对—二甲基胺基苯甲醛测定色氨酸方法的改进

在利用潘家秀的对-二甲基胺基苯甲醛显色法测定色氨酸过程中,发现该方法对显色反应条件的选择并不完善。我们对此法作了改进,结果表明改进方法的灵敏度和准确度均有所提高。     

四种中草药抗白内障形成中晶状体脂类过氧化水平及脂类含量的变化

我们观察了中草药防治大鼠半乳糖性白内障形成中脂类含量的变化及脂类过氧化水平。结果表明,与正常晶状体相比,白内障晶状体中总脂类的含量明显降低,总胆固醇的含量及脂类过氧化水平明显升高,总脂类与总胆固醇之比明显下降。而同时分别用黄苓、石斛、菟丝子及玉蝴蝶四种中草药水煎剂灌胃的大鼠晶状体中,总胆类与总胆固醇的含量基本恢复至正常;脂类过氧化水平虽仍高于正常晶状体,但也明显低于白内障晶状体,表明脂类过氧化参与了白内障的形成,上述四种中草药具有抑制脂类过氧化的作用。     

麦红吸浆虫滞育发生和解除过程中总脂和甘油三酯含量变化

【目的】脂类与昆虫滞育密切相关。本研究旨在明确麦红吸浆虫Sitodiplosis mosellana (Géhin)滞育过程中脂类物质含量的变化规律,探讨麦红吸浆虫滞育与脂类物质变化的关系。【方法】采用香兰素硫酸显色法测定了2008年5月－2010年1月不同时间陕西杨凌养虫圃内麦红吸浆虫滞育前、滞育期及滞育解除后幼虫和蛹体内总脂和甘油三酯含量。【结果】 滞育前幼虫总脂和甘油三酯含量分别为378.12和291.67 μg/mg,显著高于整个滞育期（P<0.05）。滞育年周期中,冬季总脂和甘油三酯含量最高,翌年1月结茧幼虫二者含量分别为335.29 和275.72 μg/mg,显著高于其他季节（P<0.05）;整个滞育期间,裸露幼虫和结茧幼虫总脂和甘油三酯随季节变化趋势相同,但同期结茧幼虫含量高于裸露幼虫;滞育当年与第2年同期幼虫总脂和甘油三酯含量差异不显著（P>0.05）。滞育解除后,总脂和甘油三酯含量随着幼虫的发育和变态逐渐降低,其中中蛹和后蛹显著低于活动幼虫（P<0.05）。【结论】麦红吸浆虫滞育不同时期幼虫及蛹总脂和甘油三酯含量存在明显差异,其滞育与脂类物质的含量密切相关。     

生物材料中微量锑的比色测定法

研究含锑药物治疗某些感染性疾病(例如血吸虫病)时,需要测定生物材料中微小锑量。早年 Maren 用硫酸与硝酸混合液消化生物样品,再用蓝光碱性蕊香红(Rhodamine B,以下简称蕊香红乙)显色,制订了一种微量锑的比色测定法。由于该法具有缺点,历年来许多学者另创新法将其改进。但是所有的新方法主要是在显色方面的改进,对于时间宂长而难于掌握的消化过程,基本土仍与旧法相同。我们利     

小麦受精过程的细胞化学研究

小麦成熟胚囊卵细胞中存在较多围核分布的淀粉粒和少量散布的脂类颗粒;两个助细胞中积累很多脂类,未见有淀粉粒存在;中央细胞中存在中等量均匀分布的淀粉粒和脂类颗粒。受精时期,胚囊内各细胞中淀粉粒变化不大。精卵核融合时,卵细胞和中央细胞中的脂类分别存在一个积累高峰。合子与相应时期游离核胚乳中的脂类颗粒均较少。原胚初期,每个原胚细胞及胚乳原生质中均积累较多脂类。珠孔附近的内珠被细胞中脂类颗粒较多,并存在一个有规律的变化。在观察的所有发育时期的胚珠中,均未发现贮存蛋白质。胚珠中脂类的一系列变化可能与雌性细胞的营养、胚胎发育初期的养料及花粉管的定向生长等有关     

