bluuebunny/crossref_metadata_2025 huggingface dataset:
Analytical intercomparison between flow injection‐chemiluminescence and flow injection‐spectrophotometry for the determination of picomolar concentrations of iron in seawater
Authors: Bowie Andrew R. , Sedwick Peter N. , Worsfold Paul J.
Published: April 2011

A lab‐ and ship‐based analytical intercomparison of two flow injection methods for the determination of iron in seawater was conducted, using three different sets of seawater samples collected from the Southern Ocean and South Atlantic. In one exercise, iron was determined in three different size‐fractions (<0.03 µm, <0.4 µm, and unfiltered) in an effort to better characterize the operational nature of each analytical technique with respect to filter size. Measured Fe concentrations were in the range 0.19 to 1.19 nM using flow injection with luminol chemiluminescence detection (FI‐CL), and 0.07 to 1.54 nM using flow injection with catalytic spectrophotometric detection with N,N‐dimethyl‐p‐phenylenediamine dihydrochloride (FI‐DPD). The arithmetic mean for the FI‐CL method was higher (by 0.09 nM) than the FI‐DPD method for dissolved (<0.4 µm) Fe, a difference that is comparable to the analytical blanks, which were as high as 0.13 nM (CL) and 0.09 nM (DPD). There was generally good agreement between the FI‐CL determinations for the <0.03 µm size fraction and the FI‐DPD determinations for the <0.4 µm size fraction in freshly collected samples. Differences in total‐dissolvable (unfiltered) Fe concentrations determined by the two FI methods were more variable, reflecting the added complexity associated with the analysis of partially digested particulate material in these samples. Overall, however, the FI‐CL determinations were significantly (P = 0.05) lower than the FI‐DPD determinations for the unfiltered samples. Our results suggest that the observed, systematic inter‐method differences reflect measurement of different physicochemical fractions of Fe present in seawater, such that colloidal and/or organic iron species are better determined by the FI‐CL method than the FI‐DPD method. This idea is supported by our observation that inter‐method differences were largest for freshly collected acidified seawater, which suggests extended storage (>6 months) of acidified samples as a possible protocol for the determination of dissolved iron in seawater.
Estimates of bacterial production using the leucine incorporation method are influenced by differences in protein retention of microcentrifuge tubes
Authors: Pace Michael L. , del Giorgio Paul , Fischer David , Condon Robert , Malcom Heather
Published: April 2011

The most widely used methods to determine bacterial production involve measuring the incorporation of radioactive precursors, such as leucine, into macromolecular pools. The leucine method that involves incubation and extraction within a single microcentrifuge tube has become a widely used technique because of its relative convenience, precision, and low cost. We observed a discrepancy in parallel determinations of leucine incorporation for the same water samples that lead us to explore aspects of the method including tube‐washing methods, operator differences, and differences among tube brands. Operators and washing methods had minimal effects on rate measurements, but results were strongly dependent on tube brands. Differences in tube performance were observed consistently in comparisons from a variety of freshwater and marine environments. Microcentrifuge tubes differed in protein retention with the consequence that estimates of leucine incorporation in a given sample could vary by as much as 60% depending on the tube used. There was no simple relationship between tube plastics or manufacturer and tube performance. We advise researchers to check the protein retention of tubes and to use the same brand of tube during field studies to minimize this potential source of variation.
Hydrolysis‐induced racemization of amino acids
Authors: Kaiser Karl , Benner Ronald
Published: April 2011

Acid hydrolysis—induced racemization compromises accurate determination of enantiomeric amino acid compositions. In the present study, the extent of amino acid racemization during a vapor (6 M HCl, 32.5 min, 150±C) and liquid‐phase hydrolysis (6 M HCl, 20 h, 110±C) was assessed, and the influence on the accuracy of enantiomer measurements was investigated. The extent of hydrolysis‐induced racemization was controlled by the molecular structure of the amino acid polymer and hydrolysis conditions. Vapor‐phase hydrolysis showed significantly higher racemization compared to liquid‐phase hydrolysis. Without correction, hydrolysis‐induced racemization resulted in overestimation of D‐enantiomers and could lead to erroneous conclusions about the occurrence of D‐enantiomers in natural samples. The range of racemization was determined with proteins and free amino acids, and an averaged racemization value is proposed to account for enantiomer exchange during hydrolysis. In addition, a microwave‐assisted vapor‐phase hydrolysis is described that allows preparation of 40 samples in about 3 h with very low blanks.
Improved quantitative real‐time PCR assays for enumeration of harmful algal species in field samples using an exogenous DNA reference standard
Authors: Coyne Kathryn J. , Handy Sara M. , Demir Elif , Whereat Edward B. , Hutchins David A. , Portune Kevin J. , Doblin Martina A. , Cary S. Craig
Published: April 2011

