Development of a genetic toolset for the highly engineerable and metabolically versatile Acinetobacter baylyi ADP1

One primary objective of synthetic biology is to improve the sustainability of chemical manufacturing. Naturally occurring biological systems can utilize a variety of carbon sources, including waste streams that pose challenges to traditional chemical processing, such as lignin biomass, providing opportunity for remediation and valorization of these materials. Success, however, depends on identifying micro-organisms that are both metabolically versatile and engineerable. Identifying organisms with this combination of traits has been a historic hindrance. Here, we leverage the facile genetics of the metabolically versatile bacterium Acinetobacter baylyi ADP1 to create easy and rapid molecular cloning workflows, including a Cas9-based single-step marker-less and scar-less genomic integration method. In addition, we create a promoter library, ribosomal binding site (RBS) variants and test an unprecedented number of rationally integrated bacterial chromosomal protein expression sites and variants. At last, we demonstrate the utility of these tools by examining ADP1’s catabolic repression regulation, creating a strain with improved potential for lignin bioprocessing. Taken together, this work highlights ADP1 as an ideal host for a variety of sustainability and synthetic biology applications.

0961 Comparison of Clinical Characteristics of Children With Narcolepsy With and Without Sleep Related Movement Disorders

Introduction

Narcolepsy is known to be associated with sleep related movement disorders (SRMD) including periodic limb movement and restless leg syndrome. However, there is paucity of data comparing the clinical characteristics of children with narcolepsy with and without SRMD.

Methods

Retrospective chart review of all children presenting to the sleep clinic for sleep problems between March 2016 to June 2017 was performed. Demographics, sleep intake patient questionnaires and ICD-10 codes for comorbidities and sleep diagnoses were collected. Children with diagnosis of narcolepsy (ICD-10 G47.4) were included in this study. Cohort was divided into 2 groups- with and without co-existing diagnoses of sleep related movement disorders (ICD-10 G47.6). Demographics, presenting symptoms, Epworth sleepiness scores and prevalence of sleep comorbidities were compared using T-test (continuous) and Chi square (categorical). Unadjusted odds ratio was calculated for demographics and presence of SRMD. P value of <0.05 was considered significant.

Results

28 (F=14,50%) children with narcolepsy were included. 25% children were diagnosed with SRMD. Mean (SD) age of children with SRMD presenting to the sleep clinic was 11.14 (5.08) years while mean age (SD) of children without SRMD was 9.52 (3.87) years. Age and race of children with and without SRMD were not statistically different. There was an increased prevalence of females in the group with narcolepsy and SRMD compared to the group without SRMD (86%vs38%, p=0.029). Epworth sleepiness score was not statistically different between the 2 groups. Female gender increased the odds of SRMD in children with narcolepsy (OR:9.75, 0.98- 96.56).

Conclusion

Children with narcolepsy can present with comorbid sleep related movement disorder. Females were more likely to present with associated SRMD compared to males.

Support

None

Genomes of ubiquitous marine and hypersaline Hydrogenovibrio, Thiomicrorhabdus and Thiomicrospira spp. encode a diversity of mechanisms to sustain chemolithoautotrophy in heterogeneous environments

Chemolithoautotrophic bacteria from the genera Hydrogenovibrio, Thiomicrorhabdus and Thiomicrospira are common, sometimes dominant, isolates from sulfidic habitats including hydrothermal vents, soda and salt lakes and marine sediments. Their genome sequences confirm their membership in a deeply branching clade of the Gammaproteobacteria. Several adaptations to heterogeneous habitats are apparent. Their genomes include large numbers of genes for sensing and responding to their environment (EAL- and GGDEF-domain proteins and methyl-accepting chemotaxis proteins) despite their small sizes (2.1-3.1 Mbp). An array of sulfur-oxidizing complexes are encoded, likely to facilitate these organisms' use of multiple forms of reduced sulfur as electron donors. Hydrogenase genes are present in some taxa, including group 1d and 2b hydrogenases in Hydrogenovibrio marinus and H. thermophilus MA2-6, acquired via horizontal gene transfer. In addition to high-affinity cbb₃ cytochrome c oxidase, some also encode cytochrome bd-type quinol oxidase or ba₃ -type cytochrome c oxidase, which could facilitate growth under different oxygen tensions, or maintain redox balance. Carboxysome operons are present in most, with genes downstream encoding transporters from four evolutionarily distinct families, which may act with the carboxysomes to form CO₂ concentrating mechanisms. These adaptations to habitat variability likely contribute to the cosmopolitan distribution of these organisms.

