bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of in situ polychlorinated biphenyl elimination rate coefficients in the freshwater mussel biomonitor Elliptio complanata deployed in the huron–erie corridor, southeast Michigan, USA, and southwest Ontario, Canada
Authors: Raeside Ashley A. , O'Rourke Sarah M. , Drouillard Ken G.
Published: October 2008

Quantitative mussel biomonitoring studies often use laboratory-measured whole-body elimination rate coefficients (ktot) in conjunction with concentration data from field-deployed mussels to estimate bioavailable steady-state contaminant concentrations (Cm(ss)) in aquatic systems. However, the validity of applying laboratory ktot values to field-deployed mussels has not been verified. The present study quantified in situ ktot values by the common mussel biomonitor species Elliptio complanata for a group of performance reference compound polychlorinated biphenyl (PCB) congeners (International Union of Pure and Applied Chemistry 23, 61, 109, and 173) at 11 sites along the Lake Huron–Lake Erie corridor (southeast MI, USA, and southwest ON, Canada). Predictive site-specific ktot versus log KOW relationships were derived to estimate in situ ktot values for the bioaccumulated environmental PCB congeners, and the resultant steady-state concentration estimates were compared against values estimated using laboratory-derived ktot values. In situ ktot values were almost always faster (1.3–10-fold) than rate coefficients determined by laboratory studies, with a mean difference ± standard error of 3.89 ± 0.28-fold. Consequently, control adjusted steady-state concentrations of sum PCBs in the mussels were overestimated by factors ranging from 1.30 to 3.45 across sites when using laboratory-derived ktot values in place of in situ ktot values and a field deployment period of 90 d. This error was shown to increase with increasing congener hydrophobicity, as represented by their log KOW values, and when shorter field deployment times are performed. To more accurately predict the steady-state concentrations of environmentally accumulated PCBs in mussels, it is recommended that future quantitative biomonitoring studies employ the reference compound approach for measuring site-specific in situ ktot values.
In vitro thyroid hormone–disrupting activity in effluents and surface waters in Thailand
Authors: Ishihara Akinori , Rahman Farhana B. , Leelawatwattana Ladda , Prapunpoj Porntip , Yamauchi Kiyoshi
Published: October 2008

The thyroid hormone (TH)–disrupting activity of effluents and environmental water samples in Thailand was surveyed by three in vitro bioassays with different endpoints. These assays test the potency of competitive binding with the active form of TH, 3,3′,5-[125I]triiodo-l-thyronine (T3), to the plasma transport protein transthyretin (TTR) and TH receptor (TR; the TTR assay and TR assay, respectively) and the interference with the cellular T3-signaling pathway through TR-mediated luciferase gene activation (the luc assay). The TH-disrupting activity in water samples collected from paper manufacturing plants (PMPs), the canal Khlong U-Taphao, and a sewage-treatment plant (STP) was detected predominantly in the dichloromethane/methanol or methanol fractions of solid-phase extraction, suggesting a similar hydrophobic nature of the causative contaminants. The TR assay was relatively more sensitive than the TTR assay to the competitively potent contaminants. The luc assay indicated that the dichloromethane/methanol fractions of most water samples contained anti-T3-like activity. Our assays demonstrated that wastewater treatment effectively removed the TH-disrupting contaminants from wastewater in the PMP and the STP. The potencies for TH disruption at the three sampling points of the STP exhibited positive correlations among the three bioassays, whereas those from the canal and PMP water were not correlated among the three bioassays. Furthermore, the influent contaminants that were competitively potent in the TTR assay partially affected the luc assay. These bioassays are useful monitoring tools that give results relevant for evaluating the health of amphibian populations.
Sorption irreversibility of 1,4-dichlorobenzene in two natural organic matter–rich geosorbents
Authors: Sander Michael , Pignatello Joseph J.
Published: October 2008

Hysteresis, a frequently observed phenomenon in sorption studies, is inconsistent with the key assumption of sorption reversibility in most fate and bioavailability models. Therefore, a study of the underlying causes of hysteresis is essential. Carbon-radiolabeled 1,4-dichlorobenzene (DCB) isotope tracer exchange was carried out at select points along the isotherms of DCB in a brown coal and a peat soil, holding total DCB concentration constant. Tracer exchange was performed both in the forward (sorption) and reverse (desorption) directions at the bulk sorption points and in the desorption direction at the corresponding bulk desorption points. Bulk DCB isotherms showed concentration-dependent hysteresis. However, tracer reequilibration in all cases was consistent with free exchange between sorbed and aqueous-phase molecules. These results rule out common experimental artifacts and demonstrate that sorption of bulk DCB is truly hysteretic (i.e., irreversible). The differences in rates between bulk and tracer sorption and desorption are consistent with the coupling of bulk DCB diffusion to other processes that retard equilibration, which we assign to matrix swelling or shrinking. Hysteresis is attributed to matrix deformation—specifically, to inelastic expansion and creation of voids accommodating sorbate molecules in the matrix, which leads to enhanced affinity in the desorption step. Comparing the results to previous results for naphthalene in the coal, we find that irreversible effects are similar for DCB and naphthalene in the coal but differ for DCB between the two sorbents. An explanation based on the different physical properties of these sorbents is provided. Solid-phase extraction of equilibrated DCB with Tenax® revealed a highly desorption-resistant fraction. While too small to account for the observed hysteresis, this fraction may represent molecules that become trapped as the matrix collapses and simultaneously stiffens during abrupt desorption.
Influence of soil pH on the sorption of ionizable chemicals: Modeling advances
Authors: Franco Antonio , Fu Wenjing , Trapp Stefan
Published: October 2008

