Aboveground plant production and nutrient content of the vegetation in six peatlands in Alberta,Canada

We examined the effects of water level, surface water chemistry, and climatic parameters on aboveground primary plant production, and the tissue nutrient concentrations in the dominant herb species in a bog, three fens, and two marshes. In the fens, total NPP correlated best with NO ₃ ^- and total phosphorus surface water concentrations in 1993 and 1994. Total NPP in the marshes correlated best with alkalinity in 1993, and with soluble reactive phosphorus in 1994. Climatic parameters, such as mean annual growing season temperature, growing degree days, and precipitation, had the most notable effect on moss growth, whereas shrub and herb production correlated significantly with the water level relative to the moss surface. Herb production correlated positively and shrub production correlated negatively with the water level relative to the moss surface. Tissue nutrient concentrations of carbon (C), nitrogen (N), and total phosphorus (TP), and the C:N quotient in Carex lasiocarpa exhibited similar trends in the fens and the marshes. Carbon tissue concentrations in C. lasiocarpa remained unchanged, whereas N and TP tissue levels decreased throughout the growing season. In the site with the highest NPP and presumably the highest stand density, C. lasiocarpa exhibited the highest tissue N and TP levels. Furthermore, TP tissue concentrations in C. lasiocarpa were substantially higher in the marshes than in the fens. Tissue nutrient concentrations in Eriophorum vaginatum in the bog showed variable response patterns. N tissue levels increased, whereas tissue TP concentrations decreased from late June to late August. In the bog, E. vaginatum exhibited similar tissue TP levels to C. lasiocarpa in the fens; however, they were both substantially lower than those found in C. lasiocarpa from the marshes.     

A numerical phytosociological study of the summits of the majella massive (Italy)

Summary A phytosociological study of Majella's summits by the use of multivariate methods has allowed to discover the following new associations:Gnaphalio-Plantaginetum atratae on humocarbonatic soils in snowy depressions,Leontopodio-Elynetum on rendzina in wind exposed and stony places,Saxifrago-Papaveretum julici andCrepidi-Leontodontetum montani on protorendzina with gravel.Gnaphalio-Plantaginetum atratae andLeontopodio-Elynetum might be classified inElyno-Seslerietea, although the former presents character species ofSalicetea herbaceae; Saxifrago-Papaveretum julici andCrepidi-Leontodontetum montani are classified inThlaspidion stylosi (foeder. nova) ofThlaspidietea.Comparisons between some clustering methods and between ordination methods based on the mathematics of principal component analysis are discussed. The efficiency of sum of squares agglomeration when the plant communities vary in a continuum and the importance of a linearizing transformation in principal component analysis are stressed.The research was supported by a grant from the Italian CNR to Prof. D. Lausi. We wish to thank also Prof. L. Orlóci, Dr. E. van der Maarel and Prof. S. Pignatti for reading and discussing the text, and Mr. A. Zampar, S. Sedmak and T. Ubaldini for technical assistance.     

Vegetation along hydrologic, edaphic, and geochemical gradients in a high-elevation poor fen in Canaan Valley, West Virginia

Wetland plant community composition and pattern are regulated by a host of abiotic/environmental gradients and biotic factors. We used multivariate analyses to classify wetland plant communities and determine the relation of hydrologic, edaphic, and geochemical gradients on community composition and spatial distribution among 18 vegetation, hydrology, and soil sampling points in Abe Run, a botanically unique poor fen in northeastern West Virginia. We also examined the interactions of disturbance with the physical environment and species composition. A total of 179 vascular plant species were identified from sample plots. Vegetative composition and structure, dominant soil texture, and hydrology lacked the distinct concentric zonation of northern peatlands; instead, all were patchy and varied considerably over short distances. Graminoid-forb meadows with primarily silt-loam mineral horizons, greater depth to groundwater, and fewer days of inundation characterized the lower reaches of the wetland. These plots were more acidic, with absent or shallow O horizons, and lower concentrations of soil base cations (Ca, Mg, K). In the upper reaches of the wetland, mixed herb-shrub-tree dominated communities were structurally and compositionally more complex; here, organic horizons were much more prominent, peat depth ranged from 80 to 100 cm, and the average depth to water table was 10 cm less than for wells in the lower reaches of the wetland. Plots from upper transects (3–6) tended to have more shrub and tree cover, and higher concentrations of soil base cations. Much of the variability among plots in the upper and lower reaches of the wetland are consistent with beaver inundation of a large portion of the wetland during the 1980s. Multiple-response permutation procedures verified the difference (P < 0.0001) between vegetation of plots in the lower and upper reaches of the watershed. Because fens are connected to groundwater, these habitats are particularly vulnerable to disturbances, particularly those that alter existing land use and land cover. Minimization of disturbances in the surrounding watershed, controls on an excessive deer population, removal of exotic, non-native species, and control on foot traffic are all integral to maintaining the integrity of this high-value wetland.     

