Role of membrane transport of water and glycerol in the freeze tolerance of the rice stem borer, Chilo suppressalis Walker (Lepidoptera: Pyralidae)

Overwintering larvae of the rice stem borer, Chilo suppressalis accumulate glycerol and are freezing tolerant to about -25 degrees C. However, non-diapausing larvae cannot accumulate glycerol and are killed by freezing. We compared the extent of tissue damage, the effects of glycerol concentration, and the transport of glycerol and water in fat body tissues from these larvae at selected freezing temperatures. Tissues from overwintering larvae, but not non-diapausing larvae, survive when frozen at -20 degrees C with 0.25 M glycerol, but the protection afforded by glycerol is offset by the water-channel inhibitor mercuric chloride. Glycerol in higher concentration (0.75 M) affords some protection even to the fat body of non-diapausing larvae. Radiotracer assays of overwintering larvae show that water leaves the tissues during freezing while glycerol enters, and that mercuric chloride disrupts this process. Transport is also disrupted after lethal freezing at -35 degrees C. Therefore, membrane transport of water and glycerol is involved in the avoidance of freezing injury to fat body cells of the rice stem borer, apparently by mediating the replacement of water with glycerol in freezing-tolerant tissues.     

Transient loss of plasmid-mediated mercuric ion resistance after stress in Pseudomonas aeruginosa

After freezing and thawing, Pseudomonas aeruginosa harboring a drug resistance plasmid (Hg2+r, Strr), became acutely sensitive to mercuric ions but not to streptomycin in the plating medium, whereas its sensitivity to both agents became more pronounced indicating a synergistic effect. This freeze-thaw-induced sensitivity was transient and capable of being repaired to a simple salts medium. Transient outer and cytoplasmic membrane damage was also observed in frozen and thawed preparations. From kinetics studies, repair of cytoplasmic membrane damage superseded repair of outer membrane damage and damage measured by mercuric ions and mercuric ions plus streptomycin. Osmotically shocked cells were also sensitive to mercuric ions, mercuric ions plus streptomycin, and sodium lauryl sulfate, but not to sodium chloride or streptomycin alone. This sensitivity was again transient and capable of repair in the same simple salts medium. Active transport of a non-metabolizable amino acid, alpha-amino isobutyric acid, was sensitive to mercuric ions and became more so after freezing and thawing. A freeze-thaw-resistant mercuric ion-dependent reduced nicotinamide adenine dinucleotide phosphate oxidoreductase was localized in the cytoplasm of this organism. This enzyme and an intact outer membrane appear to be required for mercuric ion resistance in this strain.     

Transient loss of plasmid-mediated mercuric ion resistance after stress in Pseudomonas aeruginosa.

After freezing and thawing, Pseudomonas aeruginosa harboring a drug resistance plasmid (Hg2+r, Strr), became acutely sensitive to mercuric ions but not to streptomycin in the plating medium, whereas its sensitivity to both agents became more pronounced indicating a synergistic effect. This freeze-thaw-induced sensitivity was transient and capable of being repaired to a simple salts medium. Transient outer and cytoplasmic membrane damage was also observed in frozen and thawed preparations. From kinetics studies, repair of cytoplasmic membrane damage superseded repair of outer membrane damage and damage measured by mercuric ions and mercuric ions plus streptomycin. Osmotically shocked cells were also sensitive to mercuric ions, mercuric ions plus streptomycin, and sodium lauryl sulfate, but not to sodium chloride or streptomycin alone. This sensitivity was again transient and capable of repair in the same simple salts medium. Active transport of a non-metabolizable amino acid, alpha-amino isobutyric acid, was sensitive to mercuric ions and became more so after freezing and thawing. A freeze-thaw-resistant mercuric ion-dependent reduced nicotinamide adenine dinucleotide phosphate oxidoreductase was localized in the cytoplasm of this organism. This enzyme and an intact outer membrane appear to be required for mercuric ion resistance in this strain.     

