Dynamics of Dynamin during Clathrin Mediated Endocytosis in PC12 Cells

Members of the dynamin super-family of GTPases are involved in disparate cellular pathways. Dynamin1 and dynamin2 have been implicated in clathrin-mediated endocytosis. While some models suggest that dynamin functions specifically at the point of vesicle fission, evidence also exists for a role prior to fission during vesicle formation and it is unknown if there is a role for dynamin after vesicle fission. Although dynamin2 is ubiquitously expressed, dynamin1 is restricted to the nervous system. These two structurally similar endocytic accessory proteins have not been studied in cells that endogenously express both.The present study quantitatively assesses the dynamics of dynamin1 and dynamin2 during clathrin-mediated endocytosis in PC12 cells, which endogenously express both proteins. Both dynamin isoforms co-localized with clathrin and showed sharp increases in fluorescence intensity immediately prior to internalization of the nascent clathrin-coated vesicle. The fluorescence intensity of both proteins then decreased with two time constants. The slower time constant closely matched the time constant for the decrease of clathrin intensity and likely represents vesicle movement away from the membrane. The faster rate may reflect release of dynamin at the neck of nascent vesicle following GTP hydrolysis.This study analyses the role of dynamin in clathrin-mediated endocytosis in a model for cellular neuroscience and these results may provide direct evidence for the existence of two populations of dynamin associated with nascent clathrin-coated vesicles

Re-localization of Cellular Protein SRp20 during Poliovirus Infection: Bridging a Viral IRES to the Host Cell Translation Apparatus

Poliovirus IRES-mediated translation requires the functions of certain canonical as well as non-canonical factors for the recruitment of ribosomes to the viral RNA. The interaction of cellular proteins PCBP2 and SRp20 in extracts from poliovirus-infected cells has been previously described, and these two proteins were shown to function synergistically in viral translation. To further define the mechanism of ribosome recruitment for the initiation of poliovirus IRES-dependent translation, we focused on the role of the interaction between cellular proteins PCBP2 and SRp20. Work described here demonstrates that SRp20 dramatically re-localizes from the nucleus to the cytoplasm of poliovirus-infected neuroblastoma cells during the course of infection. Importantly, SRp20 partially co-localizes with PCBP2 in the cytoplasm of infected cells, corroborating our previous in vitro interaction data. In addition, the data presented implicate the presence of these two proteins in viral translation initiation complexes. We show that in extracts from poliovirus-infected cells, SRp20 is associated with PCBP2 bound to poliovirus RNA, indicating that this interaction occurs on the viral RNA. Finally, we generated a mutated version of SRp20 lacking the RNA recognition motif (SRp20ΔRRM) and found that this protein is localized similar to the full length SRp20, and also partially co-localizes with PCBP2 during poliovirus infection. Expression of this mutated version of SRp20 results in a ∼100 fold decrease in virus yield for poliovirus when compared to expression of wild type SRp20, possibly via a dominant negative effect. Taken together, these results are consistent with a model in which SRp20 interacts with PCBP2 bound to the viral RNA, and this interaction functions to recruit ribosomes to the viral RNA in a direct or indirect manner, with the participation of additional protein-protein or protein-RNA interactions

Effects of nutrient addition and soil drainage on germination of N-fixing and non-N-fixing tropical dry forest tree species

To develop generalised predictions regarding the effects of atmospheric nitrogen (N) and phosphorus (P) deposition on vegetation communities, it is necessary to account for the impacts of increased nutrient availability on the early life history stages of plants. Additionally, it is important to determine if these responses (a) differ between plant functional groups and (b) are modulated by soil drainage, which may affect the persistence of added nutrients. We experimentally assessed seed germination responses (germination proportion and germination energy, i.e. time to germination) of commonly occurring N-fixing and non-N-fixing tropical dry forest tree species found in India to simulated N and P deposition in well-drained soils, as well as soils with impeded drainage. When soils were not allowed to drain, germination proportion declined with nutrient addition, while germination energy remained unchanged. Stronger declines in germination proportion were observed for N-fixing species. In free-draining soils, nutrient addition did not affect germination proportion in either functional group. However, we detected a trend of delayed germination with nutrient addition, especially in N-fixers. Our results suggest that nutrient deposition can lead to potential shifts in functional dominance and tree community composition of tropical dry forests in the long term through its effects on early life stages of trees, although the mechanisms underlying the observed germination responses remain unclear. Further, such effects are likely to be spatially variable across the geographic range in which tropical dry forests occur depending on soil drainage properties

Efficacy and safety of aripiprazole in the treatment of bipolar disorder: a systematic review

