Boron-mediated amelioration of copper toxicity in Citrus sinensis seedlings involved reduced concentrations of copper in leaves and roots and their cell walls rather than increased copper fractions in their cell walls.

Little information is available on how boron (B) supplementation affects plant cell wall (CW) remodeling under copper (Cu) excess. 'Xuegan' (Citrus sinensis) seedlings were submitted to 0.5 or 350 µM Cu × 2.5 or 25 µM B for 24 weeks. Thereafter, we determined the concentrations of CW materials (CWMs) and CW components (CWCs), the degree of pectin methylation (DPM), and the pectin methylesterase (PME) activities and PME gene expression levels in leaves and roots, as well as the Cu concentrations in leaves and roots and their CWMs (CWCs). Additionally, we analyzed the Fourier transform infrared (FTIR) and X-ray diffraction (XRD) spectra of leaf and root CWMs. Our findings suggested that adding B reduced the impairment of Cu excess to CWs by reducing the Cu concentrations in leaves and roots and their CWMs and maintaining the stability of CWs, thereby improving leaf and root growth. Cu excess increased the Cu fractions in leaf and root pectin by decreasing DPM due to increased PME activities, thereby contributing to citrus Cu tolerance. FTIR and XRD indicated that the functional groups of the CW pectin, hemicellulose, cellulose, and lignin could bind and immobilize Cu, thereby reducing Cu cytotoxicity in leaves and roots.

The effects of 100 nm pure boron nanoparticles on the primary antioxidant system of Nile tilapia (Oreochromisniloticus).

In this study, the effects of 100 nm boron nanoparticles (B-NPs) on the primary antioxidant status of Nile tilapia were researched via analysis of enzyme activities and related gene expressions. This is a new study which focuses on the relationship between B-NPs and oxidative stress that contribute to the literature in terms of its scope. Fish (n = 15) for each group were exposed to three different concentrations as 5, 25 (n2) and 125 (n3) mg/L during 96 h to see the response of the primary antioxidant system. According to the results, SOD expressions differed in all treatment groups compared to the control group (P < 0.05). CAT expressions were different in 5 and 125 mg/L groups compared to control and 25 mg/L groups (P < 0.05). GPX expressions were only different in 125 mg/L group (P < 0.05). The changes in enzyme activities of SOD and CAT were significantly different in 25 mg/L groups. GPX enzyme activities were not significant (P > 0.05). TBARS concentrations in 25 mg/L group were significantly different from those in the control and 125 mg/L groups (P < 0.05).

Interaction between Boron and Other Elements in Plants.

Boron (B) is an essential mineral nutrient for growth of plants, and B deficiency is now a worldwide problem that limits production of B deficiency-sensitive crops, such as rape and cotton. Agronomic practice has told that balanced B and other mineral nutrient fertilizer applications is helpful to promote crop yield. In recent years, much research has reported that applying B can also reduce the accumulation of toxic elements such as cadmium and aluminum in plants and alleviate their toxicity symptoms. Therefore, the relation between B and other elements has become an interesting issue for plant nutritionists. Here we summarize the research progress of the interaction between B and macronutrients such as nitrogen, phosphorus, calcium, potassium, magnesium, and sulfur, essential micronutrients such as iron, manganese, zinc, copper, and molybdenum, and beneficial elements such as sodium, selenium, and silicon. Moreover, the interaction between B and toxic elements such as cadmium and aluminum, which pose a serious threat to agriculture, is also discussed in this paper. Finally, the possible physiological mechanisms of the interaction between B and other elements in plants is reviewed. We propose that the cell wall is an important intermediary between interaction of B and other elements, and competitive inhibition of elements and related signal transduction pathways also play a role. Currently, research on the physiological role of B in plants mainly focuses on its involvement in the structure and function of cell walls, and our understanding of the details for interactions between B and other elements also tend to relate to the cell wall. However, we know little about the metabolic process of B inside cells, including its interactions with other elements. More research is needed to address the aforementioned research questions in future.

High boron stress leads to sugar beet (Beta vulgaris L.) toxicity by disrupting photosystem â ¡.

