Nightmares, life stress, and anxiety: An examination of tension reduction.

Do nightmares increase or decrease anxiety? Theoretical views of nightmares suggest that nightmares play out stressful events, decathecting their energy. A more pragmatic view suggests that nightmares that result in waking distress add to the burden of anxiety. The current study investigates whether negative life events are associated with an increase or decrease in anxiety attributable to nightmares in 624 adolescents aged between 12 and 19. The results indicate no support for a tension reduction hypothesis. There seems no relief from anxiety if a person reports nightmares, and the stronger the distress of waking (from nightmares), the more likely a person is to report anxiety, controlling for life events and the distress associated with life events. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The stress and strain of cytokinesis

The ultimate goal of all signaling pathways in cytokinesis is to control the mechanical separation of the mother cell into two daughter cells. Because of the intrinsic mechanical nature of cytokinesis, it is essential to understand fully how cell shapes and the material properties of the cell are generated, how these shapes and material properties create force, and how motor proteins such as myosin-II modify the system to achieve successful cytokinesis. In this review (which is part of the Cytokinesis series), we discuss the relevant physical properties of cells, how these properties are measured and the basic models that are used to understand cell mechanics. Finally, we present our current understanding of how cytokinesis mechanics work.     

Separation anxiety at the centromere

During mitosis, replicated sister-chromatids must maintain cohesion as they attach to the mitotic spindle. At anaphase, cohesion is lost simultaneously along the entire chromosome, releasing sisters from one another and allowing them to segregate to opposite poles. During meiosis, sisters separate in a two-step process. At anaphase of meiosis I, cohesion is lost along the chromosome arms but is maintained at centromeric regions. Not until meiosis II are sister chromatids able to break the connection at the centromere and separate away from one another. Recent studies suggest that the centromere exhibits dynamics that are very different compared with those of the chromatid arms during both mitosis and meiosis. This review discusses the nature of the specialized chromatid cohesion seen at the centromere.     

Social buffering: relief from stress and anxiety

Communication is essential to members of a society not only for the expression of personal information, but also for the protection from environmental threats. Highly social mammals have a distinct characteristic: when conspecific animals are together, they show a better recovery from experiences of distress. This phenomenon, termed 'social buffering', has been found in rodents, birds, non-human primates and also in humans. This paper reviews classical findings on social buffering and focuses, in particular, on social buffering effects in relation to neuroendocrine stress responses. The social cues that transmit social buffering signals, the neural mechanisms of social buffering and a partner's efficacy with respect to social buffering are also detailed. Social contact appears to have a very positive influence on the psychological and the physiological aspects of social animals, including human beings. Research leading towards further understanding of the mechanisms of social buffering could provide alternative medical treatments based on the natural, individual characteristics of social animals, which could improve the quality of life.     

Distinct roles of profilin in cell morphological changes: microspikes, membrane ruffles, stress fibers, and cytokinesis.

Here we report the functional importance of profilin in various actin-mediated morphological changes using H119E mutant profilin I, which is deficient only in actin binding. In the case of actin-protrusive structures from the plasma membrane, H119E-profilin was shown to suppress the formation of Cdc42-induced actin microspikes and Rac-induced membrane ruffles. Conversely, Rho-induced stress fiber formation seemed to occur independently of H119E-profilin introduction. Furthermore, H119E-profilin blocked cleavage furrow ingression and subsequent adhesion to the substratum during cell division, a process in which actin plays indispensable roles.     

Microtubules, membranes and cytokinesis

Proper division of the cell requires coordination between chromosome segregation by the mitotic spindle and cleavage of the cell by the cytokinetic apparatus. Interactions between the mitotic spindle, the contractile ring and the plasma membrane ensure that the cleavage furrow is properly placed between the segregating chromosomes and that new membrane compartments are formed to produce two daughter cells. The microtubule midzone is able to stimulate the cortex of the cell to ensure proper ingression and completion of the cleavage furrow. Specialized microtubule structures are responsible for directing membrane vesicles to the site of cell cleavage, and vesicle fusion is required for the proper completion of cytokinesis.     

Serotonergic innervation of the amygdala: targets, receptors, and implications for stress and anxiety

The amygdala is a core component of neural circuits that mediate processing of emotional, particularly anxiety and fear-related stimuli across species. In addition, the nuclear complex plays a key role in the central nervous system stress response, and alterations in amygdala responsivity are found in neuropsychiatric disorders, especially those precipitated or sustained by stressors. Serotonin has been shown to shape and fine-tune neural plasticity in development and adulthood, thereby allowing for network flexibility and adaptive capacity in response to environmental challenges, and is implicated in the modulation of stimulus processing and stress sensitivity in the amygdala. The fact that altered amygdala activity patterns are observed upon pharmacological manipulations of serotonergic transmission, as well as in carriers of genetic variations in serotonin pathway-associated signaling molecules representing risk factors for neuropsychiatric disorders, underlines the importance of understanding the role and mode of action of serotonergic transmission in the amygdala for human psychopathology. Here, we present a short overview over organizational principles of the amygdala in rodents, non-human primates and humans, and review findings on the origin, morphology, and targets of serotonergic innervation, the distribution patterns and cellular expression of serotonin receptors, and the consequences of stress and pharmacological manipulations of serotonergic transmission in the amygdala, focusing particularly on the extensively studied basolateral complex and central nucleus.     

