Interaction of Mercuric Ions with Different Marine Algal Species

The use of different seaweeds such as Sargassum sp., Turbinaria conoides, and Ulva sp. in removing mercury(II) from aqueous solutions were investigated. The initial experimental runs, conducted at different equilibrium pH conditions, demonstrated that brown seaweeds outperformed green seaweed in Hg(II) biosorption at all pH conditions. In particular, at pH 5, maximum biosorption capacities of 170.3 and 145.8 mg/g were recorded for the brown seaweeds T. conoides and Sargassum sp., respectively, compared with 138.4 mg/g for the green seaweed Ulva sp. Isotherm data were modeled and interpreted using the Langmuir, Freundlich, Redlich-Peterson, and Toth models, with the latter described the Hg(II) isotherms with high correlation coefficients and low % error values. The kinetic data indicate the rapidity of the biosorption process, with the equilibrium achieved within 90 min. Several models, including the Elovich, pseudo-first-order, and pseudo-second-order models, were examined for their suitability with the present data; the correlation coefficient and % error values, along with better prediction of equilibrium uptake values, favored the pseudo-first-order model. The desorption experiments were highly successful for T. conoides biomass with 0.05 M HCl, whereas for the other two seaweeds, 0.05 M HCl resulted in high biomass weight loss. Reusing T. conoides biomass in three successive sorption-desorption cycles resulted in only 8.8% reduction in Hg(II) biosorption capacity compared with its original uptake.     

Plant Protection with Inorganic Ions

Gradients of salts of the specific ion repellents for Meloidogyne incognita -- NH₄⁺, K⁺, Cl⁻, and NO₃⁻ -- have been demonstrated to shield tomato roots from infestation in soil. The strategy of these greenhouse experiments was to interpose a salt barrier in a soil column between the plant roots and the nematodes. The relative effectiveness of the salts as a barrier to infective second-stage juveniles in a sandy loam was NH₄NO₃, NH₄Cl > KNO₃ > KCl. Some of these ions are beneficial to plant growth, and the results suggest that a new environmentally tolerable means of plant protection is possible.     

Biochemical Oxidation of Reduced-form Cytochrome c by Mercuric Ions

A simple method has been developed for DNA isolation from purified chloroplasts of Marchantia polymorpha L. (liverwort) cell suspension cultures. Purified chloroplasts exhibited ribulose-bisphosphate carboxylase activity comparable to that of Fraction 1 protein obtained from Nicotiana tabacum. Fraction 1 protein isolated from purified chloroplasts clearly showed large and small subunits when subjected to isoelectric focussing. These results indicate that the purified chloroplasts are intact. DNA isolated from purified chloroplasts showed a covalently closed circular form, and restriction endonuclease digestions of the chloroplast DNA showed clear fragmentation indicating that the DNA was sufficiently free from those of other organelles.     

Dietary Supplementation of Selenium in Inorganic and Organic Forms Differentially and Commonly Alters Blood and Liver Selenium Concentrations and Liver Gene Expression Profiles of Growing Beef Heifers

In geographic regions where selenium (Se) soil concentrations are naturally low, the addition of Se to animal feed is necessary. Even though it is known that Se in grass and forage crops is primarily present in organic forms (especially as L-selenomethionine, L-selenocystine, and L-selenocystathionine), the feeding of Se in the naturally occurring organic selenium (OSe) compounds produces higher blood and tissue Se levels than the inorganic Se (ISe) salts, and that animal metabolism of OSe and ISe is fundamentally different. Se is commonly added in inorganic form as sodium selenite to cattle feeds because it is a less expensive source of supplemental Se then are OSe forms. A trial was conducted with growing cattle to determine if the addition of OSe versus ISe forms of Se in beef cattle feed produces differences in hepatic gene expression, thereby gaining insight into the metabolic consequence of feeding OSe versus ISe. Thirty maturing Angus heifers (261?±?6 days) were fed a corn silage-based diet with no Se supplementation for 75 days. Heifers (body weight?=?393?±?9 kg) then were randomly assigned (n?=?10) and fed Se supplements that contained none (control) or 3 mg Se/day in ISe (sodium selenite) or OSe (Sel-Plex®) form and enough of a common cracked corn/cottonseed hull-based diet (0.48 mg Se/day) to support 0.5 kg/day growth for 105 or 106 days. More Se was found in jugular whole blood and red blood cells and biopsied liver tissue of ISe and OSe treatment animals than control animals, and OSe animals contained more Se in these tissues than did ISe. Microarray and bioinformatic analyses of liver tissue gene expression revealed that the content of at least 80 mRNA were affected by ISe or OSe treatments, including mRNA associated with nutrient metabolism; cellular growth, proliferation, and immune response; cell communication or signaling; and tissue/organ development and function. Overall, three Se supplement-dependent gene groups were identified: ISe-dependent, OSe-dependent, and Se form-independent. More specifically, both forms of supplementation appeared to upregulate mitochondrial gene expression capacity, whereas gene expression of a protein involved in antiviral capacity was downregulated in ISe-supplemented animals, and OSe-supplemented animals had reduced levels of mRNA encoding proteins known to be upregulated during oxidative stress and cancerous states.     

