bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamic evolution of selenocysteine utilization in bacteria: a balance between selenoprotein loss and evolution of selenocysteine from redox active cysteine residues
Authors: Zhang Yan , Romero Hector , Salinas Gustavo , Gladyshev Vadim N
Published: October 2006

Background

Selenocysteine (Sec) is co-translationally inserted into protein in response to UGA codons. It occurs in oxidoreductase active sites and often is catalytically superior to cysteine (Cys). However, Sec is used very selectively in proteins and organisms. The wide distribution of Sec and its restricted use have not been explained.

Results

We conducted comparative genomics and phylogenetic analyses to examine dynamics of Sec decoding in bacteria at both selenium utilization trait and selenoproteome levels. These searches revealed that 21.5% of sequenced bacteria utilize Sec, their selenoproteomes have 1 to 31 selenoproteins, and selenoprotein-rich organisms are mostly Deltaproteobacteria or Firmicutes/Clostridia. Evolutionary histories of selenoproteins suggest that Cys-to-Sec replacement is a general trend for most selenoproteins. In contrast, only a small number of Sec-to-Cys replacements were detected, and these were mostly restricted to formate dehydrogenase and selenophosphate synthetase families. In addition, specific selenoprotein gene losses were observed in many sister genomes. Thus, the Sec/Cys replacements were mostly unidirectional, and increased utilization of Sec by existing protein families was counterbalanced by loss of selenoprotein genes or entire selenoproteomes. Lateral transfers of the Sec trait were an additional factor, and we describe the first example of selenoprotein gene transfer between archaea and bacteria. Finally, oxygen requirement and optimal growth temperature were identified as environmental factors that correlate with changes in Sec utilization.

Conclusion

Our data reveal a dynamic balance between selenoprotein origin and loss, and may account for the discrepancy between catalytic advantages provided by Sec and the observed low number of selenoprotein families and Sec-utilizing organisms.
Macrophages in experimental rat lung isografts and allografts: infiltration and proliferation in situ
Authors: Schmidt Andree , Sucke Jochen , Fuchs-Moll Gabriele , Freitag Petra , Hirschburger Markus , Kaufmann Andreas , Garn Holger , Padberg Winfried , Grau Veronika
Published: October 2006

Alveolar macrophages (AMs) and peribronchial/perivascular macrophages are probably involved in lung allograft damage. We investigate leukocyte infiltration into graft tissue and address the question whether proliferation in situ contributes to macrophage homeostasis and accumulation. Lung transplantation was performed in the Lewis (LEW)-to-LEW and in the Dark Agouti-to-LEW rat strain combination. Graft infiltration by ED1+ and ED2+ (CD163) macrophages was analyzed by immunohistochemistry (IHC) and compared with infiltration by lymphocytes. Cells in the S-phase of the cell cycle were pulse-labeled with BrdU and detected immunohistochemically. Finally, the donor or recipient origin of AMs was determined by IHC and in situ hybridization. ED1+ AMs in allogeneic transplants increased by more than 25-fold from Days 1 to 5. In addition, large, peribronchial/perivascular infiltrates developed containing numerous ED1+ cells. Although AMs in normal rat lungs are CD163−, AMs up-regulated CD163 between Days 4 and 5, reaching maximum values on Day 6. Lymphocytes were less numerous than macrophages. About 16% of the AMs and 10% of the peribronchial/perivascular macrophages were in the S-phase of the cell cycle on Day 2 post-transplantation. No differences in the frequency of BrdU+ macrophages were obvious between isografts and allografts. AMs of donor origin increased in number considerably during allograft rejection. In conclusion, the cellular infiltrate in lung allografts is dominated by macrophages, which exhibit an unusual phenotype and a strong capacity for mitotic self-renewal.
Bone Loss and Increased Bone Adiposity in Spontaneous and Pharmacologically Induced Diabetic Mice
Authors: Botolin Sergiu , McCabe Laura R.
Published: October 2006

Insulin-dependent diabetes mellitus (IDDM) is associated with increased risk of osteopenia/osteoporosis in humans. The mechanisms accounting for diabetic bone loss remain unclear. Pharmacologic inducers of IDDM, such as streptozotocin, mimic key aspects of diabetes in rodents, allow analysis at the onset of diabetes, and induce diabetes in genetically modified mice. However, side effects of streptozotocin, unrelated to diabetes, can complicate data interpretation. The nonobese diabetic (NOD) mouse model develops diabetes spontaneously without external influences, negating side effects of inducing agents. Unfortunately, in this model the onset of diabetes is unpredictable, occurs in a minority of male mice, and can only be studied in a single mouse strain. To validate the relevance of the more flexible streptozotocin-induced diabetes model for studying diabetes-associated bone loss, we compared its phenotype to the spontaneously diabetic NOD model. Both models exhibited hyperglycemia and loss of body, fat pad, and muscle weight. Furthermore, these genetically different and distinct models of diabetes induction demonstrated similar bone phenotypes marked by significant trabecular bone loss and increased bone marrow adiposity. Correspondingly, both diabetic models exhibited decreased osteocalcin mRNA and increased adipocyte fatty acid-binding protein 2 mRNA levels in isolated tibias and calvaria. Taken together, multiple streptozotocin injection-induced diabetes is a valid model for understanding the acute and chronic pathophysiologic responses to diabetes and their mechanisms in bone.
A novel single amino acid change in small subunit ribosomal protein S5 has profound effects on translational fidelity
Authors: Kirthi Narayanaswamy , Roy-Chaudhuri Biswajoy , Kelley Teresa , Culver Gloria M.
Published: October 2006

