Protein trafficking in the mitochondrial intermembrane space: mechanisms and links to human disease

Mitochondria fulfill a diverse range of functions in cells including oxygen metabolism, homeostasis of inorganic ions and execution of apoptosis. Biogenesis of mitochondria relies on protein import pathways that are ensured by dedicated multiprotein translocase complexes localized in all sub-compartments of these organelles. The key components and pathways involved in protein targeting and assembly have been characterized in great detail over the last three decades. This includes the oxidative folding machinery in the intermembrane space, which contributes to the redox-dependent control of proteostasis. Here, we focus on several components of this system and discuss recent evidence suggesting links to human proteopathy

Oxidative protein biogenesis and redox regulation in the mitochondrial intermembrane space

Mitochondria are organelles that play a central role in cellular metabolism, as they are responsible for processes such as iron/sulfur cluster biogenesis, respiration and apoptosis. Here, we describe briefly the various protein import pathways for sorting of mitochondrial proteins into the different subcompartments, with an emphasis on the targeting to the intermembrane space. The discovery of a dedicated redox-controlled pathway in the intermembrane space that links protein import to oxidative protein folding raises important questions on the redox regulation of this process. We discuss the salient features of redox regulation in the intermembrane space and how such mechanisms may be linked to the more general redox homeostasis balance that is crucial not only for normal cell physiology but also for cellular dysfunction

Split-DHFR as a protein complementation assay for localisation and interactions of yeast mitochondrial proteins

Protein complementation assays (PCAs) utilising two fragments of a reporter protein – fused to two potentially interacting proteins of interest – are a common method of analysing protein-protein interactions (PPIs). This approach, using split dihydrofolate reductase (DHFR) as a reporter protein, has been previously carried out for cytosolic Saccharomyces cerevisiae proteins. The focus of this study was to establish a split-DHFR assay specifically for use in analysing yeast mitochondrial PPIs in the intermembrane space (IMS), which has not been done before. A strategy to overcome the problem endogenous DHFR activity had to be developed using a modified strain of S. cerevisiae for the specific application here. Further, plasmids containing two positive control proteins, Tim9 and Tim10 (two well-known interacting proteins of the IMS) were cloned for transformation into yeast strain BY4741. Several other plasmids bearing various control proteins were designed and some of them cloned, although we required more time to have the full set of tools to establish the assay

2008 Statistics

2008 Men\u27s Track and Field Statistics, George Fox College

Demographic Estimates from Y Chromosome Microsatellite Polymorphisms: Analysis of a Worldwide Sample

Polymorphisms in microsatellites on the human Y chromosome have been used to estimate important demographic parameters of human history. We compare two coalescent-based statistical methods that give estimates for a number of demographic parameters using the seven Y chromosome polymorphisms in the HGDP-CEPH Cell Line Panel, a collection of samples from 52 worldwide populations. The estimates for the time to the most recent common ancestor vary according to the method used and the assumptions about the prior distributions of model parameters, but are generally consistent with other global Y chromosome studies. We explore the sensitivity of these results to assumptions about the prior distributions and the evolutionary models themselves

Researching belonging with people with learning disabilities:Self-building active community lives in the context of personalisation

We wanted to understand more about how people with learning disabilities are building active community lives to help belonging. We spoke to 39 people from 29 different support organisations, 7 local authority representatives and 43 people with learning disabilities. They said belonging was about having the time to connect with other people in “everyday” places, being part of a supportive network and having the right choice and information. Belonging is like a cake. It needs the right ingredients. These ingredients include the right combination of people, places and times. Because of cuts to funding, many people with learning disabilities lack the right support, choice and information to access their communities. This is not belonging. ​. Abstract: Background This journal article draws on findings from a research project that examined how people with learning disabilities and their allies were seeking to build a sense of belonging. We wanted to focus on the concept of “belonging” in the context of personalisation and reduced government social care funding. Specifically, we sought to understand how people with learning disabilities and their supporters were coming together to “self-build” networks of support including friendship clubs and self-advocacy groups to enable a greater sense of belonging in their local communities. Methods Qualitative interviews were conducted with seven local authority representatives across four case study areas in the UK, as well as 39 staff across 29 organisations providing a range of day and evening support and activities. We also talked to 43 people with learning disabilities across the four areas about their experiences. Findings Our findings demonstrate how belonging involves a complex configuration of actors, places, times, relationships and institutional roles (much like the ingredients in a cake). The ways in which belonging intersects with agency and choice was also identified as an important and novel finding of our study. Conclusion While belonging is often presented to people as a desirable and realisable outcome of social inclusion policies, cuts in funding and a lack of appropriate support frustrate people's desires to meaningfully belong with other people in their local community. This demonstrates the importance of supporting social environments that meet people's needs for social connectedness and belonging

