模拟酸雨对苦楝生理生态特性的影响

以盆栽一年生苦楝(Melia azedarach)为试材,4个p H梯度(5.6(CK)、4.5、3.5和2.5)的模拟酸雨每2 d喷洒叶片1次,探讨处理20、40和60 d对叶片叶绿素(Chl)含量、可溶性蛋白含量、细胞膜透性、MDA含量、抗氧化酶活性等的影响。结果表明:随处理时间的延长,可溶性蛋白含量在p H 4.5下呈先升后降趋势,最大增幅为10.3%,p H 3.5和p H 2.5呈降低趋势,最大降幅为42.9%;质膜透性和MDA含量均显著增加,最大增幅分别为84.6%和145.5%;SOD在p H 4.5下呈升高趋势,p H 3.5下先升高后降低,p H 2.5下呈降低趋势,最大增幅和降幅分别为47.9%和20.9%;CAT在p H 4.5下呈先升后降趋势,p H 3.5和p H 2.5下呈降低趋势,最大增幅和降幅分别为23.0%和27.0%;POD在p H 4.5和p H 3.5下呈升高趋势,p H 2.5呈降低趋势,最大增幅和降幅依次47.1%和17.6%;Chla、Chlb和叶绿素总量减少,最大降幅分别为39.0%、37.0%和38.3%。结合叶片的外观形态、脱落率和株高增量发现,p H 3.5下苦楝叶片变黄,脱落率显著增加(P0.05),p H 2.5下叶片严重变形,株高显著降低(P0.05),由此认为,苦楝耐酸雨的阈值大约为p H 3.5。     

环境因子及规格对菲律宾蛤仔幼贝潜沙行为的影响

作为埋栖型滩涂贝类的典型代表种类,菲律宾蛤仔Ruditapes philippinarum具有很强的潜沙行为。为了进一步了解其生态行为学,在室内实验室条件下,模拟了常见环境因子温度、盐度、p H值以及流速和规格大小对蛤仔幼贝(6—12 mm)潜沙速度的影响。结果表明,温度10—30℃,盐度25—30,p H值在6.0—9.0范围内蛤仔幼贝均能100%潜沙;在试验观察的4—5 h内,盐度由30突变至10时没有蛤仔潜沙,突变至20时有20%—30%潜沙(20℃,庄河蛤仔)或100%潜沙(15℃,福建蛤仔);p H值由8.0突变至10.0时不能潜沙;以暂养海水的温度(15或20℃)、盐度(30)和p H值(8.0)为中心,随着各个指标向两侧突变潜沙时间延长;流速为3、4和5 cm/s时,随流速增大潜沙速度加快;在规格6、9 mm和12 mm的幼贝中,以12 mm潜沙速度最快。若以半数潜沙时间(ET_(50))为判定指标,则适宜潜沙温度为15—20℃,盐度为25—30,p H值为7—9(莆田蛤仔)和8.0(庄河蛤仔)。在适宜条件下,蛤仔幼贝1 min内开始潜沙,3 min内有半数潜沙,5 min便全部潜沙。研究发现环境突变对蛤仔潜沙有明显影响,在天然海区放养蛤仔时应该注意购买地和放养海区温度、盐度和p H值的差异,并且选取10 mm以上幼贝放养效果较好。所得结论对完善菲律宾蛤仔幼贝的行为学及其底播养殖技术提供了有意义的参考。     

黑曲霉(Aspergillus niger)发酵生产木聚糖酶的pH调控策略

为了提高黑曲霉(Aspergillus niger)D08生产木聚糖酶的能力,考察了不同p H条件对菌株生长及产酶的影响,结果发现木聚糖酶发酵过程中菌体生长的最适p H与木聚糖酶合成的最适p H不同,分别为3.5和4.5。由此针对性地提出了两阶段p H控制策略:在30 h内控制p H为3.5;30 h后p H控制为4.5。结果表明:分阶段p H调控策略的实施进一步提高了菌体合成木聚糖酶的能力,木聚糖酶比酶活(2 223.38 U/m L)和生产强度(26.47U/(m L·h))分别比恒定p H 4.5时提高了14.3%和30.6%。该工艺对提高木聚糖酶活力具有一定的指导意义,为后续研究和生产奠定了良好的基础。     