The soil–water distribution coefficient of ionizable chemicals (Kd) depends on the soil acidity, mainly because the pH governs speciation. Using pH-specific Kd values normalized to organic carbon (KOC) from the literature, a method was developed to estimate the KOC of monovalent organic acids and bases. The regression considers pH-dependent speciation and species-specific partition coefficients, calculated from the dissociation constant (pKa) and the octanol–water partition coefficient of the neutral molecule (log Pn). Probably because of the lower pH near the organic colloid–water interface, the optimal pH to model dissociation was lower than the bulk soil pH. The knowledge of the soil pH allows calculation of the fractions of neutral and ionic molecules in the system, thus improving the existing regression for acids. The same approach was not successful with bases, for which the impact of pH on the total sorption is contrasting. In fact, the shortcomings of the model assumptions affect the predictive power for acids and for bases differently. We evaluated accuracy and limitations of the regressions for their use in the environmental fate assessment of ionizable chemicals.
Assessment of larval deformities and selenium accumulation in northern pike (Esox lucius) and white sucker (Catostomus commersoni) exposed to metal mining effluent
Authors: Muscatello Jorgelina R. , Janz David M.
Published: October 2008

Uranium mining and milling operations in northern Saskatchewan (Canada) release effluents with elevated levels of certain trace metals and metalloids, including selenium. The goal of the present study was to evaluate the presence of selenium-induced deformities in northern pike (Esox lucius) and white sucker (Catostomus commersoni) larvae originating from adults collected downstream of a uranium mine. Eggs were fertilized in the field and incubated in the laboratory following a two-way (crossover) analysis-of-variance experimental design to discriminate effects from maternal transfer versus those from exposure to site water in the developing embryos. Selenium concentrations in northern pike and white sucker eggs (8.02 and 4.89 μg/g dry wt, respectively; mean ± standard error throughout) from the exposure site were approximately two- to threefold higher than reference (2.35 ± 0.20 and 1.94 ± 0.25 μg/g dry wt, respectively). Among all evaluated deformities (skeletal curvatures, craniofacial deformities, fin deformities, and edema), only edema in white sucker fry from the exposure site was slightly elevated (∼3%) compared to reference. The occurrence of edema, however, can be associated with factors other than selenium (e.g., other metals and organic compounds). Both fish species displayed strong linear relationships between the selenium concentrations in eggs and other tissues (muscle, liver, kidney, and bone), suggesting that selenium concentrations in eggs could be predicted from selenium concentrations in adult tissues. The lack of a clear, toxic response in the present study is in agreement with selenium thresholds for early life-stage deformities reported in other studies, with egg selenium concentrations in northern pike and white sucker collected at the exposure site being less than the 10 μg/g (dry wt) threshold associated with the presence of deformities.
Single and interactive effects of malathion, overwintered green frog tadpoles, and cyanobacteria on gray treefrog tadpoles
Authors: Mackey Mark J. , Boone Michelle D.
Published: October 2008

Amphibian population declines around the world are associated with invasive species, pesticides, pathogens, habitat destruction, or a combination of factors. Because contamination is widespread, it represents a relevant environmental stress that can affect the ability of organisms to deal with other factors present in the environment. We examined the effects of the insecticide malathion, larger tadpole competitors (green frogs, Rana clamitans), and a toxic cyanobacteria (Anabaena spp.) on tadpoles of Cope's gray treefrog (Hyla chrysoscelis) reared from hatching through metamorphosis in outdoor mesocosms. The response of mass at metamorphosis and time to metamorphosis was significantly affected by exposure to malathion and presence of overwintered green frog tadpoles. Malathion generally led to increased mass at metamorphosis, earlier time to metamorphosis, and increased activity during larval development. These results likely stem from short-term increases in periphyton associated with malathion exposure (although these effects were nonsignificant). Exposure of gray treefrogs to overwintered green frog tadpoles led to an earlier time to metamorphosis without differences in mass at metamorphosis and was associated with increased activity in gray treefrogs. Survival of gray treefrogs was significantly affected by an interaction of green frog and malathion, indicating nonadditive effects of these treatments. Exposure to cyanobacteria had a significant negative effect on green frogs but no effect on treefrogs. Malathion had the strongest effect on the community, but our results indicated that some factors can interact in ways not predicted by single factors alone.
Tributyltin sorption to marine sedimentary black carbon and to amended activated carbon
Authors: Brändli Rahel C. , Breedveld Gijsbert D. , Cornelissen Gerard
Published: October 2008

