The Regulation of Calcium and Magnesium in the Brackish Water Polychaete Nereis Diversicolor O.F.M

1970 ◽  
Vol 53 (2) ◽  
pp. 425-443
Author(s):  
C. R. FLETCHER
Keyword(s):  
Brackish Water ◽  
Calcium Concentration ◽  
Sea Water ◽  
Calcium Influx ◽  
Coelomic Fluid ◽  
Nereis Diversicolor ◽  
Active Uptake ◽  
Calcium And Magnesium ◽  
Electrochemical Potentials

1. Nereis diversicolor tolerates changes in the concentration of calcium and magnesium in its coelomic fluid proportional to the concentrations in the medium between chlorosities of 100-1000 mM/kg of water. 2. In lower salinities both ions are maintained relatively constant providing that the ratios of these ions to chloride in the medium are similar to the ratios in sea water. 3. The ratio of the concentration of calcium in the coelomic fluid to the concentration in the medium is a function of the salinity of the medium but not of the calcium concentration. 4. Both calcium and magnesium are at lower electrochemical potentials in the coelomic fluid than in the medium, indicating that it is not necessary to invoke active uptake. 5. The rate of calcium influx is substantial. 6. In salinities below to mM of chloride/kg of water the urine must contain less calcium than the coelomic fluid. 7. The significance of these results is discussed.

The regulation of haemolymph calcium concentration of the crab Carcinus maenas (L.)

1976 ◽  
Vol 64 (1) ◽  
pp. 149-157
Author(s):  
P. Greenaway
Keyword(s):  
Body Weight ◽  
Calcium Concentration ◽  
Calcium Uptake ◽  
Sea Water ◽  
Calcium Influx ◽  
Carcinus Maenas ◽  
Ionic Form ◽  
Calcium Balance ◽  
Active Calcium ◽  
The Difference

After acclimation, Carcinus can maintain calcium balance in dilute (35–100%) but not in low calcium sea water. 71% of total haemolymph calcium (9–54 +/− 0–42 mM) was in ionic form as compared with 90–9%(9–9mM) in sea water. On acclimation to dilute sea water the calcium activity of the haemolymph was greater than that of the medium, the difference being maintained by active calcium uptake. Carcinus is highly permeable to Ca2+, influx from sea water being 0–513 +/− 0–07 mumoles g-1 h-1 and the time constant for calcium influx 4-3 +/− 0–48 h. Calcium space represented ca. 25% wet body weight independent of body size or salinity of acclimation medium.

Hypo-Osmotic Urine in Nereis Diversicolor

1970 ◽  
Vol 53 (1) ◽  
pp. 101-108
Author(s):  
RALPH I. SMITH
Keyword(s):  
Baltic Sea ◽  
Sea Water ◽  
Coelomic Fluid ◽  
Osmotic Concentration ◽  
Nereis Diversicolor ◽  
Low Salinity

1. Nereis diversicolor, when regulating in water of low salinity, produces urine of lower osmotic concentration than the coelomic fluid. 2. The urine is significantly hypo-osmotic in 0.9-5.3 % sea water (Cl = 5-30 mM/l), and slightly hypo-osmotic in natural Baltic Sea water (17 % sea water; Cl = 95 mM/l). 3. The urine is probably iso-osmotic in 28 % sea water (Cl = 157 mM/l) and higher salinities.

Sodium and Chloride Balance in the Prawn, Palaemonetes Varians

1964 ◽  
Vol 41 (3) ◽  
pp. 591-601
Author(s):  
W. T. W. POTTS
Keyword(s):  
Water Balance ◽  
Brackish Water ◽  
Sea Water ◽  
Chloride Ions ◽  
Potential Difference ◽  
Sodium Balance ◽  
Sodium Ions ◽  
Active Sodium ◽  
Sodium Uptake ◽  
Active Uptake

1. The exchanges of sodium and bromide (for chloride) ions between the brackish-water prawn Palaemonetes varians and its environment are described. 2. In an isosmotic medium the exchange of sodium and chloride ions takes place by passive diffusion. 3. In full-strength sea water sodium ions are actively removed extrarenally, the potential difference produced by the active extrusion of sodium ions maintaining the chloride ions in passive equilibrium. There is some evidence of an increased flux of ions in hyperosmotic sea water associated with water-swallowing to obtain water for water balance. 4. In 2% sea water chloride ions are actively absorbed, the potential produced by this active uptake helping to maintain sodium balance; but some active sodium uptake also occurs. 5. In salinities below 2% uptake of ions declines and the animals can no longer maintain equilibrium.

