bluuebunny/crossref_metadata_2025 huggingface dataset:
Precise δ13C analysis of dissolved inorganic carbon in natural waters using automated headspace sampling and continuous‐flow mass spectrometry.
Authors: Torres Marta E. , Mix Alan C. , Rugh William D.
Published: April 2011

A new method is presented for automated measurement of the δ13C of the dissolved inorganic carbon in natural waters, using a Finnigan GasBench‐II headspace sampler online with a Finnigan DELTAplusXL gas‐source isotope‐ratio mass spectrometer. This technique requires a small volume (30–500 mL), analyses are rapid (~80 samples/d), and little or no manual preparation is necessary. The flexibility offered by using sample loops of various sizes permits analyses of aliquots containing 2 to 50 µg C. Based on multiple replicate measurements over a 7‐week period, the overall precision of this technique is conservatively estimated to be better than ± 0.15‰ (1 sample standard deviation), which is similar to the precision of methods in current use. This precision can be improved upon (averaging ± 0.04‰, but generally better than ± 0.07‰) by chilling the sample during equilibration at a controlled temperature of 12.0 ± 0.5°C. Standardization is provided by tank CO2 (referenced to an array of international standards) and analyses are monitored against a stock solution of reagent NaHCO3, which remains isotopically stable in powder form. NaHCO3 can be analyzed with traditional acid‐digestion methods using dual‐inlet mass spectrometry, as well as in dissolved form on the GasBench‐II. Standard NaHCO3 stock solutions made to approximate dissolved inorganic carbon concentrations in water samples are isotopically stable over a period of a several weeks.
Animal‐borne sensors successfully capture the real‐time thermal properties of ocean basins
Authors: McMahon Clive R. , Autret Emmanuelle , Houghton Jonathan D. R. , Lovell Phil , Myers Andrew E. , Hays Graeme C.
Published: April 2011

Climate change is perhaps the most pressing and urgent environmental issue facing the world today. However our ability to predict and quantify the consequences of this change is severely limited by the paucity of in situ oceanographic measurements. Marine animals equipped with sophisticated oceanographic data loggers to study their behavior offer one solution to this problem because marine animals range widely across the world's ocean basins and visit remote and often inaccessible locations. However, unlike the information being collected from conventional oceanographic sensing equipment, which has been validated, the data collected from instruments deployed on marine animals over long periods has not. This is the first long‐term study to validate in situ oceanographic data collected by animal oceanographers. We compared the ocean temperatures collected by leatherback turtles (Dermochelys coriacea) in the Atlantic Ocean with the ARGO network of ocean floats and could find no systematic errors that could be ascribed to sensor instability. Animal‐borne sensors allowed water temperature to be monitored across a range of depths, over entire ocean basins, and, importantly, over long periods and so will play a key role in assessing global climate change through improved monitoring of global temperatures. This finding is especially pertinent given recent international calls for the development and implementation of a comprehensive Earth observation system (see http://iwgeo.ssc.nasa.gov/documents.asp?s=review) that includes the use of novel techniques for monitoring and understanding ocean and climate interactions to address strategic environmental and societal needs.
Trichostatin A, a histone deacetylase inhibitor, suppresses JAK2/STAT3 signaling via inducing the promoter‐associated histone acetylation of SOCS1 and SOCS3 in human colorectal cancer cells
Authors: Xiong Hua , Du Wan , Zhang Yan‐Jie , Hong Jie , Su Wen‐Yu , Tang Jie‐Ting , Wang Ying‐Chao , Lu Rong , Fang Jing‐Yuan
Published: April 2011

Aberrant janus kinase/signal transducers and activators of transcription (JAK/STAT) signaling is involved in the oncogenesis of several cancers. Suppressors of cytokine signaling (SOCS) genes and SH2‐containing protein tyrosine phosphatase 1 (SHP1) proteins, which are negative regulators of JAK/STAT signaling, have been reported to have tumor suppressor functions. However, in colorectal cancer (CRC) cells, the mechanisms that regulate SOCS and SHP1 genes, and the cause of abnormalities in the JAK/STAT signaling pathway, remain largely unknown. The present study shows that trichostatin A (TSA), a histone deacetylase (HDAC) inhibitor, leads to the hyperacetylation of histones associated with the SOCS1 and SOCS3 promoters, but not the SHP1 promoter in CRC cells. This indicates that histone modifications are involved in the regulation of SOCS1 and SOCS3. Moreover, upregulation of SOCS1 and SOCS3 expression was achieved using TSA, which also significantly downregulated JAK2/STAT3 signaling in CRC cells. We also demonstrate that TSA suppresses the growth of CRC cells, and induces G1 cell cycle arrest and apoptosis through the regulation of downstream targets of JAK2/STAT3 signaling, including Bcl‐2, survivin and p16ink4a. Therefore, our data demonstrate that TSA may induce SOCS1 and SOCS3 expression by inducing histone modifications and consequently inhibits JAK2/STAT3 signaling in CRC cells. These results also establish a mechanistic link between the inhibition of JAK2/STAT3 signaling and the anticancer action of TSA in CRC cells. Mol. Carcinog. © 2011 Wiley Periodicals, Inc.
The status of the species Beijerinckia fluminensis Döbereiner and Ruschel 1958. Request for an Opinion
Authors: Oggerin Monike , Rubio Víctor , Marín Irma , Arahal David R.
Published: April 2011