S5 is a small subunit ribosomal protein (r-protein) linked to the functional center of the 30S ribosomal subunit. In this study we have identified a unique amino acid mutation in Escherichia coli S5 that produces spectinomycin-resistance and cold sensitivity. This mutation significantly alters cell growth, folding of 16S ribosomal RNA, and translational fidelity. While translation initiation is not affected, both +1 and −1 frameshifting and nonsense suppression are greatly enhanced in the mutant strain. Interestingly, this S5 ribosome ambiguity-like mutation is spatially remote from previously identified S5 ribosome ambiguity (ram) mutations. This suggests that the mechanism responsible for ram phenotypes in the novel mutant strain is possibly distinct from those proposed for other known S5 (and S4) ram mutants. This study highlights the importance of S5 in ribosome function and cell physiology, and suggests that translational fidelity can be regulated in multiple ways.
Incorporation and Clearance of Omega-3 Fatty Acids in Erythrocyte Membranes and Plasma Phospholipids
Authors: Cao Jing , Schwichtenberg Kerry A , Hanson Naomi Q , Tsai Michael Y
Published: October 2006

Background: The sum of eicosapentaenoic acid (EPA, 20:5 ω3) and docosahexaenoic acid (DHA, 22:6 ω3) in erythrocyte membranes, termed the omega-3 index, can indicate suboptimal intake of omega-3 fatty acids, a risk factor for cardiovascular disease (CVD). To study the effects of fatty acid supplementation, we investigated the rate of incorporation and clearance of these fatty acids in erythrocyte membranes and plasma after intake of supplements.

Methods: Twenty study participants received supplementation with either fish oil (1296 mg EPA + 864 mg DHA/day) or flaxseed oil (3510 mg alpha-linolenic acid + 900 mg linoleic acid/day) for 8 weeks. We obtained erythrocyte membrane and plasma samples at weeks 0, 4, 8, 10, 12, 14, 16, and 24 and extracted and analyzed fatty acids by gas chromatography.

Results: After 8 weeks of fish oil supplementation, erythrocyte membrane EPA and DHA increased 300% (P <0.001) and 42% (P <0.001), respectively. The mean erythrocyte omega-3 index reached a near optimal value of 7.8%, and remained relatively high until week 12. EPA and DHA showed greater increases and more rapid washout period decreases in plasma phospholipids than in erythrocyte membranes. Flaxseed oil supplementation increased erythrocyte membrane EPA to 133% (P <0.05) and docosapentaenoic acid (DPA, 22:5 ω3) to 120% (P <0.01) of baseline, but DHA was unchanged. In plasma phospholipids, EPA, DPA, and DHA showed a slight but statistically insignificant increase.

Conclusions: Erythrocyte membrane EPA+DHA increases during relatively short intervals in response to supplementation at rates related to amount of supplementation. These results may be useful to establish appropriate dosage for omega-3 fatty acid supplementation.
Rapid and Simultaneous Quantification of 4 Urinary Proteins by Piezoelectric Quartz Crystal Microbalance Immunosensor Array
Authors: Luo Yang , Chen Ming , Wen Qianjun , Zhao Meng , Zhang Bo , Li Xiaoyan , Wang Feng , Huang Qing , Yao Chunyan , Jiang Tianlun , Cai Guoru , Fu Weiling
Published: October 2006

Background: Urinary proteins are predictive and prognostic markers for diabetes nephropathy. Conventional methods for the quantification of urinary proteins, however, are time-consuming, and most require radioactive labeling. We designed a label-free piezoelectric quartz crystal microbalance (QCM) immunosensor array to simultaneously quantify 4 urinary proteins.

Methods: We constructed a 2 × 5 model piezoelectric immunosensor array fabricated with disposable quartz crystals for quantification of microalbumin, α1-microglobulin, β2-microglobulin, and IgG in urine. We made calibration curves after immobilization of antibodies at an optimal concentration and then evaluated the performance characteristics of the immunosensor with a series of tests. In addition, we measured 124 urine samples with both QCM immunosensor array and immunonephelometry to assess the correlation between the 2 methods.

Results: With the QCM immunosensor array, we were able to quantify 4 urinary proteins within 15 min. This method had an analytical interval of 0.01–60 mg/L. The intraassay and interassay imprecisions (CVs) were <10%, and the relative recovery rates were 90.3%–109.1%. Nonspecificity of the immunosensor was insignificant (frequency shifts <20 Hz). ROC analyses indicated sensitivities were ≥95.8% and, specificities were ≥76.3%. Bland–Altman difference plots showed the immunosensor array to be highly comparable to immunonephelometry.