Mercury Toxicity and the Mitigating Role of Selenium

Mercury is a well-known environmental toxicant, particularly in its most common organic form, methylmercury. Consumption of fish and shellfish that contain methylmercury is a dominant source of mercury exposure in humans and piscivorous wildlife. Considerable efforts have focused on assessment of mercury and its attendant risks in the environment and food sources, including the studies reported in this issue. However, studies of mercury intoxication have frequently failed to consider the protective effects of the essential trace element, selenium. Mercury binds to selenium with extraordinarily high affinity, and high maternal exposures inhibit selenium-dependent enzyme activities in fetal brains. However, increased maternal dietary selenium intakes preserve these enzyme activities, thereby preventing the pathological effects that would otherwise arise in their absence. Recent evidence indicates that assessments of mercury exposure and tissue levels need to consider selenium intakes and tissue distributions in order to provide meaningful risk evaluations.     

Pregnancy Alters Renal and Blood Burden of Mercury in Females

The concentrations of copper and zinc in the tissues of alcohol-addicted people can significantly correlate with the variables describing their mental state. Studies on the homeostasis of zinc in alcohol-dependent patients have often been characterized by low hypozincemia detection. This may be caused by a low content of zinc in blood serum (1%) compared to the average zinc level in the body. Unfortunately, most authors have identified extracellular zinc in their studies. In the available literature, data on the level of copper in patients suffering from alcohol dependence are inconsistent. Our study included 100 alcohol-addicted patients (the study group) and 50 healthy subjects (the control group). Mental state was measured using appropriate psychometric scales. We used inductively coupled plasma mass spectrometry (ICP-MS) to determine copper and zinc content. Our results confirm the purposefulness of the use of zinc concentration in erythrocytes as a diagnostic parameter for low zinc status in alcohol-dependent patients. Alcohol-dependent patients with reduced concentrations of zinc in erythrocytes/copper in blood plasma differed significantly from alcohol-dependent patients with normal concentrations in terms of clinical parameters. With regard to zinc in blood plasma and copper in erythrocytes, this situation has not been found. The clinical symptoms of hypozincemia and copper deficiency in patients addicted to alcohol usually relate to disorders in central nervous system functioning, and they result in a decreased quality of physical and mental life.     

Selenium Supplementation Alters Gene Expression Profiles Associated with Innate Immunity in Whole-Blood Neutrophils of Sheep

Footrot (FR) is a common, contagious bacterial disease of sheep that results in lameness and significant economic losses for producers. We previously reported that sheep affected with FR have lower whole-blood (WB) selenium (Se) concentrations and that Se supplementation in conjunction with routine control practices accelerates recovery from FR. To determine whether oral Se-yeast administered at supranutritional levels (>4.9 mg Se/week) alters the ability of sheep to resist or recover from FR infection, 60 ewes with and 60 ewes without FR were drenched once weekly for 62.5 weeks with 0, 4.9, 14.7, or 24.5 mg organic Se-yeast (30 ewes per treatment group). Footrot prevalence and severity were measured at 0, 20, 28, 40, and 60 weeks of Se supplementation. Genomic expression of eight WB-neutrophil genes for selenoproteins and seven WB-neutrophil genes for proteins involved in innate immunity was determined at the end of the treatment period using SYBR Green and quantitative polymerase chain reaction methodology. Supranutritional Se-yeast supplementation successfully increased Se status in sheep but did not prevent FR. Supranutritional Se-yeast supplementation increased WB-neutrophil expression of genes involved in innate immunity: l-selectin, interleukin-8 receptor, and toll-like receptor 4, which were or tended to be lower in ewes affected with FR. Furthermore, supranutritional Se-yeast supplementation altered the expression of selenoprotein genes involved in innate immunity, increasing selenoprotein S and glutathione peroxidase 4 and decreasing iodothyronine deiodinases 2 and 3. In conclusion, supranutritional Se-yeast supplementation does not prevent FR, but does alter WB-neutrophil gene expression profiles associated with innate immunity, including reversing those impacted by FR.     

