Alpha-amylase/subtilisin Inhibitor Levels in Australian Barleys

An enzyme-linked immunosorbent assay (ELISA) was used to determine the bifunctional alpha-amylase/subtilisin inhibitor (BASI) content of barley grain from 11 cultivars grown in six diverse locations in Australia. The inhibitor ranged from 119 to 254 μg/g in 57 barley samples. Genotype had a significant (P<0·05) effect on BASI content but there was no effect due to environment. Total protein varied independently of BASI and was influenced by environment and genotype. BASI content was higher (P<0·05) in malting barley than in feed barley and was correlated positively (r=0·29;P<0·05) with alpha-amylase activity in corresponding malts. The ELISA used monoclonal and polyclonal antibodies raised against purified BASI. In immunoblot analysis the monoclonal antibody showed high specificity for the inhibitor in barley and also detected the inhibitor in wheat. Low levels of inhibitor (mean 3·2 μg/g) were found in 12 Australian wheat cultivars using the ELISA developed for barley. The assay had a linear working range of 5–50 ng/mL with a detection limit of 2 ng/mL. Reproducibility between assays was good (CV=4·9%) but mean recoveries were high, ranging from 116–129% when purified inhibitor was added to barley extracts. The ELISA may have useful applications in brewing research and barley breeding programmes.     

缺失SBTi—A2大豆杂交后代品系籽粒化学成分分析

对一个杂交组合后代１０个稳定缺失胰蛋白酶抑制剂（ＳＢＴｉ－Ａ２）品系及其亲本籽粒化学成分组成进行的分析比较表明，大豆籽粒中缺失ＳＢＴｉ－Ａ２对其蛋白质含量及天门冬氨酸、甘氨酸和丙氨酸含量有一定影响，表现为缺失ＳＢＴｉ－Ａ２品系显著低于高亲和双亲平均值；而对其他氨基酸和脂肪含量及脂肪酸组成基本没有显著的影响。     

Purification and Trypsin Inhibitor Activity of a Sporamin B from Sweet Potato （Ipomoea batatas Lam. 55-2）

Sporamin is a soluble protein in sweet potato, and falls into two distinct homology groups, subfamilies A and B. In this research, a sporamin B was purified and its amino acid sequences, trypsin inhibitor activity （Ti activity） were analyzed. This sporamin B was isolated from sweet potato tubers [Ipomoea batatas （L.） Lam cv. 55-2] through extraction of the water-soluble fraction, dialysis, ultrafiltration and ion-exchange chromatography. Homology determined by polyacrylamide gel electrophoresis showed that mainly one bond appeared in gel after being reduced by SDS （sodium dodecyl sulfate）, or by SDS and 2-mercaptoethanol, or in native situation. By comparing the data of the polypeptide mass Matrix-assisted laser desorption/ionization time-of-flight （MALDI-TOF） mass spectrometry with those of the mass of the theoretical amino acid sequences from NCBI protein database, it was revealed that it was Q40091｜Q40091_IPOBA, sweet potato sporamin B - Ipomoea Batatas （sweet potato） （Batate）. The sequence coverage was 70.6%. N-terminal sequence was SETPV （Ser-Glu-Thr-Pro-Val）. There is a linear relationship between trypsin inhibitor activity （Ti activity） and amounts of this sporamin B （3-18 μg mL-1）. The equation of linear regression was y = 2.5809x ＋ 17.049 （r2 = 0.9966）. There was a curvilinear relationship between Ti activity and amounts of this sporamin B （21-150 μg mL-1）. The equation of curvilinear regression is y = 14.417ln（x） ＋ 23.26 （r2 = 0.9924）. The concentration of sporamin B with Ti activity after heating at 40°C may induce part denature of this sporamin B, and there was no statistic difference after heating at 40, 50, 60°C for 20 min. Heat treatment at more than 90°C leads to a dramatic decrease of trypsin inhibitor efficiency. The results suggested that Q40091｜Q40091_IPOBA was the major sporamin B in sweet potato tubers [Ipomoea Batatas （L.） Lam cv. 55-2], which had strong Ti activity, and was stable to both thermal and DTT （DL-dithiothreitol） relatively.     