Conclusions: The QCM system we designed has the advantages of being rapid, label free, and highly sensitive and thus can be a useful supplement to commercial assay methods in clinical chemistry.
Factors Influencing the Effectiveness of Relationship Marketing: A Meta-Analysis
Authors: Palmatier Robert W. , Dant Rajiv P. , Grewal Dhruv , Evans Kenneth R.
Published: October 2006

Relationship marketing (RM) has emerged as one of the dominant mantras in business strategy circles, though RM investigations often yield mixed results. To help managers and researchers improve the effectiveness of their efforts, the authors synthesize RM empirical research in a meta-analytic framework. Although the fundamental premise that RM positively affects performance is well supported, many of the authors’ findings have significant implications for research and practice. Relationship investment has a large, direct effect on seller objective performance, which implies that additional meditated pathways may explain the impact of RM on performance. Objective performance is influenced most by relationship quality (a composite measure of relationship strength) and least by commitment. The results also suggest that RM is more effective when relationships are more critical to customers (e.g., service offerings, channel exchanges, business markets) and when relationships are built with an individual person rather than a selling firm (which partially explains the mixed effects between RM and performance reported in previous studies).
The Unhealthy = Tasty Intuition and Its Effects on Taste Inferences, Enjoyment, and Choice of Food Products
Authors: Raghunathan Rajagopal , Naylor Rebecca Walker , Hoyer Wayne D.
Published: October 2006

Across four experiments, the authors find that when information pertaining to the assessment of the healthiness of food items is provided, the less healthy the item is portrayed to be, (1) the better is its inferred taste, (2) the more it is enjoyed during actual consumption, and (3) the greater is the preference for it in choice tasks when a hedonic goal is more (versus less) salient. The authors obtain these effects both among consumers who report that they believe that healthiness and tastiness are negatively correlated and, to a lesser degree, among those who do not report such a belief. The authors also provide evidence that the association between the concepts of “unhealthy” and “tasty” operates at an implicit level. The authors discuss possibilities for controlling the effect of the unhealthy = tasty intuition (and its potential for causing negative health consequences), including controlling the volume of unhealthy but tasty food eaten, changing unhealthy foods to make them less unhealthy but still tasty, and providing consumers with better information about what constitutes “healthy.”
Broadening the Scope of Reference Price Advertising Research: A Field Study of Consumer Shopping Involvement
Authors: Howard Daniel J. , Kerin Roger A.
Published: October 2006

The current understanding of reference pricing requires broadening to reflect contemporary advertising practices and shopping behavior. A content analysis of 13,594 newspaper retail advertisements reveals that it is uncommon for reference pricing to be used alone in advertisements: 87.2% of the advertisements featuring reference pricing also include limited-time availability (i.e., “Three days only!”) or sale announcements in the headline or copy. Using dual-process theories of persuasion as a conceptual framework, the authors conduct three field experiments that compare the conditions under which the use of limited-time availability and sale announcements in advertisements that feature reference prices affects consumer price perceptions and store shopping intentions. The findings yield three insights for reference price advertising. First, reference pricing results in favorable price perceptions and store shopping intentions only when consumers are shopping for a product. Second, when consumers are shopping for a product, reference pricing paired with limited-time availability results in more favorable price perceptions and store shopping intentions than the use of either technique alone. Third, the use of sale announcements and limited-time availability in reference price advertisements has a favorable effect on price perceptions and store shopping intentions when consumers are not shopping for a product.
The Role of Relational Embeddedness in Retail Buyers' Selection of New Products
Authors: Kaufman Peter , Jayachandran Satish , Rose Randall L.
Published: October 2006

Retailers face considerable risk in introducing new products because of high failure rates. Given the proliferation of new products juxtaposed against finite shelf space, retail buyers are confronted with a choice problem. To enhance understanding of this issue, the authors examine the role of buyer-salesperson and firm-firm relationships using data collected in the context of actual new product selection by retail buyers at two large grocery retailers in the United States. The findings indicate that buyer-salesperson and firm-firm relationships have a greater influence on new product acceptance when a new product's attractiveness is modest than when the new product is very unattractive or very attractive. At modest levels of product attractiveness, the likelihood of new product acceptance can increase by as much as 60% when the buyer has a strong relationship with the salesperson. The study provides insights into the complex interplay of marketing relationships and product attractiveness in retail buyers' selection of new products.
Can “Low-Fat” Nutrition Labels Lead to Obesity?
Authors: Wansink Brian , Chandon Pierre
Published: October 2006

In this era of increasing obesity and increasing threats of legislation and regulation of food marketing practices, regulatory agencies have pointedly asked how “low-fat” nutrition claims may influence food consumption. The authors develop and test a framework that contends that low-fat nutrition labels increase food intake by (1) increasing perceptions of the appropriate serving size and (2) decreasing consumption guilt. Three studies show that low-fat labels lead all consumers—particularly those who are overweight—to overeat snack foods. Furthermore, salient objective serving-size information (e.g., “Contains 2 Servings”) reduces overeating among guilt-prone, normal-weight consumers but not among overweight consumers. With consumer welfare and corporate profitability in mind, the authors suggest win-win packaging and labeling insights for public policy officials and food marketers.
Time-Varying Effects of Chronic Hedonic Goals on Impulsive Behavior
Authors: Ramanathan Suresh , Menon Geeta
Published: October 2006