In a previous article [Oggerin M., Arahal, D. R., Rubio, V. & Marin, I. (2009). Int J Syst Evol Microbiol
59, 2323–2328], it has been shown that strain Beijerinckia fluminensis UQM 1685T and its derived equivalent B. fluminensis CIP 106281T do not conform to the description of the type strain of Beijerinckia fluminensis Döbereiner and Ruschel 1958. Indeed, both strains were identified as members of the species Rhizobium radiobacter and exhibited marked phenotypic and genotypic differences with members of the genus Beijerinckia. It was concluded that both strains, and any other equivalents derived from them, do not descend from the nomenclatural type. Since then, our attempts to find older deposits of the type strain, hopefully derived from the original isolate, or other existing strains of Beijerinckia fluminensis that could be proposed as a neotype strain, have been in vain. It is therefore proposed that the Judicial Commission should place the name Beijerinckia fluminensis Döbereiner and Ruschel 1958 on the list of rejected names if a suitable replacement type strain or a neotype cannot be found within two years following the publication of this Request (Rule 18c).
Both the Hydrophobicity and a Positively Charged Region Flanking the C-Terminal Region of the Transmembrane Domain of Signal-Anchored Proteins Play Critical Roles in Determining Their Targeting Specificity to the Endoplasmic Reticulum or Endosymbiotic Organelles inArabidopsisCells
Authors: Lee Junho , Lee Hyunkyung , Kim Jinho , Lee Sumin , Kim Dae Heon , Kim Sanguk , Hwang Inhwan
Published: April 2011

Proteins localized to various cellular and subcellular membranes play pivotal roles in numerous cellular activities. Accordingly, in eukaryotic cells, the biogenesis of organellar proteins is an essential process requiring their correct localization among various cellular and subcellular membranes. Localization of these proteins is determined by either cotranslational or posttranslational mechanisms, depending on the final destination. However, it is not fully understood how the targeting specificity of membrane proteins is determined in plant cells. Here, we investigate the mechanism by which signal-anchored (SA) proteins are differentially targeted to the endoplasmic reticulum (ER) or endosymbiotic organelles using in vivo targeting, subcellular fractionation, and bioinformatics approaches. For targeting SA proteins to endosymbiotic organelles, the C-terminal positively charged region (CPR) flanking the transmembrane domain (TMD) is necessary but not sufficient. The hydrophobicity of the TMD in CPR-containing proteins also plays a critical role in determining targeting specificity; TMDs with a hydrophobicity value >0.4 on the Wimley and White scale are targeted primarily to the ER, whereas TMDs with lower values are targeted to endosymbiotic organelles. Based on these data, we propose that the CPR and the hydrophobicity of the TMD play a critical role in determining the targeting specificity between the ER and endosymbiotic organelles.
TEC family kinases in health and disease – loss‐of‐function of BTK and ITK and the gain‐of‐function fusions ITK–SYK and BTK–SYK
Authors: Hussain Alamdar , Yu Liang , Faryal Rani , Mohammad Dara K. , Mohamed Abdalla J. , Smith C. I. Edvard
Published: April 2011

The TEC family is ancient and constitutes the second largest family of cytoplasmic tyrosine kinases. In 1993, loss‐of‐function mutations in the BTK gene were reported as the cause of X‐linked agammaglobulinemia. Of all the existing 90 tyrosine kinases in humans, Bruton’s tyrosine kinase (BTK) is the kinase for which most mutations have been identified. These experiments of nature collectively provide a form of mutation scanning with direct implications for the several hundred endogenous signaling proteins carrying domains also found in BTK. In 2009, an inactivating mutation in the ITK gene was shown to cause susceptibility to lethal Epstein–Barr virus infection. Both kinases represent interesting targets for inhibition: in the case of BTK, as an immunosuppressant, whereas there is evidence that the inhibition of inducible T‐cell kinase (ITK) could influence the infectivity of HIV and also have anti‐inflammatory activity. Since 2006, several patients carrying a fusion protein, originating from a translocation joining genes encoding the kinases ITK and spleen tyrosine kinase (SYK), have been shown to develop T‐cell lymphoma. We review these disease processes and also describe the role of the N‐terminal pleckstrin homology–Tec homology (PH–TH) domain doublet of BTK and ITK in the downstream intracellular signaling of such fusion proteins.
Employing Site-Specific Recombination for Conditional Genetic Analysis in Sinorhizobium meliloti
Authors: Harrison Clarice L. , Crook Matthew B. , Peco Gledi , Long Sharon R. , Griffitts Joel S.
Published: April 2011

The ability to remove a genetic function from an organism with good temporal resolution is crucial for characterizing essential genes or genes that act in complex developmental programs. The rhizobium-legume symbiosis involves an elaborate two-organism interaction requiring multiple levels of signal exchange. As an important step toward probing rhizobium genetic functions with temporal resolution, we present the development of a conditional gene deletion system in
Sinorhizobium meliloti
that employs Cre/
loxP
site-specific recombination. This system enables chemically inducible and irreversible gene deletion or gene upregulation. Recombinase-mediated excision events can be positively or negatively selected or monitored by a colorimetric assay. The system may be adaptable to various bacterial species, in which recombinase activity may be placed under the control of diverse user-defined promoters. This system also shows promise for uses in promoter trapping and biosensing applications.
Genotypic Diversity of Escherichia coli in the Water and Soil of Tropical Watersheds in Hawaii
Authors: Goto Dustin K. , Yan Tao
Published: April 2011

