Phosphate Glass Electrode with Good Selectivity for Alkaline-Earth Cations

A phosphate glass has been found to have a significant electrode specificity toward alkaline-earth ions. The order of selectivity is 2H(+) > Ba(++) > Sr(++) > Ca(++) > 2K(+) > 2Na(+) > Mg(++). Exchange properties are discussed in relation to possible structure. Its use to determine activity of Ca(++) in natural systems containing Mg(++) is sug gested.     

Uncoupling of a nerve cell membrane junction by calcium-ion removal

Calcium ion participates in maintaining electrical connections between the nerve cells of Retzius (Hirudo medicinalis). The conductance across the junction between these cells decreases with decreasing concentration of free, extracellular Ca(++) At a certain level of Ca(++) withdrawal from the cell system, junctional conductance reaches a critical low point at which the cells become functionally disconnected: the nerve impulses which are normally discharged in synchrony by the cells become asynchronous. These effects of Ca(++) on junctional connection are irreversible, in contrast to those on nonjunctional surface membrane permeability.     

Tetrodotoxin and manganese ions: effects on electrical activity and tension in taenia coli of guinea pig

Tetrodotoxin, at concentrations up to 5 x 10(-6) gram per milliliter, has no effect on the spontaneous discharge in the smooth muscle of taenia coli. However, the spontaneous discharge is abolished by Mn(++) at a concentration of 0.5 millimole per liter. The contraction induced by immersing the muscle in isotonic KCl solution is also suppressed in the presence of Mn(++). Because Mn(++) is a specific suppressor of the spike induced by Ca(++) and tetrodotoxin is an inhibitor of the spike induced by Na(+), we suggest that Ca(++) is a charge carrier in the production of spike potential in the smooth muscle and that the entry of intervening Ca(++) through the membrane acts as a trigger for the contraction of smooth muscle.     

营养平衡与代谢对锦橙裂果的影响

严重裂果的锦橙叶片和裂果果皮的Ｋ，Ｃａ和Ｍｇ元素处于不适宜的平衡状态。低Ｋ水平，出现在低Ｋ／Ｃａ＋Ｍｇ，Ｋ／Ｃａ或低Ｋ／Ｍｇ比值下，叶片Ｋ／Ｃａ，Ｋ／Ｍｇ，Ｋ／Ｃａ＋Ｍｇ比值和果皮Ｋ／Ｍｇ比值与裂果率呈极显著或显著负相关和高度线性回归关系。叶片和果皮的Ｃａ／有效Ｂ比值与裂果率呈显著或极显著正相关及高度线性回归关系。Ｃａ／有效Ｂ比值比单纯的Ｃａ，Ｂ营养强度指标能更好地反映与裂果发生的关系。在锦橙裂果     

Uncoupling of an epithelial cell membrane junction by calcium-ion removal

Calcium takes part in maintaining ion communication between salivary gland cells (Chironomus thummi). Its withdrawal from the cell systems results in virtual disconnection of ion communication, at Ca(++) concentrations which do not noticeably affect cell adhesion. The junctional membrane surfaces. which are normally quite freely permeable to ions, become as impermeable as the nonjunctional membrane surfaces; each cell seals itself off irreversibly as a unit. In maintaining ion communication Mg(++) substitutes for Ca(++)     

叶面喷施硫酸钾镁肥对不同部位烟叶镁、钾、钙吸收的影响

[目的]在云南省曲靖市植烟土壤交换性钙镁比超过20的缺镁烟区,通过土壤镁肥施用和叶面喷施进行钙镁比调控,了解其对烤烟钾、钙、镁吸收的影响,为曲靖市缺镁烟区烤烟的平衡施肥技术提供理论依据和生产指导。[方法]通过田间小区试验,采用完全随机区组设计,以不施镁肥作为对照,分别设3个叶面喷施硫酸钾镁肥处理和2个根层施镁+叶面喷施处理。采集根、茎、上部叶、中部叶和下部叶5个部位进行烘干称重,并且粉碎制样,测定钾、钙、镁含量;每个小区从初烤烟叶中选取上部(B2F)、中部(C3F)下部(X2F)样品,分析烟叶全钾、钙、镁含量。[结果]从不同部位来看,叶面喷施及土壤施用和叶面喷施配合调控钙镁比提高了中、下部烟叶对镁、钾的吸收以及下部烟叶对钙的吸收,但降低了上部烟叶对镁、钾、钙的吸收以及中部烟叶对钙的吸收。烟叶不同部位镁、钾、钙的累积分配量比较表现为中部叶下部叶上部叶;从不同部位来看,中、上部烟叶钙镁比、钾镁比降低,下部烟叶钙镁比增加,而下部烟叶钾镁比处理之间没有差异。[结论]叶面喷施及土壤施用和叶面喷施配合调控对烟叶钙镁比、钾镁比的影响,主要是通过影响镁的吸收。     

