bluuebunny/crossref_metadata_2025 huggingface dataset:
Exoribonuclease R in Mycoplasma genitalium can carry out both RNA processing and degradative functions and is sensitive to RNA ribose methylation
Authors: Lalonde Maureen S. , Zuo Yuhong , Zhang Jianwei , Gong Xin , Wu Shaohui , Malhotra Arun , Li Zhongwei
Published: September 2007

Mycoplasma genitalium, a small bacterium having minimal genome size, has only one identified exoribonuclease, RNase R (MgR). We have purified MgR to homogeneity, and compared its RNA degradative properties to those of its Escherichia coli homologs RNase R (EcR) and RNase II (EcII). MgR is active on a number of substrates including oligoribonucleotides, poly(A), rRNA, and precursors to tRNA. Unlike EcR, which degrades rRNA and pre-tRNA without formation of intermediate products, MgR appears sensitive to certain RNA structural features and forms specific products from these stable RNA substrates. The 3′-ends of two MgR degradation products of 23S rRNA were mapped by RT-PCR to positions 2499 and 2553, each being 1 nucleotide downstream of a 2′-O-methylation site. The sensitivity of MgR to ribose methylation is further demonstrated by the degradation patterns of 16S rRNA and a synthetic methylated oligoribonucleotide. Remarkably, MgR removes the 3′-trailer sequence from a pre-tRNA, generating product with the mature 3′-end more efficiently than EcII does. In contrast, EcR degrades this pre-tRNA without the formation of specific products. Our results suggest that MgR shares some properties of both EcR and EcII and can carry out a broad range of RNA processing and degradative functions.
RluD, a highly conserved pseudouridine synthase, modifies 50S subunits more specifically and efficiently than free 23S rRNA
Authors: Vaidyanathan Pavanapuresan P. , Deutscher Murray P. , Malhotra Arun
Published: September 2007

Pseudouridine modifications in helix 69 (H69) of 23S ribosomal RNA are highly conserved among all organisms. H69 associates with helix 44 of 16S rRNA to form bridge B2a, which plays a vital role in bridging the two ribosomal subunits and stabilizing the ribosome. The three pseudouridines in H69 were shown earlier to play an important role in 50S subunit assembly and in its association with the 30S subunit. In Escherichia coli, these three modifications are made by the pseudouridine synthase, RluD. Previous work showed that RluD is required for normal ribosomal assembly and function, and that it is the only pseudouridine synthase required for normal growth in E. coli. Here, we show that RluD is far more efficient in modifying H69 in structured 50S subunits, compared to free or synthetic 23S rRNA. Based on this observation, we suggest that pseudouridine modifications in H69 are made late in the assembly of 23S rRNA into mature 50S subunits. This is the first reported observation of a pseudouridine synthase being able to modify a highly structured ribonucleoprotein particle, and it may be an important late step in the maturation of 50S ribosomal subunits.
Gene silencing mechanisms mediated by Aubergine–piRNA complexes in Drosophila male gonad
Authors: Nishida Kazumichi M. , Saito Kuniaki , Mori Tomoko , Kawamura Yoshinori , Nagami-Okada Tomoko , Inagaki Sachi , Siomi Haruhiko , Siomi Mikiko C.
Published: September 2007

Genetic studies have shown that Aubergine (Aub), one of the Piwi subfamily of Argonautes in Drosophila, is essential for germ cell formation and maintaining fertility. aub mutations lead to the accumulation of retrotransposons in ovaries and testes, and Stellate transcripts in testes. Aub in ovaries associates with a variety of Piwi-interacting RNAs (piRNAs) derived from repetitive intergenic elements including retrotransposons. Here we found that Aub in testes also associates with various kinds of piRNAs. Although in ovaries Aub-associated piRNA populations are quite diverse, piRNAs with Aub in testes show a strong bias. The most abundant piRNAs were those corresponding to antisense transcripts of Suppressor of Stellate [Su(Ste)] genes known to be involved in Stellate gene silencing. The second most abundant class was made up of those from chromosome X and showed strong complementarity to vasa transcripts. Immunopurified Aub–piRNA complexes from testes displayed activity in cleaving target RNA containing sequences complementary to Stellate and vasa transcripts. These results provide the first biochemical insights into gene silencing mechanisms mediated by Aub and piRNAs in fly testes.
Repertoires of paedophilia: Conflicting descriptions of adult-child sexual relationships in the investigative interview
Authors: Benneworth Kelly
Published: September 2007

A review of the literature revealed that adult-child sexual relationships are often described in terms of personal bonds and emotions in pro-paedophile propaganda and the accounts of convicted paedophiles. On the other hand, in the investigative interview police officers must encourage offenders to be precise in their accounts and describe sexual contact. Research has not determined whether these two conflicting approaches to the description of paedophilia are observable in police interviews and, if so, considered the implications for the criminal investigation. Eleven audiotaped police interviews with paedophiles conducted at a Child Protection Unit in 2000 were transcribed. A corpus of 20 physical’ references to sexual activity and bodily contact and 42 ‘emotional’ words involving feelings and relationships were identified and the incidence of the terms was quantified. Content analysis confirmed that police officers and paedophiles do describe adult-child sexual relationships differently in the investigative interview. The police used the ‘physical’ repertoire more frequently, while the suspects exhibited a preference for the ‘emotional’ repertoire (?2 = 125.518; df = 1; p<0.01). The suspects also used euphemistic and colloquial language more frequently than the police (?2= 65.964; df = 1; p<0.01).The practical implications of the study and recommendations for future research are outlined.
Suspects' resistance to constraining and coercive questioning strategies in the police interview
Authors: Newbury Phillip , Johnson Alison
Published: September 2007