High levels of
Escherichia coli
were frequently detected in tropical soils in Hawaii, which present important environmental sources of
E. coli
to water bodies. This study systematically examined
E. coli
isolates from water and soil of several watersheds in Hawaii and observed high overall genotypic diversity (35.5% unique genotypes). In the Manoa watershed, fewer than 9.3% of the observed
E. coli
genotypes in water and 6.6% in soil were shared between different sampling sites, suggesting the lack of dominant fecal sources in the watershed. High temporal variability of
E. coli
genotypes in soil was also observed, which suggests a dynamic
E. coli
population corresponding with the frequently observed high concentrations in tropical soils. When
E. coli
genotypes detected from the same sampling events were compared, limited sharing between the soil and water samples was observed in the majority of comparisons (73.5%). However, several comparisons reported up to 33.3% overlap of
E. coli
genotypes between soil and water, illustrating the potential for soil-water interactions under favorable environmental conditions. In addition, genotype accumulation curves for
E. coli
from water and soil indicated that the sampling efforts in the Manoa watershed could not exhaust the overall genotypic diversity. Comparisons of
E. coli
genotypes from other watersheds on Oahu, Hawaii, identified no apparent grouping according to sampling locations. The results of the present study demonstrate the complexity of using
E. coli
as a fecal indicator bacterium in tropical watersheds and highlight the need to differentiate environmental sources of
E. coli
from fecal sources in water quality monitoring.
First Evidence of Genotypes Ad3a16 and Ad3a18 in North America, Obtained by Genetic Analysis of Infectious Human Adenovirus from Wastewaters of Two Urban Communities in Canada
Authors: Vidovic Sinisa , Aly Mahmoud , Flemming Cecily , Springthorpe Susan , Sattar Syed A.
Published: April 2011

A 1-year study found seven infectious human adenovirus serotypes, including Ad3, Ad31, Ad46, Ad27, Ad22, Ad51, and clinical clone PB3, in wastewaters of two major cities in Canada. Comparative genomic analysis revealed the existence of the reportedly highly contagious Ad3a16/18 genotypes. This is the first report of Ad3a16/18 genotypes in North America.
Ammonia Disinfection of Hatchery Waste for Elimination of Single-Stranded RNA Viruses
Authors: Emmoth Eva , Ottoson Jakob , Albihn Ann , Belák Sándor , Vinnerås Björn
Published: April 2011

Hatchery waste, an animal by-product of the poultry industry, needs sanitation treatment before further use as fertilizer or as a substrate in biogas or composting plants, owing to the potential presence of opportunistic pathogens, including zoonotic viruses. Effective sanitation is also important in viral epizootic outbreaks and as a routine, ensuring high hygiene standards on farms. This study examined the use of ammonia at different concentrations and temperatures to disinfect hatchery waste. Inactivation kinetics of high-pathogenic avian influenza virus H7N1 and low-pathogenic avian influenza virus H5N3, as representatives of notifiable avian viral diseases, were determined in spiked hatchery waste. Bovine parainfluenza virus type 3, feline coronavirus, and feline calicivirus were used as models for other important avian pathogens, such as Newcastle disease virus, infectious bronchitis virus, and avian hepatitis E virus. Bacteriophage MS2 was also monitored as a stable indicator. Coronavirus was the most sensitive virus, with decimal reduction (
D
) values of 1.2 and 0.63 h after addition of 0.5% (wt/wt) ammonia at 14 and 25°C, respectively. Under similar conditions, high-pathogenic avian influenza H7N1 was the most resistant, with
D
values of 3.0 and 1.4 h. MS2 was more resistant than the viruses to all treatments and proved to be a suitable indicator of viral inactivation. The results indicate that ammonia treatment of hatchery waste is efficient in inactivating enveloped and naked single-stranded RNA viruses. Based on the
D
values and confidence intervals obtained, guidelines for treatment were proposed, and one was successfully validated at full scale at a hatchery, with MS2 added to hatchery waste.
Complete Genome Sequence of a Beneficial Plant Root-Associated Bacterium, Pseudomonas brassicacearum
Authors: Ortet Philippe , Barakat Mohamed , Lalaouna David , Fochesato Sylvain , Barbe Valérie , Vacherie Benoit , Santaella Catherine , Heulin Thierry , Achouak Wafa
Published: April 2011

To shed light on the genetic equipment of the beneficial plant-associated bacterium
Pseudomonas brassicacearum
, we sequenced the whole genome of the strain NFM421. Its genome consists of one chromosome equipped with a repertoire of factors beneficial for plant growth. In addition, a complete type III secretion system and two complete type VI secretion systems were identified. We report here the first genome sequence of this species.
Distinct Physiological Roles of the Three [NiFe]-Hydrogenase Orthologs in the Hyperthermophilic Archaeon Thermococcus kodakarensis
Authors: Kanai Tamotsu , Matsuoka Ryoji , Beppu Haruki , Nakajima Akihito , Okada Yoshihiro , Atomi Haruyuki , Imanaka Tadayuki
Published: April 2011

