Calcium concentration in tomato fruits in relation to the incidence of blossom-end rot

1971 ◽  
Vol 11 (52) ◽  
pp. 570 ◽  
Author(s):  
CR Millikan ◽  
EN Bjarnason ◽  
RK Osborn ◽  
BC Hanger
Keyword(s):  
Concentration Ratio ◽  
Calcium Concentration ◽  
Calcium Treatment ◽  
Tomato Fruits ◽  
Low Calcium ◽  
Blossom End Rot ◽  
Calcium And Magnesium ◽  
Nutrient Solutions ◽  
Sand Cultures

Tomato fruits (CV. Grosse Lisse) were grown in sand cultures irrigated with nutrient solutions containing either normal- (120-160 p.p.m. Ca) or low-calcium (40 p.p.m. Ca) levels. Data were collected from the first five trusses, and restricted to fruits arising from the first three flowers of each truss. A greater yield of fruit and fewer fruit affected by blossom-end rot (BER) were produced by the normal than the low calcium treatment. Irrespective of treatment or BER incidence, the calcium concentration was higher in the stem end than the calyx end, and the concentrations of calcium and potassium were greater in trusses 1 and 2 than 4 and 5. BER affected the largest fruit in the normal, but the smallest in the low calcium treatment. Within the same trusses affected fruit had a lower calcium concentration in the stem end than did healthy fruit. For all fruits the ranges in calcium percentage (on dry basis) recorded were : Healthy fruits-stem end 0.086-0.029, calyx end 0.057-0.018 ; affected fruits-stem end 0.072-0.022, calyx end 0.045-0.020. Differences in magnesium and potassium concentrations in stem or calyx ends between healthy and affected fruits were recorded. The K: Ca ratio was higher in affected fruits, but the incidence of BER was unrelated to the Mg : Ca ratio. For both calcium and magnesium the stem end : calyx end concentration ratio was lower in affected than healthy fruit.

Effect of calcium, pH and nitrogen on the growth and chemical composition of some tropical and temperate pasture legumes. II.* Chemical composition (calcium, nitrogen, potassium, magnesium, sodium and phosphorus)

1976 ◽  
Vol 27 (5) ◽  
pp. 625 ◽  
Author(s):  
CS Andrew ◽  
AD Johnson
Keyword(s):  
Chemical Composition ◽  
Dry Matter ◽  
Calcium Concentration ◽  
Dry Matter Production ◽  
Magnesium Concentration ◽  
Sand Culture ◽  
Calcium Treatment ◽  
Pasture Legumes ◽  
Low Calcium ◽  
Matter Production

The chemical composition of tops and roots of nodulated and non-nodulated plants of some tropical and temperate pasture legumes grown in sand culture is reported and discussed in relation to nodulation efficiency and dry matter production, and nutrient interaction. In most species, increasing pH raised the nitrogen concentrations in the tops of nodulated plants; calcium treatment had little effect. Increasing the calcium concentration of the nutrient solution from 0.125 to 2.0 mM markedly increased the calcium~ concentration in the tops of all species, but in the roots to only a minor extent. Concentrations in tops differed between species. Concentrations in the tops of modulated plants were increased as a result of increasing pH, particularly at the low calcium treatment and for those species sensitive to low pH (Glycine wightii, Medicago species). Increasing the calcium concentration lowered the magnesium concentration, but the total cation content was not significantly affected. In the tropical species, phosphorus concentrations in the tops were increased by reducing pH at both calcium treatments; values were higher at the low calcium treatment than at the high calcium treatment. Roots accumulated inore phosphorus than the tops. Differences in the response of the species cannot be directly related to their mineral composition. With respect to nodulation and dry matter production, it is considered that the pH is the dominant factor and operates in the nodule initiation phase and in subsequent nitrogen production. _______________ *Part I, Aust. J. Agric. Res., 27: 611 (1976).

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.

scholarly journals Secretion and degradation of parathormone as a function of intracellular maturation of hormone pools

1979 ◽  
Vol 83 (3) ◽  
pp. 521-528 ◽  
Author(s):  
JJ Morrissey ◽  
DV Cohn
Keyword(s):  
Cyclic Amp ◽  
Half Life ◽  
Calcium Concentration ◽  
Hormone Secretion ◽  
Ionized Calcium ◽  
Dibutyryl Cyclic Amp ◽  
Low Calcium ◽  
High Calcium ◽  
Parathormone Secretion

