bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecular multi‐effect screening of environmental pollutants using the MolDarT
Authors: Liedtke Anja , Muncke Jane , Rüfenacht Karin , Eggen Rik I. L.
Published: January 2008

Molecular effect detection is a useful approach for ecotoxicological screening of chemicals. We show here the application of the molecular DarT (MolDarT), where the expression of selected target genes is detected in short‐term (120 h) exposed developing zebrafish (Danio rerio), thus allowing subacute multi‐effect compound screening. The genes metallothionein 2 (mt2), cytochrome P450 1A1 (cyp1a1), and recombination activation gene 1 (rag1) are used as endpoints that describe detoxification/metal toxicity (mt2), detoxification/PAH toxicity (cyp1a1), and acquired immune system disruption (rag1). Each gene's developmental expression was studied in unexposed zebrafish during 4 to 120 h past fertilization (hpf), and all three genes were found to be expressed at 120 hpf. Furthermore, mt2 transcripts were present at high levels at 4 hpf, indicating a maternal transfer. For positive toxicity controls, freshly fertilized zebrafish eggs were exposed for 120 hpf to ZnSO4, 1,5‐dimethylnaphthalene (DMN) and CdCl2. Exposure to 100 and 200 μM ZnSO4 significantly induced mt2; 10 μM DMN and 20 μM DMN resulted in significantly increased cyp1a1 abundance; and 5 and 10 μM CdCl2 significantly reduced rag1 expression levels. Furthermore, we analysed these target genes for their expression in zebrafish eggs from a previous exposure study. The eggs were exposed for 120 hpf to the environmental pollutants estradiol (E2), ethinylestradiol (EE2), nonylphenol (NP), atrazine, cyproconazol, and bisphenol A (BPA) and found differential expression of the three genes. Exposure to the (xeno‐)estrogenic compound NP (0.75 μM) significantly lowered mt2 expression. This study shows the potential of short‐term in vivo multi‐effect screenings within one single subacute exposure using the MolDarT. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2008.
Biomarkers for exposure to estrogenic compounds: Gene expression analysis in zebrafish (Danio rerio)
Authors: Kausch Ulf , Alberti Martin , Haindl Stefanie , Budczies Jan , Hock Bertold
Published: January 2008

Gene expression analyses in male zebrafish (Danio rerio) were carried out using microarray technique and quantitative polymerase chain reaction. Genes responding to the exposure to 17β‐estradiol, bisphenol A and genistein were identified, among them genes involved in metabolism, reproductional and developmental processes. Threshold levels of 17β‐estradiol (200 ng/L), bisphenol A (2000 μg/L), and genistein (5000 μg/L) for the upregulation of the vtg1 gene in short‐time exposures (11 days) were determined by qPCR. 14k microarrays were used to generate complete lists of genes regulated by these estrogenic compounds. For this purpose, liver samples from 10 exposed zebrafish and 10 controls were processed. In this case the expressions of 211 genes were significantly regulated by 17β‐estradiol, 47 by bisphenol A and 231 by genistein. Furthermore, it is shown that fish exposed to 17β‐estradiol and genistein have similarities in their gene expression patterns, whereas bisphenol A apparently affected gene expression in a different way. Only genes coding for egg‐yolk precursor protein vitellogenin were found to be regulated by all three compounds, which shows that these genes are the only suitable markers for exposure to different estrogenic compounds. The regulated genes were assigned to gene ontology classes. All three estrogenic compounds regulated genes mainly involved in primary and cellular metabolism, but genistein regulated several genes involved in cell cycle‐regulation and bisphenol A several genes involved in protein biosynthesis. Genistein also upregulated the expression of four eggshell proteins, which can be used as biomarkers for exposure to this chemical. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2008.
Evaluating wastewater‐induced plant genotoxicity using randomly amplified polymorphic DNA
Authors: Swaileh K. M. , Hussein R. , Ezzughayyar A.
Published: January 2008

Wastewater often contains genotoxic substances that can resist different stages of the treatment process. In the present study, randomly amplified polymorphic DNA technology was applied to evaluate the genotoxic effects of wastewater (treated and raw) irrigation on oat plants (Avena sativa). RAPD profiles obtained showed that both treated and raw wastewater (RWW) were having genotoxic effects on oat plants. This was apparent by the appearance/disappearance of bands in the treatments compared with the control plants. From the 15 primers used, 186 bands were obtained with an average of 12.4 bands per primer. Irrigating plants with RWW caused 51 new bands to appear and 19 to disappear. Treated wastewater (TWW) caused only 16 new bands and the loss of 17 bands. This makes TWW less genotoxic than RWW. The Euclidean distances shown on the dendrogram, revealed the presence of two clusters according to dissimilarity values. One cluster contained the control plants and those irrigated with TWW, whereas the second contained the plants irrigated with RWW. Similarity indices calculated between the treatments and the control plants showed that the control and the plants irrigated with TWW had a similarity index of 0.87, the control and plants irrigated with RWW 0.73 and between the treatments 0.75. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2008.
Effects of a saxitoxin‐producer strain of Cylindrospermopsis raciborskii (cyanobacteria) on the swimming movements of cladocerans
Authors: Filho Aloysio da S. Ferrão , da Costa Simone M. , Ribeiro Manuel Gustavo Leitão , Azevedo Sandra M. F. O.
Published: January 2008