Discussions of institutional discourse have frequently focused on asymmetrical power relationships between participants. However, although power and control have been the focus of much critical writing in discourse studies, far less attention has been paid to resistance as an interactional resource. This article uses a qualitative Hallidayan approach to explore questions and responses in an interview between police and Dr Harold Shipman, focusing on resistance strategies employed by him in relation to the institutionally more powerful interviewer. The interviewee actively resists powerful questions through contest, correction, avoidance and refusal, whilst negotiating the costs of resistance, such as challenge to the consensus of control and flouting of the Cooperative Principle (Grice 1975) that would result in presenting an uncooperative speaker. The interview is seen as a site of resistant struggle, where agreement and disagreement are actively negotiated and where each participant attempts to produce different goals and opposing roles.
Idenfication of voices in shouting
Authors: Blatchford Helen , Foulkes Paul
Published: September 2007

Two experiments were carried out to assess the ability of lay listeners to identify familiar voices from shouted samples. The experiments were conducted after a murder case in which a witness claimed to recognise the voice of a masked gunman based on two shouted words: get him! Our experiments were designed to explore the extent to which a listener can identify a known voice from a shouted sample, and also whether a two word sample is sufficient for identification. Recordings were obtained from a group of nine females who formed a close social network, plus six foils. Two shouted utterances were extracted for listening tests: for Test 1, ‘get him!’, and for Test 2, ‘face down on the ground and hands behind your back now!’ Thirteen listeners from the same social network participated in the tests. Listeners correctly identified familiar speakers in 52% of cases in Test 1 and 81% in Test 2. There was considerable variation in results across listeners, and also with respect to individual voices. The results suggest that recognition of shouted voices is far from perfect, even in closed tests carried out among a close network. The variability in performance emphasises the need to subject a witness’s ability to identify a voice in a forensic case to formal testing wherever this is feasible.
R v John Samuel Humble: The Yorkshire Ripper Hoaxer Trial
Authors: French Peter , Harrison Philip , Lewis Jack Windsor
Published: September 2007

Between October 1975 and November 1980 13 murders were committed by the same man, Peter Sutcliffe, in the northern English towns and cities of Leeds, Bradford, Huddersfield and Manchester. The killings, which became known as the ‘Yorkshire Ripper’ murders, were of women, aged between 16 and 47, most of whom were prostitutes. The astonishingly long time for which the killer remained unidentified and active was undoubtedly at least in part attributable to the activities of a hoaxer. Between March 1978 and June 1979 the hoaxer sent three letters, one to the Daily Mirror newspaper, and two to the senior police officer investigating the case, to whom he also sent a tape recorded message. The originator of the letters and recording claimed to be the Yorkshire Ripper and boasted about continuing to out-fox the police. The envelopes containing the letters bore the postmark of the coastal town of Sunderland, some 120 kilometres to the north-east of the main locus of the murders. The accent of the speaker in the recorded message was also one associated with the north-east of England (one from a range of varieties popularly referred to as ‘Geordie’). The police misjudged the contents of the communications, taking the view that they contained details of the murders that were not known to the general public. They concluded that the sender was the murderer, and therefore that the murderer came from Sunderland. The two linguists most closely associated with the police investigation, Stanley Ellis and Jack Windsor Lewis, then working at the University of Leeds, saw differently. They strongly believed the letters and recording to be a hoax. They felt compelled to put their view to the officer in charge of the enquiry team. They were ignored. The investigation thus became centred on Sunderland, allowing Sutcliffe, born, bred and still living in West Yorkshire, to continue to murder.
Putative Role of Hyaluronan and Its Related Genes,HAS2andRHAMM, in Human Early Preimplantation Embryogenesis and Embryonic Stem Cell Characterization
Authors: Choudhary Meenakshi , Zhang Xin , Stojković Petra , Hyslop Louise , Anyfantis George , Herbert Mary , Murdoch Alison P. , Stojković Miodrag , Lako Majlinda
Published: September 2007

Human embryonic stem cells (hESC) promise tremendous potential as a developmental and cell therapeutic tool. The combined effort of stimulatory and inhibitory signals regulating gene expression, which drives the tissue differentiation and morphogenetic processes during early embryogenesis, is still very poorly understood. With the scarcity of availability of human embryos for research, hESC can be used as an alternative source to study the early human embryogenesis. Hyaluronan (HA), a simple hydrating sugar, is present abundantly in the female reproductive tract during fertilization, embryo growth, and implantation and plays an important role in early development of the mammalian embryo. HA and its binding protein RHAMM regulate various cellular and hydrodynamic processes from cell migration, proliferation, and signaling to regulation of gene expression, cell differentiation, morphogenesis, and metastasis via both extracellular and intracellular pathways. In this study, we show for the first time that HA synthase gene HAS2 and its binding receptor RHAMM are differentially expressed during all stages of preimplantation human embryos and hESC. RHAMM expression is significantly downregulated during differentiation of hESC, in contrast to HAS2, which is significantly upregulated. Most importantly, RHAMM knockdown results in downregulation of several pluripotency markers in hESC, induction of early extraembryonic lineages, loss of cell viability, and changes in hESC cycle. These data therefore highlight an important role for RHAMM in maintenance of hESC pluripotency, viability, and cell cycle control. Interestingly, HAS2 knockdown results in suppression of hESC differentiation without affecting hESC pluripotency. This suggests an intrinsic role for HAS2 in hESC differentiation process. In accordance with this, addition of exogenous HA to the differentiation medium enhances hESC differentiation to mesodermal and cardiac lineages.

