Sex-dependent selection differentially shapes genetic variation on and off the guppy Y chromosome

Because selection is often sex-dependent, alleles can have positive effects on fitness in one sex and negative effects in the other, resulting in intralocus sexual conflict. Evolutionary theory predicts that intralocus sexual conflict can drive the evolution of sex limitation, sex-linkage, and sex chromosome differentiation. However, evidence that sex-dependent selection results in sex-linkage is limited. Here, we formally partition the contribution of Y-linked and non-Y-linked quantitative genetic variation in coloration, tail, and body size of male guppies (Poecilia reticulata)—traits previously implicated as sexually antagonistic. We show that these traits are strongly genetically correlated, both on and off the Y chromosome, but that these correlations differ in sign and magnitude between both parts of the genome. As predicted, variation in attractiveness was found to be associated with the Y-linked, rather than with the non-Y-linked component of genetic variation in male ornamentation. These findings show how the evolution of Y-linkage may be able to resolve sexual conflict. More generally, they provide unique insight into how sex-specific selection has the potential to differentially shape the genetic architecture of fitness traits across different parts of the genome.

Creatine transporter protein content, localization, and gene expression in rat skeletal muscle

The present study examined the gene expression and cellular localization of the creatine transporter (CreaT) protein in rat skeletal muscle. Soleus (SOL) and red (RG) and white gastrocnemius (WG) muscles were analyzed for CreaT mRNA, CreaT protein, and total creatine (TCr) content. Cellular location of the CreaT protein was visualized with immunohistochemical analysis of muscle cross sections. TCr was higher (P <= 0.05) in WG than in both RG and SOL, and was higher in RG than in SOL. Total CreaT protein content was greater (P <= 0.05) in SOL and RG than in WG. Two bands (55 and 70 kDa) of the CreaT protein were found in all muscle types. Both the 55-kDa (CreaT-55) and the 70-kDa (CreaT-70) bands were present in greater (P <= 0.05) amounts in SOL and RG than in WG. SOL and RG had a greater amount (P <= 0.05) of CreaT-55 than CreaT-70. Immunohistochemical analysis revealed that the CreaT was mainly associated with the sarcolemmal membrane in all muscle types. CreaT mRNA expression per microgram of total RNA was similar across the three muscle types. These data indicate that rat SOL and RG have an enhanced potential to transport Cr compared with WG, despite a higher TCr in the latter.

An incremental FP-growth web content mining and its application in preference identification

This paper presents a real application of Web-content mining using an incremental FP-Growth approach. We firstly restructure the semi-structured data retrieved from the web pages of Chinese car market to fit into the local database, and then employ an incremental algorithm to discover the association rules for the identification of car preference. To find more general regularities, a method of attribute-oriented induction is also utilized to find customer’s consumption preferences. Experimental results show some interesting consumption preference patterns that may be beneficial for the government in making policy to encourage and guide car consumption.

Body mass index and parent-reported self-estem in elementary school children: evidence for a causal relationship.

OBJECTIVE: To clarify relationships between body mass index (BMI) and self-esteem in young children at a population level. To assess whether low self-esteem precedes or follows development of overweight/obesity in children. DESIGN: Prospective cohort study in elementary schools throughout Victoria, Australia. Child BMI and self-esteem were measured in 1997 and 2000. SUBJECTS: Random sample of 1,157 children who were in the first 4 y of elementary school (aged 5-10 y) at baseline. MEASURES: BMI was calculated from measured height and weight, then transformed to z-scores. Children were classified as nonoverweight, overweight or obese based on international cut-points. Low child self-esteem was defined as a score below the 15th percentile on the self-esteem subscale of the parent-reported Child Health Questionnaire. RESULTS: Overweight/obese children had lower median self-esteem scores than nonoverweight children at both timepoints, especially at follow-up. After accounting for baseline self-esteem, higher baseline BMI z-score predicted poorer self-esteem at follow-up (P=0.008). After accounting for baseline BMI z-score, poorer baseline self-esteem did not predict higher BMI z-score at follow-up. While nonoverweight children with low baseline self-esteem were more likely to develop overweight/obesity (OR=2.1, 95% CI=1.2, 3.6), this accounted for only a small proportion of the incidence of overweight. CONCLUSIONS: Our data show an increasingly strong association between lower self-esteem and higher body mass across the elementary school years. Overweight/obesity precedes low self-esteem in many children, suggesting a causal relationship. This indicates that prevention and management strategies for childhood overweight/obesity need to begin early to minimise the impact on self-esteem.

An alternative perspective on relationships, loyalty and future store choice

The purpose of this research was to provide an alternative perspective for retailers to develop relationships and loyalty. This study suggests that traditional trust and commitment theories are somewhat imperfect in predicting future store choice. Through path modelling, we introduce two additional constructs of store functional loyalty and relationship worth. These constructs together with commitment are powerful predictors of future store choice. Furthermore, the study examines the antecedents of relationships, loyalty and future store choice. We conclude with new insights and practical suggestions for retailers to build relationships, loyalty and influence customers' future store choice.