Marketers and academics have long been interested in understanding what drives impulsive behavior and have focused on what causes a person to indulge. The three experiments reported in this article examine reasons that underlie urges that strengthen over time and cause people to overindulge from a goal-theoretic view of impulsiveness. The authors demonstrate that impulsivity is characterized by generalized reward sensitivity and by an activation of chronic goals to seek pleasure in various domains (Experiment 1). Furthermore, through a moment-to-moment tracking of desires, the authors demonstrate that such chronic goals, particularly in conjunction with temporarily primed goals, provide the momentum for impulsive people to override their self-control goals, leading to a strengthening of desires over time (Experiment 2). In turn, this causes impulsive people to behave even more impulsively when their activated hedonic goals are not satiated (Experiment 3). The findings suggest that contextual cues have powerful influences on impulsive behavior over time when acting in conjunction with chronic hedonic goals. The results have public policy implications for behaviors such as binge drinking and unrestrained eating.
The Neglect of Prescreening Information
Authors: Chakravarti Amitav , Janiszewski Chris , Ülkümen Gülden
Published: October 2006

Several studies show that information used to screen alternatives becomes less important than information acquired later in the search process simply because it was used to screen. Experiment 1 shows that the tendency to deemphasize prescreening information leads to systematically different choices for decision makers who screen alternatives compared with decision makers who do not screen alternatives. Additional studies show that screening encourages decision makers to shift their emphasis from prescreening information to postscreening information (Experiment 2). Prescreening information is deemphasized because of the categorization that occurs when people create a consideration set of retained alternatives (Experiments 3 and 4). Together, the results show that a brand's strength of consideration (i.e., how highly an option ranks on screening criteria) may have little influence on the likelihood of it being chosen in a postscreening choice process.
An Empirical Two-Stage Choice Model with Varying Decision Rules Applied to Internet Clickstream Data
Authors: Moe Wendy W.
Published: October 2006

In this article, the author proposes and applies an empirical two-stage choice model to Internet clickstream data that captures observed choices for two choice stages: products viewed and products purchased. The model allows for interdependences between choices within a stage as well as the use of varying decision rules in each stage. The author accommodates heterogeneity in preferences and in decision rules. The proposed model uses observed choices to infer both attribute preference ratings and criterion attributes. The results show empirically, in a field setting, that the product attributes evaluated in Stage 1 differ from those evaluated in Stage 2. Consistent with existing theory, consumers tend to use simpler decision rules based on a subset of attribute information in earlier stages. The author also finds some preliminary evidence that attributes such as price and size tend to be considered in only one of the two stages, whereas ingredient attributes tend to be considered in both stages. From a managerial perspective, the identification of criterion attributes, coupled with the preference parameters estimated by the model, can assist with the targeting and positioning of promotional strategies.
The Association of Job Strain with Coronary Heart Disease and Metabolic Syndrome in Municipal Workers in Turkey
Authors: Demiral Yucel , Soysal Ahmet , Bilgin Ahmet Can , Kılıç Bulent , Unal Belgin , Uçku Reyhan , Theorell Tores
Published: October 2006

The Association of Job Strain with Coronary Heart Disease and Metabolic Syndrome in Municipal Workers in Turkey: Yucel Demiral, et al. Department of Public Health, Dokuz Eylül University School of Medicine, Turkey—To explore the association of job strain with CHD and metabolic syndrome in municipal workers. A cross‐sectional study was completed of 450 male workers. Coronary heart disease was defined as: physician diagnosed ischemic heart disease; and/or, ischemic findings in the ECG. Metabolic syndrome was defined according to the criterion set by the National Cholesterol Education Panel. The demand‐control model was used to assess job strain. Self administered questionnaires were completed after a face to face interview. Logistic regression models were constructed to assess the association of job strain with CHD and metabolic syndrome. The prevalence of metabolic syndrome and CHD were 17.8% and 8.0% respectively. Both CHD and metabolic syndrome were found to be significantly higher in higher income groups. Job demand and job control were not found to be associated with either CHD or metabolic syndrome. Metabolic syndrome was significantly more prevalent among the high job strain workers, but the significance was lost when controlled for age. The findings suggest that there is no significant association between job strain and metabolic syndrome and CHD in this sample of Turkish workers. Job strain may possibly be perceived differently in different cultures and occupations. Future studies may benefit from using a combination of different stress models and more diverse study populations.
The Impact of Sociodemographic Factors vs. Gender Roles on Female Hospital Workers' Health: Do We Need to Shift Emphasis?
Authors: Musshauser Doris , Bader Angelika , Wildt Beatrice , Hochleitner Margarethe
Published: October 2006

