Magnesium and strontium compositions of Recent benthic foraminifera from the Coral Sea, Australia and Prydz Bay, Antarctica

Analyses of the Mg/Ca and Sr/Ca ratios of the modern benthic foraminifera, Cibicides wuellerstorfi (epifaunal) and Uvigerina species (infaunal) from the Coral Sea, and Cibicides refulgens (epifaunal) and Trifarina angulosa (infaunal) from Prydz Bay, Antarctica revealed relationships with temperature that have possible applications for reconstructions of bottom-water paleotemperatures. A positive relationship exists between the Mg/Ca and Sr/Ca ratios of Cibicides wuellerstorfi and Cibicides refulgens and ambient temperatures, at least within the range of 2 and 6°C. For the correlation between Mg/Ca compositions and temperature the r² values range from 0.78 (C. wuellerstorfi alone) to 0.88 (C. wuellerstorfi and C. refulgens together). At present, the Mg/Ca-temperature relationship must be regarded as tentative because of significant overlap of standard error values. The relationship between the Sr/Ca compositions of C. wuellerstorfi and bottom-water temperature yields an r² value of 0.95. These results indicate that Sr/Ca and possibly Mg/Ca ratios of Cibicides wuellerstorfi may provide useful information for the assessment of paleotemperature. Single-species data are presently insufficient to assess the influence of ambient temperature on trace-element compositions of Uvigerina species. Trifarina angulosa may have Mg/Ca compositions which are positively related to temperature, but Sr/Ca values seem unaffected by temperature. This may be due to pore-water influences on infaunal tests or to vital effects. Although more modern data are needed, our present results suggest that Sr/Ca ratios and possibly Mg/Ca ratios of some benthic foraminifera have the potential to be useful paleothermometers, at least within a temperature range of −2 to 6°C.     

Electron probe analysis of strontium in mussel (Bivalvia,Mytilidae) shells: Feasibility of estimating water temperature

Electron microprobe step-scan analyses across the inner nacreous layer of a sectionedMytilus edulis shell revealed no long-term periodic (e.g., seasonal) variation in the concentration of strontium. Similarly, no significant difference was found between a specimen sampled in February (water temperature = 1.3 °C) and one sampled in August (water temperature = 18.0 °C) with regard to the concentration of strontium within the most recently deposited aragonite. Correlation of the amount of strontium within various nacreous regions of the shells of living or fossil mytilids with water temperatures (present or past) is probably not possible through the use of an electron probe, at least to the extent that strontium variation within the nacre ofMytilus edulis is representative of that in nacreous layers of all mytilids.     

Tissues and organs as indicators of intestinal absorption of minerals and trace elements,evaluated in rats

Tissue and organ deposition and blood parameters were evaluated as indices of mineral and trace element absorption in rats. The absorption of elements was quantified in relation to nitrogen retention, i.e., considering the weight gain and new tissue synthesis. A rapeseed meal diet was supplied with three levels of calcium, two levels of zinc, and two levels of copper in a factorial design. In general, an increase in dietary mineral content increased the relative absorption, which in turn, increased the tissue deposition progressively. Striated muscle, however, did not respond to either an increased calcium or zinc supply. Furthermore, an increased calcium absorption caused a depression of the fractional phosphorus and magnesium content of femur bones. The copper content of the kidneys and the heart muscle was directly proportional to the amount of absorbed zinc and iron, respectively. The iron content of tissues was, in general, inversely proportional to zinc absorption and showed a tendency to be directly proportional to copper absorption. The zinc level in tissues was, in a similar way, inversely correlated to measured calcium absorption. In conclusion, interactions between elements do not only affect the intestinal element absorption, but also the distribution of already absorbed elements in tissues and organs.     