Community school teacher education and the construction of pedagogical discourse in Papua New Guinea

Pedagogical discourse in Papua New Guinea (PNG) community schooling is mediated by a western styles education. The daily administration and organisation of school activity, graded teaching and learning, subject selection, content boundaries, teaching and assessment methods are all patterned after western schooling. This educational settlement is part of a legacy of German, British and Australian government and non-government colonialism that officially came to an end in 1975. Given the colonial heritage of schooling in PNG, this study is interested in exploring particular aspects of the degree of mutuality between local discourses and the discourses of a western styled pedagogy in post-colonial times, for the purpose of better informing community school teacher education practices. This research takes place at and in the vicinity of Madang Teachers College, a pre-service community school teachers college on the north coast of Papua New Guinea. The research was carried out in the context of the researcher’s employment as a contract lecturer in the English language Department between 1991-1993. As an in-situ study it was influenced by the roles of different participants and the circumstances in which data was gathered and constituted, data which was compatible with participants commitments to community school teacher education and community school teaching and learning. In the exploration of specific pedagogic practices different qualitative research approaches and perspectives were brought to bear in ways best suited to the circumstances of the practice. In this way analytical foci were more dictated by circumstances rather by design. The analytical approach is both a hermeneutic one where participants’ activities are ‘read like texts’, where what is said or written is interpreted against the background of other informing contexts and texts, to better understand how understandings and meanings are produced and circulated; and also a phenomenological one where participants’ perspectives are sought to better understand how pedagogical discursive formations are assimilated with the ‘self’. The effect of shifting between these approaches throughout the study is to build up a sense of co-authorship between researcher and participants in relation to particular aspects of the research. The research explores particular sites where pedagogic discourse is produced, re-produced, distributed, articulated, consumed and contested, and in doing so seeks to better understand what counts as pedagogical discourse. These are sites that are largely unexplored in these terms, in the academic literature on teacher education and community schooling in PNG. As such, they represent gaps in what is documented and understood about the nature of post-colonial pedagogy and teacher training. The first site is a grade two community school class involved in the teaching and early learning of English as the ‘official’ language of instruction. Here local discourses of solidarity and agreement are seen to be mobilised to make meaningful, what are for the teacher and children moments in their construction as post-colonial subjects. What in instructional terms may be seen as an English language lesson becomes, in the light of the research perspectives used, an exercise in the structuring of new social identities, relations and knowings, problematising autonomous views of teaching and learning. The second site explores this issue of autonomous (decontextualised) teaching and learning through an investigation of student teachers’ epistemological contextualisations of knowledge, teaching and learning. What is examined is the way such orientations are constructed in terms of ‘traditional’ and ‘modern’ epistemological and pedagogical alignments, and, in terms of differently conceived notions of community, in a problematisation of the notion of community schooling. The third and fourth sites examine reflective accounts of student teachers’ pedagogic practices, understandings and subjectivities as they confront the moral and political economies and cultural politics of schooling in School Experiences and Practicum contexts, and show how dominant behaviourist and ‘rational/autonomous’ conceptions of what counts as teaching and learning are problematised in the way some students teachers draw upon wider social discourses to construct a dialogue with learners. The final site is a return to the community school where the discourse of school reports through which teachers, children and parents are constructed as particular subjects of schooling, are explored. Here teachers report children’s progress over a four year period and parents write back in conforming, confronting and contesting ways, in the midst of the ongoing enculturation of their children. In this milieu, schooling is shown to be a provider of differentiated social qualifications rather than a socially just and relevant education. Each of the above-mentioned studies form part of a research and pedagogic interest in understanding the ‘disciplining’ effects of schooling upon teacher education, the particular consequences of those effects, what is embraces, resisted and hidden. Each of the above sites is informed by various ‘intertexts’. The use of intertexts is designed to provide a multiplicity of views, actions and voices while enhancing the process of cross-cultural reading through contextualising the studies in ways that reveal knowledges and practices which are often excluded in more conventional accounts of teaching and learning. This research represents a journey, but not an aimless one. It is one which reads the ideological messages of coherence, impartiality and moral soundness of western pedagogical discourse against the school experiences of student-teachers, teachers, children and parents, in post-colonial Papua New Guinea, and finds them lacking.