Quantitative real‐time PCR (QPCR) is a powerful and sensitive method for quantitative detection of microorganisms. Application of this methodology for enumeration of harmful algal bloom (HAB) species has the potential to revolutionize our approach to HAB research, making it possible to identify correlations between cell abundances and factors that regulate bloom dynamics. Its application to ecological studies, however, has produced mixed results. QPCR assays typically rely on the generation of standard curves from plasmids or laboratory cultures that may be unrealistic when compared to amplification of DNA extracted from field samples. In addition, existing methods often fail to incorporate controls to assess variability in extraction and amplification efficiencies, or include controls that are sequence‐specific and preclude the investigation of multiple species. Here, we describe the development and rigorous analysis of QPCR assays for two HAB species, Chattonella subsalsa and Heterosigma akashiwo, in which we introduce a known concentration of exogenous DNA plasmid into the extraction buffer as a reference standard. Since the target DNA is extracted in the presence of the reference standard, inherent variability in extraction and amplification efficiencies affect both target and standard equally. Furthermore, the reference standard is applicable to QPCR analysis of any microbial species. Using environmental bloom samples as calibrators, we evaluated the accuracy of the comparative Ct method for enumeration of target species in several field samples. Our investigation demonstrates that the comparative Ct method with an exogenous DNA reference standard provides both accurate and reproducible quantification of HAB species in environmental samples.
Isolation, amplification, and identification of ancient copepod DNA from lake sediments
Authors: Bissett Andrew , Gibson John A. E. , Jarman Simon N. , Swadling Kerrie M. , Cromer Louise
Published: April 2011

Species identification of copepods in lake sediments is often difficult because their remains lack diagnostic features. It is therefore not easy to track changes in copepod biodiversity in lakes through time. We report a method for the isolation, amplification, and identification of copepod DNA from whole lake sediments formed in the early Holocene to the present. The method, which involves amplification of a short (~300 base pair) DNA sequence that varies between copepod species, provides a new approach to the study of copepod paleobiodiversity. Successful amplification of copepod DNA was possible in samples as old as 9950 calibrated 14C y BP. Attempts failed to recover DNA from a sediment sample ca 65,000 years old. In most cases the species identified in the sediments matched those of extant lake populations, but analysis of early‐mid Holocene sediments from one lake revealed a species that is not present today. We were able to recover copepod DNA from core samples stored at −20° C, at 4° C, and preserved with polyethyleneglycol.
Environmental triggers of multiple sclerosis
Authors: Kakalacheva Kristina , Lünemann Jan D.
Published: April 2011

Multiple sclerosis is a chronic immune‐mediated disease of the central nervous system that develops in young adults with a complex genetic predisposition. Similar to other autoimmune disease, HLA‐DR and ‐DQ alleles within the HLA class II region on chromosome 6p21 are by far the strongest risk‐conferring genes. Less robust susceptibility effects have been reported for non‐MHC related genetic variants. Improvements in the design of epidemiological studies helped to identify consistent environmental risk‐associations such as the increased susceptibility for MS in individuals with a history of infectious mononucleosis, a symptomatic primary infection with the human γ‐herpesvirus Epstein–Barr virus (EBV). Sun exposure and serum vitamin D levels are emerging non‐infectious environmental risk factors that may have independent roles. The analysis of environmental effects will likely expand in the next few years and will allow for the generation of testable hypotheses as to how environmental insults interact with genetic factors to jointly determine the susceptibility to MS. Insights gained from these studies might facilitate the development of prevention strategies and more effective treatments for MS.
Loktanella tamlensis sp. nov., isolated from seawater
Authors: Lee Soon Dong
Published: April 2011

An aerobic, Gram-reaction-negative, chemo-organotrophic bacterium, designated strain SSW-35T, was isolated from seawater in Jeju, Republic of Korea. Cells were motile, short rods; colonies were circular, smooth, convex, translucent and beige in colour. No diffusible pigment formed on any of the media tested. The bacterium grew at 4–30 °C and pH 7.1–10.1. Phylogenetic analysis based on 16S rRNA gene sequences showed that the organism was related to members of the genus Loktanella, its closest recognized relatives being Loktanella rosea Fg36T (98.1 % sequence similarity) and Loktanella maricola DSW-18T (97.8 %). Levels of 16S rRNA gene similarity between strain SSW-35T and other recognized species of the genus Loktanella were all <97 %. Polar lipid analysis revealed the presence of diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol and an unknown lipid as major components, as well as small amounts of two unknown phospholipids. The predominant ubiquinone was Q-10. The major cellular fatty acid was C18 : 1 (summed feature 7), and the 3-hydroxy fatty acids detected were C12 : 1 3-OH and C10 : 0 3-OH. The genomic DNA G+C content was 55.0 mol%. In DNA–DNA hybridization experiments, the relatedness values between strain SSW-35T and the type strains of the phylogenetically closest recognized species were all <11 %. On the basis of the phenotypic and genotypic characteristics, phylogenetic analysis and DNA–DNA relatedness, a novel species, Loktanella tamlensis sp. nov., is proposed. The type strain is SSW-35T ( = KCTC 12722T = JCM 14020T).
Algoriphagus namhaensis sp. nov., isolated from seawater
Authors: Oh Ki-Hoon , Kang So-Jung , Lee Soo-Young , Park Sooyeon , Oh Tae-Kwang , Yoon Jung-Hoon
Published: April 2011