Dinoflagellate cysts as indicators of water quality and productivity in British Columbia estuarine environments

Palynological analyses of 60 surface sediment samples from estuarine environments near Vancouver Island, including the Georgia Strait (GS), the Effingham (EFF) and the Seymour–Belize (SB) Inlets were performed in order to document the distribution of dinoflagellate cyst assemblages and their relationship to hydrographic conditions, productivity and nutrient concentrations. We tested transfer functions using the analogue method, and suggest that dinoflagellate cyst assemblages can be used to reconstruct primary productivity, temperature and salinity. The EFF and SB Inlets are characterized by a dominance of autotrophic taxa, particularly Operculodinium centrocarpum, whereas the Protoperidinioid and gymnodinial heterotrophic taxa such as Quinquecuspis concreta and Brigantedinium spp. dominate the assemblages of the GS. Multivariate analysis shows that this distribution is closely linked to primary productivity, sea-surface temperature (SST) and spring silica concentration. The abundance of autotrophic taxa in the EFF and SB Inlets is associated with high primary productivity and low summer SST, indicating summer upwelling of coastal British Columbia, whereas the heterotrophic taxa that characterizes the GS assemblages are related to low productivity, high summer SST and high silica concentration during spring. Multivariate analysis shows that the most important environmental parameters related to dinocyst distribution in the restricted embayment of the GS, are distance to the shore, distance to Vancouver Harbor, spring sea surface salinity (SSS), spring phosphate concentration and spring productivity. The autotrophic taxa are generally more common in coastal and shallow waters, but Spiniferites ramosus and Pentapharsodinium dalei show an opposite correlation to spring productivity and salinity. P. dalei is particularly abundant around Vancouver Harbor, near highly urbanized shores and within the Fraser River plume, where salinity is low and spring productivity and continental runoff are high. S. ramosus shows its highest abundance on the western coast of GS. Protoperidinioid and gymnodinial cysts characterize distal zones within the central and southern GS that are associated with a mixture of brackish waters coming from the Fraser River and deep upwelling waters entering the GS via Juan de Fuca Strait. The relationship between dinoflagellate cyst assemblages and primary productivity in these estuarine systems differs from that in oceanic and outer neritic zones, where the abundance of heterotrophic taxa is commonly associated with upwelling and high productivity.     

Magnesium and sulphur in the calcite shells of two brachiopods, Terebratulina retusa and Novocrania anomala

This study determines the distribution of magnesium and sulphur in the shells of two species of brachiopod from the same environment to highlight environmental and biological influences on shell composition. In Terebratulina retusa there are differences in magnesium concentration between the primary layer and the outer and inner regions of the secondary layer. In contrast, Novocrania anomala has a shell composed of high magnesium calcite and there is no significant difference in magnesium concentration between the primary and the secondary shell layers. Sulphur provides an indication of the distribution of sulphated organic matrix within the shells of T. retusa and N. anomala . In T. retusa the distribution of magnesium and sulphur correlates across the shell; however, there is no evidence for a relationship between magnesium and sulphur distribution in N. anomala . The relationship between magnesium and sulphur in T. retusa indicates that a proportion of the magnesium content of the shell is associated with the sulphated fraction of the organic matrix. In these two species of brachiopod, from the same environment, magnesium and organic concentration and distribution are very different, emphasizing the importance of fully understanding the factors that control biomineral composition before the application of these biominerals to environmental studies.     

Concentations of copper, Zinc, and magnesium in sera from patients with idiopathic dilated cardiomyopathy

Trace elements are known to have a key role in myocardial metabolism. The accumulation (cobalt, arsenic, copper) or deficiency (selenium, zinc) of trace elements may be responsible for idiopathic dilated cardiomyopathy. We investigated the trace element concentrations (Cu, Zn, Mg) in sera from patients with dilated cardiomyopathy by atomic absorption spectrophotometry. We observed that patients with dilated cardiomyopathies have higher copper and lower zinc concentrations in serum than healthy controls. The magnesium concentrations of patients did not differ significantly from that of control subjects.     