Halothiobacillus neapolitanus strain OSWA isolated from "The Old Sulphur Well" at Harrogate (Yorkshire, England)

The “Old Sulphur Well” has a subterranean input of water containing 5.5 mM total sulfide, which would be inhibitory to the growth of most bacteria. The obligately chemolithoautotrophic Halothiobacillus neapolitanus is a sulfur bacterium known to tolerate and metabolize high sulfide concentrations, and we report the isolation of H. neapolitanus strain OSWA from this source. Strain OSWA grows well on thiosulfate and tetrathionate as energy sources, and tolerates at least 5 mM sulfide. Its specific growth rates and yields in batch culture were 0.22 h⁻¹ and 5.3 g mol⁻¹ (thiosulfate), and 0.23 h⁻¹ and 9.5 g mol⁻¹ (tetrathionate). Its 16S rRNA gene sequence shows >99% identity to reference sequences of H. neapolitanus, and it shares morphological and physiological characteristics typical of the species. It is one of a very small number of strains of H. neapolitanus described to date, and the first to be isolated from an ancient sulfide-rich natural spa.     

A comparison of RAPD and isozyme analyses for determining the genetic relationships among Avena sterilis L. accessions

Isozyme analysis is a valuable tool for determining genetic relationships among breeding lines and populations. The recently developed DNA technologies which can assay a greater proportion of the plant genome are providing a plentiful array of additional genomic markers. The objective of this research was to compare random amplified polymorphic DNA (RAPD) versus isozyme-based estimation of relationships among 24 accessions of a hexaploid wild oat, Avena sterilis L. The accessions were evaluated for variation in 23 enzyme systems and by 21 10-mer primers. A total of 77 polymorphic isozyme bands and 115 polymorphic RAPD bands were observed. Two matrices of genetic distances were estimated based on band presence/ absence. These matrices were subsequently utilized in cluster analysis and principal coordinate analysis. Both isozymes and RAPDs were proficient at distinguishing between the 24 accessions. The correspondence between the elements of both distance matrices was moderate (r=0.36**). Nevertheless, the overall representation of relationships among accessions by cluster analysis and ordination was in considerable agreement. The two techniques contrasted most notably in pair-by-pair comparisons of relationships. RAPD analysis resulted in a more definitive separation of clusters of accessions. The most significant impact of the DNA-based markers probably will be the more accurate determination of relationships between accessions that are too close to be accurately differentiated by isozymes.The research reported in this publication was funded by the North Carolina Agricultural Research Service, the North Carolina Biotechnology Center, and by a Heisenberg Fellowship (HE 1497/3-2) provided by the German Research Council to Manfred Heun     

Analysis of the disintegrating group and gradient structure in Swiss riparian forests

The differentiation of river flood plain vegetation is predominantly determined by the inundation frequency and the type and age of the substrate. A comparison of data published in 1958 with recent relevés from all parts of Switzerland indicate that the hitherto known gradient- and group structure is disintegrating into multiple floristically isolated stands as a result of waterflow management constructions. In view of further vegetation mapping, a two-phase classification is proposed where the core of the gradients and groups is isolated and analysed first. The outliers are then re-attached to serve as possible indicators of the existence of variation not sufficiently described by the data. To structure the tedious analytical calculations involved, a hierarchical procedure has been developed.Abbreviations AOC = Analysis of concentration - CA = Correspondence analysis - PCA = Principal components analysis     