This sugar beet acts as a soil remediator in areas where there are high levels of boron (B) in the soil, since it has a high requirement of boron (B) for growth, and has strong resistance to high B levels. Although B toxicity in different plants has been widely researched, little is known about the response of photosystem II (PSII) activity in sugar beet leaves to B toxicity at present. To clarify the growth and photosynthetic physiological response of sugar beet to B toxicity, the effects of different concentrations of H3BO3 (0.05, 1.5, 2.5,3.5 mM) on the growth, photosynthetic characteristics and antioxidant defense system of sugar beet seedlings were investigated by hydroponic experiments. In the present study, high B stress inhibited the growth of sugar beet and significantly decreased the biomass of the plants. There was a remarkable increase in the accumulation of B in the shoots, which affected photosynthesis and decreased the photosynthetic pigments. As B toxicity increased, leaf PSII activities and maximum photochemical efficiency of PSII (Fv/Fm) showed a tendency to decrease; at the same time, the photosynthetic performance index based on absorbed light energy (PIABS) decreased as well. Meanwhile, the energy allocation parameters of the PSII reaction center were changed, the light energy utilization capacity and the energy used for electron transfer were reduced and the thermal dissipation was increased at the same time. Furthermore, B toxicity decreased catalase (CAT) activity, increased peroxidase (POD) and superoxide dismutase (SOD) activities, and increased malondialdehyde (MDA) accumulation. According to the results obtained in this study, high B concentrations reduced the rate of photosynthesis and fluorescence, thus weakened antioxidant defense systems, and therefore inhibited the growth of sugar beet plants. Thus, in high B areas, sugar beet possesses excellent tolerance to high B levels and has a high B translocation capacity, so it can be used as a phytoremediation tool. This study provides a basis for the feasibility of sugar beet resistant to high B environments.

Oxidative Damage to BV2 Cells by Trichloroacetic Acid: Protective Role of Boron via the p53 Pathway.

This study aimed to investigate the neurotoxicity induced by trichloroacetic acid (TCA) and the possible protective mechanisms of boron (B). Mouse BV2 cells were treated with TCA (0, 0.39, 0.78, 1.56, 3.12, 6.25, or 12.5 mmol/L) and B (0, 7.8, 15.6, 31.25, 62.5, 125, 500, or 1,000 mmol/L) for 3 h and 24 h, respectively. Then, reactive oxygen species, and supernatant proinflammatory cytokine and protein levels were analyzed after 24 h of combined exposure. Beyond the dose-dependent decrease in the cellular viability, it clearly increased after B supplementation ( P < 0.05). Moreover, B decreased oxidative damage, and significantly down-regulated IL-6 levels and up-regulated TNF-ß production ( P < 0.05). B also decreased apoptosis via the p53 pathway. The present findings indicated that TCA may induce oxidative damage, whereas B mitigates these adverse effects by decreasing cell apoptosis.

Oxidative Damage to BV2 Cells by Trichloroacetic Acid: Protective Role of Boron via the p53 Pathway / 生物医学与环境科学（英文）

This study aimed to investigate the neurotoxicity induced by trichloroacetic acid (TCA) and the possible protective mechanisms of boron (B). Mouse BV2 cells were treated with TCA (0, 0.39, 0.78, 1.56, 3.12, 6.25, or 12.5 mmol/L) and B (0, 7.8, 15.6, 31.25, 62.5, 125, 500, or 1,000 mmol/L) for 3 h and 24 h, respectively. Then, reactive oxygen species, and supernatant proinflammatory cytokine and protein levels were analyzed after 24 h of combined exposure. Beyond the dose-dependent decrease in the cellular viability, it clearly increased after B supplementation ( P < 0.05). Moreover, B decreased oxidative damage, and significantly down-regulated IL-6 levels and up-regulated TNF-β production ( P < 0.05). B also decreased apoptosis via the p53 pathway. The present findings indicated that TCA may induce oxidative damage, whereas B mitigates these adverse effects by decreasing cell apoptosis.

Molecular and biochemical mechanisms underlying boron-induced alleviation of cadmium toxicity in rice seedlings.