The Impact of Sociodemographic Factors vs. Gender Roles on Female Hospital Workers' Health: Do We Need to Shift Emphasis?: Doris Musshauser, et al. Ludwig Boltzmann Institute for Gender Studies, Austria—The aim of the present study was to evaluate the physical and mental health status of female workers from five different occupational groups and to identify possible sociodemographic and gender‐coded family‐related factors as well as work characteristics influencing women's health. The identified predictors of health status were subjected to a gender‐sensitive analysis and their relations to one another are discussed. A total of 1083 female hospital workers including medical doctors, technical and administrative personnel, nurses and a group mainly consisting of scientific personnel and psychologists completed a questionnaire measuring work‐ and family‐related variables, sociodemographic data and the Short‐form 36 Health Questionnaire (SF‐36). Data were analysed by multivariate regression analyses. Female medical doctors reported highest scores for all physical health dimensions except General Health. Our study population showed general low mental health status among administrative personnel and the heterogeneous group, others, scored highest on all mental health component scores. A series of eight regression analyses were performed. Three variables contributed highly significantly to all SF‐36 subscale scores: age, satisfaction with work schedule, and the unpaid work variable. Age had the strongest influence on all physical dimensions except General Health (β=– 0.17) and had no detectable influence on mental health scores. The unpaid work variable (β=–0.23; p<0.001) exerted a stronger influence on General Health than did age. Nevertheless, these variables were limited predictors of physical and mental health status. In all occupational groups the amount of time spent daily on child care and household tasks, as a traditional gender‐coded factor, and satisfaction with work schedule were the only contributors to mental health among working women in this study. Traditional sociodemographic data had no effect on mental health status. In addition to age, these factors were shown to be the only predictors of physical health status of female workers. Gender‐coded‐factors matter. These findings underline the importance of including gender‐coded family‐ and work‐related variables in medical research over and above basic sociodemographic data in order to describe study populations more clearly.
Continuation of Smoking Cessation and Following Weight Change after Intervention in a Healthy Population with High Smoking Prevalence
Authors: Kadowaki Takashi , Watanabe Makoto , Okayama Akira , Hishida Kayoko , Okamura Tomonori , Miyamatsu Naomi , Hayakawa Takehito , Kita Yoshikuni , Ueshima Hirotsugu
Published: October 2006

Continuation of Smoking Cessation and Following Weight Change after Intervention in a Healthy Population with High Smoking Prevalence: Takashi Kadowaki, et al. Department of Health Science, Shiga University of Medical Science—Smoking prevalence among males is conspicuously high in Asian countries including Japan. There are few prospective intervention studies on the duration of smoking cessation within regions with a high prevalence of smokers, such as Asia. We investigated the extent to which subjects continued abstaining from smoking after receiving smoking cessation support provided for all smokers in an occupational setting, regardless of their willingness to quit smoking. The subjects were 251 male workers who were smokers and had received a smoking cessation intervention in 1997 in an occupational setting. Smoking cessation rates and body mass index (BMI) at 10, 18, 30, 42, 54, and 66 months after the initial intervention were confirmed during annual health check‐ups. Those who quit smoking following the intervention and continuously abstained from smoking throughout the study period were separately examined for BMI. After five years, 10.6% of the smokers continued smoking cessation. Of the abstainers who quit following the intervention, the abstinence rate decreased in the first and second year, but it stabilized at approximately 45% after the third year. High nicotine dependence and a self‐reported lack of willingness to quit smoking did not lower long‐term abstinence rates. Abstainers initially gained 1.55 BMI on average, but decreased the weight gain to 0.96 BMI over six years. Introducing smoking cessation support without nicotine replacement therapy is an effective long‐term strategy in a healthy population with a high smoking prevalence. Abstainers maintain their smoking cessation if they refrain from smoking for three years.
Visual Problems among Electronic and Jewelry Workers in Thailand
Authors: Untimanon Orrapan , Pacharatrakul Wanpen , Boonmeepong Kowit , Thammagarun Ladda , Laemun Nuttapong , Taptagaporn Sasitorn , Chongsuvivatwong Virasakdi
Published: October 2006

Visual Problems among Electronic and Jewelry Workers in Thailand: Orrapan Untimanon, et al. Bureau of Occupational and Environmental Diseases, Department of Disease Control, Ministry of Public Health, Thailand—In the processes of electronic and jewelry manufacturing, workers are employed to use their skill in tiny visual tasks (1–3 mm) and near visual distances (<35 cm) that cause visual strain. This study consisted of 3 phases: 1) a survey of workers visual health status and factors affecting their visual strain; 2) the development and implementation of guidelines in the selected factories; and 3) a resurvey to document the change. The baseline survey was conducted in Samutprakan Province during October to December, 2003. Ninetyfive percent of the sampled workers were female with an average age of 26.2 yr. Fifty‐two percent of the workers had at least one kind of vision problem that might have affected their work performance, and 48.3% of the work sites had substandard illumination levels. The intervention included improvement of lighting conditions, the introduction of short breaks, and correction of visual performance problems. After the intervention, the inadequate lighting problem went down to 24.5%. All factories took a rest break and 20.5% of the workers with inadequate visual performance had corrected their vision in the intervention period. Comparing pre‐intervention status with the end of the program, the Critical Fusion Frequency (CFF) at one hour and two hours of work were improved with statistical significance among the electronic but not the jewelry workers. In conclusion, visual problems among vision intensive industrial workers are common. Intervention programs partially but significantly improved the situation.
Efeito de exsudatos radiculares em endósporos de Pasteuria penetrans e em juvenis do segundo estádio de Meloidogyne incognita
Authors: Rocha Fernando da Silva , Campos Vicente P. , Souza Ricardo Magela de
Published: October 2006

