Publications by authors named "Christopher Jenkins"

102 Publications

Generation of Distinct Differentially Culturable Forms of following Starvation at Low Temperature.

Microbiol Spectr 2022 Jan 5:e0211021. Epub 2022 Jan 5.

Department of Respiratory Sciences, University of Leicestergrid.9918.9, Leicester, United Kingdom.

Bacteria have developed unique mechanisms to adapt to environmental stresses and challenges of the immune system. Here, we report that Burkholderia pseudomallei, the causative agent of melioidosis, and its laboratory surrogate, Burkholderia thailandensis, utilize distinct mechanisms for surviving starvation at different incubation temperatures. At 21°C, are present as short rods which can rapidly reactivate and form colonies on solid media. At 4°C, convert into coccoid forms that cannot be cultured on solid agar but can be resuscitated in liquid media supplemented with supernatant obtained from logarithmic phase cultures of B. thailandensis, or catalase and Tween 80, thus displaying characteristics of differentially culturable bacteria (DCB). These DCB have low intensity fluorescence when stained with SYTO 9, have an intact cell membrane (propidium iodide negative), and contain 16S rRNA at levels comparable with growing cells. We also present evidence that lytic transglycosylases, a family of peptidoglycan-remodeling enzymes, are involved in the generation of coccoid forms and their resuscitation to actively growing cells. A B. pseudomallei Δ mutant with four genes deleted did not produce coccoid forms at 4°C and could not be resuscitated in the liquid media evaluated. Our findings provide insights into the adaptation of to nutrient limitation and the generation of differentially culturable bacteria. Bacterial pathogens exhibit physiologically distinct forms that enable their survival in an infected host, the environment and following exposure to antimicrobial agents. B. pseudomallei causes the disease melioidosis, which has a high mortality rate and is difficult to treat with antibiotics. The bacterium is endemic to several countries and detected in high abundance in the environment. Here, we report that during starvation at low temperature, B. pseudomallei produces coccoid forms that cannot grow in standard media and which, therefore, can be challenging to detect using common tools. We provide evidence that the formation of these cocci is mediated by cell wall-specialized enzymes and lytic transglycosylases, and that resuscitation of these forms occurs following the addition of catalase and Tween 80. Our findings have important implications for the disease control and detection of B. pseudomallei, an agent of both public health and defense interest.
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http://dx.doi.org/10.1128/spectrum.02110-21DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8729786PMC
January 2022

Accounting for geographic variation in species-habitat associations during habitat suitability modeling.

Ecol Appl 2021 Dec 6:e2504. Epub 2021 Dec 6.

The Orianne Society, 11 Old Fruitstand Lane, Tiger, GA, USA.

Range-wide species conservation efforts are facilitated by spatially explicit estimates of habitat suitability. However, species-environment relationships often vary geographically and models assuming geographically constant relationships may result in misleading inferences. We present the first range-wide habitat suitability model for the federally threatened eastern indigo snake (Drymarchon couperi) as a case study illustrating an approach to account for known latitudinal variation in habitat associations. Specifically, we modeled habitat suitability using interactive relationships between minimum winter temperature and several a priori environmental covariates and compared our results to those from models assuming geographically constant relationships. We found that multi-scale models including interactive effects with winter temperature outperformed single-scale models and models not including interactive effects with winter temperature. Our top-ranked model had suitable range-wide predictive performance and identified numerous large (i.e., ≥ 1,000 ha) potential habitat patches throughout the indigo snake range. Predictive performance was greatest in southern Georgia and northern Florida likely reflecting more restrictive indigo snake habitat associations in these regions. This study illustrates how modeling interactive effects between temperature and environmental covariates can improve the performance of habitat suitability models across geographically varying environmental gradients.
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http://dx.doi.org/10.1002/eap.2504DOI Listing
December 2021

The Effect of Clozapine on Self-reported Duration of Sleep and Its Interaction With 23 Other Medications: A 5-Year Naturalistic Study.

J Clin Psychopharmacol 2021 Sep-Oct 01;41(5):534-539

From the Cambridgeshire and Peterborough NHS Foundation Trust.

Background: Sedation is a common and incapacitating clozapine adverse effect, but the factors associated with sedation and its pharmacological management remain poorly studied.

Methods: We conducted a retrospective cohort study based on deidentified electronic clinical records of clozapine-treated patients from the secondary mental health care provider for Cambridgeshire and Peterborough, United Kingdom. We first evaluated cross-sectionally the influence of clozapine dose, clozapine, and norclozapine plasma levels on self-reported hours slept, as a proxy for sedation, using bivariate correlation and then the longitudinal effect of changes in clozapine dose and other 23 medications using linear mixed effect models. We followed 241 clozapine-treated patients for 56 months on average, with 2237 face-to-face assessments in total.

Results: Patients slept for a mean of 9.35 h/d, with 46% reporting 10 h/d or more. Cross-sectionally, sleep duration did not correlate with clozapine dose (r = 0.14, P = 0.106), but with clozapine plasma levels (r = 0.38, P < 0.0001) and norclozapine plasma levels (r = 0.25, P = 0.005). Longitudinally, the final mixed-effects model revealed 4 pharmacological variables that had a significant impact on hours slept: clozapine, risperidone augmentation, and atenolol were associated with increased sleep, whereas aripiprazole augmentation was associated with decreased sleep. We found that 20 other psychotropic medications measured were not associated with changes in sleep when added to clozapine. Excess sleep is a clozapine level-dependent adverse effect.

Conclusions: The impact of different augmentation strategies might help clinicians decide on the most adequate strategy, albeit further studies should confirm our results.
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http://dx.doi.org/10.1097/JCP.0000000000001432DOI Listing
December 2021

Structural Heart Interventions During COVID-19.

Curr Probl Cardiol 2022 Feb 24;47(2):100934. Epub 2021 Jul 24.

Department of Cardiology, Ochsner Medical Center, New Orleans, LA; Department of Cardiology, Albert Einstein University, Montefiore Medical Center, Bronx, NY.

The spread of Coronavirus Disease 2019 (COVID-19) pandemic across the globe and the United States presented unprecedented challenges with dawn of new policies to reserve resources and protect the public. One of the major policies adopted by hospitals across the nations were postponement of non-emergent procedures such as transaortic valve replacement (TAVR), left atrial appendage closure device (LAAC), MitraClip and CardioMEMS. Guidelines were based mainly on the avoidable clinical outcomes occurring during COVID-19 era. As our understanding of the SARS-CoV-2 evolved, advanced cardiac procedures may safely continue through careful advanced coordination. We aim to highlight the new guidelines published by different major cardiovascular societies, and discuss solutions to safely perform procedures to improve outcomes in a patient population with high acuity of illness during the COVID-19 pandemic era.
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http://dx.doi.org/10.1016/j.cpcardiol.2021.100934DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8302827PMC
February 2022

Frequency drift in MR spectroscopy at 3T.

