蚕蛹多糖的碱液提取及免疫活性初步研究

以多糖含量为指标,以碱液浓度、提取温度、提取时间为实验因素和水平,采用正交实验设计,对蚕蛹多糖进行了碱液提取研究.结果表明,碱液提取蚕蛹多糖的最佳实验条件是碱液浓度0.02 mol·L-1、提取温度80℃、提取时间3 h.在此最佳实验条件下所得的蚕蛹多糖粗品中总糖含量为27.9%,氨基酸总量为35.85%,蛋白含量为38.1%.免疫活性实验显示,该多糖可以显著提高小鼠腹腔巨噬细胞吞噬指数和吞噬百分率、淋巴细胞转化率及血清溶血素,与对照组相比,差异具有显著性意义,表明蚕蛹碱提粗多糖可以明显增强小鼠的非特异性免疫、细胞免疫和体液免疫功能.     

老龙皮多糖的分离纯化及体外活性研究

地衣植物老龙皮富含多糖和三萜皂苷类化合物,是一种资源丰富的具有抗炎、抗氧化等活性的中草药。以老龙皮为原料,通过甲醇抽提脱脂、水浸提、三氯乙酸(TCA)法脱蛋白等方式粗提,然后分别采用梯度浓度乙醇分级沉淀法和DEAE-52纤维素柱层析的方法对老龙皮多粗多糖进行分级纯化。梯度浓度乙醇(乙醇质量浓度分别为15%,30%,50%和70%)分级沉淀得到4种多糖组分,以DEAE-52纤维素柱层析法洗脱得到5种老龙皮多糖组分。采用高效阴离子色谱(HPAEC)与红外光谱法(FT-IR)分析了老龙皮多糖组分的单糖组成和结构。研究结果表明,老龙皮多糖的单糖组成主要有阿拉伯糖、半乳糖、葡萄糖、甘露糖和木糖。其中,甘露糖含量最高,其次是半乳糖和葡萄糖。老龙皮多糖的红外光谱特征峰为3 417,2 911,1 659,1 400,1 026和831 cm-1。利用乙醇分级沉淀和DEAE-52纤维素柱层析洗脱所得的9种老龙皮多糖组分进行体外抗氧化活性研究,结果显示老龙皮多糖具有较强的清除DPPH自由基能力和总还原力。其中:50%质量浓度乙醇沉淀的老龙皮多糖组分的清除能力最强,清除率达80.10%; 15%质量浓度乙醇沉淀的老龙皮多糖组分的还原能力最强,其吸光值最高为0.74。     

白蜡虫多糖免疫调节与抑制肿瘤活性

采用环磷酰胺诱导免疫低下小鼠模型,通过测定模型小鼠的炭粒廓清指数、吞噬指数、胸腺指数和脾指数考察白蜡虫多糖的免疫调节能力;对接种S180瘤细胞的小鼠采用口服和注射方式提供白蜡虫多糖,以抑瘤率考察白蜡虫多糖体内抑瘤活性;以生长率为指标考察白蜡虫多糖对人白血病细胞株、人肺癌细胞株、人胃癌细胞株及人肝癌细胞株等4种肿瘤细胞的抑制作用。结果显示:白蜡虫粗多糖(Cwps)和纯化多糖(Pwps)均能明显增加免疫低下小鼠碳粒廓清指数及吞噬指数,但对胸腺指数和脾指数无改善作用;体内抑瘤试验发现,白蜡虫多糖对小鼠体内S180有明显的抑瘤效果,但对离体肿瘤细胞生长却无明显抑制作用。研究结果表明:白蜡虫多糖能增加免疫低下小鼠的非特性免疫能力,具有体内抑制肿瘤作用,但对肿瘤细胞无细胞毒作用,揭示白蜡虫多糖通过提高小鼠免疫能力达到体内抑制肿瘤的功效。     