Under marine conditions, tributyltin (TBT) is speciated mainly as an uncharged hydroxyl complex (TBTOH) that is expected to have a similar fate to hydrophobic organic contaminants. Earlier studies indicated that for the later compounds, sorption to black carbon (BC) can be more than two orders of magnitude stronger than sorption to organic carbon, notably at low and environmentally relevant concentrations. The aim of the present study was to investigate the sorption strength of spiked TBT to a sediment and its BC isolate. It was observed that carbon-normalized sorption coefficients were in the same range for the sediment total organic carbon (TOC) and for its BC (log KTOC 5.05 L/kgTOC and log KBC 5.09 L/kgBC, respectively). This indicates that TBT does not sorb as strongly to BC as other hydrophobic organic contaminants. Activated carbon (AC), a strong man-made sorbent, has the potential to be used for in situ remediation of contaminated sediments and soils, in particular for polycyclic aromatic hydrocarbons and polychlorinated biphenyls. In the present study, both granular and powdered AC were found to strongly sorb TBT under marine conditions, with a log sorption coefficient of 6.8 L/kgcarbon. Tributyl- and dibutyltin concentrations in the pore water of a natively contaminated sediment were reduced by more than 70% on addition of 2% of powdered AC, whereas granular AC did not show a similar reduction. The results indicate that powdered AC might be a feasible remediation agent for sediments contaminated by organotins.
Disposition of perfluorinated acid isomers in sprague-dawley rats; Part 1: Single dose
Authors: Benskin Jonathan P. , De Silva Amila O. , Martin Leah J. , Arsenault Gilles , McCrindle Robert , Riddell Nicole , Mabury Scott A. , Martin Jonathan W.
Published: October 2008

Perfluorinated acids (PFAs) and their precursors (PFA-precursors) exist in the environment as linear and multiple branched isomers. These isomers are hypothesized to have different biological properties, but no isomer-specific data are currently available. The present study is the first in a two-part project examining PFA isomer-specific uptake, tissue distribution, and elimination in a rodent model. Seven male Sprague-Dawley rats were administered a single gavage dose of approximately 500 μg/kg body weight perfluorooctane sulfonate (C8F17SO3−, PFOS), perfluorooctanoic acid (C7F15CO2H, PFOA), and perfluorononanoic acid (C8F17CO2H, PFNA) and 30 μg/kg body weight perfluorohexane sulfonate (C6F13SO3−, PFHxS). Over the subsequent 38 d, urine, feces, and tail-vein blood samples were collected intermittently, while larger blood volumes and tissues were collected on days 3 and 38 for isomer analysis by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). For all PFAs, branched isomers generally had lower blood depuration half-lives than the corresponding linear isomer. The most remarkable exception was for the PFOS isomer containing an alpha-perfluoromethyl branch (1m-PFOS), which was threefold more persistent than linear PFOS, possibly due to steric shielding of the hydrophilic sulfonate moiety. For perfluoromonomethyl-branched isomers of PFOS, a structure–property relationship was observed whereby branching toward the sulfonate end of the perfluoroalkyl chain resulted in increased half-lives. For PFHxS, PFOA, and PFOS, preferential elimination of branched isomers occurred primarily via urine, whereas for PFNA preferential elimination of the isopropyl isomer occurred via both urine and feces. Changes in the blood isomer profiles over time and their inverse correlation to isomer elimination patterns in urine, feces, or both provided unequivocal evidence of significant isomer-specific biological handling. Source assignment based on PFA isomer profiles in biota must therefore be conducted with caution, because isomer profiles are unlikely to be conserved in biological samples.
Mercury demethylation in waterbird livers: Dose–response thresholds and differences among species
Authors: Eagles-Smith Collin A. , Ackerman Joshua T. , Yee Julie , Adelsbach Terrence L.
Published: October 2008

We assessed methylmercury (MeHg) demethylation in the livers of adults and chicks of four waterbird species that commonly breed in San Francisco Bay: American avocets, black-necked stilts, Caspian terns, and Forster's terns. In adults (all species combined), we found strong evidence for a threshold model where MeHg demethylation occurred above a hepatic total mercury concentration threshold of 8.51 ± 0.93 μg/g dry weight, and there was a strong decline in %MeHg values as total mercury (THg) concentrations increased above 8.51 μg/g dry weight. Conversely, there was no evidence for a demethylation threshold in chicks, and we found that %MeHg values declined linearly with increasing THg concentrations. For adults, we also found taxonomic differences in the demethylation responses, with avocets and stilts showing a higher demethylation rate than that of terns when concentrations exceeded the threshold, whereas terns had a lower demethylation threshold (7.48 ± 1.48 μg/g dry wt) than that of avocets and stilts (9.91 ± 1.29 μg/g dry wt). Finally, we assessed the role of selenium (Se) in the demethylation process. Selenium concentrations were positively correlated with inorganic Hg in livers of birds above the demethylation threshold but not below. This suggests that Se may act as a binding site for demethylated Hg and may reduce the potential for secondary toxicity. Our findings indicate that waterbirds demethylate mercury in their livers if exposure exceeds a threshold value and suggest that taxonomic differences in demethylation ability may be an important factor in evaluating species-specific risk to MeHg exposure. Further, we provide strong evidence for a threshold of approximately 8.5 μg/g dry weight of THg in the liver where demethylation is initiated.
Liver microsomes and S9 from rainbow trout (Oncorhynchus mykiss): Comparison of basal-level enzyme activities with rat and determination of xenobiotic intrinsic clearance in support of bioaccumulation assessment
Authors: Han Xing , Nabb Diane L. , Yang Ching-Hui , Snajdr Suzanne I. , Mingoia Robert T.
Published: October 2008

