咖啡因对小麦幼苗生长,过氧化物酶同工 酶及根尖细胞有丝分裂的影响

３０ｐｐｍ以下浓度的咖啡因对小麦种子萌发,幼苗生长和胚根长度均有明显抑制作用。随着咖啡因浓度的增加,根尖细胞有丝分裂指数明显下降。低浓度时,过氧化物酶同工酶和苹果,酸脱氢酶没有变化,但高浓度时,使得这两种酶的活性几乎消失。     

咖啡因引起的蛙骨骼肌二酰基甘油累积和蛋白激酶C激活

以前的工作表明,高钾暴露可以导致蛙骨骼肌细胞二酰基甘油（ＤＡＧ）累积和蛋白激酶Ｃ（ＰＫＣ）激活。为探讨其作用机制,进一步研究了咖啡因对ＤＡＧ／ＰＫＣ信号转导途径的影响。结果表明。咖啡因能马浓度和时间依赖的方式卢蛙骨骼肌ＤＡＧ累积和ＰＫＣ激活。在乐自由钙升高达到相同峰值条件下,咖啡因引起的ＤＡＧ累积程度和时相明显不同于高钾。与此同时,咖啡因引起的ＰＫＣ激活也不同于高钾。咖啡因与高钾作用的差别进一步证     

番茄种子经激光和咖啡因处理后其当代生物效应的研究

咖啡因具有抑制一些酶的活性,可减弱或消除生物体自身对激光引起的生物效应的修复作用。试验证明咖啡因对番茄种子萌发有强烈的抑制作用,咖啡因和激光复合处理生物效应显著,可降低番茄种子的发芽,并促进番茄果实增大和生长前期速率加快。     

无花果蛋白酶在胍溶液中的分子折叠与活力变化研究

本文研究无花果蛋白酶（ＥＣ．３．４．４．１２）在不同浓度盐酸胍溶液中分子构象与活力变化关系。酶的内源荧光光谱,圆二色光谱与酶活力的变化表明：荧光光谱呈现二个明显的变化区域,低浓度胍（低于２ｍｏｌ／Ｌ）中,荧光发射峰基本不变,但荧光强度随胍浓度上升,随胍浓度断续增大（高于２ｍｏｌ／Ｌ）,酶的最大发射波长明显红移。当胍浓度低于１ｍｏｌ／Ｌ时,不仅不会使酶失活,反而使酶激活,当胍浓度高于１ｍｏｌ／Ｌ以上时,酶逐渐失活,使酶完全失活的胍浓度为６ｍｏｌ／Ｌ酶的圆二色光谱也随着胍浓度的改变而发生复杂的变化。将荧光变化,ＣＤ谱变化及活力改变结合起来,表明活力的激活与构象的明显变化似是同步发生的,从另一角度进一步说明酶活性部位柔性是充分表现酶活力所必需。     

金属离子对蜡蚧菌几丁质酶活力的影响

以蜡蚧菌(Ll)发酵液为材料,经分离纯化获得Ll几丁质酶(EC3.2.1.14)制剂.研究了金属离子对Ll几丁质酶活力的影响.结果表明,K+、Mg2+、Zn2+、Ca2+和Fe3+对几丁质酶活性有明显的促进作用,而Na+和Cu2+完全抑制几丁质酶的活性;Mn2+在低浓度时对酶有激活作用,随着浓度的升高表现出抑制作用;Fe2+和Ba2+的浓度低于0.5 mmol/L时对酶起抑制作用,而高于该浓度时则对酶有激活作用.     