北京小龙门森林鸟类群落划分与生态分析

森林鸟类是森林陆栖脊椎动物中种类和数量最丰富的动物类群 ,它们对于促进森林天然更新、传播植物种子及花粉、控制森林害虫和害兽等方面都起着重要作用。关于小龙门林区鸟类群落结构的研究已有报道[1 ] ,但是对于小龙门林区鸟类群落的划分未见有专门报道 ,我们于 1 992年 1 0月～1 993年 2月 ,1 993年 4～ 1 2月 ,1 994年 2～ 8月对北京小龙门林区所有 8条自然沟和 1条公路进行了调查 ,目的在于了解小龙门林区不同林型、海拔等区域的鸟类种类组成和数量状况 ,探讨不同区域的鸟类群落的划分及其影响因素。1　研究地点及方法小龙门林区位于北…     

The Community Types and Biomass of Sibiraea angustata Scrub and Their Relationship with Environmental Factors in Northwestern Sichuan

Sibiraea angustata (Rehd.) Hand.-Mazz. scrub is a kind of typical and representative community on the eastern Qinghai-Tibetan Plateau, and is distributed on the subalpine and alpine belts in northwestern Sichuan with the latitude between 31~ and 34~ 47 quadrats were surveyed in the representative distributionarea of Sibiraea angustata scrub in order to probe into its types, characteristics, relationship with environmental factors and biomass structure. Combined with the quantitative classification, the result showed that Sibiraea angustata formation in the northwestern Sichuan could be divided into 4 association groups and 10 association types. Furthermore, the analysis of PCA (principal component analysis) ordination determined that the distribution of the plant communities was closely related to the moisture and organic matter content in the soil and the vertical change of heat. Meanwhile, the lowest classification unit of the community-association was most susceptible to the variation of environmental factors. The research of biomass expressed that the total biomass of the Sibiraea angustata community fluctuated between 38.99 t·hm- 2 and 47.72 t·hm-2, among which the biomass of the shrub layer and herb layer were 25.87- 32.16 t·hm-2 and 12.05 - 13.73 t·hm-2 respectively. Generally speaking, it could be concluded that on the high altitude area the biomass of the aboveground was more than that of the underground, such as the underground biomass of Sibiraea angustata community was 19.04% –42.72% more than that of the aboveground.     

Prehistoric agriculture revealed by pollen analysis,plough-marks and sediment studies at Sola,south-western Norway

In 1985 archaeological excavations at Stavanger Airport, Sola, south-western Norway, revealed evidence for five phases of human activity ranging in age from the Mesolithic to the Late Bronze Age. The two youngest phases, namely 4 and 5 which reflect agrarian activity, are considered in detail in this paper. The fourth phase, which dates to ca. 3500 B.P., contains the first evidence of animal husbandry at the site and, in the fifth phase, there is evidence for a mixed farming economy. Physical evidence of cultivation includes intersecting patterns of plough-marks and, at seven sites, pollen assemblages indicative of arable farming have been recorded. The arable fields, in which weed-rich crops of Hordeum and Triticum were grown, date to ca. 2550-2200 B.P. The fields were subsequently covered by a thick layer of aeolian sand.     

Conformational studies of a monoclonal antibody, IgG1, by chemical oxidation: structural analysis by ultrahigh-pressure LC-electrospray ionization time-of-flight MS and multivariate data analysis

We describe the development of a method in which protein oxidation by H₂O₂ followed by ultrahigh-pressure liquid chromatography (UHPLC) coupled with electrospray ionization time-of-flight mass spectrometry (ESI-ToFMS) and multivariate analysis are used to detect alterations in conformational states of proteins. In the study reported here, an IgG1 monoclonal antibody in native and denatured conformational states was oxidized by treatment with hydrogen peroxide. Peptide fragments generated by tryptic digestion were then analyzed by UHPLC-ESI-ToFMS. After reducing noise and extracting peaks from the LC–MS data using MzExplorer, software developed in-house and based on Matlab, we were able to distinguish peptides arising from the native and denatured states of the oxidized protein by principal component analysis. Peptides containing residues, which are inclined to undergo oxidation, such as methionine, are founded to be particularly important in this approach. We believe that the methodology could facilitate attempts to characterize the conformational states of recombinant monoclonal antibodies and other proteins.     

