Tropomyosin Promotes Lamellipodial Persistence by Collaborating with Arp2/3 at the Leading Edge

At the leading edge of migrating cells, protrusion of the lamellipodium is driven by Arp2/3-mediated polymerization of actin filaments [1]. This dense, branched actin network is promoted and stabilized by cortactin [2, 3]. In order to drive filament turnover, Arp2/3 networks are remodeled by proteins such as GMF, which blocks the actin-Arp2/3 interaction [4, 5], and coronin 1B, which acts by directing SSH1L to the lamellipodium where it activates the actin-severing protein cofilin [6, 7]. It has been shown in vitro that cofilin-mediated severing of Arp2/3 actin networks results in the generation of new pointed ends to which the actin-stabilizing protein tropomyosin (Tpm) can bind [8]. The presence of Tpm in lamellipodia, however, is disputed in the literature [9-19]. Here, we report that the Tpm isoforms 1.8/9 are enriched in the lamellipodium of fibroblasts as detected with a novel isoform-specific monoclonal antibody. RNAi-mediated silencing of Tpm1.8/9 led to an increase of Arp2/3 accumulation at the cell periphery and a decrease in the persistence of lamellipodia and cell motility, a phenotype consistent with cortactin- and coronin 1B-deficient cells [2, 7]. In the absence of coronin 1B or cofilin, Tpm1.8/9 protein levels are reduced while, conversely, inhibition of Arp2/3 with CK666 leads to an increase in Tpm1.8/9 protein. These findings establish a novel regulatory mechanism within the lamellipodium whereby Tpm collaborates with Arp2/3 to promote lamellipodial-based cell migration

Change or control? Developing dialogues between research and public protection

This paper aims to scope out some of the implications of desistance research for the community management of high risk offenders. Acknowledging the limited empirical research exploring this interface, this paper outlines the evolving evidence base and what this tells us about the process of desistance and what supports it. The evidence as to whether 'high risk offenders' desist and what we know about this process is discussed prior to outlining the landscape of current and principal practice approaches which can be located in the community/public protection model. Potential dialogues between desistance research and public protection practices are discussed to explore ensuing implications and opportunities for practice

Characterisation of pathogen-specific regions and novel effector candidates in Fusarium oxysporum f. sp. cepae

A reference-quality assembly of Fusarium oxysporum f. sp. cepae (Foc), the causative agent of onion basal rot has been generated along with genomes of additional pathogenic and non-pathogenic isolates of onion. Phylogenetic analysis confirmed a single origin of the Foc pathogenic lineage. Genome alignments with other F. oxysporum ff. spp. and non pathogens revealed high levels of syntenic conservation of core chromosomes but little synteny between lineage specific (LS) chromosomes. Four LS contigs in Foc totaling 3.9 Mb were designated as pathogen-specific (PS). A two-fold increase in segmental duplication events was observed between LS regions of the genome compared to within core regions or from LS regions to the core. RNA-seq expression studies identified candidate effectors expressed in planta, consisting of both known effector homologs and novel candidates. FTF1 and a subset of other transcription factors implicated in regulation of effector expression were found to be expressed in planta

The Nuclear Protein Sge1 of Fusarium oxysporum Is Required for Parasitic Growth

Dimorphism or morphogenic conversion is exploited by several pathogenic fungi and is required for tissue invasion and/or survival in the host. We have identified a homolog of a master regulator of this morphological switch in the plant pathogenic fungus Fusarium oxysporum f. sp. lycopersici. This non-dimorphic fungus causes vascular wilt disease in tomato by penetrating the plant roots and colonizing the vascular tissue. Gene knock-out and complementation studies established that the gene for this putative regulator, SGE1 (SIX Gene Expression 1), is essential for pathogenicity. In addition, microscopic analysis using fluorescent proteins revealed that Sge1 is localized in the nucleus, is not required for root colonization and penetration, but is required for parasitic growth. Furthermore, Sge1 is required for expression of genes encoding effectors that are secreted during infection. We propose that Sge1 is required in F. oxysporum and other non-dimorphic (plant) pathogenic fungi for parasitic growth

