Decreased Hardness of Dietary Fiber-Rich Foods by the Enzyme-Infusion Method

A novel technique is reported for softening plant tissues while retaining their shape by impregnating them with macerating enzymes under reduced pressure after defrosting the frozen plants. Samples were removed immediately from the enzyme solution after the freeze-infusion treatment, and the hardness was measured. Six enzymes and three enzymes were respectively chosen from 18 commercial enzymes for softening burdock roots and bamboo shoots. The tissue degradation due to impregnation of the tissues with the enzymes and the reaction time were investigated. Burdock roots and bamboo shoots were progressively softened during the reaction: the hardness reached 1.0×10⁴ N/m² or less. The water-soluble dietary fiber contents increased as a result of the freeze-infusion treatment. This softening technique, which retained the food shape, could enhance the production of food products for elderly persons and those under nursing care. Foods produced by this method can replace current minced and liquid dietary components.     

臭氧处理对圈养大熊猫食用竹笋的保鲜

<正>竹笋是大熊猫(Ailuropoda melanoleuca)最为喜爱的天然食物。竹笋相对于竹叶和竹茎含水量更丰富,粗纤维含量更低,适口性更好;大宗养分、微量元素、必需氨基酸等含量丰富(周昂等,1996;唐平等,1997;周材权等,1997),而丹宁等具有微毒性的次生代谢物含量却最少(赵晓红等,2001),更利于大熊猫对生活必需营养的吸收     

竹笋深加工及其功能活性研究进展

竹笋是一种高蛋白、低脂肪、富纤维的食品.本文综述了竹笋膳食纤维、活性多糖、含氮化合物等深加工产品的制备方法,比较了不同方法对竹笋深加工产品纯度、得率、功能活性等方面的影响;对竹笋改善肠功能、抗氧化、调节血脂血糖、消炎抗肿等方面的功能活性进行了论述;分析了目前竹笋深加工过程中存在的问题,对今后研究的方向、重点和趋势进行了展望.     

Phytochelatin synthesis and responses of antioxidants during arsenic stress in <Emphasis Type="Italic">Nasturtium officinale</Emphasis>

The induction of thiols including glutathione and phytochelatins as well as the activities of antioxidant enzymes namely superoxide dismutase isoenzymes and those enzymes involved in the ascorbate-glutathione cycle in watercress plants under arsenic stress were investigated. Arsenic concentrations and tissue type-dependent response to arsenic were assessed. Plant was capable of accumulating large amounts of arsenic in the shoots. Superoxide dismutase isoenzymes activity and phytochelatin level was higher in shoots than in roots. In roots, ascorbate levels increased significantly, while no relationship was found between ascorbate contents and arsenic tolerance in shoots. Treatment with arsenic resulted in a remarkable increase in glutathione content of roots at all of the arsenic concentrations, while in shoots, glutathione content increased by lower levels of arsenic. Differences were noted in both roots and shoots for enzymes involved in the ascorbate-glutathione cycle. These results suggest that, the strategy of tolerance to arsenic toxicity in roots of watercress plants is different from that of shoots.     

Characterization of the antioxidant system during the vegetative development of pea plants

The antioxidative system was studied during the development of pea plants. The reduced glutathione (GSH) content was higher in shoots than in roots, but a greater redox state of glutathione existed in roots compared with shoots, at least after 7 d of growth. The 3-d-old seedlings showed the highest content of oxidised ascorbate (DHA), which correlated with the ascorbate oxidase (AAO) activity. Also, the roots exhibited higher DHA content than shoots, correlated with their higher AAO activity. The activities of antioxidant enzymes were much higher in shoots than in roots. Ascorbate peroxidase (APX) activity decreased during the progression of growth in both shoots and roots, whereas peroxidase (POX) activity strongly increased in roots, reflecting a correlation between POX activity and the enhancement of growth. Catalase activity from shoots reached values nearly 3 or 4-fold higher than in roots. The monodehydroascorbate reductase (MDHAR) activity was higher in young seedlings than in more mature tissues, and in roots a decrease in MDHAR was noticed at the 11^th day. No dehydroascorbate reductase (DHAR) was detected in roots from the pea plants and DHAR values detected in seedlings and in shoots were much lower than those of MDHAR. In shoots, GR decreased with the progression of growth, whereas in roots an increase was seen on the 9^th and 11^th days. Finally, superoxide dismutase (SOD) activity increased in shoots during the progression of growth, but specific SOD activity was higher in roots than in shoots.     