A Gram-staining-negative, non-motile, non-spore-forming bacterial strain, DPG-3T, was isolated from seawater from the South Sea in Korea, and its taxonomic position was investigated using a polyphasic approach. Strain DPG-3T grew optimally at 30 °C and in the presence of 2 % (w/v) NaCl. In a neighbour-joining phylogenetic tree based on 16S rRNA gene sequences, strain DPG-3T fell within a clade comprising Algoriphagus species and appeared most closely related to Algoriphagus halophilus JC 2051T (96.1 %16S rRNA gene sequence similarity) and Algoriphagus lutimaris S1-3T (96.4 %). The type strains of other Algoriphagus species showed 16S rRNA gene sequence similarities of 92.9–96.0 % with strain DPG-3T. The predominant menaquinone of strain DPG-3T was MK-7. The major fatty acids were iso-C15 : 0 and iso-C15 : 0 2-OH and/or C16 : 1ω7c (summed feature 3). The major polar lipids detected in strain DPG-3T were phosphatidylcholine, phosphatidylethanolamine and an unidentified lipid. The genomic DNA G+C content was 44.8 mol%. On the basis of phenotypic, chemotaxonomic and phylogenetic data, strain DPG-3T is considered to represent a novel species of the genus Algoriphagus, for which the name Algoriphagus namhaensis sp. nov. is proposed. The type strain is DPG-3T ( = KCTC 23419T = CCUG 60523T).
Trypanosoma culicavium sp. nov., an avian trypanosome transmitted by Culex mosquitoes
Authors: Votýpka Jan , Szabová Jana , Rádrová Jana , Zídková Lenka , Svobodová Milena
Published: April 2011

A novel avian trypanosome, Trypanosoma culicavium sp. nov., isolated from Culex mosquitoes, is described on the basis of naturally and experimentally infected vectors and bird hosts, localization in the vector, morphological characters and molecular data. This study provides the first comprehensive description of a trypanosome species transmitted by mosquitoes, in which parasites form plugs and rosettes on the stomodeal valve. Trypanosomes occurred as long epimastigotes and short trypomastigotes in vectors and culture and as long trypomastigotes in birds. Transmission of parasites to bird hosts was achieved exclusively by ingestion of experimentally infected Culex mosquito females by canaries (Serinus canaria), but not by Japanese quails (Coturnix japonica), nor by the bite of infected vectors, nor by ingestion of parasites from laboratory cultures. Transmission experiments and the identity of isolates from collared flycatchers (Ficedula albicollis) and Culex mosquitoes suggests that the natural hosts of T. culicavium are insectivorous songbirds (Passeriformes). Phylogenetic analyses of small-subunit rRNA and glycosomal glyceraldehyde-3-phosphate dehydrogenase gene sequences demonstrated that T. culicavium sp. nov. is more related to Trypanosoma corvi than to other avian trypanosomes (e.g. Trypanosoma avium and Trypanosoma bennetti).
Oxidative stress is associated with migraine and migraine‐related metabolic risk in females
Authors: Bernecker C. , Ragginer C. , Fauler G. , Horejsi R. , Möller R. , Zelzer S. , Lechner A. , Wallner‐Blazek M. , Weiss S. , Fazekas F. , Bahadori B. , Truschnig‐Wilders M. , Gruber H.‐J.
Published: April 2011

Background and purpose:  Oxidative stress is discussed to be implicated in the pathophysiology of migraine. However, data are in part controversial and the possible underlying mechanisms remain elusive to date. The aim of this study was to investigate the oxidative stress status of female patients with migraine and its implications on migraine‐related metabolic alterations.

Methods:  Oxidative stress markers malondialdehyde (MDA), 4‐hydroxy‐2‐nonenal (HNE), carbonylated proteins, parameters of associated nitric oxide stress, inflammation, lipid‐ and glucose‐metabolism were determined in the interictal phase in female patients with migraine and controls.

Results:  We found significantly increased HNE levels in female migraineurs compared with controls. Logistic regression analyses of HNE revealed an odds ratio for migraine of 4.55. HNE showed significant correlations with the nitric oxide pathway, the insulin‐ and the lipid‐metabolism.

Conclusions:  We show here that increased oxidative stress is associated with migraine and contributes to migraine‐related metabolic risk like nitrosative stress, an atherogenic lipid profile and hyperinsulinemia. Our data suggest that oxidative stress may represent a key event in the pathophysiology of migraine and a suitable therapeutic target.
Hypo‐osmotic swelling modifies glutamate‐glutamine cycle in the cerebral cortex and in astrocyte cultures
Authors: Hyzinski‐García María C. , Vincent Melanie Y. , Haskew‐Layton Renée E. , Dohare Preeti , Keller, Jr. Richard W. , Mongin Alexander A.
Published: April 2011

J. Neurochem. (2011) 10.1111/j.1471‐4159.2011.07289.x

In our previous work, we found that perfusion of the rat cerebral cortex with hypo‐osmotic medium triggers massive release of the excitatory amino acid L‐glutamate but decreases extracellular levels of L‐glutamine (R. E. Haskew‐Layton et al., PLoS ONE, 3: e3543). The release of glutamate was linked to activation of volume‐regulated anion channels, whereas mechanism(s) responsible for alterations in extracellular glutamine remained unclear. When mannitol was added to the hypo‐osmotic medium to reverse reductions in osmolarity, changes in microdialysate levels of glutamine were prevented, indicating an involvement of cellular swelling. As the main source of brain glutamine is astrocytic synthesis and export, we explored the impact of hypo‐osmotic medium on glutamine synthesis and transport in rat primary astrocyte cultures. In astrocytes, a 40% reduction in medium osmolarity moderately stimulated the release of L‐[3H]glutamine by ∼twofold and produced no changes in L‐[3H]glutamine uptake. In comparison, hypo‐osmotic medium stimulated the release of glutamate (traced with D‐[3H]aspartate) by more than 20‐fold. In whole‐cell enzymatic assays, we discovered that hypo‐osmotic medium caused a 20% inhibition of astrocytic conversion of L‐[3H]glutamate into L‐[3H]glutamine by glutamine synthetase. Using an HPLC assay, we further found a 35% reduction in intracellular levels of endogenous glutamine. Overall, our findings suggest that cellular swelling (i) inhibits astrocytic glutamine synthetase activity, and (ii) reduces substrate availability for this enzyme because of the activation of volume‐regulated anion channels. These combined effects likely lead to reductions in astrocytic glutamine export in vivo and may partially explain occurrence of hyperexcitability and seizures in human hyponatremia.
Purification, Modeling, and Analysis of Botulinum Neurotoxin Subtype A5 (BoNT/A5) from Clostridium botulinum Strain A661222
Authors: Jacobson Mark J. , Lin Guangyun , Tepp William , Dupuy Jerome , Stenmark Pål , Stevens Raymond C. , Johnson Eric A.
Published: April 2011