Hydrogenases catalyze the reversible oxidation of molecular hydrogen (H
2
) and play a key role in the energy metabolism of microorganisms in anaerobic environments. The hyperthermophilic archaeon
Thermococcus kodakarensis
KOD1, which assimilates organic carbon coupled with the reduction of elemental sulfur (S
0
) or H
2
generation, harbors three gene operons encoding [NiFe]-hydrogenase orthologs, namely, Hyh, Mbh, and Mbx. In order to elucidate their functions
in vivo
, a gene disruption mutant for each [NiFe]-hydrogenase ortholog was constructed. The Hyh-deficient mutant (PHY1) grew well under both H
2
S- and H
2
-evolving conditions. H
2
S generation in PHY1 was equivalent to that of the host strain, and H
2
generation was higher in PHY1, suggesting that Hyh functions in the direction of H
2
uptake in
T. kodakarensis
under these conditions. Analyses of culture metabolites suggested that significant amounts of NADPH produced by Hyh are used for alanine production through glutamate dehydrogenase and alanine aminotransferase. On the other hand, the Mbh-deficient mutant (MHD1) showed no growth under H
2
-evolving conditions. This fact, as well as the impaired H
2
generation activity in MHD1, indicated that Mbh is mainly responsible for H
2
evolution. The copresence of Hyh and Mbh raised the possibility of intraspecies H
2
transfer (i.e., H
2
evolved by Mbh is reoxidized by Hyh) in this archaeon. In contrast, the Mbx-deficient mutant (MXD1) showed a decreased growth rate only under H
2
S-evolving conditions and exhibited a lower H
2
S generation activity, indicating the involvement of Mbx in the S
0
reduction process. This study provides important genetic evidence for understanding the physiological roles of hydrogenase orthologs in the
Thermococcales
.
Rapid Divergence of Two Classes of Haemophilus ducreyi
Authors: Ricotta Emily E. , Wang Nan , Cutler Robin , Lawrence Jeffrey G. , Humphreys Tricia L.
Published: April 2011

Haemophilus ducreyi
, the etiologic agent of chancroid, expresses variants of several key virulence factors. While previous reports suggested that
H. ducreyi
strains formed two clonal populations, the differences between, and diversity within, these populations were unclear. To assess their variability, we examined sequence diversity at 11
H. ducreyi
loci, including virulence and housekeeping genes, augmenting published data sets with PCR-amplified genes to acquire data for at least 10 strains at each locus. While sequences from all 11 loci place strains into two distinct groups, there was very little variation within each group. The difference between alleles of the two groups was variable and large at 3 loci encoding surface-exposed proteins (0.4 <

K
S

< 1.3, where

K
S

is divergence at synonymous sites) but consistently small at genes encoding cytoplasmic or periplasmic proteins (

K
S

< 0.09). The data suggest that the two classes have recently diverged, that recombination has introduced variant alleles into at least 3 distinct loci, and that these alleles have been confined to one of the two classes. In addition, recombination is evident among alleles within, but not between, classes. Rather than clones of the same species, these properties indicate that the two classes may form distinct species.
INR derivation with the PT/INR Line simplified using a spreadsheet from the world wide web
Authors: Poller Leon , Ibrahim Saied , Pattison Albert , Jespersen Jørgen ,   European Action on Anticoagulation (EAA), formerly European Concerted Action on Anticoagulation (ECAA)
Published: April 2011

Background

The prothrombin time/international normalised ratio (PT/INR) Line method to derive INR, based on only five European Concerted Action on Anticoagulation (ECAA) certified plasmas, is shown to be reliable in previous ECAA studies. A simpler method not requiring linear regression calculation would be an advantage.

Method

After determining the local PT/INR Line, local INRs have been obtained using a readily available spreadsheet on the internet which laboratories can use without performing any additional calculations.

Results

Examples of INR derivation have been obtained from results at 16 centres using a range of local coagulometers with human thromboplastin international reference preparations (IRPs). The procedure does not require manual PT testing, local international sensitivity index calibration, availability of thromboplastin IRPs or local mean normal prothrombin time.

Conclusions

From the PT/INR Line, INR values for local PT results are easily obtained using an Excel spreadsheet from our website (http://www.anticoagulants.co.uk/) which does not require the complex linear regression analysis to derive INR.
Assessing the environmental distribution of pollutants released from chemical accidents
Authors: Meharg A. A.
Published: April 2011

Case histories of the dispersal of chemicals released accidentally into the environment are reviewed with the purpose of developing strategies for assessing the ecological impact of chemical accidents. The range of accidents reported in the literature are diverse, as are the approaches used to follow up pollution events to assess ecological damage. The review classifies accidents according to the environmental components (atmospheric, aquatic, and terrestrial) that they pollute and the approaches for assessing damage to each of these components are discussed. From the literature reports of chemical accidents, it is clear that cohesive approaches must be developed for quantifying environmental contamination.Key words: Bhopal, chemical accidents and spills, environmental contamination, modelling pollution events, Seveso, Schweizerhalle.
Carnitine palmitoyltransferases in pea leaf chloroplasts: partial purification, location, and properties
Authors: Masterson Christine , Wood Clifford
Published: April 2011

