Summary Flagellar type III secretion systems (T3SS) contain an essential cytoplasmic-ring (C-ring) largely composed of two proteins FliM and FliN, whereas an analogous substructure for the closely ...related non-flagellar (NF) T3SS has not been observed in situ. We show that the spa33 gene encoding the putative NF-T3SS C-ring component in Shigella flexneri is alternatively translated to produce both full-length (Spa33-FL) and a short variant (Spa33-C), with both required for secretion. They associate in a 1:2 complex (Spa33-FL/C2) that further oligomerises into elongated arrays in vitro. The structure of Spa33-C2 and identification of an unexpected intramolecular pseudodimer in Spa33-FL reveal a molecular model for their higher order assembly within NF-T3SS. Spa33-FL and Spa33-C are identified as functional counterparts of a FliM-FliN fusion and free FliN respectively. Furthermore, we show that Thermotoga maritimaFliM and FliN form a 1:3 complex structurally equivalent to Spa33-FL/C2, allowing us to propose a unified model for C-ring assembly by NF-T3SS and flagellar-T3SS.
Constraint-induced movement therapy is a set of treatments for rehabilitating motor function after central nervous system damage. We assessed the roles of its 2 main components.
A 2 × 2 factorial ...components analysis with random assignment was conducted. The 2 factors were type of training and presence/absence of a set of techniques to facilitate transfer of therapeutic gains from the laboratory to the life situation (Transfer Package; TP). Participants (N=40) were outpatients ≥ 1-year after stroke with hemiparesis. The different treatments, which in each case targeted the more affected arm, lasted 3.5 hours/d for 10 weekdays. Spontaneous use of the more affected arm in daily life and maximum motor capacity of that arm in the laboratory were assessed with the Motor Activity Log and the Wolf Motor Function Test, respectively.
Use of the TP, regardless of the type of training received, resulted in Motor Activity Log gains that were 2.4 times as large as the gains in its absence (P<0.01). These clinical results parallel previously reported effects of the TP on neuroplastic change. Both the TP and training by shaping enhanced gains on the Wolf Motor Function Test (P<0.05). The Motor Activity Log gains were retained without loss 1 year after treatment. An additional substudy (N=10) showed that a single component of the TP, weekly telephone contact with participants for 1 month after treatment, doubled Motor Activity Log scores at 6-month follow-up.
The TP is a method for enhancing both spontaneous use of a more affected arm after chronic stroke and its maximum motor capacity. Shaping enhances the latter.
Oxidative and nitrosative stresses including nitric oxide (NO), superoxide (O2⁻) and peroxynitrite play key roles in determining the outcome of bacterial infections. In order to survive within the ...host and allow proliferation within immune cells such as macrophages, Salmonella isolates have a number of inducible proteins that are able to detoxify these highly reactive species, notably the anoxically functioning NO reductase NorVW, and the aerobically functioning flavohaemoglobin, Hmp, which catalyses the reaction between oxygen and NO to produce relatively inert nitrate. However, in the absence of NO but in the presence of reducing substrates and oxygen, O2⁻ is generated from Hmp-mediated electron transfer to bound oxygen and may form a variety of further oxidative species. Hence, Hmp expression is under tight negative regulation by the transcription factor NsrR, abolition of which causes an increase in the production of Hmp. In a previous study, this increase in Hmp levels conferred resistance to the nitrosating agent S-nitrosoglutathione but, perhaps surprisingly, the organism became more sensitive to killing by macrophages. Here, we report that an nsrR mutant that constitutively overexpresses Hmp is also hypersensitive to peroxynitrite in vitro. This sensitivity is alleviated by deletion of the hmp gene or pre-incubation of growing bacteria with NO-releasing agents. We hypothesize that Hmp-expressing cells, in the absence of NO, generate reactive oxygen species, the toxicity of which is exacerbated by peroxynitrite in vitro and in macrophages. RT-PCR confirmed that peroxynitrite causes oxidative stress and upregulation of katG and ahpC, whilst hmp and norV expression are affected very little. The katG gene upregulated by peroxynitrite encodes a catalase peroxidase enzyme with well-established roles in detoxifying peroxides. Here, we report that KatG is also able to enhance the breakdown of peroxynitrite, suggesting that the protective role of this enzyme may be wider than previously thought. These data suggest that spatial and temporal fluctuations in the levels of NO and reactive oxygen species will have important consequences for bacterial survival in the macrophage.