Interactive effects of organic fertilizer, CaSO4 and amino acid Ca on Fuji apple in Burozem soil in China

A two-year trial was conducted to test the interactive effects of special-for-apple organic fertilizer, CaSO₄, and amino acid Ca on Fuji/Balenghaitang (Malus robusta Rehd.) rootstock in Burozem soil in China. Total Ca, exchangeable Ca, and fruit Ca were significantly improved by the soil application of CaSO₄ with the highest exchangeable Ca and fruit Ca observed in Fuji apple trees treated at the rate of 3.5 kg CaSO₄ per tree. 3.5 kg CaSO₄ was divided into two applications, with first application in the first month after full bloom, and the second in the second month after full bloom in summer, progressively to improve fruit Ca concentration. Dividing CaSO₄ into two applications in combination with organic fertilizer or amino acid Ca spray, proved to be more effective on improving the fruit Ca concentration, with the highest level of 179.17 mg/kg FW in Fuji apple trees treated with 2 kg CaSO₄ applied and amino acid Ca sprayed in the first month after full bloom, 1.5 kg CaSO₄ applied in summer, organic fertilizer applied in winter. Organic fertilizer applied in winter alone remarkably improved the fruit Ca concentration, as well as storage Ca in roots and stems, and the best effect was observed in Fuji apple trees which were supplemented organic fertilizer (10 kg) in winter and CaSO₄ (1 kg) in the first month after full bloom per tree. The effect on Ca increment became less pronounced when the amount of organic fertilizer reached 15 kg or CaSO₄ was more than 3.5 kg per tree. There was a positive correlation between the Ca/Mg ratio in soil and fruit, exchangeable Ca, and fruit Ca concentration, while a negative correlation was observed between the N/Ca ratio in fruit, available P, available K in soil, and fruit Ca concentration. Both N/Ca ratio and Ca/Mg ratio in fruit were affected by different fertilization regime, and bitter pit incidence at the end of storage kept acceptable only if N/Ca < 17 and Ca/Mg ≥ 7 at harvest. The commercial fertilization regime turned out to be organic fertilizer in combination with CaSO₄ applied in soil in winter, amino acid Ca sprayed in the first month after full bloom, and CaSO₄ applied in soil in summer. __________ Translated from Journal of Fruit Science, 2007, 24(1): 6–10 [译自: 果树学报]     

卵黄、牛奶及EDTA对冷冻过程中猪精子内Zn~(++)和Ca~(++)含量的影响

冷冻过程中,卵黄能有效地抑制精子内Zn~(++)含量的升高,而牛奶则无此作用。由于卵黄和牛奶中都含有大量的Ca~(++),因此当用作保护剂时,会使冻后精子内Ca~(++)的含量大大升高,但卵黄的影响较小。如果在卵黄中加入EDTA,则能明显阻止精子内Ca~(++)含量的升高。而且,解冻后精子的存活时间也延长。试验结果表明:(1)卵黄对精子的保护作用优于牛奶;(2)卵黄和牛奶中的Ca~(++)会影响解冻后精子的存活,但添加EDTA后可得到明显改善。     

Calcium carbonate concretions formed by the decomposition of organic matter

Bacterial decomposition of butterfish and smelts in small sealed jars containing seawater and other solutions, for periods ranging from 65 to 205 days, results in a large increase in concentrations of dissolved bicarbonate, carbonate, and ammonia (plus volatile amines). Accompanying this is a rise in pH and the precipitation of Ca(++) ion from solution. The Ca(++) is not precipitated as CaCO(3) but instead as a mixture of calcium fatty acid salts or soaps with from 14 to 18 carbon atoms. This can be explained by the thermodynamic instability of CaCO(3) relative to Ca soaps in the presence of excess free fatty acid. It is suggested that some ancient CaCO(3) concretions, especially those enclosing fossils of soft-bodied organisms, may have formed rapidly after death in the form of natural Ca soap (adipocere) which was later converted to CaCO(3).     

