Transition metal-saccharide chemistry: d-glucose complexes of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II)

Metal complexes of d-glucose (d-Glc) from large cation containing dibromo-dichloro salts of dipositive metals [NEt₄]₂[MBr₂Cl₂] (M = Mn, Co, Ni, Cu and Zn) and the disodium salt of glucose were synthesized from a MeOH:MeCN mixture. The complexes were characterized by UV-vis absorption, circular dichroism, IR and proton magnetic resonance spectroscopies, and by elemental analysis, and were found to be Na[M(d-Glc)(OMe)Cl]. Cyclic voltammetric studies of these complexes, in the acidic to neutral pH range, indicated no dissociation, even in highly acidic conditions.This paper is dedicated to Professor Richard H. Holm (Harvard University) on the occasion of his 60th birthday.     

北京石灰性草甸土冬小麦营养元素生物循环的特点与锰、锌肥效应

 本文用盆钵试验研究京郊石灰性草甸土冬小麦养分生物循环的结果表明：小麦对不同养分吸收、携出和归还数量的差异很大。根据随籽粒携出和以根茬归还的比例特点,可将养分划分为三种类型：1)低归还高携出型(N、P、K);2)低携出高归还型(Ca、Fe);3)中归还中携出型(Mg、Mn、Cu、Zn)。施锰增加植株对氮和锰的吸收及钾和锰随籽粒的携出;施锌则降低植株对锰的吸收和随籽粒携出的钾、钙、镁、铁、锰量。锰肥和锌肥有拮抗作用。     

Effects of manganese toxicity on leaf CO2 assimilation of contrasting common bean genotypes

Parameters related to leaf photosynthesis were evaluated in three genotypes of common bean ( Phaseolus vulgaris L.) with contrasting tolerance to Mn toxicity. Two short-term studies in solution culture were used to assess the effect of excess Mn on CO₂ assimilation in mature and immature leaves. Mn toxicity decreased total chlorophyll content only in immature leaves, with a consequent reduction of leaf CO₂ assimilation. Mature leaves that showed brown speckles characteristic of Mn toxicity, did not suffer any detriment in their capacity to assimilate CO₂, at least in a 4-day experiment. Stomatal conductance and transpiration were not affected by the presence of high levels of Mn in leaf tissue. Lower stomatal conductance and transpiration rates were observed only in leaves with advanced chlorosis. Differences among genotypes were detected as increased chlorosis in the more sensitive genotype ZPV-292, followed by A-283 and less chlorosis in the tolerant genotype CALIMA. Since CO₂ assimilation expressed per unit of chlorophyll was not different between high-Mn plants and control plants, we conclude that the negative effect of Mn toxicity on CO₂ assimilation can be explained by a reduction in leaf chlorophyll content.     

Mn、Zn和Fe对醉马草内生真菌共生体麦角酰胺和麦角新碱含量的影响

该研究通过温室砂培试验,考察了不同浓度Mn、Zn和Fe处理对醉马草内生真菌共生体麦角酰胺和麦角新碱含量的影响,以明确共生体产碱所需3种微量元素的最佳浓度范围。结果表明:(1)在短时间(3周)处理下,共生体麦角酰胺和麦角新碱含量均在Mn~(2+)浓度为5.0mmol·L~(-1)时达到最大值,且显著高于其余Mn~(2+)浓度梯度;在较长时间(6、9周)处理下,其麦角酰胺含量在Mn~(2+)浓度为5.0mmol·L~(-1)时最大但增幅不明显,麦角新碱在对照(0.01mmol·L~(-1) Mn~(2+))处理下积累量达到最大,且显著高于其余处理。(2)共生体麦角酰胺含量在处理时间为3、6和9周时,Zn~(2+)处理均在7.0mmol·L~(-1)下达到最大值,且处理3周的含量显著高于其余处理时间;其麦角新碱在3个处理时间下均于Zn~(2+)浓度为21.0mmol·L~(-1)时达到最大值。(3)在不同处理时间下,共生体麦角酰胺的含量均在Fe浓度为6.0~12.0mmol·L~(-1)下达到最大值,且在3周时的含量显著高于其余处理时间;麦角新碱含量在第3、6周时均于Fe浓度为0mmol·L~(-1)下达到最大值,在第9周时则于Fe浓度为0.03mmol·L~(-1)条件下达到最大值。研究认为,高浓度短时间的Mn、Zn和Fe元素处理有利于刺激醉马草内生真菌共生体2种麦角碱的积累,可通过控制3种微量元素的浓度和共生体的生长时间来提高2种麦角碱的含量,为今后能萃取更高浓度的麦角酰胺和麦角新碱作为临床药剂或生物农药提供较精确的外界条件。     

Phytolacca acinosa Roxb. with Arthrobacter echigonensis MN1405 enhances heavy metal phytoremediation