铜胁迫对玉米幼苗生长、叶绿素荧光参数和抗氧化酶活性的影响

本文研究了铜(Cu)胁迫下玉米(Zea mays)幼苗生长、叶绿素含量、叶绿素荧光参数和抗氧化酶活性的变化。研究结果表明, 5~20 μmol.L-1 Cu处理10天明显抑制玉米幼苗根系生长, 并减少玉米幼苗的干物重, 以及增加玉米幼苗地上部和根系含Cu量; 玉米幼苗吸收的Cu大部分积累在根系, 在地上部分布较少。Cu处理还降低玉米叶片的叶绿素含量和Fv/Fm、ETR、qP和qy值。在10天的Cu处理期间, 根系中SOD、POD、CAT和GR活性呈现先上升后下降的趋势。而叶片中的SOD、POD、CAT和GR活性在处理前期不受Cu胁迫的显著影响, 处理后期则因Cu胁迫而增强。实验表明抗氧化酶在抵御过量Cu引起的氧化胁迫中发挥了一定的作用。     

Antioxidant Responses of Lentil to Cold and Drought Stress

The effects of cold and drought stress on antioxidant responses and growth parameters in shoots and roots of lentil (Lens culinaris M cv Sultan 1) seedlings were investigated. Ten-day-old hydroponically grown seedlings were subjected to drought and cold (4°C) stress for 5 days. The length and fresh weight of shoots decreased significantly under both stress conditions, contrary to the increase in these growth parameters for roots under the same conditions. The oxidative damage as generation of malondialdehyde and hydrogen peroxide, was markedly higher in shoots under cold. Both stress conditions caused a significant increase in malondialdehyde levels in root tissues. The increase in proline levels was more pronounced under cold stress in shoots and roots. The tested stress conditions had no significant effect on chlorophyll contents. Superoxide dismutase activity was differentially altered in shoot and root tissues under drought and cold stress. The catalase activity was higher in roots under drought stress. On the other hand, ascorbate peroxidase activity increased in root tissues under cold stress. The results indicate that improved tolerance to cold and drought stress in root and shoot tissues of lentil might be correlated to the increased capacity of antioxidative defense system.     

Effect of shade treatment on theanine biosynthesis in Camellia sinensis seedlings

Theanine synthetase (TS) is a key enzyme involved in theanine biosynthesis. In our recent study, it has been revealed that theanine biosynthesis derived from nitrogen metabolism in tea (Camellia sinensis) plants can be influenced by shading treatment. The expression patterns of CsTS protein in the roots and shoots of tea seedlings were examined by western blot using a self-prepared polyclonal antibody with high specificity and sensitivity. The effect of long-term shade treatment on the levels of theanine synthesis was also investigated using roots and shoots of tea seedlings. Levels of theanine and total free amino acids gradually increased in shoots, reaching their maximum after 22 days of treatment (DOT). The immunoblotting analysis suggested that CsTS protein levels increased gradually up to 22 DOT and expression remained at a high level, except after 1 DOT where levels were low in both roots and shoots. The increased theanine concentration we observed in the shading treatment may be due to increased nitrogen assimilation and reduced theanine catabolism under shade conditions.     

