A comparative study on lectins from four Erythrina species

A comparison of some physicochemical and structural properties of the lectins from the seeds of different species of the genus Erythrina is presented. The amino acid compositions of E. indica, E. arborescens, E. lithosperma and E. suberosa lectins are closely similar and resemble those of E. cristagalli [Eur. J. Biochem. (1982) 123, 247–2521 and E. corallodendron [Can. J. Biochem. (1981) 59, 315–320]. They are rich in acidic and hydroxy amino acids and poor in sulphur containing amino acids. All contain valine as the only N-terminal amino acid. They are glycoproteins containing high mannose type complex oligosaccharide chains. In addition to mannose they contain arabinose, xylose, fucose, glucose and galactose. Glucosamine is the amino sugar present. E. indica, E. arborescens and E. lithosperma lectins bind to Concanavalin A-Sepharose but not to lentil and pea lectin-Sepharose indicating the presence of terminal non-reducing α-d-mannose and/or internal 2-O-α-linked mannose residues in these lectins, and the absence of α(1 → 6) linkedl-fucose residues in the core regions of the oligosaccharide moieties. These lectins are metalloproteins containing about 2 g atoms of Mn²⁺ and 3 g atoms of Ca²⁺. The M_rs of E. arborescens, E. lithosperma and E. suberosa lectins are 58 000, 57 000 and 59 000, respectively. Each lectin consists of two noncovalently bound subunits which are of identical or very similar M_rs. The UV spectra of E. indica, E. arborescens and E. lithosperma lectins have similar features and in the presence of inhibitory sugars the absorbance at 278–281 nm and 290 nm increases in all cases indicating involvement of tryptophan residue(s) in sugar binding. The properties of Erythrina lectins show striking similarities and indicate close phylogenic relationships among these lectins.     

A comparative study of germination ecology of four Papaver taxa

BACKGROUND AND AIMS: Comparative studies of closely related taxa can increase understanding of adaptations and changes in seed dormancy and germination preferences in an evolutionary perspective. For such studies, a method to describe and compare the performance of taxa in a general way is needed. The germination ecology of four Papaver taxa was studied with the aim of describing and comparing their responses to different seasonal temperature regimes. METHODS: Germination of Papaver argemone, P. rhoeas, P. dubium ssp. dubium and P. dubium ssp. lecoqii was investigated in three different artificial climates over 2.5 years. Seeds were collected in southern Sweden, and samples from different populations were used as replicates of taxa. KEY RESULTS: Despite substantial intra-taxa variation, there were clear taxon-specific responses. Most germination occurred in the warmest climate. In general, the warmer the climate the more germination occurred in autumn instead of spring. Papaver argemone, phylogenetically most distant from the other taxa, was, in contrast to the others, restricted to germinating only at lower temperatures. CONCLUSIONS: Seed dormancy and germination may be described by dormancy pattern, germination preferences and dormancy strength. The general dormancy pattern was a common feature for these taxa and therefore probably an evolutionary conservative character. Germination preferences varied between taxa, resulting in different temperature optima and intervals for germination, and dormancy strength was to some extent taxon-specific, but highly variable. The dormancy pattern explained how the taxa can perform as winter annuals in warmer climates, but mainly as summer annuals in colder climates. Hence, there is no need to interpret the within-taxon temporal differences in seedling emergence as local adaptations. In the field, an entire seed cohort will not germinate during a single season. Instead, emergence will be distributed over several seasons, regardless of local climate, weather and soil cultivation methods.     