Many biotechnological applications require high-level expression of transgenes in plants. One strategy to achieve this goal was the production of potato virus X (PVX) "amplicon" lines: transgenic ...lines that encode a replicating RNA virus vector carrying a gene of interest. The idea was that transcription of the amplicon transgene would initiate viral RNA replication and gene expression, resulting in very high levels of the gene product of interest. This approach failed, however, because every amplicon transgene, in both tobacco and Arabidopsis thaliana, was subject to post-transcriptional gene silencing (PTGS). In PTGS, the transgene is transcribed but the transcripts fail to accumulate as a result of sequence-specific targeting and destruction. Even though the amplicon locus is silenced, the level of beta-glucuronidase (GUS) activity in a PVX/GUS line is similar to that in some transgenic lines expressing GUS from a conventional (not silenced) GUS locus. This result suggested that the very high levels of expression originally envisioned for amplicons could be achieved if PTGS could be overcome and if the resulting plants did not suffer from severe viral disease. Here we report that high-level transgene expression can be achieved by pairing the amplicon approach with the use of a viral suppressor of PTGS, tobacco etch virus (TEV) helper component proteinase (HC-Pro). Leaves of mature tobacco plants co-expressing HC-Pro and a PVX/GUS amplicon accumulate GUS to approximately 3% of total protein. Moreover, high-level expression occurs without viral symptoms and, when HC-Pro is expressed from a mutant transgene, without detrimental developmental phenotypes.
We tested the hypothesis that the H(2)-based membrane biofilm reactor (MBfR) is capable of reducing multiple oxidized contaminants, a common situation for groundwater contamination. We conducted ...bench-scale experiments with three groundwater samples collected from California's San Joaquin Valley and on two synthetic groundwaters containing selenate and chromate. The actual groundwater sources had nitrate levels exceeding 10 mg-N l(-1) and different combinations of anthropogenic perchlorate + chlorate, arsenate, and dibromochloropropane (DBCP). For all actual groundwaters, the MBfR reduced nitrate to less than 0.01 mg-N l(-1). Present in two groundwaters, perchlorate + chlorate was reduced to below the California Notification Level, 6 microg-ClO(4) l(-1). As(V) was substantially reduced to As(III) for two groundwaters samples, which had influent As(V) concentrations from 3 to 8.8 microg-As l(-1). DBCP, present in one groundwater at 1.4 microg l(-1), was reduced to below its detection limit of 0.01 microg l(-1), which is well below California's 0.2 microg l(-1) MCL for DBCP. For the synthetic groundwaters, two MBfRs initially reduced Se(VI) or Cr(VI) stably to Se degrees or Cr(III). When we switched the influent oxidized contaminants, the new oxidized contaminant was reduced immediately, and its reduction soon was approximately the same or greater than it had been reduced in its original MBfR. These results support that the H(2)-based MBfR can reduce multiple oxidized contaminants simultaneously.
Research on perceptions of sanction severity reveals a gap between White and Black respondents in terms of their preferences for incarceration compared to alternative punishments. Little is known, ...however, about Latinx preferences. Using a sample of jail inmates, we explore differences across White, Black, and Latinx respondents in terms of their preferences for incarceration versus probation, as well as the factors that relate to these preferences. Findings show that White respondents prefer probation far more frequently than Black and Latinx respondents. Additionally, factors which relate to sanctioning preferences for Whites are fundamentally different than those for Black and Latinx adults.
As we age, our bones undergo a process of loss, often accompanied by muscle weakness and reduced physical activity. This is exacerbated by decreased responsiveness to mechanical stimulation in aged ...skeleton, leading to the hypothesis that decreased mechanical stimulation plays an important role in age‐related bone loss. Piezo1, a mechanosensitive ion channel, is critical for bone homeostasis and mechanotransduction. Here, we observed a decrease in Piezo1 expression with age in both murine and human cortical bone. Furthermore, loss of Piezo1 in osteoblasts and osteocytes resulted in an increase in age‐associated cortical bone loss compared to control mice. The loss of cortical bone was due to an expansion of the endosteal perimeter resulting from increased endocortical resorption. In addition, expression of Tnfrsf11b, encoding anti‐osteoclastogenic protein OPG, decreases with Piezo1 in vitro and in vivo in bone cells, suggesting that Piezo1 suppresses osteoclast formation by promoting Tnfrsf11b expression. Our results highlight the importance of Piezo1‐mediated mechanical signaling in protecting against age‐associated cortical bone loss by inhibiting bone resorption in mice.
Age‐related bone loss is associated with decreased expression of Piezo1, a mechanosensitive ion channel, and osteoprotegerin (OPG), an osteoclastogenesis inhibitory factor. Loss of Piezo1 signaling in osteoblasts and osteocytes exacerbates cortical bone loss in old mice by enhancing osteoclast formation in endocortical bone surface. Our results indicate the importance of Piezo1‐mediated signaling in protecting against age‐associated cortical bone loss.
The Iowa Gambling Task (
Bechara, Damasio, Damasio, & Anderson, 1994) is an effective neuropsychological tool for the assessment of ‘real-life’ decision-making in a laboratory environment. It has ...been employed in a wide range of circumstances, though researchers have sometimes employed
real money reinforcers instead of the facsimile (or ‘monopoly’-type) money used by
Bechara et al. (1994). The present study investigated whether the type of reinforcer produced any differences in performance. There were no significant differences between the two conditions, though the Facsimile Money condition produced a greater range (and a higher standard deviation) than the Real Money condition. This finding is especially important when considering the Gambling Task as a tool in clinical neuropsychology—where there are risks, at the individual subject level, of both false positive and false negative classification errors.
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