The cellular origin and proliferative status of regenerating renal parenchyma after mercuric chloride damage and erythropoietin treatment

OBJECTIVES: In this study, we have sought to establish the cellular origin and proliferative status of the renal parenchyma as it regenerates after damage induced by mercuric chloride, with or without erythropoietin treatments, that might alter the response. MATERIALS AND METHODS: Female mice were irradiated and male whole bone marrow was transplanted into them. Six weeks later recipient mice were assigned to one of four groups: control, mercuric chloride treated, erythropoietin treated and treated with mercuric chloride plus erythropoietin. RESULTS: Tubular injury scores were high 3 days after mercuric chloride and had recovered partially after 14 days, in line with serum urea nitrogen levels. Confocal microscopy confirmed the tubular location of bone marrow-derived cells. A 'four-in-one' analytical technique (identifying cell origin, tubular phenotype, tubular basement membranes and S-phase status) revealed that tubular necrosis increased bone marrow derivation of renal tubular epithelium from a baseline of approximately 1.3% to approximately 4.0%. Erythropoietin increased the haematocrit, but no other effects were detected. CONCLUSION: As 1 in 12 proximal tubular cells in S-phase was derived from bone marrow, we conclude that in the kidney, the presence of bone marrow-derived cells makes a minor but important regenerative contribution after tubular necrosis.     

Mercury incorporation by mature and immature red blood cells

Intact and ghost erythrocytes and reticulocytes were incubated with 0.1 ppm 203-Hg as either mercuric chloride or methyl mercury chloride. Both mature and immature cells accumulated alkyl mercury more avidly than inorganic mercury. Methyl mercury chloride, but not mercuric chloride, readily penetrated the membrane and became incorporated into the intracellular compartment of intact cells. Although uptake of alkyl mercury was approximately the same for intact erythrocytes and reticulocytes, developing cells accumulated inorganic mercury more avidly than did mature cells. Increased uptake of inorganic mercury represented predominantly an increase in stromal binding, illustrating differences in the surface membrane or reticulocytes and erythrocytes.     

Development of a biological mercury removal-recovery system

A mercury removal-recovery system was developed for collection of elemental mercury volatilized by biological mercuric ion reduction. Using the mercury removal-recovery system, removal of mercuric chloride from mercury-containing buffer without nutrients by resting cells of mercury-resistant bacterium, Pseudomonas putida PpY101/pSR134 was tested. Optimum temperature, pH, thiol compounds and cell concentration on removal of mercuric chloride were determined, and 92 to 98% of 40 mg Hg l^–1 was recovered in 24 h. The efficiency of mercuric chloride removal from river water and seawater was as high as that observed when using a buffered solution.     

Hematotoxicity and Genotoxicity of Mercuric Chloride Following Subchronic Exposure Through Drinking Water in Male Rats

Erythrocytes are a convenient model to understand the subsequent oxidative deterioration of biological macromolecules in metal toxicities. The present study examined the variation of hematoxic and genotoxic parameters following subchronic exposure of mercuric chloride via drinking water and their possible association with oxidative stress. Male rats were exposed to 50 ppm (HG1) and 100 ppm (HG2) of mercuric chloride daily for 90 days. A significant dose-dependent decrease was observed in red blood cell count, hemoglobin, hematocrit, and mean cell hemoglobin concentration in treated groups (HG1 and HG2) compared with controls. A significant dose-dependent increase was observed in lipid peroxidation; therefore, a significant variation was found in the antioxidant enzyme activities, such as superoxide dismutase, catalase, and glutathione peroxidase. Interestingly, mercuric chloride treatment showed a significant dose-dependent increase in frequency of total chromosomal aberration and in percentage of aberrant bone marrow metaphase of treated groups (p < 0.01). The oxidative stress induced by mercury treatment may be the major cause for chromosomal aberration as free radicals lead to DNA damage. These data will be useful in screening the antioxidant activities of natural products, which may be specific to the bone marrow tissue.     

Mercuric chloride-induced nephrotoxicity in the rat following unilateral nephrectomy and compensatory renal growth

The nephropathy induced by mercuric chloride was assessed in unilaterally nephrectomized (NPX) and sham-operated (SO) rats using histological and urinalysis techniques. This assessment was carried out in order to test whether or not rats are more susceptible to the nephrotoxic effects of mercuric chloride after unilateral nephrectomy and a period allowing for compensatory renal growth. Twelve days after surgery both NPX and SO rats were given a single 1.5, 2.0 or 2.5 mumol/kg dose of mercuric chloride (i.v.). Twenty-four hours after the 1.5 or 2.0 mumol/kg dose of mercuric chloride was administered, cellular and tubular necrosis in the pars recta segments of proximal tubules in the outer medulla was more severe in NPX rats than in SO rats. Moreover, the urinary excretion of a number of cellular enzymes (e.g. lactate dehydrogenase) and plasma solutes (e.g. albumin) was greater in NPX rats than in SO rats. At the 2.5 mumol/kg dose of mercuric chloride, renal tubular damage was quite extensive in both groups of rats; to such an extent that possible differences in renal tubular damage between the NPX and SO rats could not be determined histologically. However, the urinary excretion of alanine aminopeptidase was greater in the NPX rats than in the SO rats. Therefore, based on the aforementioned findings, rats that have undergone and adapted to a reduction in renal mass (i.e. unilateral nephrectomy) appear to be more vulnerable to the nephrotoxic effects of mercuric chloride than rats with two normal kidneys.     