Effect of UV-C treatment on modulating antioxidative system and proline metabolism of bamboo shoots subjected to chilling stress

Bamboo shoots are highly nutritious but difficult to preserve even under low temperature since they are sensitive to chilling. In the present research, bamboo shoots were exposed to UV-C light (4.1 kJ/m²) prior to 56 days storage at 1 °C to evaluate the potential of UV-C treatment on alleviating chilling injury (CI) of bamboo shoots under cold storage. CI incidence and physiological and biochemical characteristics associated with CI were determined during storage. The results showed that UV-C treatment apparently inhibited the development of CI and resulted lower EI and MDA content than that of the control. Further investigation demonstrated that UV-C treatment increased activities of CAT, APX, GR and DPPH scavenging activity of bamboo shoots, which greatly contribute to alleviating CI. The increases in both O₂ ^? production rate and H₂O₂ content of UV-C-treated bamboo shoots were significantly delayed, PAL activity was increased which contributed to enhancing accumulation of TP, and endogenous proline synthesis was promoted, which resulted from the increased activity of P5CS and decreased PDH activity. The results above suggest that the improved antioxidative defense system and enhanced proline accumulation is the underlying mechanism that UV-C treatment enhanced chilling tolerance in bamboo shoots.     

An improved grafting technique for mature Arabidopsis plants demonstrates long-distance shoot-to-root transport of phytochelatins in Arabidopsis

Phytochelatins (PCs) are peptides that function in heavy-metal chelation and detoxification in plants and fungi. A recent study showed that PCs have the ability to undergo long-distance transport in a root-to-shoot direction in transgenic Arabidopsis (Arabidopsis thaliana). To determine whether long-distance transport of PCs can occur in the opposite direction, from shoots to roots, the wheat (Triticum aestivum) PC synthase (TaPCS1) gene was expressed under the control of a shoot-specific promoter (CAB2) in an Arabidopsis PC-deficient mutant, cad1-3 (CAB2TaPCS1/cad1-3). Analyses demonstrated that TaPCS1 is expressed only in shoots and that CAB2TaPCS1/cad1-3 lines complement the cadmium (Cd) and arsenic metal sensitivity of cad1-3 shoots. CAB2TaPCS1/cad1-3 plants exhibited higher Cd accumulation in roots and lower Cd accumulation in shoots compared to wild type. Fluorescence HPLC coupled to mass spectrometry analyses directly detected PC2 in the roots of CAB2:TaPCS1/cad1-3 but not in cad1-3 controls, suggesting that PC2 is transported over long distances in the shoot-to-root direction. In addition, wild-type shoot tissues were grafted onto PC synthase cad1-3 atpcs2-1 double loss-of-function mutant root tissues. An Arabidopsis grafting technique for mature plants was modified to obtain an 84% success rate, significantly greater than a previous rate of approximately 11%. Fluorescence HPLC-mass spectrometry showed the presence of PC2, PC3, and PC4 in the root tissue of grafts between wild-type shoots and cad1-3 atpcs2-1 double-mutant roots, demonstrating that PCs are transported over long distances from shoots to roots in Arabidopsis.     

High flexibility in diet and ranging patterns in two golden monkey (Cercopithecus mitis kandti) populations in Rwanda

Many primates exhibit behavioral flexibility which allows them to adapt to environmental change and different habitat types. The golden monkey (Cercopithecus mitis kandti) is a little-studied endangered primate subspecies endemic to the Virunga massif and the Gishwati forest in central Africa. In the Virunga massif, golden monkeys are mainly found in the bamboo forest, while in the Gishwati forest they live in mixed tropical montane forest. Here we describe and compare the diet of golden monkeys in both fragments. Over 24 consecutive months from January 2017 we used scan sampling to record feeding and ranging behavior of two Virunga groups and one Gishwati group totaling ca. 240 individuals. We also examined the phenology of bamboo and fruit trees, key seasonal food plant species for the monkeys. Golden monkeys fed on more than 100 plant species. The Virunga groups were mostly folivorous (between 72.8% and 87.16% of the diet) and fed mostly on young bamboo leaves and bamboo shoots, while 48.69% of the diet of the Gishwati group consisted of fruit from 22 different tree and shrub species. Bamboo shoots and fruit are seasonally available foods and were consumed regularly throughout the period when they were available. Despite being the smallest of the three study groups, the Gishwati group had a larger home range area (150.07 ha) compared to both Virunga groups (25.24 and 91.3 ha), likely driven by the differences in availability and distribution of fruit and bamboo in the habitats. Like other blue monkey subspecies, golden monkeys appear to have a flexible dietary strategy enabling them to adjust diet and ranging behavior to local habitats and available food resources. Additional studies and continuing conservation efforts are needed to better understand how variation in feeding and ranging ecology affects reproduction, population growth, and carrying capacity.     