对纳氏试剂光度法测定水中氨氮方法的改进

对纳氏试剂分光光度法测定水和废水中氨氮方法进行了改进,在不改变反映体系pH值的前提下,减少显色水样的体积及纳氏试剂的用量,改进方法与标准方法的测定结果无显著性差异。     

麻疯树种子发育过程中脂类物质变化的显微和超微结构观察

用石蜡切片、半薄切片和超薄切片方法研究了麻疯树种子发育过程中脂类物质的变化。结果表明:脂类物质主要储存于胚乳当中,当种子发育成熟时胚乳中迅速积累了大量的油脂;种皮在发育过程中脂类物质含量较多,成熟时外种皮硬化,内种皮含有大量的油脂;种子成熟时胚中含有少量的脂类物质。细胞内脂类物质含量比较多时,内质网、线粒体、质体和高尔基体数量也会较多。种子完全成熟时进行采收加工是最为合适的。     

高中生物学教学中对"脂类代谢"的新认识

选择了《生物化学》中与高中“脂类代谢”教学相关联的内容,简述了组织中的燃料供应;脂类物质的贮藏、转运和利用过程,并说明了脂肪肝病因。力图使同行对脂类代谢有一个较全面深入的认识,有利于自身的教学设计。     

TTC－脱氢酶活性测定法的改进

以紫色非硫光合细菌、枯草芽孢杆菌为材料,改进了ＴＴＣ脱氢酶活性的测定方法。在该法中样品不需处理,在常温下用三氯甲烷代替丙酮萃取,液－液分层效果好,显色稳定但不褪色。对测定中的诸多影响因素也作了研究,确定了改进后的脱氢酶活性测定的最佳条件。     

嗜麦芽窄食单胞菌OUC_Est10全基因组测序及脂类水解酶多样性分析

[目的]本研究的目的是研究嗜麦芽窄食单胞菌OUC_Est10中脂类水解酶的多样性。[方法]使用离子交换层析、全基因组测序和异源表达三种方法研究嗜麦芽窄食单胞菌OUC_Est10中脂类水解酶的多样性。[结果]离子交换层析结果显示嗜麦芽窄食单胞菌OUC_Est10可以分泌多种脂类水解酶。通过全基因组测序,我们给出了该菌的全基因组序列,该基因组大小为4668743 bp,GC含量为66.25%。通过详细的基因组序列分析,我们从该基因组中找到33个可能具有脂类水解酶活性的假定基因。通过异源表达OUC_Est10中的5个假定脂类水解酶基因,来研究其催化特性的多样性,结果显示这些脂类水解酶具有不同的催化特性。[结论]我们证明了嗜麦芽窄食单胞菌OUC_Est10拥有多样的脂类水解酶,这暗示了它在不同领域中的应用潜力。     

Échinodermes de l'Ordovicien supérieur (Ashgill) de Sardaigne et d'Algérie

Research on the influence of sea level variations on the benthic faunas have been carried out in the Upper Ordovician of Sardinia. Study of the depositional facies and sequence analysis of the upper part (Lower Ashgill) of the Portixeddu Formation led to the identification of the sedimentary environments. Cystoids and crinoids are associated to bryozoans and brachiopods in most levels. The numerical analysis of associations and megaguilds shows that crinoids and cystoids have a higher frequency in the proximal and median facies of the upper offshore. The columnal association characterized by Conspectocrinus celticus and the coronoid Mespilocystites tregarvanicus has been discovered in the upper part of the formation. This material and complementary samples from Upper Ordovician of Sardinia and Kabylia (Algeria) bring additional data on the systematic and show the wide distribution of this fauna outside of the Ibero-armorican domain. The distribution of this echinoderm association supports a palaeogeographical position of the Ibero-armorican domain and Sardinia within the north gondwanan margin during the Lower Palaeozoic.     

