bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Prior Acid Exposure on Physiological Responses of Juvenile Rainbow Trout (Salmo gairdneri) to Acute Handling Stress
Authors: Barton Bruce A. , Weirter Gary S. , Schreck Cars B.
Published: September 2008

Acid-stressed fish appear to be more sensitive to additional stressors than unstressed fish. When juvenile rainbow trout, Salmo gairdneri, were exposed to acid conditions (pH 5.7–4.7) for 5 d, plasma cortisol was affected only slightly during the initial hours of exposure, but plasma glucose and hematocrit increased, and plasma sodium decreased. However, when fish held at pH 4.7 were subsequently subjected to a 30-s handling stress, poststress plasma cortisol rose to a peak level of more than twice that in handled fish held at ambient pH (6.6). Effects of handling on plasma glucose or sodium were not apparent against levels already altered by the chronic acid exposure, judging by the corticosteroid response, we conclude that the acid-stressed fish were more sensitive to additional handling, even though they appeared to be physiologically normal after 5 d. Thus, as a management consideration, when fish are stocked in acidified waters, care should be taken to avoid situations where the fish may encounter additional disturbances in the new environment. Plasma glucose and sodium were better indicators of chronic acid stress alone than plasma cortisol, but the greater cortisol response to handling at low pH may be a useful method of detecting increased interrenal activity during early stages of environmental acidification.
Apparent Stock Recruitment Relationships in Mixed Stock Fisheries
Authors: Hilborn R.
Published: September 2008

When several stocks of differing productivities are fished together and combined for stock recruitment analysis, the estimated productivity and size of the stock depends strongly on the previous exploitation history. As a mixed stock is harvested harder, it appears smaller in total size but more productive per individual. I analysed the mechanism behind this change. Passive feedback management policies perform well on mixed stocks, when starting from unexploited conditions. When starting from an overexploited condition, passive feedback management will fail to allow the less productive stocks to recover and will maintain overexploitation. This is also true in the presence of straying between stocks. Since few salmon fisheries operate on single stocks, stock recruitment analyses will usually underestimate the optimum escapement and overestimate the optimum harvest rate when mixed stocks are treated as a single stock. These conclusions will be true for any mixed stock fishery with different productivities of the stocks.
Postsettlement Diatom Succession in the Bay of Quinte, Lake Ontario
Authors: Stoermer E. F. , Wolin J. A. , Schelske C. L. , Conley D. J.
Published: September 2008

Siliceous algal microfossil assemblages deposited in the Bay of Quinte prior to European settlement consist of low numbers of benthic diatoms and chrysophyte cysts. Early settlement activities are marked by qualitative changes in the flora and small increases in microfossil flux. Events associated with the Ambrosia horizon produced a rapid transition from assemblages characteristic of oligotrophy environments to those characteristic of eutrophic waters and a large increase in microfossil flux. This was followed by a period of decreasing siliceous microfossil flux and reestablishment of less eutrophic species ca. 1853–61. Minimum siliceous algal microfossil flux and highly atypical assemblages occurred in the period ca. 1879–88, which corresponds to the period of intensive mining activities in the Bay of Quinte watershed. Maximum flux of siliceous microfossils occurred ca. 1900 and declined thereafter, although composition of assemblages deposited indicates increasing eutrophy and displacement of summer-blooming species. We interpret this as evidence of beginning of summer silica limitation. Based on microfossil evidence, the modern eutrophic flora of the bay was established by 1928.
Sea Lamprey (Petromyzon marinus) Populations in Northeastern North America: Genetic Differentiation and Affinities
Authors: Wright Janet , Krueger Charles C. , Brussard Peter F. , Hail Marjorie Collings
Published: September 2008

We examined genetic population structure in 3253 sea lampreys (Petromyzon marinus) sampled at 53 sites in northeastern North America and the British isles. Hierarchical F-statistics of allozyme frequencies indicated that genetic divergence from lake to lake and river to river was greater than divergence among sites within fakes or rivers and also greater than that attributable to the separation of landlocked freshwater from coastal anadromous systems. Lampreys from different lakes varied considerably in the amount of spatial differentiation evident. New York freshwater populations of uncertain invasion history were no more genetically differentiated than were recently introduced upper Great Lakes populations. The apparent reproductive isolation of lampreys in Lake Erie from Lake Ontario populations, despite canal connections, suggests that movement is limited between lakes. Future studies should determine the cause so that management techniques to restrict movement can be developed to control populations.
Visual Prey Detection and Foraging in Sympatric Cutthroat Trout (Salmo clarki clarki) and Dolly Varden (Salvelinus malma)
Authors: Henderson M. A. , Northcote T. G.
Published: September 2008

In sympatric lacustrine cutthroat trout (Salmo clarki clarki) and Dolly Varden (Salvelinus malma), reaction distance to artificial and natural prey increased with increases in irradiance from a visual irradiance threshold (VIT, the maximum quantity of irradiance resulting in zero reaction distance to prey) to a saturation irradiance threshold (SIT, the minimum quantity of irradiance that maximizes reaction distance to prey). The VIT and SIT for Dolly Varden were approximately one and two orders of magnitude lower, respectively, than those for trout. At all irradiance levels >4.2 × 1017 photons m−2∙s−1 the reaction distance of trout exceeded that of Dolly Varden. Reaction distance to prey in both species was greatest for red irradiance followed in descending order by green, yellow and blue irradiance. The midsummer ambient irradiance regime in a lake cohabited by trout (concentrated in surface waters) and Dolly Varden (inhabiting deeper waters) showed that during daylight hours a much larger portion of the water column had irradiance levels [Formula: see text] the SIT of Dolly Varden than the SIT of trout and that irradiance levels were always [Formula: see text] the VST of Dolly Varden although only in the upper 5 m at night. Estimates of reaction distance to Diaptomus kenai and foraging velocity at several irradiance levels showed that trout have the potential to visually search a volume of water seven times greater than that searched by Dolly Varden for Diaptomus kenai on a summer day.
Sediment Accumulation Rates in an Alaskan Arctic Lake Using a Modified 210Pb Technique
Authors: Cornwell Jeffrey C.
Published: September 2008