四种植物粘液繁殖体粘液的比较研究

对百里香(Thymus serpyllum)、平车前(Plantago depressa)、盐生车前(P．maritima)、野亚麻(Linum stelleroides)进行了粘液繁殖体粘液情况比较．以在水浸和浇水条件下植物种子粘沙量的多少衡量粘液量．结果表明,对于不同浸水时间处理,野亚麻和平车前未表现明显差异,盐生车前和百里香有随浸泡时间加长而粘液溶出量增多的趋势．对于不同浇水量处理,4种植物均有随浇水量增多而粘液增多的倾向．浸泡80min后,盐生车前种子的粘液粘沙使重量达原重的60多倍,平车前种子达原重的10倍左右,百里香和野亚麻种子达原重的4～6倍左右．浇水8mm后,盐生车前种子的粘液粘沙使重量达原重的20多倍,平车前种子达原重的6～10倍左右,百里香和野亚麻种子达原重的2～7倍左右．将各种处理平均,得到各种植物粘沙种子百分率为：野亚麻67．7％,百里香94．5％,平车前97．7％,盐生车前99．5％．     

实验室培养条件下绒泡菌科四种黏菌个体发育比较研究

本文应用悬滴培养、燕麦-琼脂培养等方法及显微成像技术对绒泡菌科Physaraceae 4种黏菌（黄头绒泡菌Physarum flavicomum、淡黄绒泡菌Physarum melleum、垂头绒泡菌Physarum album、针箍菌Physarella oblonga）的个体发育特征进行比较研究,首次实现了垂头绒泡菌在实验室条件下的完整生活循环。4种黏菌孢子萌发均为V-型开裂,但萌发时间有所不同,黄头绒泡菌萌发所需时间最短,仅需5h,而针箍菌萌发所需时间最长,需要2d;针箍菌和淡黄绒泡菌形成的黏变形体均可转变为游动胞,而相同条件下黄头绒泡菌和垂头绒泡菌并未有游动胞形成;4种黏菌原生质团的生长速率不同,在光照刺激下针箍菌、淡黄绒泡菌、黄头绒泡菌和垂头绒泡菌的原生质团分别经过2-3d、2-3d、7d和13d,发育成子实体;完成孢子到孢子的整个生活史,针箍菌和淡黄绒泡菌需要25-30d,黄头绒泡菌和垂头绒泡菌需要40-45d。     

A comparative study of the functional response of four species of carnivorous stoneflies

SUMMARY 1. Comparisons were made of the functional responses of mature larvae of Perlodes microcephalus, Isoperla grammatica, Dinocras cephalotes and Perla bipunctata. Experiments were performed in stream tanks with natural substrata and glass bottoms, so that feeding could be observed above and below the substratum. There was one stonefly per tank and one of 10 prey densities between 20 and 200 larvae of either Chironomus sp. or Baetis rhodani per tank. Consumed prey were replaced in a first set of experiments but not in a second set. Additional experiments assessed intraspecific interference between larvae of each predator species (two to five predators per tank). 2. The number of prey eaten increased curvilinearly with prey density. The relationship was described by two models, a Type II instantaneous model and its integrated equivalent, for experiments with and without prey replacement, respectively. Handling time did not change significantly with prey density, and was the same for experiments with and without prey replacement. Estimates of attack rate were similar for the two models, but varied between prey type and predator species. Handling time varied considerably but was normally distributed for each prey type and predator species. Mean handling time varied for Chironomus from 39 s for Isoperla, which rarely ate a whole larva, to 57 s for Perlodes and for Baetis from 116 s for Perlodes to 167 s for Perla. All predators were more efficient at capturing Baetis, but the longer handling time for Baetis ensured that more Chironomus were eaten. It was concluded that these variations in attack rate and handling time were related to activity and growth differences between the predator species, and that experiments with and without prey replacement could both be relevant to the field, depending on how the predators searched for food. 3. In the interference experiments, mean handling time did not change with increasing predator density, but attack rate decreased curvilinearly, the decrease varying from negligible for Isoperla to marked for Perlodes. Prey capture decreased with decreasing attack rate. Therefore, interference reduced prey consumption, but this effect was negligible for Isoperla and increasingly severe in the order Dinocras, Perla and Perlodes.     