Repetitive Microstimulation Alters the Cortical Representation of Movements in Adult Rats

In order to examine the effects of repetitive stimulation on functional cortical organization, standard intracortical microstimulation (ICMS) techniques were used to generate maps of movement representations in motor cortex of rat. After identification of caudal and rostral forelimb fields and adjacent vibrissae and neck fields, one or more representational borders were defined in greater detail. Then a microelectrode was introduced into one of these representational fields, and ICMS current pulses were delivered at a rate of 1/sec for 1 to 3 hr. Following repetitive ICMS, significant changes in movement representations were observed using current levels that were either suprathreshold or subthreshold for evoking the site-specific movement. Electromyographic activity could be evoked at suprathreshold and near-threshold current levels, but not at the subthreshold current levels used here. Significant border shifts ranged from 210 to 670 μm. In each case in which shifts occurred, there appeared to be expansion of the movement represented at the repetitively stimulated site. The effects were progressive and reversible. These results suggest that at least under these unusual experimental circumstances, large representational changes can be generated very rapidly within motor cortex in the absence of any evident peripheral feedback.     

Hormone Therapy Alters the Composition of the Vaginal Microflora in Ovariectomized Rats

The aim of the present study was to evaluate the alterations that may take place in the bacterial genital tract flora in the absence of ovarian hormones. The role of hormone replacement therapy was also assessed. For this purpose, various bacteria were identified from the vaginal flora of ovariectomized and sham operated female rats, following the Bergey’s manual criteria. The data of this study showed that substantial differences exist in the vaginal bacterial microflora between ovariectomized and normal cyclic rats. Ovariectomy was associated with a lower total bacterial load that may be due mainly to the absence of Lactobacillus. Anaerobic bacteria were also absent. Streptococcus and Enterococcus were also not favored in an environment lacking the ovarian hormones. In contrast, C. perfringens, Bacteroides, S. epidermidis, and S. aureus were detected in high numbers in ovariectomized rats. In terms of the impact of hormone replacement therapy on vaginal flora, only estradiol (EE2) restored Lactobacillus levels in ovariectomized rats, whereas all hormonal schemes used brought Streptococcus, Clostridium lec (−), and C. perfringens, the spore and vegetative forms, close to those detected in normal cyclic female rats. In conclusion, ovarian hormones appeared to be regulatory factors that favor the presence of a broad variety of bacteria, which are members of the normal genital tract flora. On the other hand, ovariectomy modifies the vaginal microbial profile, and hormone replacement therapy based mainly on schemes containing EE2 could alleviate this disturbance.     

汞与硒在不同汞暴露水平地区猪肝脏和肾脏蛋白质中的分布

通过对贵州万山汞污染地区及北京地区猪肝脏和肾脏组织上清液进行凝胶过滤色谱分离(SephadexG 10 0 ) ,随后用原子荧光法测定它们蛋白质组分中汞和硒的含量 ,研究在汞暴露水平不同状态下微量元素汞和硒在动物体蛋白质分子水平上的分布 .发现这两个地区猪肝脏和肾脏组织上清液蛋白质组分中汞和硒的分布模式有明显差异 .贵州万山汞污染地区猪肝脏上清液中汞浓度比北京地区高 ,硒浓度也相应高 ,且前者与高分子量和低分子量蛋白结合的硒均明显高于后者 ;而北京地区猪肝脏上清液中的硒主要以与高分子量蛋白结合的形式存在 .贵州汞污染地区猪肝脏上清液中汞主要与高分子量蛋白结合 ,而北京地区猪肝脏上清液中汞则分布较为均匀 .贵州万山地区猪肾脏上清液中 ,含硒峰在高分子量蛋白区和低分子量区都有分布 ;而北京地区猪肾脏上清液中 ,硒则主要集中分布于高分子量蛋白范围 .这两个地区猪肾脏上清液中都有分子量约为 11kD的金属硫蛋白 (MT)存在 ,北京地区猪肾脏上清液中汞主要以与金属硫蛋白结合的形式出现 ,而贵州万山地区猪肾脏上清液中的汞除与金属硫蛋白结合外 ,尚有相当大部分是以与高分子量蛋白结合的形式存在 .研究结果表明 ,由于这两个地区汞暴露水平的差异 ,不仅使这两地区猪肝、肾上清液中的汞与硒含量     