Neuroimage 2021 11 24;241:118430. Epub 2021 Jul 24.

School of Health Sciences, Purdue University, West Lafayette, IN USA.

Purpose: Heating of gradient coils and passive shim components is a common cause of instability in the B field, especially when gradient intensive sequences are used. The aim of the study was to set a benchmark for typical drift encountered during MR spectroscopy (MRS) to assess the need for real-time field-frequency locking on MRI scanners by comparing field drift data from a large number of sites.

Method: A standardized protocol was developed for 80 participating sites using 99 3T MR scanners from 3 major vendors. Phantom water signals were acquired before and after an EPI sequence. The protocol consisted of: minimal preparatory imaging; a short pre-fMRI PRESS; a ten-minute fMRI acquisition; and a long post-fMRI PRESS acquisition. Both pre- and post-fMRI PRESS were non-water suppressed. Real-time frequency stabilization/adjustment was switched off when appropriate. Sixty scanners repeated the protocol for a second dataset. In addition, a three-hour post-fMRI MRS acquisition was performed at one site to observe change of gradient temperature and drift rate. Spectral analysis was performed using MATLAB. Frequency drift in pre-fMRI PRESS data were compared with the first 5:20 minutes and the full 30:00 minutes of data after fMRI. Median (interquartile range) drifts were measured and showed in violin plot. Paired t-tests were performed to compare frequency drift pre- and post-fMRI. A simulated in vivo spectrum was generated using FID-A to visualize the effect of the observed frequency drifts. The simulated spectrum was convolved with the frequency trace for the most extreme cases. Impacts of frequency drifts on NAA and GABA were also simulated as a function of linear drift. Data from the repeated protocol were compared with the corresponding first dataset using Pearson's and intraclass correlation coefficients (ICC).

Results: Of the data collected from 99 scanners, 4 were excluded due to various reasons. Thus, data from 95 scanners were ultimately analyzed. For the first 5:20 min (64 transients), median (interquartile range) drift was 0.44 (1.29) Hz before fMRI and 0.83 (1.29) Hz after. This increased to 3.15 (4.02) Hz for the full 30 min (360 transients) run. Average drift rates were 0.29 Hz/min before fMRI and 0.43 Hz/min after. Paired t-tests indicated that drift increased after fMRI, as expected (p < 0.05). Simulated spectra convolved with the frequency drift showed that the intensity of the NAA singlet was reduced by up to 26%, 44 % and 18% for GE, Philips and Siemens scanners after fMRI, respectively. ICCs indicated good agreement between datasets acquired on separate days. The single site long acquisition showed drift rate was reduced to 0.03 Hz/min approximately three hours after fMRI.

Discussion: This study analyzed frequency drift data from 95 3T MRI scanners. Median levels of drift were relatively low (5-min average under 1 Hz), but the most extreme cases suffered from higher levels of drift. The extent of drift varied across scanners which both linear and nonlinear drifts were observed.
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http://dx.doi.org/10.1016/j.neuroimage.2021.118430DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8456751PMC
November 2021

Improving the resolution of canine genome-wide association studies using genotype imputation: A study of two breeds.

Anim Genet 2021 Oct 12;52(5):703-713. Epub 2021 Jul 12.

Department of Veterinary Medicine, Kennel Club Genetics Centre1, University of Cambridge, Cambridge, UK.

Genotype imputation using a reference panel that combines high-density array data and publicly available whole genome sequence consortium variant data is potentially a cost-effective method to increase the density of extant lower-density array datasets. In this study, three datasets (two Border Collie; one Italian Spinone) generated using a legacy array (Illumina CanineHD, 173 662 SNPs) were utilised to assess the feasibility and accuracy of this approach and to gather additional evidence for the efficacy of canine genotype imputation. The cosmopolitan reference panels used to impute genotypes comprised dogs of 158 breeds, mixed breed dogs, wolves and Chinese indigenous dogs, as well as breed-specific individuals genotyped using the Axiom Canine HD array. The two Border Collie reference panels comprised 808 individuals including 79 Border Collies and 426 326 or 426 332 SNPs; and the Italian Spinone reference panel comprised 807 individuals including 38 Italian Spinoni and 476 313 SNPs. A high accuracy for imputation was observed, with the lowest accuracy observed for one of the Border Collie datasets (mean R  = 0.94) and the highest for the Italian Spinone dataset (mean R  = 0.97). This study's findings demonstrate that imputation of a legacy array study set using a reference panel comprising both breed-specific array data and multi-breed variant data derived from whole genomes is effective and accurate. The process of canine genotype imputation, using the valuable growing resource of publicly available canine genome variant datasets alongside breed-specific data, is described in detail to facilitate and encourage use of this technique in canine genetics.
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http://dx.doi.org/10.1111/age.13117DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8514152PMC
October 2021

Multiscale assessment of functional connectivity: Landscape genetics of eastern indigo snakes in an anthropogenically fragmented landscape in central Florida.

Mol Ecol 2021 07 2;30(14):3422-3438. Epub 2021 Jun 2.

Department of Environmental Conservation, University of Massachusetts, Amherst, MA, USA.

Landscape features can strongly influence gene flow and the strength and direction of these effects may vary across spatial scales. However, few studies have evaluated methodological approaches for selecting spatial scales in landscape genetics analyses, in part because of computational challenges associated with optimizing landscape resistance surfaces (LRS). We used the federally threatened eastern indigo snake (Drymarchon couperi) in central Florida as a case study with which to compare the importance of landscape features and their scales of effect in influencing gene flow. We used genetic algorithms (ResistanceGA) to empirically optimize LRS using categorical land cover surfaces, multiscale resource selection surfaces (RSS), and four combinations of landscape covariates measured at multiple spatial scales (multisurface multiscale LRS). We compared LRS where scale was selected using pseudo- and full optimization. Multisurface multiscale LRS received more empirical support than LRS optimized from categorical land cover surfaces or RSS. Multiscale LRS with scale selected using full optimization generally outperformed those with scale selected using pseudo-optimization. Multiscale LRS with large spatial scales (1200-1800 m) received the most empirical support. Our results highlight the importance of considering landscape features across multiple spatial scales in landscape genetic analyses, particularly broad scales relative to species movement potential. Different effects of scale on home range-level movements and dispersal could explain weak associations between habitat suitability and gene flow in other studies. Our results also demonstrate the importance of large tracts of undeveloped upland habitat with heterogenous vegetation communities and low urbanization for promoting indigo snake connectivity.
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http://dx.doi.org/10.1111/mec.15979DOI Listing
July 2021

Renal interventions in the management of hypertension.