灭幼脲类杀虫剂防治森林害虫的研究进展

本文论述了灭幼脲类杀虫剂目前的种类,杀虫机理,对人、畜等的安全性,害虫产生抗药性情况及其防治对象和防治方法的研究进展。最后提出灭幼脲这种昆虫生长抑制剂防治森林害虫,具有广谱、高效、低毒、低成本和残效期长等优点,而且生态效益、社会效益和经济效益明显,具有广阔的发展前途,目前已进入实际应用阶段。     

纤维素酶抑制剂对松墨天牛消化生理的影响

以松墨天牛的消化生理为基础，研究了松墨天牛消化酶中纤维素酶的动力学特性；以现代酶学研究方法为主，结合生物测定技术，进一步研究了不同性质和不同浓度的酶抑制剂对松墨天牛成虫离体和活体纤维素酶酶活力的影响，结果表明，选用的酶抑制剂无论对分离提取的纤维素酶液和活体中的纤维素酶8都具有显著的抑制作用。饲养试验中，经0.1%酶抑制剂处理的饲料组5d死亡率为75%.ck组平均成活天数为28d。     

Nitrification and denitrification in subalpine coniferous forests of different restoration stages in western Sichuan, China

Nitrification is the biological conversion of organic or inorganic nitrogen compounds from a reduced to a more oxidized state. Denitrification is generally referred to as the microbial reduction of nitrate to nitrite and further gaseous forms of nitric oxide, nitrous oxide and molecular nitrogen. They are functionally interconnected processes in the soil nitrogen cycle that are involved in the control of long-term nitrogen losses in ecosystems through nitrate leaching and gaseous N losses. In order to better understand how nitrification and denitrification change during the process of ecosystem restoration and how they are affected by various controlling factors, gross nitrification rates and denitrification rates were determined using the barometric process separation (BaPS) technique in subalpine coniferous forests of different restoration stages. The results showed that forest restoration stage had no significant effects on gross nitrification rates or denitrification rates (One-way ANOVA (analysis of variance), p < 0.05). There was no significant difference in the temperature coefficient (Q ₁₀) for gross nitrification rate among all the forest sites (One-way ANOVA, p < 0.05). Gross nitrification rates were positively correlated with water content (p < 0.05), but not with soil pH, organic matter, total nitrogen, or C/N ratios. Denitrification rates in all the forest soils were low and not closely correlated with water content, soil pH, organic matter, or total nitrogen. Nevertheless, we found that C/N ratios obviously affected denitrification rates (p < 0.05). Results from this research suggest that gross nitrification is more responsible for the nitrogen loss from soils compared with denitrification. Translated from Journal of Plant Ecology, 2006, 30(1): 90–96 [译自: 植物生态学报]     

Soil properties under a Pinus radiata – ryegrass silvopastoral system in New Zealand. Part II. C and N of soil microbial biomass, and soil N dynamics

At present, our understanding of the dynamics of microbial biomass and soil N in silvopastoral systems is very limited. In this paper, the effects of understorey management on soil microbial C and N, net N mineralization, and net nitrification were studied in two seven-year-old radiata pine (Pinus radiata D. Don) – pasture systems, consisting of plots with and without ryegrass (Lolium perenne) as an understorey. Mini-plots (1 × 1 m) with animals excluded and herbage repeatedly clipped and removed were used for soil sampling. Three mini-plots formed a transect at each of two positions: 0.9 and 3.5 m north of the tree rows. Measurements were taken from July 1997 to June 1998 about once every 40 days. One composite sample was collected from each of two sampling depths (0–10 and 10–20 cm) at each transect position on each sampling date. Temporal and spatial variability of N mineralization rates and microbial biomass C and N was large. Net mineralization and nitrification rates were higher in the bare ground than in the ryegrass plots for a major part of the year, particularly from late spring to early fall. Net N mineralization and nitrification rates were higher in the 0–10 than in the 10–20 cm soil layers in both the ryegrass and bare ground treatments; however, the depth effect on microbial biomass C and N was only significant in the ryegrass treatment. In the surface soil layer, microbial biomass C and N were substantially greater in the ryegrass than in the bare ground plots. Soil microbial properties and activities were closely linked to pasture root activities, soil depth, and site biophysical conditions. This revised version was published online in June 2006 with corrections to the Cover Date.     