Disclosure of potential conflicts of interest is found at the end of this article.
Functional Sarcoplasmic Reticulum for Calcium Handling of Human Embryonic Stem Cell-Derived Cardiomyocytes: Insights for Driven Maturation
Authors: Liu Jing , Fu Ji Dong , Siu Chung Wah , Li Ronald A.
Published: September 2007

Cardiomyocytes (CMs) are nonregenerative. Self-renewable pluripotent human embryonic stem cells (hESCs) can differentiate into CMs for cell-based therapies. In adult CMs, Ca2+-induced Ca2+ release from the sarcoplasmic reticulum (SR) via the ryanodine receptor (RyR) is key in excitation-contraction coupling. Therefore, proper Ca2+ handling properties of hESC-derived CMs are required for their successful functional integration with the recipient heart. Here, we performed a comprehensive analysis of CMs differentiated from the H1 (H1-CMs) and HES2 (HES2-CMs) hESC lines and human fetal (F) and adult (A) left ventricular (LV) CMs. Upon electrical stimulation, all of H1-, HES2-, and FLV-CMs generated similar Ca2+ transients. Caffeine induced Ca2+ release in 65% of FLV-CMs and ∼38% of H1- and HES2-CMs. Ryanodine significantly reduced the electrically evoked Ca2+ transient amplitudes of caffeine-responsive but not -insensitive HES2- and H1-CMs and slowed their upstroke; thapsigargin, which inhibits the sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) pump, reduced the amplitude of only caffeine-responsive HES2- and H1-CMs and slowed the decay. SERCA2a expression was highest in ALV-CMs but comparable among H1-, HES2-, and FLV-CMs. The Na+-Ca2+ exchanger was substantially expressed in both HES2- and H1-CMs relative to FLV- and ALV-CMs. RyR was expressed in HES2-, H1-, and FLV-CMs, but the organized pattern for ALV-CMs was not observed. The regulatory proteins junctin, triadin, and calsequestrin were expressed in ALV-CMs but not HES2- and H1-CMs. We conclude that functional SRs are indeed expressed in hESC-CMs, albeit immaturely. Our results may lead to driven maturation of Ca2+ handling properties of hESC-CMs for enhanced contractile functions.

Disclosure of potential conflicts of interest is found at the end of this article.
Ground improvement techniques beneath existing rail tracks
Authors: Adam D. , Vogel A. , Zimmermann A.
Published: September 2007

Increased demand on rail tracks owing to decreased intervals, heavier and faster trains and the wearing of old railway lines often requires improvement of the ground and sub-ballast beneath conventional ballasted rail tracks. The rail traffic should not be restrained; thus methods are welcome, which allow a soil compaction or replacement of the soil while tracks and sleepers remain in place. In the current paper methods are presented, which allow a deep improvement of poor and soft soil beneath the rail track and a complete exchange of the near-surface rail track structure including the base layers, ballast, sleepers and tracks.

L'augmentation de la demande en rails, due à la réduction des intervalles, à la circulation de trains plus lourds et plus rapides, et à l'état de voies ferrées usées nécessite souvent le renforcement du terrain et du sub-ballast des voies sur ballast traditionnelles. Étant donné qu'il est nécessaire de ne pas entraver la circulation ferroviaire, on recherche des méthodes permettant le tassement du terrain ou le remplacement du sol tout en laissant les rails et les traverses en place. Cette communication présente des méthodes permettant de renforcer des sols de mauvaise qualité et boulants sous la voie ferrée, ainsi que le remplacement intégral de la voie à proximité de la surface, y compris la base, le ballast, les traverses et les rails.
Heavy tamping integrated dynamic compaction control
Authors: Adam D. , Brandl H. , Kopf F. , Paulmichl I.
Published: September 2007

Heavy tamping is a deep dynamic compaction technique and has been increasingly used since the beginning of the 1970s. The present paper reports on in situ measurements and theoretical investigations referring to the decay of free soil vibrations caused by the falling weight after each impact. This behaviour is significant for the respective soil—falling mass interaction and enables a site-specific optimisation of the heavy tamping technique. The field tests comprised acceleration measurements of the falling mass and the soil whereby the falling height was changed repeatedly. The decay of the amplitudes of free vibrations provided a damping coefficient and a damped natural frequency, which are used to determine the Poisson's ratio and the E-modulus of the ground after each impact from numerical calculations. The scope of the research project was to gain a reliable indicator for the degree of compaction of the soil immediately after each impact, and hence obtain a method for compaction control and documentation.

