Effect of ruthenium complexes on the activities of succinate dehydrogenase and cytochrome oxidase

In this article, we report the effects of acute administration of ruthenium complexes, trans-[RuCl(2)(nic)(4)] (nic=3-pyridinecarboxylic acid) 180.7 micromol/kg (complex I), trans-[RuCl(2)(i-nic)(4)] (i-nic=4-pyridinecarboxylic acid) 13.6 micromol/kg (complex II), trans-[RuCl(2)(dinic)(4)] (dinic=3,5-pyridinedicarboxylic acid) 180.7 micromol/kg (complex III) and trans-[RuCl(2)(i-dinic)(4)]Cl (i-dinic=3,4-pyridinedicarboxylic acid) 180.7 micromol/kg (complex IV) on succinate dehydrogenase (SDH) and cytochrome oxidase (COX) activities in brain (hippocampus, striatum and cerebral cortex), heart, skeletal muscle, liver and kidney of rats. Our results showed that complex I inhibited SDH activity in hippocampus, cerebral cortex, heart and liver; and inhibited COX in heart and kidney. Complex II inhibited SDH in heart and hippocampus; COX was inhibited in hippocampus, heart, liver and kidney. SDH activity was inhibited by complex III in heart, muscle, liver and kidney. However, COX activity was increased in hippocampus, striatum, cerebral cortex and kidney. Complex IV inhibited SDH activity in muscle and liver; COX activity was inhibited in kidney and increased in hippocampus, striatum and cerebral cortex. In a general manner, the complexes tested in this work decrease the activities of SDH and COX in heart, skeletal muscle, liver and kidney. In brain, complexes I and II were shown to be inhibitors and complexes III and IV activators of these enzymes. In vitro studies showed that the ruthenium complexes III and IV did not alter COX activity in kidney, but activated the enzyme in hippocampus, striatum and cerebral cortex, suggesting that these complexes present a direct action on COX in brain.     

Dynamic proteomics in individual human cells uncovers widespread cell-cycle dependence of nuclear proteins

We examined cell cycle-dependent changes in the proteome of human cells by systematically measuring protein dynamics in individual living cells. We used time-lapse microscopy to measure the dynamics of a random subset of 20 nuclear proteins, each tagged with yellow fluorescent protein (YFP) at its endogenous chromosomal location. We synchronized the cells in silico by aligning protein dynamics in each cell between consecutive divisions. We observed widespread (40%) cell-cycle dependence of nuclear protein levels and detected previously unknown cell cycle-dependent localization changes. This approach to dynamic proteomics can aid in discovery and accurate quantification of the extensive regulation of protein concentration and localization in individual living cells.     

Phosphate Starvation Inducible Metabolism in Lycopersicon esculentum: III. Changes in Protein Secretion under Nutrient Stress

Phosphate starvation increased the secretion of at least six proteins by suspension cultured tomato (Lycopersicon esculentum L. and L. pennellii) cells. Cells exhibited a biphasic response to phosphate (Pi) starvation. The early phase involved enhanced secretion of three proteins in response to transfer to a Pi-depleted media, while biomass accumulation continued at the same rate as in the Pi-sufficient cells. Severe starvation, defined as inhibition of biomass accumulation, induced enhanced secretion of three additional proteins. After sodium dodecyl sulfate-polyacrylamide gel electrophoresis, media proteins were immunoblotted with antibodies reacting specifically to oligosaccharides processed by the Golgi apparatus. Binding patterns showed that the enhancement in secretion during both phases of starvation was Golgi-mediated. Cells undergoing severe starvation had a respiration rate approximately twice that of unstressed cells and secreted 4.4 times more protein into the media per unit biomass. These data suggest overlapping Pi starvation-specific and global stress responses in plant cells. Under these conditions, Golgi-mediated protein secretion is enhanced. We present evidence for phosphate starvation inducible enhancement of Pi uptake. Secreted proteins specific for N and Fe starvation are also identified.     

Distribution of surface charge and concanavalin a-binding sites on normal and malignant transformed cells

Measurement of the rate of agglutination with the positively charged poly- -lysine of normal lymphocytes, Moloney-virus-transformed lymphoma cells, normal fibroblasts and SV40 transformed fibroblasts, has shown that the normal cells were agglutinated at a higher rate than the transformed cells. The labeling density of cationized ferritin in electron micrographs of sectioned cells, also indicated a higher charge density for the normal lymphocytes and fibroblasts. The normal cells showed a more regular clustered distribution of cationized ferritin than the transformed cells, and pre-fixation of cells with glutaraldehyde before labeling with cationized ferritin resulted in a random distribution in both types of cells. The transformed cells had a higher agglutinability than the normal cells by Concanavalin A (ConA) and this difference was also found after treatment of the cells with neuraminidase. Labeling with ConA-ferritin showed the same distribution on the sectioned normal and transformed cells. The results indicate that there was a difference in the redistribution of surface charge by cationized ferritin in normal and transformed cells and that there was no detectable difference in redistribution of ConA-binding sites with ConA-ferritin.     