螺旋藻富集和转化硒研究进展

无机硒的生物有机化是开发有机硒的合理途径。硒有机化生物载体有酵母、大蒜、螺旋藻、蜜蜂等。螺旋藻富集和转化硒具有良好的产业化前景,就藻种的选择、培养条件的优化、硒添加浓度和方法等方面的研究进展进行了综述。     

Valproic Acid Alters GnRH-GABA Interactions in Cycling Female Rats

Summary of the aims Women with epilepsy using antiepileptic drug valproic acid (VPA) often suffer from reproductive endocrine disorders, menstrual disorders and polycystic ovaries. Valproic acid exerts anticonvulsive effects via gamma amino butyric acid (GABA) neurotransmitter system, which also acts as a neurochemical regulator of gonadotropin-releasing hormone (GnRH) neurons and suggests possibility of valproic acid mediated interruption in gonadotropin releasing hormone pulse generator in hypothalamus. The aim of this study was to investigate the effects of valproic acid treatment on the expression of gonadotropin releasing hormone, gamma amino butyric acid and polysialylated form of neural cell adhesion molecule (PSA-NCAM) a marker of neuronal plasticity in the median preoptic area (mPOA) and median eminence-arcuate (ME-ARC) region having GnRH neuron cell bodies and axon terminals, respectively. Methods Three-month-old virgin Wistar strain female rats received VPA (i.p.) at a dose of 300 mg/kg once a day for 12 weeks; control group received an equivalent volume of vehicle. GnRH, GABA and PSA-NCAM expressions were studied by immunohistofluorescence technique from mPOA and ME-ARC region of hypothalamus. Ovarian histology was also studied using Mayer’s Haematoxylin-Eosin staining method. Results GnRH and PSA-NCAM staining was much higher in mPOA and ME-ARC region from vehicle treated control proestrous rats, whereas VPA treatment significantly enhanced GABA expression, and reduced both GnRH and PSA-NCAM expression. Mayer’s Haematoxylin-Eosin staining of mid-ovarian sections revealed significantly higher number of ovarian follicular cysts in VPA treated rats. Conclusions Our findings of alterations in GnRH and GABA expression and GnRH neuronal plasticity marker PSA-NCAM as well as changes in ovarian histology suggest that treatment with VPA disrupts hypothalamo-hypophyseal-gonadal axis (HPG) at the level of GnRH pulse generator in hypothalamus.     

脱金属硫蛋白与二价汞离子的络合作用及构象研究

用圆二色谱研究兔肝锐金属硫蛋白的两个亚型ａｐｏ－ＭＴ１、ａｐｏ－ＭＴ２与Ｈｇ＾２＋在不同分子数比和ｐＨ值下的络合规律。发现：（１）在ｐＨ２下与Ｈｇ＾２＋重组ＭＴｓ的ＣＤ谱特征峰是３０４ｎｍ（＋）,２６０ｎｍ（－）,２５０ｎｍ（＋）。络合Ｈｇ＾２＋的数目ｎ远远超过７。任何ｐＨ值下过量Ｈｇ＾２＋的存在都将破坏ＭＴｓ的正常构象。ｐＨ值对形成和维持ＭＴｓ稳定构象的影响很大,当ｐＨ≥４．９时,ａｐｏ－ＭＴｓ     

The Uptake of Inorganic Ions by Plant Leaves

A technique for estimating the gross uptake of ions by plantleaves is described. Uptake of strontium-89 and caesium-137from droplets applied to plant leaves was greatly affected bythe humidity of the air, the effect being markedly dependenton the initial concentration of the solution. Uptake was greaterin light than in darkness; the effect of temperature was relativelysmall. The percentage uptake of the nuclides was reduced only to arelatively small extent as the concentration of carrier ionwas increased. This was in marked contrast to the situationwhen leaves were fully immersed in solution. ¹³⁷Cs was takenup to a greater extent than iodine, phosphate, or sulphate.The role of exchange and of fixed negative charges in uptakeis discussed.     