Juvenis do segundo estádio (J2) de Meloidogyne incognita foram incubados nos exsudatos radiculares de soja (Glycine max), tomateiro (Lycopersicon esculentum), cafeeiro (Coffea arabica), feijoeiro (Phaseolus vulgaris), mostarda (Brassica rapa), Crotalaria juncea e C. spectabilis e em água por 12 h. Em seguida, realizou-se o teste de adesão por centrifugação ou por borbulhamento. Em outro ensaio, endósporos de Pasteuria penetrans foram incubados por quatro dias a 26 ºC nos exsudatos e submetidos à adesão em J2 de M. incognita, sob borbulhamento constante por 24 h em tubos contendo água. Os J2 com endósporos aderidos pelo teste de borbulhamento foram inoculados em mudas de tomateiro. Verificou-se que a incubação dos J2 por 12 h nos exsudatos radiculares testados reduziu o número de endósporos de P. penetrans por J2 independentemente do método de adesão empregado. Os J2 incubados nos exsudatos radiculares testados proporcionaram menor número de fêmeas parasitadas em tomateiro em relação à testemunha (água), bem como menor número de galhas com exceção dos J2 incubados em exsudato do próprio tomateiro. A reprodução dos J2 incubados nos exsudatos radiculares não foi afetada quando comparada à testemunha. A incubação dos endósporos nos exsudatos das plantas testadas reduziu a adesão e a infetividade em J2, em relação à testemunha. Após 28 dias da inoculação, observou-se redução no número de fêmeas parasitadas resultantes da infecção desses J2 com endósporos incubados em exsudatos radiculares comparada com aqueles incubados em água. O parasitismo do J2 com endósporos tratados com exsudatos radiculares e a reprodutividade de fêmeas oriundas da infetividade desses J2 foram semelhantes aos incubados em água.
Distinct features of Pepper yellow mosaic virus isolates from tomato and sweetpepper
Authors: Cunha Luis C. V. da , Resende Renato de O. , Nagata Tatsuya , Inoue-Nagata Alice K.
Published: October 2006

Determination of virus diversity in the field is vital to support a sustainable breeding program for virus resistance of horticultural crops. The present study aimed to characterize four field potyvirus isolates found naturally infecting sweet pepper (Capsicum annuum) (Sa66 and Sa115) and tomato (Lycopersicon esculentum) (IAC3 and Sa21) plants. Their biological characteristics revealed differences among the isolates in their ability to infect distinct Capsicum spp. and tomato genotypes, and in the severity of symptoms caused by these isolates compared to the infection caused by an isolate of Pepper yellow mosaic virus (PepYMV). Absence of cross-reaction was found among the studied isolates with antiserum against Potato virus Y (PVY). However, all isolates reacted, at different intensities, with antiserum against PepYMV. All isolates showed high identity percentage (97 to 99%) of the amino acid sequence of the coat protein with PepYMV (accession AF348610) and low (69 to 80%) with other potyvirus species. The comparison of the 3' untranslated region also confirmed this finding with 97 to 98% identity with PepYMV, and of 47 to 71% with other potyviruses. The results showed that PepYMV isolates were easily differentiated from PVY by serology and that the host response of each isolate could be variable. In addition, the nucleotide sequence of the coat protein and 3' untranslated region was highly conserved among the isolates.
Pratylenchus brachyurus em Cucumis melo no Brasil
Authors: Torres Gustavo R. C. , Pedrosa Elvira M. R. , Siqueira Kércya M. S. , Moura Romero M.
Published: October 2006

Este é o primeiro assinalamento de Pratylenchus brachyurus em meloeiro (Cucumis melo) ocorrendo em condições naturais de campo no Brasil, no Pólo Açu-Mossoró, RN. São apresentados dados morfométricos da população encontrada.
Caracterização de um isolado do Pepper mild mottle virus que não quebra a resistência do gene L3 em Capsicum sp.
Authors: Eiras Marcelo , Chaves Alexandre L. R. , Moreira Silvia R. , Araujo Jansen de , Colariccio Addolorata
Published: October 2006

Sementes de pimenta (Capsicum baccatum) 'Dedo de Moça' destinadas ao plantio comercial e adquiridas no município de São Paulo, SP, analisadas quanto à presença de vírus, por meio de testes biológicos e sorológicos revelaram-se infetadas por uma estirpe do Pepper mild mottle virus (PMMoV). Para confirmar a identidade do isolado, promoveu-se a RT-PCR com oligonucleotídeos que flanqueiam a ORF da capa protéica de espécies do gênero Tobamovirus do subgrupo 1. Os fragmentos de DNA amplificados, quando seqüenciados e comparados com outros isolados de tobamovírus depositados no GenBank, apresentaram valores de identidade de nucleotídeos entre 94 e 100% com outras seqüências de PMMoV, inferiores a 75% para as demais espécies de tobamovírus do subgrupo I (Tobacco mosaic virus, Tomato mosaic virus e Odontoglossum ringspot virus) e 65% para os tobamovírus dos subgrupos II e III. O PMMoV-BR revelou 100% de identidade com isolados japoneses, sugerindo que este patógeno pode ter sido introduzido daquele país. A seqüência de aminoácidos deduzidos da capa protéica indicou também, que este isolado não é capaz de quebrar a resistência do gene L3 de Capsicum spp. Fato confirmado pelos sintomas causados nas hospedeiras diferenciais de Capsicum spp., verificando-se que este isolado não foi capaz de infetar plantas de C. chinense (L3) e C. chacoense (L4). Estes resultados confirmaram a importância da caracterização dos isolados de tobamovírus, fundamental para adequação de medidas de controle, principalmente, prevenindo a entrada e posterior disseminação do patógeno em novas áreas de cultivo.
Quantitative analysis of two important epidemiological features of the common bean: Phaeoisariopsis griseola pathosystem
Authors: Willocquet Laetitia , Allorent Delphine , Savary Serge
Published: October 2006

