Zebrafish KLF4 is essential for anterior mesendoderm/pre-polster differentiation and hatching

Gene knockout studies of Kruppel-like factors (KLFs) in mice have shown essential roles in organogenesis. A screen for KLF family members in zebrafish identified many KLFs. One of these, zebrafish KLF4 (zKLF4) is the homologue of neptune, a Xenopus laevis KLF. zKLF4 is expressed from approximately 80% epiboly a patch of dorsal/anterior mesendodermal cells called the pre-polster and, subsequently, in the polster and hatching gland. Here we investigate the function of zKLF4 using morpholino-based antisense oligonucleotides. Knockdown of zKLF4 resulted in complete absence of hatching gland formation and subsequent hatching in zebrafish. In addition, there was early knockdown of expression of the pre-polster/anterior mesendoderm markers CatL, cap1, and BMP4. These results indicate zKLF4 is expressed within the pre-polster, an early mesendodermal site, and that it plays a critical role in the differentiation of these cells into hatching gland cells.

Loyalty without Conformity: Tailoring Self-perception as a Means of Balancing Belonging and Differentiation

We argue that members of individualist cultures balance their desire to belong with their desire to be different by maintaining a self-image as being loyal but relatively immune to group influence. Consistent with this, in Study 1 there was a strong tendency for people to rate themselves as being more independent (i.e., less conformist) than other people in their college. College students also rated themselves as being highly loyal to the group, however no self - other discrepancies were found on this dimension. This is despite the fact that traits of loyalty were rated more positively than were traits of independence. Study 2 provided evidence that culture influences the pattern of self - other discrepancies. Whereas people from individualist countries self-enhance on independence dimensions, people from collectivist countries self-enhance on loyalty dimensions. Again, these effects could not be explained as being a function of how positive these traits were seen to be, suggesting a cultural explanation rather than a straight forward superiority bias explanation for the observed discrepancies in self - other ratings. Results are discussed in relation to the SCENT model.

Differentiation between protective reflexes: Cardiac defense and startle

Rise time and duration are two parametric characteristics of the eliciting stimulus frequently used to differentiate among psychophysiological reflexes. The present research varied the duration (study 1) and rise time (study 2) of an intense acoustic stimulus to dissociate cardiac defense and cardiac startle using the eyeblink response as the external criterion of startle. In each study, 100 participants were presented with five white noise stimuli of 105 dB under one of five duration (50, 100, 250, 500, and 1000 ms) or rise time (0, 24, 48, 96, and 240 ms) conditions. Cardiac defense was affected by stimulus duration, present only in the 500- and 1000-ms conditions, but not by stimulus rise time, present in all rise time conditions. Rise time affected blink startle, but did not selectively alter the short latency accelerative component of the heart rate response, thus questioning whether it reflects startle.

Making decisions with the future in mind: Developmental and comparative identification of mental time travel

Mechanisms that produce behavior which increase future survival chances provide an adaptive advantage. The flexibility of human behavior is at least partly the result of one such mechanism, our ability to travel mentally in time and entertain potential future scenarios. We can study mental time travel in children using language. Current results suggest that key developments occur between the ages of three to five. However, linguistic performance can be misleading as language itself is developing. We therefore advocate the use of methodologies that focus on future-oriented action. Mental time travel required profound changes in humans' motivational system, so that current behavior could be directed to secure not just present, but individually anticipated future needs. Such behavior should be distinguishable from behavior based on current drives, or on other mechanisms. We propose an experimental paradigm that provides subjects with an opportunity to act now to satisfy a need not currently experienced. This approach may be used to assess mental time travel in nonhuman animals. We conclude by describing a preliminary study employing an adaptation of this paradigm for children. (c) 2005 Elsevier Inc. All rights reserved.

Examination of emotional priming among children and young adolescents: Developmental issues and its association with anxiety

An affective priming task was used to examine bias in the processing of threat-related material in 25 clinically anxious compared to 25 matched, non-anxious control children and young adolescents. No significant differences were found between anxious and non-anxious children in terms of priming effects. However, age-related differences were found depending upon the valence of the target, independent of anxiety status. Both younger (7-10 years) and older (11-14 years) children showed faster response times to pleasant targets when they were preceded by a congruent compared to incongruent stimulus, consistent with a traditional priming effect. For threat target stimuli, older children showed no difference in response latency according to the congruency of the prime-target valence. Younger children, in contrast, showed a reverse priming effect for threat target stimuli, with slower response times for threat-congruent trials than for threat targets preceded by a pleasant prime. Possible explanations for developmental differences in the processing of threat-related material are discussed.

Obsessive-compulsive disorder across developmental trajectory: Cognitive processing of threat in children, adolescents and adults

Background. While the cognitive theory of obsessive-compulsive disorder (OCD) is one of the most widely accepted accounts of the maintenance of the disorder in adults, no study to date has systematically evaluated the theory across children, adolescence and adults with OCD. Method. This paper investigated developmental differences in the cognitive processing of threat in a sample of children, adolescents and adults with OCD. Using an idiographic assessment approach, as well as self-report questionnaires, this study evaluated cognitive appraisals of responsibility, probability, severity, thought-action fusion (TAF), thought-suppression, self-doubt and cognitive control. It was hypothesised that there would be age related differences in reported responsibility for harm, probability of harm, severity of harm, thought suppression, TAR self-doubt and cognitive control. Results. Results of this study demonstrated that children with OCD reported experiencing fewer intrusive thoughts, which were less distressing and less uncontrollable than those experienced by adolescents and adults with OCD. Furthermore, responsibility attitudes, probability biases and thought suppression strategies were higher in adolescents and adults with OCD. Cognitive processes of TAF, perceived severity of harm, self-doubt and cognitive control were found to be comparable across age groups. Conclusions. These results suggest that the current cognitive theory of OCD needs to address developmental differences in the cognitive processing of threat. Furthermore, for a developmentally sensitive theory of OCD, further investigation is warranted into other possible age related maintenance factors. Implications of this investigation and directions for future research are discussed.