Both cadmium (Cd) contamination and boron (B) deficiency in farmland soils pose a threat to the yield and quality of crops in Southern China. The present study investigated the mechanisms by which B reduces Cd accumulation in rice (Oryza sativa) seedlings. Boron supplementation partially restored the decline in shoot and root biomass caused by Cd treatment (26% and 33%, respectively), with no significant difference between the B+Cd and control groups. We also found that B significantly reduced shoot and root Cd concentrations (by 64% and 25%, respectively) but increased Cd concentration (by 43%) and proportion (from 38% to 55%) in root cell walls. Transcriptome analysis and biochemical tests suggested that B supplementation enhanced lignin and pectin biosynthesis, pectin demethylation, and sulfur and glutathione metabolism. Moreover, B decreased the expression of some Cd-induced transporter-related genes (i.e., HMA2, Nramp1, and several ABC genes). These results indicate that B relieved Cd toxicity and reduced Cd accumulation in rice seedlings by restraining Cd uptake and translocation from root to shoot by improving Cd tolerance and chelation ability. These novel findings would benefit further investigations into how B influences Cd uptake, translocation, detoxification, and accumulation in crops.

Boron reduces aluminum deposition in alkali-soluble pectin and cytoplasm to release aluminum toxicity.

Boron (B) is indispensable for plant growth and has been reported in the mitigation of aluminum (Al) toxicity in different plants. This study focused on the efficacy of B in reducing Al toxicity to trifoliate orange seedlings in a hydroponic experiment. Boron supply had a positive effect on root length and plant growth-related parameters and attenuated Al-induced inhibition of plasma membrane H+-ATPase activity. X-ray photoelectron spectroscopy (XPS) in conjunction with scanning electron microscope-energy dispersive x-ray spectrometer (SEM-EDS) revealed that B reduced Al accumulation in root cell wall, especially on pectin fractions (alkali-soluble pectin), accompanied by suppressing pectin synthesis, pectin methylesterase (PME) activity and PME expression. Furthermore, B application inhibited NRAT1 expression while increased ALS1 expression, indicating restraining Al transport from external cells to cytoplasm and accelerating accelerating vacuolar sequestration. The results were further demonstrated by transmission electron microscope-energy dispersive x-ray spectrometer (TEM-EDS) analysis. Taken together, our results indicated that B mainly promoted the efflux of H+ by regulating the plasma membrane H+-ATPase activity, and reduced the demethylation of pectin to weaken Al binding to carboxyl. More importantly, B alleviated some of the toxic effects of Al by compartmentalizing Al into vacuoles and decreasing the deposition of Al in cytoplasm.

Gibberellic acid-induced generation of hydrogen sulfide alleviates boron toxicity in tomato (Solanum lycopersicum L.) plants.

It was aimed to examine the role of gibberellic acid (GA) induced production of hydrogen sulfide (H2S) in alleviating boron toxicity (BT) in tomato plants. Two weeks after germination, a solution consisting of GA (100 mg L-1) was sprayed once a week for 14 days to the leaves of cv. "SC 2121" of tomato under BT stress (BT; 2.0 mM). Before starting BT treatment, half of the seedlings were retained in a solution containing a scavenger of H2S, 0.1 mM hypotaurine (HT), for 12 h. Boron toxicity led to a substantial decrease in dry biomass, leaf water potential, leaf relative water content, chlorophyll a, chlorophyll b, photosynthetic quantum yield (Fv/Fm), ascorbate (AsA) and glutathione (GSH) in the tomato plants. However, it increased the accumulation of hydrogen peroxide (H2O2), malondialdehyde (MDA), endogenous hydrogen sulfide (H2S), and free proline as well as the activities of catalase, superoxide dismutase and peroxidase. The supplementation of GA mitigated BT by increasing the endogenous H2S, and leaf Ca2+ and K+, and reducing the contents of leaf H2O2, MDA, and B as well as membrane leakage. GA-induced BT tolerance was further enhanced by the supplementation of sodium hydrosulfide (0.2 mM NaHS), an H2S donor. A scavenger of H2S, hypotaurine (0.1 mM HT) was supplied along with the GA and NaHS treatments to assess if H2S was involved in GA-induced BT tolerance of tomato plants. Addition of HT reversed the beneficial effect of GA on oxidative stress and antioxidant defence system by reducing the endogenous H2S without changing L-DES activity, suggesting that H2S participates in GA-induced tolerance to BT of tomato plants.