Participation of an intermediate of oxidative phosphorylation in ion accumulation by mitochondria

Heart mitochondria accumulate massive amounts of Mg(++) and phosphate or Ca(++) and phosphate when incubated under appropriate conditions. Studies with inhibitors of respiration, oligomycin, and uncouplers of oxidative phosphorylation indicate that the energy necessary for these reactions may be provided either in the form of ATP in the absence of electron transport, or in the form of a high-energy intermediate of oxidative phosphorylation, which operates even though ATP is not produced.     

落叶前根外追肥对苹果休眠期营养状况的影响

本文于落叶前向苹果树根外追施矿质肥料,落叶后采样测定了氨基酸、可溶性糖和Ｐ、Ｋ、Ｂ、Ｃａ的含量。结果表明,喷含Ｃａ２＋、Ｋ＋、ＳＯ２－４、Ｈ２ＰＯ－４、ＮＯ－３及尿素等肥料均使粗根中氨基酸含量下降,除ＳＯ２－４外其它肥料能促进氨基酸由长枝下运至根系;ＫＮＯ３、Ｂ使根枝中可溶性糖含量增加,而Ｋ２ＳＯ４、ＣａＳＯ４、Ｃａ（ＮＯ３）２、ＫＨ２ＰＯ４使其含量下降;根外追肥促进Ｐ在粗根和枝条中贮存,其效果依次是：ＫＨ２ＰＯ４＞Ｋ２ＳＯ４＞尿素＞ＫＮＯ３,ＫＨ２ＰＯ４、尿素促进Ｃａ在短枝中的贮藏;Ｂ在喷肥后略有减少;根外追肥对Ｋ＋在粗根贮藏影响不显著。     

钙对盐胁迫水稻生长和营养元素吸收的影响

为揭示Ca对盐胁迫水稻的生长和营养元素吸收的影响,以日本晴水稻为材料,采用水培方式,设置不同浓度Ca和Na处理以及正常营养液处理开展对比试验,结果表明:盐胁迫水稻地上部的生长损害较为严重,外界供应5 mmol/L Ca能够修复25 mmol/L Na造成的生长损害。Ca对盐胁迫水稻的修复作用不是通过提高根系活力,而是通过降低水稻Na的吸收同时恢复根系K的吸收从而扩大根冠比实现的。水稻根系Ca含量对外界Ca和Na浓度的变化反应顿感,但地上部变化与Ca浓度成正相关。Na和Ca对Mg吸收的竞争作用主要表现在地上部的差异,根系几乎不受影响,但高Na能显著抑制水稻体内N的累积。     

Structural insight into the ion-exchange mechanism of the sodium/calcium exchanger

Sodium/calcium (Na(+)/Ca(2+)) exchangers (NCX) are membrane transporters that play an essential role in maintaining the homeostasis of cytosolic Ca(2+) for cell signaling. We demonstrated the Na(+)/Ca(2+)-exchange function of an NCX from Methanococcus jannaschii (NCX_Mj) and report its 1.9 angstrom crystal structure in an outward-facing conformation. Containing 10 transmembrane helices, the two halves of NCX_Mj share a similar structure with opposite orientation. Four ion-binding sites cluster at the center of the protein: one specific for Ca(2+) and three that likely bind Na(+). Two passageways allow for Na(+) and Ca(2+) access to the central ion-binding sites from the extracellular side. Based on the symmetry of NCX_Mj and its ability to catalyze bidirectional ion-exchange reactions, we propose a structure model for the inward-facing NCX_Mj.     

Microdetermination of Calcium by Aequorin Luminescence

A bioluminescent protein, aequorin, isolated from the jellyfish Aequorea in dilute disodium ethylenediaminetetraacetate solution, emits light on addition specifically of Ca(++) or Sr(++), thus providing the basis for a simple, quantitative micromethod for the determination of these cations, especially in biological fluids.     