This study evaluated the effects of a saxitoxin‐producer strain (T3) of the cyanobacteria species Cylindrospermopsis raciborskii on the swimming movements of three cladoceran species (Daphnia gessneri, D. pulex, and Moina micrura). Acute toxicity bioassays were designed to access the effects of T3 strain, of a nonsaxitoxin producer strain (NPLP‐1) of the same species and of a raw water sample from Funil reservoir (Rio de Janeiro, Brazil), that contained this and other cyanobacteria. In the acute bioassays, animals were exposed to C. raciborskii filaments or Funil water for 24–48 h and then transferred to food suspensions without cyanobacterial filaments for a further 48 h. During the exposure time to T3 strain filaments there was a decrease in the number of swimming individuals, with animals showing progressive immobilization. The same effect was observed with Funil water sample. Animals stayed alive on the bottom of the test tube and recovered swimming movements when transferred to food suspensions without toxic cells. This effect was not observed with the strain NPLP‐1. The cladoceran D. pulex showed to be extremely sensitive to T3 strain and to Funil water containing C. raciborskii filaments, showing complete paralysis after 24‐h exposure to T3 cell densities of 103 and 104 cells mL−1, and after 24‐h exposure to only 10% of raw water. However, D. gessneri was not sensitive to both T3 and to Funil water, whereas M. micrura was intermediate in sensitivity. This is the first report on the effects of cyanobacterial saxitoxins on movements of freshwater cladocerans, showing also difference in sensitivity among closely related Daphnia species. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2008.
Algicidal activity of phthalocyanines—Screening of 31 compounds
Authors: Jančula Daniel , Drábková Michaela , Černý Jiří , Karásková Marie , Kořínková Radka , Rakušan Jan , Maršálek Blahoslav
Published: January 2008

Phthalocyanines and their analogues show great potential as photodynamic agents producing reactive oxygen species (ROS), especially in medicine. However, their biocidal effects may also be employed to inhibit various undesirable organisms. This study explores their potential algicidal effects. The laboratory tests concern the effects of various phthalocyanine derivatives on the green alga Pseudokirchneriella subcapitata and cyanobacterium Synechococcus nidulans. Their effects on one example of the sensitive nontarget aquatic organism—crustacean Daphnia magna were also screened. Among 31 tested compounds, the cationic phthalocyanines substituted with heterocycle exhibited the strongest effects on phytoplankton species, some of them even below the level of 1 mg/L, while effects on crustaceans ranged from 3.6 to more than 50 mg/L. These results show that some phthalocyanine derivatives can act as potent algicides. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2008.
Toxicity of the antimicrobial compound triclosan and formation of the metabolite methyl‐triclosan in estuarine systems
Authors: DeLorenzo M. E. , Keller J. M. , Arthur C. D. , Finnegan M. C. , Harper H. E. , Winder V. L. , Zdankiewicz D. L.
Published: January 2008

Triclosan, a commonly used antimicrobial compound, has been measured in aquatic systems worldwide. This study exposed marine species to triclosan to examine effects primarily on survival and to investigate the formation of the degradation product, methyl‐triclosan, in the estuarine environment. Acute toxicity was assessed using the bacterium Vibrio fischeri, the phytoplankton species Dunaliella tertiolecta, and three life stages of the grass shrimp Palaemonetes pugio. P. pugio larvae were more sensitive to triclosan than adult shrimp or embryos. Acute aqueous toxicity values (96 h LC50) were 305 μg/L for adult shrimp, 154 μg/L for larvae, and 651 μg/L for embryos. The presence of sediment decreased triclosan toxicity in adult shrimp (24 h LC50s were 620 μg/L with sediment, and 482 μg/L without sediment). The bacterium was more sensitive to triclosan than the grass shrimp, with a 15 min aqueous IC50 value of 53 μg/L and a 15 min spiked sediment IC50 value of 616 μg/kg. The phytoplankton species was the most sensitive species tested, with a 96 h EC50 value of 3.55 μg/L. Adult grass shrimp were found to accumulate methyl‐triclosan after a 14‐day exposure to 100 μg/L triclosan, indicating formation of this metabolite in a seawater environment and its potential to bioaccumulate in higher organisms. Triclosan was detected in limited surface water sampling of Charleston Harbor, SC at a maximum concentration of 0.001 μg/L, substantially lower than the determined toxicity values. These findings suggest triclosan poses low acute toxicity risk to estuarine organisms; however, the potential for chronic, sublethal, and metabolite effects should be investigated. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2008.
Relative biological effectiveness of fast neutrons in a multiorgan assay for apoptosis in mouse
Authors: Lee Hae‐June , Kim Joong‐Sun , Moon Changjong , Kim Jong‐Choon , Jo Sung‐Kee , Kim Sung‐Ho
Published: January 2008

This study compared the effects of high linear energy transfer (LET) fast neutrons on the induction of apoptosis in several tissue types (hair follicle, intestine crypt, testis) of ICR mouse exposed to low LET 60Co γ‐rays. The changes that occurred from 0 to 24 h after exposing the mice to either 2 Gy of γ‐rays (2 Gy/min) or 0.8 Gy of neutrons (94 mGy/min, 35 MeV) were examined. The maximum frequency of apoptosis was observed at 8 or 12 h after irradiation. The mice that had received 0–8 Gy of γ‐rays or 0–1.6 Gy of neutrons were examined 8 h after irradiation. The best‐fitting dose–response curves were linear‐quadratic, and there was a significant relationship between the number of apoptotic cells and the dose. The stained products in the TUNEL‐positive cells or bodies correlated with the typical morphologic characteristics of apoptosis observed by optical microscopy. In the follicles showing an apoptosis frequency between 2 and 14 per hair follicle, the relative biological effectiveness (RBE) of the neutrons in the small and large follicles was 2.09 ± 0.31 and 2.15 ± 0.18, respectively. In the intestine crypts showing an apoptosis frequency between 1 and 3 per crypt, the RBE of the neutrons was 4.03 ± 0.06 and 3.87 ± 0.04 in the base and total crypts, respectively. The RBE of the neutrons in the seminiferous tubule showing an apoptosis frequency between 0.5 and 2 per tubule was 5.18 ± 0.06. The results determined the time–response relations and the RBE for fast neutron‐induced apoptosis in several organs at the same time. The differences in RBE observed between the high and low LET radiation and it is believed that the difference in the DSB repair capacity in hair follicle, intestine crypt, and seminiferous tubule cells plays a role in determining the RBE of the high‐LET radiation for the induced apoptotic cell formation. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2008.
Inorganic arsenic induces necrosis of human CD34‐positive haematopoietic stem cells
Authors: Vernhet Laurent , Morzadec Claudie , van Grevenynghe Julien , Bareau Benoît , Corolleur Michel , Fest Thierry , Fardel Olivier
Published: January 2008