Because of high concentrations of authigenic Mn and Fe oxides in surficial sediments from Toolik Lake, Alaska, the normalization of depth and 210Pb activity scales to the sediment Al content was used for sediment accumulation rate calculations. These results are compared with the conventional 210Pb dating technique. I found the flux of 210Pb to the lake to be very low (10 dpm∙cm−2∙yr−1), and excess 210Pb is restricted to the top 5 cm of sediment. The whole lake sediment accumulation rate is about 2.7 mg∙cm−2∙yr−1 and the sediments are little disturbed by physical or biological processes. Low rates of physical and chemical weathering are responsible for the low sediment accumulation rates.
Catch-Age Analysis with Auxiliary Information
Authors: Deriso R. B. , Quinn II T. J. , Neal P. R.
Published: September 2008

We examined the use of catch-at-age data for estimating population abundance, productivity, and year-class abundance. A review section is included where various published models and our new models are shown to form a cohesive theory of catch-at-age analysis linked by level of model complexity. We developed three new models with different error structures: a log-normal measurement error model, a multinomial measurement error model, and a log-normal process error model. By application to data on Pacific halibut (Hippoglossus stenolepis), we show that moderate amounts of auxiliary information, such as fishing effort data or the assumption of a spawner–recruit relationship, are needed to stabilize estimates. The models performed very similarly with moderate amounts of auxiliary information, suggesting a degree of robustness to the underlying error structure. We also developed an extension to classic catch-curve analysis that estimates relative year-class strength reasonably well.
A Critique of the In stream Flow Incremental Methodology
Authors: Mathur Dilip , Bason William H. , Purdy Jr. Edmund J. , Silver Carl A.
Published: September 2008

A review and reanalysis of the published literature show that several assumptions are violated in the application of the Instream Flow Incremental Methodology (IFIM) without consideration of the implications of so doing. The fundamental assumption of a positive linear relationship between "potential available habitat" (WUA) and biomass of fish has neither been documented nor validated, particularly in warmwater streams. Absence of correlation precludes prediction of changes in fish populations. In some studies the test of this assumption appears to be equivalent to a calibration operation. The other assumption violated includes independent selection of habitat variables by fish. The presence of significant interaction among habitat variables can affect the stream flow recommendations. Another problem exists in application of Physical Habitat Simulation (PHABSIM): one WUA unit should not be interpreted as being equal to another in biological production or habitat value unless shown to be an exact replica. Several combinations of physical variables could give rise to the same amount of WUA, none of which may be correlated to the biomass of fish. The utilization, suitability, or preference curves should not be treated as probability functions; a rating of 1.0 is not equivalent to probability of 1.0. Care should be taken to distinguish between real behavioral preferences of fishes based on distributional occurrence from abundance (relative or absolute size) in a stream.
A Sensitivity Analysis of Deriso's Delay-Difference Equation Using Simulation
Authors: Tyler Albert V. , Sebring Linda L. , Murphy Margaret C. , Murphy Lea F.
Published: September 2008

The degree to which the delay-difference equation can track biomass changes of fish stocks was examined using a sensitivity analysis technique in conjunction with a simulation model having explicit age-class structure. The simplicity of the delay-difference equation results from the manner in which it subsumes age-class structure by using two parameters, one for mortality and one for growth. The changes in biomass in a simulated stock were followed closely by the equation when error-free determinations of stock parameters were transferred from the simulated stock to the equation, even when a high degree of density dependence was allowed in the growth rate, and in some cases when there were large differences in age-specific mortality in the simulated stock. When error was induced in the stock parameters, the delay-difference equation was fairly robust in estimating biomass with mortality rate and growth rate simultaneously either above the true value or below the true value. Good biomass estimates also resulted when growth rate was at the true value and mortality rate was above the true value. Poor biomass estimates resulted when mortality was overestimated while growth was underestimated, or vice versa.
Effect of Sulfite Dechlorination on the Accumulation of Waterborne Lead by Rainbow Trout (Salmo gairdneri)
Authors: Hodson Peter V. , Spry Douglas J.
Published: September 2008

Chlorine can be removed from laboratory water supplies by reduction with sodium sulfite, but sulfite complexation of metals may bias aquatic toxicity tests. We tested the effect of waterborne sulfite on the accumulation of waterborne lead by rainbow trout (Salmo gairdneri). After 96 h, the blood lead levels of trout exposed to both 100 μg lead/L and 440 μg sodium sulfite/L were lower than those exposed to lead alone. The highest level of sodium sulfite having no effect on blood lead was 20 μg/L. The addition of 200–300 μg sodium sulfite/L to our water supply after charcoal filtration removed residual chlorine levels rapidly and completely. This reaction, and other possible reactions with organic matter, always reduced measureabie sulfite levels to less than 1 μg/L (limit of detection), a level much lower than those tested. Hence, sulfite dechlorination should not interfere with metal bioassays.
An uncommon H3/Ser10 phosphorylation pattern inCestrum strigilatum(Solanaceae), a species with B chromosomes
Authors: Fernandes Thiago , Yuyama Priscila Mary , Moraes Ana Paula , Vanzela André Luís Laforga
Published: September 2008

