Chromatin profiling identifies putative dual roles for H3K27me3 in regulating transposons and cell type-specific genes in choanoflagellates.

Gene expression is tightly controlled during animal development to allow the formation of specialized cell types. Our understanding of how animals evolved this exquisite regulatory control remains elusive, but evidence suggests that changes in chromatin-based mechanisms may have contributed. To investigate this possibility, here we examine chromatin-based gene regulatory features in the closest relatives of animals, choanoflagellates. Using Salpingoeca rosetta as a model system, we examined chromatin accessibility and histone modifications at the genome scale and compared these features to gene expression. We first observed that accessible regions of chromatin are primarily associated with gene promoters and found no evidence of distal gene regulatory elements resembling the enhancers that animals deploy to regulate developmental gene expression. Remarkably, a histone modification deposited by polycomb repressive complex 2, histone H3 lysine 27 trimethylation (H3K27me3), appeared to function similarly in S. rosetta to its role in animals, because this modification decorated genes with cell type-specific expression. Additionally, H3K27me3 marked transposons, retaining what appears to be an ancestral role in regulating these elements. We further uncovered a putative new bivalent chromatin state at cell type-specific genes that consists of H3K27me3 and histone H3 lysine 4 mono-methylation (H3K4me1). Together, our discoveries support the scenario that gene-associated histone modification states that underpin development emerged before the evolution of animal multicellularity.

Treatment with Brivudine in Immunocompromised Pediatric Patients with Herpes Zoster.

INTRODUCTION: Herpes zoster (HZ) is caused by endogenous reactivation of latent varicella-zoster virus (VZV) that persists in sensory ganglia after primary infection. The incidence and severity of HZ increase during immunosuppression. Especially, immunocompromised patients are at high risk of developing a cutaneous rash and suffering from delayed healing of lesions. Bromovinyl deoxyuridine (brivudine), one of the most potent oral inhibitors of VZV replication, is widely used in the therapy of HZ in adult patients, particularly in Europe. In this study, we investigated the efficacy of brivudine in immunocompromised children to provide an outpatient treatment option. METHODS: In this retrospective study, we included 64 immunocompromised pediatric patients with a median age of 14 years. Forty-seven patients received immunosuppressive therapy as part of hematopoietic stem cell transplantation and 17 patients as part of chemotherapy. Primary diagnosis was made clinically by examining the nature and the localization of the skin lesions. Laboratory confirmation was conducted based on the detection of VZV DNA in vesicle fluid and blood samples. Brivudine was administered orally at a single dose of 2 mg/kg per day. We monitored the patients' response for the full time of treatment and observed the time of full crusting of lesions, loss of crusts, and any adverse effects that occurred. RESULTS: Patients received medication for 7-21 days (median: 14 days). All children responded promptly to antiviral treatment and recovered completely from their HZ infections without complications. Crusting of lesions was reached after 3-14 days (median: 6 days). Full healing of skin lesions was ascertained within 7-21 days (median: 12 days). Overall, brivudine therapy was well tolerated. No clinical side effects during or after the treatment were observed. High compliance was achieved due to the once-daily dosing regimen. All patients were treated in an outpatient manner. CONCLUSION: Oral brivudine was a very effective and well-tolerated therapy in immunocompromised children with HZ infection. The oral administration offers the potential for outpatient treatment of HZ in these patients.

Association of recipient and donor interleukin 6 polymorphisms 174 and 597 with outcome after allogeneic hematopoietic stem cell transplantation in children.

PURPOSE: The success of allogeneic hematopoietic stem cell transplantation (HSCT) is compromised by complications such as infection, relapse, and graft-versus-host disease (GVHD). The investigation of non-HLA immunogenetics, particularly of cytokines, could identify predictors of an unfavorable outcome after allogeneic HSCT. In this study, we examined the impact of single nucleotide polymorphisms (SNPs) within the promoter region of interleukin 6 (IL6) on the development of GVHD after pediatric allogeneic HSCT. METHODS: In this retrospective analysis, we included 320 pediatric patients with a median age of 10 years who underwent an allogeneic HSCT and their respective donors. We used TaqMan real-time polymerase chain reaction to analyze the SNPs IL6-174 (G/C) and IL6-597 (G/A). The IL6-174 polymorphism was examined in 300 recipients and 295 donors. The IL6-597 polymorphism was analyzed in 299 recipients and 296 donors. We investigated the influence of the IL6-174 and IL6-597 polymorphisms on overall survival, event-free survival, relapse incidence, transplant-related mortality, and the occurrence of GVHD. RESULTS: G polymorphism at position 174 of the recipient IL6 gene was associated with a higher incidence of acute GVHD (GG vs. GC/CC; P = 0.024). Patients with IL6-597 GG genotype developed acute GVHD more frequently than individuals with an A allele (GG vs. GA vs. AA; P = 0.013). IL6-174 GG homozygous recipients had a more frequent occurrence of chronic GVHD (GG vs. GC/CC; P = 0.049). We observed a significant increased risk of chronic GVHD in recipients with IL6-597 GG genotype (GG vs. GA vs. AA; P = 0.043). Polymorphisms of donors did not affect the incidence of acute GVHD and chronic GVHD. In multivariate analysis, the IL6-174 and IL6-597 SNPs were independent significant risk factors for acute GVHD (P = 0.030; P = 0.007, respectively) as well as for chronic GVHD (P = 0.045; P = 0.015, respectively). In addition, older age at time of transplantation turned out to be a significant risk factor for chronic GVHD (P = 0.003). CONCLUSION: Our study identified the IL6-174 and IL6-597 GG genotypes of pediatric allogeneic HSCT recipients as genetic risk factors for the development of acute GVHD and chronic GVHD. After evaluations in further studies, these findings could implicate the adjustment of prophylactic measures to reduce the occurrence of acute GVHD and chronic GVHD.