Carnitine palmitoyltransferase (EC 2.3.1.21), an enzyme that catalyses the reversible transfer of activated long-chain acyl groups between CoASH and L-carnitine, has been confirmed in pea leaf chloroplasts. This enzyme is bound to the chloroplast inner envelope membrane and has two isoforms, one bound to the outside (cytosol side) of the inner envelope and one bound to the inside (stromal side) of the inner envelope. Malonyl CoA inhibited the activity of the outer carnitine palmitoyltransferase, while stimulating the activity of the inner isoform and may be a regulator of these enzymes in vivo. Carnitine palmitoyltransferase was solubilized from the chloroplast envelope by detergent treatment and the two isoforms separated by Q-Sepharose anion exchange chromatography. Both proteins were immunochemically observed by probing Western blots of sodium dodecyl sulfate - polyacrylamide gel electrophoresis gels using an anti-beef heart mitochondrial carnitine palmitoyltransferase polyclonal antibody. The monomeric molecular mass of the protein recognized by this antibody was approximately 20 kDa. This 20-kDa protein also bound3H-carnitine. Both isoforms had broad acyl CoA substrate specificities, but showed increased activity with desaturated long-chain acyl CoAs, exhibiting a preference for linolenoyl CoA. A role for carnitine palmitoyltransferase in the shuttling of fatty acids across the chloroplast envelope is suggested.Key words: Pisum sativum, chloroplasts, carnitine palmitoyltransferase, fatty acid metabolism, eukaryotic pathway, membrane transport.
Analyse des composantes de la croissance en hauteur et de la formation du tronc chez le chêne sessile, Quercus petraea (Matt.) Liebl. (Fagaceae) en sylviculture dynamique
Authors: Heuret P , Barthélémy D , Nicolini E , Atger C
Published: April 2011

Simultaneous observation of morphological and anatomical markers allowed us to reconstitute the growth pattern of the main axis in two populations of sessile oak aged 15 and 29 years, respectively. The comparison of the morphological features of annual shoots and growth units according to either their ontogenic age or their year of formation allowed us to separate endogenous trends in the development of the tree and variations resulting from the effect of annual growth conditions. Three stages of tree development were identified. The first stage is characterized by the regular production of monocyclic annual shoots with a stable mean length and is typical of young trees growing under a dense canopy. In the second stage of development, the intrinsic growth pattern expresses itself dominantly; this stage is marked by a systematic increase in the length and polycyclism rate of successive annual shoots, and by a strong differentiation between the successive growth units of polycyclic annual shoots. In the third stage, environmental factors have a stronger influence on the ontogenic growth pattern. In this stage, the length of the different growth units and annual shoots is stationary but shows important annual variations, while the differentiation between the successive growth units of bicyclic annual shoots is not systematic.Key words: Quercus petraea, sessile oak, morphology, primary growth, ontogeny.
Seed flora of La Pérouse Bay, Manitoba, Canada: a DELTA database of morphological and ecological characters
Authors: Chang E R , Dickinson T A , Jefferies R L
Published: April 2011

An identification database for seeds in coastal habitats at La Pérouse Bay, Manitoba, Canada, was developed using the DELTA (DEscriptive Language for Taxonomy) format and the program INTKEY. The database should be applicable throughout the coastal lowlands of the Hudson Bay and James Bay regions as similar plant assemblages are present. The database, based upon morphological characteristics and also incorporating ecological information, was used to identify seed specimens found in soil cores and seed traps. The most useful characters for identifying seeds were seed length, seed width, and seed shape. The database is available on the World Wide Web at http://prod.library.utoronto.ca/polyclave/. The seed flora is also documented in the form of a checklist, the first one published for the La Pérouse Bay region; this checklist is also applicable to other coastal areas in the Hudson Bay lowlands.Key words: Arctic, DELTA, floristics, identification, seed morphology.
Enhanced water relations of residual foliage following defoliation in Populus tremuloides
Authors: Hart Miranda , Hogg E H , Lieffers V J
Published: April 2011

Stomatal conductance and leaf water potential of aspen (Populus tremuloides Michx.) were measured in response to defoliation intensity, both in the field and under controlled conditions. There was evidence of increased stomatal conductance in trees with 50 and 98% defoliation, but no change in leaf water potential. Under controlled conditions, stomatal conductance and rate of photosynthesis were measured under high and low vapour pressure deficits (VPD). Under high VPD, overall stomatal conductance and rates of photosynthesis were greatly reduced. However, in both VPD treatments, there was evidence of increased stomatal conductance and compensatory photosynthesis following defoliation. These findings may be due to increases in leaf specific hydraulic conductance following defoliation.Key words: defoliation, stomatal conductance, leaf water potential, compensatory photosynthesis.
Acidity of and the concentrations of major and minor metals in the surface waters of bryophyte assemblages from 20 North American bogs and fens
Authors: Mullen Steven F , Janssens Jan A , Gorham Eville
Published: April 2011

One hundred and thirty-five samples of surface water, associated with bryophyte plots distributed across 20 wetlands in Newfoundland, Nova Scotia, Ontario, Alaska, Maine, Minnesota, and New York, were analyzed for pH and 11 elements, several of them seldom measured in wetlands. The overall order of elemental abundance was the following: Ca, Si, Na, Mg, Fe, K, Al, Mn, Sr, Ba, and Ti. Principal-components analysis of the pH and elemental chemistries of the water samples revealed seven subcategories that could be recognized as belonging to maritime and continental ombrotrophic bogs and poor, rich, and calcareous rich fens. The primary axis related to pH and the concentrations of alkaline earths, as well as to Si. The secondary axis segregated an unusual group of Alaskan fens; it was related mainly to Fe and Mn, and to a lesser degree Al and K. The tertiary axis separated maritime from continental bogs and was related chiefly to Na. The distribution of bryophyte species, most of them widespread in bogs and fens elsewhere, was most clearly related to pH and Ca concentration. As expected, many species exhibited narrow ranges of these chemical properties, whereas many others were widely distributed.Key words: mosses, peatlands, species diversity, water chemistry.
The use of RAPD markers to distinguish among juniper and cedar cultivars
Authors: Hsiang Tom , Huang Junbin
Published: April 2011