Metabolism plays an important role in bioaccumulation of xenobiotics in fish. The applicability of trout liver microsomes and S9 fraction in bioaccumulation assessment of xenobiotics in fish was investigated in the present study. Basal-level activities of 7-ethoxyresorufin-O-dealkylase, testosterone 6β-hydroxylase, glutathione-S-transferase, and uridine 5′-diphospho-glucuronosyl-transferase in trout liver microsomes and S9 were significantly lower than those in rat liver microsomes and S9. The in vitro–to–in vivo scaling factors, which are the values of liver microsomal and S9 protein contents per unit weight of trout liver, were determined to be 38.4 ±5.1 (mean ± standard deviation throughout) and 95.9 ±11.9 mg/g, respectively. Intrinsic clearance (CLint) values for a number of reference compounds obtained from trout liver S9 were lower than those from trout liver microsomes. After correction with the scaling factors, trout liver microsomes and S9 provided equivalent prediction of trout hepatic clearance (CLH) using the well-stirred liver model, but their CLH values were significantly lower than those obtained from freshly isolated trout hepatocytes. Consequently, trout liver microsomes and S9 showed poorer prediction of the bioconcentration factors of the reference compounds compared with trout hepatocytes. Unit conversion revealed that CLint values obtained from trout liver microsomes and S9 were 6.3 to 22.4% of those from trout hepatocytes, which explained, to a large extent, the differences in their CLH and bioconcentration factor prediction.
Oil dispersion increases the apparent bioavailability and toxicity of diesel to rainbow trout (Oncorhynchus mykiss)
Authors: Schein Allison , Scott Jason A. , Mos Lizzy , Hodson Peter V.
Published: October 2008

Diesel is a complex mixture containing polycyclic aromatic hydrocarbons, which persist after a spill, pass readily from water into tissues, and are toxic to early life stages of fish. The bioavailability and chronic toxicity of hydrocarbons dissolved into water from floating diesel (water-accommodated fraction) and chemically dispersed diesel (chemically enhanced water-accommodated fraction) were measured by the extent of ethoxyresorufin-O-deethylase (EROD) induction in juvenile rainbow trout (Oncorhynchus mykiss) and by the severity of blue sac disease in embryos. The water-accommodated fraction of floating diesel was virtually nontoxic to embryos at nominal concentrations up to 1,000 mg/L, causing only small weight changes. Liver EROD induction in juvenile trout was only observed at the highest nominal water-accommodated fraction concentration (10,000 mg/L). Chemical dispersion increased the bioavailability and toxicity of diesel to trout by 100-fold. Diesel chemically enhanced water-accommodated fraction induced EROD activity, caused blue sac disease, and impaired development and growth of embryonic trout at nominal concentrations as low as 10 mg/L; 88% mortality occurred at 100 mg/L. However, when total hydrocarbon concentrations were measured, differences between dispersed and undispersed diesel disappeared, with a median lethal concentration of 8 mg/L of total hydrocarbons and sublethal median effective concentrations ranging from 1.3 to 6.1 mg/L. Dispersion of diesel by high-energy mechanical mixing was recently reported to cause acute lethality to juvenile trout between 40 and 200 mg/L. Therefore, dispersion of oil by any means increases the bioavailability and apparent toxicity of diesel to fish embryos without changing the toxicity of its components. Nevertheless, in an actual spill, dispersion of diesel increases the effects of oil on fish populations.
A nonlethal microsampling technique to monitor the effects of mercury on wild bird eggs
Authors: Stebbins Katherine R. , Klimstra Jon D. , Eagles-Smith Collin A. , Ackerman Joshua T. , Heinz Gary H.
Published: October 2008

Methylmercury is the predominant chemical form of mercury reported in the eggs of wild birds, and the embryo is the most sensitive life stage to methylmercury toxicity. Protective guidelines have been based mainly on captive-breeding studies with chickens (Gallus gallus), mallards (Anas platyrhynchos), and ring-necked pheasants (Phasianus colchicus) or on field studies where whole eggs were collected and analyzed and the effects of the mercury were measured based on the reproductive success of the remaining eggs. However, both of these methods have limitations. As an alternative, we developed a technique that involves extracting a small sample of albumen from a live egg, sealing the egg, returning the egg to its nest to be naturally incubated by the parents, and then relating the hatching success of this microsampled egg to its mercury concentration. After first developing this technique in the laboratory using chicken and mallard eggs, we selected the laughing gull (Larus atricilla) and black-necked stilt (Himantopus mexicanus) as test subjects in the field. We found that 92% of the microsampled laughing gull eggs met our reproductive endpoint of survival to the beginning of hatching compared to 100% for the paired control eggs within the same nests. Microsampled black-necked stilt eggs exhibited 100% hatching success compared to 93% for the paired control eggs. Our results indicate that microsampling is an effective tool for nonlethally sampling mercury concentrations in eggs and, as such, can be used for monitoring sensitive species, as well as for improving studies that examine the effects of mercury on avian reproduction.
Genotoxic effect of 2,4,6-trichlorophenol onP53gene in zebrafish liver
Authors: Yin Daqiang , Zhu Hankai , Hu Ping , Zhao Qingshun
Published: October 2008