Le pilonnage lourd est une technique de compactage dynamique en profondeur, utilisée de plus en plus depuis le début des années 1970. La présente communication rend compte de mesures in situ et de recherches théoriques portant sur la dégradation des vibrations propres dans le sol, causées par la retombée du poids après chaque impact. Ce comportement est significatif pour l'interaction entre le sol et la masse tombante, et permet d'optimiser la technique du pilonnage lourd spécifiquement pour chaque lieu d'utilisation. Les essais sur place comprenaient des mesures de l'accélération de la masse tombante et du sol, et comportait le changement répété de la hauteur de chute. Le décroissement de l'amplitude des vibrations libres permettait d'obtenir un coefficient d'amortissement et une fréquence amortie naturelle, qui sont utilisés pour déterminer le coefficient de Poisson et le module E du sol après chaque impact, au moyen de calculs numériques. L'objet de ce projet de recherche était d'obtenir une méthode pour le contrô le et la documentation du compactage.
Lethal and sublethal effects of ammonia to juvenileLampsilismussels (unionidae) in sediment and water-only exposures
Authors: Newton Teresa J. , Bartsch Michelle R.
Published: September 2007

We compared the sensitivity of two juvenile unionid mussels (Lampsilis cardium and Lampsilis higginsii) to ammonia in 96-h water-only and sediment tests by use of mortality and growth measurements. Twenty mussels were placed in chambers buried 2.5 cm into reference sediments to approximate pore-water exposure (sediment tests) or elevated above the bottom of the experimental units (water-only tests). In the sediment tests, a pH gradient existed between the overlying water (mean 8.0), sediment–water interface (mean 7.7), and 2.5 cm depth (mean 7.4). We assumed that mussels were exposed to ammonia in pore water and report effect concentrations in pore water, but if they were exposed to the higher pH water, more of the ammonia would be in the toxic un-ionized (NH3) form. The only differences in toxicity and growth between mussel species occurred in some of the water-only tests. In sediment tests, median lethal concentrations (LC50s) ranged from 124 to 125 μg NH3-N/L. In water-only tests, LC50s ranged from 157 to 372 μg NH3-N/L. In sediment tests, median effective concentrations (EC50s based on growth) ranged from 30 to 32 μg NH3-N/L. Juvenile mussels in the water-only tests grew poorly and did not exhibit a dose–response relation. These data demonstrate that growth is a sensitive and valuable endpoint for studies on ammonia toxicity with juvenile freshwater mussels and that growth should be measured via sediment tests.
Intra- and interlaboratory variability in acute toxicity tests with glochidia and juveniles of freshwater mussels (unionidae)
Authors: Wang Ning , Augspurger Tom , Barnhart M. Chris , Bidwell Joseph R. , Cope W. Gregory , Dwyer F. James , Geis Steve , Greer I. Eugene , Ingersoll Chris G. , Kane Cynthia M. , May Thomas W. , Neves Richard J. , Newton Teresa J. , Roberts Andy D. , Whites David W.
Published: September 2007

The present study evaluated the performance and variability in acute toxicity tests with glochidia and newly transformed juvenile mussels using the standard methods outlined in American Society for Testing and Materials (ASTM). Multiple 48-h toxicity tests with glochidia and 96-h tests with juvenile mussels were conducted within a single laboratory and among five laboratories. All tests met the test acceptability requirements (e.g., ≥90% control survival). Intralaboratory tests were conducted over two consecutive mussel-spawning seasons with mucket (Actinonaias ligamentina) or fatmucket (Lampsilis siliquoidea) using copper, ammonia, or chlorine as a toxicant. For the glochidia of both species, the variability of intralaboratory median effective concentrations (EC50s) for the three toxicants, expressed as the coefficient of variation (CV), ranged from 14 to 27% in 24-h exposures and from 13 to 36% in 48-h exposures. The intralaboratory CV of copper EC50s for juvenile fatmucket was 24% in 48-h exposures and 13% in 96-h exposures. Interlaboratory tests were conducted with fatmucket glochidia and juveniles by five laboratories using copper as a toxicant. The interlaboratory CV of copper EC50s for glochidia was 13% in 24-h exposures and 24% in 48-h exposures, and the interlaboratory CV for juveniles was 22% in 48-h exposures and 42% in 96-h exposures. The high completion success and the overall low variability in test results indicate that the test methods have acceptable precision and can be performed routinely.
Chronic toxicity of copper and ammonia to juvenile freshwater mussels (unionidae)
Authors: Wang Ning , Ingersoll Christopher G. , Greer I. Eugene , Hardesty Douglas K. , Ivey Christopher D. , Kunz James L. , Brumbaugh William G. , Dwyer F. James , Roberts Andy D. , Augspurger Tom , Kane Cynthia M. , Neves Richard J. , Barnhart M. Chris
Published: September 2007