Two species of Chamaecyparis and six cultivars each of Juniperus chinensis L. and Juniperus scopulorum Sarg. (Cupressaceae) were subjected to random amplified polymorphic DNA (RAPD) analysis using seven primers. Unweighted pair group method with averages (UPGMA) and principal component analyses of genetic distances between cultivars showed that 42 polymorphic RAPD bands could distinguish among all cultivars and properly group them by species and genera. Where the origin of a specific juniper cultivar is uncertain, analysis of genetic distance can pinpoint close relatives. For example, we were unable to trace the origin of J. chinensis 'Alps', and we initially thought it was a mislabeled J. chinensis 'Blue Alps'. However, we found 'Alps' to be closer to J. chinensis 'Fairview' and 'Mountbatten' than to 'Blue Alps'. Similarly, 'Wichita Blue' has an unknown origin, but it had the highest genetic similarity with 'Medora'.Key words: juniper, cedar, RAPD, cultivars, phylogenetics.
Compensatory growth of three herbaceous perennial species: the effects of clipping and nutrient availability
Authors: Hicks Samantha , Turkington Roy
Published: April 2011

The continuum of responses model (CRM) and the growth rate model (GRM) make conflicting predictions about the effects of soil nutrient availability on the resilience of plants to herbivory. A factorial experiment was conducted in the understory of the boreal forest to examine the effects of fertilization and simulated herbivory on the rate and amount of regrowth of three herbaceous perennial species (Achillea millefolium L., Festuca altaica Trin., and Mertensia paniculata (Aiton) G. Don.). As clipping intensity increases various measures of plant performance decrease. Fertilization reduces the ability of clipped plants to compensate for biomass loss regardless of species and growth measure. Under natural soil fertility levels in this study, M. paniculata is more likely to compensate for leaf loss than A. millefolium and F. altaica. Contrary to the findings of previous field studies, the compensatory responses of the three species studied were most consistent with the predictions of the GRM. Plants in our study sites grow in nutrient-poor soils, whereas the majority of compensatory studies have been carried out on herbaceous or woody plants in temperate regions. Resources are generally more abundant in temperate zones than in boreal forest zones, and the GRM may be a better predictor of compensatory ability of plants growing in naturally nutrient-deficient soils.Key words: herbivory, regrowth, fertility level, clipping intensity, compensation.
Polyclonal antisera to epacrid mycorrhizae and to Hymenoscyphus ericae display specificity
Authors: Parry R A , McLean C B , Alderton M R , Coloe P J , Lawrie A C
Published: April 2011

Three polyclonal antisera produced in mice were used to investigate specificity and cross-reactivity between ericaceous and epacridaceous mycorrhizal fungi. One antiserum was to a culture of Hymenoscyphus ericae (Read) Korf and Kernan, the fungal endophyte of Calluna vulgaris (L.) Hull (Ericaceae). The other two were to peloton preparations from roots of Epacris impressa Labill. (Epacridaceae) from two sites (Cranbourne and Grampians) in Victoria, Australia. By immunofluorescence, all three antisera recognised H. ericae but not Oidiodendron griseum Roback, suggesting a serological relationship with the former endophyte. They also recognised 10 of the 12 fungal isolates tested, from mycorrhizal roots of E. impressa (Cranbourne), and all 4 isolates from Astroloma pinifolium (R. Br.) Benth. (Epacridaceae) (Grampians). Furthermore, none of the antisera recognised any of the nine common soil-inhabiting fungi selected for screening. Antisera recognised only unmelanized hyphae on epacrid and other plant roots taken from the wild. With plants from Cranbourne, all antisera except the Grampians antiserum recognised hyphae only on epacrid roots, demonstrating specificity. Hyphae on other plant roots were not recognised by any of the antisera. With plants from the Grampians, all antisera recognised some hyphae on both epacrid and other plant roots, except in two instances. The immunogold labelling indicates that the antisera are specific for fungi and do not recognise the plant. Since the fungal isolate forms true mycorrhizal structures, this suggests that there is a serological similarity between fungi forming epacrid mycorrhiza and those (H. ericae) forming ericoid mycorrhiza.Key words: ericoid mycorrhizae, Epacridaceae, polyclonal antibodies, immunofluorescence, immunogold.
Nutrient resorption in Claytonia virginica L.: implications for deciduous forest nutrient cycling
Authors: Anderson Wendy B , Eickmeier William G
Published: April 2011