蒙药孟根乌苏-18 味丸、孟根乌苏炮制品的肝肾毒性作用研究

目的:对比研究孟根乌苏(水银)-18味丸、孟根乌苏(水银)炮制品与硫化汞、氯化汞、氯化亚汞的肝肾毒性作用。方法:将Wistar雄性大鼠,根据体重随机分为正常对照组、孟根乌苏-18味丸低、高剂量组(0.29,2.9 g·kg~(-1)·d~(-1))、孟根乌苏-18味丸简化方组(0.26 g·kg~(-1)·d~(-1))、孟根乌苏炮制品低、高剂量组(0.033,0.33 g·kg~(-1)·d~(-1))、硫化汞组(17.39 mg·kg~(-1)·d~(-1))、氯化汞组(4.06 mg·kg~(-1)·d~(-1))、氯化亚汞组(35.3 mg·kg~(-1)·d~(-1)),共9组,每组6只。各组大鼠适应7天后,灌胃给药7天后分别检测肝肾功能,肝肾组织形态学变化,并用电感耦合等离子体发射光谱仪(ICP-OES)和电感耦合等离子体质谱仪(ICP-MS)法测肾汞蓄积量,原位末端标记(TUNEL)法测肾细胞凋亡,免疫组化法测肾Ⅲ型胶原蛋白表达,实时荧光定量PCR(Real-Time-PCR)法检测肾脏MT-1、MT-2基因表达的变化。结果:在实验过程中,氯化亚汞组4只大鼠死亡,因此未对实验数据进行统计。大鼠连续7天给药后,药物对各组大鼠肝、肾功能并无影响。肝脏和肾脏病理检查结果表明,孟根乌苏-18味丸和孟根乌苏炮制品低剂量组肝细胞肿胀变性程度较轻,肾小球轻度肥大,肾小管上皮轻度肿胀变性,孟根乌苏-18味丸和孟根乌苏炮制品高剂量组以及硫化汞组大鼠肝脏、肾脏均出现了一定的病理变化,而氯化汞、氯化亚汞组大鼠肝肾病理变化更显著。与正常对照组和孟根乌苏炮制品低剂量组相比,氯化汞组大鼠肾汞蓄积量显著升高(P0.01);硫化汞、氯化汞组大鼠肾细胞凋亡率和Ⅲ型胶原蛋白表达显著升高(P0.01);与正常对照组比较,氯化汞组大鼠肾组织中MT-1和MT-2 m RNA表达显著升高(P0.01,P0.05);氯化汞组大鼠肾组织中MT-1表达显著高于孟根乌苏炮制品低剂量组(P0.01)。结论:临床常用量的孟根乌苏-18味丸和孟根乌苏炮制品肝肾毒性要远低于氯化亚汞、氯化汞。     

Kinetics of Mercury Reduction by Serratia marcescens Mercuric Reductase Expressed by Pseudomonas putida Strains

Mercury (Hg) resistance is widespread among microorganisms and is based on the intracellular transformation of Hg(II) to less toxic elemental Hg(0). The use of microbial consortia to demercurize polluted wastewater streams and environments has been demonstrated. To develop efficient and versatile microbial cleanup strategies requires detailed knowledge of transport and reaction rates. This study focuses on the kinetics of the key enzyme of the microbial transformation, e.g., the mercuric reductase (MerA) under conditions closely resembling the cell interior. To this end, previously constructed and characterized Pseudomonas putida strains expressing MerA from Serratia marcescens were applied. Of the P. putida strains considered in this study P. putida KT2442::mer73 constitutively expressing broad spectrum mercury resistance (merTPAB) yielded the highest mercuric reductase (MerA) activity directly after cell disruption. MerA in the raw extract was further purified (about 100 fold). Reduction rates were measured for various substrates (HgCl₂, Hg₂SO₄, Hg(NO₃)₂ and phenyl mercury acetate) up to high concentrations dependent on the purification grade. In all cases, a pronounced substrate inhibition was found. The kinetic constants determined for the cell raw extract are in agreement with those measured for intact cells. However, the rate data exhibit reduced affinity and inhibition with rising purification grade (specific activity). Therefore, the findings seemingly point to reactions preceding the catalytic reduction. Based on simplified assumptions, a kinetic model is suggested which reasonably describes the experimental findings and can advantageously be applied to the bioreactor design.