A
Clostridium botulinum
type A strain (A661222) in our culture collection was found to produce the botulinum neurotoxin subtype A5 (BoNT/A5). Its neurotoxin gene was sequenced to determine its degree of similarity to available sequences of BoNT/A5 and the well-studied BoNT/A1. Thirty-six amino acid differences were observed between BoNT/A5 and BoNT/A1, with the predominant number being located in the heavy chain. The amino acid chain of the BoNT/A from the A661222 strain was superimposed over the crystal structure of the known structure of BoNT/A1 to assess the potential significance of these differences—specifically how they would affect antibody neutralization. The BoNT/A5 neurotoxin was purified to homogeneity and evaluated for certain properties, including specific toxicity and antibody neutralization. This study reports the first purification of BoNTA5 and describes distinct differences in properties between BoNT/A5 and BoNT/A1.
Small Acid-Soluble Proteins with Intrinsic Disorder Are Required for UV Resistance in Myxococcus xanthus Spores
Authors: Dahl John L. , Fordice Daniel
Published: April 2011

Bacterial sporulation in Gram-positive bacteria results in
s
mall
a
cid-
s
oluble
p
roteins called SASPs that bind to DNA and prevent the damaging effects of UV radiation. Orthologs of
Bacillus subtilis
genes encoding SASPs can be found in many sporulating and nonsporulating bacteria, but they are noticeably absent from spore-forming, Gram-negative
Myxococcus xanthus
. This is despite the fact that
M. xanthus
can form UV-resistant spores. Here we report evidence that
M. xanthus
produces its own unique group of low-molecular-weight, acid-soluble proteins that facilitate UV resistance in spores. These
M. xanthus
-specific SASPs vary depending upon whether spore formation is induced by starvation inside cell aggregations of fruiting bodies or is induced artificially by glycerol induction. Molecular predictions indicate that
M. xanthus
SASPs may have some association with the cell walls of
M. xanthus
spores, which may signify a different mechanism of UV protection than that seen in Gram-positive spores.
Complete Genome Sequence of Lactobacillus delbrueckii subsp. bulgaricus Strain ND02
Authors: Sun Zhihong , Chen Xia , Wang Jicheng , Zhao Wenjing , Shao Yuyu , Guo Zhuang , Zhang Xingchang , Zhou Zhemin , Sun Tiansong , Wang Lei , Meng He , Zhang Heping , Chen Wei
Published: April 2011

Lactobacillus delbrueckii
subsp.
bulgaricus
strain ND02 is a Chinese commercial dairy starter used for the manufacture of yoghurt. It was isolated from naturally fermented yak milk in Qinghai, China. Here, we report the main genome features of ND02 and several differences with two other published genomes of
Lactobacillus delbrueckii
subsp.
bulgaricus
strains.
Complete Genome Sequence of the Probiotic Bacterium Lactobacillus casei LC2W
Authors: Chen Chen , Ai Lianzhong , Zhou Fangfang , Wang Lei , Zhang Hao , Chen Wei , Guo Benheng
Published: April 2011

Lactobacillus casei
LC2W, a patented probiotic strain (Z. Wu, European patent EP 1642963 B1, February 2009), has been isolated from Chinese traditional dairy products and implemented in industrial production as starter culture. Here we present the complete genome sequence of LC2W and the identification of a gene cluster implicated in the biosynthesis of exopolysaccharides.
Complete Genome Sequence of the Nitrogen-Fixing and Rhizosphere-Associated Bacterium Pseudomonas stutzeri Strain DSM4166
Authors: Yu Haiying , Yuan Menglong , Lu Wei , Yang Jian , Dai Shuxian , Li Qin , Yang Zhimin , Dong Jie , Sun Lilian , Deng Zhiping , Zhang Wei , Chen Ming , Ping Shuzhen , Han Yunlei , Zhan Yuhua , Yan Yongliang , Jin Qi , Lin Min
Published: April 2011

We present here the analysis of the whole-genome sequence of
Pseudomonas stutzeri
strain DSM4166, a diazotrophic isolate from the rhizosphere of a
Sorghum nutans
cultivar. To our knowledge, this is the second genome to be sequenced for
P. stutzeri
. The availability and analysis of the genome provide insight into the evolution of the nitrogen fixation property and identification of rhizosphere competence traits required in interactions with host plants.
The challenge of contaminated sites: remediation approaches in North America
Authors: Hrudey Steve E. , Pollard Simon J.
Published: April 2011