四种多孔菌子实体粗多糖抗肿瘤活性的比较研究

对粗毛纤孔菌、椭圆嗜蓝孢孔菌、火木层孔菌、木蹄层孔菌4种多孔菌子实体粗多糖成分的含量及其体内抗肿瘤活性进行了比较研究。结果表明粗毛纤孔菌子实体中的粗多糖含量为4.1%,高于其他3种多孔菌;同时,4种多孔菌子实体粗多糖对H22荷瘤小鼠均显示出一定的抗肿瘤活性,除木蹄层孔菌外,其他3种多孔菌给药剂量为500mg/mL和1 000mg/mL时抑瘤率均大于40%,其中粗毛纤孔菌子实体粗多糖抑瘤率最高,低剂量组（500mg/kg）为58.12%,高剂量组（1 000mg/kg）为47.75%。     

A comparative study of mist and bubble column reactors in the in vitro production of artemisinin

Artemisia annua hairy roots grown in nutrient mist reactors produced nearly three times as much artemisinin as roots grown in bubble column reactors, 2.64 µg/g DW and 0.98 µg/g DW, respectively.     

四个可持续发展实验区绿地系统可达性比较研究

我国可持续发展实验区所在城市均十分重视绿地系统对其可持续发展的重要支撑作用。布局合理的城市绿地系统不但能提高城市生态空间容量,也能充分满足不同位置城市居民的需求,这使得城市绿地与其被服务对象——城市居民之间的可达性成为评价城市绿地系统服务价值的重要指标。以高德公司生产的电子导航地图中居民区点和绿地系统数据为基础,采用GIS缓冲区分析法,分别探讨了我国4个有代表性的国家可持续发展实验区西城区、石景山区、绍兴市和日照市这4个城市的城市绿地系统斑块特征,以及5,5—15,15—30min时间距离内所覆盖城市居民点数量,对其绿地可达性及其服务能力进行比较分析和研究。研究结果表明:4个可持续发展实验区内的绿地系统分布均比较合理,覆盖面广,尤其是30min时间距离内可达的绿地满足了95%的住区;80%以上的住区居民可以在15min内到达周边任意绿地,为城市绿地管理部门打造"一刻钟生活圈"提供了良好的基础。但同时也发现,提供服务的绿地斑块面积比较细碎,大型绿地的配置率相对较低;而且多数绿地斑块从属于多个时间距离半径内,承受较大人口压力。最后,建议城市规划过程中,注重绿地系统与住区从时间尺度上的协调分析。此外,尝试性地采用日常生活中普遍使用的电子导航地图开展城市绿地系统可达性分析,研究结果与城市居民的生产生活密切相关,对城市绿地系统规划具有实际指导意义。     

A comparative study of four dredges used for sampling benthic macroinvertebrates in rivers

SUMMARY. After considering the large number of dredges described in the literature, four light-weight dredges were chosen for manual operation from a small boat or the bank: Irish triangular dredge, small Fast dredge, medium-sized and large Naturalist's dredges. The dredges were tested in a series of trials at three sites in two rivers. A stratified random sample (number of sampling units, n = 5) was taken at each site and the modal particle sizes at sites 1–3 were 1–2 mm (fine gravel), 64–128 mm (larger stones) and 128–256 mm, respectively. The dredges usually took a similar range of stone sizes at each site but the design of the Fast dredge excluded larger stones (>16 mm). The Irish dredge sometimes failed to operate correctly. Variations in the volume of substrata taken with each dredge were large, both between sampling units in the same sample and between samples. The latter differences were partially due to the increase in the modal size of the stones, especially between sites 1 and 2, the different sampling areas of the dredges and the depth of penetration into the substratum. Penetration depth was probably greatest for the two Naturalist's dredges, smaller for the Fast dredge and smallest for the Irish dredge. In field trials, the relative abundances of major taxa were similar for most dredges at each site; major exceptions were the Fast dredge at site 2 and the Irish dredge at site 3. There was a high variability between sampling units in the same sample and therefore a lack of precision in the estimates of the mean number of invertebrates per sample. Therefore, the dredges cannot be used as quantitative samplers for the estimation of population density. Their adequacy as qualitative samplers for the estimation of total number of taxa per sample varied considerably and maximum estimates of their efficiencies for a small sample (n= 5) were <40% for the Irish and Fast dredges, >57% for the medium-sized Naturalist's dredge and >76% for the large Naturalist's dredge. There was a clear relationship between the number of taxa and the number of invertebrates taken at each site and this relationship was well described by a power law with an exponent within the range 0.18–0.53. The number of sampling units in the sample had no significant effect on the power-law equations for each site. The power-law equation was very similar for most of the dredges at each site, the only major exception being the Fast dredge at site 1. The implications of this relationship are discussed.     