Inorganic arsenic is a major environmental contaminant known to exert immunosuppressive effects. In this study, we report toxicity of As2O3, a trivalent inorganic form, toward isolated human hematopoietic CD34+ progenitor cells. Our results demonstrate that low concentrations of As2O3 (0.1–5 μM) inhibit in vitro proliferation of CD34+ cells and their differentiation into various hematological cell lineages. These effects were associated with the induction of a necrotic process independent of caspases and likely related to mitochondrial damage. We conclude that As2O3 can impair in vitro human hematopoiesis by decreasing survival of CD34+ progenitor cells. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2008.
Tissue‐specific cadmium and metallothionein levels in freshwater crab Sinopotamon henanense during acute exposure to waterborne cadmium
Authors: Ma Wenli , Wang Lan , He Yongji , Yan Yao
Published: January 2008

The freshwater crabs Sinopotamon henanense were exposed to different concentrations of waterborne cadmium (Cd). The relationship between tissue‐specific Cd accumulation and metallothionein (MT) induction was investigated using the Cd saturation assay and atomic absorption spectrophotometry method. The results showed that Cd accumulation rose significantly in all tissues studied after Cd exposure, and the Cd accumulation level in various tissues followed the following order: gill > hepatopancreas > muscle > ovary. MT levels were clearly tissue‐specific after Cd exposure. Hepatopancreas was found to have the highest MT level, followed by the gill, muscle, and ovary. In conclusion, the results indicated although Cd exposure clearly resulted in MT induction, its synthesis does not correlate with Cd accumulation in the later stage of Cd exposure. The calculated ratios of actual Cd to theoretical maximum Cd‐MT in the hepatopancreas were <1.0 under acute waterborne Cd at all sampling points, indicating that the hepatopancreas had much greater Cd‐binding potential of MT than the gill, muscle, or ovary. It is clear from our results that a positive correlation was shown between MT induction and Cd accumulation both in hepatopancreas and gill. Therefore, MT induction can be considered as a biomarker for acute waterborne Cd pollution. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2008.
Response of antioxidant enzymes in coontail (Ceratophyllum demersum L.) plants under cadmium stress
Authors: Mishra Seema , Srivastava Sudhakar , Tripathi R. D. , Dwivedi Sanjay , Shukla M. K.
Published: January 2008

Cadmium (Cd) contamination of aquatic systems is of major concern since it is a nonessential element and hampers plant growth upon accumulation. The aim of this study was to investigate the Cd accumulation behavior of coontail plant, Ceratophyllum demersum L., toxicity induced and response of the antioxidant system. Plants were exposed to various concentrations of Cd (0–10 μM) for a period of 1–7 days. Accumulation of Cd was found to be a concentration duration dependent phenomenon. The maximum accumulation of Cd, 1293 μg g−1 dw, was observed after 7 days at 10 μM. Plants showed significant stimulation of the activities of various antioxidant enzymes viz., superoxide dismutase (EC 1.15.1.1), ascorbate peroxidase (EC 1.11.1.11), guaiacol peroxidase (EC 1.11.1.7), catalase (EC 1.11.1.6), and glutathione reductase (EC 1.6.4.2) and tolerated toxicity of Cd up to moderate concentration of 5 μM. At 10 μM exposure, enzyme activities declined and plants experienced toxicity, which was evident by the significant decrease in the photosynthetic pigments and by increase in the levels of H2O2, lipid peroxidation and ion leakage. In conclusion, modulation of antioxidant system in a coordinated manner in response to Cd accumulation appears to help plants tolerate toxicity of Cd up to 5 μM. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2008.
Effect of long‐term exposure to simazine on brain and muscle acetylcholinesterase activity of common carp (Cyprinus carpio)
Authors: Oropesa A. L. , García Cambero J. P. , Soler F.
Published: January 2008

Several water‐contamination incidents with simazine have occurred in the province of Badajoz (Spain), due to its excessive use for controlling weeds in olive trees and vineyards. Simazine residues were also detected in drinking water, increasing public health concern. However, little is known on the effects that low levels of simazine pose to environment organisms. We investigated if residues of simazine in the natural waters would affect brain and muscle acetylcholinesterase activity in common carps captured in areas in which simazine residues were detected at average levels of 4.5 μg/L. Results confirmed depression on brain and muscle acetylcholinesterase activity of 20% and 29%, respectively, in carps inhabiting one of the simazine‐contaminated ponds, termed “Molinos de Matachel.” To assess the biological significance of this finding, we developed a controlled laboratory study in which carps were exposed to simazine at 45 μg/L (10‐fold that of the natural water levels) for 90 days. The results obtained in the field study were not confirmed in our laboratory experiment, since carps did not show evidence or brain or muscle acetylcholinesterase activity depression for the duration of the experiment, and therefore, we can conclude that acetylcholinesterase depression found in carps collected in “Molinos de Matachel” should be ascribed to other compounds or mixtures of xenobiotics. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2008.
Interaction of bisphenol a with human UDP‐glucuronosyltransferase 1A6 enzyme
Authors: Hanioka Nobumitsu , Takeda Yuri , Tanaka‐Kagawa Toshiko , Hayashi Keiko , Jinno Hideto , Narimatsu Shizuo
Published: January 2008