The Effect of Calcium and Magnesium on Rabbit Blood Platelet Aggregation in Vitro

1964 ◽  
Vol 12 (01) ◽  
pp. 179-200 ◽  
Author(s):  
Torstein Hovig
Keyword(s):  
Platelet Aggregation ◽  
Cation Exchange ◽  
Calcium Concentration ◽  
Blood Platelets ◽  
Blood Platelet ◽  
Rabbit Blood ◽  
Calcium And Magnesium ◽  
Induced Aggregation ◽  
Blood Platelet Aggregation

SummaryThe effect of calcium and magnesium on the aggregation of rabbit blood platelets in vitro was studied, with the following results:1. Platelet aggregation induced by ADP or collagen could be prevented by EGTA or EDTA. The aggregating effect was restored by recalcification. The effect was also restored by addition of magnesium in EDTA-PRP, but not in EGTA-PRP unless a surplus of calcium was present.2. Calcium remained in concentrations of the order of 0.15–0.25 mM after dialysis or cation exchange of plasma. Aggregation of washed platelets resuspended in such plasma could not be produced with ADP or collagen, unless the calcium concentration was increased or that magnesium was added.3. The adhesiveness of blood platelets to collagen was reduced in EGTA-PRP and EDTA-PRP. Release of ADP from platelets influenced by collagen could not be demonstrated either in EGTA-PRP (presence of magnesium) or in EDTA-PRP.4. It is concluded that calcium is a necessary factor both for the reaction leading to release of ADP and for the the aggregation produced by ADP.5. Thrombin induced aggregation of washed platelets suspended in tris-buffered saline in the presence of calcium. No effect of magnesium could be observed unless small quantities of calcium were present.

Investigational Studies on Quantity of Salinity in Netravati River Estuary Sand-Coastal Karnataka

2018 ◽  
Vol 6 (6) ◽  
pp. 46
Author(s):  
Raveesha P ◽  
K. E. Prakash ◽  
B. T. Suresh Babu
Keyword(s):  
Brackish Water ◽  
Sea Water ◽  
Salt Water ◽  
Construction Material ◽  
Salt Content ◽  
River Estuary ◽  
Sand Sample ◽  
River Sand ◽  
Natural Aggregates

The salt water mixes with fresh water and forms brackish water. The brackish water contains some quantity of salt, but not equal to sea water. Salinity determines the geographic distribution of the number of marshes found in estuary. Hence salinity is a very important environmental factor in estuary system. Sand is one major natural aggregate, required in construction industry mainly for the manufacture of concrete. The availability of good river sand is reduced due to salinity. The quality of sand available from estuarine regions is adversely affected due to this reason. It is the responsibility of engineers to check the quality of sand and its strength parameters before using it for any construction purpose. Presence of salt content in natural aggregates or manufactured aggregates is the cause for corrosion in steel. In this study the amount of salinity present in estuary sand was determined. Three different methods were used to determine the salinity in different seasonal variations. The sand sample collected nearer to the sea was found to be high in salinity in all methods.  It can be concluded that care should be taken before we use estuary sand as a construction material due to the presence of salinity.

High environmental salinity induces memory enhancement and increases levels of brain angiotensin-like peptides in the crab Chasmagnathus granulatus

2000 ◽  
Vol 203 (22) ◽  
pp. 3369-3379 ◽  
Author(s):  
A. Delorenzi ◽  
B. Dimant ◽  
L. Frenkel ◽  
V.E. Nahmod ◽  
D.R. Nassel ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Brackish Water ◽  
Sea Water ◽  
Immunohistochemical Analysis ◽  
Facilitatory Effect ◽  
Long Term Memory ◽  
Stimulus Context ◽  
Memory Enhancement ◽  
Chasmagnathus Granulatus