The analysis of the possibility of using biological tests for assessment of toxicity of leachate from an active municipal landfill.

One of the consequence of municipal waste deposition is the production of landfill leachate. Its volume and composition is determined by numerous factors, including waste composition, landfill age and the volume of precipitation. Leachate may contain a number of mineral and organic compounds, the volume of which must be controlled regularly. One of the methods of determining the toxicity of substances contained in landfill leachate is the use of biological tests, based - among others - on aquatic organisms sensitive to environmental contamination. The purpose of this study was to analyse the possibility of using ecotoxicological tests (supplementing the physical and chemical tests) for the purpose of assessment of landfill leachate toxicity. The tests were conducted at an operating municipal landfill in Stary Sacz (southern Malopolska Region, Poland N: 49°55'33"76, E: 20°65'68'70) from December 2015 to October 2016. The scope of the tests included the analysis of physical and chemical indicators as part of the landfill monitoring process, and also the analysis of additional selected indicators: namely the boron, barium and vanadium content. The selected ecotoxicological tests included tests using Daphnia magna Straus (Cladocera, Crustacea). Leachate tests conducted with the use of physical and chemical indicators have, for nearly twenty years, mainly demonstrated changes related to the age of the used landfill; besides increased boron and barium values, no evident contamination has been found, excluding the case of boron. However, a statistically significant correlation between the B and Ba contents and the amount of precipitation was determined. In two cases, the used biological tests have confirmed the toxicity of the leachate: in January and June 2016. In the same months, the highest and abnormal boron contents were measured, which could cause a toxic effect of leachates.

Arbuscular mycorrhizal fungi alleviate boron toxicity in Puccinellia tenuiflora under the combined stresses of salt and drought.

To investigate the effect of arbuscular mycorrhizal fungi (AMF) on boron (B) toxicity in plants under the combined stresses of salt and drought, Puccinellia tenuiflora was grown in the soil with the inoculation of Funneliformis mosseae and Claroideoglomus etunicatum. After three weeks of treatment, the plants were harvested to determine mycorrhizal colonization rates, plant biomass, as well as tissue B, phosphorus, sodium, and potassium concentrations. The results show that the combined stresses reduced mycorrhizal colonization. Mycorrhizal inoculation significantly increased plant biomass while reduced shoot B concentrations. Mycorrhizal inoculation also slightly increased shoot phosphorus and potassium concentrations, and reduced shoot sodium concentrations. F. mosseae and C. etunicatum were able to alleviate the combined stresses of B, salt, and drought. The two fungal species and their combination showed no significant difference in the alleviation of B toxicity. It is inferred that AMF is able to alleviate B toxicity in P. tenuiflora by increasing biomass and reducing tissue B concentrations. The increase in plant phosphorus and potassium, as well as the decrease in sodium accumulation that induced by AMF, can help plant tolerate the combined stresses of salt and drought. Our findings suggest that F. mosseae and C. etunicatum are potential candidates for facilitating the phytoremediation of B-contaminated soils with salt and drought stress.

Genome-wide identification of barley MCs (metacaspases) and their possible roles in boron-induced programmed cell death.

Developmental processes and stress-induction activate many key proteins in plants such as metacaspase which regulate programmed cell death (PCD). In this study, identification of barley metacaspases and their possible roles upon boron (B)-induction was investigated by using in silico and wet-lab methods. Genome-wide analysis revealed that barley genome harbor ten metacaspases which divided into three groups: Type-I, -I* and -II. Segmental and tandem duplication contributed their expansion. Metacaspase-specific catalytic residues (His and Cys) were found to be altered in HvMC1, 2, and 4, in which His exchanged to Meth or Ala, critical for their activity and substrate selectivity. Cis-acting elements were found to be associated with three main processes: stress response, growth/development, and light response. Digital expression analysis from eight tissues revealed tissue specific metacaspase expressions. In addition, RT-qPCR analysis conducted in appropriate (50 µM) and excess-B (1 and-3 mM) conditions in different time points (3 and 10 days). Toxic level of B caused growth inhibition and chlorosis which appeared at the leaf tips. Also, PCD initiation was detected after 3 days of excess-B exposure. Digital expression and qPCR analysis agreed with each other that HvMC4 expression was significantly increased upon excess-B supplementation. In opposite, HvMC5 was down-regulated in the leaf zones which was another critical B-responsive gene in barley. Hence, HvMC4 and HvMC5 seem to have antagonistic effect during PCD regulation. These results can provide insights for metacaspase functionality in barley, not only limited for B-induction but also various kinds of PCD-causing conditions.