The biosynthesis, processing, and secretion of parthormone and the effect of calcium on these processes were measured in dispersed porcine parthyroid cells incubated with [(35)S]methionine. Proparathormone was detected at 10 min, the earliest time measured, and was rapidly and apparently quantitatively converted to parathormone. The half-life of the prohomormone pool was 15 min. Secretion of parathormone was detected by 20 min. In pulse-chase experiments there was a period between 20 and 40 min during which the wave of newly-synthesized parathormone was secreted. After 40 min during little additional radioactive hormone was secreted, but dibutyryl cyclic AMP, an agent that can mobilize stored parathormone, when added to the incubation mixtures enhanced radioactive parathormone secretion but only after 60 min, although it increased net hormone secretion as determined by radioimmunoassay to the same extent at all times studied. When the ionized calcium concentration of the medium was lowered, more radioactive hormone was secreted at all times but the effect was greatest on that hormone that was synthesized less than 60 min previously ; however, net hormone secretion in contrast to radioactive hormone was enhanced equally at all intervals. These data could mean that the refractoriness to secretion of parathormone 40-60 min of age was related to maturation of secretory container preparatory to storage. Low calcium (0.5 mM) stimulated hormone secretion up to fivefold compared to high calcium (3.0 mM) but did not affect synthesis of parathormone or proparathormne or conversion of the latter to hormone. During processing at least 70 percent of the intracellular parathormone was lost, presumably through proteolysis and this degradation was greater at high calcium. These data have been interpreted in light of the concept that two secretable pools of parathormone exist within the parathyroid.

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.

scholarly journals Magnesium modulates parathyroid hormone secretion and upregulates parathyroid receptor expression at moderately low calcium concentration

2013 ◽  
Vol 29 (2) ◽  
pp. 282-289 ◽  
Author(s):  
M. E. Rodriguez-Ortiz ◽  
A. Canalejo ◽  
C. Herencia ◽  
J. M. Martinez-Moreno ◽  
A. Peralta-Ramirez ◽  
...  
Keyword(s):  
Parathyroid Hormone ◽  
Calcium Concentration ◽  
Hormone Secretion ◽  
Receptor Expression ◽  
Low Calcium

Stimulation of renin release in perfused kidney by low calcium and high magnesium

1977 ◽  
Vol 232 (4) ◽  
pp. F377-F382 ◽  
Author(s):  
J. S. Fray
Keyword(s):  
Sodium Excretion ◽  
Calcium Concentration ◽  
Perfusion Pressure ◽  
Rat Kidney ◽  
Sodium Concentration ◽  
Renin Release ◽  
Isolated Perfused Rat Kidney ◽  
Low Calcium ◽  
Perfused Rat Kidney ◽  
Stimulation Of

These experiments were designed to test whether changing perfusate calcium or magnesium concentrations affected renin release in the isolated perfused rat kidney, and whether kidneys removed from sodium-loaded or sodium-deprived rats released the same amount of renin in response to identical stimuli. Kidneys were perfused with Kreb-Henseleit solution containing albumin. Renin release was inversely related to perfusate calcium concentration, whereas renin release was directly related to perfusate magnesium. Although a low calcium medium or low perfusion pressure (50 mmHg) stimulated renin release, the release was substantially greater in the sodium-deprived rats. Increasing the perfusate sodium concentration from 85 to 206 mM increased excretion, but did not alter renin release. It is concluded that a) low perfusate calcium and high magnesium concentrations stimulate renin release, b) kidneys removed from sodium-deprived rats released substantially more renin thatn those from sodium-loaded rats, and c) changing perfusate sodium concentration alters sodium excretion, but does not affect renin release.

The amount and distribution of calcium in the exoskeleton of intermoult crayfish of the genera Engaeus and Geocharax

1976 ◽  
Vol 27 (3) ◽  
pp. 517 ◽  
Author(s):  
BJ Mills ◽  
P Suter ◽  
PS Lake
Keyword(s):  
Calcium Concentration ◽  
Habitat Requirements ◽  
Total Calcium ◽  
Constant Concentration ◽  
Calcium Distribution ◽  
Low Calcium ◽  
Decapod Crustacea ◽  
Crayfish Species

Total calcium concentration and calcium distribution have been studied in the exoskeletons of the crayfish Engaeus fossor, E. leptorhynchus, Engaeus sp, and Geocharax falcata. In all species the total exoskeleton calcium concentration is low in comparison with most other crustaceans, especially the decapod Crustacea. Furthermore the results suggest that the total exoskeletal calcium concentrations of two of the species (E. fossor and Engaeus sp.) decreases with increased crayfish size whilst one other species studied (G. falcata) maintains a constant concentration of calcium with increased crayfish size. It is suggested that reduction in (relative) calcification is an adaptation to the low calcium concentrations in the waters inhabited by the crayfish. The distribution of exoskeletal calcium in the crayfish species studied was dissimilar. The significance of these differences in calcium distribution is discussed in relation to the habitat requirements of each species.

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