pH对不同富集能力植物根际土壤溶液中镉形态的影响

为了解不同p H对土壤溶液中Cd形态分布的影响,采用Visual MINTEQ 3.0模型和阳极溶出伏安法(ASV)研究土壤p H分别为4.0、5.5、7.0和8.5时镉超富集植物东南景天和非富集植物垂盆草根际土壤溶液中Cd的形态分布。模型计算结果表明:随着p H的升高,2种植物土壤溶液中Cd2+的比例均逐渐减小,其中东南景天根际土壤溶液中Cd2+占总溶解性Cd的比例为46.1%~3.2%,垂盆草为60.9%~9.9%;当土壤p H≥5.5时,土壤溶液中Cd形态主要以有机络合态(Cd-DOM)为主;2种植物相比,4个p H水平下垂盆草土壤溶液中Cd2+比例均高于东南景天,但东南景天中有机络合态Cd所占比例较大。基于ASV法的测定结果表明:东南景天土壤溶液中电活性Cd占总溶解性Cd的比例从最小(p H 8.5时)的5.5%到最大(p H 4.0时)的79.6%,而垂盆草的变化范围为11.8%~86.7%;电活性Cd的测定结果与Visual MINTEQ 3.0模型计算结果显著相关(R2=0.80),从而互相验证了实验测量和模拟计算的可靠性。     

不同pH和温度对A型肉毒毒素结构及活性的作用

目的研究p H和温度对A型肉毒毒素结构及活性的影响。方法将A型肉毒毒素溶解于p H6.6和p H7.8的磷酸盐缓冲液(PB)中,分别采用4℃和35℃两种温度保存30天,在不同时间采用高压液相色谱(HPLC)及小鼠试验研究其结构及生物学活性的变化。结果样品1(p H6.6,4℃)的HPLC图谱30天内只呈现Ⅰ峰(复合物),毒力未见明显下降;样品2(p H7.8,4℃)则在溶解的最初便有Ⅱ峰(神经毒素)解离出来,并且随着时间的增加Ⅱ峰所占比例逐渐增大,毒力在30天内未见明显下降;样品3(p H6.6,35℃)最初只呈现Ⅰ峰,在第7天便有Ⅱ峰解离出来,第21天开始Ⅲ峰(轻链)出现并伴随着毒力的大幅下降(最初毒力的50%),30天降低至最初毒力的约40%;样品4(p H7.8,35℃)在第1天便有Ⅰ、Ⅱ、Ⅲ峰出现,伴随着毒力的大幅下降(最初毒力的50%),30天降低至最初毒力的约25%。结论采用酸性条件有利于维持A型肉毒毒素复合体的结构,碱性会破坏复合体各组分间的非共价键。不论用酸性还是碱性条件,高温度会加速复合体的解离与神经毒素二硫键的断裂,二硫键的断裂导致活性的下降。     

不同 pH 值条件下蜘蛛丝收缩与延展性能的变化

研究不同p H值条件下,蜘蛛丝拉伸性能的变化。在酸性条件下,设置p H值梯度,比较经丝、纬丝的拉伸性能;使用同样方法,在碱性条件下,比较经丝、纬丝的拉伸性能。将实验数据应用统计学中的单因素方差分析方法分析。结果表明不同p H值对这两类蛛丝的拉伸性能的变化均有显著影响:在酸性条件下,随着p H值的升高,经丝和纬丝收缩度逐渐升高;在碱性条件下,随着p H值的升高,其收缩度逐渐降低。当p H值为7时,经丝和纬丝的收缩度最高,分别为经丝(27.00±0.60)%,纬丝(28.30±0.31)%。     