Intake of Boron, Cadmium, and Molybdenum enhances rat thyroid cell transformation.

BACKGROUND: Epidemiologic data in volcanic areas suggest that environmental factors might be involved in the increase of thyroid cancer (TC) incidence. Recent reports indicate that several heavy metals and metalloids are increased in volcanic areas. This study aims to evaluate the combined effect of three of these elements Boron (B), Cadmium (Cd), and Molybdenum (Mo) - all increased in the volcanic area of Mt. Etna, in Italy - on thyroid tumorigenesis in the rat. METHODS: Female Wistar rats prone to develop thyroid tumors by low-iodine diet and methimazole treatment received ad libitum drinking water supplemented with B, Cd, and Mo at concentrations in the range found in the urine samples of residents of the volcanic area. At 5 and 10 months animals were euthanized, and their thyroid analysed. Statistical analysis was performed with a 2-way unpaired t-test. RESULTS: No toxic effect of the three elements on the growth of the animals was observed. A significant increase of histological features of transformation was observed in thyroid follicular cells of rats treated with B, Cd, and Mo compared with those of control group. These abnormalities were associated with decreased iodine content in the thyroid. CONCLUSIONS: This study provides the evidence that slightly increased environmental concentrations of B, Cd, and Mo can accelerate the appearance of transformation marks in the thyroid gland of hypothyroid rats.

Tavaborole, a Novel Boron-Containing Small Molecule Pharmaceutical Agent for Topical Treatment of Onychomycosis: II. Prenatal and Postnatal Developmental Toxicity and Maternal Function Study.

Tavaborole is a topical antifungal agent approved by the US Food and Drug Administration for the treatment of toenail onychomycosis. The effects of tavaborole on gestation, parturition (delivery, labor), offspring development, and survival during the perinatal and postnatal periods were assessed in mated female rats. Females (F0 generation) were administered single daily oral (gavage) doses of 15, 60, or 100 mg/kg/d from gestation day 6 through lactation day 20. The females were allowed to deliver naturally and rear their offspring until lactation day 21, at which time the F0 females were euthanized. One male and female from each litter were selected (F1 generation) and retained for assessments, including growth, neurobehavior, fertility, and their ability to produce an F2 generation. Reproductive and offspring parameters were determined for the F1 and F2 generations, as applicable. F1 females and F2 pups were euthanized on postnatal day 7. In the F0 females, decreased activity was observed in the 100 mg/kg/d dose group. Excess salivation was observed in the 60 and 100 mg/kg/d dose groups (slight to moderate), however, this finding was not considered adverse. There were no tavaborole-related effects on the growth, viability, development, neurobehavioral assessments, or reproductive performance of the F1 generation. Survivability and mean body weight of the F2 pups were unaffected. The no observed adverse effect level (NOAEL) for maternal toxicity (F0 generation) was 60 mg/kg/d, based on the decreased activity observed in the 100 mg/kg/d dose group. The NOAEL for the offspring effects was ≥100 mg/kg/d, based on the lack of test article-related changes.

Histological evaluation of the effects of borax obtained from various sources in different rat organs / Evaluación histológica de los efectos del borax obtenido de diversas fuentes en diferentes órganos de rata

Boron is an essential element for life and intake via different sources into the body. Because effects of boron and compounds on the body has not been studied enough especially in tissue level, we planned this study to evaluate the effects of borax the most intaken form of boron compound on different intraabdominal organs histologically and also clinically. 42 male rats divided into equal 7 groups and different toxicological doses consistent with its LD50 dose (5000 mg/kg/d) were administered by gavage except control and sham groups. In the study, 2 different kinds of borax one of which was produced for research and the other for agriculture but the same formulation, were used and their effects were also compared. As a result it was found that borax did not cause any histological changes in kidney, large intestine, liver and stomach in lower doses. But if doses were increased, a slightly inflammatory cell migration was detected without clinical signs in liver and large intestine. However, when a single very high dose of borax was administered, very high edema, inflammatory cell migration and neovascularization was observed and clinically 2 out of 6 rats died within 5 hours. We suggested that very high dose intake of borax may cause sudden death and also during long periods and higher dose intake may pave the way of inflammatory bowel diseases. At the same time, in boron related studies we advice that the kind of boron and also their source should be evaluated carefully and the most suitable compound should be chosen in case of faulty results.