The effects of bisphenol A (BPA) on UDP‐glucuronosyltransferase 1A6 (UGT1A6) activities in microsomes from human livers and yeast cells expressing human UGT1A6 (humUGT1A6) were investigated. Serotonin (5‐HT) and 4‐methylumbelliferone (4‐MU) were used as the substrates for UGT1A6. BPA dose‐dependently inhibited 5‐HT and 4‐MU glucuronidation activities in both enzyme sources. The IC50 values of BPA for 5‐HT and 4‐MU glucuronidation activities were 156 and 163 μM for liver microsomes, and 84.6 and 80.3 μM for yeast cell microsomes expressing humUGT1A6, respectively. The inhibitory pattern of BPA for 5‐HT and 4‐MU glucuronidation activities in human liver microsomes exhibited a mixture of competitive and noncompetitive components, with Ki values of 84.9 and 72.3 μM, respectively. In yeast cell microsomes expressing humUGT1A6, 5‐HT glucuronidation activities were noncompetitively inhibited by BPA (Ki value, 65.5 μM), whereas the inhibition of 4‐MU glucuronidation activities by BPA exhibited the mixed type (Ki value, 42.5 μM). These results suggest that BPA interacts with human UGT1A6 enzyme, and that the interaction may contribute to the toxicity, such as hormone disruption and reproductive effects, of BPA. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2008.
In vitro assessment of clastogenicity of mobile‐phone radiation (835 MHz) using the alkaline comet assay and chromosomal aberration test
Authors: Kim Ji‐Young , Hong Sae‐Yong , Lee Young‐Mi , Yu Shin‐Ae , Koh Woo Suk , Hong Joong‐Rak , Son Taeho , Chang Sung‐Keun , Lee Michael
Published: January 2008

Recently we demonstrated that 835‐MHz radiofrequency radiation electromagnetic fields (RF‐EMF) neither affected the reverse mutation frequency nor accelerated DNA degradation in vitro. Here, two kinds of cytogenetic endpoints were further investigated on mammalian cells exposed to 835‐MHz RF‐EMF (the most widely used communication frequency band in Korean CDMA mobile phone networks) alone and in combination with model clastogens: in vitro alkaline comet assay and in vitro chromosome aberration (CA) test. No direct cytogenetic effect of 835‐MHz RF‐EMF was found in the in vitro CA test. The combined exposure of the cells to RF‐EMF in the presence of ethylmethanesulfonate (EMS) revealed a weak and insignificant cytogenetic effect when compared to cells exposed to EMS alone in CA test. Also, the comet assay results to evaluate the ability of RF‐EMF alone to damage DNA were nearly negative, although showing a small increase in tail moment. However, the applied RF‐EMF had potentiation effect in comet assay when administered in combination with model clastogens (cyclophosphamide or 4‐nitroquinoline 1‐oxide). Thus, our results imply that we cannot confidently exclude any possibility of an increased risk of genetic damage, with important implications for the possible health effects of exposure to 835‐MHz electromagnetic fields. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2008.
Comparative study of bioconcentration and EROD activity induction in the Japanese flounder, red sea bream, and Java medaka exposed to polycyclic aromatic hydrocarbons
Authors: Cheikyula J. Orkuma , Koyama Jiro , Uno Seiichi
Published: January 2008

Japanese flounder (Paralichthys olivaceus), red sea bream (Pagrus major), and Java medaka (Oryzias javanicus) were exposed to water borne polycyclic aromatic hydrocarbons (PAHs) for 10 days to compare PAH bioconcentration and P450 enzyme induction by ethoxyresorufin‐O‐deethylase (EROD) activity for use in oil spill biomonitoring in Asian waters. Target exposure concentration for phenanthrene, pyrene, and chrysene were 30 μg/L each, while benzo[a]pyrene was 3.0 μg/L. Phenanthrene and pyrene were accumulated in the flounder and red sea bream; chrysene was found only in the livers of the red sea bream, while Java medaka accumulated the high molecular weight benzo[a]pyrene along with the other PAHs. Total PAH concentrations increased with duration of exposure in the red sea bream from 184 ± 37 ng/g wet weight (w.w.) in day 2 to 572 ± 72 ng/g (w.w.) in day 10; It, however, decreased in the other two species. Among the three fish species, Java medaka had the highest initial total PAH concentration of 388 ± 62 ng/g (w.w.); this was, however, reduced to the lowest final concentration of 52.3 ± 3 ng/g (w.w.). It also had the highest EROD activity of 4.2 ± 2.8 n mol/min/mg protein compared to the lowest of 0.11 ± 0.03 n mol/min/mg protein in the Japanese flounder. Java medaka with high EROD activity induction and bioaccumulation of all PAHs will be suitable for PAH biomonitoring in Asian waters. Due to its high PAH bioconcentration red sea bream is also recommended for consideration for biomonitoring and PAH chronic toxicity tests. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2008.
Alteration of proteins expression in apoptotic FL cells induced by MCLR
Authors: Xing Ming‐Luan , Wang Xiao‐Feng , Xu Li‐Hong
Published: January 2008