Previous work on the brackish-water crab Chasmagnathus granulatus demonstrated that an endogenous peptide similar to angiotensin II plays a significant role in enhancing long-term memory that involves an association between context and an iterative danger stimulus (context-signal memory). The present results show that this memory enhancement could be produced by moving crabs from brackish water to sea water (33.0%) and keeping them there for at least 4 days. The possibility that such a facilitatory effect is due to osmotic stress is ruled out. Coincidentally, the level of angiotensin-II-like peptides in crab brain, measured by radioimmunoassay, increases with the length of exposure to sea water, reaching a significantly different level at the fourth day. The presence of angiotensin-II-like immunoreactive material in neural structures of the supraoesophageal and eyestalk ganglia was confirmed by immunohistochemical analysis. The results are interpreted as supporting the hypothesis that exposure to water of high salinity is an external cue triggering a process mediated by angiotensins that leads to enhanced memory in these crabs.

Selectivity and Response Characteristics of Human Olfactory Neurons

1997 ◽  
Vol 77 (3) ◽  
pp. 1606-1613 ◽  
Author(s):  
N. E. Rawson ◽  
G. Gomez ◽  
B. Cowart ◽  
J. G. Brand ◽  
L. D. Lowry ◽  
...  
Keyword(s):  
Calcium Concentration ◽  
Calcium Influx ◽  
Olfactory Neuron ◽  
Olfactory Neurons ◽  
Response Characteristics ◽  
Inositol 1,4,5 Trisphosphate ◽  
Transduction Mechanisms ◽  
Individual Odors ◽  
Second Messenger Pathways ◽  
Induced Changes

Rawson, N. E., G. Gomez, B. Cowart, J. G. Brand, L. D. Lowry, E. A. Pribitkin, and D. Restrepo. Selectivity and response characteristics of human olfactory neurons. J. Neurophysiol. 77: 1606–1613, 1997. Transduction mechanisms were investigated in human olfactory neurons by determining characteristics of odorant-induced changes in intracellular calcium concentration ([Ca2+]i). Olfactory neurons were freshly isolated from nasal biopsies, allowed to attach to coverslips, and loaded with the calcium-sensitive indicator fura-2. Changes in [Ca2+]i were studied in response to exposure to individual odors, or odorant mixtures composed to distinguish between transduction pathways mediated by adenosine 3′5′-monophosphate (cAMP; mix A) or inositol 1,4,5-trisphosphate (InsP3; mix B). Overall, 52% of biopsies produced one or more odorant-responsive olfactory neurons, whereas 24% of all olfactory neurons tested responded to odorant exposure with a change in [Ca2+]i. As in olfactory neurons from other species, the data suggest that odorant exposure elicited calcium influx via second-messenger pathways involving cAMP or InsP3. Unlike olfactory neurons from other species that have been tested, some human olfactory neurons responded to odorants with decreases in [Ca2+]i. Also in contrast with olfactory neurons from other species, human olfactory neurons were better able to discriminate between odorant mixtures in that no neuron responded to more than one type of odor or mixture. These results suggest the presence of a previously unreported type of olfactory transduction mechanism, and raise the possibility that coding of odor qualities in humans may be accomplished to some degree differently than in other vertebrates, with the olfactory neuron itself making a greater contribution to the discrimination process.

Depolarization modulates endothelial cell calcium influx and microvessel permeability

1991 ◽  
Vol 261 (4) ◽  
pp. H1246-H1254 ◽  
Author(s):  
P. He ◽  
F. E. Curry
Keyword(s):  
Membrane Potential ◽  
Calcium Concentration ◽  
Calcium Influx ◽  
Ringer Solution ◽  
Initial Increase ◽  
High Potassium ◽  
Microvessel Permeability ◽  
Microvessel Wall ◽  
Initial Peak ◽  
Peak Value