Abstract BACKGROUND: The current article is a systematic review concerning the efficacy and safety of aripiprazole in the treatment of bipolar disorder. METHODS: A systematic Medline and repositories search concerning the usefulness of aripiprazole in bipolar disorder was performed, with the combination of the words 'aripiprazole' and 'bipolar'. RESULTS: The search returned 184 articles and was last updated on 15 April 2009. An additional search included repositories of clinical trials and previous systematic reviews specifically in order to trace unpublished trials. There were seven placebo-controlled randomised controlled trials (RCTs), six with comparator studies and one with add-on studies. They assessed the usefulness of aripiprazole in acute mania, acute bipolar depression and during the maintenance phase in comparison to placebo, lithium or haloperidol. CONCLUSION: Aripiprazole appears effective for the treatment and prophylaxis against mania. The data on bipolar depression are so far negative, however there is a need for further study at lower dosages. The most frequent adverse effects are extrapyramidal signs and symptoms, especially akathisia, without any significant weight gain, hyperprolactinaemia or laboratory test changes

ICF, An Immunodeficiency Syndrome: DNA Methyltransferase 3B Involvement, Chromosome Anomalies, and Gene Dysregulation

The immunodeficiency, centromeric region instability, and facial anomalies syndrome (ICF) is the only disease known to result from a mutated DNA methyltransferase gene, namely, DNMT3B. Characteristic of this recessive disease are decreases in serum immunoglobulins despite the presence of B cells and, in the juxtacentromeric heterochromatin of chromosomes 1 and 16, chromatin decondensation, distinctive rearrangements, and satellite DNA hypomethylation. Although DNMT3B is involved in specific associations with histone deacetylases, HP1, other DNMTs, chromatin remodelling proteins, condensin, and other nuclear proteins, it is probably the partial loss of catalytic activity that is responsible for the disease. In microarray experiments and real-time RT-PCR assays, we observed significant differences in RNA levels from ICF vs. control lymphoblasts for pro- and anti-apoptotic genes (BCL2L10, CASP1, and PTPN13); nitrous oxide, carbon monoxide, NF-κB, and TNFa signalling pathway genes (PRKCH, GUCY1A3, GUCY1B3, MAPK13; HMOX1, and MAP4K4); and transcription control genes (NR2F2 and SMARCA2). This gene dysregulation could contribute to the immunodeficiency and other symptoms of ICF and might result from the limited losses of DNA methylation although ICF-related promoter hypomethylation was not observed for six of the above examined genes. We propose that hypomethylation of satellite 2at1qh and 16qh might provoke this dysregulation gene expression by trans effects from altered sequestration of transcription factors, changes in nuclear architecture, or expression of noncoding RNAs

Qualitative evaluation of a preventive intervention for the offspring of parents with a history of depression

Background: Meta-analyses of randomised controlled trials suggest that psychological interventions to reduce children’s risk of depression are effective. Nevertheless, these effects are modest and diminish over time. The Medical Research Council recommends a mixed-methods approach to the evaluation of complex interventions. By gaining a more thorough understanding of participants’ perspectives, qualitative evaluations of preventive interventions could improve their efficacy, longevity and transfer into clinical practice. Methods: 18 parents and 22 children who had received a 12-session family- and group-based cognitivebehavioural intervention to prevent youth depression as part of a randomised controlled trial took part in semistructured interviews or a focus group about aspects which had been perceived as helpful, elements they were still using after the intervention had ended, and suggestions they had for improving the intervention. Results: The chance to openly share and discuss their experiences of depression within and between families was considered helpful by both children and parents. Children benefitted the most from learning coping strategies for dealing with stress and many still used them in everyday life. Parents profited mostly from increasing positive family time, but noted that maintaining new routines after the end of the intervention proved difficult. Participants were generally content with the intervention but commented on how tiring and time consuming it was. Conclusions: Managing parents’ expectations of family-based interventions in terms of their own mental health needs (versus those of their children) and leaving more room for open discussions may result in interventions which are more appealing to participating families. Increasing intervals between sessions may be one means of improving the longevity of interventions. Trial registration: The original RCT this evaluation is a part of was registered under NCT02115880

Information structure influences depth of syntactic processing: Event-related potential evidence for the Chomsky illusion

Contains fulltext : 102636.pdf (publisher's version ) (Open Access)Information structure facilitates communication between interlocutors by highlighting relevant information. It has previously been shown that information structure modulates the depth of semantic processing. Here we used event-related potentials to investigate whether information structure can modulate the depth of syntactic processing. In question-answer pairs, subtle (number agreement) or salient (phrase structure) syntactic violations were placed either in focus or out of focus through information structure marking. P600 effects to these violations reflect the depth of syntactic processing. For subtle violations, a P600 effect was observed in the focus condition, but not in the non-focus condition. For salient violations, comparable P600 effects were found in both conditions. These results indicate that information structure can modulate the depth of syntactic processing, but that this effect depends on the salience of the information. When subtle violations are not in focus, they are processed less elaborately. We label this phenomenon the Chomsky illusion.9 p