Microcystins (MCs) are a family of monocyclic heptapeptide hepatotoxins produced by freshwater species of cyanobacteria. Microcystin‐LR (MCLR) is the most frequently studied and most toxic in over 80 MC congeners. Great deals of studies have demonstrated that MCLR can induce apoptosis in a wide variety of cell types. Although much evidence indicates that mitochondria play a pivotal role in MCLR‐induced apoptosis, the complicated apoptosis mechanisms induced by MCLR have not been completely characterized. It is possible that there are other apoptotic pathways existing in MCLR‐induced apoptosis. The present study was undertaken to determine the expression of PP2A, CHOP, Bax, Bcl‐2, and p53 proteins in MCLR‐induced apoptosis in FL cells. The results showed that MCLR could induce apoptosis in FL cells and the process was accompanied with the upregulation of PP2A, Bax, and p53 proteins and the downregulation of Bcl‐2 proteins. In addition, the CHOP protein was upregulated at most treatment groups and decreased at the highest concentration group. These results, especially the alteration of PP2A and CHOP proteins might provide new insights into MCLR‐induced apoptosis. © 2008 Wiley Periodicals, Inc. Environ Toxicol 2008.
Response of antioxidant enzymes, ascorbate and glutathione metabolism towards cadmium in hyperaccumulator and nonhyperaccumulator ecotypes of Sedum alfredii H.
Authors: Jin Xiaofen , Yang Xiaoe , Mahmood Qaisar , Islam Ejazul , Liu Dan , Li Hong
Published: January 2008

Hydroponics studies were conducted to investigate the antioxidant adaptations, ascorbate and glutathione metabolism in hyperaccumulating ecotype of Sedum alfredii (HE) exposed to high Cd environment, when compared with its nonhyperaccumulating ecotype (NHE). Exposure to Cd induced a burst of oxidative stress in both ecotypes which was evident by the sharp increase in hydrogen peroxide (H2O2) contents and lipid peroxidation. Buthionine sulfoximine (BSO), an inhibitor of glutathione (GSH) synthesis, did not affect H2O2 concentrations as well as growth of both ecotypes in the absence of Cd. However, compared with Cd application alone, BSO combined with Cd treatment caused a substantial augmentation of H2O2 accumulation accompanied by a reduction in Cd concentrations in roots and leaves of HE at the end of treatment, which may rule out the possibility that GSH biosynthesis may play an important role as a signal of the stress regulation. No efficient and superior enzymatic antioxidant defense mechanisms against Cd‐imposed oxidative stress existed in both NHE and HE, but the essential nonenzymatic components like ascorbic acid (AsA) and GSH played a prominent role in tolerance against Cd. Cadmium stimulated a notable rise in AsA concentration in both ecotypes soon after the application of treatment. A preferential Cd‐stress response in HE was suggested to changes in the GSH pool, where acclimation was marked by increased GSH concentrations. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2008.
Inhibitory Effects of Cholesterol Derivatives on DNA Polymerase and Topoisomerase Activities, and Human Cancer Cell Growth
Authors: Ishimaru Chisato , Yonezawa Yuko , Kuriyama Isoko , Nishida Masayuki , Yoshida Hiromi , Mizushina Yoshiyuki
Published: January 2008

This paper describes the inhibitory activities of cholesterol derivatives such as cholesterol, sodium cholesteryl sulfate, cholesteryl‐5α, 6α‐epoxide, cholesteryl chloride, cholesteryl bromide, and cholesteryl hemisuccinate (compounds1–6, respectively) against DNA polymerase (pol), DNA topoisomerase (topo), and human cancer cell growth. Among the compounds tested, compounds2and6revealed themselves to be potent inhibitors of animal pols, and the IC50values for pols were 0.84–11.6 and 2.9–148 μM, respectively. Compounds2,3and6inhibited the activity of human topo II, with IC50values of 5.0, 12.5 and 120 μM, respectively. Compounds2,3and6also suppressed human cancer cell (promyelocytic leukemia cell line, HL‐60) growth, and LD50values were 8.8, 20.2 and 72.3 μM, respectively, suggesting that cell growth inhibition had the same tendency as the inhibition of topos rather than pols. Compounds2and6arrested the cells in S and G2/M phases, compound3arrested the cells in the G2/M phase, and these compounds also increased sub‐G1 phase in the cell cycle. These results suggested that the effect of cell cycle arrest might be effective on both pols and topos activities. From these findings, the action mode of cholesterol derivatives as anti‐cancer compounds is discussed.
Mosses of sub-Antarctic Heard Island: an updated list and discussion of their distribution
Authors: Selkirk P.M. , Whinam J.P. , Downing A.J. , Skotnicki M.L.
Published: January 2008

During an early summer visit in 2000, mosses were collected from sites around Heard Island. Three species, Bryoerythrophyllum recurvirostrum (Hedw.) P.C.Chen, Philonotis cf. tenuis (Taylor) Reichardt and Syntrichia filaris (Müll.Hall) R.H. Zander have been added to the list of moss species known from the island, bringing the total to 40 moss taxa. Syntrichia anderssonii (abcngström) R.H. Zander was found with sporophytes, whereas previously its sporophytes were known in the sub-Antarctic only from Macquarie Island. Extensions of range on Heard Island have been recorded for several species. There are few geographical differences in species composition between locations around the island, provided appropriate habitats exist.
Recent advances in understanding Antarctic climate evolution
Authors: Siegert Martin J. , Barrett Peter , DeConto Robert , Dunbar Robert , Ó Cofaigh Colm , Passchier Sandra , Naish Tim
Published: January 2008