Cestrum strigilatum (Solanaceae) is a South American shrub with B chromosomes. Bs show a univalent behavior when a single B is present, have non-Mendelian segregation, and are poor in genes and rich in repetitive DNA. In this study, the histone H3 at serine 10 (H3/Ser10) phosphorylation pattern was investigated during mitosis and meiosis of C. strigilatum collected from the wild and was compared in A and B chromosomes. The results revealed that H3/Ser10 phosphorylation of A chromosomes occurred only in the pericentromeric region in both mitosis and meiosis, whereas in the B univalent, phosphorylation appeared in almost the whole extent of the chromosome, except in the terminal portion of the long arm. In meiosis II, the phosphorylation of A chromosomes was similar to that in the first division of meiosis, but the Bs did not show H3/Ser10 phosphorylation. Our results suggest that phosphorylation at the pericentromeric region may be associated with chromosome motility during cell divisions and with the cohesion of B chromatids in a univalent structure in meiosis I.
Functional markers for selection of potyvirus resistance alleles at the pvr2-eIF4E locus in pepper using tetra-primer ARMS–PCR
Authors: Rubio Manuel , Caranta Carole , Palloix Alain
Published: September 2008

Functional markers targeted on single nucleotide polymorphisms (SNPs) responsible for phenotypic variation constitute optimal tools for marker-assisted selection (MAS) of resistance alleles with different specificities. Here, we used the tetra-primer ARMS–PCR procedure to assay SNP signatures of four distinct alleles at the pvr2-eIF4E locus, which controls pepper resistance to several potyviruses. These simple, economical, and codominant markers open the way for MAS of pepper genotypes resistant to the potyviral strains and species that are prevalent in distinct cultivation areas across the world.
Development of Triticum turgidum subsp. durum – Aegilops longissima amphiploids with high iron and zinc content through unreduced gamete formation in F1 hybrids
Authors: Tiwari Vijay K. , Rawat Nidhi , Neelam Kumari , Randhawa Gursharn S. , Singh Kuldeep , Chhuneja Parveen , Dhaliwal Harcharan S.
Published: September 2008

Four different interspecific hybrids involving three different accessions of Aegilops longissima Schweinf. & Muschl. with high grain iron and zinc content and three Triticum turgidum L. subsp. durum (Desf.) Husn. cultivars with low micronutrient content were made for durum wheat biofortification and investigated for chromosome pairing, fertility, putative amphiploidy, and micronutrient content. The chromosome pairing in the 21-chromosome F1 hybrids (ABSl) consisted of 0–6 rod bivalents and occasionally 1 trivalent. All the F1 hybrids, however, unexpectedly showed partial but variable fertility. The detailed meiotic investigation indicated the simultaneous occurrence of two types of aberrant meiotic divisions, namely first-division restitution and single-division meiosis, leading to regular dyads and unreduced gamete formation and fertility. The F2 seeds, being putative amphiploids (AABBSlSl), had nearly double the chromosome number (40–42) and regular meiosis and fertility. The F1 hybrids were intermediate between the two parents for different morphological traits. The putative amphiploids with bold seed size had higher grain ash content and ash iron and zinc content than durum wheat cultivars, suggesting that Ae. longissima possesses a better genetic system(s) for uptake and seed sequestration of iron and zinc, which could be transferred to elite durum and bread wheat cultivars and exploited.
Genetic diversity of the azuki bean (Vigna angularis(Willd.) Ohwi & Ohashi) gene pool as assessed by SSR markers
Authors: Xu H. X. , Jing T. , Tomooka N. , Kaga A. , Isemura T. , Vaughan D. A.
Published: September 2008

To facilitate the wider use of genetic resources including newly collected cultivated and wild azuki bean germplasm, the genetic diversity of the azuki bean complex, based on 13 simple sequence repeat (SSR) primers, was evaluated and a core collection was developed using 616 accessions originating from 8 Asian countries. Wild germplasm from Japan was highly diverse and represented much of the allelic variation found in cultivated germplasm. The SSR results together with recent archaeobotanical evidence support the view that Japan is one center of domestication of azuki bean, at least for the northeast Asian azuki bean. Cultivated azuki beans from China, Korea, and Japan were the most diverse and were genetically distinct from each other, suggesting a long and relatively isolated history of cultivation in each country. Cultivated azuki beans from eastern Nepal and Bhutan were similar to each other and quite distinct from others. For two primers, most eastern Nepalese and Bhutanese cultivated accessions had null alleles. In addition, wild accessions from the Yangtze River region of China and the Himalayan region had a null allele for one or the other of these primers. Whether the distinct diversity of azuki bean in the Himalayan region is due to introgression or separate domestication events requires further study. In contrast, western Nepalese azuki beans showed an SSR profile similar to that of Chinese azuki beans. The genetic distinctness of cultivated azuki beans from Vietnam has been revealed for the first time. The specific alleles indicate that Vietnamese azuki beans have been cultivated in isolation from Chinese azuki beans for a long time. Wild germplasm from the Himalayan region showed the highest level of variation. Based on the results, Himalayan germplasm could be considered a novel gene source for azuki bean breeding. A comparison with mungbean SSR analysis revealed that the mean gene diversity of cultivated azuki bean (0.74) was much higher than that of cultivated mungbean (0.41). The reduction in gene diversity due to domestication, the domestication bottleneck, in azuki bean is not strong compared with that in mungbean.
Genetic recombination in Sorghum bicolor × S. macrospermum interspecific hybrids
Authors: Kuhlman Les C. , Burson Byron L. , Klein Patricia E. , Klein Robert R. , Stelly David M. , Price H. James , Rooney William L.
Published: September 2008

