High efficacy treatment of murine Pseudomonas aeruginosa catheter-associated urinary tract infections using the c-di-GMP modulating anti-biofilm compound Disperazol in combination with ciprofloxacin.

Persistent urinary tract infections (UTIs) in hospitalized patients constitute an important medical problem. It is estimated that 75% of nosocomial UTIs are associated with urinary tract catheters with P. aeruginosa being a species that forms biofilms on these catheters. These infections are highly resistant to standard-of-care antibiotics, and the effects of the host immune defenses, which allows for development of persistent infections. With antibiotics losing their efficacy, new treatment options against resilient infections, such as catheter-associated urinary tract infections (CAUTIs), are critically needed. Central to our anti-biofilm approach is the manipulation of the c-di-GMP signaling pathway in P. aeruginosa to switch bacteria from the protective biofilm to the unprotected planktonic mode of life. We recently identified a compound (H6-335-P1), that stimulates the c-di-GMP degrading activity of the P. aeruginosa BifA protein which plummets the intracellular c-di-GMP content and induces dispersal of P. aeruginosa biofilm bacteria into the planktonic state. In the present study, we formulated H6-335-P1 as a hydrochloride salt (Disperazol), which is water-soluble and facilitates delivery via injection or oral administration. Disperazol can work as a monotherapy, but we observed a 100-fold improvement in efficacy when treating murine P. aeruginosa CAUTIs with a Disperazol/ciprofloxacin combination. Biologically active Disperazol reached the bladder 30 min after oral administration. Our study provides proof of concept that Disperazol can be used in combination with a relevant antibiotic for effective treatment of CAUTIs.

Unveiling the Temporal Aspect of MRI Tattoo Reactions: A Prospective Evaluation of a Newly-Acquired Tattoo with Multiple MRI Scans.

BACKGROUND Over the past 30 years, painful reactions during magnetic resonance imaging (MRI) in tattooed individuals have been sporadically reported. These complications manifest as burning pain in tattooed skin areas, occasionally with swelling and redness, often leading to termination of the scanning. The exact cause is unclear, but iron oxide pigments in permanent make-up or elements in carbon black tattoos may play a role. Additionally, factors like tattoo age, design, and color may influence reactions. The existing literature lacks comprehensive evidence, leaving many questions unanswered. CASE REPORT We present the unique case of a young man who experienced recurring painful reactions in a recently applied black tattoo during multiple MRI scans. Despite the absence of ferrimagnetic ingredients in the tattoo ink, the patient reported intense burning sensations along with transient erythema and edema. Interestingly, the severity of these reactions gradually decreased over time, suggesting a time-dependent factor contributing to the problem. This finding highlights the potential influence of pigment particle density in the skin on the severity and risk of MRI interactions. We hypothesize that the painful sensations could be triggered by excitation of dermal C-fibers by conductive elements in the tattoo ink, likely carbon particles. CONCLUSIONS Our case study highlights that MRI-induced tattoo reactions may gradually decrease over time. While MRI scans occasionally can cause transient reactions in tattoos, they do not result in permanent skin damage and remain a safe and essential diagnostic tool. Further research is needed to understand the mechanisms behind these reactions and explore preventive measures.

3-Dimensional Ultrastructural Analysis of the Rat Pinealocyte: Presence of Secretory Bulbous Projections Delineated from the Cell Body by Junctional Complexes.

INTRODUCTION: The superficial pineal gland of the Sprague Dawley rat is a neuroendocrine structure secreting the hormone melatonin. By use of block face scanning electron microscopy, our aim here was to identify the 3-dimensional ultrastructure of the gland. METHODS: A series of 2,731 block face images of the rat pineal tissue, 30 nm in thickness, was obtained in a Teneo volume scanning electron microscope and used for 3-dimensional reconstruction by use of the TrakEM2-plugin in the ImageJ software. Thin sections of the tissue were cut for transmission electron microscopy. RESULTS: Our analyses revealed cellular bulbous processes, containing 50-100 nm clear vesicles, that emerged from a neck-like area at the cell body of the pinealocyte. These bulbous processes extend into small canaliculi located in the center of parenchymal folliculi of the gland as well as into the perivascular spaces. Junctional complexes, comprising both gap and tight junctions, connected the lateral cellular membranes of the pinealocytes, where the bulbous processes emerged from the cell bodies. The canaliculi were, via the extracellular space, connected to the perivascular spaces. DISCUSSION: The junctional complexes reported here would prevent a substance, released from the vesicles in the bulbous processes, from targeting the cell body from which they emerge. In line with previous combined morphological and biochemical demonstrations of glutamate located in clear vesicles of bulbous processes in the rat pineal gland, our data ultrastructurally support the concept that bulbous processes could participate in a paracrine glutamatergic inhibition of the melatonin secretion in the pineal gland. CONCLUSION: Bulbous secretory projections separated from the cell body by a junctional complex represents a new feature of neuroendocrine cells.