Geological evidence shows that the ice sheet and climate in Antarctica has changed considerably since the onset of glaciation around 34 million years ago. By analysing this evidence, important information concerning processes responsible for ice sheet growth and decay can be determined, which is vital for appreciating future changes in Antarctica. Geological records are diverse and their analyses require a variety of techniques. They are, however, essential for the establishment of hypotheses regarding past Antarctic changes. Numerical models of ice and climate are useful for testing such hypotheses, and in recent years there have been several advances in our knowledge relating to ice sheet history gained from these tests. This paper documents five case studies, employing a full range of techniques, to exemplify recent insights into Antarctic climate evolution from modelling ice sheet inception in the earliest Oligocene to quantifying Neogene ice sheet fluctuations and process-led investigations of recent (last glacial) changes.
Predicting aggressive behavior in the third year from infant reactivity and regulation as moderated by maternal behavior
Authors: Crockenberg Susan C. , Leerkes Esther M. , BÁrrig JÓ Patricia S.
Published: January 2008

The degree to which infant attention behaviors, together with infant reactivity to frustrating events, predict aggressive behavior at 2.5 years, and the moderating effect of maternal behavior were tested with 64 low-risk mothers and infants. Mothers rated infant negative reactivity at 5 months and aggressive behavior and maternal trait anger at 2.5 years; infant and maternal behaviors were observed at 6 months. Based on hierarchical multiple regressions, infantattention tofrustrating events at 6 months positively predicted aggressive behavior, whereaslooking away fromfrustrating events was associated with less aggressive behavior for girls only. High reactivity to limits predicted aggressive behavior only when mothers encouraged infant attentiontothe frustrating event, suggesting that maternal behavior amplifies developmental pathways associated with infant temperament.
Do maternal attention-deficit/hyperactivity disorder symptoms exacerbate or ameliorate the negative effect of child attention-deficit/hyperactivity disorder symptoms on parenting?
Authors: Psychogiou Lamprini , Daley Dave M. , Thompson Margaret J. , Sonuga-Barke Edmund J. S.
Published: January 2008

The impact of similarity in parent and child characteristics on the quality of parenting is underresearched. The current study examined the interaction between mother and child attention-deficit/hyperactivity disorder (ADHD) symptoms on parenting. Two hypotheses were tested: the similarity-fit hypothesis, which predicted that parent and child similarity will improve parenting, and the similarity-misfit hypothesis, which predicted the opposite. Study 1 examined the associations between maternal and child ADHD symptoms and child-specific rearing attitudes of 95 mothers with school-aged children. In Study 2 this analysis was extended to more objective observer-rated mother–child interaction and maternal expressed emotion in 192 mothers of preschool children. Child ADHD symptoms were associated with negative maternal comments and maternal ADHD symptoms with negative expressed emotion. In both studies maternal ADHD symptoms appeared to ameliorate the effects of child ADHD symptoms on negative parenting. Parental response to children with high ADHD symptoms was more positive and affectionate when the mother also had high ADHD symptoms. The results support the similarity-fit hypothesis and highlight the importance of considering both child and maternal ADHD symptoms in studies of parenting.
Smoking during pregnancy and offspring externalizing problems: An exploration of genetic and environmental confounds
Authors: D'Onofrio Brian M. , Hulle Carol A. van , Waldman Irwin D. , Rodgers Joseph Lee , Harden K. Paige , Rathouz Paul J. , Lahey Benjamin B.
Published: January 2008

Previous studies have documented that smoking during pregnancy (SDP) is associated with offspring externalizing problems, even when measured covariates were used to control for possible confounds. However, the association may be because of nonmeasured environmental and genetic factors that increase risk for offspring externalizing problems. The current project used the National Longitudinal Survey of Youth and their children, ages 4–10 years, to explore the relations between SDP and offspring conduct problems (CPs), oppositional defiant problems (ODPs), and attention-deficit/hyperactivity problems (ADHPs) using methodological and statistical controls for confounds. When offspring were compared to their own siblings who differed in their exposure to prenatal nicotine, there was no effect of SDP on offspring CP and ODP. This suggests that SDP does not have a causal effect on offspring CP and ODP. There was a small association between SDP and ADHP, consistent with a causal effect of SDP, but the magnitude of the association was greatly reduced by methodological and statistical controls. Genetically informed analyses suggest that unmeasured environmental variables influencing both SDP and offspring externalizing behaviors account for the previously observed associations. That is, the current analyses imply that important unidentified environmental factors account for the association between SDP and offspring externalizing problems, not teratogenic effects of SDP.
Relations between recurrent trauma exposure and recent life stress and salivary cortisol among children
Authors: Bevans Katherine , Cerbone Arleen , Overstreet Stacy
Published: January 2008

The present study evaluated the independent and cumulative effects of recent life stress, previous trauma, and recent trauma exposure on salivary cortisol levels among school-aged children. Sixty-eight children (mean age = 10.7 years) reported their exposure to life stressors and traumatic events in the 12 months preceding the study. Children and their caregivers reported frequency of exposure to trauma earlier in life. Exposure to life stress within the past 12 months was related to higher afternoon cortisol levels. Exposure to high levels of recent trauma in combination with frequent exposure to trauma earlier in life was related to both lower morning cortisol levels and higher afternoon cortisol levels. Results suggest that frequency, duration, and severity of exposure to stress and trauma played key roles in the prediction of basal cortisol levels in a community sample of urban youth.
Immune evasion by pathogens of bovine respiratory disease complex
Authors: Srikumaran Subramaniam , Kelling Clayton L. , Ambagala Aruna
Published: January 2008