Congenital defects of the upper lateral incisors: Multivariate analysis of measurements of the other teeth,the superior arch,head and face

The survey of a French male population allowed us to ascertain 75 propositi with one or two missing ULI, 59 propositi with one or two reduced ULI and 99 controls on whom measurements (mesiodistal and buccolingual diameters) of all teeth of the superior arch are available. Principal Component Analysis gave a first estimated principal component highly correlated with each of the dental measurements or arch measurements. This size factor was eliminated by observing the plane of the second and third principal components. Strikingly different clusters of MD diameters or BL diameters were observed for the controls, the propositi missing one or two of the ULI and the propositi with reduced ULI. For the controls, the arch length is correlated with the MD molar diameters and the MD incisor diameter, the arch width being isolated from the other measurements. For the propositi with missing ULI, among the dental measurements the MD and BL diameters cluster, the arch length is isolated as are the arch widths. For the propositi with reduced ULI, the arch length is closer to the dental measurements while the widths, especially the first one, are isolated. The best discriminant measurements are the diameters of the first premolars and the canine, the first arch width and the arch length. Among controls, the arch is narrowed and shorter for the propositi with absence and wider for the propositi with reduction. Teeth measurements are always smaller in propositi.     

Seasonal variation of chemical profile of Ruta graveolens extracts and biological activity against Fusarium oxysporum,Fusarium proliferatum and Stemphylium vesicarium

Ruta graveolens L. is a plant of agricultural interest due to its biological activity against phytopathogenic microorganism. This activity has been attributed to the presence of alkaloids, furanocoumarins, terpenes and fatty acids. The accumulation of these compounds is affected by environmental factors. The aim of this work was to analyze the seasonal variation the chemical profile of rue and to evaluate the biological activity against phytopathogenic fungi. Extracts were obtained in January, April, June and September 2017, chemically characterized by GC-MS. The antifungal activity was determined by absorbance, four concentrations were evaluated: 4, 8, 16 and 32 mg/mL. In extracts from the aerial parts, fatty acids were the most abundant group in the January sample (29.7%), and alkaloids in the April and June (27.7%) samples. In extracts from the roots, alkaloids were the most abundant group in the four collections. The highest percentage of growth inhibition on Fusarium and Stemphylium was obtained with the extracts of the January sample. Ruta graveolens can be considered an alternative for the management of phytopathogenic fungi of crops of economic importance.     

Sensitivity analysis for principal stratum direct effects, with an application to a study of physical activity and coronary heart disease

Summary .  In many studies, the aim is to learn about the direct exposure effect, that is, the effect not mediated through an intermediate variable. For example, in circulation disease studies it may be of interest to assess whether a suitable level of physical activity can prevent disease, even if it fails to prevent obesity. It is well known that stratification on the intermediate may introduce a so-called posttreatment selection bias. To handle this problem, we use the framework of principal stratification ( Frangakis and Rubin, 2002 , Biometrics 58, 21–29) to define a causally relevant estimand—the principal stratum direct effect (PSDE). The PSDE is not identified in our setting. We propose a method of sensitivity analysis that yields a range of plausible values for the causal estimand. We compare our work to similar methods proposed in the literature for handling the related problem of "truncation by death."     

Navigating within thiamine diphosphate-dependent decarboxylases: Sequences,structures, functional positions,and binding sites

Thiamine diphosphate-dependent decarboxylases catalyze both cleavage and formation of C C bonds in various reactions, which have been assigned to different homologous sequence families. This work compares 53 ThDP-dependent decarboxylases with known crystal structures. Both sequence and structural information were analyzed synergistically and data were analyzed for global and local properties by means of statistical approaches (principle component analysis and principal coordinate analysis) enabling complexity reduction. The different results obtained both locally and globally, that is, individual positions compared with the overall protein sequence or structure, revealed challenges in the assignment of separated homologous families. The methods applied herein support the comparison of enzyme families and the identification of functionally relevant positions. The findings for the family of ThDP-dependent decarboxylases underline that global sequence identity alone is not sufficient to distinguish enzyme function. Instead, local sequence similarity, defined by comparisons of structurally equivalent positions, allows for a better navigation within several groups of homologous enzymes. The differentiation between homologous sequences is further enhanced by taking structural information into account, such as BioGPS analysis of the active site properties or pairwise structural superimpositions. The methods applied herein are expected to be transferrable to other enzyme families, to facilitate family assignments for homologous protein sequences.     