The objectives of the present study were to develop methods for conducting chronic toxicity tests with juvenile mussels under flow-through conditions and to determine the chronic toxicity of copper and ammonia to juvenile mussels using these methods. In two feeding tests, two-month-old fatmucket (Lampsilis siliquoidea) and rainbow mussel (Villosa iris) were fed various live algae or nonviable algal mixture for 28 d. The algal mixture was the best food resulting in high survival (≥90%) and growth. Multiple copper and ammonia toxicity tests were conducted for 28 d starting with two-month-old mussels. Six toxicity tests using the algal mixture were successfully completed with a control survival of 88 to 100%. Among copper tests with rainbow mussel, fatmucket, and oyster mussel (Epioblasma capsaeformis), chronic value ([ChV], geometric mean of the no-observed-effect concentration and the lowest-observed-effect concentration) ranged from 8.5 to 9.8 μg Cu/L for survival and from 4.6 to 8.5 μg Cu/L for growth. Among ammonia tests with rainbow mussel, fatmucket, and wavy-rayed lampmussel (L. fasciola), the ChV ranged from 0.37 to 1.2 mg total ammonia N/L for survival and from 0.37 to 0.67 mg N/L for growth. These ChVs were below the U.S. Environmental Protection Agency 1996 chronic water quality criterion (WQC) for copper (15 μg/L; hardness 170 mg/L) and 1999 WQC for total ammonia (1.26 mg N/L; pH 8.2 and 20°C). Results indicate that toxicity tests with two-month-old mussels can be conducted for 28 d with >80% control survival; growth was frequently a more sensitive endpoint compared to survival; and the 1996 chronic WQC for copper and the 1999 chronic WQC for total ammonia might not be adequately protective of the mussel species tested. However, a recently revised 2007 chronic WQC for copper based on the biotic ligand model may be more protective in the water tested.
Acute and chronic toxicity of pesticide formulations (atrazine, chlorpyrifos, and permethrin) to glochidia and juveniles ofLampsilis siliquoidea
Authors: Bringolf Robert B. , Cope W. Gregory , Barnhart M. Chris , Mosher Shad , Lazaro Peter R. , Shea Damian
Published: September 2007

Freshwater mussels are among the most imperiled faunal groups in North America; approximately 67% of the nearly 300 native freshwater mussel species (family Unionidae) are listed as endangered, threatened, or of special concern. Despite evidence that glochidia and juvenile life stages are highly sensitive to some chemical contaminants, the effects of pesticides on early life stages of unionid mussels are largely unknown. In the United States, pesticide registration is based on toxicity data of the active ingredient, not formulations as they are sold and applied. Some pesticide formulations, however, are more toxic than their active ingredient (technical-grade pesticide) alone because of the presence of surfactants, adjuvants, or other ingredients in the formulation. The objective of the present study was to compare the toxicity of active ingredients of several current-use pesticides (atrazine, chlorpyrifos, and permethrin) to the toxicity of pesticide formulations to glochidia and juvenile life stages of a freshwater mussel (Lampsilis siliquoidea). The atrazine formulation (Aatrex) was more toxic than technical-grade atrazine in chronic tests with juvenile L. siliquoidea. For other pesticides, acute and chronic toxicity of technical-grade pesticides were similar to the toxicity of pesticide formulations. Median effective concentrations for chlorpyrifos were 0.43 mg/L for glochidia at 48 h, 0.25 mg/L for juveniles at 96 h, and 0.06 mg/L for juveniles at 21 d. Atrazine and permethrin as well as their formulations did not cause significant acute toxicity in glochidia or juveniles at exposure concentrations approaching water-solubility limits. Additional research is needed on other pesticides with different modes of action, on the role of different routes of exposure, and with other species of unionid mussels to evaluate similarities of toxic response.
An evaluation of freshwater mussel toxicity data in the derivation of water quality guidance and standards for copper
Authors: March Ferrella A. , Dwyer F. James , Augspurger Tom , Ingersoll Christopher G. , Wang Ning , Mebane Christopher A.
Published: September 2007

The state of Oklahoma has designated several areas as freshwater mussel sanctuaries in an attempt to provide freshwater mussel species a degree of protection and to facilitate their reproduction. We evaluated the protection afforded freshwater mussels by the U.S. Environmental Protection Agency (U.S. EPA) hardness-based 1996 ambient copper water quality criteria, the 2007 U.S. EPA water quality criteria based on the biotic ligand model and the 2005 state of Oklahoma copper water quality standards. Both the criterion maximum concentration and criterion continuous concentration were evaluated. Published acute and chronic copper toxicity data that met American Society for Testing and Materials guidance for test acceptability were obtained for exposures conducted with glochidia or juvenile freshwater mussels. We tabulated toxicity data for glochidia and juveniles to calculate 20 species mean acute values for freshwater mussels. Generally, freshwater mussel species mean acute values were similar to those of the more sensitive species included in the U.S. EPA water quality derivation database. When added to the database of genus mean acute values used in deriving 1996 copper water quality criteria, 14 freshwater mussel genus mean acute values included 10 of the lowest 15 genus mean acute values, with three mussel species having the lowest values. Chronic exposure and sublethal effects freshwater mussel data available for four species and acute to chronic ratios were used to evaluate the criterion continuous concentration. On the basis of the freshwater mussel toxicity data used in this assessment, the hardness-based 1996 U.S. EPA water quality criteria, the 2005 Oklahoma water quality standards, and the 2007 U.S. EPA water quality criteria based on the biotic ligand model might need to be revised to afford protection to freshwater mussels.
Risk assessment of water quality in three North Carolina, USA, streams supporting federally endangered freshwater mussels (unionidae)
Authors: Ward Sara , Augspurger Tom , Dwyer F. James , Kane Cindy , Ingersoll Christopher G.
Published: September 2007

