journals Calcium Regulation in the Freshwater Mollusc, Limnaea Stagnalis (L.) (Gastropoda: Pulmonata)

1971 ◽  
Vol 54 (1) ◽  
pp. 199-214 ◽  
Author(s):  
PETER GREENAWAY
Keyword(s):  
Calcium Concentration ◽  
Calcium Regulation ◽  
Calcium Balance ◽  
Calcium Depletion ◽  
Uptake Mechanism ◽  
Freshwater Mollusc ◽  
Net Uptake ◽  
Limnaea Stagnalis ◽  
Sodium Regulation ◽  
Linear Manner

1. Calcium regulation in normal and calcium-depleted snails has been investigated. 2. L. stagnalis has an uptake mechanism with a high affinity for calcium ions and shows a positive calcium balance in media containing more than 0.062 mM Ca/l. 3. Influx and net uptake of calcium are related to external calcium concentration in a non-linear manner. The uptake mechanism is half-saturated and near-saturated in external media containing 0.3 and 1.0-1.5 mM Ca/l respectively. 4. Calcium uptake from external concentrations of less than 0.5 mM Ca/l is against a small electrochemical gradient whereas from external concentrations greater than 0.5 mM Ca/l there is no adverse gradient. 5. Calcium depletion does not significantly alter the normal influx or net uptake rate of calcium from 1.0 mM Ca/l. 6. The calcium concentration in the blood remains constant during net uptake from, and net loss to, the medium. 7. A comparison is made between the mechanisms of sodium regulation and calcium regulation in L. stagnalis.

Expression patterns of two carbonic anhydrase genes, Na+/K+-ATPase and V-type H+-ATPase, in the freshwater crayfish, Cherax quadricarinatus, exposed to low pH and high pH

2017 ◽  
Vol 65 (1) ◽  
pp. 50 ◽  
Author(s):  
Muhammad Yousuf Ali ◽  
Ana Pavasovic ◽  
Peter B. Mather ◽  
Peter J. Prentis
Keyword(s):  
Carbonic Anhydrase ◽  
Expression Patterns ◽  
Maximum Level ◽  
Low Ph ◽  
Freshwater Crayfish ◽  
Α Subunit ◽  
Cherax Quadricarinatus ◽  
High Ph ◽  
Internal Ph ◽  
Ph Conditions

Carbonic anhydrase (CA), Na+/K+-ATPase (NKA) and Vacuolar-type H+-ATPase (HAT) play vital roles in osmoregulation and pH balance in decapod crustaceans. As variable pH levels have a significant impact on the physiology of crustaceans, it is crucial to understand the mechanisms by which an animal maintains its internal pH. We examined expression patterns of cytoplasmic (CAc) and membrane-associated form (CAg) of CA, NKA α subunit and HAT subunit a in gills of freshwater crayfish, Cherax quadricarinatus, at three pH levels – 6.2, 7.2 (control) and 8.2 – over 24 h. Expression levels of CAc were significantly increased at low pH and decreased at high pH conditions 24 h after transfer. Expression increased at low pH after 12 h, and reached its maximum level by 24 h. CAg showed a significant increase in expression at 6 h after transfer at low pH. Expression of NKA significantly increased at 6 h after transfer to pH 6.2 and remained elevated for up to 24 h. Expression for HAT and NKA showed similar patterns, where expression significantly increased 6 h after transfer to low pH and remained significantly elevated throughout the experiment. Overall, CAc, CAg, NKA and HAT gene expression is induced at low pH conditions in freshwater crayfish.

Characterization of branchial transepithelial calcium fluxes in freshwater trout, Salmo gairdneri

1988 ◽  
Vol 254 (3) ◽  
pp. R491-R498 ◽  
Author(s):  
S. F. Perry ◽  
G. Flik
Keyword(s):  
Active Transport ◽  
Calcium Uptake ◽  
Chloride Cells ◽  
Salmo Gairdneri ◽  
Apical Surface ◽  
Electrochemical Gradient ◽  
Plasma Membrane Vesicles ◽  
Pavement Cells ◽  
Calcium Fluxes

