Changes in the concentration of ions during senescence of the human erythrocyte.

Flash frozen samples of normal human blood were cryosectioned and cryodried for electron probe x-ray microanalysis of the concentration of ions and elements in individual erythrocytes (RBCs). The data (expressed in mM/kg dry weight) demonstrated a systematic pattern of variation between the concentration of ions and elements in the RBCs. Specifically as K+ and Cl- decreased in concentration, Ca2+ and sulfur increased in concentration. Phosphorous, Na+ and Mg2+ did not demonstrate a significant pattern of change. These findings are related to the dehydration and to the volume decrease that accompanies senescence of the RBC.

The locations and amounts of endogenous ions and elements in the cap and elongating zone of horizontally oriented roots of Zea mays L.: an electron-probe EDS study.

We used quantitative electron-probe energy-dispersive x-ray microanalysis to localize endogenous Na, Cl, K, P, S, Mg and Ca in cryofixed and freeze-dried cryosections of the cap (i.e. the putative site of graviperception) and elongating zone (i.e. site of gravicurvature) of horizontally oriented roots of Zea mays. Ca, Na, Cl, K and Mg accumulate along the lower side of caps of horizontally oriented roots. The most dramatic asymmetries of these ions occur in the apoplast, especially the mucilage. We could not detect any significant differences in the concentrations of these ions in the central cytoplasm of columella cells along the upper and lower sides of caps of horizontally-oriented roots. However, the increased amounts of Na, Cl, K and Mg in the longitudinal walls of columella cells along the lower side of the cap suggest that these ions may move down through the columella tissue of horizontally-oriented roots. Ca also accumulates (largely in the mucilage) along the lower side of the elongating zone of horizontally-oriented roots, while Na, P, Cl and K tend to accumulate along the upper side of the elongating zone. Of these ions, only K increases in concentration in the cytoplasm and longitudinal walls of cortical cells in the upper vs lower sides of the elongating zone. These results indicate that (1) gravity-induced asymmetries of ions differ significantly in the cap and elongating zone of graviresponding roots, (2) Ca accumulates along the lower side of the cap and elongating zone of graviresponding roots, (3) increased growth of the upper side of the elongating zone of horizontally-oriented roots correlates positively with increased amounts of K in the cytoplasm and longitudinal walls of cortical cells, and (4) the apoplast (especially the mucilage) may be an important component of the pathway via which ions move in graviresponding rots of Zea mays. These results are discussed relative to mechanisms for graviperception and gravicurvature of roots.

The effects of increased levels of niacin supplementation on growth rate and carcass composition of broiler chickens.

Four experiments were conducted to examine the response of broiler chickens to different levels of niacin. Practical-type diets, calculated to contain from 20.7 to 23.7 mg niacin per kg from intact ingredients, were fortified with a complete vitamin mixture which provided 33 mg supplemental niacin per kg of diet, in excess of the National Research Council (1977) suggested requirement of 27 mg per kg through 6 weeks of age. A niacinamide supplement was used to provide additional levels of 0, 33, or 66 mg per kg. Diets differed in content of added fat and energy levels in two of the experiments and in the presence or absence of animal protein sources in two others. The addition of niacinamide at 33 and 66 mg per kg to a diet already supplemented with 33 mg per kg from a complete vitamin premix, calculated to exceed the present NRC suggested requirement, resulted in improved body weight gains with sex differences noted in some experiments. Feed utilization was improved in some studies. There was no effect on the amount of abdominal fat or carcass dressing percentage. The results of these studies indicate that the modern rapidly growing broiler chick may require niacin levels greater than those generally recommended by the National Research Council (1977), which are based largely on studies where performance was considerably lower than obtained with the modern strains of broilers.

Intracellular elemental content of cardiac and skeletal muscle of normal and dystrophic hamsters.

To test the hypothesis that the genetic lesion causing muscular dystrophy might be reflected in an abnormal intracellular elemental content, the elemental content of individual cardiac and skeletal muscle fibers in 50-day-old male control and cardiomyopathic BIO 53.58 hamsters was determined. The technique of electron probe x-ray microanalysis of freeze-dried tissue was employed. No electrolyte content differences were found between control and diseased animals for nuclei, myofibrillar cytoplasm, or mitochondrially-enriched cytoplasm of cardiac myocytes. Sulfur was elevated in dystrophic cardiac myocytes and was the only element significantly different in heart tissue of control and cardiomyopathic animals. Sulfur was also elevated in dystrophic soleus muscle fibers. The pattern of electrolyte content of these cells reflected a mixture of normal cells and damaged cells with altered electrolyte content. In this hamster model, alteration of electrolyte content of myocytes appears to be a result of the disease process and not an inherent characteristic of muscular dystrophy. The elevated sulfur in dystrophic hamster myocytes reflects a biochemical lesion which deserves further study.

Effect of experimental hyperthyroidism on the elemental content of rat hepatocytes.

X-ray microanalysis has been used to determine elemental content in the cytoplasm of hepatocytes of hyperthyroid rats in comparison with euthyroid controls. No significant differences were found for any examined element (sodium, phosphorus, sulfur, chlorine, potassium, magnesium and calcium). In contrast to earlier reports from another laboratory, these data indicate that thyroid hormones do not substantially affect elemental content in rat hepatocytes.

Cell cycle-fluctuations in concentration of various elements in cytoplasm and in nucleus/chromatin of Physarum polycephalum.