El boro es un elemento esencial para la vida e ingresa a través de diferentes fuentes al cuerpo. Dado que los efectos del boro y sus compuestos en el cuerpo no se han estudiado lo suficiente, especialmente a nivel tisular, se planificó este estudio para evaluar sus efectos y la forma de consumo más común del compuesto de boro sobre diferentes órganos intraabdominales a nivel histológico y clínico. Cuarenta y dos ratas macho divididas en 7 grupos, con diferentes dosis toxicológicas de acuerdo con su dosis DL50 (5000 mg/kg/d) administradas por sonda, excepto en los grupos control y simulado. En el estudio fueron usados 2 tipos diferentes de boro, uno producido para la investigación y el otro para la agricultura, pero de la misma formulación, y sus efectos fueron comparados. Se encontró que el boro no causó cambios histológicos en el riñón, intestino grueso, hígado y estómago en dosis bajas. Sin embargo, al aumentar la dosis, se detectó una leve migración de células inflamatorias, sin signos clínicos, en el hígado e intestino grueso. Por otra parte, cuando se administró una sola dosis muy alta de boro, se observó un amplio edema, migración de células inflamatorias y neovascularización; clínicamente 2 de 6 ratas murieron dentro de 5 horas. Sugerimos que la ingesta de dosis muy altas de bórax pueden causar la muerte súbita, además la ingesta de dosis altas y durante periodos de tiempo prolongado puede causar enfermedades inflamatorias del intestino. Es recomendable que en los estudios relacionados con el boro, el tipo de boro así como su fuente sean evaluados cuidadosamente, eligiendo el compuesto más adecuado en caso de resultados erróneos.

Metals and female reproductive toxicity.

Research into occupational exposure of metals and consequences of reproductive systems has made imperative scientific offerings in the preceding few decades. Early research works focused on possible effects on the reproductive functions rather than the complete reproductive health of the woman. Later, it was realized that metals, as reproductive toxins, may also induce hormonal changes affecting other facets of reproductive health such as the menstrual cycle, ovulation, and fertility. Concern is now shifting from considerations for the pregnant woman to the entire spectrum of occupational health threats and thus reproductive health among women.

cDNA-AFLP analysis reveals the adaptive responses of citrus to long-term boron-toxicity.

BACKGROUND: Boron (B)-toxicity is an important disorder in agricultural regions across the world. Seedlings of 'Sour pummelo' (Citrus grandis) and 'Xuegan' (Citrus sinensis) were fertigated every other day until drip with 10 µM (control) or 400 µM (B-toxic) H3BO3 in a complete nutrient solution for 15 weeks. The aims of this study were to elucidate the adaptive mechanisms of citrus plants to B-toxicity and to identify B-tolerant genes. RESULTS: B-toxicity-induced changes in seedlings growth, leaf CO2 assimilation, pigments, total soluble protein, malondialdehyde (MDA) and phosphorus were less pronounced in C. sinensis than in C. grandis. B concentration was higher in B-toxic C. sinensis leaves than in B-toxic C. grandis ones. Here we successfully used cDNA-AFLP to isolate 67 up-regulated and 65 down-regulated transcript-derived fragments (TDFs) from B-toxic C. grandis leaves, whilst only 31 up-regulated and 37 down-regulated TDFs from B-toxic C. sinensis ones, demonstrating that gene expression is less affected in B-toxic C. sinensis leaves than in B-toxic C. grandis ones. These differentially expressed TDFs were related to signal transduction, carbohydrate and energy metabolism, nucleic acid metabolism, protein and amino acid metabolism, lipid metabolism, cell wall and cytoskeleton modification, stress responses and cell transport. The higher B-tolerance of C. sinensis might be related to the findings that B-toxic C. sinensis leaves had higher expression levels of genes involved in photosynthesis, which might contribute to the higher photosyntheis and light utilization and less excess light energy, and in reactive oxygen species (ROS) scavenging compared to B-toxic C. grandis leaves, thus preventing them from photo-oxidative damage. In addition, B-toxicity-induced alteration in the expression levels of genes encoding inorganic pyrophosphatase 1, AT4G01850 and methionine synthase differed between the two species, which might play a role in the B-tolerance of C. sinensis. CONCLUSIONS: C. sinensis leaves could tolerate higher level of B than C. grandis ones, thus improving the B-tolerance of C. sinensis plants. Our findings reveal some novel mechanisms on the tolerance of plants to B-toxicity at the gene expression level.