Curr Opin Cardiol 2021 07;36(4):444-452

John Ochsner Heart and Vascular Institute, Ochsner Medical Center, New Orleans, Louisiana.

Purpose Of Review: In the present comprehensive review, we describe the pathophysiology, indications, and evidence for both renal artery stenting and renal artery denervation. We also discuss the procedural techniques, risks, benefits, and future directions of renal intervention in the management of hypertension (HTN).

Recent Findings: Hemodynamic confirmation of lesion severity in severe renal artery stenosis is a resting or hyperemic translesional systolic gradient >20, resting or hyperemic mean translesional gradient >10 and/or renal fractional flow reserve <0.8 are considered severe. Knowing that correct stent size was used is the best predictor of restenosis, intravascular ultrasound is effective and well tolerated for stent sizing. The main categories of renal denervation: radiofrequency ablation, ultrasound, chemical ablation, and brachytherapy have shown impressive outcomes in treating resistant HTN.

Summary: Over the past decade, several studies have shown the safety and benefit of catheter-based renal interventions in managing HTN. Renal artery stenting and renal artery denervation are the leading alternative invasive treatment employed in managing HTN.
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http://dx.doi.org/10.1097/HCO.0000000000000859DOI Listing
July 2021

The Rustenburg Layered Suite formed as a stack of mush with transient magma chambers.

Nat Commun 2021 Jan 21;12(1):505. Epub 2021 Jan 21.

Department of Earth Sciences, Carleton University, 2115 Herzberg Laboratories, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada.

The Rustenburg Layered Suite of the Bushveld Complex of South Africa is a vast layered accumulation of mafic and ultramafic rocks. It has long been regarded as a textbook result of fractional crystallization from a melt-dominated magma chamber. Here, we show that most units of the Rustenburg Layered Suite can be derived with thermodynamic models of crustal assimilation by komatiitic magma to form magmatic mushes without requiring the existence of a magma chamber. Ultramafic and mafic cumulate layers below the Upper and Upper Main Zone represent multiple crystal slurries produced by assimilation-batch crystallization in the upper and middle crust, whereas the chilled marginal rocks represent complementary supernatant liquids. Only the uppermost third formed via lower-crustal assimilation-fractional crystallization and evolved by fractional crystallization within a melt-rich pocket. Layered intrusions need not form in open magma chambers. Mineral deposits hitherto attributed to magma chamber processes might form in smaller intrusions of any geometric form, from mushy systems entirely lacking melt-dominated magma chambers.
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http://dx.doi.org/10.1038/s41467-020-20778-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7820422PMC
January 2021

Complete heart block as a herald sign for cardiac lymphoma.

BMJ Case Rep 2021 Jan 11;14(1). Epub 2021 Jan 11.

Cardiology, Royal Gwent Hospital, Newport, South Wales, UK.

A previously well 48-year-old man presented with presyncope and was found to be in complete heart block. Blood tests, echocardiography and coronary angiography were reported as normal, and a dual chamber permanent pacemaker was inserted. Six months later he re-presented with breathlessness. His chest X-ray showed cardiomegaly and echocardiography revealed a 4.4 cm pericardial effusion. A CT thorax revealed a mass originating from the intra-atrial septum, extending into the right atrium and ventricle. There were multiple pulmonary lesions suspected to be metastases. Histology demonstrated high-grade B-cell lymphoma. He was treated with eight cycles of R-CHOP chemotherapy and showed good radiological and clinical improvement. Post-treatment echocardiography found severe left ventricular dysfunction with an ejection fraction of <20%. Heart failure medical therapy was optimised and the pacemaker was upgraded to a resynchronisation device. A repeat scan 6 months post device upgrade showed an improvement in ejection fraction to 45%-50%.
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http://dx.doi.org/10.1136/bcr-2020-239356DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7802647PMC
January 2021

Rotatory subluxation of the proximal interphalangeal joint: an easily missed diagnosis.

BMJ Case Rep 2021 Jan 11;14(1). Epub 2021 Jan 11.

Trauma and Orthopaedics, Bristol Royal Infirmary, Bristol, UK.

We present a case of volar rotatory subluxation of index finger proximal interphalangeal joint (PIPJ) following a skiing accident. The injury was initially perceived to be a central slip rupture and treatment was directed as such. After the initial delay in the diagnosis, the patient underwent surgery during which his radial collateral ligament was found to be avulsed from the proximal origin, the radial lateral band palmarly subluxed and was interposed in the joint space. This structure was also adhered to the uninjured volar plate.PIPJ volar rotatory subluxation could be readily missed in the acute setting. Without surgery, the functional outcome could be mediocre and to the patient's detriment.
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http://dx.doi.org/10.1136/bcr-2020-237402DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7802693PMC
January 2021

Percutaneous corrective osteotomy for rotational malunion of metacarpal and phalangeal fractures.

J Hand Surg Eur Vol 2021 May 29;46(4):420-422. Epub 2020 Sep 29.

Department of Orthopaedic Surgery, Royal United Hospital, Bath, UK.

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http://dx.doi.org/10.1177/1753193420960315DOI Listing
May 2021

A functional role for eicosanoid-lysophospholipids in activating monocyte signaling.

J Biol Chem 2020 08 8;295(34):12167-12180. Epub 2020 Jul 8.

Department of Chemistry, Washington University, Saint Louis, Missouri, USA; Division of Bioorganic Chemistry and Molecular Pharmacology, Department of Medicine, Washington University School of Medicine, Saint Louis, Missouri, USA; Developmental Biology, Washington University School of Medicine, Saint Louis, Missouri, USA; Center for Cardiovascular Research, Department of Medicine, Washington University School of Medicine, Saint Louis, Missouri, USA. Electronic address:

Recently, eicosanoid-lysophospholipids were identified as novel metabolites generated from the direct cyclooxygenase- or lipoxygenase-catalyzed oxidation of 2-arachidonoyl-lysophospholipids produced from either phospholipase A-mediated hydrolysis of diacyl arachidonoyl-phospholipids or through the cytochrome -catalyzed oxidative hydrolysis of the vinyl ether linkage of arachidonoyl-plasmalogens. Although the metabolic pathways generating eicosanoid-lysophospholipids have been increasingly appreciated, the signaling functions of eicosanoid-lysophospholipids remain largely unknown. Herein, we demonstrate that 2-12()-HETE-lysophospholipids as well as nonesterified 12()-HETE are potent lipid mediators that activate THP-1 human monocytic cells to generate tumor necrosis factor α (TNFα) and interleukin 8 (IL8). Remarkably, low nanomolar concentrations of 12()-HETE-lysophospholipids, but not other oxidized signaling lipids examined activated THP-1 cells resulting in the production of large amounts of TNFα. Moreover, TNFα release induced by 12()-HETE-lysophospholipids was inhibited by the TNFα converting enzyme inhibitor TAPI-0 indicating normal processing of TNFα in THP-1 cells stimulated with these agonists. Western blotting analyses revealed that 12()-HETE-lysophospholipids activated the phosphorylation of NFκB p65, suggesting activation of the canonical NFκB signaling pathway. Importantly, activation of THP-1 cells to release TNFα was stereoselective with 12()-HETE favored over 12()-HETE. Furthermore, the EC of 2-12()-HETE-lysophosphatidylcholine in activating THP-1 cells was 2.1 nm, whereas the EC of free 12()-HETE was 23 nm Additionally, lipid extracts of activated platelets were separated by RP-HPLC demonstrating the coelution of 12()-HETE with fractions initiating TNFα release. Collectively, these results demonstrate the potent signaling properties of 2-12()-HETE-lysophospholipids and 12()-HETE by their ability to release TNFα and activate NFκB signaling thereby revealing a previously unknown role of 2-12()-HETE-lysophospholipids in mediating inflammatory responses.
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http://dx.doi.org/10.1074/jbc.RA120.013619DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7443508PMC
August 2020

A functional role for eicosanoid-lysophospholipids in activating monocyte signaling.

J Biol Chem 2020 08 8;295(34):12167-12180. Epub 2020 Jul 8.

Department of Chemistry, Washington University, Saint Louis, Missouri, USA; Division of Bioorganic Chemistry and Molecular Pharmacology, Department of Medicine, Washington University School of Medicine, Saint Louis, Missouri, USA; Developmental Biology, Washington University School of Medicine, Saint Louis, Missouri, USA; Center for Cardiovascular Research, Department of Medicine, Washington University School of Medicine, Saint Louis, Missouri, USA. Electronic address:

Recently, eicosanoid-lysophospholipids were identified as novel metabolites generated from the direct cyclooxygenase- or lipoxygenase-catalyzed oxidation of 2-arachidonoyl-lysophospholipids produced from either phospholipase A-mediated hydrolysis of diacyl arachidonoyl-phospholipids or through the cytochrome -catalyzed oxidative hydrolysis of the vinyl ether linkage of arachidonoyl-plasmalogens. Although the metabolic pathways generating eicosanoid-lysophospholipids have been increasingly appreciated, the signaling functions of eicosanoid-lysophospholipids remain largely unknown. Herein, we demonstrate that 2-12()-HETE-lysophospholipids as well as nonesterified 12()-HETE are potent lipid mediators that activate THP-1 human monocytic cells to generate tumor necrosis factor α (TNFα) and interleukin 8 (IL8). Remarkably, low nanomolar concentrations of 12()-HETE-lysophospholipids, but not other oxidized signaling lipids examined activated THP-1 cells resulting in the production of large amounts of TNFα. Moreover, TNFα release induced by 12()-HETE-lysophospholipids was inhibited by the TNFα converting enzyme inhibitor TAPI-0 indicating normal processing of TNFα in THP-1 cells stimulated with these agonists. Western blotting analyses revealed that 12()-HETE-lysophospholipids activated the phosphorylation of NFκB p65, suggesting activation of the canonical NFκB signaling pathway. Importantly, activation of THP-1 cells to release TNFα was stereoselective with 12()-HETE favored over 12()-HETE. Furthermore, the EC of 2-12()-HETE-lysophosphatidylcholine in activating THP-1 cells was 2.1 nm, whereas the EC of free 12()-HETE was 23 nm Additionally, lipid extracts of activated platelets were separated by RP-HPLC demonstrating the coelution of 12()-HETE with fractions initiating TNFα release. Collectively, these results demonstrate the potent signaling properties of 2-12()-HETE-lysophospholipids and 12()-HETE by their ability to release TNFα and activate NFκB signaling thereby revealing a previously unknown role of 2-12()-HETE-lysophospholipids in mediating inflammatory responses.
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http://dx.doi.org/10.1074/jbc.RA120.013619DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7443508PMC
August 2020

12-LOX catalyzes the oxidation of 2-arachidonoyl-lysolipids in platelets generating eicosanoid-lysolipids that are attenuated by iPLAγ knockout.

J Biol Chem 2020 04 11;295(16):5307-5320. Epub 2020 Mar 11.

Division of Bioorganic Chemistry and Molecular Pharmacology, Department of Medicine, Washington University School of Medicine, Saint Louis, Missouri 63110; Department of Developmental Biology, Washington University School of Medicine, Saint Louis, Missouri 63110; Department of Chemistry, Washington University, Saint Louis, Missouri 63130. Electronic address:

The canonical pathway of eicosanoid production in most mammalian cells is initiated by phospholipase A-mediated release of arachidonic acid, followed by its enzymatic oxidation resulting in a vast array of eicosanoid products. However, recent work has demonstrated that the major phospholipase in mitochondria, iPLAγ (patatin-like phospholipase domain containing 8 (PNPLA8)), possesses -1 specificity, with polyunsaturated fatty acids at the -2 position generating polyunsaturated -2-acyl lysophospholipids. Through strategic chemical derivatization, chiral chromatographic separation, and multistage tandem MS, here we first demonstrate that human platelet-type 12-lipoxygenase (12-LOX) can directly catalyze the regioselective and stereospecific oxidation of 2-arachidonoyl-lysophosphatidylcholine (2-AA-LPC) and 2-arachidonoyl-lysophosphatidylethanolamine (2-AA-LPE). Next, we identified these two eicosanoid-lysophospholipids in murine myocardium and in isolated platelets. Moreover, we observed robust increases in 2-AA-LPC, 2-AA-LPE, and their downstream 12-LOX oxidation products, 12()-HETE-LPC and 12()-HETE-LPE, in calcium ionophore (A23187)-stimulated murine platelets. Mechanistically, genetic ablation of iPLAγ markedly decreased the calcium-stimulated production of 2-AA-LPC, 2-AA-LPE, and 12-HETE-lysophospholipids in mouse platelets. Importantly, a potent and selective 12-LOX inhibitor, ML355, significantly inhibited the production of 12-HETE-LPC and 12-HETE-LPE in activated platelets. Furthermore, we found that aging is accompanied by significant changes in 12-HETE-LPC in murine serum that were also markedly attenuated by iPLAγ genetic ablation. Collectively, these results identify previously unknown iPLAγ-initiated signaling pathways mediated by direct 12-LOX oxidation of 2-AA-LPC and 2-AA-LPE. This oxidation generates previously unrecognized eicosanoid-lysophospholipids that may serve as biomarkers for age-related diseases and could potentially be used as targets in therapeutic interventions.
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http://dx.doi.org/10.1074/jbc.RA119.012296DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7170522PMC
April 2020

Characterisation of canine KCNIP4: A novel gene for cerebellar ataxia identified by whole-genome sequencing two affected Norwegian Buhund dogs.