The concentrations of Na, Mg, P, Cl, S, K, and Ca (m mol/kg dry wt) were measured during the cell cycle of P. polycephalum using electron-probe X-ray microanalysis. Significant cell cycle-associated fluctuations in the concentrations of all of these elements occurs in both the cytoplasm and the nucleus. In most cases the levels of each element were elevated during mitosis but greatly reduced during the S phase. Phosphorus and sulphur were concentrated in the nucleus/chromatin at metaphase. Ultrastructural analysis of these cells reveals a phase dependent variation in the density of the cytoplasmic ground substance which is most pronounced at mitosis. The changes seen in the cytoplasm occur not only in conjunction with the increased concentration of elements in the nucleus but also with the cessation of protoplasmic migration.

Observations on electron probe x-ray microanalysis compared to other methods for measuring intracellular elemental concentration.

Electron probe X-ray microanalysis provides the capability of accurately measuring the concentration of a number of elements at the subcellular level in tissues which are appropriately prepared using cryofixative procedures. This preview compares quantitative data obtained by the authors, using X-ray microanalysis, with quantitative data obtained in other laboratories using routine chemical procedures such as flame photometry, atomic absorption spectrophotometry, titrimetry, and ion-selective electrodes. Results are compared for cells in whole tissue, for cells in suspension (erythrocytes), and for subcellular analysis. Subcellular elemental data obtained after cell fractionation and isolation and after cryomicrodissection are considered. Agreements and differences between the results obtained by the different methods of analysis as compared to microprobe are discussed and the sources of the differences are explored. The biological significance of microprobe concentration data itself is limited without additional information regarding the state of the elements, such as oxidation state, ionic activity, degree of binding, etc. In this regard, the supplementation of subcellular elemental concentration with ionic activity and flux data for the large amphibian oocyte is presented as an example of how measurement of multiple parameters can be used to explain the maintenance of subcellular concentration gradients.

Intracellular concentration of potassium and other elements in vaginal epithelial cells stimulated by estradiol administration.

Electron probe x-ray microanalysis was used to measure cytoplasmic elemental content (in mmoles/kg dry weight) of the basal layer of cells of the vaginal epithelium of ovariectomized rats. Measurements were made both before estradiol injection and at 2 hr, 17 hr, and 24 hr after estradiol administration. Mitotic figures first appeared in the basal cell layer at 24 hr. During the course of the study significant time-dependent differences were seen in the content of all elements mesured. A pattern of change in cytoplasmic content was seen for Na, P, S, and Cl; all of which decrease significantly by 17 hr and then return to approximately the nonstimulated concentration by 24 hr. On the other hand K, and to a lesser extent Mg, show an early and continued increase in cytoplasmic content after estadiol injection. Thus, the marked increase in the intracytoplasmic content of K in the estradiol treated cells suggests that K, or the ratio of Na to K, may be directly or indirectly involved in growth stimulation.

Intracellular concentration of elements in normal and dystrophic skeletal muscles of the chicken.

In this study, the intracellular concentrations of six elements (mmole/kg dry weight) were directly measured in the muscle fibers of pectoralis major muscles of eight week old, genetically dystrophic and normal chickens by the X-ray microanalysis technique. The extent of muscle degeneration was evaluated by morphometric measurements of muscle fiber diameter and other histological changes. A significant increase in the concentration of intracellular sodium and chlorine was evident in dystrophic muscles. The concentration of intracellular sodium was 127.0 +/- 35.0 in the muscle fibers of dystrophic chicks compared to 65.7 +/- 16.5 in normal controls. The concentration of chlorine was 90.5 +/- 27.5 and 54.1 +/- 5.5 in the muscle fibers of dystrophic and normal chicks respectively. The intracellular concentrations of potassium, magnesium, phosphorous, and sulfur remained unchanged in the dystrophic condition. Morphometric studies revealed that the dystrophic pectoralis muscles contain fewer but thicker fibers per unit area compared to normal pectoralis muscles. The importance of these findings are discussed in relation to the results of earlier investigations.

An X-ray microanalysis survey of the concentration of elements in the cytoplasm of different mammalian cell types.

Electron probe energy dispersive X-ray microanalysis was performed on freeze-dried tissue sections. The dry weight concentration of elements (mmole/kg dry weight) was measured in the cytoplasm of several cell types from adult mice and rats. This comparative investigation showed: (1) That the energy dispersive X-ray spectrum of element concentration from the cytoplasm of a specific cell type allows one to distinguish this specific cell type from other cell types with considerable accuracy. (2) That there is a relationship between the concentration of the various elements and the ultrastructural features of the cytoplasmic regions being analyzed. For example, areas rich in ribosomes are also rich in P, K and Mg. (3) These data support the idea that K is directly involved in the control of protein synthesis. The catalog of element concentrations in the cytoplasm of 13 cell types from both mice and rats should be of value to others who seek to answer various questions about these cell types.

Electron probe microanalysis of elemental composition of mouse cardiac myocytes during post-natal maturation.

Elemental concentrations in the cytoplasm and nucleus of t tests post-natal mouse myocytes were measured at 2, 4, 8, 16, 32 days and in adults using electron probe X-ray microanalysis. Using an analysis of variance test, significant age dependent changes were found in intracellular potassium, sulfur, phosphorus, and chlorine concentrations (mg/kg dry weight), while sodium and magnesium concentrations did not show significant changes. The application of t tests following linear regression analyses (age versus concentration for each element) did, however, give a significant slope for cytoplasmic sodium, potassium, sulfur, and phosphorus values. The findings correspond closely with an emission spectroscopy-titrimetric study of whole heart ventricle of the same developmental period (Hazelwood and Nichols, '70).