Studies of slowly available potassium in soils of New Zealand

Summary The concentration of K in the soil solution at zero change of non-exchangeable K (Co) was determined at 20°C and 50°C for six topsoils of widely different clay mineralogy. This was done with and without prior removal of the K that was exchangeable to dilute salt solutions in a two to three hour leach. Except for one case Co was greater for leached than for not leached samples, particularly at the higher temperature. This is attributed to rapid edge-weathering during leaching caused by interlayer penetration at the clay edges by calcium, sodium or hydronium ions. It is assumed that K newly exposed in this manner is not immediately exchangeable but that it exerts an influence on the equilibrium concentration of K in solution.Among soils Co was not related to the K available to ryegrass nor to the non-exchangeable K fraction of the uptake by ryegrass. However, much reduced values of Co were obtained after depletion by ryegrass in the new two soils examined.     

Determination of K forms in K-fertilized soils by electro-ultrafiltration

We confirmed the suitability of electro-ultrafiltration (EUF) for (a) determination of the distribution of potassium fertilizer among the various forms of potassium in soils with a predominance of micaceous minerals in their clay fraction, and (b) investigated the effects of the degree of openness of the dominant micaceous mineral and of incubation time on the kinetics of the EUF extraction of K from these soils.Samples of illitic, mixed-layer and vermiculitic soils from Galicia (N.W. Spain) were incubated at field capacity for 450 days with 0 (blank), 5,15 or 25 mg K (as KCl) per 100 g dry soil. After 1, 30, 150 and 450 days, subsamples were removed and repeatedly extracted using electro-ultrafiltration at low (20° C/200 V) and then high (80° C/400 V) temperature/voltage (6 and 10 five-minute extractions, respectively). Five different pools of K were identified: solution K (K_s), surface and internal K (collectively, K_p), slowly exchangeable K (K_e) and non-exchangeable K (K_i). The effects of increasing the incubation time depended on the dominant clay mineralogy: after 450 days, the K added to illitic soils was mostly solution K, whereas that added to vermiculitic soils was mostly internal K.For both low and high temperature/voltage EUF experiments, the extraction-time data were best fitted by the Elovich equation (extracted K=a+b ln t). The kinetic coefficient b depended on the incubation time and dominant clay mineral, and for given soil and incubation time increased linearly with the dose of added K.Abbreviations EUF Electroultrafiltration - K_s Solution potassium - K_p Easily exchangeable (surface + internal) potassium - K_e Slowly exchangeable potassium - K_i Non-exchangeable potassium     

The relationship between EUF-K and soil-K fractions of different K selectivity

Summary The fraction of K released during EUF 30-35 min, 80°C, 400 V (EUF₃) and various other soil-K parameters were compared for 24 soils that range widely in clay mineral composition, clay content and percentage K saturation. When EUF₃ was compared with fractions of soil-K containing increasing amounts of non-exchangeable K (=selectively adsorbed K), the R² values decreased with increasing quantities of non-exchangeable K. This indicates that EUF₃ is a function of the exchangeable pool of K, although some initially non-exchangeable K is also involved.     

EUF-K as measure of K availability index for Tamil Nadu soils (India)

Summary Representative soils of Tamil Nadu could be grouped into three categories based on the cumulative EUF desorption K curves which were exponential and displayed marked differences in the magnitude of K release by the soils employed. The cumulative K desorption values and the cumulative K uptake values of rice were found to be closely correlated. When compared with any other method, the cumulative EUF desorption K was found to be a better measure of K availability index.     

Atrial natriuretic factor: atrial conversion of high to low molecular weight forms

The atrial natriuretic factor elutes by gel filtration in high and low molecular weight fractions. Extraction and elution of rat atria in 1.0 M acetic acid yielded a predominance of the high molecular weight form(s); whereas when these procedures were carried out in 0.1 M acetic acid, there was a predominance of the low molecular weight forms. When partially purified high molecular weight natriuretic activity was eluted in 0.1 M acetic acid, the high molecular weight form(s) remained intact. When partially purified high molecular weight natriuretic activity was mixed with crude atrial extract in 0.1 M acetic acid, there was an apparent conversion to the low molecular weight forms. Extraction of rat atria in boiling 0.1 M acetic acid blocked this conversion. It is concluded that rat atria contain a heat labile factor that converts high molecular weight natriuretic activity to the low molecular weight forms.     