Bovine respiratory tract disease is a multi-factorial disease complex involving several viruses and bacteria. Viruses that play prominent roles in causing the bovine respiratory disease complex include bovine herpesvirus-1, bovine respiratory syncytial virus, bovine viral diarrhea virus and parinfluenza-3 virus. Bacteria that play prominent roles in this disease complex areMannheimia haemolyticaandMycoplasma bovis. Other bacteria that infect the bovine respiratory tract of cattle areHistophilus(Haemophilus)somniandPasteurella multocida. Frequently, severe respiratory tract disease in cattle is associated with concurrent infections of these pathogens. Like other pathogens, the viral and bacterial pathogens of this disease complex have co-evolved with their hosts over millions of years. As much as the hosts have diversified and fine-tuned the components of their immune system, the pathogens have also evolved diverse and sophisticated strategies to evade the host immune responses. These pathogens have developed intricate mechanisms to thwart both the innate and adaptive arms of the immune responses of their hosts. This review presents an overview of the strategies by which the pathogens suppress host immune responses, as well as the strategies by which the pathogens modify themselves or their locations in the host to evade host immune responses. These immune evasion strategies likely contribute to the failure of currently-available vaccines to provide complete protection to cattle against these pathogens.
Mycoplasma bovispneumonia in cattle
Authors: Caswell Jeff L. , Archambault Marie
Published: January 2008

Mycoplasma bovisis an important and emerging cause of respiratory disease and arthritis in feedlot cattle and young dairy and veal calves, and has a variety of other disease manifestations in cattle.M. bovisis certainly capable of causing acute respiratory disease in cattle, yet the attributable fraction has been difficult to estimate. In contrast,M. bovisis more accepted as a cause of chronic bronchopneumonia with caseous and perhaps coagulative necrosis, characterized by persistent infection that seems poorly responsive to many antibiotics. An understanding of the disease has been recently advanced by comparisons of natural and experimentally induced disease, development of molecular diagnostic tools, and understanding some aspects of virulence, yet uncertainties regarding protective immunity, the importance of genotypic diversity, mechanisms of virulence, and the role of co-pathogens have restricted our understanding of pathogenesis and our ability to effectively control the disease. This review critically considers the relationship betweenM. bovisinfection and the various manifestations of the bovine respiratory disease complex, and addresses the pathogenesis, clinical and pathologic sequelae, laboratory diagnosis and control of disease resulting fromM. bovisinfection in the bovine respiratory tract.
The path‐density distribution of oceanic surface‐to‐surface transport
Authors: Holzer Mark , Primeau François W.
Published: January 2008

A novel diagnostic for advective‐diffusive surface‐to‐surface paths is developed and applied to a global ocean model. The diagnostic provides, for the first time, a rigorous quantitative assessment of the great ocean conveyor's deep branch. A new picture emerges of a diffusive conveyor in which the deep North Pacific is a holding pen of long‐residence‐time water. Our diagnostic is the joint density, η, per unit volume and interior residence time, τ, of paths connecting two specified surface patches. The spatially integrated η determines the residence‐time partitioned flux and volume of water in transit from entry to exit patch. We focus on interbasin paths from high‐latitude water mass formation regions to key regions of re‐exposure to the atmosphere. For non‐overlapping patches, a characteristic timescale is provided by the residence time, τϕ, for which the associated flux distribution, ϕ, has its maximum. Paths that are fast compared to τϕ are organized by the major current systems, while paths that are slow compared to τϕ are dominated by eddy diffusion. Because ϕ has substantial weight in its tail for τ > τϕ, the fast paths account for only a minority of the formation‐to‐re‐exposure flux. This conclusion is expected to apply to the real ocean based on recent tracer data analyses, which point to long eddy‐diffusive tails in the ocean's transit‐time distributions. The long‐τ asymptotic path density is governed by two time‐invariant patterns. One pattern, which we call the Deep North Pacific pattern, ultimately dominates a secondary redistribution pattern.
Semiannual variability in temperature and salinity observed by Triangle Trans‐Ocean Buoy Network (TRITON) buoys in the eastern tropical Indian Ocean
Authors: Hase Hideaki , Masumoto Yukio , Kuroda Yoshifumi , Mizuno Keisuke
Published: January 2008

The time series of temperature and salinity obtained by Triangle Trans‐Ocean Buoy Network buoys in the eastern Indian Ocean was used to investigate the characteristics of their variations and possible mechanisms of the semiannual ocean variability. Spectral analysis indicates that the dominant temperature signals in the surface layer and below the thermocline have intraseasonal and semiannual timescales, respectively. The semiannual isotherm deepening in the thermocline appears clearly during the monsoon transition periods, and indicates the vertical phase shift below the thermocline. The characteristic speed of the wave estimated from the vertical phase shift corresponds to a value between the characteristic speeds of the second and third baroclinic modes. The correlation between the zonal surface wind stress on the equator and the depth of 20°C isotherm variation shows that the forcing region of the semiannual isotherm variation is located around 68°E to 78°E longitude. The estimation of characteristic speed from the lag between these variations also shows a value between the second and third vertical‐mode gravity waves. The salinity variations also indicate that the intraseasonal and semiannual signals are dominant in the surface layer and the thermocline, respectively. The appearance of salty water around the upper thermocline lags the subsurface zonal current variation by about 45 days on the semiannual timescale, suggesting the advection of salty water by the subsurface currents along the equator. There is a possibility that the contact between the subsurface salty water and surface fresh water results in the formation of a barrier layer in the eastern basin.
Distribution of icebergs in the Atlantic and Indian ocean sectors of the Antarctic region and its possible links with ENSO
Authors: Romanov Yury A. , Romanova Nina A. , Romanov Peter
Published: January 2008