Experimental study on the estrogen-like effect of mercuric chloride

Although mercuric chloride has toxicity on reproductive system, it is uncertain if such toxicity is induced by estrogen-like effect. To study whether mercuric chloride has the estrogen-like effect and its relevant mechanism, proliferation assay of MCF-7 human breast cancer cells, uterotrophic assay, peroxidase activity assay and estrogen receptor competitive binding assay were conducted to screen the estrogen-like effect of mercuric chloride. The MCF-7 cells proliferated in the stimulation of mercuric chloride and got to the peak at 10⁻⁷ mol/l concentration. And this proliferation could be completely blocked by estrogenic antagonist ICI182.780. In addition, mercuric chloride could increase the weight of uterus of ovariectomized SD rats and the peroxidase activity of uterus complying with dose-effect relationship. However, mercuric chloride could not affect the binding of estradiol (E₂) to estrogen receptor (ER). So mercuric chloride exhibits the estrogen-like effect through binding and activating ER rather than bind to ER by competing with E₂.     

The Inflammatory Potential of Dietary Manganese in a Cohort of Elderly Men

In the current study, 48 male rats were classified into four groups (12 rats/group): 1—control group received 1 ml distilled water, 2—origanum oil group treated daily with oral dose of origanum oil (5 mg/kg) for 30 and 60 days, 3—mercuric chloride group treated daily with oral dose of mercuric chloride (4 mg/kg) for 30 and 60 days, and 4—origanum oil + mercuric chloride group treated with both origanum oil and mercuric chloride (5 and 4 mg/kg, respectively) for 30 and 60 days. All treatments were carried out by stomach tube. The results showed that administration of mercuric chloride induced significant increase in thiobarbituric acid reactive substance (TBARS) and decrease in glutathione (GSH), catalase (CAT), and super oxide dismutase (SOD) in testis and spleen tissues. The data also showed significant increase in tumor necrossis factor-α (TNF-α), 8-hydroxy deoxyguanosine (8-OHDG), acid phosphatase (ACP), urea, and creatinine. Furthermore, significant decreases in serum zinc (Zn), copper (Cu), magnesium (Mg), iron (Fe), and testosterone in mercuric chloride group were recorded. The histological examination of testis and spleen tissues showed some degenerative changes while significant improvement in the antioxidant levels, biochemical, trace elements, and histological changes were observed in mercuric chloride group treated with origanum oil. It could be concluded that origanum oil through its antioxidant potential may possess health promoting properties and could protect cells from oxidative damage induced by mercuric chloride.     

Cleavage of Disulfide Bonds of Wheat Glutenin by Mercuric Chloride

The dissociation of wheat glutenin into subunits was observed by treatment with a small amount of mercuric chloride under moderate conditions, suggesting that the cleavage of inter-polypeptide chain disulfide bonds in the glutenin might occur. The dissociation into the subunits was examined by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis. The electrophoretic patterns of the glutenin treated with mercuric chloride were essentially similar to those of the glutenin treated with 2-mercaptoethanol. Silver nitrate also had the same effects as mercuric chloride, and p-chloromercuribenzoate and N-ethylmaleimide showed no effect on the dissociation of the glutenin. Complete dissociation was achieved when the glutenin solution containing 0.5% SDS and 0.01 m phosphate buffer (pH 7.0) was incubated with 10^?3 m mercuric chloride (about four moles per mole of disulfide groups) at 30°C for 20 hr. Partial dissociation was also observed after 30 min incubation. Increasing temperature and SDS concentration promoted the rate of the dissociation of the glutenin by mercuric chloride.     