Trichlorophenol (2,4,6-trichlorophenol [TCP]), a probable human carcinogen, is widely present in the environment. Employing denaturing high-performance liquid chromatography and DNA sequencing analyses, we demonstrated that 10-d exposure of zebrafish to TCP at 5 μg/L resulted in elevated point mutations of p53 gene in the liver genome. The result suggests that TCP might be involved in carcinogenesis by inducing point mutations in the somatic genome.
In vitro study of DNA damage induced by acid orange 52 and its biodegradation derivatives
Authors: Mansour Hedi Ben , Barillier Daniel , Corroler David , Ghedira Kamel , Chekir-Ghedira Leila , Mosrati Ridha
Published: October 2008

Mutagenicity of acid orange 52 (AO52) and its degradation products by Pseudomonas putida mt-2 was evaluated with the use of Salmonella Typhimurium TA102 and TA104 with and without the metabolic activation system (S9). No mutagenicity was observed in the absence of S9 and in the presence of S9 for biodegradation under shaking conditions, but it increased significantly in the presence of S9 after biodegradation under static conditions. In addition, the ability of tested compounds to induce DNA damage in vitro was evaluated with the DNA strand scission assay. The toxicity generated by the pure azo dye and the corresponding azoreduction products (4-aminobenzenesulfonic acid and N,N′-dimethyl-p-phenylenediamine) were compared. We suggest that the mutagenicity mechanism of these molecules occurs through free radical generation processes. In this study, we demonstrate that P. putida mt-2 incubated under aerobic conditions undergoes catabolism that enables it to degrade AO52 completely and, especially, to detoxify the dye mixtures.
Plant biotechnology for deeper understanding, wider use and further development of agricultural and horticultural crops
Authors: ELOMAA P. , JOENSUU J.J. , KORPELAINEN H.
Published: October 2008

Plants bind solar energy to organic matter via photosynthesis and assimilation of carbon dioxide from the atmosphere and comprise the major source of nutrition and bioenergy. Plant biotechnology contributes to solution of important constraints in food and feed production and creates new technologies and applications for the sustainable use of plant resources. Genome-wide approaches such as massive parallel sequencing and microarrays to study gene expression, molecular markers for selection of important traits in breeding, characterization of genetic diversity with the aforementioned approaches, and somatic hybridization and genetic transformation are important tools in plant biotechnology. In this paper, studies carried out on enhanced resistance to viruses and tolerance of cold stress in potato, genetic modification of flower pigmentation and morphology in gerbera, production of edible vaccines in transgenic barley seeds, and expression of heterologous proteins for pharmaceutical purposes from vector viruses were chosen to exemplify the general utility of biotechnological approaches and also how plant biotechnology research has developed on cultivated plants at University of Helsinki. The studies reveal cellular and genetic mechanisms and provide scientific information that can be used for widening the uses of crop plants. They can also be used to detect any putative risks associated with the use of the biotechnological application in agriculture and horticulture and to develop practises which reduce any inadvertent negative consequences that plant production may have to the environment.;
Properties and cleanability of new and traditional agricultural surface materials
Authors: MÄÄTTÄ J. , KYMÄLÄINEN H-R. , HELLSTEDT M.
Published: October 2008

The aim of the present study was to evaluate new and traditional surface materials for use in cattle barns. The evaluated concrete materials had different compositions and included different additives and coatings. Contact angle meter, optical profilometry and scanning electron microscopy SEM were used for characterization of surface properties. Radiochemical methods and a biochemical adenosine triphosphate ATP method were used to determine cleanability. A specific methodological aim was to examine the correlations between these determination methods. A statistically significant difference was observed between contact angles of non-coated concretes, coated concretes and joint materials. In general, coatings smoothened surfaces and the joint materials were the roughest surfaces, as illustrated by profilometry and SEM. On the basis of the radiochemical determination methods, coatings improved the cleanability of concrete. An epoxy joint material was cleaned efficiently from the oil model soil and from the labelled feed soil when compared to the two cement-based joint materials. According to the results of the biochemical ATP method the manure test soil was cleaned better from a concrete including inorganic sealant than from the other materials examined. The cleanability results of oil model soil used in the radiochemical method correlated with the results of the test feed soil used in the biochemical ATP method. Both determination methods of cleanability appeared to be suitable for examining the cleanability of surfaces soiled with agricultural soils. Only the radiochemical determination gives detailed quantitative results, but it can be used only in laboratory studies. The results of this laboratory study will be used for selecting materials for a pilot study in a cattle barn.;
Sensitivity of soil phosphorus tests in predicting the potential risk of phosphorus loss from pasture soil
Authors: SOINNE H. , SAARIJÄRVI K. , KARPPINEN M.
Published: October 2008

The objective of this study was to examine the effects of urine and dung additions on the phosphorus (P) chemistry of pasture land and to compare the sensitivity of two soil extraction methods in assessing the P-loading risk. In a field experiment, urine and dung were added to soil in amounts corresponding to single excrement portions and the soil samples, taken at certain intervals, were analysed for pHH2O, acid ammonium acetate extractable P (PAc) and water extractable total P (TPw), and molybdate reactive P (MRPw). Urine additions immediately increased soil pH and MRPw, but no such response was observed in PAc extraction due to the low pH (4.65) of the extractant enhancing the resorption of P. The PAc responded to the dunginduced increase in soil total P similarly as did Pw, which suggests that both tests can serve to detect areas of high P concentration. However, water extraction was a more sensitive method for estimating short-term changes in P solubility. In pasture soils, the risk of P loss increases as a result of the interaction of urination and high P concentration in the topsoil resulting from continuous dung excretion.;
Spring Cereals: From Dynamic Ideotypes to Cultivars in Northern Latitudes
Authors: MÄKELÄ P. , MUURINEN S. , PELTONEN-SAINIO P.
Published: October 2008