The growth and metal-extraction efficiency of plants when exposed to toxic metals can be enhanced by inoculating with certain bacteria, but the mechanisms of this process remain unclear. We report results from glasshouse experiments on the effect of Arthrobacter echigonensis MN1405 in promoting Phytolacca acinosa Roxb. growth when exposed to 100 mg/L Mn solution. Mn removal efficiency in solution was significantly enhanced by bacterial inoculation; Mn was accumulated in the root of P. acinosa Roxb. plant. The bacteria oxidized the Mn on root surface, which formed a Mn plaque to serve as a barrier or a containment to prevent metal toxicity. In this process, pH condition was an important factor on the effects of microbial-assisted heavy metal phytoremediation. Our finding suggests that A. echigonensis MN1405 assisted P. acinosa to achieve high remediation efficiency of Mn removal and accumulation in Mn contamination area.     

Systematic Investigation of Porphyrin‐Thiophene Conjugates for Ternary Bulk Heterojunction Solar Cells

A family of porphyrins and benzoporphyrins bearing phenyl, thiophenyl, or bithiophenyl groups at their meso‐positions are synthesized and systematically investigated for their potential use in bulk heterojunction solar cells (BHJ‐SCs). Comparative studies of these compounds show that the introduction of the thiophenyl and bithiophenyl groups, and the extension of the porphyrin π‐conjugated system significantly affect both photophysical and electrochemical properties. Binary conventional and ternary converted BHJ‐SCs based on these compounds are fabricated and studied. Results show that remarkable enhancement of the device efficiency is achieved by using the thiophene‐containing benzoporphyrin derivatives as additives for a poly(3‐hexylthiophene) (P3HT):phenyl‐C61‐butyric acid methyl ester blend in the inverted BHJ‐SCs. The optimum BHJ‐SC exhibits a maximum energy conversion efficiency of 4.3%, corresponding to 19% enhancement of the conversion efficiency as compared with the benchmark BHJ‐SCs.     

The Regional Distribution of Monoamine Oxidase Activities Towards Different Substrates: Effects in Rat Brain of Chronic Administration of Manganese Chloride and of Ageing

Abstract: The effects of chronic manganese chloride administration (1 mg MnCl₂ 4H₂O/ml of drinking water) and ageing on the regional distribution of monoamine oxidase (MAO, EC 1.4.3.4) were studied in 2-month- and 24–28-month-old rats. In both the control and Mn-treated rats, the serotonin oxidation (type A) rates decreased in hypothalamus, pons and medulla, striatum, midbrain and cerebral cortex, but not in cerebellum, in ageing. On the other hand the benzylamine oxidation (type B) rates in hypothalamus, striatum and cerebral cortex increased in ageing. In all regions except the cerebellum, there was a uniform decrease in the A/B ratio. This decrease was verified by differential inhibition studies using clorgyline and l -deprenyl, specific type A and type B inhibitors respectively. The dopamine-oxidising rates decreased in all regions, except the cerebral cortex and the cerebellum, in ageing control rats. This age-related decrease was not seen in the striatum and midbrain of manganese-treated rats. In these rats the other effect was an age-related increase in the rate of oxidation of all the amines in the cerebellum, not observed in control rats. These selective effects of manganese are only seen when comparing age-related changes in both groups of animals, since comparison of manganese-treated rats with age-matched controls showed a significant difference only in the rate of serotonin oxidation in the cerebellum of 2-month-old rats. The relationship of these observations to the effects of ageing and manganese encephalopathy on specific amine systems is discussed.     

The role of dietary copper,manganese, selenium,and vitamin E in lipid peroxidation in tissues of the rat

The role of dietary Cu and Mn in maintaining tissue integrity, through the effects of these metals on activity of the superoxide dismutase (SOD) enzyme, and their interactions in peroxidative pathways involving Se and vitamin E was investigated. Weanling rats were fed diets deficient in Mn, Cu, Se, and/or vitamin E for 35 days, in a factorial experimental design. Dietary effects on peroxidation, measured in mitochondrial fractions prepared from liver and heart tissue, were compared with changes in the activities of glutathione peroxidase and the Cu and MnSOD enzymes. Decreased heart MnSOD and CuSOD activities, resulting from dietary Mn and Cu deficiencies, were both associated with increased peroxidation. Adequate Se (and glutathione peroxidase activity) prevented the peroxidation associated with either of these deficiencies, but was ineffective with a combined Cu−Mn deficiency. These effects of Se were only observed in tissue lacking glutathione transferase activity. Effects of Cu, Mn, and Se on peroxidation appeared to be present at both levels of vitamin E, although in both tissues, vitamin E deficiency greatly increased the overall peroxidation. Comparison of these in vitro peroxidation results with the deficiency associated lesions observed in vivo indicates that changes in SOD activities and peroxidation pathways may be the dominant cause of these lesions in only some cases. In others, the roles of Cu and Mn in different metabolic pathways appear to be of greater importance.