According to the vernal dam hypothesis, spring ephemeral herbs temporarily sequester large nutrient pools in deciduous forests prior to canopy closure and return the nutrients to the soil following senescence of aboveground tissues. However, many species resorb nutrients from their leaves back to belowground tissues during senescence, and the degree of resorption is often associated with soil nutrient availability. Species that store large proportions of their absorbed nutrients between years are not participating in the temporary sequestering and rapid recycling of nutrients implied by the vernal dam. We investigated the extent to which Claytonia virginica L. sequestered and returned nutrients to the soil in response to nitrogen (N) and phosphorus (P) availability. We tested the effect of nutrient availability on nutrient use efficiency, resorption efficiency, and resorption proficiency (% nutrient in senescent leaves) of Claytonia. Nutrient additions significantly decreased N but not P use efficiency of Claytonia, particularly as the growing season progressed. Nutrient additions also significantly reduced N resorption efficiency from 80 to 47% and decreased P resorption efficiency from 86 to 56%. N and P resorption proficiencies were also significantly lower in senesced leaves of fertilized plants: N concentrations were 2.33% when unfertilized and 4.13% when fertilized, while P concentrations were 0.43% when unfertilized versus 0.57% when fertilized. When unfertilized, Claytonia was more efficient at resorption compared with other spring herbs, but similar to other species when fertilized. However, Claytonia was much less proficient in resorbing nutrients than other reported plants, because senescent tissues maintained substantially higher concentrations of N and P, particularly when fertilized. In conclusion, Claytonia, an important spring ephemeral species, exhibits physiological responses that emphasize its role in the vernal dam by its temporary sequestration and substantial, rapid return of nutrients in deciduous forests. Adding nutrients to the site increases the total mass and the relative proportion of nutrients that Claytonia returns to the soil rather than sequestering between seasons, which ultimately increases nutrient recycling rates within the entire system.Key words: Claytonia virginica, nutrient response, resorption efficiency, nutrient cycling, spring ephemerals, vernal dam.
Paleolimnological analyses of cultural eutrophication patterns in British Columbia lakes
Authors: Reavie Euan D , Smol John P , Sharpe Ian D , Westenhofer Lisa A , Roberts Anne-Marie
Published: April 2011

Diatom-based paleolimnological approaches were used to determine the effects of cultural impacts on eutrophication histories in four lakes from central British Columbia. Stratigraphic analysis of fossil diatoms in 210Pb-dated cores and inferences of past total phosphorus concentrations using diatom-based models were used to reconstruct the nutrient histories of Takysie, Tchesinkut, Francois, and Tyhee lakes. Diatom microfossils indicate that these lakes are probably naturally productive, but some nutrient enrichment has likely occurred in response to human development (since A.D. 1850), particularly in Tyhee Lake. However, in Tchesinkut and Francois lakes, some reduction in total phosphorus may have occurred in recent decades. Takysie, Tchesinkut, and Francois lakes have been dominated by planktonic diatoms indicative of high productivity (e.g., Stephanodiscus, Asterionella, Fragilaria crotonensis, Aulacoseira). Tyhee Lake has been dominated by benthic Fragilaria species, but Stephanodiscus minutulus has increased in recent decades. These data were pooled with previously published paleolimnological data from British Columbia to summarize cultural eutrophication patterns in this region. Out of 11 British Columbia lakes considered, 10 were productive before human intervention, but 7 eutrophied further as a result of human activities. One lake exhibited no obvious post-1850 change in diatom assemblage, suggesting little human impact on water quality. In three of the lakes, recent improvements in water quality may have occurred in response to recent mitigation efforts.Key words: eutrophication, paleolimnology, British Columbia, diatoms, lakes, mining.
Cell wall differentiation during early somatic embryogenesis in plants. I. Scanning and transmission electron microscopy study on embryos originating from direct, indirect, and adventitious pathways
Authors: Chapman Audrey , Blervacq Anne-Sophie , Tissier Jean-Pierre , Delbreil Bruno , Vasseur Jacques , Hilbert Jean-Louis
Published: April 2011

In three modes of somatic embryogenesis, direct (Cichorium), indirect (Citrus), and adventitious (Asparagus), a layer enveloped the proembryo and separated it from parenchyma or callus cells. This layer was either torn or partly dissolved during embryo expansion and led to a reticulated fibrillar structure linking the peripheral cells of the embryo prior to protoderm differentiation. Scanning electron microscopic and transmission electron microscopic analyses revealed it as a net-like structure composed of thick fibres restricted to the embryo surface during a specific developmental stage. Stereo pairs of micrographs revealed its two-dimensional arrangement. The spatio-temporal localization of this fibrillar network defined it as an intermediate stage of somatic embryogenesis in monocotyledonous and dicotyledonous species irrespective of their modes of development. Hypotheses concerning the origin of the fibrillar network are provided, and its possible functions during somatic embryogenesis are discussed.Key words: Asparagus officinalis L. (asparagus), cell wall, Cichorium (chicory), Citrus (Troyer citrange), somatic embryogenesis.
Preformation, neoformation, and shoot structure in Nothofagus dombeyi (Nothofagaceae)
Authors: Puntieri Javier G , Souza María S , Barthélémy Daniel , Brion Cecilia , Nuñez Martín , Mazzini Camilo
Published: April 2011