PLoS Genet 2020 01 30;16(1):e1008527. Epub 2020 Jan 30.

Kennel Club Genetics Centre, Animal Health Trust, Newmarket, Suffolk, United Kingdom.

A form of hereditary cerebellar ataxia has recently been described in the Norwegian Buhund dog breed. This study aimed to identify the genetic cause of the disease. Whole-genome sequencing of two Norwegian Buhund siblings diagnosed with progressive cerebellar ataxia was carried out, and sequences compared with 405 whole genome sequences of dogs of other breeds to filter benign common variants. Nine variants predicted to be deleterious segregated among the genomes in concordance with an autosomal recessive mode of inheritance, only one of which segregated within the breed when genotyped in additional Norwegian Buhunds. In total this variant was assessed in 802 whole genome sequences, and genotyped in an additional 505 unaffected dogs (including 146 Buhunds), and only four affected Norwegian Buhunds were homozygous for the variant. The variant identified, a T to C single nucleotide polymorphism (SNP) (NC_006585.3:g.88890674T>C), is predicted to cause a tryptophan to arginine substitution in a highly conserved region of the potassium voltage-gated channel interacting protein KCNIP4. This gene has not been implicated previously in hereditary ataxia in any species. Evaluation of KCNIP4 protein expression through western blot and immunohistochemical analysis using cerebellum tissue of affected and control dogs demonstrated that the mutation causes a dramatic reduction of KCNIP4 protein expression. The expression of alternative KCNIP4 transcripts within the canine cerebellum, and regional differences in KCNIP4 protein expression, were characterised through RT-PCR and immunohistochemistry respectively. The voltage-gated potassium channel protein KCND3 has previously been implicated in spinocerebellar ataxia, and our findings suggest that the Kv4 channel complex KCNIP accessory subunits also have an essential role in voltage-gated potassium channel function in the cerebellum and should be investigated as potential candidate genes for cerebellar ataxia in future studies in other species.
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http://dx.doi.org/10.1371/journal.pgen.1008527DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7012447PMC
January 2020

Genetic study of border terriers.

Vet Rec 2019 10;185(13):411

Animal Health Trust, Lanwades Park, Kentford, Newmarket, Suffolk CB8 7UU.

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http://dx.doi.org/10.1136/vr.l5798DOI Listing
October 2019

The lytic transglycosylase, LtgG, controls cell morphology and virulence in Burkholderia pseudomallei.

Sci Rep 2019 07 30;9(1):11060. Epub 2019 Jul 30.

Department of Infection, Immunity and Inflammation, University of Leicester, Leicester, UK.

Burkholderia pseudomallei is the causative agent of the tropical disease melioidosis. Its genome encodes an arsenal of virulence factors that allow it, when required, to switch from a soil dwelling bacterium to a deadly intracellular pathogen. With a high intrinsic resistance to antibiotics and the ability to overcome challenges from the host immune system, there is an increasing requirement for new antibiotics and a greater understanding into the molecular mechanisms of B. pseudomallei virulence and dormancy. The peptidoglycan remodeling enzymes, lytic transglycosylases (Ltgs) are potential targets for such new antibiotics. Ltgs cleave the glycosidic bonds within bacterial peptidoglycan allowing for the insertion of peptidoglycan precursors during cell growth and division, and cell membrane spanning structures such as flagella and secretion systems. Using bioinformatic analysis we have identified 8 putative Ltgs in B. pseudomallei K96243. We aimed to investigate one of these Ltgs, LtgG (BPSL3046) through the generation of deletion mutants and biochemical analysis. We have shown that LtgG is a key contributor to cellular morphology, division, motility and virulence in BALB/c mice. We have determined the crystal structure of LtgG and have identified various amino acids likely to be important in peptidoglycan binding and catalytic activity. Recombinant protein assays and complementation studies using LtgG containing a site directed mutation in aspartate 343, confirmed the essentiality of this amino acid in the function of LtgG.
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http://dx.doi.org/10.1038/s41598-019-47483-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6667503PMC
July 2019

Phenotypic Effects of Retrogenes on Intervertebral Disc Disease in Dogs.

Genes (Basel) 2019 06 7;10(6). Epub 2019 Jun 7.

Department of Population Health and Reproduction, University of California-Davis, Davis, CA 95616, USA.

Two retrogenes on chromosomes 12 (12-RG) and 18 (18-RG) contribute to short-limbed phenotypes in dogs. 12-RG has also been associated with intervertebral disc disease (IVDD). Both of these retrogenes were found to be widespread among dog breeds with allele frequencies ranging from 0.02 to 1; however, their additive contribution to disease is unknown. Surgical cases of IVDD ( = 569) were evaluated for age of onset, disc calcification, and genotypes for the retrogenes. Multivariable linear regression analysis identified the presence of one or two copies of 12-RG associated with significantly younger age at first surgery in a dominant manner. 18-RG had only a minor effect in dogs with one copy. Multivariable logistic regression showed that 12-RG had an additive effect on radiographic disc calcification, while 18-RG had no effect. Multivariable logistic regression using mixed breed cases and controls identified only 12-RG as highly associated with disc herniation in a dominant manner (Odds Ratio, OR, 18.42, 95% Confidence Interval (CI) 7.44 to 50.26; < 0.001). The relative risk for disc surgery associated with 12-RG varied from 5.5 to 15.1 within segregating breeds and mixed breeds. The retrogene on CFA12 acts in a dominant manner to decrease the age of onset and increase the overall risk of disc disease in dogs. Other modifiers of risk may be present within certain breeds, including the retrogene on CFA18.
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http://dx.doi.org/10.3390/genes10060435DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6627552PMC
June 2019

Synthesis of oxidized phospholipids by -1 acyltransferase using 2-15-HETE lysophospholipids.

J Biol Chem 2019 06 12;294(26):10146-10159. Epub 2019 May 12.