The spatial distribution and multiyear variability of iceberg concentration in the Atlantic and Indian ocean sectors of the Antarctic region have been studied using ship‐borne observations of iceberg occurrence. The collected dataset includes more than 40,000 reports predominantly from Russian and Australian research vessels made over the last 36 years (1970–2005). The analysis of the data has revealed a gradual decrease in the iceberg concentration away from the coast of Antarctica and a substantial variation along the coast line. Large concentration of icebergs was found in the Weddell Sea and north‐east of the Antarctic Peninsula. Several regions in the Atlantic and Indian Ocean sector of Antarctica have been identified where yearly anomalies of the iceberg occurrence exhibit a noticeable correlation with El Niňo/Southern Oscillation (ENSO) events. The strongest ENSO effect was observed in the region east of Drake Passage where the iceberg concentration increased by about 50% during years of the negative Southern Oscillation Index (SOI) phase. The change in the iceberg amount is explained by an increased iceberg drift into this region from the southern part of Weddell Sea and from Pacific Ocean. The latter is caused by anomalous surface pressure High and associated anti‐clockwise circulation around the pressure anomaly developing in the south‐eastern part of Pacific Ocean during the negative phase of ENSO.
Long‐term sunspot forcing of savanna structure inferred from carbon and oxygen isotopes
Authors: Woodborne Stephan , Mélice Jean‐Luc , Scholes Robert J.
Published: January 2008

We used the δ18O and δ13C isotopes from a speleothem and Δ14C values from known age tree rings as proxies for vegetation structure, rainfall and sunspot activity over the last 10,000 years. The δ18O and δ13C signals are significantly correlated and wavelet coherence analysis shows that a phase locked responses is only found to occur over periods less than 150 years. The δ13C and Δ14C signals are also significantly correlated but the wavelet coherence analysis shows phase locked responses at periods in the order of 320 and 1100 years at various times in the past. We conclude that savanna vegetation structure responds to rainfall over periods of decades to about 150 years, and to solar forcing over periods greater than 150 years. We propose that elevated UV‐B radiation at the earth surface during periods of low sunspot activity favours the productivity of C4 plants over C3 plants possibly because of the metabolic cost of structural adaptive responses and of producing UV‐B absorbing compounds in the latter.
Mass unloading along the inner edge of the Enceladus plasma torus
Authors: Farrell W. M. , Kaiser M. L. , Gurnett D. A. , Kurth W. S. , Persoon A. M. , Wahlund J. E. , Canu P.
Published: January 2008

A major discovery made by the Cassini spacecraft at Saturn was the substantial mass ejection from the south pole of Enceladus. Previous studies show that this ejected gas can become ionized and subsequently load mass onto the connecting magnetic field lines near the moon. Radial diffusion then allows the mass‐loaded field lines to move outward to ∼15 Rs and inward to ∼2 Rs, forming a plasma torus. We demonstrate herein that the mass is also “unloaded” along the inner edge of this plasma torus ‐ the edge incident with the plasma‐absorbing A‐ring. Interpreting down‐drifting z‐mode tones from active sites along the inner edge of the ion torus as emission near the local electron plasma frequency, fpe, we can remotely‐monitor this reduction in plasma density along the torus inner edge as a function time. We find that the down‐drift of the z‐mode tones corresponds typically to a plasma density change dn/dt ∼ −5 × 10−4/cm3‐s and when integrated over an annulus defined by the outer edge of the A‐ring, corresponds to a mass loss of ∼ 40 kg/s. Using the z‐mode tones, we also find locations where plasma mass from the ring‐ionosphere is possibly loaded at 1–2 kg/s onto field lines near the Cassini gap.
A model for late Quaternary methane ice core signals: Wetlands versus a shallow marine source
Authors: O'Hara Kieran D.
Published: January 2008

A three‐reservoir model with first order kinetics for methane records in the Vostok (Antarctica) and GISP2 (Greenland) ice cores reproduces the sawtooth pattern and the maximum and minimum concentrations. The model also returns an atmospheric methane relaxation time of ∼10 years for both cores, which is the same as current estimates. The characteristics of the source reservoirs are long relaxation times (33.3 and 100 ky) and high initial methane concentrations (2500 and 7000 ppm) for GISP2 and Vostok, respectively. These characteristics are consistent with gas hydrate sources in shallow marine sediments, but not with wetland sources which have insufficient storage capacity and low source strength.
Orientation of the HAARP ELF ionospheric dipole and the auroral electrojet
Authors: Cohen M. B. , Gołkowski M. , Inan U. S.
Published: January 2008

The HF heating facility of the High Frequency Active Auroral Research Program (HAARP), located near Gakona, Alaska, generates ELF (300 Hz ‐ 3 kHz) waves via modulated HF (2.7–10 MHz) heating of the auroral electrojet. Using two ELF/VLF receivers at ∼700 km from HAARP, the orientation of the equivalent ELF radiating ionospheric dipole is inferred from the relative strength and Earth‐ionosphere waveguide modal content of signals received. In several cases analyzed the effective HAARP electric dipole orientation is generally along magnetic east‐west direction. A new metric is introduced to evaluate the validity of the determination of source characteristics with medium and long‐range ELF/VLF measurements. Results are put into context of the auroral electrojet, indicating the possibility of studying small‐scale electrojet structure not observable with magnetometers.