Buds in different positions along trunk, main branch, secondary branch, and short branch parent shoots of young Nothofagus dombeyi (Mirb.) Blume trees were dissected, and the number of organs of their rudimentary shoots was counted. Bud contents were compared with the number of organs of sibling shoots developed in positions equivalent to those of the dissected buds. Cataphyll number was relatively constant for all buds. The number of green leaf primordia differentiated in each bud depended both on the position of the bud on the parent shoot and on the size of the parent shoot. Sibling shoots derived distally from large parent shoots had more nodes than the rudimentary shoots of buds in a similar position. Proximal sibling shoots derived from large parent shoots and all sibling shoots derived from small parent shoots are entirely preformed. In N. dombeyi, the size gradient of the sibling shoots derived from a particular parent shoot relates mostly to variation in organ preformation, organ neoformation, and internode extension. The expression of each of these sources of variation is related to the position of the sibling shoot on the parent shoot and on the position of the parent shoot on the tree. Consideration is given to the role of environmental conditions on tree development, in view of the species' morphogenetic gradientsKey words: branching, bud content, sylleptic branching, leaf primordia, Nothofagus, preformation.
Réponses fonctionnelles des communautés de pelouses calcicoles aux facteurs agro-écologiques dans les Préalpes françaises
Authors: Barbaro Luc , Corcket Emmanuel , Dutoit Thierry , Peltier Jean-Paul
Published: April 2011

The identification of functional groups in calcareous grasslands of southern Vercors (Rhône-Alpes, France) is investigated through relationships between biological traits of the species and agro-ecological factors. Community patterns are determined by (i) the level of edaphic stress (oligotrophy and xericity) and (ii) the regime and the intensity of agropastoral management (grazing and mechanical cutting). In such grasslands submitted to regular disturbance, life traits related to dispersal and regeneration processes have greater importance for the differentiation of species than morphological traits, and Grime's adaptative strategies are the best predictors of species ordination on agro-ecological gradients (e.g., stress and disturbance). A classification of species in functional groups based on the same life traits and similar responses to disturbances is proposed, and its role in defining adequate conservation management of calcareous grassland by low-intensity livestock farming is discussed. The functional role of grazing is emphasized by the relationship between species dominance or rarity and their levels of consumption and dispersion by sheeps. In calcareous grassland communities, dominant species are the most palatable and the most dispersed by sheeps, while rarer species depend on other dispersal modes, such as seed rain or mowing machinery.Key words: life traits, functional groups, agropastoral practices, conservation management, RLQ analysis.
The ultrastructure of the dimorphic infection cells of Haptoglossa heteromorpha illustrates the developmental plasticity of infection apparatus structures in a nematode parasite
Authors: Glockling Sally L , Beakes Gordon W
Published: April 2011

The nematophagous fungus Haptoglossa heteromorpha Glockling & Beakes is unusual in this genus, as it consistently produces two morphologically distinct infection cells that develop respectively from the large and small aplanospores. The large infection cells are typical "gun cells" and are uninucleate with over half the cytoplasmic volume occupied by the basal vacuole. However, the small infection cells are considerably modified in their structure. They have an elongate tapered morphology with a bilobed base. Small infection cells are binucleate and contain both apical and basal vacuolar regions. The inverted injection tube is highly modified and originates at a raised padlike region on the mid ventral side of the cell. This protruding pad is associated with a diffuse covering of fibrillar material. The bore region extends deep into the cell and the highly compressed missile chamber is located beneath the hindmost nucleus, near the base of the cell. Finally, there is a more typical tube tail segment, which winds between the nuclei and eventually terminates beneath the anterior vacuole. The differences with gun cells of previously described Haptoglossa species are documented. The functional and biological significance of these two different infection cells is discussed. Only the large gun cells were observed to discharge to form sporidia. It seems unlikely that the highly modified smaller cells can infect in this way. It may be that the two different cell types have evolved to infect different hosts, but no direct confirmation of this could be obtained.Key words: Haptoglossa, host-parasite interactions, infection (gun) cell, nematophagous fungi, ultrastructure.
Isolation and characterization of mutants of the citrus canker pathogen Xanthomonas axonopodis pv. citri that induce a distinct pattern of disease
Authors: Tung Shu Yun , Kuo Tsong Teh
Published: April 2011

Random mutagenesis with the transposon Tn5tac1 in Xanthomonas axonopodis pathovar citri, the causal agent of citrus canker, generated four mutants with altered pathogenicity. These mutants were classified into three groups: (i) the nonpathogenic (NP) mutants XT10 and XT122, which did not induce any visible symptoms in the host; (ii) the WS- mutant XT27, which induced a callus-like lesion but not a watersoaked lesion; and (iii) the CL- mutant XT37, which was unable to induce a callus-like eruption but did induce the formation of a watersoaked lesion around the infection site. The NP mutants failed to grow in planta, whereas the WS- and CL- mutants showed a reduced growth rate relative to that of the wild type. Co-inoculation of leaves with the WS- and CL- mutants did not result in complementation of their respective defects. The extent of extracellular accumulation of polysaccharide, protease, and amylase activities by each of the mutants was similar to that of the wild type. The extracellular activity of polygalacturonate lyase of XT27 was reduced relative to that of the wild type and other mutants. Unlike the wild type and other mutants, XT27 also required glutamic acid for growth in culture. Southern blot hybridization revealed that each of the mutants resulted from transposon insertion at a single site; the insertion sites for XT10 and XT27 were located in the chromosome, whereas those for XT37 and XT122 were located in the indigenous plasmids. These results provide evidence that bacterial genes contribute independently to the pathogenesis of citrus canker.Key words: citrus canker, pathogenicity genes, transposon mutagenesis.