From the Department of Chemistry, Washington University, Saint Louis, Missouri 63130 and

Recently, oxidized phospholipid species have emerged as important signaling lipids in activated immune cells and platelets. The canonical pathway for the synthesis of oxidized phospholipids is through the release of arachidonic acid by cytosolic phospholipase Aα (cPLAα) followed by its enzymatic oxidation, activation of the carboxylate anion by acyl-CoA synthetase(s), and re-esterification to the -2 position by -2 acyltransferase activity ( the Lands cycle). However, recent studies have demonstrated the unanticipated significance of -1 hydrolysis of arachidonoyl-containing choline and ethanolamine glycerophospholipids by other phospholipases to generate the corresponding 2-arachidonoyl-lysolipids. Herein, we identified a pathway for oxidized phospholipid synthesis comprising sequential -1 hydrolysis by a phospholipase A ( by patatin-like phospholipase domain-containing 8 (PNPLA8)), direct enzymatic oxidation of the resultant 2-arachidonoyl-lysophospholipids, and the esterification of oxidized 2-arachidonoyl-lysophospholipids by acyl-CoA-dependent -1 acyltransferase(s). To circumvent ambiguities associated with acyl migration or hydrolysis, we developed a synthesis for optically active (d- and l-enantiomers) nonhydrolyzable analogs of 2-arachidonoyl-lysophosphatidylcholine (2-AA-LPC). -1 acyltransferase activity in murine liver microsomes stereospecifically and preferentially utilized the naturally occurring l-enantiomer of the ether analog of lysophosphatidylcholine. Next, we demonstrated the high selectivity of the -1 acyltransferase activity for saturated acyl-CoA species. Importantly, we established that 2-15-hydroxyeicosatetraenoic acid (HETE) ether-LPC -1 esterification is markedly activated by thrombin treatment of murine platelets to generate oxidized PC. Collectively, these findings demonstrate the enantiomeric specificity and saturated acyl-CoA selectivity of microsomal -1 acyltransferase(s) and reveal its participation in a previously uncharacterized pathway for the synthesis of oxidized phospholipids with cell-signaling properties.
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http://dx.doi.org/10.1074/jbc.RA119.008766DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6664186PMC
June 2019

Taxonomic and conservation implications of population genetic admixture, mito-nuclear discordance, and male-biased dispersal of a large endangered snake, Drymarchon couperi.

PLoS One 2019 26;14(3):e0214439. Epub 2019 Mar 26.

Department of Biological Sciences and Auburn University Museum of Natural History, Auburn University, Auburn, Alabama, United States of America.

Accurate species delimitation and description are necessary to guide effective conservation of imperiled species, and this synergy is maximized when multiple data sources are used to delimit species. We illustrate this point by examining Drymarchon couperi (Eastern Indigo Snake), a large, federally-protected species in North America that was recently divided into two species based on gene sequence data from three loci and heuristic morphological assessment. Here, we re-evaluate the two-species hypothesis for D. couperi by evaluating both population genetic and gene sequence data. Our analyses of 14 microsatellite markers revealed 6-8 genetic population clusters with significant admixture, particularly across the contact zone between the two hypothesized species. Phylogenetic analyses of gene sequence data with maximum-likelihood methods suggested discordance between mitochondrial and nuclear markers and provided phylogenetic support for one species rather than two. For these reasons, we place Drymarchon kolpobasileus into synonymy with D. couperi. We suggest inconsistent patterns between mitochondrial and nuclear DNA are driven by high dispersal of males relative to females. We advocate for species delimitation exercises that evaluate admixture and gene flow in addition to phylogenetic analyses, particularly when the latter reveal monophyletic lineages. This is particularly important for taxa, such as squamates, that exhibit strong sex-biased dispersal. Problems associated with over-delimitation of species richness can become particularly acute for threatened and endangered species, because of high costs to conservation when taxonomy demands protection of more individual species than are supported by accumulating data.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0214439PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6435180PMC
December 2019

Hereditary ataxia in four related Norwegian Buhunds.

J Am Vet Med Assoc 2018 Sep;253(6):774-780

CASE DESCRIPTION Two 12-week-old Norwegian Buhunds from a litter of 5 were evaluated because of slowly progressive cerebellar ataxia and fine head tremors. Two other females from the same pedigree had been previously evaluated for similar signs. CLINICAL FINDINGS Findings of general physical examination, CBC, and serum biochemical analysis were unremarkable for all affected puppies. Brain MRI and CSF analysis, including PCR assays for detection of Toxoplasma gondii, Neospora caninum, and canine distemper virus, were performed for 3 dogs, yielding unremarkable results. Urinary organic acid screening, enzyme analysis of fibroblasts cultured from skin biopsy specimens, and brainstem auditory-evoked response testing were performed for 2 puppies, and results were also unremarkable. TREATMENT AND OUTCOME The affected puppies were euthanized at the breeder's request, and their brains and spinal cords were submitted for histologic examination. Histopathologic findings included a markedly reduced expression of calbindin D28K and inositol triphosphate receptor 1 by Purkinje cells, with only mild signs of neuronal degeneration. Results of pedigree analysis suggested an autosomal recessive mode of inheritance. Candidate-gene analysis via mRNA sequencing for 2 of the affected puppies revealed no genetic variants that could be causally associated with the observed abnormalities. CLINICAL RELEVANCE Findings for the dogs of this report suggested the existence of a hereditary form of ataxia in Norwegian Buhunds with histologic characteristics suggestive of Purkinje cell dysfunction. The presence of hereditary ataxia in this breed must be considered both in clinical settings and for breeding strategies.
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http://dx.doi.org/10.2460/javma.253.6.774DOI Listing
September 2018

Advances in assessing reefs for ongoing monitoring.

Ecol Evol 2018 Aug 12;8(15):7673-7687. Epub 2018 Jul 12.

Joint Nature Conservation Committee (JNCC) Peterborough UK.

Standardized and repeatable data acquisition and analyses are required to enable the mapping and condition monitoring of reefs within Marine Protected Areas (MPAs). Changes in habitat condition must be reliably identified and reported to best support evidence-based management. Biogenic reefs in temperate waters, that is, hard matter created by living organisms and raised above the seabed, provide food and shelter for many plant and animal species. This article explores the feasibility of habitat mapping, using remote sensing datasets, as well as metrics for repeatable and suitable assessment of areas of for their status as biogenic reef. Data were gathered within the North Norfolk Sandbanks and Saturn Reef candidate Special Area of Conservation/Site of Community Importance in the southern North Sea. Six study areas were identified as potential locations of biogenic reef using previously acquired data, and these were targeted for further investigation using a combination of high resolution multibeam echosounder and sidescan sonar. Where potential was identified from the acoustic data, a drop-down camera system was employed for visual verification. Areas of known and potential reef were mapped successfully at two of the six study areas, although future approaches should take careful consideration of the seabed morphology and predominant habitat backdrop to successfully interpret such data. Camera tows from reef areas were broken up into 5-s segments, with each segment scored for (a) average tube elevation; (b) average percentage cover; and (c) for the presence or absence of . These metrics were utilized to create summary statistics, including a value of patchiness derived from presence/absence data, that is recommended for application as part of future monitoring programs. The application of this methodology could benefit wider assessments of similar threated or declining habitats such as intertidal beds on mixed and sandy sediments, Maerl beds, beds, beds, and beds where patchiness may also be considered of environmental importance.
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http://dx.doi.org/10.1002/ece3.4292DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6106184PMC
August 2018

Design and characterization of tissue-mimicking gel phantoms for diffusion kurtosis imaging.