供Mg水平对烤烟累积N、K、Ca、Mg的影响

盆栽试验表明 :(1 )供 Mg促进烟株对 NO- 3-N的吸收和积累 ;(2 )供 Mg极显著提高烟叶中 Mg的含量 ,但也显著降低 K和 Ca的含量 ;(3 ) Mg与 K、Ca之间存在着拮抗作用 ;(4 )供 Mg提高烟叶的 K/(Ca+Mg)值 ,改善卷烟燃烧品质 .缺Mg,K/(Ca+Mg)比值较低 ,品质不良     

套袋对‘红富士’苹果品质和Ca、Mg、K营养的影响

分别于盛花后25、35、45、55d对‘红富士’苹果进行套袋(果袋为内层红色袋、外层外灰内黑双层纸袋)处理,结果表明,早期套袋有提高果实单果重的趋势,降低果实可溶性固形物含量,对硬度和可滴定酸影响不大。果实成熟时,不同时期套袋对果肉Ca、K含量没有显著差异,但早期套袋增加果肉Mg含量,降低Ca/Mg比值。同时,在盛花后35d进行3种果袋(内层白、外层外灰内灰双层纸袋;内层黑、外层外灰内黑双层纸袋;内层红、外袋外灰内黑双层纸袋)处理表明,与对照(不套袋)相比,套袋使果实单果重增加,可溶性固形物含量降低,Ca含量、Ca/K影响不显著;而内袋红、外袋内黑外灰双层纸袋处理的果实Mg含量显著高于对照,内袋黑、外袋内黑外灰双层纸袋的果实K含量显著低于对照,并且上述两种果袋处理的果实Ca/Mg比值显著低于对照,其余果袋对品质和Ca,Mg,K均无明显的影响。     

硅钙镁钾肥对桑树生长、桑叶产量及品质的影响

通过田间小区试验,研究不同用量硅钙镁钾肥对桑树生长发育及桑叶产量、品质的影响。结果表明：相对于农民习惯施肥,配施硅钙镁钾肥能够显著增加春、夏、秋三季桑树的新稍数和平均枝长,同时明显提高了桑叶净光合速率（Pn）和SPAD值,硅钙镁钾肥处理的桑树单株叶片数和百叶重均明显提高,最终提高了三季的桑叶产量,全年桑叶产量较对照提高4．47％～14．61％,差异性显著。此外,配施硅钙镁钾肥能够提高桑叶品质,桑叶中蛋白质、氨基酸、油脂及还原糖含量显著高于对照处理。综合研究结果,建议桑园生产硅钙镁钾肥施用量以75k-667m2为宜。     

云南野生大树杨梅果实营养成分分析

 对云南野生大树杨梅果实营养成分分析,结果表明,果实中除含有糖、有机酸外,还含有丰富的维生素、矿物质及氨基酸等营养成分。果实中矿物质和微量元素的测定结果表明,钾、钙等成分含量明显高于其它水果,特别是钾的含量,高达1020mg／kg,是一般水果含量的10~80倍。杨梅果实中含有17种氨基酸,其中含人体必需氨基酸7种。     

不同基质对中苗期红掌生长及体内氮、磷、钾、钙、镁养分吸收利用的影响

通过不同体积比的粗砂、椰衣、椰糠、花生壳、谷壳的组合对中苗期红掌品种＂热情＂的处理,研究了不同基质配比对中苗期红掌植株的生长以及N、P、K、Ca、Mg养分吸收利用的影响,结果表明：配方为V椰糠∶V谷壳∶V花生壳=2∶1∶1的栽培基质其各项理化性状更优,且最有利于中苗期红掌的生长及干物质的积累;中苗期红掌地上部及地下部N、P、K、Ca、Mg的利用率之间无显著规律性,但上述元素的积累量也在配方为V椰糠∶V谷壳∶V花生壳=2∶1∶1的栽培基质上最高。     

牧草施肥试验(1988～1989)

对建植初期的混播人工草地施用尿素、钙镁磷肥、氯化钾和石灰,对产草量的影响主次顺序为磷>氮>钙>钾,对蛋白质的影响主次顺序为氮>钾>磷>钙(石灰),高酸度土壤施用石灰对提高牧草越夏率具有明显作用。