Demographic estimates from Y chromosome microsatellite polymorphisms: Analysis of a worldwide sample

Polymorphisms in microsatellites on the human Y chromosome have been used to estimate important demographic parameters of human history. We compare two coalescent-based statistical methods that give estimates for a number of demographic parameters using the seven Y chromosome polymorphisms in the HGDP-CEPH Cell Line Panel, a collection of samples from 52 worldwide populations. The estimates for the time to the most recent common ancestor vary according to the method used and the assumptions about the prior distributions of model parameters, but are generally consistent with other global Y chromosome studies. We explore the sensitivity of these results to assumptions about the prior distributions and the evolutionary models themselves

The Doors and People Test:The effect of frontal lobe lesions on recall and recognition memory performance

Objective: Memory deficits in patients with frontal lobe lesions are most apparent on free recall tasks that require the selection, initiation, and implementation of retrieval strategies. The effect of frontal lesions on recognition memory performance is less clear with some studies reporting recognition memory impairments but others not. The majority of these studies do not directly compare recall and recognition within the same group of frontal patients, assessing only recall or recognition memory performance. Other studies that do compare recall and recognition in the same frontal group do not consider recall or recognition tests that are comparable for difficulty. Recognition memory impairments may not be reported because recognition memory tasks are less demanding. Method: This study aimed to investigate recall and recognition impairments in the same group of 47 frontal patients and 78 healthy controls. The Doors and People Test was administered as a neuropsychological test of memory as it assesses both verbal and visual recall and recognition using subtests that are matched for difficulty. Results: Significant verbal and visual recall and recognition impairments were found in the frontal patients. Conclusion: These results demonstrate that when frontal patients are assessed on recall and recognition memory tests of comparable difficulty, memory impairments are found on both types of episodic memory test

Structure–activity relationship study of selective benzimidazole-based inhibitors of Cryptosporidium parvum IMPDH

Cryptosporidium parasites are important waterborne pathogens of both humans and animals. The Cryptosporidium parvum and Cryptosporidium hominis genomes indicate that the only route to guanine nucleotides is via inosine 5?-monophosphate dehydrogenase (IMPDH). Thus the inhibition of the parasite IMPDH presents a potential strategy for treating Cryptosporidium infections. A selective benzimidazole-based inhibitor of C. parvum IMPDH (CpIMPDH) was previously identified in a high throughput screen. Here we report a structure–activity relationship study of benzimidazole-based compounds that resulted in potent and selective inhibitors of CpIMPDH. Several compounds display potent antiparasitic activity in vitro

Cognitive reserve proxies do not differentially account for cognitive performance in patients with focal frontal and non-frontal lesions

Objective: Cognitive reserve (CR) suggests that premorbid efficacy, aptitude, and flexibility of cognitive processing can aid the brain\u2019s ability to cope with change or damage. Our previous work has shown that age and literacy attainment predict the cognitive performance of frontal patients on frontal-executive tests. However, it remains unknown whether CR also predicts the cognitive performance of non-frontal patients. Method: We investigated the independent effect of a CR proxy, National Adult Reading Test (NART) IQ, as well as age and lesion group (frontal vs. non-frontal) on measures of executive function, intelligence, processing speed, and naming in 166 patients with focal, unilateral frontal lesions; 91 patients with focal, unilateral non-frontal lesions; and 136 healthy controls. Results: Fitting multiple linear regression models for each cognitive measure revealed that NART IQ predicted executive, intelligence, and naming performance. Age also significantly predicted performance on the executive and processing speed tests. Finally, belonging to the frontal group predicted executive and naming performance, while membership of the non-frontal group predicted intelligence. Conclusions: These findings suggest that age, lesion group, and literacy attainment play independent roles in predicting cognitive performance following stroke or brain tumour. However, the relationship between CR and focal brain damage does not differ in the context of frontal and non-frontal lesions