We investigated the mechanisms whereby high-potassium (57.9 mM) Ringer solutions attenuate the increase in permeability caused when microvessels are exposed to the calcium ionophores ionomycin and A23187 (5 microM). In single perfused microvessels we measured cytoplasmic calcium concentration, [Ca2+]i, in the cells forming the microvessel wall and the hydraulic conductivity, Lp, to follow changes in the permeability of the microvessel walls. In normal Ringer solution, [Ca2+]i was increased to an initial peak value of 226 +/- 12 nM after exposure to calcium ionophores; the corresponding increase in microvessel Lp was 10.3 +/- 2.6 times control. With high-potassium solutions, the peak value of [Ca2+]i was 133 +/- 12 nM and Lp was increased to only 2.5 +/- 0.7 times control. Increasing extracellular calcium from 1.1 to 5 mM with high potassium restored the initial peak value of [Ca2+]i to 303 +/- 38 nM. The increases in both [Ca2+]i and Lp were abolished in calcium-free solutions. If high-potassium solutions depolarize the cells forming the microvessel wall as indicated by the membrane potential-sensitive dye bisoxonol, then the magnitude of the initial increase in [Ca2+]i could be accounted for by changes in the electrochemical driving force through conductive channels for calcium ion. Our results conform to the hypothesis that the permeability properties of microvessels are modulated by changes in the membrane potential of the endothelial cells and/or pericytes forming the microvessel wall.

scholarly journals Extracellular accumulation of proline, serine and trehalose in the haemolymph of osmoconforming brackish-water mosquitoes

1987 ◽  
Vol 129 (1) ◽  
pp. 231-238 ◽  
Author(s):  
M. A. Garrett ◽  
T. J. Bradley
Keyword(s):  
Organic Compounds ◽  
Brackish Water ◽  
Sea Water ◽  
Full Range ◽  
Culex Tarsalis ◽  
Osmotic Concentration

Larvae of Culex tarsalis, a mosquito, are capable of surviving and developing in dilutions of sea water ranging from 0 mosmol l-1 to 700 mosmol l-1. In waters more dilute than 400 mosmol l-1, the larvae osmoregulate, whereas in those more concentrated than 400 mosmol l-1, the osmotic strength of the haemolymph parallels that of the medium, i.e. the larvae osmoconform. Over the full range of external concentrations tested, the larvae regulate the levels of Na+, K+, Mg2+, Ca2+ and Cl- in the haemolymph. Analyses of haemolymph samples from larvae adapted to media of 50 mosmol l-1 or 600 mosmol l-1 indicate that the increase in haemolymph osmotic concentration observed in media above 400 mosmol l-1 is due to the accumulation of organic compounds, particularly proline, serine and trehalose.

The accumulation of 137Cs by brackish water invertebrates and its relation to the regulation of potassium and sodium

1963 ◽  
Vol 43 (2) ◽  
pp. 541-565 ◽  
Author(s):  
G. W. Bryan
Keyword(s):  
New Media ◽  
Brackish Water ◽  
Sea Water ◽  
Indirect Evidence ◽  
The Body ◽  
Limiting Factor ◽  
Wide Range ◽  
Concentration Factors ◽  
The Relationship ◽  
Potamopyrgus Jenkinsi

The relationship between the ability of brackish water invertebrates to regulate Na and K and the extent to which the radioactive fission product 137Cs can be accumulated has been studied.The brackish water isopod Sphaeroma hookeri and the gastropod Potamopyrgus jenkinsi have been acclimatised to a wide range of sea-water dilutions. Unfed Sphaeroma can survive in sea-water concentrations of 100–2·5%, while Potamopyrgus can live fairly indefinitely in concentrations of 50–0·1%. Measurements of Na and K in the whole animals of both species and in the blood of Sphaeroma have been made. Salt movements are quite rapid and acclimatization to new media is achieved by both species in less than 10 h. Concentration factors for inactive K in particular increase to high values in the more dilute media.Uptake of the isotopes 42K and 137Cs from solution has been examined in both species over a range of sea-water concentrations. All of the body K is exchangeable with 42K and in Sphaeroma exchange of 42K between the blood and tissues is so rapid that the body surface appears to be the limiting factor in the uptake of the isotope. Both species exchange 42K more rapidly in the higher concentrations of sea water and one reason for this may be the existence of an exchange diffusion component of exchange which increases as the salinity of the medium is raised. Indirect evidence suggests that the excretion of 42K in urine is probably not an important factor in exchange.

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