白蜡虫多糖的提取及单糖组分分析

采用水提醇沉法对资源昆虫——白蜡虫中水溶性多糖组分进行提取,测定了提取物的多糖含量、蛋白含量和氨基酸含量;以1-苯基-3-甲基-5-吡唑啉酮(PMP)为柱前衍生化试剂,利用毛细管区带电泳(CZE)对其多糖的单糖组成及摩尔比率进行分析,对电泳缓冲液的浓度和pH值进行了优化。结果表明:白蜡虫水溶性多糖的提取率为2.1%,多糖含量为256 mg.g-1,蛋白含量为242 mg.g-1;白蜡虫多糖由葡萄糖、甘露糖及半乳糖3种单糖组成,其摩尔比为1∶0.85∶0.93。     

无患子果皮多糖微波提取工艺及抗氧化活性研究

探讨了无患子果皮多糖的微波提取工艺和体外抗氧化能力,并对多糖结构进行了初步表征。考察了微波提取温度、时间和液料比对无患子果皮多糖得率的影响,利用响应面分析法优化微波提取工艺,确定了提取的最佳工艺参数为:温度92℃,时间26 min,液料比25∶1(mL∶g),此条件下,多糖得率达3.47%。无患子果皮多糖主要由葡萄糖、木糖、半乳糖、阿拉伯糖和果糖组成,具有典型的多糖红外光谱特征。此外,通过测定无患子果皮多糖对·OH、DPPH·的清除能力评价其抗氧化活性,无患子果皮多糖以浓度依赖性方式表现出较强的抗氧化活性,且粗多糖抗氧化活性明显高于纯化多糖,无患子果皮多糖抗氧化活性与糖蛋白结构有一定的关联性。     

偃松松塔多糖的单糖组成分析及活性研究

偃松松塔经乙醇提取后,渣经热水提取、喷雾干燥、醇沉制备偃松松塔多糖(PPCP),并用苯酚硫酸法检测多糖的含量,气相色谱法测定PPCP的单糖组成。研究结果表明:PPCP是一种杂多糖,主要由阿拉伯糖、甘露糖、葡萄糖和半乳糖组成,具有典型的多糖红外光谱特征,4种单糖物质的量比为2.33∶1.00∶2.20∶1.94。通过测定PPCP清除DPPH·、·ABTS^+的能力以及还原能力评价PPCP抗氧化活性,然后通过体外实验评估其对RAW 264.7巨噬细胞免疫调节活性,结果表明:偃松松塔多糖有较强的自由基清除能力和Fe^3+还原能力,偃松松塔多糖以浓度依赖性方式表现出较强的抗氧化活性,在多糖质量浓度为2.0 g/L时,DPPH·的清除率(79.72%)达到最大,·ABTS^+清除率(39.63%)达到最大,其Fe^3+还原能力也达到最大值(0.78);松塔多糖能够刺激RAW 264.7巨噬细胞产生大量的NO,并没有对细胞增殖产生影响。     

蛹虫草固体培养菌质粗多糖提取与分离工艺研究

为探明蛹虫草固体发酵新型培养基茵质中多糖的含量及结构,并探明回流提取方法对此类培养基中多糖提取的条件。采用正交实验确定最佳提取条件,采用苯酚一硫酸法测定茵质中的多糖含量,并用阴离子交换柱进一步分离粗多糖。结果：回流提取的最佳条件为80℃下,料液比1：20回流提取2h,提取次数为3次。在此条件下多糖含量为6．93％。其DPPH清除率可达50％以上,粗多糖经阴离子柱分离得到3种不同的糖蛋白。结论：该实验方法操作简易,条件易控制,结果精准,适合此种培养基中蛹虫草多糖的测定及分离纯化。     