土壤pH对东南景天修复镉和锌污染土壤的影响

采用盆栽方法研究重金属(Zn、Cd)2种污染水平(T1处理:Zn 1200 mg·kg-1+Cd 20 mg·kg-1;T2处理:Zn 300 mg·kg-1+Cd 2.0 mg·kg-1)、4个p H水平(4.0、5.5、7.0和8.5)下,土壤Zn、Cd有效态的变化、东南景天吸收和积累特征以及植物对土壤中Zn、Cd的去除效果。结果表明,随着p H的降低,土壤Zn、Cd的有效态含量显著增大,东南景天吸收和积累土壤Zn、Cd的效率显著提高。T1处理时东南景天生物量在p H 5.5时最大,但与其他p H处理的差异并不显著;Zn、Cd在植物地上与地下部分的含量均在p H 4.0时最大。T2处理时东南景天在p H 4.0时体内重金属含量最高,但由于植物生长受到Al和Mn等元素的毒害,此时生物量最小。东南景天对土壤重金属去除率均在p H 5.5时最高,其中T1处理时Cd、Zn去除率分别为16%和1.33%,T2处理时分别为27%和1.09%;2种污染水平土壤重金属的去除率均在p H 8.5时最小。因此,适当降低土壤p H,可有效提高植物积累和去除土壤Zn、Cd的效率。本研究为进一步利用东南景天修复重金属污染土壤、提高植物修复效率提供了科学依据。     

组胺H4 受体在胃腺癌组织中的表达及临床意义

目的:研究胃癌腺癌(gastric adenocarcinoma,GAC)中组胺H4受体的表达水平及其临床意义。方法:60例GAC组织(病例组)与配对癌旁组织(adjacent normal tissue,ANT)中应用免疫组织化学技术检测组胺H4受体的表达,应用实时荧光定量RT-PCR方法检测组胺H4受体mRNA的表达,统计分析组胺H4受体表达与临床病理特征之间的关系。结果:①胃腺癌组织中组胺H4受体蛋白的阳性表达率(11.7%)显著低于癌旁正常组织(96.7%)。②胃腺癌组织中组胺H4受体mRNA水平较癌旁组织明显降低(p<0.001)。③组胺H4受体蛋白和mRNA表达异常和肿瘤的病理分级有相关性(p=0.0027和p=0.0011),也与有无胃周淋巴结转移有关(p<0.001和p=0.0049)。结论:组胺H4受体在胃腺癌组织有表达异常,表达量与病理分期相关。组胺H4受体表达异常和组胺水平紊乱可能在胃癌发生发展过程中有重要作用。     

pH、食物和光周期对福寿螺生长发育和繁殖的影响

以7.5 g左右的成年福寿螺Pomacea canaliculata为对象,研究p H值(2.5—11.5)、光周期(24 h光照、12 h光照和无光照)和食物(喂食和不喂食)三因子的联合作用下对福寿螺生长发育和繁殖的影响。结果表明,无光照和饥饿条件下,福寿螺在酸性p H值4.5和p H值3.5试验的第24天均达到50%致死率,在碱性p H值10.5试验的第21天死亡率达到53.3%;试验第27天,无光照和饥饿条件下,p H值2.5和p H值11.5的死亡率则分别达到最大为66.7%和80%,产卵量均仅为20粒,孵化率分别低至6.06%和5.97%;24 h光照和喂食条件下,p H值7.5试验的第27天福寿螺体重增长率最高,为17.78%(而12 h光照和无光照条件下则分别仅为7.03%和5.47%),但此时产卵量只有180粒,孵化率仅为8.23%,延长孵化历时到16.6 d,而此酸度下12 h光照(最接近于自然节律),最终产卵量达到1600粒,且卵的孵化率高达84.66%,孵化历时为13.53 d。以上结果说明,福寿螺具有较强的耐酸碱和抗饥饿能力,但过酸(p H值≤3.5)和过碱(p H值≥10.5)的环境,也会严重抑制福寿螺的存活、生长发育和繁殖,特别是在福寿螺缺乏足够食物条件下,抑制作用更强;光周期对福寿螺的生长发育和繁殖影响较大,连续24 h光照会极大地刺激福寿螺的体重增长,但同时会干扰福寿螺繁殖,减少产卵量和卵的孵化率,延长孵化历时;而12 h光照在3种光照条件下最有利于福寿螺的生长发育和繁殖;完全黑暗则会严重抑制福寿螺的生长发育及降低其繁殖能力。     