Med Phys 2018 Jun 27;45(6):2476-2485. Epub 2018 Apr 27.

Institute of Life Science, Medical School, Swansea University, Swansea, SA2 8PP, UK.

Purpose: The aim of this work was to create tissue-mimicking gel phantoms appropriate for diffusion kurtosis imaging (DKI) for quality assurance, protocol optimization, and sequence development.

Methods: A range of agar, agarose, and polyvinyl alcohol phantoms with concentrations ranging from 1.0% to 3.5%, 0.5% to 3.0%, and 10% to 20%, respectively, and up to 3 g of glass microspheres per 100 ml were created. Diffusion coefficients, excess kurtosis values, and relaxation rates were experimentally determined.

Results: The kurtosis values for the plain gels ranged from 0.05 with 95% confidence interval (CI) of (0.029,0.071) to 0.216(0.185,0.246), well below the kurtosis values reported in the literature for various tissues. The addition of glass microspheres increased the kurtosis of the gels with values up to 0.523(0.465,0.581) observed for gels with the highest concentration of microspheres. Repeat scans of some of the gels after more than 6 months of storage at room temperature indicate changes in the diffusion parameters of less than 10%. The addition of the glass microspheres reduces the apparent diffusion coefficients (ADCs) and increases the longitudinal and transverse relaxation rates, but the values remain comparable to those for plain gels and tissue, with ADCs observed ranging from 818(585,1053) × 10  mm /s to 2257(2118,2296) × 10  mm /s, R values ranging from 0.34(0.32,0.35) 1/s to 0.51(0.50,0.52) 1/s, and R values ranging from 9.69(9.34,10.04) 1/s to 33.07(27.10, 39.04) 1/s.

Conclusions: Glass microspheres can be used to effectively modify diffusion properties of gel phantoms and achieve a range of kurtosis values comparable to those reported for a variety of tissues.
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http://dx.doi.org/10.1002/mp.12907DOI Listing
June 2018

Cytochrome is an oxidative stress-activated plasmalogenase that cleaves plasmenylcholine and plasmenylethanolamine at the -1 vinyl ether linkage.

J Biol Chem 2018 06 12;293(22):8693-8709. Epub 2018 Mar 12.

From the Division of Bioorganic Chemistry and Molecular Pharmacology and

Plasmalogens are phospholipids critical for cell function and signaling that contain a vinyl ether linkage at the -1 position and are highly enriched in arachidonic acid (AA) at the -2 position. However, the enzyme(s) responsible for the cleavage of the vinyl ether linkage in plasmalogens has remained elusive. Herein, we report that cytochrome , in the presence of either cardiolipin (CL), O and HO, or oxidized CL and O, catalyzes the oxidation of the plasmalogen vinyl ether linkage, promoting its hydrolytic cleavage and resultant production of 2-AA-lysolipids and highly reactive α-hydroxy fatty aldehydes. Using stable isotope labeling in synergy with strategic chemical derivatizations and high-mass-accuracy MS, we deduced the chemical mechanism underlying this long sought-after reaction. Specifically, labeling with either O or HO, but not with HO, resulted in M + 2 isotopologues of the α-hydroxyaldehyde, whereas reactions with both O and HO identified the M + 4 isotopologue. Furthermore, incorporation of O from O was predominantly located at the α-carbon. In contrast, reactions with HO yielded O linked to the aldehyde carbon. Importantly, no significant labeling of 2-AA-lysolipids with O, HO, or HO was present. Intriguingly, phosphatidylinositol phosphates (PIP and PIP) effectively substituted for cardiolipin. Moreover, cytochrome released from myocardial mitochondria subjected to oxidative stress cleaved plasmenylcholine in membrane bilayers, and this was blocked with a specific mAb against cytochrome Collectively, these results identify the first plasmalogenase in biology, reveal the production of previously unanticipated signaling lipids by cytochrome , and present new perspectives on cellular signaling during oxidative stress.
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http://dx.doi.org/10.1074/jbc.RA117.001629DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5986220PMC
June 2018

The structure of iPLAβ reveals dimeric active sites and suggests mechanisms of regulation and localization.

Nat Commun 2018 02 22;9(1):765. Epub 2018 Feb 22.

Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, MO, 63104, USA.

Calcium-independent phospholipase Aβ (iPLAβ) regulates important physiological processes including inflammation, calcium homeostasis and apoptosis. It is genetically linked to neurodegenerative disorders including Parkinson's disease. Despite its known enzymatic activity, the mechanisms underlying iPLAβ-induced pathologic phenotypes remain poorly understood. Here, we present a crystal structure of iPLAβ that significantly revises existing mechanistic models. The catalytic domains form a tight dimer. They are surrounded by ankyrin repeat domains that adopt an outwardly flared orientation, poised to interact with membrane proteins. The closely integrated active sites are positioned for cooperative activation and internal transacylation. The structure and additional solution studies suggest that both catalytic domains can be bound and allosterically inhibited by a single calmodulin. These features suggest mechanisms of iPLAβ cellular localization and activity regulation, providing a basis for inhibitor development. Furthermore, the structure provides a framework to investigate the role of neurodegenerative mutations and the function of iPLAβ in the brain.
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http://dx.doi.org/10.1038/s41467-018-03193-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5823874PMC
February 2018

Ageing-associated DNA methylation dynamics are a molecular readout of lifespan variation among mammalian species.

Genome Biol 2018 Feb 16;19(1):22. Epub 2018 Feb 16.

The Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, E1 2AT, UK.

Background: Mammalian species exhibit a wide range of lifespans. To date, a robust and dynamic molecular readout of these lifespan differences has not yet been identified. Recent studies have established the existence of ageing-associated differentially methylated positions (aDMPs) in human and mouse. These are CpG sites at which DNA methylation dynamics show significant correlations with age. We hypothesise that aDMPs are pan-mammalian and are a dynamic molecular readout of lifespan variation among different mammalian species.

Results: A large-scale integrated analysis of aDMPs in six different mammals reveals a strong negative relationship between rate of change of methylation levels at aDMPs and lifespan. This relationship also holds when comparing two different dog breeds with known differences in lifespans. In an ageing cohort of aneuploid mice carrying a complete copy of human chromosome 21, aDMPs accumulate far more rapidly than is seen in human tissues, revealing that DNA methylation at aDMP sites is largely shaped by the nuclear trans-environment and represents a robust molecular readout of the ageing cellular milieu.