过氧化物同工酶谱带染色条件的探讨

研究了过氧化氢浓度在过氧化物同工酶电泳分析中对染色时间及酶带颜色深浅的影响,和相同的酶液在测定酶活性时过氧化氢浓度对测定结果的影响,以及两者之间的相关性。研究表明,过氧化氢的浓度在染色中对染色的时间和酶带的颜色深浅有明显的影响,在一定的范围内随着底物过氧化氢浓度的升高,酶的活性降低,染色时间变长,酶带颜色变浅。这种相关性与供氢体无关,它可指导酶带染色中过氧化氢的用量。     

氨基酰化酶在LDS溶液中的失活与去折叠的比较研究

氨基酰化酶在阴离子去污剂十二烷基硫酸溶液中的失活与去折叠的研究结果表明,在低浓度的ＬＤＳ溶液中变性时,以荧光和紫外差吸收方法监测的酶分子构象尚未发生明显变化,而酶的活力已经大部分或几乎全部丧失。当ＬＤＳ浓度达１．６ｍｍｏｌ／Ｌ时,此时酶分子的构象变化才达到最大程度。在实验使用的ＬＤＳ的浓度范围内,用远紫外ＣＤ光谱监测的二级结构没有发生明显的变化。     

有机溶剂对蜡蚧菌几丁质酶的影响

以蜡蚧菌(Ll)发酵液为材料,经硫酸铵沉淀、离子交换和凝胶过滤,获得部分纯化的Ll几丁质酶(EC3. 2. 1. 14)制剂.研究了不同有机溶剂对Ll几丁质酶的影响.结果表明,丙三醇、甲醛和戊二醛对几丁质酶有抑制作用;丙酮对酶有激活作用;甲醇、乙醇、正丁醇和乙二醇在低浓度时对酶有激活作用,随着浓度的升高表现出抑制作用;二氧六环的浓度低于6 %时对酶的影响不明显,而高于6 %时对酶则有激活作用.     

北京棒状杆菌RNA聚合酶的提纯及其性质的研究

本文报道了北京棒状杆菌RNA聚合酶的分离和提纯方法。经DEAE纤维素层析提纯后的酶的比活比硫酸铵分段后提高53倍;低浓度利福平和放线菌素D对酶显示强烈的抑制作用;酶对外加DNA模板呈现明显的依赖性;酶的反应最适温度为37℃,最适pH为7.9,反应30分钟时酶活力达到最高值,当0．I 5M氯化钾存在时表现最高酶活性。此外,本文还报道了模板、二价金属离子浓度和抑制剂浓度对酶活力的影响。     

绿咖啡豆中低咖啡因绿原酸的提取分离研究

建立高效液相色谱—双波长同时检测咖啡豆提取物中绿原酸和咖啡因含量的方法。咖啡因和绿原酸在0.2～1.0 mg·mL-1范围内，峰面积与浓度呈现良好的线性关系。咖啡因：Y＝44077X＋227.78，R＝0.9997，RSD＝0.78%；绿原酸：Y＝34896X＋289.96，R＝0.9995, RSD＝0.93%。以绿原酸含量为指标，在单因素试验基础上建立正交试验，确定从绿咖啡豆中提取绿原酸的最佳条件为乙醇浓度20%，液料比6∶1，提取时间60 min，提取温度70 ℃。以咖啡因和绿原酸含量为指标，通过萃取试验，确定最佳脱咖啡因萃取剂为环己烷-三氯甲烷-丙酮混合溶剂，萃取工艺为1.5倍体积萃取剂萃取3次，产物中咖啡因含量由(3.52±0.08)%下降至(0.47±0.11)%。     

Some studies of the quality of irrigation water and the germination and growth of wheat at different concentrations of boron

Summary The irrigation water in use at the Punjab University New Campus is of good quality except the water of one tubewell which is relatively poor (high-salinity and low-sodium water) and has 0.45 ppm boron. Water with a boron content of upto 3.00 ppm did not affect the germination of the seeds of wheat (Triticum vulgare L. var. Mexi-Pak) and there was some stimulation of the growth of seedlings by an increase in the concentration of boron beyond 0.45 ppm. However, these seedlings, when transplanted to the soils supplied with waters containing different amounts of boron, showed a decrease in their growth at higher concentrations of boron with their ageing, and when these plants were about 100 days old and almost mature, their growth decreased significantly with an increase in the concentration of boron to 2.00 or 3.00 ppm in the water supplied to them. The growth of the plants of Mexi-Pak wheat is inversely related to the boron content of their tissues when it is more than 0.60 ppm. Mexi-Pak wheat is semi-tolerant to boron. re]19750605     

