Is there a causal association between genotoxicity and the imposex effect?

There is a growing body of evidence that indicates common environmental pollutants are capable of disrupting reproductive and developmental processes by interfering with the actions of endogenous hormones. Many reports of endocrine disruption describe changes in the normal development of organs and tissues that are consistent with genetic damage, and recent studies confirm that many chemicals classified to have hormone-modulating effects also possess carcinogenic and mutagenic potential. To date, however, there have been no conclusive examples linking genetic damage with perturbation of endocrine function and adverse effects in vivo. Here, we provide the first evidence of DNA damage associated with the development of imposex (the masculinization of female gastropods considered to be the result of alterations to endocrine-mediated pathways) in the dog-whelk Nucella lapillus. Animals (n = 257) that displayed various stages of tributyltin (TBT)-induced imposex were collected from sites in southwest England, and their imposex status was determined by physical examination. Linear regression analysis revealed a very strong relationship (correlation coefficient of 0.935, p < 0.0001) between the degree of imposex and the extent of DNA damage (micronucleus formation) in hemocytes. Moreover, histological examination of a larger number of dog-whelks collected from sites throughout Europe confirmed the presence of hyperplastic growths, primarily on the vas deferens and penis in both TBT-exposed male snails and in females that exhibited imposex. A strong association was found between TBT body burden and the prevalence of abnormal growths, thereby providing compelling evidence to support the hypothesis that environmental chemicals that affect reproductive processes do so partly through DNA damage pathways

Bayesian inference on major loci in related multigeneration selection lines of laying hens

A mixed inheritance model, postulating a polygenic effect and differences between the 3 genotypes of a biallelic locus, was fitted separately to the data of 2 multigeneration selection lines and a control evolving from a common base population. Inferences about the model were drawn from the application of the Gibbs sampler. Body weight at 20 and 40 wk (BW20, BW40) and average egg weight to 40 wk (EW40) were included in the analyses. Significance of differences between posterior means of parameters was established by comparing their 95% highest probability density regions. Significant (P 0.05) differences of posterior means of any parameter could be observed between lines. No significant genotypic or polygenic selection response was found for BW40. On the contrary, both genetic responses were found significant for EW40 in the selected lines, but not in the control. No differences (P > 0.05) between lines could be observed for the derived frequencies of the allele causing the higher trait value and the frequencies of one homozygote and the heterozygote genotypes at the major locus. The detection of a major locus with relatively modest effect confirmed that this type of analysis with data from selected lines was indeed powerfu

Is There a Causal Association between Genotoxicity and the Imposex Effect?

There is a growing body of evidence that indicates common environmental pollutants are capable of disrupting reproductive and developmental processes by interfering with the actions of endogenous hormones. Many reports of endocrine disruption describe changes in the normal development of organs and tissues that are consistent with genetic damage, and recent studies confirm that many chemicals classified to have hormone-modulating effects also possess carcinogenic and mutagenic potential. To date, however, there have been no conclusive examples linking genetic damage with perturbation of endocrine function and adverse effects in vivo. Here, we provide the first evidence of DNA damage associated with the development of imposex (the masculinization of female gastropods considered to be the result of alterations to endocrine-mediated pathways) in the dog-whelk Nucella lapillus. Animals (n = 257) that displayed various stages of tributyltin (TBT)-induced imposex were collected from sites in southwest England, and their imposex status was determined by physical examination. Linear regression analysis revealed a very strong relationship (correlation coefficient of 0.935, p < 0.0001) between the degree of imposex and the extent of DNA damage (micronucleus formation) in hemocytes. Moreover, histological examination of a larger number of dog-whelks collected from sites throughout Europe confirmed the presence of hyperplastic growths, primarily on the vas deferens and penis in both TBT-exposed male snails and in females that exhibited imposex. A strong association was found between TBT body burden and the prevalence of abnormal growths, thereby providing compelling evidence to support the hypothesis that environmental chemicals that affect reproductive processes do so partly through DNA damage pathways

In-service Initial Teacher Education in the Learning and Skills Sector in England: Integrating Course and Workplace Learning