The pervasive occurrence of contaminated land has become a major issue facing society and involving enormous financial and social implications. Several problems arise at the interface between environmental science and public policy in dealing with future uses of such land. Contaminated sites need to have the nature and magnitude of the contamination identified. Such characterization must deal with the enormous complexity of many common wastes, the selection of appropriate analytical methods, and the heterogeneity of site conditions. Responses to these problems are limited by the capabilities of remediation technologies available. These may be categorized as containment/immobilization, mobilization, or destruction processes. In the last category, bioremediation has shown the most promise and general utility, but a number of specific requirements and constraints must be satisfied. For bioremediation to be feasible, the contaminants must be amenable to biological degradation, an appropriate and active microbial community must be provided, the contaminants must be accessible (bioavailable) to the microbial community, waste-specific constraints must be minimized, and appropriate environmental conditions must be provided for the microbial population. Cleanup criteria are fundamental to any decisions about contaminated sites. The U.S. Superfund approach has avoided developing generic contamination criteria, in contrast with the Canadian approach. Some common problems arise with either approach. There is a trend towards increasing reliance on risk assessment for site remediation decisions. Management challenges facing effective site remediation include the interdisciplinary nature of the issues, communication between laboratory and field personnel, and misrepresentation or inadequate attention to uncertainty. Constructive and positive advances to deal with these problems have been developed and include statistical sampling methods, tiered protocols, integrated toxicity testing procedures, multimedia partitioning models, and uncertainty analyses. Considering all the problems and challenges, there remains overwhelming evidence that prevention of contamination is vastly superior to remediation.Key words: waste characterization, analytical methods, cleanup technologies, bioremediation, cleanup criteria, risk management.
Chemistry of chromium in lakes
Authors: Nriagu Jerome , Beaubien Stan , Blowes David
Published: April 2011

The inputs of industrial wastes have changed the levels and forms of chromium in many lakes, and there is growing concern about the accumulation of Cr(VI), a known carcinogen, in drinking water supplies. This report provides a critical review of the effects of speciation, transformations, and solubility on the cycling of chromium in lacustrine environments. Unique features of chromium dynamics associated with the decoupling of redox-driven chromium cycle from those of iron and manganese at the sediment–water and air–water interfaces are highlighted. Reductive precipitation is important in the immobilization of pollutant chromium in sediments. Photooxidative dissolution of Cr(III) especially at the air–water interface is identified as a key area for further research. The available database is inadequate for establishing any linkages between the chromium and biological cycles in lakes.Key words: chromium, lakes, cycling, speciation, redox, geochemistry.
Trace element availability to plants in agricultural soils, with special emphasis on fertilizer inputs
Authors: Singh Bal Ram
Published: April 2011

Fertilizers, along with atmospheric deposition, are believed to contribute more than all other factors to the trace element burden of cultivated soils. This review will discuss trace elements in commercial fertilizer in relation to their transfer to soil–plant systems. Also, background levels in soils and the concentrations of trace elements in soils, phosphate rocks, and commercial fertilizers will be presented. Results from several short and long-term experiments indicated that the application of phosphate fertilizers to agricultural soils generally resulted in an increase of trace elements in soils and that the increase was most pronounced for Cd. The corresponding increase in plants was quite variable, ranging from no increase at all to a significant increase. The concentration of trace elements in plant species also showed a wide variation. The distribution and partitioning of trace elements among chemical associations in soils varied considerably for different elements. The highest percentage of Cd in soils, as estimated by sequential extraction, was associated with exchangeable fractions (25–41%), but the highest fraction of Zn (47%) was associated with resistant minerals. Uptake of trace elements by plants and solubility and mobility of these elements in the soil were affected to a greater extent by the plant species grown and soil pH, organic matter, and soil texture. Soil pH showed a significant but inverse relationship with the concentrations of most of the trace elements in plants. The addition of organic matter generally immobilized the trace elements in soils and caused reduction in plant uptake of most elements. A considerable proportion (up to 50%) of the total uptake of trace elements, and especially of Cd, was a result of atmospheric deposition. Ecological implications of contaminants in fertilizers and the resultant need for research are described.Key words: accumulation in soils, fertilizers, plant availability, soil properties, trace elements.
Effects of polychlorinated biphenyls, dibenzo-p-dioxins, and dibenzofurans on fish-eating birds
Authors: (Bart) Bosveld A. T. C. , Berg Martin Van den
Published: April 2011

Fish-eating birds are top predators at the end of the aquatic food chain. As such, they accumulate high concentrations of halogenated polycyclic aromatics like polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs). In this paper the levels and effects of these compounds on fish-eating birds are reviewed. To discuss the causal relationships between these compounds and the effects, dose–response studies in various bird species are reviewed. Neurotoxicity and effects on reproduction, embryonic respiration, mixed-function oxidase isoenzyme activities, and vitamin A and thyroid hormone levels are discussed. Using data from the literature, the lowest observed effect levels are calculated for different end points, and differences in sensitivity between the species are discussed.Key words: fish-eating birds, polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, polychlorinated biphenyls, reproductive impairment, cytochrome P-450.
Holocene vegetation history of Banks Island, Northwest Territories, Canada
Authors: Gajewski K , Mott R J , Ritchie J C , Hadden K
Published: April 2011

