Pretransitional phenomena in dilute crystals with first-order phase transition

Pretransitional phenomena at first-order phase transition in crystals diluted by 'neutral' impurities (analogue of nonmagnetic atoms in dilute magnets) are considered. It is shown that field dependence of order parameter becomes nonanalytical in the stability region of the ordered phase, while smeared jumps of thermodynamic parameters and anomalous (non-exponential) relaxation appear near transition temperature of pure crystal.Comment: 4 page

Novel Chikungunya Vaccine Candidate with an IRES-Based Attenuation and Host Range Alteration Mechanism

Chikungunya virus (CHIKV) is a reemerging mosquito-borne pathogen that has recently caused devastating urban epidemics of severe and sometimes chronic arthralgia. As with most other mosquito-borne viral diseases, control relies on reducing mosquito populations and their contact with people, which has been ineffective in most locations. Therefore, vaccines remain the best strategy to prevent most vector-borne diseases. Ideally, vaccines for diseases of resource-limited countries should combine low cost and single dose efficacy, yet induce rapid and long-lived immunity with negligible risk of serious adverse reactions. To develop such a vaccine to protect against chikungunya fever, we employed a rational attenuation mechanism that also prevents the infection of mosquito vectors. The internal ribosome entry site (IRES) from encephalomyocarditis virus replaced the subgenomic promoter in a cDNA CHIKV clone, thus altering the levels and host-specific mechanism of structural protein gene expression. Testing in both normal outbred and interferon response-defective mice indicated that the new vaccine candidate is highly attenuated, immunogenic and efficacious after a single dose. Furthermore, it is incapable of replicating in mosquito cells or infecting mosquitoes in vivo. This IRES-based attenuation platform technology may be useful for the predictable attenuation of any alphavirus

Targeted genome editing across species using ZFNs and TALENs

Evolutionary studies necessary to dissect diverse biological processes have been limited by the lack of reverse genetic approaches in most organisms with sequenced genomes. We established a broadly applicable strategy using zinc finger nucleases (ZFNs) and transcription activator-like effector nucleases (TALENs) for targeted disruption of endogenous genes and cis-acting regulatory elements in diverged nematode species

In C. elegans, High Levels of dsRNA Allow RNAi in the Absence of RDE-4

C. elegans Dicer requires an accessory double-stranded RNA binding protein, RDE-4, to enact the first step of RNA interference, the cleavage of dsRNA to produce siRNA. While RDE-4 is typically essential for RNAi, we report that in the presence of high concentrations of trigger dsRNA, rde-4 deficient animals are capable of silencing a transgene. By multiple criteria the silencing occurs by the canonical RNAi pathway. For example, silencing is RDE-1 dependent and exhibits a decrease in the targeted mRNA in response to an increase in siRNA. We also find that high concentrations of dsRNA trigger lead to increased accumulation of primary siRNAs, consistent with the existence of a rate-limiting step during the conversion of primary to secondary siRNAs. Our studies also revealed that transgene silencing occurs at low levels in the soma, even in the presence of ADARs, and that at least some siRNAs accumulate in a temperature-dependent manner. We conclude that an RNAi response varies with different conditions, and this may allow an organism to tailor a response to specific environmental signals

No Origin, No Problem for Yeast DNA Replication

Eukaryotic DNA replication initiates from multiple sites on each chromosome called replication origins (origins). In the budding yeast Saccharomyces cerevisiae, origins are defined at discrete sites. Regular spacing and diverse firing characteristics of origins are thought to be required for efficient completion of replication, especially in the presence of replication stress. However, a S. cerevisiae chromosome III harboring multiple origin deletions has been reported to replicate relatively normally, and yet how an origin-deficient chromosome could accomplish successful replication remains unknown. To address this issue, we deleted seven well-characterized origins from chromosome VI, and found that these deletions do not cause gross growth defects even in the presence of replication inhibitors. We demonstrated that the origin deletions do cause a strong decrease in the binding of the origin recognition complex. Unexpectedly, replication profiling of this chromosome showed that DNA replication initiates from non-canonical loci around deleted origins in yeast. These results suggest that replication initiation can be unexpectedly flexible in this organism

Identifying risks for male street gang affiliation: a systematic review and narrative synthesis

Gang violence has increased in recent years. Individuals are becoming gang affiliated younger, and many have suffered historic maltreatment. Subsequent exposure to violence can result in profound consequences, including acute psychological harm. This review aims to identify predictive risk factors for male street gang affiliation. A systematic literature search was conducted utilising PsycINFO, PsycARTICLES, Medline, the Cochrane Central Register of Controlled Trials, the Cochrane Database of Systematic Reviews and the Social Policy and Practice databases (from the databases’ inception to 03/04/15). From this search, n=244 peer-reviewed papers were included in an initial scoping review, and n=102 thereafter met criteria for a systematic review; a narrative synthesis follows. Gang members have typically faced numerous historic adversities across multiple domains; individual, family, peers, school and community. Cumulative factors generated an independent risk. The meta-narrative described an overarching failure to safeguard vulnerable individuals, with the motivation for gang affiliation hypothetically arising from an attempt to have their basic needs met. Clinical and research recommendations were made to inform early intervention policy and practice