Sorghum has been improved by public and private breeding programs utilizing germplasm mostly from within the species Sorghum bicolor . Until recently, cross-incompatibilities have prevented hybridization of S. bicolor with most other species within the genus Sorghum . Utilizing germplasm homozygous for the iap allele, hybrids were readily produced between S. bicolor (2n = 20; AAB1B1) and S. macrospermum (2n = 40; WWXXYYZZ). These hybrids were intermediate to the parents in chromosome number (2n = 30) and overall morphology. Meiosis in both parents was regular; S. bicolor had 10 bivalents per pollen mother cell (PMC) and S. macrospermum had an average of 19.96 bivalents per PMC. Six hybrids were studied cytologically and meiosis was irregular, with the chromosomes associating primarily as univalents and bivalents. There was an average of 3.54 bivalents per PMC, with a range of 0–8 bivalents, most of which were rods (98%). Using FISH (fluorescent in situ hybridization), moderate levels (2.6 II per PMC) of allosyndetic recombination were observed. Genomic relationships were sufficient to assign S. macrospermum the genomic formula AAB1B1YYZZ (Y and Z remain unknown). Allosyndetic recombination in the interspecific hybrids indicates that introgression through genetic recombination should be possible if viable backcrosses can be recovered.
Development and testing of a low sludge discharge membrane bioreactor for greywater reclamation
Authors: Young Stephanie , Xu Aotian
Published: September 2008

A low sludge discharge membrane bioreactor (LSDMBR) for greywater reclamation was developed and tested in this study. LSDMBR was designed by combining an aerobic activated sludge process with an immersed membrane filtration process. LSDMBR offers the following advantages over conventional activated sludge processes. Firstly, LSDMBR has a high biomass concentration attributed to membrane filtration of the effluent and low sludge wasting, which results in reduced disposal costs. Secondly, LSDMBR provides for a favorable environment for nitrifying bacteria and the promotion of their growth. Finally, LSDMBR provides for higher treatment efficiencies and produces higher-quality effluent for reuse over conventional processes. It was found from laboratory testing that the contaminant removal efficiencies achieved by LSDMBR within 2.5 h of hydraulic retention time (HRT) were as follows: 95% removal of anionic surfactants and 90% removal of 5-day biochemical oxygen demand (BOD5), respectively. It was also found that the effluent ammonia and total Kjeldahl nitrogen (TKN) concentrations were reduced to less than 1 mg/L and 6 mg/L, respectively. Results of the study suggested that LSDMBR is a small-scale and self-sustaining greywater reclamation system that requires low installation space and low sludge discharge.
Stream ecosystem health in rural mixed land-use watersheds
Authors: Brisbois Marie Claire , Jamieson Rob , Gordon Robert , Stratton Glenn , Madani Ali
Published: September 2008

A paired stream approach was used to assess ecosystem health in two rural Nova Scotia streams (Thomas Brook and Sharpe Brook) with varying land-use practices. The objectives of the study were to assess stream health within an agricultural catchment, the Thomas Brook Watershed, and to identify parameters that could be used to characterize the impacts of agricultural land use on stream ecosystem health within intensively farmed watersheds in Nova Scotia. General water quality (nutrient concentrations, turbidity, pH, temperature) and the hydrology of both watersheds were monitored from May to October 2006. In addition, continuous dissolved oxygen (DO) and chlorophyll a data were collected in both streams, and benthic invertebrate populations were characterized during the study period. Diurnal DO data were analyzed to determine photosynthesis and respiration ratios. Macroinvertebrate data provided information on productivity, and on a number of other relevant metrics. Findings determined that agricultural land-use generally led to high nutrient concentrations, large dissolved oxygen variability, turbid waters, high chlorophyll a content, and impacted macroinvertebrate populations in streams. Forested land-use demonstrated typically unimpacted conditions. It was concluded that DO dynamics and macroinvertebrate metrics would be very useful for providing a generalized assessment of stream health in agricultural watersheds.
Use of dairy sludge for the removal of some basic dyes
Authors: Sumanjit  , Walia Tejinder Pal Singh
Published: September 2008

Dairy sludge, which is produced as a result of the activated sludge process, used in the dairy processing industries for treating their effluents, is a low cost, locally available and relatively new adsorbent. It is being investigated for its capacity to remove some of the basic dyes such as aniline blue, crystal violet, malachite green, methylene blue, rhodamine-B, and safranine from aqueous solutions. The effects of various experimental parameters;; initial pH, dye concentration, sorbent dosage, ion strength, and contact time, were examined and optimal experimental conditions were decided. At initial basic pH of 10, all six of the dyes studied could be removed effectively and in a very short period of time of just 35 min. The isothermal data for adsorption followed the Freundlich and Langmuir models. The adsorption results in this study indicated that all the dyes studied in this work can be easily removed by the application of dairy sludge.
Process water treatment in Canada’s oil sands industry: II. A review of emerging technologies
Authors: Allen Erik W.
Published: September 2008