东乡野生稻BILs群体苗期抗旱性综合评价及其遗传分析

本研究选用旱稻、R974//R974/东乡野生稻回交重组自交系及其亲本等66份水稻材料,进行苗期抗旱性鉴定及其综合指标筛选,测定了水分胁迫下最大根长、根基数、茎长、根干重、根鲜重、根系相对含水量、叶片相对含水量、卷叶级别及干旱反复存活率等9个性状。利用主成分分析和逐步回归分析法进行苗期抗旱综合评价,结果表明株系1949最为抗旱;回归分析和相关分析表明最大根长、根数、根鲜重和根系相对含水量对抗旱性影响显著,可作为苗期抗旱性鉴定综合指标。采用综合抗旱D值进行抗旱遗传分析,表明BILs群体的苗期抗旱性表现2对独立主基因+多基因控制。结果可知,东乡野生稻可作为水稻抗旱遗传改良的宝贵资源。     

Progressive plant invasion and colonization of an area adjacent to ancient woodland at Edford Wood, Somerset, England

Edford Wood, near Holcombe in Somerset, England has a rich and varied flora. Topography and species composition indicate that much of the woodland is of ancient origin. The history of the site is complex, with the woodland long subjected to considerable human disturbance from surface mining of coal, drainage and the felling of larger trees. Documentary and other evidence has revealed that part of the wood has developed from grassland during the present century. This area of secondary woodland illustrates processes of succession as woodland plants invade.     

DNA RFLPs at a highly polymorphic locus distinguish European and African subspecies of the honey bee Apis mellifera L. and suggest geographical origins of New World honey bees

A highly polymorphic locus in the honey bee, Apis mellifera L., was detected with genomic probe pB178. Eighty-five alleles, consisting of Msp I and Dde I RFLPs, were found among the Old and New World bees tested. Forty-one Msp I and 43 Dde I restriction fragment patterns, or variants, were identified. Variants and alleles were discontinuously distributed in Old World European and African subspecies. Principal coordinate analysis of the genetic distances between the alleles resulted in the identification of three distinct groups corresponding to three groups of honey bee races with historically different geographical distributions: east European A. m. ligustica and A. m. caucasica ; west European A. m. mellifera ; and South African A. m. scutellata . The clustering of alleles into these groups is consistent with previous honey bee phylogeographic studies, employing other nuclear and mitochondrial DNA markers, which in part support the evolutionary history of the honey bee hypothesized by Ruttner based on morphometric and allozyme data. The majority of alleles in bees from the USA grouped with those found in east European bees, while other alleles grouped with alleles found in A. m. mellifera . While the majority of the alleles in neotropical bees grouped with or were identical to African alleles, other alleles grouped with alleles found in A. m. mellifera, A. m. ligustica , and A. m. caucasica . Clues to the ancestry of neotropical bees may be found in the identification of alleles that were identical or more similar to alleles found in South African and west European bees; evidence for west European ancestry has been suggested using other taxonomic characters that were not unique to west European bees. Both west European and African alleles were found in individual neotropical colonies, which may indicate that honey bee subspecies which evolved allopatrically have hybridized in the human-assisted extension of their original geographical ranges.     

Conformational,configurational, and supramolecular studies of podocephalol acetate from Lasianthaea aurea

Although podocephalol ( 1 ) and its derived acetate 2 were found in Lasianthaea podocephala four decades ago, and 1 was later detected in the essential oils of several vegetal species, its absolute configuration (AC) and conformational preferences remained to be established. The structures of ar‐himachalene 1 , now isolated from Lasianthaea aurea, and its derived acetate 2 , were herein confirmed by extensive 1D and 2D nuclear magnetic resonance (NMR) studies, while the conformational preferences of the cycloheptene was established by density functional theory (DFT) calculations, which in combination with vibrational circular dichroism measurements provided the (R) absolute configuration of the molecules. The structure and AC were further verified through the Flack and Hooft parameters calculations derived from single crystal X‐ray diffraction data of 2 . In addition, careful evaluation of the crystal data allowed observing supramolecular layers cell package, an uncommon property in natural terpenes that might have potential applications. A transmission electron microscopy analysis of crystal of 2 was also possible, providing its physical characteristics at the micrometric scale.