Coupling of strontium and calcium cycles in Lake Constance

The contents of Sr and Ca were measured weekly in Lake Constance in 1986. Epilimnetic concentrations of Ca changed between 1.30 × 10^-3 mol l^-1 (during homothermy) and 0.9 × 10 -3 mol l^-1 (during thermal stratification). The seasonal fluctuations of Ca were correlated with those of Sr (between 4.61 and 5.36 mol l^-1). The epilimnion was permanently oversaturated with respect to calcite but not with respect to SrCO₃. Analysis of the settling process by use of sedimentation traps revealed two short episodes of very high authigenic settling fluxes of CaCO₃, triggered by phytoplankton diatoms. Seasonal changes of the Ca contents (between 4.1 and 30.7 percent of the dry weight) and of the Sr concentrations (from 12 to 75 × 10^-3 percent) in the settling material were closely correlated. This suggests a coprecipitation mechanism with a nearly constant stoichiometry of (atoms Sr/atoms Ca) × 1000 of 0.84. Coprecipitation of Sr or Ca with organic matter was insignificant. In the hypolimnion some Sr and Ca were released from the settling material. These results strongly suggest that the cycle of Sr in Lake Constance is driven predominantly by coprecipitation with calcite. The principal chemical mechanisms leading to coprecipitation are discussed.     

The physical-chemical limnology of a desert reservoir

The physical-chemical limnology of a desert lake in central Arizona was investigated from February 1971–July 1973. The reservoir was found to be a warm-monomictic, eutrophic lake which exhibited pronounced thermal stratification during the summer months. Surface water temperatures ranged from a minimum of ca. 9 C in January to a maximum near 30 C in July–August. Chemically the lake may be described as a hard water lake of moderately high alkalinity and salinity. The concentration of the principal ions was affected significantly by precipitation run-off. The primary nutrients N and P were subject to considerable seasonal variability, being influenced most by precipitation and phytoplankton abundance. Trace element concentrations were low and showed comparatively little fluctuation during the study.     

Respiration of midges (Diptera; Chironomidae) in British Columbian lakes: oxy-regulation, temperature and their role as palaeo-indicators

1. The specific respiration rate of 13 chironomid taxa and Chaoborus were measured to test the hypothesis of the relation between a species' ability to regulate their oxygen uptake and their distributional patterns among nine study lakes in British Columbia, Canada.
2. Respiration patterns of individual taxa were modelled using piecewise linear regression with break point and simple hyperbolic functions. Three types of respiration curves were identified: (i) classical oxy-conformers (e.g. littoral Cricotopus ) which cannot sustain a sufficient oxygen uptake with decreasing oxygen availability; (ii) oxy-regulators (e.g. profundal Chironomus ) which can regulate and maintain a constant respiration until a certain critical point and (iii) oxy-stressors ( Micropsectra ) which increase their respiration rate with decreasing oxygen availability until a critical point.
3. Respiration was measured at two different temperatures (10 and 20 °C), and over the range of oxygen saturation conditions studied here (0–90%) mean Q ₁₀ values varied from 1.3 to 2.5.
4. The results show that different chironomid taxa have varying sensitivity to low oxygen concentrations and different respiratory responses to increased temperature. The critical point increased to higher oxygen saturation for six taxa, decreased for one taxon and was unchanged for two taxa.
5. The results illustrate one of the possible biological mechanisms behind the use of chironomids as temperature and climate indicators in palaeoecological studies by exploring the link between temperature and respiration physiology.     

Temperature effects on the incorporation of strontium in otolith of Japanese eel Anguilla japonica

The effects of temperature on somatic and otolith growth and the incorporation of strontium in otolith of the Japanese eel, were studied in laboratory-reared and field-caught eels. The somatic and otolith growth rates of the eel increased significantly with temperature and were estimated as approximately 0·096 mm t.l, (P<0·01) and 0·36 μm in otolith diameter per degree-day (0·01相似文献   

In vitro influence of zinc and magnesium on the deformability of red blood cells artificially hardened by heating