水培条件下pH值对柳枝稷幼苗生长发育的影响

土壤的p H值是限制植物生长发育的一个关键因素。柳枝稷是一种可作为牧草,水土保持的多年生C4能源植物。试验在水培条件下,利用裂区试验设计,以柳枝稷品种(系)为主区,水培液p H值为副区,对反映柳枝稷幼苗生长发育状况的指标进行统计分析。结果显示,随水培液p H值的酸碱强度增大,柳枝稷不同品种(系)幼苗的分蘖数、株高、苗鲜重、根冠比、根系活力以及净光合速率都极显著降低(P0.01),而幼苗保护酶活性以及丙二醛(MDA)含量则极显著升高(P0.01)。尤其是当PH值低于5.0时,幼苗的受到的胁迫更为明显,幼苗超氧化物歧化酶(SOD)和过氧化物酶(POD)活性反而急剧下降。与酸胁迫(p H值7.0)相比,柳枝稷对碱胁迫(p H值7.0)的适应能力更强,其中以西稷2号的抗逆性表现最好。因此应用柳枝稷在边际土壤地区推广种植时,要尽量避免强酸性土壤(p H值5.0),且选用西稷2号品系较为适宜。     

Pollinator limitaton in a deceptive orchid, Pogonia japonica, on a floating peat mat

Deceptive orchid species that offer no floral rewards to pollinators often experience pollinator limitation because they. The breeding system and fruit set were investigated in order to examine pollinator limitation for a population of a deceptive orchid, Pogonia japonica , on a floating peat mat in Mizorogaike Pond, western Japan. Fruit sets for outcross-pollinated, self-pollinated and pollinator-excluded flowers were 75%, 80%, and 0%, respectively. Thus, this species was self-compatible but neither autogamous nor apogamous. The fruit set for open-pollinated flowers was 22.9% and 17.4% in 1994 and 1995, suggesting that pollinator limitation did occur in the field. Larger flowers were more likely to develop into fruit than smaller ones in open pollination (36% vs 8%). Thus, flower size seems to affect fruiting of this species. No effective visits by major pollinators such as bees, which could carry pollinia, were observed during 16.5 h of observation during daytime. Instead, thrips were often found moving on gynostemium or pollinia and circumstantial evidence that suggests thrips may partly transfer pollen in pieces out of a granular pollinium of P. japonica was obtained. Pogonia japonica should come to use thrips as a pollinator to supplement low fruit set under limited flower visitation by major pollinators.     

Light regulation of sink metabolism in tomato fruit : I. Growth and sugar accumulation

Light/dark effects on growth and sugar accumulation in tomato (Lycopersicon esculentum) fruit during early development were studied on intact plants (in vivo) and in tissue culture (in vitro). Through the use of an in vitro culture of tomato fruit, it was possible to investigate the direct effects of light on sink metabolism by eliminating the source tissue. Similar growth patterns were found in vivo and in vitro. Fruit growth in different sugars indicated that sucrose was the best source of carbon for in vitro fruit growth. Fruit growth increased as sucrose concentration increased up to 8%. Darkening the fruit decreased fruit dry weight about 40% in vivo and in vitro. The differences in the CO₂ exchange rate between light and dark grown fruit indicated that light stimulation of fruit growth was due to mechanisms other than photosynthesis. Supporting this conclusion was the fact that light intensities ranging from 40 to 160 micromoles per square meter per second had no significant influence on fruit growth, and light did not increase growth of fruit cultured with glucose or fructose as a carbon source. However, light stimulated fruit growth significantly when sucrose was used as the carbon source. Light-grown fruit took up 30% more sucrose from the same source and accumulated almost twice as much hexose and starch as dark-grown fruit. A possible expansion of an additional sink for carbon by light stimulation of starch synthesis during early development will be discussed.     