大苞鞘石斛中多糖DWW-1的提纯及其结构与性质分析

从大苞鞘石斛Dendrobium wardianum中分离纯化得到一种均一多糖组分DWW-1,采用化学和光谱学的方法对其理化性质及初步结构进行研究。首先采用水提醇沉方法制备大苞鞘的粗多糖,经过Sevag法除蛋白,DEAE-Cellulose和SephadexG-75柱层析分离纯化得到均一多糖DWW-1纯品。其次利用化学法、高效凝胶过滤色谱法、液相色谱法,并结合红外光谱,对DWW-1进行性质及结构分析。结果显示DWW-1为白色絮状固体,易溶于水,分子量为6.479×10~4,糖基组成为葡萄糖、糖醛酸、甘露糖、岩藻糖四种单糖;多糖糖苷键以1→4连接键为主,1→3为次;其次DWW-1具有较强DPPH自由基清除活性。初步研究结果表明从大苞鞘石斛中分离到的是一种具有抗氧化活性多糖,并简称为DWW-1。     

巨尾桉树皮总多酚的提取分离及其生物活性研究

以巨尾桉树皮为原料提取按树皮中的总多酚,通过正交试验优化了酶处理与超声波辅助联合提取法及超声波辅助提取法的工艺条件,并对抗氧化活性较强的乙酸乙酯萃取物进一步分离,通过大孔吸附树脂分离纯化制备得到11个活性组分(Fr.1~Fr.11)及1个活性单体化合物(Pu1),同时对其进行了体外抗氧化活性实验,并对Pu1进行了结构表征。研究结果表明:超声波辅助提取法的最佳工艺条件为60%乙醇、提取温度60℃、超声波作用时间50 min、料液比为1∶12(g∶mL),总多酚得率为5.12%。酶处理与超声波辅助联合提取法中最佳酶处理工艺条件为:酶溶液质量浓度0.15 g/L、酶解温度50℃、酶解时间50 min、酶溶液pH值5.0,在此基础上再经超声波辅助提取,总多酚得率为6.23%。乙酸乙酯萃取物的分离活性组分中Fr.5、Fr.6、Fr.7和Fr.8在质量浓度为24 mg/L时对DPPH·清除率大于60%,具有较好抗氧化能力,Pu1的半数抑制质量浓度(IC_(50))值为8.99 mg/L,小于对照样Vc的IC_(50)值(10.46 mg/L),说明Pu1具有显著的体外抗氧化活性。活性组分的总多酚含量与其抗氧化活性有很好的相关性(R=0.944 8,P0.000 1)。通过UV、FT-IR、MS和NMR等分析表明:化合物Pu1的相对分子质量为498,分子式为C21H_22O14,确定化合物Pu1为2'-甲氧基-六羟基联苯二酸-4-O-α-L-鼠李糖苷。     

肉桂多糖的结构分析及抗氧化活性研究

为探讨肉桂多糖的抗氧化活性,将肉桂水提物（CE）除蛋白得到粗多糖,通过纤维素DE-52离子柱和丙烯葡聚糖凝胶S-300进行分级分离得到肉桂中性多糖（CNP）。经凝胶渗透色谱（GPC）法测定CNP的相对分子质量（M_r）,柱前衍生高效液相色谱法测定肉桂中性多糖的单糖组分,通过甲基化法和核磁共振法测定其单糖的连接方式,采用体外化学模型研究CNP对DPPH·和ABTS⁺·的清除作用。研究结果表明：CNP的重均相对分子质量（M_w）为3 630;主要的单糖为葡萄糖;单糖的3种连接方式为1,4,5-Ac₃-2,3,6-Me₃-Glu、 1,5-Ac₂-2,3,4,6-Me₄-Glu、 1,5,6-Ac₃-2,3,4-Me₃-Glu。CNP清除自由基测定结果表明：在质量浓度为2 g/L时,CNP对DPPH·的清除率达到最大为84%,ABTS⁺·的清除率达到60%。虽然CNP对自由基的清...     