Conclusions: Overall, we define the first dynamic molecular readout of lifespan differences among mammalian species and propose that aDMPs will be an invaluable molecular tool for future evolutionary and mechanistic studies aimed at understanding the biological factors that determine lifespan in mammals.
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http://dx.doi.org/10.1186/s13059-018-1397-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5815211PMC
February 2018

Virulence of the Melioidosis Pathogen Burkholderia pseudomallei Requires the Oxidoreductase Membrane Protein DsbB.

Infect Immun 2018 05 23;86(5). Epub 2018 Apr 23.

Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Queensland, Australia

The naturally antibiotic-resistant bacterium is the causative agent of melioidosis, a disease with stubbornly high mortality and a complex, protracted treatment regimen. The worldwide incidence of melioidosis is likely grossly underreported, though it is known to be highly endemic in northern Australia and Southeast Asia. Bacterial disulfide bond (DSB) proteins catalyze the oxidative folding and isomerization of disulfide bonds in substrate proteins. In the present study, we demonstrate that membrane protein disulfide bond protein B (BpsDsbB) forms a functional redox relay with the previously characterized virulence mediator disulfide bond protein A (BpsDsbA). Genomic analysis of diverse clinical isolates demonstrated that is a highly conserved core gene. Critically, we show that DsbB is required for virulence in A panel of deletion strains (K96243, 576, MSHR2511, MSHR0305b, and MSHR5858) were phenotypically diverse according to the results of assays that assess hallmarks of virulence. Irrespective of their virulence phenotypes, two deletion strains were attenuated in a BALB/c mouse model of infection. A crystal structure of a DsbB-derived peptide complexed with BpsDsbA provides the first molecular characterization of their interaction. This work contributes to our broader understanding of DSB redox biology and will support the design of antimicrobial drugs active against this important family of bacterial virulence targets.
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http://dx.doi.org/10.1128/IAI.00938-17DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5913862PMC
May 2018

Evaluation of ADAMTS17 in Chinese Shar-Pei with primary open-angle glaucoma, primary lens luxation, or both.

Am J Vet Res 2018 Jan;79(1):98-106

OBJECTIVE To evaluate the coding regions of ADAMTS17 for potential mutations in Chinese Shar-Pei with a diagnosis of primary open-angle glaucoma (POAG), primary lens luxation (PLL), or both. ANIMALS 63 Shar-Pei and 96 dogs of other breeds. PROCEDURES ADAMTS17 exon resequencing was performed on buccal mucosal DNA from 10 Shar-Pei with a diagnosis of POAG, PLL, or both (affected dogs). A candidate causal variant sequence was identified, and additional dogs (53 Shar-Pei [11 affected and 42 unaffected] and 95 dogs of other breeds) were genotyped for the variant sequence by amplified fragment length polymorphism analysis. Total RNA was extracted from ocular tissues of 1 affected Shar-Pei and 1 ophthalmologically normal Golden Retriever; ADAMTS17 cDNA was reverse transcribed and sequenced, and ADAMTS17 expression was evaluated by quantitative reverse-transcription PCR assay. RESULTS All affected Shar-Pei were homozygous for a 6-bp deletion in exon 22 of ADAMTS17 predicted to affect the resultant protein. All unaffected Shar-Pei were heterozygous or homozygous for the wild-type allele. The variant sequence was significantly associated with affected status (diagnosis of POAG, PLL, or both). All dogs of other breeds were homozygous for the wild-type allele. The cDNA sequencing confirmed presence of the expected variant mRNA sequence in ocular tissue from the affected dog only. Gene expression analysis revealed a 4.24-fold decrease in the expression of ADAMTS17 in ocular tissue from the affected dog. CONCLUSIONS AND CLINICAL RELEVANCE Results supported that the phenotype (diagnosis of POAG, PLL, or both) is an autosomal recessive trait in Shar-Pei significantly associated with the identified mutation in ADAMTS17.
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http://dx.doi.org/10.2460/ajvr.79.1.98DOI Listing
January 2018

Heart failure-induced activation of phospholipase iPLAγ generates hydroxyeicosatetraenoic acids opening the mitochondrial permeability transition pore.

J Biol Chem 2018 01 20;293(1):115-129. Epub 2017 Nov 20.

Division of Bioorganic Chemistry and Molecular Pharmacology, the Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110; Department of Developmental Biology, Washington University School of Medicine, St. Louis, Missouri 63110; Center for Cardiovascular Research, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110; Department of Chemistry, Washington University, St. Louis, Missouri 63130. Electronic address:

Congestive heart failure typically arises from cardiac myocyte necrosis/apoptosis, associated with the pathological opening of the mitochondrial permeability transition pore (mPTP). mPTP opening decreases the mitochondrial membrane potential leading to the activation of Ca-independent phospholipase Aγ (iPLAγ) and the production of downstream toxic metabolites. However, the array of enzymatic mediators and the exact chemical mechanisms responsible for modulating myocardial mPTP opening remain unclear. Herein, we demonstrate that human heart failure activates specific myocardial mitochondrial phospholipases that increase Ca-dependent production of toxic hydroxyeicosatetraenoic acids (HETEs) and attenuate the activity of phospholipases that promote the synthesis of protective epoxyeicosatrienoic acids (EETs). Mechanistically, HETEs activated the Ca-induced opening of the mPTP in failing human myocardium, and the highly selective pharmacological blockade of either iPLAγ or lipoxygenases attenuated mPTP opening in failing hearts. In contrast, pharmacological inhibition of cytochrome P450 epoxygenases opened the myocardial mPTP in human heart mitochondria. Remarkably, the major mitochondrial phospholipase responsible for Ca-activated release of arachidonic acid (AA) in mitochondria from non-failing hearts was calcium-dependent phospholipase Aζ (cPLAζ) identified by sequential column chromatographies and activity-based protein profiling. In contrast, iPLAγ predominated in failing human myocardium. Stable isotope kinetics revealed that in non-failing human hearts, cPLAζ metabolically channels arachidonic acid into EETs, whereas in failing hearts, increased iPLAγ activity channels AA into toxic HETEs. These results mechanistically identify the sequelae of pathological remodeling of human mitochondrial phospholipases in failing myocardium. This remodeling metabolically channels AA into toxic HETEs promoting mPTP opening, which induces necrosis/apoptosis leading to further progression of heart failure.
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http://dx.doi.org/10.1074/jbc.RA117.000405DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5766913PMC
January 2018
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