Water quality data were collected from three drainages supporting the endangered Carolina heelsplitter (Lasmigona decorata) and dwarf wedgemussel (Alasmidonta heterodon) to determine the potential for impaired water quality to limit the recovery of these freshwater mussels in North Carolina, USA. Total recoverable copper, total residual chlorine, and total ammonia nitrogen were measured every two months for approximately a year at sites bracketing wastewater sources and mussel habitat. These data and state monitoring datasets were compared with ecological screening values, including estimates of chemical concentrations likely to be protective of mussels, and federal ambient water quality criteria to assess site risks following a hazard quotient approach. In one drainage, the site-specific ammonia ecological screening value for acute exposures was exceeded in 6% of the samples, and 15% of samples exceeded the chronic ecological screening value; however, ammonia concentrations were generally below levels of concern in other drainages. In all drainages, copper concentrations were higher than ecological screening values most frequently (exceeding the ecological screening values for acute exposures in 65–94% of the samples). Chlorine concentrations exceeding the acute water quality criterion were observed in 14 and 35% of samples in two of three drainages. The ecological screening values were exceeded most frequently in Goose Creek and the Upper Tar River drainages; concentrations rarely exceeded ecological screening values in the Swift Creek drainage except for copper. The site-specific risk assessment approach provides valuable information (including site-specific risk estimates and ecological screening values for protection) that can be applied through regulatory and nonregulatory means to improve water quality for mussels where risks are indicated and pollutant threats persist.
Extraction and bioanalysis of the ecotoxicologically relevant fraction of contaminants in sediments
Authors: Puglisi Edoardo , Murk Albertinka J. , van den Berg Hans J. , Grotenhuis Tim
Published: September 2007

Assessments of the risk connected to the contamination of soils and sediments should rely on a multidisciplinary approach based on both chemical and biological techniques (i.e., the sum of exposure and effects assessment). The dioxin-responsive, chemical-activated luciferase expression (DR-CALUX) bioassay is widely applied for evaluation of the toxicity of sediments after an exhaustive extraction of the contaminants, and results are used for risk assessment purposes. Approaches based on total extraction of contaminants do not take into account the importance of bioavailability and aging processes, thus leading to possible overestimations of risk. In the present work, an approach based on nonexhaustive extraction techniques in combination with an in vitro reporter gene assay was tested on sediment samples contaminated with dioxins, polycyclic aromatic hydrocarbons, polychlorinated biphenyls (PCBs), and other xenobiotics. Tenax and hydroxypropyl-β-cyclodextrin (HPCD) extractions over time were carried out to determine the bioavailable fractions, whereas the residual fractions were determined by means of a microwave-assisted exhaustive extraction. For both fractions, contaminant concentrations were quantified by gas chromatography-mass spectrophotometry, and the toxic potency was determined by the DR-CALUX assay. Assessments of bioavailable fractions of PCBs by Tenax and HPCD gave comparable results and showed that after several years of aging, a considerable fraction (38–70% of the total content for different PCBs) is still available and ecotoxicologically relevant. Coupling of nonexhaustive extraction and bioanalyses leads to a more realistic and, generally, much lower estimated risk for the toxicity of the extracts as compared to commonly adopted exhaustive techniques.
Spatial and temporal evaluation of metal concentrations in soils and sediments from new orleans, louisiana, USA, following hurricanes Katrina and Rita
Authors: Abel Michael T. , Presley Steven M. , Rainwater Thomas R. , Austin Galen P. , Cox Stephen B. , McDaniel Les N. , Marsland Eric J. , Leftwich Blair D. , Anderson Todd A. , Kendall Ronald J. , Cobb George P.
Published: September 2007

During January 2006, soil and sediment samples from 75 sites in the New Orleans (LA, USA) area were collected and tested for 26 inorganic elements. The study design was intended to provide a spatial pattern of metal concentrations within the city following hurricanes Katrina and Rita. The sampling design included four transects that traversed the city in a north–south direction and three transects that traversed the city in an east–west direction. Contaminant concentrations were determined at multiple sites within each transect and compared to U.S. Environmental Protection Agency soil screening criteria pertaining to human health. Concentrations of Pb and As exceeded the criteria indiscriminately throughout the city. Of the 75 sites, 14 (19%) exceeded the soil screening criteria for Pb, and 73 (97%) exceeded the criteria for As. Forty-three of the 75 sites coincided with a previous sampling event in October 2005. Metal concentrations were evaluated for temporal comparisons using a pair sampled t test. Arsenic concentrations differed significantly over time, but Pb concentrations did not.
Use of the australian crimson-spotted rainbowfish (Melanotaenia fluviatilis) as a model test species for investigating the effects of endocrine disruptors
Authors: Pollino Carmel A. , Georgiades Eugene , Holdway Douglas A.
Published: September 2007