Canada’s oil sands industry uses large volumes of freshwater to extract bitumen from surface-mined ore. With oil production expected to increase 3-fold over the next decade, process water treatment has become a critical issue for oil sands operators, both in terms of sustaining bitumen recovery and protecting freshwater resources. To identify candidate treatment technologies, a review was conducted on the state-of-the-art of water treatment in the oil industry. Significant developments include (i) chemical modifications to adsorbents and membranes to improve pollutant removal and reduce fouling;; (ii) hybridization of adsorbent, membrane, and bioreactor technologies to enhance the biological treatment of toxic feedwaters;; (iii) advances in photocatalytic oxidation of organic compounds;; and (iv) implementation of large-scale treatment wetlands to treat hydrocarbon-contaminated wastewaters. In adapting treatment technologies to the oil sands, operators will need to consider the fouling potential of bitumen and fine clays, the effect of process water alkalinity on treatment performance, and the biodegradability of toxic organic compounds.
Field-scale treatment of landfill gas with a passive methane oxidizing biofilter
Authors: Philopoulos Andrew , Felske Christian , McCartney Daryl
Published: September 2008

Municipal solid waste landfills are a major contributor to global methane emissions, a potent greenhouse gas. A treatment alternative was evaluated by installing three biogenic methane oxidizing biofilters into the landfill cover at the Leduc and District Regional Landfill (Alberta). Mature yard-waste compost was used as the biofilter medium. The results, collected over a period of 10 months, showed that two sites performed well as low surface emissions (<15 g CH4 m–2 d–1) were observed on 6 of 8 monitoring events. These two sites also demonstrated sufficient temperature (>20 °C) and moisture (>0.25 L L–1) levels to support a high level of biogenic activity, the former despite cold winter temperatures (<0 °C). The third site showed low calculated methane influent flows (<5 g CH4 m–2 d–1) and therefore observations of performance were limited.
Investigation on the use of nitrified wastewater for the steady-state operation of a biotrickling filter for the removal of hydrogen sulphide in biogas
Authors: Soreanu Gabriela , Béland Michel , Falletta Patricia , Edmonson Kara , Seto Peter
Published: September 2008

A biological process for the removal of hydrogen sulphide (H2S) in digester biogas was investigated using nitrified municipal wastewater as a nutrient solution under anoxic conditions. Biogas was continuously fed into a 0.012 m3 biotrickling filter at an H2S loading rate of approximately 1.50 g/d, counter-current to the nutrient solution. A zero-order macro-kinetic process was established on the basis of the degradation and formation rates for N and S species. The process performance was dependent on the presence of nitrate at low concentrations (in the order of 20 mg N-NO3–/L) found to be sufficient to maintain maximum H2S removal efficiency (>99%) under steady-state conditions where nitrate degradation rate was constant. The developed process has the potential to be adopted as an attractive alternative for biogas cleaning and, in some cases, with simultaneous wastewater denitrification. The information contained within this paper may be used as a basis for further research and (or) in the design of a scaled-up process.
Removal of Cr(VI) from wastewater using activated tamarind seeds as an adsorbent
Authors: Babu B.V. , Gupta Suresh
Published: September 2008

In the present study, an adsorbent was prepared from tamarind seeds and batch studies were conducted for Cr(VI) removal from aqueous solutions. Tamarind seeds were activated by heat treatment and with concentrated sulfuric acid (98% w/w). The parameters investigated include initial pH, contact time, initial Cr(VI) concentration, and adsorbent dosage. The adsorption of Cr(VI) was found to be maximum at low values of initial pH in the range of 1–3. The adsorption process of Cr(VI) was tested with Langmuir and Freundlich isotherm models. Application of the Langmuir isotherm to the systems yielded maximum adsorption capacity of 29.08 mg g–1. The adsorption process followed second order kinetics and the corresponding rate constant was found to be 0.0026 g mg–1 min–1.
Méthodologie pour l’adaptation de données physiographiques canadiennes au modèle de qualité de l’eau SWAT « soil water assessment tool »
Authors: Lévesque Étienne , Lamontagne Luc , Van Griensven Ann , Vanrolleghem Peter A. , Anctil François
Published: September 2008

La modélisation hydrologique est un outil d’aide à la décision de premier plan à considérer dans un contexte de gestion intégrée de l’eau par bassin versant au Canada. Un protocole de mise en place unique et largement transférable de ces modèles est à privilégier pour faciliter la gestion de l’eau des bassins versants prioritaires. L’objectif des présents travaux est de proposer une approche visant à adapter les formats des données physiographiques actuellement disponibles aux formats exigés par le modèle de qualité de l’eau SWAT « soil water assessment tool ». Les critères de sélection d’un modèle numérique de terrain, d’un réseau hydrographique numérisé, de cartes d’occupations du territoire et des sols sont présentés. Des correspondances entre des classes d’occupations du territoire d’usage courant au Canada et celles requises dans la base de données de SWAT sont proposées. La méthodologie pour établir une typologie des sols est explicitée. La subjectivité inhérente dans la subdivision du bassin versant en sous-bassins, puis dans la distribution des unités de réponse hydrologique et la sensibilité des sorties du modèle au niveau de détail des produits cartographiques utilisés est discutée.
Cyanobacterial bioactive molecules — an overview of their toxic properties
Authors: Jaiswal Pranita , Singh Pawan Kumar , Prasanna Radha
Published: September 2008