科尔沁沙地4种植物抗旱性的比较研究

对科尔沁沙地小叶锦鸡儿,紫穗槐,差巴嘎蒿和胡枝子4种植物的若干水分生理生态指标进行了测定。结果表明,小叶锦鸡儿具有低水势,高水力和束缚水／自由水比及水分利用效率,抗旱性强;紫穗槐的各项指标与小叶锦鸡儿相反,抗旱性最差;差巴嘎蒿虽然水势较高,但它的持水力高,束缚水／自由水比和水分利用效率都较高,抗旱性也较强,但次于小叶锦鸡儿;胡枝子的水势和持水力较低,束缚水／自由水比及水分利用效率一般,它的抗旱性强于紫穗槐,但比差巴嘎蒿差。     

不同种源栓皮栎幼苗水分适应及耐旱特性比较研究

在大田试验条件下系统研究了4个不同种源的栓皮栎3年生幼苗水分适应和耐旱性生理特性。在5、6、7、9月份分别测定了不同种源自然饱和亏、临界饱和亏、自然需水程度、黎明前叶水势、日最低水势以及黎明叶水势与日最低叶水势差,统计分析了不同种源、不同生长期的水分参数变化规律,并对不同种源耐旱性作出了综合评价。结果表明,综合耐旱性指数在不同种源间存在显著差异(P＜0．05)。各种源抗旱性强弱顺序为：黄龙种源＞秦岭北坡种源＞伏牛山种源＞巴山种源。     

四种天牛的核型比较研究

为弄清天牛的核型特征, 补充我国天牛染色体分类特征和天牛细胞分类学的基础研究空缺, 本文以4种沟胫天牛亚科天牛为研究对象, 选取天牛的分裂旺盛组织精巢（卵巢）和中肠, 在不同的条件下进行天牛染色体玻片的制备和观察。结果显示： 4种天牛染色体数目均为 2n = 20, 性别决定机制为Xy_p。其中, 云斑白条天牛Batocera lineolata的核型公式： 4L+5M+Xy_p, 大型染色体4对, 中型染色体5对, 性染色体为小型; 榉白背粉天牛Olenecamptus cretaceus marginatus、 中华八星粉天牛Olenecamptus octopustulatus chinensis（粉天牛属）和桑天牛Apriona germari的核型公式均为： 5L+4M+Xy_p, 大型染色体5对, 中型染色体4对, 性染色体为中型。粉天牛属的榉白背粉天牛和中华八星粉天牛的核型指数非常相近; 桑天牛的染色体公式虽然与粉天牛属相同, 但长度和着丝粒位置明显不同。     

A brief comparative survey of aerophore structure within the Filicopsida

DAVIES, K. L., 1991. A brief comparative survey of aerophore structure within the Filicopsida. A comparative account of the structure of petiolar aerophores and aerating systems within certain fern families is presented. Approximately 100 species were examined and the results suggest that the petiolar aerophore structure and its relationship to internal petiolar anatomy could prove a useful taxonomic character at the generic level.     

A comparative study of four cytochemical detection methods of concanavalin A binding sites on the cell membrane

Four different electron cytochemical methods to detect concanavalin A (ConA) binding sites on the plasma membrane of mouse fibroblasts were compared in this study. The ConA binding sites were made visible either by adding ConA, followed by horseradish peroxidase (HRP) or hemocyanin (HC), or by marking the sites with complexes of ConA with ferritin (Fer) or with micro-peroxidase (MP). HC and Fer are directly visible in the electron microscope; HRP and MP are detected by their electron-dense reaction product with diaminobenzidin and H₂O₂. Differences in sensitivity of the ConA binding sites for the different markers were found and resulted in a tentative interpretation of the labelling reactions. All experiments suggested that normal and transformed murine fibroblasts both have plasma membranes in which the binding sites can move equally well and can be induced to form clusters. These results are discussed in relation with the hypothesis that differences in clustering of ConA sites between normal and transformed cells are responsible for differences in the agglutinability by ConA of these cells.     