Trace elements have been shown to improve red blood cell (RBC) deformability: zinc in sickle cell disease and magnesium in an in vitro model of chemically rigidified erythrocytes. In this study, we investigated the effect and the influence of incubation time of zinc or magnesium on an in vitro model of rigidified RBCs by heating. Erythrocyte rigidity was determined by viscosimetry at high shear rate by a falling ball viscosimeter MT 90. In the first part of the study, six normal volunteers participated. Viscosimetry was performed on native blood before and after heating the sample for 10 min at 50°C. Therefore, increasing concentrations of zinc gluconate (final concentration: 0.5–4 g/L) or isotonic NaCl as control medium were added to the sample. Heating induced a twofold increase in all indices of RBC rigidity (p<0.05). At all these concentrations of zinc, a highly significant, dose-related fluidifying effect was observed (40–70%): this effect was immediately obtained and did not change over 60 min. Even at the highest concentration, recovery was not complete. In the second part of the study, we studied magnesium’s effects on blood. In a first protocol, whole blood was rigidified by heating at 56°C for 10 min, and the correcting effect of 5 min of incubation at 37°C of RBCs in 150 mmol/L NaCl, MgSO₄, magnesium acetate, and magnesium gluconate was investigated. In a second protocol, the same incubation with NaCl and magnesium salts was made on blood that had not been previously heated. In a third protocol, the correcting effect of magnesium gluconate on heated red blood cells was tested at four concentrations (75, 150, 225, and 300 mmol/L) over 1 h, for evaluating the effects of both concentration and time. Erythrocyte rigidity by heating is corrected by the three salts employed in protocol 1 (compared to sodium). In protocol 2, the deformability of normal (nonheated) red cells is not modified by magnesium. In protocol 3, no marked modification over 1 h is observed. The correcting effect is not complete for 75 mmol/L Mg, but remains the same at the three other concentrations. This study shows that zinc and magnesium at supraphysiological concentration are able to reverse RBC’s rigidification induced by heating, but that magnesium does not modify the flexibility of normal RBCs. This article suggests that zinc and magnesium may be studied in vivo as potential pharmacologic tools for improving hemorheologic disturbances.     

Desert perennials as plant and soil indicators in Eastern Arabia

Soils of different Eastern Arabian vegetation types, dominated by five desert perennials have been analysed for their texture, salinity and surface hardness. The vegetation types were analysed for plant species richness and composition. Special emphasis was given to Abu Dhabi's widespread terrestrial perennials Cyperus conglomeratus Rottb., Haloxylon salicornicum (Moq.) Bge., Pennisetum divisum (Gmel.) Henr., Seidlitzia rosmarinus Ehrenb. ex Bge. and Zygophyllum mandavillei Hadidi. The results show some important relationships between soils and plants. C. conglomeratus indicates the lowest soil salinity levels and the finest texture. P. divisum indicates the highest species richness and S. rosmarinus indicates the lowest species richness. Z. mandavillei indicates the highest salinity levels, the largest soil particle size, and the hardest soil surfaces.     

Seasonal and physiological variations in serum chemistry and mineral concentrations in cattle

The present study reports the seasonal and physiological variations of copper, zinc, magnesium, iron sodium chlorine, potassium, calcium, phosphorus, urea, alkaline phosphatase (ALP), creatinine (CR), aspartate aminotransfrase (AST), alanine aminotransferase (ALT), cholesterol, albumin, globulin, lactate dehydrogenase (LDH), and total protein concentrations in cattle. Two groups of mated (n=14) and nonmated (n=10), healthy cows were selected for the study. Serum samples were collected at each of four periods: (1) early pregnancy (May), (2) midpregnancy (August), (3) late pregnancy (October), and (4) lactation (February). Physiological variations result in changes of cholesterol, calcium, LDH, and total protein concentrations. Phosphorus varies only with seasonal but not physiological changes, whereas ALP, copper, magnesium, and potassium concentrations change with physiological and seasonal conditions. The copper concentration is increased through the pregnancy. Neither the seasonal nor the physiologic variations affect zinc, iron, sodium, chlorine, calcium, urea, creatinine, albumin, and globulin values in both groups in all periods. Thus, these values can be used as reference for both mater and nonmated bovines. The measured total protein might not reflect its true value because of dehydration during the hot season. These observations suggest that seasonal and physiologic variations have to be taken into consideration for the correct interpretation of serum chemistry and elements status in cattle. Nutritional supplements are required for cattle during certain periods to avoid a decline of their performance, which would then represent consequent economic loses.     