Novel features of ARS selection in budding yeast Lachancea kluyveri

<p>Abstract</p> <p>Background</p> <p>The characterization of DNA replication origins in yeast has shed much light on the mechanisms of initiation of DNA replication. However, very little is known about the evolution of origins or the evolution of mechanisms through which origins are recognized by the initiation machinery. This lack of understanding is largely due to the vast evolutionary distances between model organisms in which origins have been examined.</p> <p>Results</p> <p>In this study we have isolated and characterized autonomously replicating sequences (ARSs) in <it>Lachancea kluyveri </it>- a pre-whole genome duplication (WGD) budding yeast. Through a combination of experimental work and rigorous computational analysis, we show that <it>L. kluyveri </it>ARSs require a sequence that is similar but much longer than the ARS Consensus Sequence well defined in <it>Saccharomyces cerevisiae</it>. Moreover, compared with <it>S. cerevisiae </it>and <it>K. lactis</it>, the replication licensing machinery in <it>L. kluyveri </it>seems more tolerant to variations in the ARS sequence composition. It is able to initiate replication from almost all <it>S. cerevisiae </it>ARSs tested and most <it>Kluyveromyces lactis </it>ARSs. In contrast, only about half of the <it>L. kluyveri </it>ARSs function in <it>S. cerevisiae </it>and less than 10% function in <it>K. lactis</it>.</p> <p>Conclusions</p> <p>Our findings demonstrate a replication initiation system with novel features and underscore the functional diversity within the budding yeasts. Furthermore, we have developed new approaches for analyzing biologically functional DNA sequences with ill-defined motifs.</p

Intracellular lumen extension requires ERM-1-dependent apical membrane expansion and AQP-8-mediated flux

SUMMARY Many unicellular tubes such as capillaries form lumens intracellularly, a process that is not well understood. Here we show that the cortical membrane organizer ERM-1 is required to expand the intracellular apical/lumenal membrane and its actin undercoat during single-cell C.elegans excretory canal morphogenesis. We characterize AQP-8, identified in an ERM-1 overexpression (ERM-1[++]) suppressor screen, as a canalicular aquaporin that interacts with ERM-1 in lumen extension in a mercury-sensitive manner, implicating water-channel activity. AQP-8 is transiently recruited to the lumen by ERM-1, co-localizing in peri-lumenal cuffs interspaced along expanding canals. An ERM-1[++]-mediated increase in the number of lumen-associated canaliculi is reversed by AQP-8 depletion. We propose that the ERM-1-AQP-8 interaction propels lumen extension by translumenal flux, suggesting a direct morphogenetic effect of water-channel-regulated fluid pressure

Differential Localization and Independent Acquisition of the H3K9me2 and H3K9me3 Chromatin Modifications in the Caenorhabditis elegans Adult Germ Line

Histone methylation is a prominent feature of eukaryotic chromatin that modulates multiple aspects of chromosome function. Methyl modification can occur on several different amino acid residues and in distinct mono-, di-, and tri-methyl states. However, the interplay among these distinct modification states is not well understood. Here we investigate the relationships between dimethyl and trimethyl modifications on lysine 9 of histone H3 (H3K9me2 and H3K9me3) in the adult Caenorhabditis elegans germ line. Simultaneous immunofluorescence reveals very different temporal/spatial localization patterns for H3K9me2 and H3K9me3. While H3K9me2 is enriched on unpaired sex chromosomes and undergoes dynamic changes as germ cells progress through meiotic prophase, we demonstrate here that H3K9me3 is not enriched on unpaired sex chromosomes and localizes to all chromosomes in all germ cells in adult hermaphrodites and until the primary spermatocyte stage in males. Moreover, high-copy transgene arrays carrying somatic-cell specific promoters are highly enriched for H3K9me3 (but not H3K9me2) and correlate with DAPI-faint chromatin domains. We further demonstrate that the H3K9me2 and H3K9me3 marks are acquired independently. MET-2, a member of the SETDB histone methyltransferase (HMTase) family, is required for all detectable germline H3K9me2 but is dispensable for H3K9me3 in adult germ cells. Conversely, we show that the HMTase MES-2, an E(z) homolog responsible for H3K27 methylation in adult germ cells, is required for much of the germline H3K9me3 but is dispensable for H3K9me2. Phenotypic analysis of met-2 mutants indicates that MET-2 is nonessential for fertility but inhibits ectopic germ cell proliferation and contributes to the fidelity of chromosome inheritance. Our demonstration of the differential localization and independent acquisition of H3K9me2 and H3K9me3 implies that the trimethyl modification of H3K9 is not built upon the dimethyl modification in this context. Further, these and other data support a model in which these two modifications function independently in adult C. elegans germ cells

Dynamic Chromatin Organization during Foregut Development Mediated by the Organ Selector Gene PHA-4/FoxA

Central regulators of cell fate, or selector genes, establish the identity of cells by direct regulation of large cohorts of genes. In Caenorhabditis elegans, foregut (or pharynx) identity relies on the FoxA transcription factor PHA-4, which activates different sets of target genes at various times and in diverse cellular environments. An outstanding question is how PHA-4 distinguishes between target genes for appropriate transcriptional control. We have used the Nuclear Spot Assay and GFP reporters to examine PHA-4 interactions with target promoters in living embryos and with single cell resolution. While PHA-4 was found throughout the digestive tract, binding and activation of pharyngeally expressed promoters was restricted to a subset of pharyngeal cells and excluded from the intestine. An RNAi screen of candidate nuclear factors identified emerin (emr-1) as a negative regulator of PHA-4 binding within the pharynx, but emr-1 did not modulate PHA-4 binding in the intestine. Upon promoter association, PHA-4 induced large-scale chromatin de-compaction, which, we hypothesize, may facilitate promoter access and productive transcription. Our results reveal two tiers of PHA-4 regulation. PHA-4 binding is prohibited in intestinal cells, preventing target gene expression in that organ. PHA-4 binding within the pharynx is limited by the nuclear lamina component EMR-1/emerin. The data suggest that association of PHA-4 with its targets is a regulated step that contributes to promoter selectivity during organ formation. We speculate that global re-organization of chromatin architecture upon PHA-4 binding promotes competence of pharyngeal gene transcription and, by extension, foregut development