Mitochondrial precursor proteins are imported through a hydrophilic membrane environment

We have analyzed how translocation intermediates of imported mitochondrial precursor proteins, which span contact sites, interact with the mitochondrial membranes. F1-ATPase subunit β(F1β) was trapped at contact sites by importing it into Neurospora mitochondria in the presence of low levels of nucleoside triphosphates. This F1β translocation intermediate could be extracted from the membranes by treatment with protein denaturants such as alkaline pH or urea. By performing import at low temperatures, the ADP/ATP carrier was accumulated in contact sites of Neurospora mitochondria and cytochrome b2 in contact sites of yeast mitochondria. These translocation intermediates were also extractable from the membranes at alkaline pH. Thus, translocation of precursor proteins across mitochondrial membranes seems to occur through an environment which is accessible to aqueous perturbants. We propose that proteinaceous structures are essential components of a translocation apparatus present in contact sites

The accountability of advocacy NGOs: insights from the online community of practice

Advocacy non-governmental organisations (NGOs) play an important role in society by keeping in check the power of corporations and governments and uncovering rights violations. They differ from other NGOs in terms of their agenda, funding structure and the stakeholders they serve, and operate in a context characterised by increasing demands for transparency, accountability and responsible advocacy. This study examines how the accountability agenda of advocacy NGOs is shaped by the need to maintain independence, preserve values and keep reputation unsullied when faced with financial and legitimacy pressures. A netnography method is employed to analyse the discussions taking place in the NGOs’ online community of practice to understand the implications of the accountability challenges faced by advocacy NGOs through the perceptions of NGO professionals. The study reveals that the accountability agenda of advocacy NGOs is determined by the interrelated threats of financial vulnerability, potential loss of independence, legitimacy challenges and the high level of public scrutiny. The findings highlight that imperfect accountability mechanisms (e.g. financial reporting and performance management systems) hinder the ability of advocacy NGOs to demonstrate their accountability

An Integrated Micro- and Macroarchitectural Analysis of the Drosophila Brain by Computer-Assisted Serial Section Electron Microscopy

A new software package allows for dense electron microscopy reconstructions of neuronal networks in the fruit fly brain, and reveals specific differences in microcircuits between insects and vertebrates

Combined Inactivation of pRB and Hippo Pathways Induces Dedifferentiation in the Drosophila Retina

Functional inactivation of the Retinoblastoma (pRB) pathway is an early and obligatory event in tumorigenesis. The importance of pRB is usually explained by its ability to promote cell cycle exit. Here, we demonstrate that, independently of cell cycle exit control, in cooperation with the Hippo tumor suppressor pathway, pRB functions to maintain the terminally differentiated state. We show that mutations in the Hippo signaling pathway, wts or hpo, trigger widespread dedifferentiation of rbf mutant cells in the Drosophila eye. Initially, rbf wts or rbf hpo double mutant cells are morphologically indistinguishable from their wild-type counterparts as they properly differentiate into photoreceptors, form axonal projections, and express late neuronal markers. However, the double mutant cells cannot maintain their neuronal identity, dedifferentiate, and thus become uncommitted eye specific cells. Surprisingly, this dedifferentiation is fully independent of cell cycle exit defects and occurs even when inappropriate proliferation is fully blocked by a de2f1 mutation. Thus, our results reveal the novel involvement of the pRB pathway during the maintenance of a differentiated state and suggest that terminally differentiated Rb mutant cells are intrinsically prone to dedifferentiation, can be converted to progenitor cells, and thus contribute to cancer advancement

NrCAM, a neuronal system cell-adhesion molecule, is induced in papillary thyroid carcinomas

NrCAM (neuron-glia-related cell-adhesion molecule) is primarily, although not solely, expressed in the nervous system. In the present study, NrCAM expression was analysed in a series (46) of papillary thyroid carcinomas (PTCs) and paired normal tissues (NT). Quantitative reverse transcriptase (QRT)-PCR revealed that NrCAM expression was upregulated in all PTCs compared to normal thyroid, whatever the stage or size of the primary tumour. NrCAM transcript levels were 1.3- to 30.7-fold higher in PTCs than in NT. Immunohistochemistry (IHC) confirmed that the expression of NrCAM was considerably higher in tumours (score 2+/3+) than in adjacent normal paratumoural thyroid tissue. The NrCAM protein was detected in all but three (93.3%) PTC samples, and it was mainly cytoplasmic; in some cases there was additional membranous localisation – basolateral and partly apical. In the normal thyroid and tissues surrounding tumours, focal NrCAM immunolabelling was seen only in follicles containing tall cells, where staining was restricted to the apical pole of thyrocytes. Western blot analysis corroborated the QRT–PCR and IHC results, showing higher NrCAM protein levels in PTCs than in paired NT. The level of overexpression of the NrCAM mRNA in tumourous tissue appeared to be independent of the primary tumour stage (pT) or the size of the PTC. These data provide the first evidence that NrCAM is overexpressed in human PTCs at the mRNA and protein levels, whatever the tumour stage. Thus, the induction and upregulation of NrCAM expression could be implicated in the pathogenesis and behaviour of papillary thyroid cancers

A Fluorescent Glycolipid-Binding Peptide Probe Traces Cholesterol Dependent Microdomain-Derived Trafficking Pathways

10.1371/journal.pone.0002933PLoS ONE38

Enriched Environment Experience Overcomes Learning Deficits and Depressive-Like Behavior Induced by Juvenile Stress

Mood disorders affect the lives and functioning of millions each year. Epidemiological studies indicate that childhood trauma is predominantly associated with higher rates of both mood and anxiety disorders. Exposure of rats to stress during juvenility (JS) (27–29 days of age) has comparable effects and was suggested as a model of induced predisposition for these disorders. The importance of the environment in the regulation of brain, behavior and physiology has long been recognized in biological, social and medical sciences. Here, we studied the effects of JS on emotional and cognitive aspects of depressive-like behavior in adulthood, on Hypothalamic-Pituitary-Adrenal (HPA) axis reactivity and on the expression of cell adhesion molecule L1 (L1-CAM). Furthermore, we combined it with the examination of potential reversibility by enriched environment (EE) of JS – induced disturbances of emotional and cognitive aspects of behavior in adulthood. Three groups were tested: Juvenile Stress –subjected to Juvenile stress; Enriched Environment – subjected to Juvenile stress and then, from day 30 on to EE; and Naïves. In adulthood, coping and stress responses were examined using the elevated plus-maze, open field, novel setting exploration and two way shuttle avoidance learning. We found that, JS rats showed anxiety- and depressive-like behaviors in adulthood, altered HPA axis activity and altered L1-CAM expression. Increased expression of L1-CAM was evident among JS rats in the basolateral amygdala (BLA) and Thalamus (TL). Furthermore, we found that EE could reverse most of the effects of Juvenile stress, both at the behavioral, endocrine and at the biochemical levels. The interaction between JS and EE resulted in an increased expression of L1-CAM in dorsal cornu ammonis (CA) area 1 (dCA1)