This work quantifies two important epidemiological features of the bean (Phaseolus vulgaris)/Phaeoisariopsis griseola pathosystem. The first is the effect of the number of nights of leaf wetness on infection efficiency. Infection efficiency was below 10% when inoculated leaflets were exposed to less than two nights of leaf wetness. Optimum infection efficiencies were obtained after three to four nights of leaf wetness, at about 50%. Further nights of leaf wetness did not increase the infection efficiency. The second feature quantified is the relative rate of leaflet defoliation for varying levels of angular leaf spot severity. It increased with disease severity according to a logarithm-like curve, and a relative rate of 0.23 day-1 was estimated for a severity of 18%. The implications of these results on the disease epidemiology are discussed.
An integrated approach to assess water quality and environmental contamination in the fluvial-lagoon system of the Palizada River, Mexico
Authors: Osten Jaime Rendón-Von , Memije Martin G. , Ortiz Alejandro , Soares Amadeu M.V.M. , Guilhermino Lucia
Published: October 2006

Water quality and the contamination in relation to land use in the fluvial-lagoon system of the Palizada River (FLSPR; State of Campeche, Mexico) was investigated using an integrated approach including 21-d in situ bioassays with the native mosquito fish Gambusia yucatana, determination of cholinesterase (ChE) activity in wild populations of this species, and water-quality variables. The present study was performed over 19 months at three sites with different types of anthropogenic impact. Significant differences in a water-quality index for aquatic life (WQI) were found among sites. Fish mortality was significantly and negatively correlated with WQI, dissolved oxygen, and sulfates. High survival rates (≥80%) were found in preliminary exposures and in some of the bioassays performed at all sites. Therefore, test chambers and the cabinet seemed to be suitable for use in toxicity bioassays with G. yucatana. The in situ bioassay was able to discriminate levels of water contamination in both time and space, indicating that it is suitable for use in conditions similar to those found in the FLSPR. In the biomonitoring study, a ChE inhibition of greater than 20% in wild fish was found in some periods of the year at all sampling sites. This indicates the presence of anticholinesterase agents in the water. Fish from two of the sites had a ChE inhibition of greater than 40% in some sampling months, suggesting that deleterious effects already may have been induced in fish. Furthermore, at these sites, the pattern of ChE inhibition was in good agreement with the probable runoff of pesticides from agricultural fields.
Cadmium exposures during early development: DO they lead to reproductive impairment in fathead minnows?
Authors: Sellin Marlo K. , Kolok Alan S.
Published: October 2006

The primary objective of this study was to determine whether cadmium (Cd) exposures during embryonic and larval development alter the reproductive performance, reproductive physiology, and sex ratio of fathead minnows (Pimephales promelas). Embryonic exposures were conducted by exposing adult female fathead minnows to 0, 25, or 100 μg/L Cd for 8 d prior to breeding. Larval exposures were conducted by exposing the larvae to waterborne Cd at 0, 12.5, 25, or 50 μg/L from 8 to 29 d posthatch (the time period associated with female sexual differentiation). Minnows from each exposure period were raised to maturity, at which time their reproductive success, secondary sexual characteristics, gonadosomatic index (GSI), plasma 11-ketotestosterone (11-KT) concentrations, and sex ratios were assessed. Results from the embryonic study reveal that Cd exposures alter the secondary sexual characteristics of male fathead minnows but do not alter reproductive performance, GSI, 11-KT concentrations, or sex ratios. Larval exposures, during the period of female sexual differentiation, significantly reduce the frequency of adult spawning and increase clutch size but do not alter fecundity, secondary sexual characteristics, GSI, or 11-KT. Subtle alterations in sex ratio were observed, indicating that larval Cd exposures may increase the proportion of females in an exposed population.
Metamorphosis increases biotransformation of polychlorinated biphenyls: A comparative study of polychlorinated biphenyl metabolism in green frogs (Rana clamitans) and leopard frogs (Rana pipiens) at various life stages
Authors: Leney Jocelyn L. , Drouillard Ken G. , Haffner G. Douglas
Published: October 2006

Polychlorinated biphenyl (PCB) elimination rates were used to determine whether green frogs (Rana clamitans) and leopard frogs (Rana pipiens) at three life stages (tadpole, metamorph, and adult) were capable of metabolic biotransformation of PCBs. Polychlorinated biphenyls were grouped according to their structural properties to determine whether congeners with specific structures were eliminated more rapidly than others, which would suggest the occurrence of metabolic biotransformation. For both species and at all life stages studied, PCBs with adjacent unsubstituted meta-para sites (group-2 PCBs) were eliminated significantly faster than PCBs with adjacent unsubstituted ortho-meta sites (group-3 PCBs). Because these groups of PCBs span similar hydrophobicity ranges, it was concluded that green and leopard frogs can selectively metabolize group-2 PCBs. Metabolic activity was more pronounced in the metamorph stage than in any other life stage. In green frog metamorphs, the average elimination rate of the group-2 PCBs was 4.9-fold greater than that of the group-3 PCBs. By contrast, in green frog tadpoles, group-2 PCBs were eliminated 1.9-fold faster than group-3 PCBs, and in green frog adults, group-2 PCBs were eliminated 1.5-fold faster than group-3 PCBs.
Dynamics of 17α-Ethynylestradiol exposure in rainbow trout (Oncorhynchus mykiss): Absorption, tissue distribution, and hepatic gene expression pattern
Authors: Skillman Ann D. , Nagler James J. , Hook Sharon E. , Small Jack A. , Schultz Irvin R.
Published: October 2006