Four pollen diagrams from Banks Island, Northwest Territories, provide the first records of the postglacial vegetation of the region. Chronologies are estimated from radiocarbon dates and by correlation of the exotic-pollen curves to data from the mainland. The pollen stratigraphies from all sites can be divided into three zones, where the middle zone, dating from 7000 to 2000 BP, corresponds to the warmest time. Although both the first and third zones correspond to cooler periods, the vegetation of the earliest zone was not identical to that of the latest, indicated by lower frequencies of key pollen types such as those of Dryas and Saxifraga.Key words: Banks Island, Holocene, pollen diagram, Arctic, paleoecology, Quaternary.
Variation in sexual and clonal reproduction among introduced populations of flowering rush, Butomus umbellatus (Butomaceae)
Authors: Eckert Christopher G , Massonnet Blandine , Thomas Julia J
Published: April 2011

Butomus umbellatus L. is an invasive emergent aquatic plant that exhibits wide variation in seed production. Native European populations are fertile and diploid or sterile and triploid. However, adventive North American populations are widely reported to be sexually sterile. We quantified sexual fertility and self-compatibility under greenhouse conditions for nine introduced populations from eastern Ontario, Canada. All populations were highly fertile and self-compatible. Each flower produced an average of 127 ± 7 (mean ± SE) filled seeds and 31.4 ± 0.4% of seeds germinated. This level of fertility is much higher than previously reported, even for fertile native populations. We also quantified the production of seeds, flowers, and inflorescence-borne asexual bulbils in 19 natural populations from eastern Ontario; 17 populations were highly fertile (200 ± 9 seeds/fruit) and 2 produced almost no seeds (0.0-0.3 seeds/fruit), because ovules were either not fertilized or were aborted soon after fertilization. We found no evidence of a trade-off between sexual reproduction and clonal reproduction via bulbils. The wide variation in reproductive strategy observed in these populations raises questions concerning the evolutionary loss of sex in clonal populations, and may have significant implications for the spread and management of this exotic species.Key words: aquatic plants, clonal reproduction, breeding systems, invasive plants, reproductive ecology, sexual sterility.
Conversion of total to projected leaf area index in conifers
Authors: Barclay Hugh J , Goodman Doug
Published: April 2011

Several definitions of leaf area index (LAI) presently exist in the literature but the relationships among them are not clear. To compare the results of various studies, there is a need to convert from one definition to another. Factors for converting among four definitions of LAI are presented for six conifer species: Abies grandis (Dougl. ex D. Don) Lindl., Thuja plicata Donn ex D. Don., Tsuga heterophylla (Raf.) Sarg., Picea sitchensis (Bong.) Carr.), Pinus contorta Dougl., and Pseudotsuga menziesii (Mirb) Franco). Among the four definitions of LAI, the two extremes involve (i) the total area of the leaf and (ii) the projected area of nonhorizontal leaves, as they occur on the tree. If leaves are randomly oriented in space, then the conversion factor between definitions i and ii should be 0.25. Four of the six species have conversion factors very close to this value, and three of these four are relatively shade-intolerant,. The remaining two species, A. grandis and Thuja plicata, have conversion factors of approximately 0.35, owing to the approximately horizontal orientation of their leaves. These two species are both relatively shade-tolerant, and the trend toward horizontal leaves might be an adaptation to assist in shade tolerance. A sensitivity analysis indicated that the foliage of most of the species maximized the amount of light gathered when the light was coming from almost straight overhead, as is the case with many shaded forest trees.Key words: leaf area index, conifers, leaf area index conversion.
Analysis of genetic similarities among species of Fragaria, Potentilla, and Duchesnea found in northwest Argentina by using morphological, anatomical, and molecular characters
Authors: Ontivero Marta , Arias Marta , Ricci Juan Diaz , Babot Judith , Albornoz Patricia , Castagnaro Atilio
Published: April 2011

Morphological, anatomical, and molecular techniques were used to characterize wild strawberry and wild strawberry-like species in northwest Argentina. Characteristics of leaves, flowers, runners, achenes, and genomic DNA polymorphisms were used to analyze similarities among Potentilla tucumanensis Castagnaro & Arias, Duchesnea indica (Andr.) Focke, and Fragaria vesca L. Comparison of phenograms obtained by using morphological and anatomical traits or genomic DNA characters revealed similar clustering of the species. Both phenograms suggest that D. indica is more closely related to P. tucumanensis than to F. vesca. Using the randomly amplified polymorphic DNA (RAPD) technique with specific primers, we detected polymorphic bands that permit the identification of P. tucumanensis, D. indica, and F. vesca. In addition, we report new morphological and anatomical characters that can be used as diagnostic traits for better identification of species in reproductive and vegetative states.Key words: Fragaria, Potentilla, Duchesnea, RAPD, DNA fingerprinting, morphological traits, anatomical traits.
Daily and seasonal dynamics of airborne spores of Fusarium graminearum and other Fusarium species sampled over wheat plots
Authors: Fernando W GD , Miller J D , Seaman W L , Seifert K , Paulitz T C
Published: April 2011