A comparative study on the thermal decomposition of four cereal straws in an oxidizing atmosphere

The thermal decomposition characteristics of four types (wheat, barley, oats and rye) of cereal straws were studied. Two varieties from each type of straw were used. The thermal degradation behaviours and kinetic parameters (order of reaction, activation energy and preexponential factor) of the straws were compared. Two distinct reaction zones were observed for all types and varieties of straws. Thermal degradation rates in the first reaction zone were significantly higher than those in the second reaction zone. The activation energy was in the ranges of 80–102 kJ/mol and 34–75 kJ/mol, whereas the order of reaction was in the ranges of 1·3–2·3 and 0·1–0·7 for the first and second reaction zones, respectively. The Shaw variety of oats straw had the highest activation energies (102 and 75 kJ/mol) and reaction orders (2·3 and 0·7) in both the first and second reaction zones, respectively. The lowest activation energy (80 kJ/mol) and order of reaction (1·3), in the first reaction zone, corresponded to Absolvant and Monopol wheat straws. The activation energies and reaction orders of barley and rye straws were in the ranges of 85–94 kJ/mol and 1·9–2·3, respectively. There was not any significant difference between the rate constants of the straw varieties, in the first reaction zone. However, oats straws had significantly higher rate constants in the second reaction zone as compared to the rate constants of wheat, barley and rye straws.     

A comparative ultrastructural study of pit membranes with plasmodesmata associated thickenings in four angiosperm species

Recent micromorphological observations of angiosperm pit membranes have extended the number and range of taxa with pseudo-tori in tracheary elements. This study investigates at ultrastructural level (TEM) the development of pseudo-tori in the unrelated Malus yunnanensis, Ligustrum vulgare, Pittosporum tenuifolium, and Vaccinium myrtillus in order to determine whether these plasmodesmata associated thickenings have a similar developmental pattern across flowering plants. At early ontogenetic stages, the formation of a primary thickening was observed, resulting from swelling of the pit membrane in fibre-tracheids and vessel elements. Since plasmodesmata appear to be frequently, but not always, associated with these primary pit membrane thickenings, it remains unclear which ultrastructural characteristics control the formation of pseudo-tori. At a very late stage during xylem differentiation, a secondary thickening is deposited on the primary pit membrane thickening. Plasmodesmata are always associated with pseudo-tori at these final developmental stages. After autolysis, the secondary thickening becomes electron-dense and persistent, while the primary thickening turns transparent and partially or entirely dissolves. The developmental patterns observed in the species studied are similar and agree with former ontogenetic studies in Rosaceae, suggesting that pseudo-tori might be homologous features across angiosperms.     

A comparative study of the biodegradation of the surfactant sodium dodecyltriethoxy sulphate by four detergent-degrading bacteria

The 35S-labelled metabolites produced during biodegradation of sodium dodecyltriethoxy [35S]sulphate (SDTES) by four bacterial isolates were identified and quantified. All four isolates used ether-cleavage as the predominant primary degradation pathway. In two of the organisms, the etherase system (responsible for approx. 60-70% of primary biodegradation) liberated mono-, di- and triethylene glycol monosulphates in substantial proportions, the last two esters undergoing some further oxidation to acetic acid 2-(ethoxy sulphate) and acetic acid 2-(diethoxy sulphate), respectively. For these isolates, liberation of SO4(2-) directly from SDTES was also significant (30-40%) and the organisms were shown to contain alkyl sulphatases active towards SDTES. For the remaining two isolates, etherase action was even more important (responsible for greater than 80% of primary biodegradation) and was restricted almost totally to the alkyl-ether bond to generate mainly triethylene glycol sulphate, some of which was further oxidized. Very small amounts of diethylene glycol monosulphate were also produced, but its mono-homologue, and the oxidation products of both these esters, were absent. Small amounts of inorganic sulphate (approx. 10%) were liberated by these isolates and one of them also produced compounds tentatively identified as intermediates of omega-/beta-oxidation.