Cytochemical localization of mercury in Saccharomyces cerevisiae treated with mercuric chloride

We describe a cytochemical method for localizing mercury at the electron microscopic level in the yeast Saccharomyces cerevisiae. After addition of a lethal concentration of mercuric chloride to growing yeast cells, mercury was associated with the cell wall and cytoplasmic membrane. Little or no mercury was present in the cytoplasm. Electron probe X-ray microanalysis (EPMA) confirmed that the cytochemical reaction, visualized as mercury-silver complexes, was localized in dense bodies consisting of a core of mercury sulfide polymers surrounded by a shell of silver atoms.     

Uptake of mercury and mercury-amino acid complexes by rat renal cortex slices.

This study was undertaken in order to assess the effects of metabolism and complexations with amino acids on the renal uptake of mercury using rat renal cortex slices as the experimental system. Mercury levels attained in the slices after 60 min of incubation were 50% higher with mercuric cysteine than with mercuric chloride. This enhancement of uptake with mercuric cysteine was reduced in the presence of a tenfold molar excess of histidine or lysine, but not by serine. Excess cysteine markedly increased mercury uptake. Incubation at 25 degrees significantly reduced uptake of mercuric cysteine, but not mercuric chloride. Anaerobic conditions and incubation in the presence of DNP each reduced mercuric cysteine uptake to the control level of mercuric chloride without affecting uptake of mercuric chloride. The differential aspects of metabolism on the uptake of mercuric cysteine and mercuric chloride and the competitive effects obtained with amino acids known to compete with cysteine in renal reabsorption support the hypothesis that a portion of the renal uptake of mercury operates through amino acid transport mechanisms acting on mercury-amino acid complexes.     

氯化高汞对大型溞的慢性毒性

在换水静置条件下(25℃),氯化高汞(以Hg++计)对大型溞的48小时LC50值及其可信限为13.5(±2.1)微克/升。试验个体饲以斜生栅藻单个培养,在汞含量为1—21微克/升浓度下,产仔总数经方差分析表明组间差异显著(FF0.05)。各浓度组(X)与产仔总数(Y)的关系为:Y=-51.823X+4320.960(r=-0.904,p0.01)。净增殖率(R0)随浓度升高而逐渐下降。存活和生长用方差分析及D值检验表明对照组与各浓度组之间(差异数分别小于各自的D值20.89和0.1749),没有显著差异。各浓度组对内禀增长能力(rm)和世代平均周期(T)影响不大。根据大型溞的生物学基本参数,其体长的生长模型为: lt=4.57-3.5177e-0.00838t.       

Metachromasia of basic dyes induced by mercuric chloride. I

Summary Interactions of the cationic dye methylene blue with mercuric chloride have been studied conductometrically, analytically and spectrophotometrically. Methylene blue produces red colored precipitate with mercuric chloride; in presence of large excess of mercuric chloride a strong metachromasia is induced in the dye. Metachromasia induced by mercuric chloride is more hypsochromic as well as hypochromic than that induced by chromotopes like heparin. The complexes formed between methylene blue and mercuric chloride have variable compositions, the complex responsible for the red metachromatic color of the dye has the composition 2 dye: 1 HgCl₂. A model has been proposed for the metachromatic complex consisting hexa-coordinated mercury, dye is coordinated to the mercury by donating the lone pair electrons of terminal nitrogen. The non-metachromatic dye capri blue also interacts with mercuric chloride but without any change in the visible spectrum. Potassium iodide also gives metachromatic reddish blue colored precipitate with methylene blue.University Research Scholar.     

Uptake of mercury by Chlorella and its effect on potassium regulation

Summary Addition of mercuric chloride at concentrations which resulted in an overall binding level of about 8 mmoles Hg/l packed cells and above caused a breakdown in the permeability of the cell membrane as indicated by a net efflux of internal K⁺. Below this level in region of 2 mmoles Hg/l packed cells the rate of K⁺ transfer across the cell surface was stimulated without affecting the internal K⁺ level. Maintainence of the stimulation was dependent both on time and dose. Enhancement of the rate of K⁺ turnover was associated with a fast component of the inorganic mercury uptake which could be removed by washing with cysteine. The mercury stimulated K⁺/K⁺ exchange was inhibited by low temperature, by the uncoupler CCCP and the energy transfer inhibitor DCCD. Overall binding concentrations of inorganic mercury below 0.5 mmoles/l packed cells had no effect on the K⁺ transport system. In contrast to mercuric chloride, methyl mercuric chloride over similar concentration ranges did not seem to induce a breakdown in the permeability barrier or directly interact with the K⁺/K⁺ exchange but more likely influenced the latter by inhibiting intracellular processes.     