Degradation by Streptomyces viridosporus T7A of plant material grown under elevated CO2 conditions

The biodegradability of plant material derived from wheat grown under different concentrations of atmospheric CO2 was investigated using the lignocarbohydrate solubilising actinomycete, Streptomyces viridosporus. Growth of S. viridosporus and solubilisation of lignocarbohydrate were highest when wheat grown at ambient CO2 concentrations (350 ppm) was used as C-source. Growth of S. viridosporus and solubilisation were reduced when the plant material was derived from wheat grown at 645 ppm CO2. The results suggest that modifications in plant structure occur when wheat is grown under conditions of elevated atmospheric CO2 which make it more resistant to microbial digestion.     

Effect of a formulation of urea,thiourea and humate on nitrogen availability and yield of wheat

Summary Urea was mineralized completely in 15 days when applied at concentrations of 50 and 30 ppm nitrogen (N) in the soil. Humate showed no effect whereas thiourea with and without humate delayed nitrate formation by 30 days.In pot-culture experiment, humate at 1.0 ppm concentration increased the grain yield of wheat but not significantly. Urea (25 ppm N) and thiourea (5 ppm N) increased the grain yield significantly. This effect was stimulated by humate treatment. re]19760629     

Phosphorus-copper relationship in wheat

Summary A green-house experiment was conducted to study P–Cu relationship in wheat variety S-308 grown up to maturity. Treatments included five levels, each of P (0, 25, 50, 100 and 250 ppm) and Cu (0, 2.5, 5, 10 and 50 ppm) in all possible combinations. The yield, P and Cu concentration were more with the application of Cu upto 5 ppm with P, and P upto 50 ppm with Cu, over P alone and Cu alone, respectively. Application of 50 ppm Cu adversely affected yield and P concentration and 250 ppm P adversely affected yield and Cu concentration. Application of affected nutrient counteracted to a great extent the adverse effect of the other nutrient. The low levels of P and Cu were essential for better plant growth and efficient utilization of both the nutrients and antagonism was noted only when one of the nutrients was applied in high quantities.Contribution from the Department of Soils, Haryana Agric. Univ., Hissar-India.     

Tolerance of wheat and pea to boron in irrigation water

In a micro-plot experiment 1.5 ppm boron in the irrigation water was toxic for wheat. Its concentration in the soil solution increased to 1.53 ppm and in the plant tissue to 58 ppm. In pea plants 4 ppm B in the irrigation water was toxic with 2.00 ppm soil solution B and 213 ppm tissue B. Nitrogen in both species increased significantly and calcium decreased with the increase in B in irrigation water. The yield of wheat grain declined by 13, 20 and 32 per cent at the 4.0, 6.0 and 8.0 ppm B respectively. The yield of straw and grains of pea declined by 31, 56 and 41, 56 per cent at 6.0 and 8.0 ppm B levels respectively. Thus tolerance to B in irrigation water was between 3.0 and 4.0 ppm for wheat and 4.0 and 6.0 ppm for pea.     

Influence of instar and commodity on insecticidal effect of two diatomaceous earth formulations against larvae of Ephestia kuehniella (Lepidoptera: Pyralidae)

Laboratory experiments were carried out to evaluate the insecticidal effect of two diatomaceous earth (DE) formulations, SilicoSec and PyriSec, against larvae of Ephestia kuehniella Zeller (Lepidoptera: Pyralidae). Three instars were tested: first, third and fifth. The test was conducted in six commodities: barley Hordeum vulgare (L.) (Gramminae), rye Secale cereale L. (Gramminae), wheat Triticum sp. (Gramminae), wheat + 10% cracked wheat, wheat + 30% cracked wheat, and wheat flour. Quantities of these commodities were treated with the DEs at three dose rates: 250, 500, and 1000 ppm. Mortality of the exposed larvae on the DE-treated commodities was measured after 7 d of exposure. For both Des, mortality increased with dose, but this increase was lower when dose was increased from 500 to 1,000 ppm. The type of the commodity significantly affected DE effectiveness. Both DEs were equally effective on barley, rye, and wheat, whereas the presence of cracked wheat reduced larval mortality. In addition, significantly fewer larvae were dead on treated flour compared with the other five commodities. The increase of larval age significantly affected DE effectiveness. First instars were very susceptible to both DEs, and mortality with 1,000 ppm exceeded 86%. In contrast, fifth instar were the least susceptible to DEs, because mortality with 1000 ppm was < 22%.     