Copper-induced alteration in sucrose partitioning and its relationship to the root growth of two Elsholtzia haichowensis Sun populations

Hydroponic culture was used to comparatively investigate the copper (Cu)-induced alteration to sucrose metabolism and biomass allocation in two Elsholtzia haichowensis Sun populations with one from a Cu-contaminated site (CS) and the other from a non-contaminated site (NCS). Experimental results revealed that biomass allocation preferred roots over shoots in CS population, and shoots over roots in NCS population under Cu exposure. The difference in biomass allocation was correlated with the difference in sucrose partitioning between the two populations. Cu treatment (45 μM) significantly decreased leaf sucrose content and increased root sucrose content in CS population as a result of the increased activities of leaf sucrose synthesis enzymes (sucrose phosphate synthetase and sucrose synthase) and root sucrose cleavage enzyme (vacuolar invertase), which led to increased sucrose transport from leaves to roots. In contrast, higher Cu treatment increased sucrose content in leaves and decreased sucrose content in roots in NCS population as a result of the decreased activities of root sucrose cleavage enzymes (vacuolar and cell wall invertases) that led to less sucrose transport from leaves to roots. These results provide important insights into carbon resource partitioning and biomass allocation strategies in metallophytes and are beneficial for the implementation of phytoremediation techniques.     

低氧气调包装对去壳雷笋褐变和木质化的影响

研究了在厚度为0.04 mm的聚乙烯(PE)袋内充气成分为2%O2、5%CO2和93%N2于10℃下贮藏时气调袋装去壳雷笋褐变和木质化进程.与对照相比,低氧气调包装(MAP)抑制了去壳雷笋贮藏前期丙二醛(MDA)的生成,显著抑制了过氧化物酶(POD)(P＜0.05)和苯丙氨酸解氨酶(PAL)活性(P＜0.01),最终显著抑制了笋肉的褐变(P＜0.01),显著抑制了木质素(P＜0.05)和纤维素的合成,从而延长了保鲜期.去壳雷笋的褐变可能由POD和PAL活性作用引起.POD和PAL活性的增加也可能诱导了木质素的合成.     

Changes in Enzyme Regulation during Growth of Maize: I. Progressive Desensitization of Homoserine Dehydrogenase during Seedling Growth

The sensitivity of homoserine dehydrogenase (EC 1.1.1.3) to inhibition by the feed-back modifier, l-threonine, was examined in preparations derived from etiolated shoots, roots, and lightgrown tissues of Zea mays L. var. earliking. A progressive decrease in enzyme sensitivity was observed during seedling growth. Enzyme derived from internode tissue retained a greater sensitivity to the effector than enzyme derived from apical portions of etiolated shoots, whereas enzyme from root tips was characteristically more sensitive than that prepared from mature cells of the root. Enzyme desensitization occurred rapidly during culture of excised shoots and the activities of both homoserine dehydrogenase and aspartokinase (EC 2.7.2.4) declined during shoot culture under a variety of conditions. The initial enzyme levels and the characteristic sensitivity of homoserine dehydrogenase were preserved during culture at 5 to 7 C, but desensitization was not prevented by inclusion of cycloheximide in the culture medium.Results of control experiments provide evidence that desensitization occurs in vivo. No alteration of the enzyme properties was detected during extraction or concentration of sensitive or insensitive enzyme or during coextraction of enzyme from mixed populations of different age shoots; nor was a differential distribution of inhibitors or activators indicated during assay of mixed preparations. The change in enzyme sensitivity was apparent under a variety of assay conditions and was not accompanied by changes in the apparent affinity of the enzyme for the substrate, homoserine. It is suggested that systematic changes in the regulatory characteristics of certain enzymes could be an important level of metabolic regulation during cellular differentiation.Three forms of maize homoserine dehydrogenaase were detected after acrylamide gel electrophoresis of samples derived from 72-hr shoots. Similar analysis of samples from older shoots revealed a broad asymmetric band of enzyme activity, suggesting that changes in the relative distribution of specific forms of the enzyme could be related to the growth-dependent changes in the sensitivity of maize homoserine dehydrogenase.     