Labellar micromorphology of Bifrenariinae Dressler (Orchidaceae)

BACKGROUND AND AIMS: The two closely related subtribes Bifrenariinae Dressler and Maxillariinae Benth. are easily distinguished on morphological grounds. Recently, however, molecular techniques have supported the inclusion of Bifrenariinae within a more broadly defined Maxillariinae. The present paper describes the diverse labellar micromorphology found amongst representatives of Bifrenariinae (Bifrenaria Lindl., Rudolfiella Hoehne, Teuscheria Garay and Xylobium Lindl.) and compares it with that found in Maxillaria Pabst & Dungs and Mormolyca Fenzl (Maxillariinae). METHODS: The labella of 35 specimens representing 22 species of Bifrenariinae were examined by means of light microscopy and scanning electron microscopy and their micromorphology compared with that of Maxillaria sensu stricto and Mormolyca spp. The labellar epidermis of representatives of Bifrenaria, Xylobium and Mormolyca was tested for protein, starch and lipids in order to ascertain whether this tissue is involved in the rewarding of pollinators. KEY RESULTS AND CONCLUSIONS: The labella of Bifrenaria spp. and Mormolyca spp. are densely pubescent but those of Xylobium, Teuscheria and Rudolfiella are generally papillose. However, whereas the trichomes of Bifrenaria and Mormolyca are unicellular, those found in the other three genera are multicellular. Hitherto, no unicellular trichomes have been described for Maxillaria, although the labella of a number of species secrete a viscid substance or bear moniliform, pseudopollen-producing hairs. Moniliform hairs and secretory material also occur in certain species of Xylobium and Teuscheria and these genera, together with Maxillaria, are thought to be pollinated by stingless bees (Meliponini). Differences in the labellar micromorphology of Bifrenaria and Mormolyca are perhaps related to Euglossine- and/ or bumble bee-mediated pollination and pseudocopulation, respectively. Although Xylobium and Teuscheria share a number of labellar features with Maxillaria sensu stricto, this does not necessarily reflect taxonomic relationships but may be indicative of convergence in response to similar pollinator pressures.     

Cryogenic changes in proteases and antiprotease activities of buffalo (Bubalus bubalis) and cattle (Bos taurus) semen

The postthaw motility and fertility of buffalo and cattle semen is reduced when they are cryopreserved for artificial insemination. In the present study, an attempt was made to characterize the cryogenic changes in proteases and antiprotease activities (APA) of buffalo and cattle semen because these proteolysis regulators have been reported to be associated with sperm motility and fertility. Buffalo sperm demonstrated at least two major proteases of 45 and 42 kDa and three minor proteases of 95, 52, and 33 kDa. Similarly, cattle sperm demonstrated three major proteases of 62, 45, and 42 kDa and two minor proteases of 85 and 78 kDa. Buffalo seminal plasma demonstrated at least three major proteases of 78, 68, and 62 kDa and one minor protease of 98 kDa and cattle seminal plasma demonstrated one major protease of 68 kDa and two minor proteases of 78 and 75 kDa. Except for the 45 kDa protease, most of the previously mentioned proteases were found to be metalloproteinases. Compared with fresh sperm, cryopreserved buffalo and cattle sperm demonstrated a major protease band of 52/49 kDa and the activity of this protease reduced progressively with the duration of cryopreservation. On the contrary, compared with the fresh seminal plasma, cryopreserved buffalo and cattle semen extenders displayed the presence of a new protease band of 45 kDa and demonstrated that this protease activity was leaked from buffalo and cattle cryopreserved spermatozoa. Buffalo and cattle seminal plasmas displayed at least two major APA of 86 and 26 kDa. Compared with buffalo, cattle seminal plasma demonstrated significantly greater APA. Thus, the present study demonstrated the presence of an array of proteases and APA in buffalo and cattle semen and the activities of which changed during cryopreservation. The leakage of the specific protease activity and changes in the proteases and APA might be attributed to reduced motility and fertility of cryopreserved semen in these species.     