Colorimetric determination of chloride in biological samples by using mercuric nitrate and diphenylcarbazone

A colorimetic method is outlined for the determination of the chloride ion in biological samples (blood serum, plasma, and urine). The present method is based on the quantitative reduction of free mercuric ions by chloride ions. Chloride ions form an indissociable complex with mercuric ions. The remaining free mercuric ions form a purple complex with diphenylcarbazone with an absorption maximum at 550 nm. The reduction of color intensity at 550 nm is directly proportional to chloride concentration in the sample. The linear concentration range in the final reaction mixture was 0–100 μM with a correlation coefficient of −0.9997. The coefficient of variation for the 50 μM chloride ion in the final reaction mixture was 0.9% (n=6). The analyzed value of chloride concentration in the human control serum Accutrol™ Normal (Sigma) was 101±4 mM (mean±SD, n=12). The certified value of chloride in Accutrol Normal by Sigma is 102 mM, with a mean in the range 91–113 mM. This method was applied to the measurement of urinary chloride excretion in experimental rats. During 16-h urine collection, no food was given and rats had free access to purified water. The urinary excretion rate of chloride was 23.6±9.3 μmol/h (mean±SD, n=8) and 126.2±28.0 μmol/h (n=8) for rats fed a normal diet (2.6 g NaCl/kg diet) and a high-salt diet (82.6 g NaCl/kg diet) for 70 d prior to urine collection, respectively. This method is appropriate for low concentrations of chloride in samples or when sample volume is limiting, as in many animal studies such as metabolic urine collection from rats. The U.S. Department of Agriculture, Agricultural Research Service, Northern Plains Area, is an equal opportunity/affirmative action employer and all agency services are available without discrimination. Mention of a trademark or proprietary product does not constitute a guarantee or warranty of the product by the U.S. Department of Agriculture and does not imply its approval to the exclusion of the products that may also be suitable.     

Phosphatases and esterases activity in the brain following an acute sublimate intoxication.

Experiment studies were performed on rats that were administered mercury chloride sublimate with a special gastric cannule in a single 6 mg dose for four consecutive days. As a result of the investigations some changes in the phosphates and esterases activity were revealed. The diminution of AcP, AIP, ATP-ase and AChE activity as well as in the increase in TPP-ase activity in the neurocytes, and also the appearance on NsE activity in many oligodendrocytes was observed. The fall in ATP-ase activity was, above all, observable in cerebral and cerebellar capillaries, which is, in the authors opinion, a manifestation of enzymatic damage to the blood-brain barrier due to a toxic action of mercuric chloride. In the discussion attention was drawn to differences in the degree of enzymatic activity between a mercuric chloride intoxication and that with mercurous chloride, as well as attempt was made to explain the pathogenetic mechanism of this phenomenon. Furthermore, notice was brought to the fact that in the course of sublimate encephalopathy no changes are observed in BuTJ activity.     

Poliovirus-induced Cellular Injury

Protein leakage was used as a quantitative measure of poliovirus-induced cellular injury under suspended cell culture conditions. The requirements for protein leakage were studied in detail and it was established that events early in the infectious cycle which depend upon viral protein synthesis were responsible for cell damage. Extralysosomal β-glucuronidase appeared in infected cells before the onset of protein leakage and release of newly synthesized virus. Hydrocortisone treatment of infected cells resulted in only a slight delay in the release of β-glucuronidase from lysosomes and protein and virus from cells. These results suggest that events associated with poliovirus synthesis trigger the release of lysosomal hydrolases which in turn injure the plasma membrane, allowing cytoplasmic proteins and virus to leak out of the cell.     

In vivo accumulation and effects of mercuric chloride on tissue phosphatases of Notopterus notopterus

Sublethal concentrations of mercuric chloride inhibited the liver, kidney and gill enzymes, acid, alkaline, and glucose-6-phosphatase of the fish Notopterus notopterus, which had been exposed to the heavy metal for 30 days. Higher concentrations produced highly significant (p less than 0.001) inhibition, whereas concentrations that were 1/25th the lethal concentration caused significant (p less than 0.05)/insignificant inhibition. The quantity of mercuric chloride accumulated in tissues correlated with the degree of enzyme inhibition.