桂西峰丛岩溶山区大果枇杷引种试验初报

在典型的桂西岩溶区广西都安县三只羊乡进行‘早钟六号’和‘长虹三号’两个大果枇杷品种的引种栽培试验。结果表明,两个品种均能适应引种区的气候和环境,生长良好,而且还具有早实早熟的特性,栽种第三年有80%以上的植株开花结果,单株产量在10kg以上;两个品种每公顷产量分别为7875kg和8400kg,产值为47250元和50400元,净收入为35250元和38400元,果实品质优良。成林的枇杷园增加了林地面积,明显改善局部小气候。在桂西峰丛岩溶山区发展大果枇杷,经济效益、社会效益和生态效益显著。     

山东省的长肢林蛙种组物种

前人报道天津和山东有日本林蛙的分布,但也有学者表示怀疑。本文报道采集于山东徂徕山的该类物种。从成体量度和蝌蚪唇踟式来看,与现报道的镇海林蛙和峨眉林蛙有一定差异。该物种体型大小与峨眉林蛙相近似,唇齿式为1：2-2／111     

三种养殖模式下日本鳗鲡养成品的形质差异

随机选取池塘专养(M1)、日本沼虾套养(M2)以及水库放养(M3)3种养殖模式下培育的肛长为(25.91±3.26) cm的日本鳗鲡作为研究材料,比较了不同养殖模式下日本鳗鲡的形质指标,并采用聚类分析、主成分分析和判别分析等方法研究了3种养殖模式日本鳗鲡养成品的差异.结果表明:在所涉21项生物学指标和23项形质评价指数中,M1与M2之间具显著差异的分别为15项和14项,M1与M3之间具显著差异的分别为19项和18项,M2与M3之间具显著差异的分别为11项和8项;M1-M2、M1-M3、M2-M3之间的欧氏距离依次为1.433、3.516和2.167,均具显著差异;经主成分分析,提取到的5个特征值均大于1的主成分,累计贡献率达82.1％,其中第1主成分和第2主成分依次为与体型相关的肥瘦因子和与摄食行为相关的运动因子,后3个主成分为与营养状况有关的消化吸收因子,仅通过第1主成分便可较清晰地将3种养殖模式试验对象分开;采用逐步判别法,以判别贡献率较大的体宽/肛长、体长/肛长、净体积系数、鳔体积系数和肝系数为自变量,所建Fisher分类函数方程组可清晰区分3种模式的养殖群体,其判别准确率和综合判别准确率均为100％.     

Interactions between, Camellia japonica and its Seed Predator Curculio camelliae

Abstract Seeds of Camellia japonica are heavily attacked by Curculio camelliae. To evaluate the efficacy of fruit wall thickness against the curculio attack, correlations of fruit wall thickness with the ratio of seed survival (RSS) and with the ratio of oviposition success of the curculio beetles (ROS) were investigated on fruits collected at Camellia stands in Kinki District. While ROS exhibited negative correlations with the thickness of fruit wall in every stand, RSS showed different modes in accordance with the population density of the curculio. At low density, no significant difference was seen in RSS between trees with thicker fruit wall and those with thinner ones; the latter trees, generally bearing many fruits, had more seeds surviving than the former, generally bearing a few fruits. In high density curculio populations, RSS values showed correlation with the thickness of the fruit wall and more seeds survived in trees with thicker fruit walls. These facts suggest that two contrasting behavioral traits are present in a single species C. japonica and their efficacies differ in accordance with the curculio density.     