Lipid composition of pine needle chloroplasts and apple bark tissue as affected by growth temperature and daylength changes. 1. Phospholipids

Phospholipid (PL) and fatty acid composition of chloroplasts of pine needles ( Pinus sylvestris L.) and apple bark tissue ( Malus sylvestris Mill. cv. Golden Delicious) was determined in a series of experiments in which growth temperature and daylength were changed. Trees were exposed to 0 and 20°C and to daylength conditions of 9 and 14 h. All 16 possible combinations were investigated by transfer of the trees from the original condition to each of the other conditions. There was no direct relation between cold hardiness and PL composition in apple bark and pine chloroplasts, when temperature and/or daylength were changed. PL composition seemed to be strongly determined by the sequence of the imposed sets of daylength and temperature. The effect of these environmental factors on PL composition strongly differed from that for cold hardiness. The correlation between the levels of PL (and phosphatidylcholine) and cold hardiness, as reported in the literature, was also evident in this experiment, when treatments, presenting the normal seasonal order, were compared. It seems that the yearly cycle of temperature and daylength is important in determining the PL composition of apple bark and pine chloroplasts.     

How Romanowsky stains work and why they remain valuable — including a proposed universal Romanowsky staining mechanism and a rational troubleshooting scheme

Abstract

An introduction to the nomenclature and concept of “Romanowsky stains” is followed by a brief account of the dyes involved and especially the crucial role of azure B and of the impurity of most commercial dye lots. Technical features of standardized and traditional Romanowsky stains are outlined, e.g., number and ratio of the acidic and basic dyes used, solvent effects, staining times, and fixation effects. The peculiar advantages of Romanowsky staining are noted, namely, the polychromasia achieved in a technically simple manner with the potential for stain intensification of “the color purple.” Accounts are provided of a variety of physicochemically relevant topics, namely, acidic and basic dyeing, peculiarities of acidic and basic dye mixtures, consequences of differential staining rates of different cell and tissue components and of different dyes, the chemical significance of “the color purple,” the substrate selectivity for purple color formation and its intensification in situ due to a template effect, effects of resin embedding and prior fixation. Based on these physicochemical phenomena, mechanisms for the various Romanowsky staining applications are outlined including for blood, marrow and cytological smears; G-bands of chromosomes; microorganisms and other single-cell entities; and paraffin and resin tissue sections. The common factors involved in these specific mechanisms are pulled together to generate a “universal” generic mechanism for these stains. Certain generic problems of Romanowsky stains are discussed including the instability of solutions of acidic dye–basic dye mixtures, the inherent heterogeneity of polychrome methylene blue, and the resulting problems of standardization. Finally, a rational trouble-shooting scheme is appended.     

COEVOLUTION DRIVES TEMPORAL CHANGES IN FITNESS AND DIVERSITY ACROSS ENVIRONMENTS IN A BACTERIA–BACTERIOPHAGE INTERACTION

Coevolutionary interactions are thought to play a crucial role in diversification of hosts and parasitoids. Furthermore, resource availability has been shown to be a fundamental driver of species diversity. Yet, we still do not have a clear understanding of how resource availability mediates the diversity generated by coevolution between hosts and parasitoids over time. We used experiments with bacteria and bacteriophage to test how resources affect variation in the competitive ability of resistant hosts and temporal patterns of diversity in the host and parasitoid as a result of antagonistic coevolution. Bacteria and bacteriophage coevolved for over 150 bacterial generations under high and low-resource conditions. We measured relative competitive ability of the resistant hosts and phenotypic diversity of hosts and parasitoids after the initial invasion of resistant mutants and again at the end of the experiment. Variation in relative competitive ability of the hosts was both time- and environment-dependent. The diversity of resistant hosts, and the abundance of host-range mutants attacking these phenotypes, differed among environments and changed over time, but the direction of these changes differed between the host and parasitoid. Our results demonstrate that patterns of fitness and diversity resulting from coevolutionary interactions can be highly dynamic.     