农田生态系统中钾循环研究进展

论述了农田生态系统中K的收入和支出,以及K的循环再利用等方面的研究进展,并针对当前K循环存在的问题提出了调控方法.从全国来看,我国施用K的数量比作物收获时从土壤中带走的K的数量少得多,K一直处于负平衡状况.我国土壤K肥力不断下降、钾肥有效地区不断扩大,虽然钾肥用量在逐年增长,但补充的K尚不能维持K的收支平衡.为了维持与提高土壤K肥力,使作物高产稳产,在今后农业生产中应充分注意土壤K的平衡,优化农田生态模式,注重水肥调控,坚持有机肥与无机肥配施的原则,促进K养分循环,保持农田K平衡,提高土壤K肥力.     

Potassium supplying capacity of northeastern Portuguese soils

In Portugal, the response to K application is often inconsistent with the Egner-Riehm values for available K. This is partly related to high K reserves of some soils. Twenty surface soils representative of different parent materials from NE Portugal were studied to determine their K supplying capacity. Continuous cropping with perennial ryegrass permitted the assessment of the relative ability of soils to release non-exchangeable K. Soils were classified in the range of available K from medium to very high. However, their ability to supply K in the short and long term are very different. In some soils K status measured by plant growth does not fall appreciably, whilst others are rapidly exhausted, and 30% of them are very deficient in K. The supplying capacity varied both with the nature of the parent material and the degree of weathering. The soils deficient in K are those derived from basic rocks and those with more weathered clay minerals. This is the case of the soils with the largest content of organic matter where the dominant clay minerals were kaolinite and vermiculite. Soils that have the highest capacity for supplying K are highly micaceous, like those developed from mica schists, phyllites or river alluvium. In fact the amount of K released from non-exchangeable form is well correlated with the amount of illite in the clay fraction. Soil types and K buffer power coupled with available K must be taken into account when planning any application of K.     

脱氧雪腐镰刀菌烯醇对K~＋刺激的小麦根质膜ATP酶活性、K~＋吸收、外渗及再分配的影响

１０－８ｍｏｌ／Ｌ的ＤＯＮ毒素加入小麦根质膜制剂中可促进Ｋ＋刺激的ＡＴＰ酶活力,１０－６ｍｏｌ／Ｌ开始呈抑制效应,抑制程度随ＤＯＮ浓度加大而提高。根尖（５ｃｍ）离体根段于０．５ｍｍｏｌ／Ｌ的ＫＣｌ中,１０－８ｍｏｌ／Ｌ的ＤＯＮ能促进根段Ｋ＋吸收,１０－６ｍｏｌ／Ｌ以上浓度则Ｋ＋吸收呈抑制,１０－２ｍｏｌ／Ｌ浓度下根段的净吸收为负值,表明组织中Ｋ＋大量外渗。根段置蒸馏水中６ｈ,４ｍｍｏｌ／Ｌ的ＤＯＮ即导致振段Ｋ＋渗漏。用ＤＯＮ处理整株小麦根,浓度在０．２５ｍｍｏｌ／Ｌ以上可促进Ｋ＋从植株其它部位向根运输,而浓度在８ｍｍｏｌ／Ｌ时即抑制Ｋ＋向根富集,且根内Ｋ＋明显渗漏。     

A hetero-dimer model for concerted action of vitamin K carboxylase and vitamin K reductase in vitamin K cycle

Vitamin K carboxylase (VKC) is believed to convert vitamin K, in the vitamin K cycle, to an alkoxide-epoxide form which then reacts with CO₂ and glutamate to generate γ-carboxyglutamic acid (Gla). Subsequently, vitamin K epoxide reductase (VKOR) is thought to convert the alkoxide-epoxide to a hydroquinone form. By recycling vitamin K, the two integral-membrane proteins, VKC and VKOR, maintain vitamin K levels and sustain the blood coagulation cascade. Unfortunately, NMR or X-ray crystal structures of the two proteins have not been characterized. Thus, our understanding of the vitamin K cycle is only partial at the molecular level. In this study, based on prior biochemical experiments on VKC and VKOR, we propose a hetero-dimeric form of VKC and VKOR that may explain the efficient oxidation and reduction of vitamin K during the vitamin K cycle.     