Growth of Phlebiopsis gigantea in wood of seven conifer species

Heterobasidion parviporum and Heterobasidion annosum are widely distributed root‐rot fungi that infect conifers throughout Europe. Infection of conifer stumps by spores of these pathogens can be controlled by treating fresh stumps with a competing non‐pathogenic fungus, Phlebiopsis gigantea. In this study, growth of three Latvian strains of P. gigantea and the biological control agent ‘Rotstop’ strain was evaluated in stem pieces of Norway spruce, Scots pine, lodgepole pine, Douglas‐fir, Weymouth pine, Siberian larch and Sitka spruce. The growth rates of one H. parviporum and one H. annosum isolate were also measured in the same stem pieces. The growth rate of P. gigantea varied greatly in wood of different conifer species. It was higher in the three pine species, lower in Norway spruce and lowest in Sitka spruce and Siberian larch, and in Douglas‐fir, this fungus did not grow. The largest area of wood occupied by P. gigantea was in lodgepole pine. Growth of Latvian isolates of P. gigantea in the wood of Pinus and Picea species was comparable to that of the Rotstop isolate. Consequently, stump treatment with local P. gigantea isolates should be recommended. However, our results suggest that Douglas‐fir stump treatment against Heterobasidion by P. gigantea may be ineffective and other stump treatment methods should be considered.     

Growth of Mixed Birch-Coniferous Stands in Relation to Pure Coniferous Stands at Similar Sites in South-eastern Norway

Mean age, mean and top heights and yield were studied in 20 mixed stands of birch ( Betula pubescens Ehrh. and B. pendula Roth) and Picea abies (L.) Karst. and nine mixed stands of birch and Pinus sylvestris L. in south-eastern Norway. Each mixed stand and the adjacent pure coniferous stand (control) were growing under the same site conditions and had not been commercially thinned. There were no significant differences in mean age at breast height or in top heights between birch and conifers in the mixed stands, while mean height was significantly higher for birch than for spruce. A growth index was calculated based on total volume and age at breast height. For the spruce sites the growth in young mixed stands (birch < 17 m) was superior to that of pure spruce, while the difference was insignificant in older stands. The growth index correlated positively with the ratio between generatively and vegetatively regenerated birch trees, and negatively with the age of the oldest species in the mixture and with site quality. For the pine sites there was no significant difference in the growth index between mixed birch-pine and pure pine stands. A mixture effect of birch on the volume yield of spruce or pine could not be demonstrated.     

Defoliation by the Needle-shortening Pine Gall Midge,Thecodiplosis brachyntera,on Pines in Central Sweden

An outbreak of the needle-shortening pine gall midge, Thecodiplosis brachyntera , occurred on Scots pine, Pinus sylvestris (L.) and lodgepole pine, P. contorta (Dougl.) in central Sweden during 1995-1998. The larval feeding of T. brachyntera kills current-year needles and heavy infestation causes severe defoliation. A pattern of fluctuating defoliation among years and sites was found on both pine species. Defoliation was evenly distributed in the crown of P. sylvestris during years of high as well as low infestation; apical whorls had as much defoliation as basal whorls. In P. contorta , however, there was a tendency for defoliation to be concentrated on branches in the most apical whorls. Growth ring increments on P. sylvestris with high levels of defoliation (71%) did not differ from trees with moderate levels (26%) of defoliation. Shoot lengths were significantly shorter, however, on heavily infested trees the year after defoliation.     

Decomposition and nutrient loss from prunings of different contour hedgerow species in tea plantations in the sloping highlands of Sri Lanka