Caffeine Formulation for Avian Repellency

Abstract: Nonlethal management alternatives are needed to reduce avian depredation of agricultural crops. Caffeine has promise as an effective, economical, and environmentally safe avian repellent, yet formulation improvements are needed for field applications. We included sodium benzoate in subsequent formulations to enhance the solubility of caffeine. Red-winged blackbirds (Agelaius phoeniceus) discriminated between untreated rice and rice treated with 250 ppm or 10,000 ppm caffeine and sodium benzoate in captivity. We observed a positive concentration-response relationship among birds offered rice treated with 250 ppm, 1,000 ppm, 2,500 ppm, 5,000 ppm, 10,000 ppm, or 20,000 ppm caffeine and sodium benzoate. Relative to the pretreatment of the concentration-response test, repellency was >85% for rice treated with our 2,500- to 20,000-ppm treatments. We conducted seed germination experiments and associated residue analyses to evaluate the potential phytotoxicity of various caffeine formulations under controlled environmental conditions. The optimized formulation enhanced the solubility of tank mixtures and ameliorated the negative impacts of seed treatments to germination. Our caffeine formulation provides an applicable, nonlethal alternative for managing blackbird impacts to agricultural production.     

Effect of cleaning, milling, and baking on deoxynivalenol in wheat

Samples of wheat naturally infected by Fusarium graminearum Schwabe were obtained from mills in Oklahoma, Missouri, Kansas, and Minnesota and fields in Nebraska and Kansas in 1982; they were analyzed for deoxynivalenol (DON). The wheat was milled, and DON was found throughout all the milling fractions (bran, shorts, reduction flour, and break flour). The DON recoveries for each mill run ranged from 90 to 98%. These samples, regardless of DON concentration, also gave similar fractional distributions of DON. The greatest (21 ppm [21 micrograms/g]) concentration of DON was found in the bran, and the smallest (1 ppm) was found in the break flour. Cleaning and milling were not effective in removing DON; DON was not destroyed in the bread baked from the naturally contaminated whole wheat flour, but the effect on its concentration in the samples analyzed varied, the reduction ranging from 19 to 69%. The percent reduction found in the cleaned wheat ranged from 6 to 19%. DON concentrations in the following commercially made breads, caraway rye, seedless rye, and pumpernickel, were 45 ppb (ng/g), 39 ppb, and 0 ppb, respectively. The limits of detection by gas chromatography-mass spectrometry and high-pressure liquid chromatography for DON were 0.5 and 10 ng, respectively.     

Effect of cleaning, milling, and baking on deoxynivalenol in wheat.

Samples of wheat naturally infected by Fusarium graminearum Schwabe were obtained from mills in Oklahoma, Missouri, Kansas, and Minnesota and fields in Nebraska and Kansas in 1982; they were analyzed for deoxynivalenol (DON). The wheat was milled, and DON was found throughout all the milling fractions (bran, shorts, reduction flour, and break flour). The DON recoveries for each mill run ranged from 90 to 98%. These samples, regardless of DON concentration, also gave similar fractional distributions of DON. The greatest (21 ppm [21 micrograms/g]) concentration of DON was found in the bran, and the smallest (1 ppm) was found in the break flour. Cleaning and milling were not effective in removing DON; DON was not destroyed in the bread baked from the naturally contaminated whole wheat flour, but the effect on its concentration in the samples analyzed varied, the reduction ranging from 19 to 69%. The percent reduction found in the cleaned wheat ranged from 6 to 19%. DON concentrations in the following commercially made breads, caraway rye, seedless rye, and pumpernickel, were 45 ppb (ng/g), 39 ppb, and 0 ppb, respectively. The limits of detection by gas chromatography-mass spectrometry and high-pressure liquid chromatography for DON were 0.5 and 10 ng, respectively.