Children's content regulation and the 'obesity epidemic'

Some 30 years ago, Australia introduced the Children's Television Standards (CTS) with the twin goals of providing children with high-quality local programs and offering some protection from the perceived harms of television. The most recent review of the CTS occurred in the context of a decade of increasing international concern at rising levels of overweight and obesity, especially in very young children. Overlapping regulatory jurisdictions and co-regulatory frameworks complicate the process of addressing pressing issues of child health, while rapid changes to the media ecology have both extended the amount of programming for children and increased the economic challenges for producers. Our article begins with an overview of the conceptual shifts in priorities articulated in the CTS over time. Using the 2007-09 Review of the CTS as a case study, it then examines the role of research and stakeholder discourses in the CTS review process and critiques the effectiveness of existing regulatory regimes, both in providing access to dedicated children's content and in addressing the problem of escalating obesity levels in the population.

A cross-sectional study of the individual, social, and built environmental correlates of pedometer based physical activity among elementary school children

Background: Children who participate in regular physical activity obtain health benefits. Preliminary pedometerbased cut-points representing sufficient levels of physical activity among youth have been established; however limited evidence regarding correlates of achieving these cut-points exists. The purpose of this study was to identify correlates of pedometer-based cut-points among elementary school-aged children.
Method: A cross-section of children in grades 5-7 (10-12 years of age) were randomly selected from the most (n = 13) and least (n = 12) ‘walkable’ public elementary schools (Perth, Western Australia), stratified by socioeconomic status. Children (n = 1480; response rate = 56.6%) and parents (n = 1332; response rate = 88.8%) completed a survey, and steps were collected from children using pedometers. Pedometer data were categorized to reflect the sex-specific pedometer-based cut-points of ≥15000 steps/day for boys and ≥12000 steps/day for girls. Associations between socio-demographic characteristics, sedentary and active leisure-time behavior, independent mobility, active transportation and built environmental variables - collected from the child and parent surveys - and meeting pedometer-based cut-points were estimated (odds ratios: OR) using generalized estimating equations.
Results: Overall 927 children participated in all components of the study and provided complete data. On average, children took 11407 ± 3136 steps/day (boys: 12270 ± 3350 vs. girls: 10681 ± 2745 steps/day; p < 0.001) and 25.9% (boys: 19.1 vs. girls: 31.6%; p < 0.001) achieved the pedometer-based cut-points. After adjusting for all other variables and school clustering, meeting the pedometer-based cut-points was negatively associated (p < 0.05) with being male (OR = 0.42), parent self-reported number of different destinations in the neighborhood (OR 0.93), and a friend’s (OR 0.62) or relative’s (OR 0.44, boys only) house being at least a 10-minute walk from home. Achieving the pedometer-based cut-points was positively associated with participating in screen-time < 2 hours/day (OR 1.88), not being driven to school (OR 1.48), attending a school located in a high SES neighborhood (OR 1.33), the average number of steps among children within the respondent’s grade (for each 500 step/day increase: OR 1.29), and living further than a 10-minute walk from a relative’s house (OR 1.69, girls only).
Conclusions: Comprehensive multi-level interventions that reduce screen-time, encourage active travel to/from school and foster a physically active classroom culture might encourage more physical activity among children.

Genetic changes, intra- and inter-specific introgression in farmed Nile tilapia (Oreochromis niloticus) in Thailand

Fourteen microsatellite loci were used to examine genetic changes of four strains in Nile tilapia (Oreochromis niloticus) derived from genetically improved farmed tilapia (GIFT) and two strains derived from a local Chitralada strain of Nile tilapia in Thailand. Reference populations, including the ninth generation of GIFT strain, the original Chitralada strain, two conspecific reference populations from Ivory Coast and Uganda, and one population each of Oreochromis mossambicus and Oreochromis aureus, were also examined. Despite minor genetic changes, three of the four GIFT-derived populations retained their purity as GIFT while genetic variation did not decline. One of the GIFT-derived populations showed high levels of introgression from the Chitralada strain. Likewise, introgression from GIFT to the Chitralada-derived populations was seen. Inter-specific introgression from O. mossambicus was observed in the GIFT reference population and one of the Chitralada-derived strains. Introgression from O. aureus was detected in one of the GIFT-derived populations with a history of intensive inter-strain crossing. However, the introgression resulted in elevated genetic variation relative to the Chitralada original strains.

An observational assessment of physical activity levels and social behaviour during elementary school recess

Objective: The purpose of the present study was to assess children’s physical activity, social play behaviour, activity type and social interactions during elementary school recess using a pre-validated systematic observation system.

Design: Cross-sectional.

Setting: Two elementary schools located in Merseyside, England.

Method: Fifty-six elementary school children (27 boys, 29 girls) were systematically observed during recess over a three-month period using a standardized physical activity observation instrument.

Results: The results revealed the boys were engaged in significantly higher levels of physical activity during recess than girls. The boys were also involved in more sport-specific activities and participated in larger group sizes. Positive associations between physical activity and availability of equipment during recess were also reported.

Conclusion: This study has confirmed recess as a valuable opportunity for elementary school children to increase their levels of physical activity. However, further studies with larger sample sizes need to identify and explore the relationship between physical activity (PA) and availability of equipment.