Freshwater ostracod assemblages and their relationship to environmental variables in waters from northeast Germany

An ecological calibration dataset for freshwater ostracods from 33 localities throughout West-Pomerania (Mecklenburg-Vorpommern, Germany) was evaluated using multivariate statistical methods. A total of 47 freshwater ostracod species were identified. Nine species were rediscovered after 100 years since the last published record and Candonopsis scourfieldi and Pseudocandona sucki was recorded for the first time in the study area. Special emphasis is put on the phenology of each species to gain information on the water characteristics at the time of their last moult. Canonical correspondence analysis (CCA) revealed that the ecological variables such as water temperature, Ca, Mg, and lake area were statistically most significant (p < 0.005; n = 72) in explaining variation in the distribution of ostracod assemblages. In addition, a transfer function was developed for paleolimnological approaches, based on a weighted-averaging (WA) model to calculate water temperature from the relative abundances of 22 selected ostracod species. This model was successfully applied to infer lake water temperature from subfossil ostracod assemblages collected from lacustrine deposits in northeast Germany (Lake Krakower See). Electronic supplementary material Electronic supplementary material is available for this article at and accessible for authorised users.     

Lithium as a normal metabolite: some implications for cyclotron resonance of ions in magnetic fields

Cyclotron resonance of ions has been proposed as a mechanism by which weak, extremely-low-frequency (ELF) electromagnetic fields can act on biological systems. Critics of a mechanism predicated on resonance of lithium have argued that this element is virtually absent from the internal milieu of mammals and otherwise plays no role in the normal physiological functioning of the organism. Sophisticated techniques of trace-element analysis have recently revealed that lithium is a normal constituent of tissues of assayed mammals, including those of rats and human beings. There is evidence, too, that lithium is an important, biologically-active element. Cyclotron resonance may or may not be a mechanism by which ELF- and static-magnetic fields at low strengths combine to affect the organism, but rejection of this mechanism on the grounds that lithium is absent or is physiologically inadequate is unwarranted. Lithium is normally present and is metabolically active in many tissues, especially those of the neuroendocrine system.     

Occurrence and densities of bacteriophages proposed as indicators and bacterial indicators in river waters from Europe and South America

AIMS: To evaluate the feasibility of bacteriophages as a complementary tool for water quality assessment in surface waters from different parts of the globe. METHODS AND RESULTS: Faecal coliform bacteria, enterococci, spores of sulphite-reducing clostridia, somatic coliphages, F-specific RNA bacteriophages and bacteriophages infecting Bacteroides fragilis were determined by standardized methods in raw sewage and in 392 samples of river water from 22 sampling sites in 10 rivers in Argentina, Colombia, France and Spain, which represent very different climatic and socio-economic conditions. The results showed that the indicators studied maintained the same relative densities in the raw sewage from the different areas. Classifying the river water samples according to the content of faecal coliform bacteria, it can be observed that the relative densities of the different bacterial indicators and bacteriophages changed according to the concentration of faecal coliform bacteria. There was a relative increase in the densities of all groups of bacteriophages and sulphite-reducing clostridia with respect to faecal coliforms and enterococci in the samples with low counts of faecal coliform bacteria. CONCLUSIONS: The numbers of bacterial indicators and bacteriophages were similar in the different geographical areas studied. Once released in rivers, the persistence of the different micro-organisms differed significantly. Bacteriophages and spores of sulphite-reducing clostridia persisted longer than faecal coliforms and enterococci. SIGNIFICANCE AND IMPACT OF THE STUDY: Bacteriophages in river water samples provide additional information to that provided by bacteria about the fate of faecal micro-organisms in river water. The easy, fast and cheap methods for phage determination are feasible both in industrialized and developing countries.     

