The genetic insulator RiboJ increases expression of insulated genes

A primary objective of synthetic biology is the construction of genetic circuits with behaviors that can be predicted based on the properties of the constituent genetic parts from which they are built. However a significant issue in the construction of synthetic genetic circuits is a phenomenon known as context dependence in which the behavior of a given part changes depending on the choice of adjacent or nearby parts. Interactions between parts compromise the modularity of the circuit, impeding the implementation of predictable genetic constructs. To address this issue, investigators have devised genetic insulators that prevent these unintended context-dependent interactions between neighboring parts. One of the most commonly used insulators in bacterial systems is the self-cleaving ribozyme RiboJ. Despite its utility as an insulator, there has been no systematic quantitative assessment of the effect of RiboJ on the expression level of downstream genetic parts. Here, we characterized the impact of insulation with RiboJ on expression of a reporter gene driven by a promoter from a library of 24 frequently employed constitutive promoters in an Escherichia coli model system. We show that, depending on the strength of the promoter, insulation with RiboJ increased protein abundance between twofold and tenfold and increased transcript abundance by an average of twofold. This result demonstrates that genetic insulators in E. coli can impact the expression of downstream genes, information that is essential for the design of predictable genetic circuits and constructs

The genetic insulator RiboJ increases expression of insulated genes

A primary objective of synthetic biology is the construction of genetic circuits with behaviors that can be predicted based on the properties of the constituent genetic parts from which they are built. However a significant issue in the construction of synthetic genetic circuits is a phenomenon known as context dependence in which the behavior of a given part changes depending on the choice of adjacent or nearby parts. Interactions between parts compromise the modularity of the circuit, impeding the implementation of predictable genetic constructs. To address this issue, investigators have devised genetic insulators that prevent these unintended context-dependent interactions between neighboring parts. One of the most commonly used insulators in bacterial systems is the self-cleaving ribozyme RiboJ. Despite its utility as an insulator, there has been no systematic quantitative assessment of the effect of RiboJ on the expression level of downstream genetic parts. Here, we characterized the impact of insulation with RiboJ on expression of a reporter gene driven by a promoter from a library of 24 frequently employed constitutive promoters in an Escherichia coli model system. We show that, depending on the strength of the promoter, insulation with RiboJ increased protein abundance between twofold and tenfold and increased transcript abundance by an average of twofold. This result demonstrates that genetic insulators in E. coli can impact the expression of downstream genes, information that is essential for the design of predictable genetic circuits and constructs

Changing the Paradigm for Management of Pediatric Primary Spontaneous Pneumothorax: A Simple Aspiration Test Predicts Need for Operation

Purpose Chest tube (CT) management for pediatric primary spontaneous pneumothorax (PSP) is associated with long hospital stays and high recurrence rates. To streamline management, we explored simple aspiration as a test to predict need for surgery. Methods A multi-institution, prospective pilot study of patients with first presentation for PSP at 9 children’s hospitals was performed. Aspiration was performed through a pigtail catheter, followed by 6 h observation with CT clamped. If pneumothorax recurred during observation, the aspiration test failed and subsequent management was per surgeon discretion. Results Thirty-three patients were managed with simple aspiration. Aspiration was successful in 16 of 33 (48%), while 17 (52%) failed the aspiration test and required hospitalization. Twelve who failed aspiration underwent CT management, of which 10 (83%) failed CT management owing to either persistent air leak requiring VATS or subsequent PSP recurrence. Recurrence rate was significantly greater in the group that failed aspiration compared to the group that passed aspiration [10/12 (83%) vs 7/16 (44%), respectively, P = 0.028]. Conclusion Simple aspiration test upon presentation with PSP predicts chest tube failure with 83% positive predictive value. We recommend changing the PSP management algorithm to include an initial simple aspiration test, and if that fails, proceed directly to VATS

Screening practices and associated anomalies in infants with anorectal malformations: Results from the Midwest Pediatric Surgery Consortium

© 2018 Elsevier Inc. Background: This study evaluates screening practices and the incidence of associated anomalies in infants with anorectal malformations (ARM). Methods: We performed a multi-institutional retrospective cohort study of children born between 2007 and 2011 who underwent surgery for ARM at 10 children\u27s hospitals. ARM type was classified based on the location of the distal rectum, and all screening studies were reviewed. Results: Among 506 patients, the most common ARM subtypes were perineal fistula (40.7%), no fistula (11.5%), and vestibular fistula (10.1%). At least 1 screening test was performed in 96.6% of patients, and 11.3% of patients underwent all. The proportion of patients with ≥ 1 abnormal finding on any screening test varied by type of ARM (p \u3c 0.001). Screening rates varied from 15.2% for limb anomalies to 89.7% for renal anomalies. The most commonly identified anomalies by screening category were: spinal: tethered cord (20.6%); vertebral: sacral dysplasia/hemisacrum (17.8%); cardiac: patent foramen ovale (58.0%); renal: hydronephrosis (22.7%); limb: absent radius (7.9%). Conclusion: Screening practices and the incidence of associated anomalies varied by type of ARM. The rate of identifying at least one associated anomaly was high across all ARM subtypes. Screening for associated anomalies should be considered standard of care for all ARM patients. Type of study: Multi-institutional retrospective cohort study. Level of evidence: II