EphB2 acts via ERK signalling to promote active cell repulsion and cell sorting

Effective cell segregation is essential for the establishment and maintenance of tissue organisation during embryogenesis, yet our understanding of the cellular and molecular mechanisms that allow cells to segregate is lacking. Using a new in vitro model of cell sorting, we show that HT1080 fibrosarcoma cells, unlike NIH3T3 fibroblasts, will actively sort and segregate from epithelial populations in culture. The differential sorting capacity of these populations is related to their distinct dynamics of contact inhibition of locomotion (CIL) during heterotypic cell collisions; while both NIH3T3 fibroblasts and HT1080 fibrosarcoma cells will cease their forward motion upon collision with an epithelial cell, only the fibrosarcoma cells are actively repelled, which leads to emergent segregation of the populations. Eph-ephrin signalling has been widely shown to play a role in CIL in numerous cell types. Indeed, knocking down the Ephrin receptor EphB2 in fibrosarcoma cells leads to specific disruption of the repulsion phase of the CIL response and failure of cell sorting. We further demonstrate a role for MAPK signalling in the fibrosarcoma CIL response as ERK phosphorylation is specifically increased in fibrosarcoma cells undergoing sorting with epithelial cells. Furthermore, inhibiting MAPK signalling also leads to aberrant fibrosarcoma cell repulsion and failure of segregation from epithelial cells. This data suggests that cell sorting is an active process requiring repulsive interactions during cell segregation which, in fibrosarcoma cells, requires both Ephrin and MAPK signalling

A pilot study of the delivery of occupational therapy in long term care settings under the medicare prospective payment system.

OBJECTIVE: The purpose of this pilot study was to examine occupational therapists\u27 perceptions of practice in skilled nursing facilities since the implementation of the Medicare Prospective Payment System (PPS). METHOD: A survey was sent to 250 randomly selected occupational therapists who had worked or were currently working in skilled nursing facilities for a minimum of two years. RESULTS: A majority of therapists reported an increase in caseload size since the implementation of the new prospective payment system. Most also noted increasing expectations to maintain patients on their caseloads for longer periods of time. Many reported that their facilities were decreasing the number of level II fieldwork students they were accepting. An even greater number reported that their facilities were decreasing the amounts of their continuing education budgets. A significant number also reported that they felt the quality of life for their residents had decreased since the implementation of prospective payment. CONCLUSION: This pilot survey may indicate some problematic trends in occupational therapists\u27 perceptions of practice in skilled nursing facilities. There may be a relationship between these trends and the implementation of prospective payment in these settings. Further studies are recommended to more deeply assess occupational therapists\u27 practice perceptions, as well as the quality of life of patients in skilled nursing facilities. Research is also needed to determine if occupational therapists\u27 perceptions of practice in skilled nursing facilities changes or stabilizes under the prospective payment system

Antibiotic-loaded synthetic calcium sulfate beads for prevention of bacterial colonization and biofilm formation in periprosthetic infections

Periprosthetic infection (PI) causes significant morbidity and mortality in fixation and joint arthroplasty and has been extensively linked to the formation of bacterial biofilms. Poly(methyl methacrylate) (PMMA) cement or beads are commonly used for antibiotic release to the site of infection but display variable elution kinetics and also represent a potential nidus for infection, therefore requiring surgical removal. Absorbable cements have shown improved elution of a wider range of antibiotics and, crucially, complete biodegradation but limited data exist as to their antimicrobial and antibiofilm efficacy. Synthetic calcium sulfate beads loaded with tobramycin, vancomycin and a vancomycin &amp; tobramycin dual treatment (1:0.24 w/w ratio) were assessed for their ability to eradicate planktonic methicillin resistant S. aureus (MRSA) and S. epidermidis, relative to PMMA beads. The ability of the beads to prevent biofilm formation over multiple days and eradicate preformed biofilms was studied using a combination of viable cell counts, confocal microscopy and scanning electron microscopy of the bead surface. Biofilm bacteria displayed a greater tolerance to the antibiotics than their planktonic counterparts. Antibiotic-loaded beads were able to kill planktonic cultures of 106 CFU/mL, prevent bacterial colonisation and significantly reduce biofilm formation over multiple days. However, established biofilms were harder to eradicate. This data further demonstrates the difficulty in clearing established biofilms and therefore early preventative measures are key to reducing the risk of PI. Synthetic calcium sulfate loaded with antibiotics has the potential to reduce or eliminate biofilm formation on adjacent periprosthetic tissue and prosthesis material, and thus reduce rates of periprosthetic infection. <br/