Cultured muscle cells from insulin-resistant type 2 diabetes patients have impaired insulin, but normal 5-amino-4-imidazolecarboxamide riboside-stimulated, glucose uptake

Impaired insulin action is a characteristic feature of type 2 diabetes. The study aims were to investigate whether after prolonged culture skeletal muscle cultures from insulin-resistant, type 2 diabetic patients (taking >100 U insulin/d) displayed impaired insulin signaling effects compared with cultures from nondiabetic controls and to determine whether retained abnormalities were limited to insulin action by studying an alternative pathway of stimulated glucose uptake. Studies were performed on myotubes differentiated for 7 d between passages 4 and 6. Insulin-stimulated glucose uptake (100 nm; P < 0.05) and insulin-stimulated glycogen synthesis (1 nm; P < 0.01) were significantly impaired in the diabetic vs. control cultures. Protein kinase B (PKB) expression and phosphorylated PKB levels in response to insulin stimulation (20 nm) were comparable in the diabetic and control cultures. 5-Amino-4-imidazolecarboxamide riboside (AICAR) mimics the effect of exercise on glucose uptake by activating AMP-activated protein kinase. There was no difference in AICAR (2 mm)-stimulated glucose uptake between diabetic vs. control myotube cultures (P = not significant). In conclusion, diabetic muscle cultures retain signaling defects after prolonged culture that appear specific to the insulin signaling pathway, but not involving PKB. This supports an intrinsic abnormality of the diabetic muscle cells that is most likely to have a genetic basis.

Genetics of type 2 diabetes and insulin resistance: knowledge from human studies

Both type 2 diabetes mellitus (T2DM) and insulin resistance are complex traits in which multiple gene effects and metabolic and environmental factors combine to contribute to the overall pathogenesis of these conditions. This complexity has complicated the search for susceptibility genes and has led to different but complementary approaches being used for the detection of gene effects. These include the study of monogenic cases of insulin resistance and T2DM, association studies of candidate genes and genome-wide scans. The peroxisome proliferator-activated receptor gamma (PPARgamma) and calpain-10 (CAPN10) genes have recently been identified as T2DM susceptibility genes, and the lessons learnt from these studies are helping to shape future strategies to search for additional susceptibility genes in T2DM and insulin resistance.

Serum S-100beta protein is a potential biochemical marker for cerebral oedema complicating severe diabetic ketoacidosis

CASE REPORT

A 39-year-old man with Type 1 diabetes mellitus was hospitalized with severe diabetic ketoacidosis (DKA). Sixteen hours after admission he suddenly deteriorated having a respiratory then cardiac arrest. A brain computed tomography scan performed 2 h after the respiratory arrest showed severe cerebral oedema. Serial serum samples were stored and analysed for S-100beta protein. The S-100beta protein concentration was initially normal (0.12 microg/l) then rose significantly before the onset of the respiratory arrest (8.5 h = 0.61 microg/l, 14.5 h = 0.9 microg/l, 18 h = 1.6 microg/l, 25.5 h = 3.1 microg/l, 34 h = 4.6 microg/l and44 h = 19.5 microg/l).

CONCLUSIONS

In this case of DKA, serum S-100beta concentration rose coinciding with the onset of cerebral oedema, before it became clinically evident. Monitoring serum S-100beta may have a useful role in the management of DKA.