The aim of the paper is to advance understanding of in-service learning and skills sector trainee teachers’ learning and propose ways of improving their learning. A conceptual framework is developed by extending Billett’s (International Journal of Educational Research 47:232–240, 2008) conceptualisation of workplace learning, as a relationally interdependent process between the opportunities workplaces afford for activities and interactions and how individuals engage with these, to a third base of participation, the affordances of the initial teacher education course. Hager and Hodkinson’s (British Educational Research Journal 35:619–638, 2009) metaphor of ‘learning as becoming’ is used to conceptualise the ways trainees reconstruct learning in a continuous transactional process of boundary crossing between course and workplace. The findings of six longitudinal case studies of trainees’ development, and evidence from other studies, illustrate the complex interrelationships between LSS workplace affordances, course affordances and trainee characteristics and the ways in which trainees reconstruct learning in each setting. The experience of teaching and interacting with learners, interactions with colleagues, and access to workplace resources and training are important workplace affordances for learning. However, some trainees have limited access to these affordances. Teaching observations, course activities and experiences as a learner are significant course affordances. Trainees’ beliefs, prior experiences and dispositions vary and significantly influence their engagement with course and workplace affordances. It is proposed that better integration of course and workplace learning through guided participation in an intentional workplace curriculum and attention to the ways trainees choose to engage with this, together with the use of practical theorising has the potential to improve trainee learning

Health effects in fish of long-term exposure to effluents from wastewater treatment works

The effects of simple mixtures of chemicals, with similar mechanisms of action, can be predicted using the concentration addition model (CA). The ability of this model to predict the estrogenic effects of more complex mixtures such as effluent discharges, however, has yet to be established. Effluents from 43 U.K. wastewater treatment works were analyzed for the presence of the principal estrogenic chemical contaminants, estradiol, estrone, ethinylestradiol, and nonylphenol. The measured concentrations were used to predict the estrogenic activity of each effluent, employing the model of CA, based on the relative potencies of the individual chemicals in an in vitro recombinant yeast estrogen screen (rYES) and a short-term (14-day) in vivo rainbow trout vitellogenin induction assay. Based on the measured concentrations of the four chemicals in the effluents and their relative potencies in each assay, the calculated in vitro and in vivo responses compared well and ranged between 3.5 and 87 ng/L of estradiol equivalents (E2 EQ) for the different effluents. In the rYES, however, the measured E2 EQ concentrations in the effluents ranged between 0.65 and 43 ng E2 EQ/L, and they varied against those predicted by the CA model. Deviations in the estimation of the estrogenic potency of the effluents by the CA model, compared with the measured responses in the rYES, are likely to have resulted from inaccuracies associated with the measurement of the chemicals in the extracts derived from the complex effluents. Such deviations could also result as a consequence of interactions between chemicals present in the extracts that disrupted the activation of the estrogen response elements in the rYES. E2 EQ concentrations derived from the vitellogenic response in fathead minnows exposed to a series of effluent dilutions were highly comparable with the E2 EQ concentrations derived from assessments of the estrogenic potency of these dilutions in the rYES. Together these data support the use of bioassays for determining the estrogenic potency of WwTW effluents, and they highlight the associated problems for modeling approaches that are reliant on measured concentrations of estrogenic chemicals

Illness Schema Activation and the Effects of Illness Seasonality on Accessibility of Implicit Illness-Related Information

The Common-Sense Model (CSM) of illness self-regulation is a leading theoretical framework describing the process by which an individual recognizes that he or she is physically ill and subsequently attempts to manage that illness state. The CSM proposes that people possess schematically organized implicit cognitive representations of health threats comprising information about illness such as symptoms, causes, label, duration, consequences, and procedures for managing threat [1, 2, 3, 4]. The proposed function of these stored knowledge structures is to activate a self-regulation process that might protect or restore a state of well-being [5]. The CSM proposes that the schematic representation is centrally activated by detection of deviations from the normal functioning self (i.e., experienced symptoms). The identification of illness and the initiation of self-management attempts follow from the search for illness-relevant cognitive structures and the matching of the content of illness schema to the symptomatic experience. For example, a headache (a symptomatic deviation from normal somatic experience) might activate illness schemata containing the cognitive representation of “headache” such as “hangover,” “dehydration,” or “flu.” The matching of the symptom to a particular illness schema will follow from the search and match to other aspects of plausible illness representations, such as its probable cause or duration (timeline).Full Tex