17α-Ethynylestradiol (EE2) is a synthetic estrogen identified in sewage effluents. To understand better the absorption kinetics of EE2 and the induction of vitellogenin (VTG) and estrogen receptor α (ERα) mRNA, we subjected male rainbow trout (Onchorynchus mykiss) to continuous water exposures of 125 ng/L of EE2 for up to 61 d. Trout were either repetitively sampled for blood plasma or serially killed at selected time intervals. Vitellogenin, ERα mRNA, and EE2 were measured using enzymelinked immunosorbent assay and using quantitative polymerase chain reaction and gas chromatography–mass spectrometry, respectively. In separate experiments, trout were exposed to EE2 for 7 d, and hepatic gene expression was assessed using a low- and high-density cDNA microarray. The EE2 was rapidly absorbed by the trout, with an apparent equilibrium at 16 h in plasma and liver. The ERα mRNA levels also increased rapidly, reaching near-peak levels by 48 h. In contrast, plasma levels of VTG continuously increased for 19 d. After 61 d, tissues with the highest levels of VTG were the liver, kidney, and testes. Microarray-based gene expression studies provided unexpected results. In some cases, known estrogen-responsive genes (e.g., ERα) were unresponsive, whereas many of the genes that have no apparent link to estrogen function or EE2 toxicity were significantly altered in expression. Of the two microarray approaches tested in the present study, the high-density array appeared to be superior because of the improved quality of the hybridization signal and the robustness of the response in terms of the number of genes identified as being EE2 responsive.
Multilevel evaluation of nonylphenol toxicity in fourth-instar larvae ofChironomus riparius(Diptera, Chironomidae)
Authors: Lee Se-Bum , Choi Jinhee
Published: October 2006

The multilevel biomarker approach, wherein different biological responses ranging from molecular to physiological are evaluated, is essential to determine the general health status of an organism in pollutant biomonitoring programs. Furthermore, it permits extrapolation of the relationship between responses at different levels of biological organization. The aim of this study was to develop, under laboratory conditions, a multilevel biomarker approach for evaluating the toxicological response of nonylphenol (NP) in Chironoms riparius. To investigate the effect of NP on C. riparius, an acute toxicity test was performed measuring 24-h median lethal concentration. Responses on molecular, biochemical, and physiological levels were subsequently investigated on sublethal exposure. To assess molecular-level effects, we investigated DNA damage and the expression of heat shock protein 70 (HSP70) gene, whereas biochemical-level responses were determined by investigation of various enzymes activities. Growth and development were investigated as physiological-level responses. The biomarkers found to be most sensitive to NP treatment were HSP70 gene expression and DNA strand break. After having been studied with lower concentration levels with longer exposure period, these biomarkers could be considered early warning signs of exposure to low concentrations of chemical exposure. Statistically significant correlations were observed between DNA damage and the development descriptor; however, a mechanistic study appears to be necessary to establish causal relationships. This approach could be applied in environmental biomonitoring programs, and the data obtained from this study should constitute an important contribution to knowledge of the toxicology of NP in C. riparius, about which little data is available.
Bioavailability of polycyclic aromatic hydrocarbons in field-contaminated Anacostia River (Washington, DC) sediment
Authors: Lu Xiaoxia , Reible Danny D. , Fleeger John W.
Published: October 2006

Sediment–water partitioning behavior and bioavailability of five polycyclic aromatic hydrocarbons (PAHs; phenanthrene, pyrene, chrysene, benzo[k]fluoranthene, and benzo[a]pyrene) were measured in field-contaminated sediment collected from moderately polluted regions of the Anacostia River (Washington, DC, USA). Much of the sediment PAH burden was resistant to desorption: Effective partition coefficients were 2- to 10-fold greater than expected from literature values, and more than 80% of PAHs remained sorbed after treatment of the sediment with a nonionic polymeric adsorbent (Amberlite XAD-2) for 20 h. Bioaccumulation, elimination, and assimilation of each PAH in the deposit-feeding tubificid oligochaete Ilyodrilus templetoni were measured and compared with the equivalent measurements from laboratory-inoculated sediment. Ilyodrilus templetoni effectively accessed the desorption-resistant fraction of these organic contaminants, as exhibited by high single-gut passage assimilation efficiencies (ASEs) of the five PAHs (60% < ASE < 90%). However, steady-state accumulations of PAHs by I. templetoni were very low and consistent with low pore-water concentrations. The present results suggest that steady-state accumulation of PAHs is controlled by pore-water concentrations and is not necessarily related to route of uptake or assimilation efficiencies.