Influence of FeEDDHA and soil temperature on the growth of two soybean varieties

Bulk samples of 30 surface soils characterized in the National Cooperative Soil Survey of Louisiana were collected at the original sites and planted with sorghum-sudangrass in the greenhouse. The native K was exhausted by a total of four croppings. The available soil K was extracted with 1N NH₄OAc 7.0 and 0.1N HCl while the difficultly available-K was extracted by 0.3N NaTPB (sodium tetraphenylboron). In addition, the mica content was estimated by differential dissolution. All soils except Dundee produced the greatest dry matter yield in the first crop with steadily decreasing production in the succeeding crops. The same pattern was shown in the K uptake. It appears that the first crop removed a large portion of the exchangeable K. There was a high degree of relationship between plant uptake of K and exchangeable K in the soils (r²=0.89^**). Uptake by the subsequent crops was generally controlled by the K in the micaceous minerals (r²=0.89^**). Since there was a high coefficient of determination between mica-K and difficulty available-K (r²=0.91^**) one also finds that uptake of K by crops 2, 3 and 4 was also well correlated to difficultly available K (R²=0.94^**). The uptake of K that was not originally in the exchangeable form was also highly related to difficultly available-K (R²=0.51^**). Contribution from the Department of Agronomy, Louisiana Agricultural Experiment Station, Louisiana State University Agricultural Center, Baton Rouge. Part of the M.S. theses of the senior authors. Former Graduate Students and Prof. of Agronomy, respectively.     

水溶性红曲中MonacolinK的稳定性

对红曲中Monacolin K（MK）在水溶液中的稳定性进行研究,考察不同加热温度、时间、pH、盐、维生素C（VC）、氨基酸、蔗糖质量浓度、光照和存放时间对其稳定性的影响。结果表明：100℃保温30min,水溶液中Monacolin K的浓度比20℃保温相同时间仅下降了4．6％。热处理、长时间光照对水溶液中Monacolin K有轻微的破坏作用：pH〈5．0,盐、VC、氨基酸的添加可降低水溶液Monacolin K溶解度。pH〈4．0可使酸型Monacolin K转化为内酯型。在Monacolin K水溶液中添加30g/L蔗糖可使水溶液中Monacolin K饱和质量浓度增至632．9mg／L。     

一株Monacolin K高产菌株生理特性

根据丝状真菌的常用鉴定方法,对实验室保存的一株Monacolin K高产菌株进行形态和生理特性实验。结果表明该菌株属于真菌门(Eumycophyta)、子囊菌纲(Asomycetes)、真子囊菌亚纲(Eurotiaceae)、曲霉目(Eurrotiales)、曲霉科(Eurotiaceae)、红曲霉属(Monascus)。     

红曲霉液态发酵生产Monacolin K培养基的优化

利用正交试验设计对红曲霉TQ-57发酵生产Monacolin K的摇瓶发酵培养基进行了初步研究。结果表明:Monacolin K的最适发酵碳源为甘油,最佳添加质量分数为14%,最适氮源为蛋白胨,最佳氮源质量分数为3%,培养基初始pH为6.5,培养周期为8 d,在此条件下Monacolin K产量可达27.75 mg/L。     

人参总皂苷对K562细胞STAT3表达的影响

目的:研究人参总皂苷(TSPG)体外作用k562细胞后STAT3蛋白在细胞中的表达、分布情况和STAT3通路在K562细胞分化中的作用和相关机制.方法:TSPG(200μg/ml)体外作用K562细胞不同时间,采用免疫细胞化学法、ELISA法、Western blotting法、激光共聚焦法检测K562细胞中STAT3表达、分布情况.结果:6h胞浆内STAT3蛋白吸光度0.306±0.038,12h降为0.170±0.037,之后逐渐回升,胞核内变化趋势则相反;免疫细胞化学法显示TSPG作用细胞12h,胞浆内呈浅棕色,胞核内呈深棕色;Westernblotting法检测列STAT3与β-actin吸光度比值胞浆内12h最低,胞核内最高;共聚焦观察TSPG作用细胞12h,胞浆内绿色荧光标记减少,核内绿色荧光标记增多,与红色细胞核颜色叠加呈现橙色.结论:TSPG作用K562过程中,能诱导STAT3由浆向核内转移,提示TSPG可能在JAK-STAT信号转导通路中,对促进K562细胞向成熟方向分化发挥重要作用.     