Centrin2 from the human parasite Toxoplasma gondii is required for its invasion and intracellular replication.

Centrins are EF-hand containing proteins ubiquitously found in eukaryotes and are key components of centrioles/basal bodies as well as certain contractile fibers. We previously identified three centrins in the human parasite Toxoplasma gondii, all of which localized to the centrioles. However, one of them, T. gondii (Tg) Centrin2 (CEN2), is also targeted to structures at the apical and basal ends of the parasite, as well as to annuli at the base of the apical cap of the membrane cortex. The role(s) that CEN2 play in these locations were unknown. Here, we report the functional characterization of CEN2 using a conditional knockdown method that combines transcriptional and protein stability control. The knockdown resulted in an ordered loss of CEN2 from its four compartments, due to differences in incorporation kinetics and structural inheritance over successive generations. This was correlated with a major invasion deficiency at early stages of CEN2 knockdown, and replication defects at later stages. These results indicate that CEN2 is incorporated into multiple cytoskeletal structures to serve distinct functions that are required for parasite survival.

Predicted glycosyltransferases promote development and prevent spurious cell clumping in the choanoflagellate S. rosetta.

In a previous study we established forward genetics in the choanoflagellate Salpingoeca rosetta and found that a C-type lectin gene is required for rosette development (Levin et al., 2014). Here we report on critical improvements to genetic screens in S. rosetta while also investigating the genetic basis for rosette defect mutants in which single cells fail to develop into orderly rosettes and instead aggregate promiscuously into amorphous clumps of cells. Two of the mutants, Jumble and Couscous, mapped to lesions in genes encoding two different predicted glycosyltransferases and displayed aberrant glycosylation patterns in the basal extracellular matrix (ECM). In animals, glycosyltransferases sculpt the polysaccharide-rich ECM, regulate integrin and cadherin activity, and, when disrupted, contribute to tumorigenesis. The finding that predicted glycosyltransferases promote proper rosette development and prevent cell aggregation in S. rosetta suggests a pre-metazoan role for glycosyltransferases in regulating development and preventing abnormal tumor-like multicellularity.

The Rosetteless gene controls development in the choanoflagellate S. rosetta.

The origin of animal multicellularity may be reconstructed by comparing animals with one of their closest living relatives, the choanoflagellate Salpingoeca rosetta. Just as animals develop from a single cell-the zygote-multicellular rosettes of S. rosetta develop from a founding cell. To investigate rosette development, we established forward genetics in S. rosetta. We find that the rosette defect of one mutant, named Rosetteless, maps to a predicted C-type lectin, a class of signaling and adhesion genes required for the development and innate immunity in animals. Rosetteless protein is essential for rosette development and forms an extracellular layer that coats and connects the basal poles of each cell in rosettes. This study provides the first link between genotype and phenotype in choanoflagellates and raises the possibility that a protein with C-type lectin-like domains regulated development in the last common ancestor of choanoflagellates and animals.

Novel thioredoxin-like proteins are components of a protein complex coating the cortical microtubules of Toxoplasma gondii.

Microtubules are versatile biopolymers that support numerous vital cellular functions in eukaryotes. The specific properties of microtubules are dependent on distinct microtubule-associated proteins, as the tubulin subunits and microtubule structure are exceptionally conserved. Highly specialized microtubule-containing assemblies are often found in protists, which are rich sources for novel microtubule-associated proteins. A protozoan parasite, Toxoplasma gondii, possesses several distinct tubulin-containing structures, including 22 microtubules closely associated with the cortical membrane. Early ultrastructural studies have shown that the cortical microtubules are heavily decorated with associating proteins. However, little is known about the identities of these proteins. Here, we report the discovery of a novel protein, TrxL1 (for Thioredoxin-Like protein 1), and an associating complex that coats the cortical microtubules. TrxL1 contains a thioredoxin-like fold. To visualize its localization in live parasites by fluorescence, we replaced the endogenous TrxL1 gene with an mEmeraldFP-TrxL1 fusion gene. Structured illumination-based superresolution imaging of this parasite line produced a detailed view of the microtubule cytoskeleton. Despite its stable association with the cortical microtubules in the parasite, TrxL1 does not seem to bind to microtubules directly. Coimmunoprecipitation experiments showed that TrxL1 associates with a protein complex containing SPM1, a previously reported microtubule-associated protein in T. gondii. We also found that SPM1 recruits TrxL1 to the cortical microtubules. Besides SPM1, several other novel proteins are found in the TrxL1-containing complex, including TrxL2, a close homolog of TrxL1. Thus, our results reveal for the first time a microtubule-associated complex in T. gondii.