Allelopathic interactions involving cyanobacteria are being increasingly explored for the pharmaceutical and environmental significance of the bioactive molecules. Among the toxic compounds produced by cyanobacteria, the biosynthetic pathways, regulatory mechanisms, and genes involved are well understood, in relation to biotoxins, whereas the cytotoxins are less investigated. A range of laboratory methods have been developed to detect and identify biotoxins in water as well as the causal organisms; these methods vary greatly in their degree of sophistication and the information they provide. Direct molecular probes are also available to detect and (or) differentiate toxic and nontoxic species from environmental samples. This review collates the information available on the diverse types of toxic bioactive molecules produced by cyanobacteria and provides pointers for effective exploitation of these biologically and industrially significant prokaryotes.
Colonization of barley roots by endophytic fungi and their reduction of take-all caused by Gaeumannomyces graminis var. tritici
Authors: Maciá-Vicente Jose G. , Jansson Hans-Börje , Mendgen Kurt , Lopez-Llorca Luis V.
Published: September 2008

Fungal root endophytes obtained from natural vegetation were tested for antifungal activity in dual culture tests against the root pathogen Gaeumannomyces graminis var. tritici. Fifteen isolates, including Acremonium blochii , Acremonium furcatum , Aspergillus fumigatus , Cylindrocarpon sp., Cylindrocarpon destructans , Dactylaria sp., Fusarium equiseti, Phoma herbarum , Phoma leveillei , and a sterile mycelium, selected based on the dual culture test, were inoculated on barley roots in growth tubes under axenic conditions, both in the absence and presence of G. graminis var. tritici. All isolates colonized the rhizosphere and very often the root cortex without causing disease symptoms and without affecting plant growth. Eight isolates significantly reduced the symptoms caused by G. graminis var. tritici, and 6 of them reduced its presence in the roots.
Candida albicans-secreted lipase induces injury and steatosis in immune and parenchymal cells
Authors: Paraje María Gabriela , Correa Silvia Graciela , Renna María Sol , Theumer Martín , Sotomayor Claudia Elena
Published: September 2008

Virulence depends on opposing reactions between host and pathogen and is intrinsically linked to the host immune status. Virulence factors rely upon microbial attributes that mediate cell damage. While the activity of several Candida albicans hydrolytic enzymes is well characterized, the biological role of lipases is uncertain. In this report, we identified, isolated, and characterized a C. albicans 70 kDa lipase that exhibited maximal activity at physiological pH and temperature. We evaluated the ability of C. albicans lipase to interact with two types of mammalian host cells: macrophages, as crucial immune effector cells involved in fungal control, and hepatocytes, as examples of parenchymal cells compromised during fungal dissemination. Herein, we demonstrate for the first time that an extracellular lipase released by C. albicans directly induced cytotoxicity and promoted the deposition of lipid droplets in the cytoplasm of macrophages and hepatocytes
Revival of saprotrophic and mycorrhizal basidiomycete cultures after 20 years in cold storage in sterile water
Authors: Richter Dana L.
Published: September 2008

Vegetatively colonized agar cores of 69 basidiomycete fungus isolates (48 species in 30 genera and 17 families) were stored at 5 °C in tubes of sterile distilled water without manipulation for 20 years. These were represented by 34 isolates of saprotrophic fungi (29 species in 19 genera) and 35 isolates of mycorrhizal fungi (19 species in 11 genera). Viability was evaluated based on revived growth on agar media at room temperature. Fifty-seven of the 69 isolates (82.6%) grew vigorously when revived after storage for 20 years; of the 34 saprotrophic fungus isolates, 30 revived (88.2%); of the 35 mycorrhizal fungus isolates, 27 revived (77.1%). Thirteen isolates of Laccaria were all viable after 20 years, indicating cold storage in sterile water to be a good method for maintaining this important genus of mycorrhizal fungi. In general, however, mycorrhizal fungus species demonstrated lower viability than saprotrophic fungi.
Modulation of Lactobacillus casei in ileal and fecal samples from healthy volunteers after consumption of a fermented milk containingLactobacillus caseiDN-114 001Rif
Authors: Rochet Violaine , Rigottier-Gois Lionel , Levenez Florence , Cadiou Julie , Marteau Philippe , Bresson Jean-Louis , Goupil-Feillerat Nathalie , Doré Joël
Published: September 2008

Lactobacillus casei DN-114 001 is a probiotic strain able to interact with the immune system and to interfere with gastrointestinal pathogens. The derived strain DN-114 001Rifwas studied during its transit through the upper and distal intestine of human volunteers. Seven volunteers participated in the study, which involved intestinal intubation to sample ileal contents and collection of fecal samples, with a wash-out period of 8 days between the 2 steps. The retrieval of the probiotic was analyzed in the ileum every 2 h for 8 h following the ingestion of one dose of the test product and in the feces prior to, during, and after daily consumption of the test product for 8 days. Persistence of the probiotic amplifiable DNA was assessed using temporal temperature gradient gel electrophoresis and real-time PCR. Fluorescent in situ hybridization allowed analysis of the composition of the dominant digestive microbiota. The ingestion of L. casei DN-114 001Rifled to a significant and transient increase of its amplifiable DNA in ileal and fecal samples. This is related to a high stability in the composition of dominant groups of the gut microbiota. Data from ileal samples are scarce and our study confirms the potentiality for interaction between probiotics and the human immune system.
Genetic diversity among Mycobacterium tuberculosis isolates from Mexican patients
Authors: Vázquez-Marrufo G. , Marín-Hernández D. , Zavala-Páramo M. G. , Vázquez-Narvaez G. , Álvarez-Aguilar C. , Vázquez-Garcidueñas M. S.
Published: September 2008