The effect of sex on the uptake of very low density lipoprotein triglyceride fatty acid from the plasma of the rat in vivo.

Radioactive very low density lipoprotein (VLDL) was prepared by perfusion in vitro of livers isolated from normal fed male and female rats with [1-¹⁴C] oleate or [9, 10-³H] oleate, respectively. These VLDL, whose properties differed due to sex, were mixed. Aliquots of the mixture were injected intravenously into fasted male and female rats and the decay of the radioactivity (¹⁴C and ³H) was measured. Disappearance of radioactivity from plasma triglyceride was more rapid in female animals. Plasma half-life of ¹⁴C and ³H was 42.5±3.7 and 49.7±4.4 minutes, respectively, when the VLDL mixture was injected into male rats. The corresponding values in female rats were 28.3±1.1 and 30.7±1.7, respectively. These data suggest strongly that the rate of utilization of VLDL triglyceride fatty acid is more rapid in the female than in the male, and that the properties of the VLDL particles are of less importance than innate sex differences in the recipient for the rate of clearance of triglyceride fatty acids.     

The menstrual cycle and susceptibility to virtual simulation sickness

Virtual simulation sickness (VSS) is a form of visually induced motion sickness that can result from immersion in a virtual environment (VE). As in their susceptibility to the sickness induced by real motion, women have been reported to be more susceptible than men to VSS, yet the reason for this difference is not known. The aim of the current study was to investigate the influence of the menstrual cycle on susceptibility to VSS in 16 naturally cycling women and to compare the responses of this group with control groups consisting of 1) 16 premenopausal women taking a combined monophasic oral contraceptive and 2) 16 men. All female participants were immersed in a nauseogenic VE on days 5, 12, 19, and 26 of their menstrual/pill cycle. These days were chosen because they fall in line with peaks and troughs of ovarian hormone levels. Menstrual cycle phase was confirmed by salivary estradiol and progesterone levels. A 4-week "pseudo-cycle" was assigned to the male participants. Hormone analysis revealed that 9 participants in the experimental group had been tested at the desired phases of their cycle. These participants exhibited a significant increase in susceptibility to VSS on day 12 of their cycle. The hormone analysis also showed that the cycles of the 7 remaining members of the experimental group had not precisely followed the expected pattern, and so these people had been tested on days that did not coincide with peaks and troughs of ovarian hormone levels. No consistent variation in susceptibility was observed over the cycle in these volunteers. In addition, no change in susceptibility was observed over the pill cycle of the oral contraceptive group nor over the pseudo-cycle applied to the male control group. The authors conclude that susceptibility to VSS varies over the menstrual cycle as a consequence of hormonal variation.     

REDUCTION IN SURFACE CHARGE AS AN EXPLANATION OF THE RECOGNITION BY MACROPHAGES OF NUCLEI EXPELLED FROM NORMOBLASTS

The density and distribution of electric charge on the surface of rabbit bone marrow cells was visualized by electron microscopy after the cell surfaces had been stained with charged colloidal iron particles. Expulsed erythroid nuclei are less negatively charged than any other cell in the bone marrow. They carry from about one-half to one-third of the charge density on the remaining future reticulocyte. The reduction in the surface charge density is already apparent when the nucleus is partially expulsed. Practically no positive charge was found on its surface or on the surface of any other bone marrow cell. The possibility that the reduced negative charge on the surface of expelled erythroid nuclei is one of the means by which the macrophage distinguishes it from other bone marrow cells is discussed.     

AN ELECTRON MICROSCOPIC STUDY OF NUCLEAR ELIMINATION FROM THE LATE ERYTHROBLAST

The process of expulsion of the nucleus during the transformation of the late erythroblast to reticulocyte is described. Erythroid clones taken from the spleen of lethally irradiated mice transplanted with syngeneic bone marrow were used. 10–12-day old isolated clones were fixed in glutaraldehyde, then in osmium tetroxide. Ultra-thin sections were stained with uranyl acetate and/or lead citrate before examination. Late (orthochromatic) erythroblasts develop pseudopod-like cytoplasmic protrusions into one of which the nucleus gradually penetrates, being deformed by the extrusion through the relatively narrow passage. During the whole process, mitochondria and vesicular and membranous elements are concentrated in the cytoplasm. Once outside the cell, the nucleus reassumes its rounded form. It is surrounded by a narrow rim of cytoplasm and structurally altered plasma membrane and is connected to the rest of the cell by a bridge. Elongated vacuoles appear within this bridge, with a resulting release of the enveloped nucleus which is soon phagocytized by macrophages; this leaves behind the newly formed reticulocyte. During this process, the cytoplasmic protrusions, the agglomeration of mitochondria, and the mode of separation of the nucleus from the rest of the cell are similar to those occurring in mitotic division.     

Phosphate starvation stress as an experimental system for molecular analysis

Journal article #6006 of the Arizona Agricultural Experiment Station