Few studies have investigated the potential reproductive effects of toxicants on Australian freshwater fish species. The present study uses the Australian rainbowfish (Melanotaenia fluviatilis) as a model for testing the potential effects of 17β-estradiol. Groups of reproductively active rainbowfish were exposed to waterborne 17β-estradiol (control, carrier control, and 30, 100, 300, and 1,000 ng/L) for 3- and 14-d periods. Biomarkers of both low ecological relevance (plasma estradiol and testosterone, phosphoprotein, γ-glutamyltranspeptidase [GTP]) and high ecological relevance (egg counts, hatchability, larval lengths, histopathology) were measured and the relationships between these examined. Relative to the controls, exposed female rainbowfish had a decline in plasma estradiol. An increase in phosphoprotein (vitellogenin) also was observed after exposure to 1,000 ng/L after 3 d, and histological examination of the gonads showed an increase in oocyte atresia at 1,000 ng/L on days 3 and 14. Changes in egg production were observed at 300 and 1,000 ng/L. No changes were detected to egg hatchability and larval lengths of offspring. Although there were no changes in male rainbowfish plasma testosterone or the histological organization of testes, levels of phosphoprotein increased and GTP activities were increased after 3 d of exposure at all test concentrations, but these declined at day 14. The present study demonstrated that, though measurements at the biochemical level were responsive to 17β-estradiol exposure, fewer changes were observed in markers of higher ecological relevance at the exposures concentrations and durations tested.
Can the unit world model concept be applied to hazard assessment of both organic chemicals and metal ions?
Authors: Harvey Colin , Mackay Don , Webster Eva
Published: September 2007

A unit world model that has the potential to be used for the hazard assessment of both metal ions and organic chemicals is described and discussed, with an emphasis on the problems that arise when treating metal ions. It is based on the steady-state equilibrium criterion model that is designed to simulate the fate of organic chemicals in a 100,000-km2 region and comprises four well-mixed compartments: Air, water, soil, and sediment. To be applicable to metal ions, modifications are required. The single soil and sediment layers should be replaced by two layers to accommodate aerobic and anaerobic conditions. The more complex and variable partitioning of metals resulting from dependence on pH, redox conditions, ionic oxidation state, and presence of sulfide also must be addressed, but preferably in a separate geochemical model, because these factors can result in nonlinearity. For metals, a dynamic as well as a steady-state model is desirable. It is shown that the resulting model can be applied to both organics and metals. Rather than seeking to apply the hazard criterion of persistence to metal ions, the model can be used to deduce a critical loading that results in a defined toxic end point, thus integrating the hazard criteria of persistence, toxicity, and possibly, bioaccumulation. This approach is applied illustratively to naphthalene as a typical organic substance and to four environmentally relevant metal ions. Results are discussed and recommendations made for further development. Specifically, the absence of metal degradation can result in large, steady-state quantities in soils and sediments corresponding to residence times of many centuries. Consequently, the dynamic calculations are more relevant for fate assessments of metals over a period of years, and more focus on the aquatic environment is justified.
Validation study of the acute biotic ligand model for silver
Authors: Bielmyer Gretchen K. , Grosell Martin , Paquin Paul R. , Mathews Rooni , Wu Kuen B. , Santore Robert C. , Brix Kevin V.
Published: September 2007

An important final step in development of an acute biotic ligand model for silver is to validate predictive capabilities of the biotic ligand model developed for fish and invertebrates. To accomplish this, eight natural waters, collected from across North America, were characterized with respect to ionic composition, pH, dissolved organic carbon, and sulfide. Tests were conducted with the cladoceran Ceriodaphnia dubia (48-h static) and the fish Pimephales promelas (96-h static renewal) to determine the concentrations causing lethality to 50% of the organisms (LC50s) for silver in each of these waters. Overall, the biotic ligand model adequately predicted silver toxicity to C. dubia; however, in some cases, predicted LC50 values exceeded measured values. The accuracy of the biotic ligand model predictions was less convincing for silver toxicity to P. promelas with pronounced problems in low–ionic strength waters. Another issue was the use of acclimated organisms in toxicity studies because the biotic ligand model has been developed with the use of a mix of studies with acclimated and nonacclimated test organisms of varying ages and sizes. To evaluate whether effects of acclimation to test waters influence biotic ligand model predictions, a subset of the natural waters were also tested with P. promelas that had been acclimated to the natural water for 7 d before testing. These experiments revealed no differences in toxicity between acclimated and nonacclimated P. promelas. To determine the influence of organism size, which has been previously correlated to Na+ turnover and acute silver toxicity across multiple species, Na+ and Cl− influx rates were measured in P. promelas of different sizes. Our results show that Na+ and Cl− influx rates were inversely related to fish mass and positively correlated with silver sensitivity.
Dynamics of benazolin under the influence of degrading maize straw in undisturbed soil columns
Authors: Berns Anne E. , Schnitzler Frauke , Drewes Norbert , Vereecken Harry , Burauel Peter
Published: September 2007

The effect of organic carbon amendment on the fate of benazolin was investigated in undisturbed soil columns. The soil columns were obtained from three different soil types located in three different regions with different crop production regimes. All soils were operated in a normal crop production regime, and one of the soils was additionally operated in low and high crop production regimes. Two experimental setups were conducted, one using [14C]maize straw and nonlabeled benazolin and one using nonlabeled maize straw and [14C]benazolin. The column experiments with [14C]maize straw showed that the residual crop residues remained mainly in the top layer. Benazolin and its metabolites showed a higher retention in columns that were amended with maize straw compared to column without amendment. The production regimes of the soils did not influence the behavior of benazolin. The effect of maize straw incorporation on the translocation and degradation of benazolin could well be caused by a change in the soil microbial activity, leading to an enhanced degradation of benazolin and producing metabolites exhibiting a sorption behavior different from the parent.
An individual-based approach to model spatial population dynamics of invertebrates in aquatic ecosystems after pesticide contamination
Authors: Van den Brink Paul J. , (Hans) Baveco J. M. , Verboom Jana , Heimbach Fred
Published: September 2007