Assessment of Soluble and Biomass K in Culture Medium Is a Reliable Tool for Estimation of K Releasing Efficiency of Bacteria

Abstract

Assessing the amount of released K from minerals in bacterial liquid culture is the main process for screening and isolation of efficient potassium releasing bacteria (KRB). This study was aimed to determine the amount of released K in solution phase or supernatant (SK) as well as microbial biomass K (MBK). Therefore, 20 different bacterial isolates belonging to the 10 bacterial genera (Beijerinckia, Klebsiella, Azotobacter, Pseudomonas, Agrobacterium, Rhizobium, Sphingomonas, Citrobacter, Microbacterium, and Achromobacter) were individually used to inoculate Aleksandrov medium in presence of biotite or muscovite. Our results from in-vitro experiments revealed that the MBK (K in pellet) is more important than in SK. Although some genera such as Azotobacter and Citrobacter released more SK (16?mg/l from biotite and 12.77?mg/l from muscovite, respectively), the Klebsiella isolates with the highest MBK could release an average of 90?mg/l total K. This study indicated that the assimilated K in microbial cells is the main part of K dissolution from minerals. Due to the fast turnover of nutrients in bacterial biomass, it can be concluded that both SK and MBK could be available for plants. It seems that the finding of this research should be considered in the isolation of KRB.

Highlights

• This study reports, assessment of soluble and biomass K in the culture medium is a reliable tool for estimation of K releasing efficiency of bacteria

• Our results from in vitro experiments revealed that the assimilated K in microbial cells is the main part of K dissolved from minerals.

• Although some genera such as Azotobacter released more K in solution phase, the Klebsiella isolates with the highest biomass K could release more total K

     

Androdioecy in Kryptolebias killifish and the evolution of self‐fertilizing hermaphroditism

Kryptolebias marmoratus is an important experimental fish, and is considered to represent the only vertebrate species comprising self‐fertilizing hermaphroditic individuals. Subsequent to the discovery of this unusual mode of reproduction, approximately 50 years ago, K. marmoratus has been the focus of a series of studies. However, little is known about the evolution of this rare reproduction mode, and data on the biology of closely related species are still unavailable. The present study aimed to histologically analyse the gonads of three K. marmoratus congeners (i.e. Kryptolebias ocellatus, Kryptolebias caudomarginatus, and Kryptolebias brasiliensis) to check the distribution of features related to hermaphroditism that are useful for forming hypotheses about the origin and evolution of the self‐fertilization mode of reproduction through the available phylogenies. The data obtained demonstrate that populations of K. caudomarginatus consist of males and hermaphrodites, which supports the hypothesis that hermaphroditism arose at the base of the clade containing K. caudomarginatus, K. marmoratus, and K. ocellatus as a first step towards a more advanced condition, uniquely shared by both K. marmoratus and K. ocellatus, in which males are rare or absent in natural populations, with the subsequent occurrence of self‐fertilization. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99 , 344–349.     

大豆过敏蛋白与品种改良

食物过敏是一个全世界关注的公共卫生问题。大豆蛋白在食品加工业的广泛应用,对大豆敏感人群带来了潜在的威胁。如何降低大豆过敏原含量提升大豆食品安全已成为日益关注的问题。大豆种子过敏蛋白包括种子贮存蛋白、结构蛋白和防御相关蛋白,其中7S 伴球蛋白的多肽片段Gly m Bd 28K, Gly m Bd 30K和Gly m Bd 60K是三种主要的过敏原。目前通过对过敏蛋白的理化性质、过敏原性和基因结构的认识,运用食品加工工艺、传统育种及基因工程技术等方法,在减少大豆和大豆产品的过敏原性方面已取得一定的进展。本文拟从大豆过敏原的分类、主要过敏原Gly m Bd 28K和Gly m Bd 30K的理化性质及基因结构、大豆过敏蛋白在遗传改良中的应用对大豆过敏蛋白进行综述。     