The ideotype of a crop is a model of a plant community where all necessary and beneficial traits for crop performance in a particular environment are combined. It is important to consider the environment when developing an ideotype since climatic, edaphic and agronomic features of the target region have a major role in determining crop performance. New technologies, high yielding cultivars, irrigation and water management, plant protection materials and more skilful farm management practices have increased yields and yield potentials on cereals in Finland as in many other countries. In this paper we aim to summarize traits which would be useful from the farmers perspective. The most important trait is increased early vigour of spring cereals, including faster rate of early development and increased leaf area to improve both the resource capture of the canopy and water use efficiency. Introduction of dwarfing genes would improve lodging resistance and harvest index due to improved partitioning of dry matter into grains whereas longer coleoptiles would improve emergence and seedling establishment. Improved ability of crops to utilize stem reserves during grain filling would increase resistance against environmental stresses. All of these traits would also increase the competitive ability of the plant against weeds as well as competition within the crop canopy and are already available from non-adapted germplasm of the various spring cereal species.;
Impact of selenium enrichment on seed potato tubers
Authors: TURAKAINEN M. , HARTIKAINEN H. , SARJALA T.
Published: October 2008

The aim of this study was to investigate the effect of Se enrichment on the growth of sprouts and growth vigour of seed potatoes (Solanum tuberosum L.) stored for 2 to 8 months. Our results showed that Se did not affect the duration of dormancy. At the high addition levels (0.075 and 0.9 mg kg-1 quartz sand), Se had some positive effects on the growth of sprouts. The peak sprouting capacity was reached after 8 months of storage. The highest Se enrichment of tubers had some positive effect on the free putrescine content in sprouts. However, the better growth of sprouts was not consistent with the growth vigour of the seed tubers and yield produced. Selenium had no significant effect on the malondialdehyde (MDA) or on the concentration of soluble sugars and starch. No significant effect of added Se on the early growth, stem and tuber numbers and yield parameters was observed. Irrespective of the level of Se added, the highest yield was harvested from plants produced with seed tubers stored for 6 months. Our results indicate that Se had some positive effects on the growth of sprouts, but it had no consistent effect on the growth vigour of seed tubers.;
Comparison of energy and greenhouse gas balances of biogas with other transport biofuel options based on domestic agricultural biomass in Finland
Authors: TUOMISTO H. L. , HELENIUS J.
Published: October 2008

Biofuels have been promoted as a way to reduce greenhouse gas (GHG) emissions, but it is questionable whether they indeed do so. The study compared energy and GHG balances of transport biofuels produced in Finnish conditions. Energy and GHG balances were calculated from a life cycle perspective for biogas when timothy-clover and reed canary grass silages and green manure of an organic farm were used as a raw material. The results were compared with published data on barley-based ethanol, rape methyl ester (biodiesel) and biowaste-based biogas. The energy input for biogas was 2237% of the output depending on the raw material. The GHG emissions from field-based biogas were 2136% of emissions from fossil-based fuels. The largest energy input was used in the processing of the biofuels while most of the greenhouse gases were emitted during farming. The GHG emissions of the field-based biogas were emitted mainly from fuels of farming machinery, nitrous oxide (N2O) emissions of the soil and the production of ensiling additives. The energy efficiency was most sensitive to the methane yield, and GHG emissions to the N2O emissions. Biogas had clearly lower energy input and GHG emissions per unit energy output than domestic barley-based ethanol and biodiesel.;
Marital Status and Fertility of 185 Male Renal Transplant Recipients in China
Authors: Xu Long‐Gen , Wang Hong‐Wei , Peng Wang‐Ling , Jin Li‐Ming , Zhu Xiao‐Feng , Xu Hui‐Ming , Song Qi‐Zhe , Xu Biao , Ding Xian‐Fan
Published: October 2008