Fredholmness of Toeplitz operators on the Fock space

The Fredholm property of Toeplitz operators on the $p$-Fock spaces $F_\alpha^p$ on $\mathbb{C}^n$ is studied. A general Fredholm criterion for arbitrary operators from the Toeplitz algebra $\mathcal{T}_{p,\alpha}$ on $F_\alpha^p$ in terms of the invertibility of limit operators is derived. This paper is based on previous work, which establishes corresponding results on the unit balls $\mathbb{B}^n$

Larger and More Prominent Graphic Health Warnings on Plain-Packaged Tobacco Products and Avoidant Responses in Current Smokers: a Qualitative Study

Background: The introduction of tobacco plain packaging legislation in Australia meant that all tobacco products were to be sold in plain dark-brown packaging with 75 % front-of-pack graphic health warnings and standardised font type and size for brand name and product variant. The change in the size and prominence of the warnings has been proposed as a reason for behaviour change in smokers in terms of increased intentions to quit and quit attempts. Purpose: The current research examined attitudes and beliefs of cigarette smokers toward the increased size and prominence of the warnings and effects on their behaviour. Method: Participants (N = 160) completed open-ended responses to questions on beliefs, attitudes and responses to plain packaging. Responses were subjected to inductive thematic content analysis for key themes. Results: Four themes emerged from the analysis: emotional response to packaging, scepticism of health warnings, warnings and cessation behaviour, and avoidant coping behaviours. Participants reported increased negative emotional responses to the packaging and made specific reference to the graphic health warnings. Some participants attempted to discredit the messages. Others reported increased intentions to quit or quitting attempts. There were pervasive reports of avoidant responses including covering or hiding the warnings. Conclusion: Consistent with theories of illness perceptions and coping, current findings indicate that the larger, prominent graphic health warnings on plain-packaged tobacco products had pervasive effects on threat perceptions and subsequent behavioural responses. While some of the reported responses were adaptive (e.g. attempts to quit), others were maladaptive (e.g. avoiding the warnings)

Weight-loss intervention using implementation intentions and mental imagery: A randomised control trial study protocol

Background: Overweight and obesity are major health problems worldwide. This protocol describes the HEALTHI (Healthy Eating and Active LifesTyle Health Intervention) Program, a 12-week randomised-controlled weight-loss intervention that adopts two theory-based intervention techniques, mental imagery and implementation intentions, a behaviour-change technique based on planning that have been shown to be effective in promoting health-behaviour change in previous research. The effectiveness of goal-reminder text messages to augment intervention effects will also be tested. The trial will determine the effects of a brief, low cost, theory-based weight-loss intervention to improve dietary intake and physical activity behaviour and facilitate weight-loss in overweight and obese individuals. Methods/Design: Overweight or obese participants will be randomly allocated to one of three conditions: (1) a psycho-education plus an implementation intentions and mental imagery condition; (2) a psycho-education plus an implementation intentions and mental imagery condition with text messages; or (3) a psycho-education control condition. The intervention will be delivered via video presentation to increase the intervention's applicability in multiple contexts and keep costs low. We hypothesise that the intervention conditions will lead to statistically-significant changes in the primary and secondary outcome variables measured at 6 and 12 weeks post-intervention relative to the psycho-education control condition after controlling for baseline values. The primary outcome variable will be body weight and secondary outcome variables will be biomedical (body mass, body fat percentage, muscle mass, waist-hip circumference ratio, systolic and diastolic blood pressure, low-density lipoprotein, high-density lipoprotein, total cholesterol, triglycerides, blood glucose and insulin levels), psychological (quality of life, motivation, risk perception, outcome expectancy, intention, action self-efficacy, maintenance self-efficacy, goal setting and planning), and behavioural (self-reported diet intake, and physical activity involvement) measures. We also expect the intervention condition augmented with text messages to lead to statistically significant differences in the primary and secondary outcome variables at the follow up periods after controlling for baseline values. Discussion: The planned trial will test the effectiveness of the theory-based HEALTHI program intervention to reduce weight and salient psychological, biomedical, and behavioural outcomes in overweight and obese adults. The study has been designed to maximise applicability to real world settings and could be integrated into existing weight management practices