Spores were sampled during 2 years over wheat plots at Ottawa, Ontario. Plots were treated with corn colonized with Gibberella zeae (Schwein.) Petch (anamorph Fusarium graminearum Schwabe). In 1994, viable spores were sampled with four Burkard high-throughput jet samplers. Gibberella zeae ascospores were recovered mostly at night and showed four main release events during the 20-day sampling period, 1-3 days after rain events. Highest density of G. zeae spores (1500 spores/m3) were sampled 1.5 m away from the inoculum source, with fewer spores 5 m away. Recovery of otherFusarium species was sporadic. For all species, there were no statistical differences among the daily sampling times, although for most species, morning counts were the lowest. Other Fusarium species detected, in decreasing order of spore density, were F. crookwellense, F. sporotrichioides, F. moniliforme, F. equiseti, F. subglutinans, and F. culmorum. Most spore release events did not correlate with rainfall events. In 1995, a Burkard continuous 7-day spore sampler was used to investigate the release of ascospores and macroconidia of G. zeae. Ascospores, but not macroconidia, showed a daily periodicity. Daily average densities of macroconidia were an order of magnitude less than ascospores. Ascospore release was correlated with rainfall events and the time of day.Key words: spore sampling,Gibberella zeae, Fusarium graminearum, Fusarium sp. ascospores, macroconidia.
Interspecific pollen transfer as a mechanism of competition: effect of Castilleja linariaefolia pollen on seed set of Ipomopsis aggregata
Authors: Caruso Christina M , Alfaro Monica
Published: April 2011

We investigated whether the deposition of Castilleja linariaefolia (Pursh) V. Grant pollen on flowers of Ipomopsis aggregata (Benth.) in DC. reduced I. aggregata's seed set. Ipomopsis flowers were hand-pollinated with either pure conspecific pollen (the control) or with C. linariaefolia pollen applied prior to, simultaneously with, or following conspecific pollen. Flowers that were simultaneously given C. linariaefolia and I. aggregata pollen received 39% less conspecific pollen than flowers in the control, but did not set fewer seeds per fruit. Flowers that were given C. linariaefolia pollen first received 30% less conspecific pollen and set 38% fewer seeds per fruit than the control. These results suggest that there is a priority effect; deposition of C. linariaefolia pollen on I. aggregata flowers results in competition, but only when C. linariaefolia pollen is deposited first. Unlike pollen of another competitor of I. aggregata (Delphinium nelsonii Greene. Per.), C. linariaefolia pollen caused competition without inducing an increased rate of stigma closure. Only 12% of I. aggregata's stigmas closed when C. linariaefolia pollen was deposited, and seed set of I. aggregata was reduced relative to the control whether their stigmas closed or not. The low rate at which C. linariaefolia pollen induces closure of I. aggregata's stigmas could be an adaptation to reduce the negative effects of competition.Key words: Castilleja linariaefolia, competition, hand pollination, hummingbirds, Ipomopsis aggregata, pollination.
Combined effects of disease and competition on plant fitness
Authors: Brunet Johanne , Mundt Christopher
Published: April 2011

Wheat genotypes susceptible to different races of a pathogen, Puccinia striiformis, were planted in pure stands and in three different 1:1 mixtures, in both the presence and absence of disease, in two sites, and over 3 years. Using analyses of variance, we tested whether disease and intergenotypic competition influenced a genotype's fitness and whether significant interactions existed between the effects of disease and competition on genotype fitness. Seed weight, number of inflorescences per seed planted, seeds per inflorescence, and absolute fitness were estimated for each genotype in each treatment. Absolute fitness was determined as the number of seeds collected per seed planted. Disease reduced seed weight. The other fitness measures were influenced by either disease or competition, and the impact of each factor often varied among site-year combinations. In general, interactions between the effects of disease and competition on genotype fitness were not significant. The few significant interactions indicated a less than additive effect of competition and disease on genotype fitness. The overall lack of interaction may be, in part, due to lesser disease levels in mixed as compared with pure stands, or reduced level of competition under diseased conditions.Key words: pathogens, competition, plant fitness, stripe rust, wheat.
In vitro spectrofluorometric determination of chlorophyll de novo synthesis in chlorophyll-deficient phenotypes of Pennisetum glaucum (L.) R.Br
Authors: Mantha Sailaja V , Karunasri Kosuri , Subrahmanyam Nekkalapudi C
Published: April 2011

Blocks in chlorophyll (Chl) biosynthesis in crude extracts of well-defined chlorophyll-deficient seedlings and green siblings from five Pennisetum glaucum (L.) R.Br. genotypes and the ability of these genotypes to relieve such blocks in crude extract mixtures were studied with low temperature (77 K) fluorescence spectroscopy. Dark-adapted green seedling extracts exhibited F657, F685, and F735 peaks corresponding with protochlorophyllide (Pchlide), Chl from photosystem II and from photosystem I, respectively. Extracts of white seedlings from white stripe mutants and an albino mutant exhibited F657 peaks indicative of Pchlide, whereas the extracts of yellow seedlings from yellow stripe mutants exhibited F657 and F678 peaks representing Pchlide and chlorophyllide (Chlide) accumulation, respectively. Addition of their green sibling's extract resulted in the appearance of F685 and F735 peaks, suggesting de novo relief of the blocks and photoreduction of Pchlide to Chl(ide). Incubating a mixture of crude extracts of yellow seedlings from two different yellow stripe mutants did not alter their peaks, indicating a lack of reconstitution because of a common limiting factor in the two yellow seedling sources. Likewise, the mixture of crude extract of yellow seedlings with that of white seedlings from white stripe mutants displayed no Chl peaks. Spontaneous greening in the mixture of crude extracts of yellow seedlings with that of albino mutant and its failure in other reconstitution experiments suggests that Chl synthase in albino seedlings enabled the conversion of Chlide to Chl in vitro. The factors governing the in vitro reconstitution and its implications in genetic complementation are discussed.Key words: chlorophyll-deficient mutants, blocks in chlorophyll biosynthesis, crude extracts, in vitro synthesis of chlorophyll.
Population genetic variation, structure, and evolution in Engelmann spruce, white spruce, and their natural hybrid complex in Alberta
Authors: Rajora Om P , Dancik Bruce P
Published: April 2011