Boron-based inhibitors of acyl protein thioesterases 1 and 2.

Ras proteins are of importance in cell proliferation, and hence their mutated forms play causative roles in many kinds of cancer in different tissues. Inhibition of the Ras-depalmitoylating enzyme acyl protein thioesterases APT1 and -2 is a new approach to modulating the Ras cycle. Here we present boronic and borinic acid derivatives as a new class of potent and nontoxic APT inhibitors. These compounds were detected by extensive library screening using chemical arrays and turned out to inhibit human APT1 and -2 in a competitive mode. Furthermore, one of the molecules was demonstrated to inhibit Erk1/2 phosphorylation significantly.

[Effect of drinking boron on microtructure of adrenal gland in rats].

OBJECTIVE: The effects of drinking boron exposure on the mass, organ indexes and structure of adrenal gland were studied in the paper. Methods 192 Sprague-Dawley rats (28 +/- 2 days) with no bacteria infecting were divided into six groups (n = 32, male = female) randomly. Treated rats drunk the distilled water which supplemented with boron of 0, 40, 80, 160, 320 and 640 mg/L, respectively, for 60 days. At the 30th and the 60th day of experiment, 16 rats (n = 8, male = female) of each group were selected and made into narcosis with 10% Chloral Hydrate. The adrenal glands were obtained, weighted and fixed after dissection, then the samples were made into paraffin sections, stained with HE stain and chromaffin, observed and photographed by Olympus CH-30 microphotograph system. RESULTS: Compared with control group, the average mass of adrenal gland of male rats in each experiment group decreased significantly or most significantly at the 30th day of experiment (P < 0.05 or P < 0.01), but the index of adrenal gland of male rats in the group of 640 mg/L boron at 60th day of experiment increased significantly (P < 0.05). Under the microscope, the microstructure of adrenal gland of rats in the group of 40 mg/L boron were better obviously than control group, and the numbers of chromaffin granules in chromaffin cell increased obviously. The histopathological changes of different degree could be observed in the group of 80 to 640 mg/L boron, and they became remarkable with the boron supplementation. By comparative observation, the damage of cells in adrenal medulla appeared ahead of them in adrenal cortex, and the pathological change of adrenal gland in male rats were obvious than female rats. CONCLUSION: Drinking supplemented with 40 mg/L boron could prompt the structure of adrenal gland in rats, but could cause different degree damage, or even obvious toxic effect when the concentration of boron supplementation in drinking from 80 to 640 mg/L.

Influence of physico-chemical parameters of the aquatic medium on germination of Eichhornia crassipes seeds.

The germination of seeds of Eichhornia crassipes in locations distant from the foci of infestation may be a means of dispersal of this invasive plant. Nonetheless, no modern studies have examined the influence of single components on germination, although the influence of temperature, oxygen and redox potential was examined in earlier studies. The effects of pH, conductivity, nitrate, phosphate, potassium, calcium, iron and boron on germination of E. crassipes were determined in seed germination tests. The results showed that external input of nutrients influences germination, since neither pH nor conductivity alone had any effect, but there was a significant increase in germination in growth media containing phosphorus at 3.95 mg·l(-1) (P/L; 95.5%) and boron at 10 mg·l(-1) (B/L; 97.5%); at higher concentrations, the latter was toxic. These findings contribute to knowledge of factors controlling the germination of E. crassipes seeds. Consequently, E. crassipes seeds would find very good conditions for germination in water classified as hypereutrophic, which may play a decisive role in expansion of this plant.