Experiments were performed to determine whether gill transepithelial calcium fluxes in the freshwater trout (Salmo gairdneri) are passive or require active transport and to characterize the mechanisms involved. A comparison of the in vivo unidirectional flux ratios with the flux ratios calculated according to the transepithelial electrochemical gradients revealed that calcium uptake from the water requires active transport of Ca2+. The inhibition of calcium uptake by external lanthanum, the specific deposition of lanthanum on the apical surface of chloride cells, and the favorable electrochemical gradient for calcium across the apical membrane suggest that the initial step in branchial calcium uptake is the passive entry of calcium into the cytosol of chloride cells through apical channels that are permeable to calcium. The study of gill basolateral plasma membrane vesicles demonstrated the existence of a high-affinity calmodulin-dependent calcium-transporting system [half-maximal Ca2+ concentration (K0.5) = 160 nM, Vmax = 1.86 nmol.min-1.mg protein-1]. This system actively transports calcium from the cytosol of chloride cells into the plasma against a sizeable electrochemical gradient, thereby completing the transepithelial uptake of calcium. Calcium efflux occurs passively through paracellular pathways between chloride cells and adjacent pavement cells or between neighboring pavement cells.

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.

Regulation of calcium balance in the sturgeon Acipenser naccarii: a role for PTHrP

2007 ◽  
Vol 293 (2) ◽  
pp. R884-R893 ◽  
Author(s):  
Juan Fuentes ◽  
Christophe Haond ◽  
Pedro M. Guerreiro ◽  
Nádia Silva ◽  
Deborah M. Power ◽  
...  
Keyword(s):  
Calcium Transport ◽  
Calcium Uptake ◽  
Dietary Calcium ◽  
Calcium Deficiency ◽  
Cell Number ◽  
The Body ◽  
Whole Body ◽  
Calcium Balance ◽  
Parathyroid Hormone Related Protein ◽  
Juvenile Sturgeon

Calcium regulation in sturgeon is of special interest because they are a representative of the ancient fishes possessing mainly cartilaginous skeletons and a supposedly low calcium demand. The present study aimed to characterize the effect of a chronic absence of dietary calcium and the effect of parathyroid hormone-related protein (PTHrPA) (1-34) ( 7 ) on calcium balance in juvenile sturgeon ( Acipenser naccarii). At rest, sturgeon juveniles are in net positive calcium balance, since whole body calcium uptake is significantly higher than efflux and calcium accumulates in the body. To study the importance of dietary calcium, the sturgeon were kept on a calcium-free diet for 8 wk. This manipulation impaired growth as measured by failure to gain weight or increase in length and indicates that dietary calcium is important for growth in sturgeon. An increased whole body calcium uptake partially compensated dietary calcium deficiency and was associated with increased gill chloride cell number in lamellae and filaments in parallel with increased gill Na+K+-ATPase activity. In addition, a single injection of piscine PTHrP(1-34) significantly increased whole body calcium uptake and decreased whole body calcium efflux. Administration of PTHrP significantly increased circulating plasma calcium 4–24 h postinjection. The increase in net calcium transport and increased plasma levels of calcium is consistent with the actions of a hypercalcemic factor. It would appear that the sturgeon rely on calcium for growth and tightly regulate calcium transport. The action in calcium balance is consistent with PTHrP acting as a hypercalcemic factor in sturgeon.

Calcium Uptake in Rat Parotid Gland Secretory Granules

1991 ◽  
Vol 70 (12) ◽  
pp. 1524-1527 ◽  
Author(s):  
J.E. Porter ◽  
P. Cheung ◽  
F.J. Dowd
Keyword(s):  
Parotid Gland ◽  
Calcium Uptake ◽  
Secretory Granules ◽  
Uptake Mechanism ◽  
Atpase Inhibitors ◽  
Rat Parotid Gland ◽  
Disulphonic Acid ◽  
Rat Parotid ◽  
Hydrolysis Of ◽  
Isolated Rat

45Ca2+ uptake in isolated rat parotid secretory granules was examined in the presence of oxalate. Uptake of calcium was dependent on time, with the maximum occurring at 15 min. The uptake of calcium was dependent on adenosine-5'-triphosphate (ATP), and substitution of ATP with B,g-methylene-ATP did not stimulate calcium uptake. Enzyme marker analysis indicated that mitochondria accounted for no greater than 3.0 ±0.2% of the observed ATP-dependent calcium uptake. Calcium uptake was blocked by the ATPase inhibitors tributyltin, IC 50 = 12.2 ±0.6 nmol/L and 4-acetamido-4'-isothiocyano-2,2'-stilbene disulphonic acid (SITS), IC50 = 3.0 ±0.3 (μmol/L. These results indicate that in the parotid secretory granule there is a calcium uptake mechanism that is dependent on the hydrolysis of ATP and is suppressed by two inhibitors of granule ATPase.

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