Genetic variation, structure, and evolution of 12 populations of putative Engelmann spruce (Picea engelmanii Parry), white spruce (Picea glauca (Moench) Voss), and Engelmann - white spruce natural hybrids from the sympatric areas and two populations of white spruce from the allopatric areas in Alberta were examined using 23 allozyme loci coding for 13 enzymes in needles. Although most of the alleles were widespread, unique alleles were found in 9 of the 14 populations. No species-specific allele was observed. However, allele frequency differences were observed between the putative Engelmann and white spruce populations at a number of loci. Frequencies of 13 alleles showed significant correlation with altitude, those of 11 alleles showed correlation with latitude, and those of 3 alleles showed correlation with longitude. On average, 66.2% (99% criterion) of the loci were polymorphic, the number of alleles per locus was 1.88, the number of alleles per polymorphic locus was 2.88, and the observed and expected heterozygosities were 0.063 and 0.184, respectively. Genetic variability of allopatric white spruce, putative Engelmann, sympatric white spruce, and hybrid populations was quite comparable. The mean FSTestimate was 0.123 for the total populations. Canonical discriminant functions separated four putative Engelmann spruce populations from the fifth putative Engelmann spruce population and from the allopatric and sympatric white spruce and sympatric putative hybrid populations. A cluster analysis from genetic distances generally separated allopatric and sympatric white spruce populations from the putative Engelmann spruce and hybrid populations. A Wagner tree of the 14 populations produced two main branches; one branch consisting of two allopatric and two sympatric white spruce and one putative hybrid populations, and another branch consisting of the remaining nine spruce populations representing putative Engelmann spruce, putative hybrids, and sympatric white spruce. Putative hybrids showed lower distances to white spruce from the canonical discriminant analysis, whereas they showed lower distances to putative Engelmann spruce from the genetic distance analysis. High allozyme genetic identities between putative Engelmann and white spruce and allelic differentiation related to altitude in Alberta suggest that Engelmann spruce could at best be considered as a subspecies of Picea glauca, with white spruce named as Picea glauca ssp. glauca and Engelmann spruce named as Picea glauca ssp. engelmannii.Key words: Picea glauca, Picea engelmannii, biosystematics, natural hybridization, species differentiation, genetic divergence.
Microhabitat distribution of protostelids in temperate habitats in northwestern Arkansas
Authors: Moore Donna L , Spiegel Frederick W
Published: April 2011

Protostelids are unicellular slime molds that belong in a monophyletic group, the Eumycetozoa. A standardized technique was developed for the study of protostelid communities from the leaf litter and aerial microhabitats of forests and grasslands in northwestern Arkansas. Protostelium mycophaga Olive and Stoian and Soliformovum irregularis (Olive and Stoian) Spiegel were more abundant in grasslands, while Schizoplasmodiopsis pseudoendospora Olive, Martin, and Stoian, Nematostelium ovatum (Olive and Stoian) Olive and Stoian, and Echinosteliopsis oligospora Reinhard and Olive were more abundant in forests. Some species of protostelids exhibited a preference for either the aerial microhabitat, e.g., P. mycophaga and Soliformovum irregularis, or the litter microhabitat, e.g., N. ovatum and Schizoplasmodiopsis pseudoendospora. Other species, including Cavostelium apophysatum Olive, Tychosporium arachisporum Spiegel, Moore, and Feldman, and Schizoplasmodium cavostelioides, were present in both microhabitats.Key words: ecology, mycetozoans, protoctists, slime molds.
Phaeocollybia in western North America. I. ThePhaeocollybia kauffmaniicomplex
Authors: Norvell Lorelei L
Published: April 2011

Morphological and molecular investigations during a taxonomic reevaluation of the genus Phaeocollybia revealed four new agaric species from British Columbia, Washington, Oregon, and California that are morphologically similar to Phaeocollybia kauffmanii (Smith) Singer. All five species produce large basidiomes with brown pilei, stipes with cartilaginous rinds surrounding dense pith, vertical-monopodial pseudorhizae, large, verrucose or verruculose, apically beaked basidiospores, and thin-walled, clavate cheilocystidia. The most salient morphological characters distinguishing the new species from P. kauffmanii include abundant clamp connections (Phaeocollybia ammiratii), a pink- or purple-brown pileus lacking encrusting pigments in the pileipellis (Phaeocollybia benzokauffmanii), a nonviscid, fibrillose, ochraceous pileus with a trilaminate pileipellis (Phaeocollybia luteosquamulosa), and unusually large basidiospores and subglobose subcapitate pedicellate cheilocystidia (Phaeocollybia redheadii). An emended description of P. kauffmanii accompanies technical descriptions and a key to the five species and newly revealed complex.Key words: Agaricales, Basidiomycota, Cortinariaceae, RFLPs, temperate rainforest.