ABSTRACT: A questionnaire was designed to assess the effects of renal transplantation in men of reproductive age on marital status and fertility. The study sought to correlate recipients' marital status and fertility with the health of the recipients after the transplantation, the health of children they fathered after the procedure, and the functioning of the transplanted kidney. Male recipients (n = 243) who were single and of reproductive age before renal transplantation were selected from 2007 recipients of a renal transplant recorded in the authors' hospitals in China. Of the 243 surveyed, 185 completed the questionnaire and participated in follow‐up in the clinic or by telephone. Their marital status and fertility were investigated. Of the 185 recipients, 69 got married 12–88 months (mean, 32.19 ± 14.30 months) after renal transplantation, and 62 of 69 couples were actively attempting to become pregnant. Fifty‐three patients fathered 54 children, including 1 pair of twins, 9–72 months (mean, 25.81 ± 15.33 months) after marriage. The birth weights of the newborns ranged from 2500 to 4600 g (mean, 3395 ± 456.80 g). These children developed well. Nine patients did not father any children, and 3 of these 9 cases were attributable to infertility in the wife. Seven patients were using contraceptives. Three recipients suffered from chronic graft rejection and resumed hemodialysis 2–11 years after they fathered children. In addition, 2 patients died after fathering 1 child: 1 from dysfunction of the transplanted kidney 9 years after birth of his child, and another in an accident 1 year after his child's birth. Our findings suggest that, like men without renal transplants, male recipients of renal transplants can get married and father children, and the transplantation procedure appears to have no significant effect on the children fathered afterwards, on the recipients' health, or on the functioning of the transplanted kidney. It is very important to indicate that, in addition to needing contraception if they do not conceive, male renal transplant recipients should expect fertility rates that are similar to those of the general population.
Curcumin Blocks the Activation of Androgen and Interlukin‐6 on Prostate‐Specific Antigen Expression in Human Prostatic Carcinoma Cells
Authors: Tsui Ke‐Hung , Feng Tsui‐Hsia , Lin Chang‐Mei , Chang Phei‐Lang , Juang Horng‐Heng
Published: October 2008

ABSTRACT: Curcumin, a naturally occurring compound, exhibits anticancer chemopreventive effects. We evaluated the effects and mechanisms of curcumin on the gene expression of prostate‐specific antigen (PSA) in human androgen‐sensitive prostatic carcinoma cells. LNCaP cells were used to determine the effect of curcumin on PSA expression. Quantitative PSA expression was assessed by reverse transcription polymerase chain reaction (RT‐PCR), enzyme‐linked immunosorbent assay (ELISA), and immunoblot assay. The modulation of androgen, interlukin‐6 (IL‐6), and prostate‐derived Ets factor (PDEF) on the PSA gene was identified by transient gene expression assay with the use of a PSA reporter vector. The effect of curcumin on the activity of androgen receptors was evaluated by electrophoretic mobility shift assay (EMSA). Immunoblot assays, RT‐PCR, and ELISA indicated that curcumin treatments blocked the stimulation of methyltrienolone (R1881) and IL‐6 on PSA gene expression in LNCaP cells. The effects of curcumin appear to be mediated via the androgen response element of PSA gene. Results from immunoblot assay and EMSA revealed the modulation of curcumin on the expression of androgen receptor and androgen receptor binding activity on androgen response element of PSA gene. Although overexpression of PDEF dramatically enhanced PSA gene expression, the results of immunoblot assays and transient reporter assays indicated that curcumin treatments did not affect the gene expression of PDEF. Curcumin inhibits R1881‐ and IL‐6‐mediated PSA gene expression in LNCaP cells through down‐regulation of the expression and activity of androgen receptors.
Retarded Differentiation of Leydig Cells and Increased Apoptosis of Germ Cells in the Initial Round of Spermatogenesis of Rats With Lethal Dwarf and Epilepsy (lde/lde) Phenotypes
Authors: Takenaka Motoo , Yagi Mio , Amakasu Kohei , Suzuki Katsushi , Suzuki Hiroetsu
Published: October 2008

ABSTRACT: The lde/lde rats show a severe dwarf phenotype with early postnatal lethality and a high incidence of epileptic seizure. Seizures are first detected in this model between 16 and 63 days of age, and mostly begin as wild running and progress to generalized tonic‐clonic convulsions. Because our histological examination detected many extracellular vacuoles in the hippocampus and amygdaloid bodies of these animals at 28 days of age, these pathological alterations may be related to the epileptogenesis in lde/lde rats. In addition to these defects, male lde/lde rats have apparently smaller testes with reduced number of germ cells and poorly matured adult‐type Leydig cells in comparison with wild‐type controls. In the present study, we performed anatomical, histological, and endocrinologic examinations to characterize the testicular phenotype of lde/lde rats at 21, 28, 35, and 56 days of age. Male lde/lde rats showed severely retarded growth of the testes and accessory sex organs. Their seminiferous tubules were significantly smaller and contained markedly fewer germ cells at all time points examined as compared with controls. Significantly fewer Sertoli cells at 21 and 28 days of age, markedly decreased spermatocyte number at 28 days of age, and delayed appearance of spermatids at 56 days of age were observed in the testes of lde/lde rats. More TUNEL (T&T‐mediated duTP‐biotin nick‐end labeling)‐positive cells were detected in lde/lde seminiferous tubules, and the largest number of apoptotic cells was recorded at 28 days of age. The increases in 3β‐hydroxysteroid dehydrogenase‐positive adult‐type Leydig cells and 11β‐hydroxysteroid dehydrogenase‐positive mature adult‐type Leydig cells were also severely retarded in the testes of lde/lde rats. Consistent with these defects, significantly lower plasma follicle‐stimulating hormone (FSH), luteinizing hormone (LH), and testosterone concentrations were detected in lde/lde males at 28 days of age, and weak immunostaining for FSH and smaller cytoplasm of LH‐positive cells were detected in the anterior pituitary lobes of lde/lde males. Despite a normal level of plasma LH after 35 days of age, a significantly lower level of plasma testosterone was detected at 56 days of age. These results indicate that the normal lde allele is related to prepubertal elevations of gonadotropins and normal development of adult‐type Leydig cells. Because lde/lde rats experience epileptic seizures during the period when the hypothalamus‐pituitary‐testicular axis is established, lde/lde rats would be useful as a model for reproductive disorder with pediatric epilepsy.
Reference Ranges for Serum Dehydroepiandrosterone Sulfate and Testosterone in Adult Men
Authors: Friedrich Nele , Völzke Henry , Rosskopf Dieter , Steveling Antje , Krebs Alexander , Nauck Matthias , Wallaschofski Henri
Published: October 2008