Simple empirical intensity and buffering capacity measurements to predict potassium uptake by white clover

Summary This experiment examined the feasibility of predicting K uptake in white clover by the use of simple and relatively rapid tests that would dispense with the need of knowing the quantity of plant available potassium. Potassium uptake was found to correlate highly (R=>0.9) in linear bivariate regressions using K concentration in the soil solution displaced by centrifuging and an empirical estimate of potassium retention. There was no advantage in determining activity ratios because in at least some of the soils used the ratio law did not apply. Exchangeable potassium alone correlated rather poorly with uptake except at very low soil potassium status. This was not because nonexchangeable potassium was an important source of this nutrient to white clover but because of the large differences in the retention of K amongst the soils used.     

盐胁迫下水稻苗期Na+和K+吸收与分配规律的初步研究

选择苗期耐盐性较强的水稻(Oryza sativa)品种(株系)'AB52'、'02402'和'02435'及敏感品种'日本晴',在网室周转箱内,设置5 000和8 000 mg·L-1NaCl两种盐处理,以清水为对照,研究盐胁迫下苗期水稻植株不同部位Na+和K+的吸收和分配与品种耐盐性的关系.结果表明,盐胁迫下,株高、绿叶干重和绿叶面积下降,绿叶中的水分含量降低,但茎鞘中的水分含量有所上升.5 000 mg·L-1NaCl胁迫处理10 d,耐盐品种所受的生长影响和叶片伤害程度低于敏感品种,但8 000 mg·L-1NaCl胁迫处理下品种间差异变小.盐胁迫下,水稻植株吸收Na+和置换出K+,但不同器官部位中Na+和K+的区域化分布特征明显,各部位的Na+含量由低到高依次为绿叶、根、茎鞘和枯叶.下部老叶能优先积累较多Na+而枯黄;绿叶吸收Na+相对较少,维持较低的Na+水平,同时保持较高且稳定的K+含量;植株茎鞘通过选择性吸收大量Na+和置换出一部分K+到叶片中,保持绿叶较稳定的K+含量和相对较低的Na+含量,维持较高的K+/Na+比,从而使植株少受盐害.敏感品种'日本晴'在盐胁迫下绿叶中的Na+含量相对较高,且5 000 mg·L-1NaCl胁迫下绿叶Na+含量已接近高值,与在8 000 mg·L-1NaCl胁迫下差异不大,而耐盐品种绿叶吸收较少的Na+.另一方面,耐盐品种茎鞘的含K+相对较高,在盐胁迫下能吸收容纳较多的Na+,而绿叶中K+/Na+比较高.可以认为,绿叶的K+/Na+比可作为一个衡量耐盐性的相对指标.     

结实期相对高温对稻米淀粉粘滞性谱及镁、钾含量的影响

选用武育粳3号(粳稻)和扬稻6号(籼稻)两个水稻品种,利用人工气候室在水稻灌浆结实期进行控温试验,设置全结实期相对高温、结实前期相对高温、结实后期相对高温、全结实期适温(对照,日均温23 ℃)对照4个处理,探讨结实期不同时段相对高温(日均温度-30 ℃)对稻米淀粉粘滞性谱和Mg、K等元素含量的影响.结果表明：结实期相对高温使武育粳3号和扬稻6号淀粉粘滞性谱特征值发生改变,其中糊化开始温度、冷胶粘度、回复值和消减值升高,最高粘度、热浆粘度和崩解值下降;结实期相对高温促进了米粉中Mg、K、N含量的提高,特别是K含量的大幅提高,使稻米中Mg/K和Mg/(N·AC·K)明显降低;而2个水稻品种的直链淀粉含量（AC）对相对高温的反应截然相反,武育粳3号的AC降低、扬稻6号的AC升高.全结实期相对高温对稻米淀粉粘滞性谱和Mg、K等元素含量的影响最大,结实前期其次,结实后期的影响较小,开花后20 d内是稻米淀粉粘滞性谱和Mg、K等元素含量受温度影响的关键时期.Mg/K和Mg/(N·AC·K)与淀粉粘滞性谱特征值显著相关,可以作为稻米食味品质评价的参考指标.