Pre-adjustment of adult attachment style to extrinsic risk levels via early attachment style is neither specific, nor reliable, nor effective, and is thus not an adaptation

The mechanism proposed by Del Giudice by which adult attachment style is adapted to the extrinsic risk in the local environment via attachment style during the early years does not fulfill important criteria of an adaptation. The proposed mechanism is neither specific, nor developmentally reliable, nor effective. Therefore, it should not be considered an adaptation

Commentary

Wetensch. publicati

Polarized sphingolipid transport from the subapical compartment:Evidence for distinct sphingolipid domains

In polarized HepG2 cells, the sphingolipids glucosylceramide and sphingomyelin (SM), transported along the reverse transcytotic pathway, are sorted in subapical compartments (SACs), and subsequently targeted to either apical or basolateral plasma membrane domains, respectively. In the present study, evidence is provided that demonstrates that these sphingolipids constitute separate membrane domains at the luminal side of the SAC membrane. Furthermore, as revealed by the use of various modulators of membrane trafficking, such as calmodulin antagonists and dibutyryl-cAMP, it is shown that the fate of these separate sphingolipid domains is regulated by different signals, including those that govern cell polarity development. Thus under conditions that stimulate apical plasma membrane biogenesis, SM is rerouted from a SAC-to-basolateral to a SAC-to-apical pathway. The latter pathway represents the final leg in the transcytotic pathway, followed by the transcytotic pIgR–dIgA protein complex. Interestingly, this pathway is clearly different from the apical recycling pathway followed by glucosylceramide, further indicating that randomization of these pathways, which are both bound for the apical membrane, does not occur. The consequence of the potential coexistence of separate sphingolipid domains within the same compartment in terms of “raft” formation and apical targeting is discussed

Recycling endosomes

The endocytic and exocytic system is important for cells to communicate with their surroundings. For instance, endocytosis allows the regulated internalisation of receptors (which can be ligand bound or not) into peripheral early endosomes and can thus modulate responses to external stimuli. Internalised molecules can be degraded after entering the late-endosomal/lysosomal pathway or be recycled to the cell surface (Maxfield and McGraw, 2004). Recycling to the cell surface can occur directly from peripheral early endosomes. However, many cells display a distinct subpopulation of endosomes that have a slightly higher pH of ~6.4 and also recycle membrane components. These are typically located deeper in the cell and centered around the microtubule-organising centre (MTOC) (Perret et al., 2005). These so-called recycling endosomes (REs) display a heterogeneous tubular-vesicular morphology, which suggests dynamic and intense trafficking activity, and connect the endocytic pathway to the exocytic pathway (Ang et al., 2004; Lock and Stow, 2005; Murray et al., 2005). The most prominent RE marker to date is the small GTPase Rab11. Studies of the function of Rab11 and the proteins with which it interacts in various experimental systems and organisms suggest that cells use REs for the delivery of membranes to regions of their surface that are subject to dynamic reorganisation, probably through regulated interactions with the exocyst, a multiprotein complex containing the Sec5, Sec6, Sec8, Sec10, Sec15 and Exo70 proteins that is thought to recruit material to areas of membrane growth. Consequently, REs are implicated in the regulation of a variety of cellular processes that depend on such trafficking. Several of these are highlighted in the poster and discussed briefly below. Epithelial cell-cell adhesion E-cadherin-mediated cell-cell adhesion controls epithelial cell polarisation, 1679Cell Science at a Glance (See poster insert

The relationship between quality of attachment in infancy and IQ in Kindergarten

Wetensch. publicatieFaculteit der Sociale Wetenschappe

A rotating molecular ruler : determining nanometer-scale particle-particle distances in an optomagnetic cluster assay

We investigate a fast and sensitive optomagnetic biomarker detection technology based on magnetic particles. Antibody-coated superparamagnetic particles capture biomarker molecules and form clusters with a biomarker molecule sandwiched between two particles. The particle clusters are actuated using a rotating magnetic field, which induces an oscillating light scattering cross-section (see Fig. 1a). Sub-picomolar biomarker concentrations can be resolved by the light scattering signals [Ranzoni et al, Nanoletters 2011; ACS Nano 2012]. In this paper we report a method to quantify inter-particle distances with nanometer resolution. The light scattering data show high-frequency signal components (see Fig. 1b). Simulations show that high-frequency components hold detailed information about the geometry of the particle clusters, including a strong dependence on the inter-particle distance (see Fig. 1c). We will report the simulation results and experimental data of corresponding model cluster assays