Zinc,copper, and magnesium concentrations in hair of children from Southeastern Turkey

Zinc, copper, and magnesium concentrations in hair were measured in groups of children varying in one condition—protein-energy malnutrition, ricketts, thalassemia, malignancy, cardiac failure, or after prolonged infection and in healthy controls. As compared with controls, copper and magnesium concentrations were low in all groups, whereas higher values were obtained for hair zinc. These results showed that a generalized copper and magnesium deficiency were observed in the southeastern part of Turkey. However, zinc deficiency couldn’t be detected as far as the hair zinc values were concerned, although all of the subjects fell within the 50 percentile limits for their age-appropriate weights and heights.     

Magnesium and methionine deprivation affect the response of rats to boron deprivation

A series of nine experiments were done to obtain further evidence that boron might be involved in major mineral metabolism (Ca, P, and Mg), thus indicating that boron is an essential nutrient for animals. Eight factorially arranged experiments of 6–10 wk durations were done with weanling Sprague-Dawley male rats. One factorially arranged experiment was done with weanling spontaneously hypertensive rats. The variables in each experiment were dietary boron supplements of 0 and 3 μg/g, and dietary magnesium supplements of either 200 (Experiments 1–3) or 100 (Experiments 4–9) and 400 μg/g. In Experiments 7 and 9, a third variable was dietary manganese supplements of 25 and 50 μg/g. Methionine status was varied throughout the series of experiments by supplementing the casein-based diet with methionine and arginine. Findings were obtained indicating that the severity of magnesium deprivation and the methionine status of the rat strongly influence the extent and nature of the interaction between magnesium and boron, and the response to boron deprivation. When magnesium deprivation was severe enough to cause typical signs of deficiency, a significant interaction between boron and magnesium was found. Generally, the interaction was characterized by the deprivation of one of the elements making the deficiency signs of the other more marked. The interaction was most evident when the diet was not supplemented with methionine and especially when the diet contained luxuriant arginine. Signs of boron deprivation were also more marked and consistent when the diet contained marginal methionine and luxuriant arginine. Among the signs of boron deprivation exhibited by rats fed marginal methionine were depressed growth and bone magnesium concentration, and elevated spleen wt/body wt and kidney wt/body wt ratios. Because the boron supplement of 3 μg/g did not make the dietary intake of this element unusual, it seems likely that the response of the rats to dietary boron in the present study were manifestations of physiological, not pharmacological, actions, and support the hypothesis that boron is an essential nutrient for the rat. Mentions of a trademark or proprietary product does not consitute a guarantee or warranty of the product by the US Department of Agriculture and does not imply its approval to the exclusion of other products that may also be suitable.     

Mineral concentrations in whole mice and rats used as food

Calcium (Ca), magnesium (Mg), copper (Cu), iron (Fe), manganese (MD), and zinc (Zn) concentrations were measured in whole mice (five sizes) and rats (six sizes). Ca concentrations increased with age in both mice (1.2–2.3%) and rats (1.9–3.3%). Mg levels ranged from 0.09 to 0.13% (mice) and from 0.11 to 0.18% (rats), with the medium-size class of both species having the highest values. Cu (7.9–19.2 and 10.8–60.6 mg/kg) and Zn (58.0–82.5 and 73.2–113.6 mg/kg) generally decreased with age in both species, while Mn levels tended to increase with age (0.2–13.1 mg/kg, mice; 6.2–28.3 mg/kg, rats). Fe values were highest in neonates and adult size classes, ranging from 113.4 to 181.3 mg/kg (mice) and 111.3 to 332.6 mg/kg (rats). Rats usually contained higher concentrations of individual minerals than equivalent age categories of mice, even though both were fed identical diets. All rodents analyzed generally met known dietary requirements of mammalian carnivores, but differences between mice and rats were apparent. Specific mineral nutrient requirements for carnivorous birds and reptiles have not been determined. © 1996 Wiley-Liss, Inc.