In the present study we present a population model (Metapopulation model for Assessing Spatial and Temporal Effects of Pesticides [MASTEP]) describing the effects on and recovery of the waterlouse Asellus aquaticus after exposure to a fast-acting, nonpersistent insecticide as a result of spray drift in pond, ditch, and stream scenarios. The model used the spatial and temporal distribution of the exposure in different treatment conditions as an input parameter. A dose–response relation derived from a hypothetical mesocosm study was used to link the exposure with the effects. The modeled landscape was represented as a lattice of 1- by 1-m cells. The model included processes of mortality of A. aquaticus, life history, random walk between cells, density dependence of population regulation, and, in the case of the stream scenario, medium-distance drift of A. aquaticus due to flow. All parameter estimates were based on expert judgment and the results of a thorough review of published information on the ecology of A. aquaticus. In the treated part of the water body, the ditch scenario proved to be the worst-case situation, due to the absence of drift of A. aquaticus. Effects in the pond scenario were smaller because the pond was exposed from one side, allowing migration from the other, less contaminated side. The results of the stream scenario showed the importance of including drift for the population recovery in the 100-m stretch of the stream that was treated. It should be noted, however, that the inclusion of drift had a negligible impact on numbers in the stream as a whole (600 m).
A noninvasive test of exposition to toxicants: Quantitative analysis of cytochrome P4501A expression in fish scales
Authors: Quirós Laia , Raldúa Demetrio , Navarro Anna , Casado Marta , Barceló Damià , Piña Benjamin
Published: September 2007

Elevated expression of cytochrome P4501A (CYP1A) is an established biomarker for exposition to a wide range of toxicants, particularly for dioxin and structurally similar compounds. Expression of CYP1A usually is analyzed in internal organs, which involves dissection of the specimen. To avoid unnecessary animal killing, we present here an alternative method based on the monitoring of CYP1A expression in fish scales. Using β-naphthoflavone (BNF; 50 mg/kg body wt, intraperitoneal injection) as inducer in goldfish (Carassius auratus), we monitored levels of CYP1A mRNA both in scales and liver of treated and control specimens. Treatment with BNF resulted in a similar induction of CYP1A gene in both tissues, although scales responded faster (at 8 h after treatment) than liver (between 24 and 48 h). The scale-based test has the unique advantage of allowing sequential testing in the same specimen, which facilitates analysis of the time course of CYP1A induction and allows the study of individual variability. The method implies minimal suffering of the animals, because it only requires removal of a moderate (n = 1–3) number of scales for each time point. This nondestructive, fast, and relatively inexpensive test for toxic exposure therefore is suitable for environmental monitoring and food safety control programs in which specimen preservation is required.
A control chart approach to monitoring and communicating trends in tissue selenium concentrations
Authors: Chapman Peter M. , deBruyn Adrian M. H.
Published: September 2007

A primary aim of monitoring programs is to determine changes relative to background conditions, which typically represent a distribution of values, not a single value, and which may be elevated naturally. Graphical inspection of the statistical distribution of background and subsequent data provides the best means to determine changes over time and the relative significance of those changes based on both their magnitude and trajectory. The control chart approach commonly used in laboratory and product testing is a useful tool that allows for such determinations in a manner that is transparent to both scientists and nonscientists. This approach can be used both with true baseline (i.e., pre-development) data and with operational baseline (i.e., post-development) data and is particularly relevant for monitoring selenium (Se) tissue concentrations.
Activated carbon amendment as a treatment for residual ddt in sediment from a superfund site in San Francisco Bay, Richmond, California, USA
Authors: Tomaszewski Jeanne E. , Werner David , Luthy Richard G.
Published: September 2007

Pesticide formulators formerly operating at Lauritzen Channel, a portion of San Francisco Bay near Richmond (CA, USA), caused contamination of sediment with dichlorodiphenyltrichloroethane (DDT). The present study evaluated the distribution of residual DDT in channel sediment six years following extensive remedial dredging. High DDT concentrations (up to 252 mg/kg) were found in Young Bay Mud sampled across the channel. Particle analyses showed most of the contamination is contained in the clay/silt sediment fraction, and desorption tests showed that availability is greater for DDT metabolites than parent DDT. The present study examined the feasibility of using activated carbon amendment to sequester DDT from sediment, including an evaluation of reactivated carbon as a less costly alternative to virgin activated carbons. Treatment success of activated carbon amendment to sediment collected from Lauritzen Channel was measured by reductions in aqueous equilibrium concentrations and uptake in semipermeable membrane devices (SPMDs). Four different activated carbons were tested and, after one month of treatment with 3.2 weight % carbon, DDT aqueous equilibrium concentrations were reduced up to 83% and SPMD uptake was reduced up to 91%. Reactivated carbon was comparable with virgin carbons in all tests. Reduction in SPMD uptake of DDT by treatment with 3.2% reactivated carbon increased to 99% after 26 months of treatment. The effectiveness of activated carbon was dependent on the type, size, dose, and contact time. The results show the potential usefulness of activated carbon amendment as a follow-up remedial technology for management of residuals after dredging contaminated sediment.