猴头菌子实体和固体培养菌丝体提取物化学组成及生物活性的比较

比较了猴头菌子实体和固体培养菌丝体的提取物化学成分的组成和含量的差异。研究结果表明,猴头菌子实体和培养菌丝体提取物的单糖含量分别为6.67%和6.68%,基本一致;蛋白质含量分别为12.73%和13.91%,比较接近;多糖的含量相差较大,分别为26.63%和18.71%,子实体提取物的多糖含量比培养菌丝体提取物高7.92%;而培养菌丝体中重金属的含量比子实体中的高;红外光谱分析子实体提取物的特征吸收峰显示二者在多糖构型上有差异;动物实验表明在等生药量时,猴头菌子实体提取物对大鼠胃粘膜损伤的保护作用优于培养菌丝体的提取物。研究结果表明,猴头菌子实体较培养菌丝体更合适于相应功能食品的开发。     

Genetic differences in fruit-set patterns are determined by differences in fruit sink strength and a source : sink threshold for fruit set

Background and Aims

Fruit set in indeterminate plant species largely depends on the balance between source and sink strength. Plants of these species show fluctuations in fruit set during the growing season. It was tested whether differences in fruit sink strength among the cultivars explained the differences in fruit-set patterns.

Methods

Capsicum was chosen as a model plant. Six cultivars with differences in fruit set, fruit size and plant growth were evaluated in a greenhouse experiment. Fruit-set patterns, generative and vegetative sink strength, source strength and the source : sink ratio at fruit set were determined. Sink strength was quantified as potential growth rate. Fruit set was related to total fruit sink strength and the source : sink ratio. The effect of differences observed in above-mentioned parameters on fruit-set patterns was examined using a simple simulation model.

Key Results

Sink strengths of individual fruits differed greatly among cultivars. Week-to-week fruit set in large-fruited cultivars fluctuated due to large fluctuations in total fruit sink strength, but in small-fruited cultivars, total fruit sink strength and fruit set were relatively constant. Large variations in week-to-week fruit set were correlated with a low fruit-set percentage. The source : sink threshold for fruit set was higher in large-fruited cultivars. Simulations showed that within the range of parameter values found in the experiment, fruit sink strength and source : sink threshold for fruit set had the largest impact on fruit set: an increase in these parameters decreased the average percentage fruit set and increased variation in weekly fruit set. Both were needed to explain the fruit-set patterns observed. The differences observed in the other parameters (e.g. source strength) had a lower effect on fruit set.

Conclusions

Both individual fruit sink strength and the source : sink threshold for fruit set were needed to explain the differences observed between fruit-set patterns of the six cultivars.     

Prescribed burning in a Eucalyptus woodland suppresses fruiting of hypogeous fungi, an important food source for mammals

Fruit bodies of hypogeous fungi are an important food source for many small mammals and are consumed by larger mammals as well. A controversial hypothesis that prescribed burning increases fruiting of certain hypogeous fungi based on observations in Tasmania was tested in the Australian Capital Territory to determine if it applied in a quite different habitat. Ten pairs of plots, burnt and nonburnt, were established at each of two sites prescribe-burnt in May 1999. When sampled in early July, after autumn rains had initiated the fungal fruiting season, species richness and numbers of fruit bodies on the burnt plots were extremely low: most plots produced none at all. Both species richness and fruit body numbers were simultaneously high on nonburnt plots. One of the sites was resampled a year after the initial sampling. At that time species richness and fruit body abundance were still significantly less on burnt plots than on nonburnt, but a strong trend towards fungal recovery on the burnt plots was evident. This was particularly so when numbers of fruit bodies of one species, the hypogeous agaric Dermocybe globuliformis, were removed from the analysis. This species strongly dominated the nonburnt plots but was absent from burnt plots in both years. The trend towards recovery of fruit body abundance in the burnt plots one year after the burn was much more pronounced with exclusion of the Dermocybe data. The Tasmanian-based hypothesis was based mostly on the fruiting of two fire-adapted species in the Mesophelliaceae. Neither species occurred on our plots. Accordingly, the results and conclusions of the Tasmanian study cannot be extrapolated to other habitats without extensive additional study. Implications for management of habitat for fungi and the animals that rely on the fungi as a food source are discussed.