Contour hedgerows of multipurpose tree species in the sloping tea lands of Sri Lanka are expected to reduce soil erosion and also add significant amounts of plant nutrients to the soil via periodic prunings. The objective of this experiment was to characterize the biomass decomposition pattern and quantify the amount of nutrients added through prunings of six tree species (Calliandra calothyrsus, Senna spectabilis, Euphatorium innulifolium, Flemingia congesta, Gliricidia sepium and Tithonia diversifolia) currently being used in hedgerows associated with tea. Withered leaf and stem prunings (50 g) were enclosed in 2-mm litter bags, placed at 5-cm depth and retrieved after one, three, six, nine and 12 weeks. Loss of initial dry weight, N, P and K was measured. Single exponential decay function adequately described both dry weight and nutrient loss. Tree species differed significantly in their rate of breakdown with decomposition constants (k) varying from 0.0299 to 0.2006 week⁻¹ for leaves and from 0.0225 to 0.0633 week⁻¹ for stems. Gliricidia showed the highest k for leaves with the rest in the following descending order: Senna > Tithonia ≥ Euphatorium > Calliandra > Flemingia. A similar pattern was observed for loss of all nutrients with Calliandra and Flemingia always having lower k values than the rest. Although N immobilization was not observed, immobilization of P and K was observed during the first week of incubation in some species, particularly in stem prunings. Annual biomass of prunings differed significantly between tree species in the following descending order: Calliandra > Senna > Flemingia > Tithonia > Gliricidia > Euphatorium. Calliandra added the greatest amount of nutrients annually to the soil with Euphatorium adding the least. Calliandra prunings provided the annual total K requirement and 49% of the N requirement of mature tea. However, none of the species provided more than 5% of the P requirement. It is concluded that among the tree species tested, Calliandra and Flemingia are the most suitable for contour hedgerows in tea plantations of this agroclimatic region because of their higher soil nutrient enrichment capacity and slower decomposition rates which would minimize leaching losses. This revised version was published online in June 2006 with corrections to the Cover Date.     

Effects of Seed Weight and Seed Type on Early Seedling Growth of Pinus sylvestris under Harsh and Optimal Conditions

The effects of seed weight and seed type on seedling growth of Pinus sylvestris (L.) were studied by seeding individually weighed orchard and stand seed in different mixtures under harsh (direct seeding in field) and optimal (seeding in nursery) conditions. In the nursery experiment an increase in the seed weight from 3 to 7 mg increased the seedling height by 10-27% and total weight by 27-113%, and decreased the height/diameter ratio by 5-6% after 2 yrs. With elimination of seed weight effects, orchard seedlings were 2% taller than stand seedlings in year 2. Without elimination of seed weight effects, orchard seedlings were 7-13% taller. In the field experiment an increase in the seed weight from 3 to 7 mg increased seedling height by 18-65%, stem volume by 81-274% and the number of top-buds by 23-34% in year 5. After elimination of seed weight effects, orchard seedlings were 7-13% taller than stand seedlings and without elimination of seed weight effects 20-21% taller after 5 yrs. Even after elimination of both seed weight and genetic effects orchard seedlings were 3-9% larger than stand seedlings in the field experiment. In conclusion, the influence of seed weight and seed type on growth traits and slenderness is highly significant and the influence seems to be greater in harsh conditions.     

Modelling of adequate pretwist for obtaining straight timber

Abstract

Wood in general and wooden studs in particular are often distorted owing to uneven shrinkage during the drying process in the sawmill. Twist is often the most detrimental of all types of distortion, and it is caused by spiral grain in combination with variations in moisture content. For sawmills, the objective is to produce dried, straight boards, and one method of dealing with boards with excessive spiral grain is to sort them out and then dry them in a pretwisted position to obtain straight boards after drying. A model using the finite element (FE) method for the simulation of drying twist distortions was first calibrated against laboratory experiments in which boards were dried with and without restraints and pretwists. After the calibration, the FE results were compared with industrial test results for boards that were dried without restraints or with restraints with zero pretwist, i.e. straight restraints. The FE model used an elastic–ideally plastic material model to obtain permanent deformations. The calibration was to set the yield stresses so that there was a good match between FE results and results from the laboratory experiments. The comparison between the industrial test results and the FE results showed that the FE model is capable of realistic simulations of drying boards with and without restraints and presumably also pretwists.     