Restoration and management of riparian ecosystems: a catchment perspective

1. We propose that strategies for the management of riparian ecosystems should incorporate concepts of landscape ecology and contemporary principles of restoration and conservation. A detailed understanding of the temporal and spatial dynamics of the catchment landscape (e.g. changes in the connectivity and functions of channel, riparian and terrestrial components) is critical. 2. This perspective is based upon previous definitions of riparian ecosystems, consideration of functional attributes at different spatial scales and retrospective analyses of anthropogenic influences on river catchments. 3. Restoration strategies must derive from a concise definition of the processes to be restored and conserved, recognition of social values and commitments, quantification of ecological circumstances and the quality of background information and determination of alternatives. 4. The basic components of an effective restoration project include: clear objectives (ecological and physical), baseline data and historical information (e.g. the hydrogeomorphic setting and the disturbance regime), a project design that recognizes functional attributes of biotic refugia, a comparison of plans and outcomes with reference ecosystems; a commitment to long-term planning, implementation and monitoring and, finally, a willingness to learn from both successes and failures. 5. Particularly important is a thorough understanding of past natural disturbances and human-induced changes on riparian functions and attributes, obtained by a historical reconstruction of the catchment.     

Recent advances and prospects in Prunus virology

The stone fruit genus Prunus, within the family Rosaceae, comprises more than 230 species, some of which have great importance or value as ornamental or fruit crops. Prunus are affected by numerous viruses and viroids linked to the vegetative propagation practices in many of the cultivated species. To date, 44 viruses and three viroids have been described in the 9 main cultivated Prunus species. Seven of these viruses and one viroid have been identified in Prunus hosts within the last 5 years. This work addresses recent advances and prospects in the study of viruses and viroids affecting Prunus species, mostly concerning the detection and characterisation of the agents involved, pathogenesis analysis and the search for new control tools. New sequencing technologies are quickly reshaping the way we can identify and characterise new plant viruses and isolates. Specific efforts aimed at virus identification or data mining of high‐throughput sequencing data generated for plant genomics‐oriented purposes can efficiently reveal the presence of known or novel viruses. These technologies have also been used to gain a deeper knowledge of the pathogenesis mechanisms at the gene and miRNA expression level that underlie the interactions between Prunus spp. and their main viruses and viroids. New biotechnological control tools include the transfer of resistance by grafting, the use of new sources of resistance and the development of gene silencing strategies using genetic transformation. In addition, the application of next generation sequencing and genome editing techniques will contribute to improving our knowledge of virus–host interactions and the mechanisms of resistance. This should be of great interest in the search to obtain new Prunus cultivars capable of dealing both with known viruses and viroids and with those that are yet to be discovered in the uncertain scenario of climate change.     

Manipulation of xylem transport affects Zn and Mn transport into developing wheat grains of cultured ears

Zinc and manganese loading into developing wheat grain is little understood at present. The objective of this work was to investigate factors that may affect the rate of transport of Zn and Mn into developing wheat grain of cultured ears. Ears 18-22 days post-anthesis were cultured in solutions containing labelled Zn and Mn. The effect of additions of Cu, Fe, citrate, malate and EDTA to the culture solution was observed. The effect of humidity and awn removal as well as the sucrose status of the ears on Zn and Mn transport was also investigated. The effect of high concentration of Zn and Mn on [¹⁴C]-sucrose transport was determined. High humidity almost completely blocked transport of Zn and Mn into the grain. Awn removal reduced the transport of Zn and Mn to the lemma but not the grain. When the ears were depleted of sucrose (by maintaining them in the dark prior to labelling) transport of Zn and Mn to the grain was reduced compared to ears cultured with sucrose. The presence of Cu reduced the loading of Zn into the grain. There was little effect of Cu on Mn transport or Fe on either Zn or Mn transport. High concentrations of Zn and Mn in the culture solution did not affect [¹⁴C]-sucrose loading into the grain but loading of Zn and Mn was limited at high concentrations suggesting membrane saturation. This study demonstrates that sucrose status and humidity clearly influence the transport of Zn and Mn into the grain, and that other ions may influence Zn and Mn transport.