Forty-six isolates of the Mycobacterium tuberculosis complex were typified by PCR of the IS6110 region and by Mycobacterium bovis specific primers JB21/JB22. Isolate MVG01 was typified as M. bovis, being the first record of a case of human tuberculosis caused by this species in Mexico. RAPD–PCR was used to describe the genetic diversity of the remaining 45 M. tuberculosis complex isolates. The corrected genotypic diversity value calculated for the analyzed population was 0.96, the estimated mean gene diversity was 0.235, and the corrected Shannon–Weiner index was 2.15. All allele–loci combinations generated showed significant linkage disequilibria. The distribution of genetic variation was analyzed both by the unweighted pair group method with arithmetic averages clustering and by principal coordinates analysis. Unweighted pair group method with arithmetic averages clustering resulted in a tree with four main clusters and one unclustered strain (MVG20), the principal coordinates analysis strain distribution pattern being consistent with this grouping. The obtained results suggest that the studied isolates belong to a clonal population having significant genetic diversity. Our genetic diversity results are comparable with those reported for other populations of M. tuberculosis, although only three RAPD primers were used.
Biological treatment and toxicity of low concentrations of oily wastewater (bilgewater)
Authors: Stamper David M. , Montgomery Michael T.
Published: September 2008

The biodegradability and toxicity of low concentrations of oily wastewater (bilgewater) were tested under simulated sanitary wastewater treatment conditions. This was done to establish the feasibility of a combined shipboard oily and nonoily wastewater treatment system. The biodegradability of oily wastewater was determined by proxy;14C-labeled dodecane, toluene, and phenanthrene (representing alkane, aromatic, and polyaromatic compounds, respectively) were mineralized in petroleum fuels and lubricants. We found that low concentrations of oily wastewater components were mineralized, even in the presence of more abundant substrates (such as synthetic graywater, containing vegetable oil, detergent, gelatin, and starch). The toxic effects of diesel fuel and several other components of oily wastewater (such as surfactants and a synthetic lubricant) on a naïve wastewater assemblage was also tested. In concentrations much higher than would be expected under normal shipboard conditions, we found no evidence of toxic effects of the bilgewater compounds tested. Thus, a combined shipboard bilgewater and sanitary wastewater system might be feasible.
Use of the 16S–23S ribosomal genes spacer region for the molecular typing of sphingomonads
Authors: Tokajian Sima , Al-Medawar Siba , Hashwa Fuad
Published: September 2008

The ability of sphingomonads in drinking water to cause community- and hospital-acquired opportunistic infections has raised the need to establish reproducible identification assays. In this study, a total of 129 isolates recovered from drinking water with yellow- to orange-pigmented colonies were distributed among 10 biotypes on the basis of colony morphology. Polymorphisms, based on the amplification and restriction digestion of the intergenic transcribed spacer (ITS) region within the 10 assigned biotypes and 18 ATCC reference strains, were used to investigate the ability of this approach to differentiate closely related sphingomonads. ITS size, which ranged between 400 and 1100 bp, did not vary enough among the different genera. However, 16 distinct banding patterns within the ATCC reference strains and 9 within the 10 biotypes were obtained through ITS restriction digestion, and the majority of the tested biotypes produced patterns similar to those generated by the ATCC strains. To our knowledge, this study is not only the first comprehensive record of the size of the ITS region in sphingomonads, it is also the first study that describes the use of ITS restriction digestion to subtype those isolates.
Novel extracellular proteolytic activity inPediococcus acidilacticiATCC 8042
Authors: Llorente-Bousquets Adriana , Pérez-Munguía Sandra , Farrés Amelia
Published: September 2008

Proteolytic systems are common in lactic acid bacteria, but there are few reports about proteases or peptidases in the genus Pediococcus . To evaluate the presence of these types of enzymes, Pediococcus acidilactici ATCC 8042 was cultured in MRS broth. Supernatants collected during the log phase showed proteolytic activity towards an elastin dispersion when assayed using a spectrophotometer. Zn2+showed a stimulatory effect, and the proteolytic activity reached its maximum when 200 mmol/L NaCl was included in the reaction buffer. On the other hand, activity was reduced when 5 mmol/L EDTA, 10 mmol/L phenylmethylsulfonyl fluoride, and 10 mmol/L 1,10-phenanthroline were used or when the sample was heat treated. Zymograms showed two different proteolytic bands when gelatin was used as a substrate (>200 and 107 kDa), but only the higher molecular mass band was detected when casein or elastin was used. The gelatinolytic activity was not detected with zymograms of the 107 kDa band, which was the one inactivated by heat treatment. The use of a renaturing SDS–PAGE gel with embedded Micrococcus lysodeikticus cells allowed for the detection of a band with peptidoglycan hydrolase activity migrating at about 110 kDa. This activity was lost when 10 mmol/L EDTA was added to the renaturing buffer. Therefore, Pediococcus showed at least three different extracellular enzymes that were produced during the logarithmic growth phase and acted on peptide substrates. Each showed different substrate specificity, ion requirements, and thermostability.
Variation of cell surface hydrophobicity and biofilm formation among genotypes ofCandida albicansandCandida dubliniensisunder antifungal treatment
Authors: Borecká-Melkusová Silvia , Bujdáková Helena
Published: September 2008