The matricellular protein SPARC is internalized in Sertoli, Leydig, and germ cells during testis differentiation

The gene encoding the matricellular protein secreted protein, acidic and rich in cysteine (SPARC) was identified in a screen for genes expressed sex-specifically during mouse gonad development, as being strongly upregulated in the male gonad from very early in testis development. We present here a detailed analysis of SPARC gene and protein expression during testis development, from 11.5 to 15.5 days post coitum (dpc). Section in situ hybridization analysis revealed that SPARC mRNA is expressed by the Sertoli cells in the testis cords and the fetal Leydig cells, found within the interstitial space between the testis cords. Immunodetection with anti-SPARC antibody showed that the protein was located inside the testis cords, within the cytoplasm of Sertoli and germ cells. In the interstitium, SPARC was present intracellularly within the Leydig cells. The internalization of SPARC in Sertoli, Leydig, and germ cells suggests that it plays an intracellular regulatory role in these cell types during fetal testis development.

Differentiation between and within groups: The influence of individualist and collectivist group norms

The power of individualist and collectivist group norms to influence intergroup and inter-individual differentiation was examined in three studies. Study I revealed that intergroup differentiation was lower when group norms prescribed individualism than when they prescribed collectivism. However inter-individual differentiation was higher when group norms endorsed individualism than when they promoted collectivism. In Studies 2 and 3 we found evidence for the moderating effect of group salience on the relationship between norms and differentiation. Specifically, the effect that individualist group norms reduced intergroup differentiation but enhanced inter-individual differentiation was more pronounced when group salience was high rather than low. This finding demonstrates that conformity to a group norm prescribing individualism influences the manner in which positive differentiation is expressed. The discussion focuses on the caveats of introducing individualist group norms when attempting to reduce intergroup differentiation. Copyright (c) 2006 John Wiley & Sons, Ltd.

Refining individualized consideration: Distinguishing developmental leadership and supportive leadership

This study explores the theoretical and empirical distinction between developmental leadership and supportive leadership, which are currently encompassed in a single sub dimension of transformational leadership, individualized consideration. Items were selected to assess these constructs, and hypotheses regarding the differential effects of developmental and supportive leadership were proposed. Confirmatory factor analyses provided support for the proposed distinction between developmental and supportive leadership, although these leadership factors were very strongly associated. Structural equation modelling and multi-level modelling results indicated that both developmental leadership and supportive leadership displayed unique relationships with theoretically selected outcome measures. Developmental leadership displayed significantly stronger relationships with job satisfaction, career certainty, affective commitment to the organization and role breadth self-efficacy than did supportive leadership. Results provide initial evidence in support of the discriminant validity of these two types of leadership. Discussion focuses on the need to further examine the construct of developmental leadership.

Neogenin: A multi-functional receptor regulating diverse developmental processes

Neogenin, a close relative of the axon guidance receptor Deleted in Colorectal Cancer (DCC), has been shown to be a receptor for members of the Netrin and Repulsive Guidance Molecule (RGM) families. While Netrin-l-Neogenin interactions result in a chernoattractive axon guidance response, the interaction between Neogenin and RGMa induces a chemorepulsive response. Evidence is now accumulating that Neogenin is a multi-functional receptor regulating many diverse developmental processes, including neural tube and mammary gland formation, myogenesis and angiogenesis. Little is known of the function of Neogenin in the adult, however, a novel role in the regulation of iron homeostasis is now emerging. While the signal transduction pathways activated by Neogenin are poorly understood, it is clear that the functional outcome of Neogenin activation, at least in the embryo, depends on both the developmental context as well as the nature of the ligand. (c) 2006 Elsevier Ltd. All rights reserved.

The impact of LMX differentiation on perceptions of team conflict and procedural justice climate

The fundamental tenet of Leader Member Exchange (LMX) theory is that leaders develop different quality relationships with each of their employees; however, to our knowledge, no study has investigated the impact of LMX differentiation on teams. Drawing upon the justice literature, we suggest that fostering different quality LMX relationships runs counter to principles of equality' and consistency, which are important for maintaining social harmony in groups, and perceptions of procedural fairness. We therefore propose that differential treatment of employees by the leader (as indicated by within-team variability in LMX relationships) will have a negative effect on team reladons, and percepdons of procedural jusdce climate. Two samples of employed individuals are used to invesdgate the hypothesized reladonships. Sample A consists of 74 individuals from a variety of occupadonal and organisadonal backgrounds, and Sample B consists of 152 individuals from an Australian organisadon dealing in the sale and service of heavy machiner)'. In both samples, high LMX variability within teams is associated with higher reports of team reladonal conflict, and lower reports of procedural jusdce climate. The results suggest that leaders may need to be caudous about fostering special relationships with only a select subset of employees.