Quality of colonoscopy withdrawal technique and variability in adenoma detection rates (with videos).

BACKGROUND: Studies suggest that endoscopist-related factors such as colonoscopy withdrawal time are important in determining the adenoma detection rate (ADR). OBJECTIVE: To determine the importance of withdrawal technique in differentiating among endoscopists with varying ADRs. DESIGN: Prospective, multicenter study. SETTING: Five academic tertiary-care medical centers. PARTICIPANTS: This study involved 11 gastroenterology faculty endoscopists. INTERVENTION: A retrospective review of screening colonoscopies was performed to categorize endoscopists into low, moderate, and high ADR groups. Video recordings were randomly obtained for each endoscopist on 20 (10 real, 10 sham) withdrawals during colonoscopies performed for average-risk colorectal cancer screening. Three blinded reviewers assigned withdrawal technique scores (total of 75 points) on 110 video recordings. A separate reviewer recorded withdrawal times. MAIN OUTCOME MEASUREMENTS: Withdrawal technique scores and withdrawal times. RESULTS: Mean (± standard deviation [SD]) withdrawal technique scores were higher in the moderate (62 ± 2.5) and high (59.5 ± 3) ADR groups compared with the low (40.8±3) ADR group (P = .002). Mean (± SD) withdrawal times were 6.3 ± 1.8 minutes (low ADR), 10.2 ± 1.5 minutes (moderate ADR), and 8.2 ± 1.8 minutes (high ADR) (P = .29). A comparison of the withdrawal times and technique scores of the two individual endoscopists with the lowest and highest ADRs did not find a significant difference in withdrawal times (6.6 ± 1.7 vs 7.4 ± 1.7 minutes) (P = .36) but did find a nearly 2-fold difference in technique scores (36.2 ± 9 vs 62.8 ± 9.9) (P = .0001). LIMITATIONS: Not adequately powered to detect small differences in withdrawal times. CONCLUSION: Withdrawal technique is an important indicator that differentiates between endoscopists with varying ADRs. It is possible that withdrawal technique is equal to, if not more important than, withdrawal time in determining ADRs.

MCAK and paclitaxel have differential effects on spindle microtubule organization and dynamics.

Within the mitotic spindle, there are multiple populations of microtubules with different turnover dynamics, but how these different dynamics are maintained is not fully understood. MCAK is a member of the kinesin-13 family of microtubule-destabilizing enzymes that is required for proper establishment and maintenance of the spindle. Using quantitative immunofluorescence and fluorescence recovery after photobleaching, we compared the differences in spindle organization caused by global suppression of microtubule dynamics, by treating cells with low levels of paclitaxel, versus specific perturbation of spindle microtubule subsets by MCAK inhibition. Paclitaxel treatment caused a disruption in spindle microtubule organization marked by a significant increase in microtubules near the poles and a reduction in K-fiber fluorescence intensity. This was correlated with a faster t(1/2) of both spindle and K-fiber microtubules. In contrast, MCAK inhibition caused a dramatic reorganization of spindle microtubules with a significant increase in astral microtubules and reduction in K-fiber fluorescence intensity, which correlated with a slower t(1/2) of K-fibers but no change in the t(1/2) of spindle microtubules. Our data support the model that MCAK perturbs spindle organization by acting preferentially on a subset of microtubules, and they support the overall hypothesis that microtubule dynamics is differentially regulated in the spindle.

The effectiveness of 4% intracuff lidocaine in reducing coughing during emergence from general anesthesia in smokers undergoing procedures lasting less than 1.5 hours.

Coughing commonly occurs in patients emerging from general endotracheal anesthesia and is prominent in smokers due to underlying airway irritation. Clinical techniques used to mitigate emergence coughing include intravenous narcotics, intravenous or topical lidocaine, and deep extubation. Reduction of coughing by instilling lidocaine into the endotracheal tube cuff has been shown to be effective in long cases. Research has not confirmed efficacy of this technique in short cases. Does administration of intracuff lidocaine decrease coughing during emergence of smokers in short cases requiring general endotracheal anesthesia? This study was a randomized, double blind, posttest-only design that included 38 patients. Investigators recruited the subjects, obtained consent, and provided a syringe containing 5 mL of 4% lidocaine or 5 mL of saline to the anesthesia provider. At time of intubation, the provider injected the contents of the syringe into the endotracheal tube cuff. The control group received 5 mL of saline, and the experimental group received 5 mL of 4% lidocaine. On emergence, the anesthesia provider counted and recorded the number of coughs before awake extubation. This study did not show a correlation between use of intracuff lidocaine and a decrease in emergence coughing in procedures lasting less than 1.5 hours in patients who smoke.