Candida infections are frequently associated with formation of biofilms on artificial medical devices. This work studied variation of cell surface hydrophobicity (CSH) and formation of biofilm in relation to Candida albicans and Candida dubliniensis genotypes and an effect of some conventional antifungal agents on both CSH and biofilm. The 50 isolates of C. albicans and C. dubliniensis were classified into genotypes A, B, C, and D, genotype D being exclusively represented by C. dubliniensis. No significant differences between CSH of genotypes A and B and B and C were observed with respect to cultivation temperature 25 or 37 °C. Candida dubliniensis showed increased CSH in comparison with other C. albicans genotypes (p < 0.001) regardless of temperature used. Using XTT reduction assay and dry masses, genotypes B and C showed reduced ability to form biofilm in comparison with genotype A (p < 0.05) and C. dubliniensis (p < 0.001). Fluconazole reduced biofilm in C. albicans genotypes A, B, and C (p < 0.05) but not CSH. The opposite effect was observed in C. dubliniensis. Voriconazole effectively reduced both biofilm formation and CSH in all tested genotypes of C. albicans and C. dubliniensis (p < 0.05).
Comparative study of the activity and kinetic properties of malate dehydrogenase and pyruvate decarboxylase fromCandida albicans,Malassezia pachydermatis, andSaccharomyces cerevisiae
Authors: Tylicki Adam , Ziolkowska Grazyna , Bolkun Aleksandra , Siemieniuk Magdalena , Czerniecki Jan , Nowakiewicz Agnieszka
Published: September 2008

Candida albicans and Malassezia pachydermatis cause human and animal infections of the skin and internal organs. We compare the properties of two enzymes, pyruvate decarboxylase (PDC) and malate dehydrogenase (MDH), from these species and from Saccharomyces cerevisiae cultivated under aerobic and anaerobic conditions to find differences between the enzymes that adapt pathogens for virulence and help us in searching for new antifungal agents. Malassezia pachydermatis did not show any growth under anaerobic conditions, as opposed to C. albicans and S. cerevisiae. Under aerobic conditions, C. albicans showed the highest growth rate. Malassezia pachydermatis, contrary to the others, did not show any PDC activity, simultaneously showing the highest MDH activity under aerobic conditions and a Kmvalue for oxaloacetate lower than S. cerevisiae. Candida albicans and S. cerevisiae showed a strong decrease in MDH activity under anaerobic conditions. Candida albicans shows four different isoforms of MDH, while M. pachydermatis and S. cerevisiae are characterized by two and three isoforms. Candida albicans shows about a twofold lower activity of PDC but, simultaneously, almost a threefold lower Kmvalue for pyruvate in comparison with S. cerevisiae. The PDC apoform share under aerobic conditions in C. albicans was 47%, while in S. cerevisiae was only 26%; under anaerobic conditions, the PDC apoform decreased to 12% and 8%, respectively. The properties of enzymes from C. albicans show its high metabolic flexibility (contrary to M. pachydermatis) and cause easy switching between fermentative and oxidative metabolism. This feature allows C. albicans to cause both surface and deep infections. We take into consideration the use of thiamin antimetabolites as antifungal factors that can affect both oxidative and fermentative metabolism.
Gene cloning, protein purification, and enzymatic properties of multicopper oxidase, fromKlebsiellasp. 601
Authors: Li Yang , Yin Jiao , Qu Guosheng , Lv Luchao , Li Yadong , Yang Sheng , Wang Xing-Guo
Published: September 2008

A gene encoding a putative multicopper oxidase (MCO) was cloned from the soil bacterium Klebsiella sp. 601 and its corresponding enzyme was overexpressed in an Escherichia coli strain. Klebsiella sp. 601 MCO is composed of 536 amino acids with a molecular mass of 58.2 kDa. Theoretical calculation gave a pI value of 6.11. The amino acid sequence of Klebsiella sp. 601 MCO is strongly homologous to that of E. coli CueO with a similarity of 90% and an identity of 78%. Unlike E. coli CueO, Klebsiella sp. 601 MCO contains an extra 20 amino acids close to its C-terminus. The enzyme was purified to homogeneity by Ni-affinity chromatography. The purified enzyme was capable of using DMP (2,6-dimethoxyphenol), ABTS (2,2′-azino-bis(3-ethylbenzthiazolinesulfonic acid)), and SGZ (syringaldazine) as substrates with an optimal pH of 8.0 for DMP, 3.0 for ABTS, and 7.0 for SGZ. Klebsiella sp. 601 MCO was quite stable at pH 7.0 in which its activity was constant for 25 h without any significant change. Kinetic studies gave Km, kcat, and kcat/Kmvalues of 0.49 mmol·L–1, 1.08 × 103s–1, and 2.23 × 103s–1·mmol–1·L, respectively, for DMP, 5.63 mmol·L–1, 6.64 × 103s–1, and 1.18 × 103s–1·mmol–1·L for ABTS, and 0.023 mmol·L–1, 11 s–1, and 4.68 × 102s–1·mmol–1·L for SGZ.