Seasonal dynamics of mineral N pools and N-mineralization in soils under homegarden trees in South Andaman,India

Agroforestry trees are now well known to play a central role in the build up of nutrients pools and their transformations similar to that of forest ecosystem, however, information on the potential of homegarden trees accumulating and releasing nitrogen (mineralization) is lacking. The present study reports seasonal variations in pool sizes of mineral N (NH₄⁺-N and NO₃⁻-N), and net N-mineralization rate in relation to rainfall and temperature under coconut (Cocos nucifera L.), clove (Eugenia caryophyllata Thunb) and nutmeg (Myristica fragrans Houtt. Nees) trees in a coconut-spice trees plantation for two annual cycles in the equatorial humid climate of South Andaman Island of India. Concentration of NH₄⁺-N was the highest during wet season (May–October) and the lowest during post-wet season (November–January) under all the tree species. On the contrary, concentration of NO₃⁻-N was the lowest in the wet season and the highest during the post-wet season. However, concentrations of the mineral N were the highest under the nutmeg and the lowest under the coconut trees. Like the pool sizes, mean annual mineralization was the highest under the nutmeg (561 mg kg⁻¹ yr⁻¹) and the lowest under the coconut trees (393 mg kg⁻¹ yr⁻¹). Rate of mineralization was the highest during the post-wet season and the lowest during the dry season (February–April) under all the tree species. High rainfall during the wet season, however, reduced the rate of nitrification under all the tree species. The mean annual mineralization was logarithmically related with rainfall amount and mean monthly temperature.     

Screening of extracts of Japanese woods for melanin biosynthesis inhibition

The effects of 120 methanol extracts prepared from bark and heartwood of 69 types of Japanese wood on the melanin production of B16 melanoma cells were examined. The melanin content of B16 melanoma cells was determined spectrophotometrically at 405nm. The extracts were also examined for their effects on cell viability. We found that the methanol extracts of Fagus crenata (buna, wood, 100μg/ml), Sapium sebiferum (Nankinhaze, wood, bark, 10μg/ml), and Zelkova serrata (keyaki, wood, 10μg/ml) greatly inhibited the melanin production of B16 melanoma cells without significant cytotoxicity. However, these extracts did not inhibit tyrosinase activity at the concentration of 100μg/ml. These findings indicate that the depigmenting mechanism of these extracts involves the suppression of some pigmenting signals in stimulating melanogenesis rather than the inhibition of tyrosinase activity. Part of this study was presented at the 53rd Annual Meeting of the Japan Wood Research Society, Fukuoka, Japan, March 2003     

林地覆盖经营对雷竹林土壤氮素形态及硝化-反硝化作用的影响

为探讨林地覆盖经营对雷竹林土壤氮素形态和硝化作用、反硝化作用的影响,选择了覆盖11、3、5 a和不覆盖(CK)4种处理的雷竹林,测定0 20 cm土层土壤全氮、铵态氮和硝态氮含量,并采用气压过程分离系统(BaPS)测定土壤总硝化速率和反硝化速率。结果表明:随着覆盖年限的增加,试验雷竹林0 20 cm土层土壤全氮含量总体呈增加趋势,覆盖雷竹林全氮含量显著高于CK;土壤铵态氮和硝态氮含量均呈倒"N"型变化,覆盖3 a雷竹林的铵态氮和硝态氮含量最高;土壤铵硝比递增,覆盖3 a后显著提高,覆盖5 a后铵态氮是雷竹林土壤无机氮库的主要存在形式;土壤总硝化速率呈下降趋势,总体上与不同形态氮素含量、铵硝比相关性不显著,且相关性强度随覆盖经营年限的增加而减弱。土壤反硝化速率在覆盖3 a及以下年限时基本为0,覆盖5 a时显著提高,达69.53 μg·kg^-1·h^-1。研究表明,林地覆盖经营对雷竹林土壤氮素形态及组分比例的影响较明显,削弱了土壤硝化作用,土壤氮素不是限制硝化作用进行的主要因子,长期覆盖经营会显著提高土壤反硝化作用,增大土壤氮素的损失。在实际生产中建议采用休闲式覆盖方式,连续覆盖时间不超过3 a。