Cell division: SIN, cytokinesis and ethanol dependency

A novel mutant screen in fission yeast has identified the 'ethanol dependent' protein etd1p as a potential link between the septation initiation network (SIN), which initiates cytokinesis, and the actomyosin contractile ring that drives separation of the two daughter cells at the end of mitosis.     

Testosterone levels and stress in women: the role of stress coping strategies, anxiety and sex role identification

This study evaluated the relation between testosterone changes in response to anticipatory stress and several psychological variables that contribute to the stress reaction. Salivary testosterone was determined in 76 female students under stress-free conditions and before an important examination. Individual stress reactions were highly variable in direction and extent: both significant increases and decreases were found. Thus the data did not confirm previous findings of general increases in testosterone levels under stress in women. Depending on the women's level of trait anxiety (assessed via STAI) and the general use of positive or negative cognitive coping strategies (assessed via SVF), we found significant differences in their baseline testosterone levels. Individual endocrine changes under stress were correlated with baseline testosterone levels: High testosterone concentrations at rest were more likely to drop under anticipatory stress than low concentrations. These contrasting effects can be explained by the significant interaction of trait anxiety and the sex role dimension of masculinity (assessed via BSRI) with testosterone production in females.     

Stuck in the middle: Rac, adhesion, and cytokinesis

Rho family small GTPases (Rac, RhoA, and Cdc42) function at the core of cytokinesis, the physical division of one cell into two. In this issue, Bastos et al. (2012. J. Cell Biol. http://dx.doi.org/10.1083/jcb.201204107) identify a new role for Rac inhibition: to release cell adhesion at the division plane and allow efficient constriction of the contractile ring. They show that the GTPase-activating protein, CYK4, suppresses equatorial cell substrate adhesion by inhibiting Rac and therefore its effectors ARFGEF7 and PAK1/2.     

Psychosocial stress, symptoms, and anxiety of male and female teachers in Greece

Psychosocial stress as measured by a Greek adaptation of the Schedule of Recent Experiences (SRE) constructed by Holmes and Rahe was studied in relation to symptoms, manifest anxiety, visits to doctor, and health concerns using 129 male and female Greek elementary school teachers. Psychosocial stress was related to number of symptoms and to level of manifest anxiety only with women. Although no sex differences were found in average psychosocial ratings, males and females reported different stressful life events. Females reported more symptoms than males, and had higher manifest anxiety. Relationships of sex differences to cultural norms are discussed.     

NoCut: cytokinesis in check

In this issue of Cell, Norden et al. (2006) describe a new pathway, NoCut, that links the completion of chromosome segregation to the onset of cytokinesis in budding yeast. In NoCut, Aurora kinase (Ipl1) at the spindle midzone negatively regulates cytokinesis through two proteins previously identified to be involved in cell polarity, Boi1 and Boi2.     

Dynamin and cytokinesis

Animal and plant cytokineses appear morphologically distinct. Recent studies, however, have revealed that these cellular processes have many things in common, including the requirement of co-ordinated membrane trafficking and cytoskeletal dynamics. At the intersection of these two processes are the members of the dynamin family of ubiquitous eukaryotic GTPases. In this review, we highlight the conserved contribution of classical dynamin and dynamin-related proteins during cytokinesis in both animal and plant systems.     

Mitosis and cytokinesis in subconfluent endothelial cells exposed to increasing levels of shear stress

An in vitro flow apparatus in combination with cultured endothelium was used to determine the effects of fluid-generated shear stress on cells undergoing mitosis and cytokinesis. Cell responses were recorded by time-lapse video microscopy under phase contrast or Hoffman modulation contrast optics. Completion of cell division in mitotic cells was dependent upon both the initial presence of intercellular attachments and the magnitude of fluid wall shear stress. In nonisolated populations, 95.3%, 69.5%, and 57.1% of the cells completed cell division as opposed to 66.6%, 20.4%, and 11.9% in the isolated cell groups at 2.8, 14.1, and 33 dynes/cm², respectively. Prestressing cells for 14 h prior to monitoring failed to increase retention of isolated mitotic cells. The presence of neighboring cells facilitated replication by providing an anchoring attachment or a luminal surface for completion of division. Cell detachment most commonly occurred at the onset of cytokinesis when substrate contact areas were minimal and focal contacts were absent. A comparison between no flow controls and shear stress specimens indicated no significant differences in transit times for mitosis and cytokinesis. Thus, subconfluent endothelial cells may be more susceptible to detachment during cell division due to increases in shear stress, the absence of intercellular attachments, and reduced cell-substrate contacts. © 1994 wiley-Liss, Inc.