Potential to harness superior nutritional qualities of exotic baobabs if local adaptation can be conferred through grafting

Baobab leaves form an important part of the local diet in Sahel countries and elsewhere in Africa. Existing leaf nutritional data and agroforestry performance information are based solely on Adansonia digitata L., the baobab of continental Africa. The introduction potential of Adansonia species from the center of diversity in Madagascar and from Australia remains untapped. To assess this potential, the mineral contents and B₁ and B₂ vitamin levels of dried baobab leaves were determined for five-year old trees of A. digitata, A. gibbosa (A. Cunn.) Guymer ex D. Baum, A. rubrostipa Jum. & H. Perrier (syn. A. fony Baill.), A. perrieri Capuron and A. za Baill. grown in an introduction trial in Mali. Nutritional data were evaluated against survival and vigor to identify promising germplasm. Leaf vitamin and crude protein contents were highest in the Madagascar species, especially A. rubrostipa (B₁ 88 mg 100 g⁻¹, B₂ 187 mg 100 g⁻¹, protein 20.7% dry weight). However, the local species far outperformed the introductions in survival, tree height, basal diameter and resistance to termites. We suggest grafting as a way of harnessing the vigor of well-adapted local baobab varieties to the superior nutritional profiles of A. rubrostipa and others. Cross-species grafting tests in Adansonia were successful, thus creating new agroforestry possibilities with different scion/rootstock combinations.     

Boron in forest trees and forest ecosystems

This review critically examines the role of boron (B) in forests in view of recent findings on B nutrition and the continuing occurrence of B deficiency. Many perceptions about the role of B in plants and its uptake and mobility have been altered since the last review on B in forest trees in 1990. Now there is evidence for a fundamental role of B in the formation of the pectic structure in primary cell walls in plants, and further roles in membrane function are being explored. In plants, channel-mediated B uptake, active B uptake and B uptake by mycorrhizas have been shown, B transporters have been identified, and B retranslocation has been shown. We explore these findings and their consequences on forest trees and on ecosystems that they dominate. Particular emphasis is placed on B retranslocation and B in mycorrhizal symbiosis, given their importance in trees.     

Survival and Growth of Picea abies Regeneration after Shelterwood Removal with Single- and Double-grip Harvester Systems

Three stands in Sweden were followed for 7 yrs to study the survival and growth of Norway spruce [Picea abies (L.) Karst.] regeneration after shelterwood removal with single- and double-grip harvester systems. The height of all seedlings within circular plots was recorded before and after final cutting. The tallest seedling and one randomly selected seedling on each circular plot were permanently marked and their annual height growth was measured each year during the period 1993-1999. No significant differences between single- and double-grip harvester systems were found with respect to their effects on regeneration density, survival or annual height growth. The annual height growth of the individual seedlings after shelterwood removal was significantly correlated with seedling height before shelterwood removal. Significant differences were found in annual height growth between seedlings with high and low vitality. Logging damage did not affect the annual height growth. Several practical conclusions were drawn. First, the choice of harvester system does not affect seedling height growth or survival after shelterwood removal. Secondly, the removal of a 200 m³ shelterwood with 200 stems ha^-1 does not seem to constitute a serious problem for seedling survival and growth. Finally, estimated vitality and seedling height both seem to be fairly good predictors of postrelease survival and growth.     

Development of Pinus sylvestris Main Stems Following Three Different Precommercial Thinning Methods in a Mixed Stand

Reducing competition by point cleaning may be an attractive alternative to conventional precommercial thinning in forestry. In this study, survival and development of main stems of Scots pine (Pinus sylvestris L.) following point cleaning were examined in a mixed stand of mainly Scots pine and birch (Betula pendula Roth and Betula pubescens Ehrh.) in northern Sweden. Treatments studied were: no precommercial thinning, conventional precommercial thinning, point cleaning of all secondary stems, and point cleaning of only the secondary stems that were higher than the main stem, within a radius of 0.8 m from the main stem, respectively. A randomised complete block design with three replicates was used. Measurements taken 13 growing seasons after these treatments showed that conventional precommercial thinning was the best treatment for retaining Scots pines as main stems. However, conventional precommercial thinning resulted in the poorest timber quality of the remaining Scots pines in terms of stem taper, thickest branch diameter and relative live crown height. In conclusion, point cleaning has to be followed by a complementary cleaning operation if the objective is to retain Scots pines as main stems in such mixed stands.