慈竹的数量生态研究

 慈竹生态研究的结果如下：(1)用逐步回归分析模型分析,慈竹竹丛密度仅与土壤厚度关系密切．慈竹高度、胸径与海拔成正相关。(2)用逐步回归法分析笋生长量与气候因子间的关系,证明笋的逐日生长量与湿度,温度和降雨量有较密切关系,笋在一天内有两个生长高峰。(3)自然条件下,出笋数主要与土厚密切相关,退笋数受母竹高和出笋数所制约,好笋数主要受土厚和竹高影响。     

Arbuscular mycorrhizal influence on leaf water potential, solute accumulation, and oxidative stress in soybean plants subjected to drought stress

This study investigated several aspects related to drought tolerance in arbuscular mycorrhizal (AM) soybean plants. The investigation included both shoot and root tissues in order to reveal the preferred target tissue for AM effects against drought stress. Non-AM and AM soybean plants were grown under well-watered or drought-stressed conditions, and leaf water status, solute accumulation, oxidative damage to lipids, and other parameters were determined. Results showed that AM plants were protected against drought, as shown by their significantly higher shoot-biomass production. The leaf water potential was also higher in stressed AM plants (-1.9 MPa) than in non-AM plants (-2.5 MPa). The AM roots had accumulated more proline than non-AM roots, while the opposite was observed in shoots. Lipid peroxides were 55% lower in shoots of droughted AM plants than in droughted non-AM plants. Since there was no correlation between the lower oxidative damage to lipids in AM plants and the activity of antioxidant enzymes, it seems that first the AM symbiosis enhanced osmotic adjustment in roots, which could contribute to maintaining a water potential gradient favourable to the water entrance from soil into the roots. This enabled higher leaf water potential in AM plants during drought and kept the plants protected against oxidative stress, and these cumulative effects increased the plant tolerance to drought.     

Antioxidant Enzyme Activities in Arbuscular Mycorrhizal (<Emphasis Type="Italic">Glomus intraradices</Emphasis>) Fungus Inoculated and Non-inoculated Maize Plants Under Zinc Deficiency

A greenhouse experiment was conducted to examine the changes in antioxidant enzyme activities of arbuscular mycorrhizal (AM) fungus Glomus intraradices Schenck and Smith inoculated (M+) and non-inoculated (M−) maize (Zea mays L.) plants (variety COHM5) under varying levels of zinc (0, 1.25, 2.5, 3.75 and 5.0 mg kg⁻¹). Roots and shoots sampled at 45 days after sowing (DAS) were estimated for its antioxidant enzymes (superoxide dismutase, peroxidase) IAA oxidase, polyphenol oxidase, acid phosphatase and nutritional status especially P and Zn concentrations. Mycorrhizal inoculation significantly (P ≤ 0.01) increased all the four antioxidant enzymes in both roots and shoots at 45 DAS regardless of Zn levels. All enzyme activities except SOD increased progressively with increasing levels of Zn under M+ and M− conditions. The SOD activity got decreased in roots and shoots at 2.5 and 3.75 mg Zn kg⁻¹. Acid phosphatase activity in M+ roots and shoots were higher in all levels of Zn but the values decreased with increasing levels of Zn particularly in roots. Mycorrhizal fungus inoculated plants had higher P and Zn concentrations in both stages in comparison to non-inoculated plants. Our overall data suggest that mycorrhizal symbiosis plays a vital role in enhancing activities of antioxidant enzymes and nutritional status that enables the host plant to sustain zinc deficient conditions.