ABSTRACT:Dehydroepiandrosterone (DHEA) is the main adrenal androgen, which mostly exists in a sulfated version (DHEAS). Both DHEA and DHEAS are metabolic intermediates in the biosynthesis of the male sex hormone testosterone. In men, testosterone is involved in the regulation of fertility, libido, and muscle mass and is valuable for the assessment of gonadal, adrenal, and pituitary function and for the diagnosis of hypogonadism. The objective of the present study was to calculate age‐specific reference ranges for serum DHEAS and serum testosterone using 1) linear regression and the mean ± 1.96 standard deviation concept and 2) quantile regression. From the cross‐sectional Study of Health in Pomerania a total of 1078 men aged 20–79 years were included in the analyses. Serum DHEAS and testosterone levels were quantified using IMMULITE 2500 immunoassays. Linear and quantile regression were performed to calculate age‐specific reference ranges. Both statistical methods generated different results: The reference ranges based on linear regression identified 17 men (1.6%) with DHEAS levels and 45 men (4.2%) with serum testosterone levels outside the reference range. Using quantile regression, 54 men (5.0%) and 50 men (4.6%) with serum DHEAS and testosterone levels outside the range were detected, respectively. The present study established age‐specific reference ranges for serum DHEAS and testosterone levels for men. Quantile regression should be preferred to calculate reference ranges; a better concordance with original data is possible because no distribution assumption is required and the robustness against outliers is given.
Algorithmic Animation in Education—Review of Academic Experience
Authors: Esponda-Argüero Margarita
Published: October 2008

This article is a review of the pedagogical experience obtained with systems for algorithmic animation. Algorithms consist of a sequence of operations whose effect on data structures can be visualized using a computer. Students learn algorithms by stepping the animation through the different individual operations, possibly reversing their effect. Algorithmic animation seems to improve the student's understanding of algorithms, but mainly when they can become active participants, not just spectators. Students who write their own algorithmic animations are more engaged and can profit more from them. At the end of this article, we extract some consequences for the development of future algorithmic animation systems.
Using Social Network Analysis to Understand Sense of Community in an Online Learning Environment
Authors: Shen Demei , Nuankhieo Piyanan , Huang Xinxin , Amelung Christopher , Laffey James
Published: October 2008

This study uses social network analysis (SNA) in an innovative way to describe interaction and explain how interaction influences sense of community of students in online learning environments. The findings reveal differences on sense of community between two similarly structured online courses, and show unique interaction patterns for students in the two courses. These results should prove to be interesting to researchers of online learning both on a theoretical and methodological basis.
Predictors of Foreign Language Reading Comprehension in a Hypermedia Reading Environment
Authors: Akbulut Yavuz
Published: October 2008

This study investigated factors affecting second/foreign language (L2) reading comprehension in a hypermedia environment within the theoretical framework of dual coding and cognitive load theories, and interactive models of L2 reading. The independent variables were reading ability, topic interest, prior topical knowledge, and the number of times participants accessed annotations. The dependent variable of interest was reading comprehension measured through a recall test. The participants were 54 senior foreign language teaching students at a state university in Turkey. The participants were given a hypertext to read for general comprehension and were told that they would be required to write down everything they remembered at the end of reading. The text was annotated with multiple forms of media: text, graphics, audio, and video. Annotations provided information both at the word level (i.e., definitions of words) and topic level (i.e., extra information about the topic). A multiple regression analysis with reading comprehension as the criterion and the independent variables mentioned above as the predictors served to reveal whether a relationship existed between the potential predictor and outcome variables. Findings indicated that topic interest and annotation look up were important variables contributing to reading comprehension in a hypermedia environment. It was also found that videos and textual information were the most useful types of annotations. It was suggested that hypermedia environments accommodated for most types of learning styles. It was also suggested that providing extra topical information through annotations compensated for the lack of prior knowledge.
Relationships between Computer Self-Efficacy, Technology, Attitudes and Anxiety: Development of the Computer Technology Use Scale (CTUS)
Authors: Conrad Agatha M. , Munro Don
Published: October 2008

Two studies are reported which describe the development and evaluation of a new instrument, the Computer Technology Use Scale (CTUS), comprising three domains: computer self-efficacy, attitudes to technology, and technology related anxiety. Study 1 describes the development of the instrument and explores its factor structure. Study 2 used confirmatory factor analysis to evaluate the stability of the factors identified and to examine relationships between computer self-efficacy, attitudes, and anxiety. There were 479 (Study 1) and 352 (Study 2) University—recruited subjects who volunteered for the project. The initial five factor solution of the CTUS scale was confirmed which include the following factors: computer efficacy, technology related anxiety, complexity, positive attitudes, and negative attitudes. Computer efficacy was positively related to positive attitudes and negatively related to other factors. The relationship between the factors is discussed.