Mycoplasma phocimorsus sp. nov., isolated from Scandinavian patients with seal finger or septic arthritis after contact with seals.

Seal finger (sealer's finger, spekk finger), an extremely painful hand infection contracted by individuals handling seals, has previously been associated with Mycoplasma phocacerebrale. From 2000 to 2014, six independent strains of a novel Mycoplasma species were isolated at Statens Serum Institut, Denmark, from Scandinavian patients with seal finger (M5725T, M6447, M6620, M6642 and M6879) or septic arthritis (M6921). Prior to the onset of infection, all patients had reported contact with unspeciated seals. All isolates grew within 2-5 days in Friis' modified broth and metabolized glucose and arginine but not urea. Strains M5725T, M6447, M6642 and M6921 also grew in Hayflick-type media. Colonies on agar media were large (0.5-1.0 mm) and had a typical 'fried egg' appearance, reduced tetrazolium, and were digitonin sensitive. Growth occurred at 32 °C but not at 42 °C. Strains were susceptible to doxycycline and moxifloxacin but resistant to azithromycin and erythromycin. The genomes of the six strains were sequenced and relatedness to all known Mycoplasma species was inferred. Phylogenetic analyses using 16S rRNA gene sequences and core genome single nucleotide polymorphisms showed that the isolated strains were highly similar and phylogenetically distinct from all other species within the genus Mycoplasma. The sizes of the genome sequences of the strains ranged from 744 321 to 772409 bp, with a G+C content of 25.0-25.2 mol%. Based on these analyses, we propose a novel species of the genus Mycoplasma with the name Mycoplasma phocimorsus sp. nov. with the first isolate M5725T (NCTC 14922T=DSM 116188T) as the proposed type strain and representative strains M6447, M6620, M6642, M6879 and M6921.

MRI-Induced Neurosensory Events in Decorative Black Tattoos: Study by Advanced Experimental Methods.

Adverse reactions in tattooed skin during magnetic resonance imaging (MRI) are rare but well known. Previous reports describe sudden burning pain in tattooed skin, sometimes accompanied by mild erythema and oedema when entering MRI scanners. The pathophysiology remains unclear, but simple direct thermal heating can be excluded. It has been hypothesized that MRI-triggered torque and traction create neural sensations from magnetic pigment particles. However, this case enlightens yet another possible mechanism. We present a 35-year-old woman experiencing reoccurring stinging sensations in three decorative black tattoos just seconds after the initiation of the MRI. Single-blind tests with handheld power magnets or a dummy could reproduce painful subjective feelings in her tattooed skin. Similar events were provoked during re-evaluation with MRI. Surprisingly, chemical analyses and electron microscopy of skin samples revealed carbon black as the colouring agent - no iron-based solids were detected. Our case demonstrates that MRI tattoo reactions are not limited to magnetic contaminants alone. More distinct subgroups of MRI-induced reactions may occur. We hypothesize that radiofrequency induction of surface currents in black carbon particles adjacent to sensory axons in the dermis may lead to neurosensations.

Biofilm formation on endovascular aneurysm repair (EVAR) grafts-a proof of concept in vitro model.

OBJECTIVES: An endovascular aneurysm repair (EVAR) graft is a catheter-implanted vascular prosthesis and is the preferred treatment for patients with aortic aneurysm. If an EVAR graft becomes the focus of infection, the treatment possibilities are limited because it is technically difficult to remove the graft to obtain source control. This study examines whether Pseudomonas aeruginosa and Staphylococcus aureus form biofilm on EVAR prostheses. METHODS: EVAR graft sections were exposed to bacteria at 102 or 108 colony forming units (CFU)/mL in lysogeny broth and Krebs-Ringer at 37°C, bacterial biofilm formation was evaluated by scanning electron microscopy and counting CFU on the graft sections after antibiotic exposure at × 10 minimal inhibitory concentration. Bacteria were tested for tolerance to benzylpenicillin, tobramycin, and ciprofloxacin. RESULTS: Bacterial exposure for 15 minutes established biofilms on all prosthesis fragments (6/6 replicates). After 4 hours, bacteria were firmly attached to the EVAR prostheses and resisted washing. After 18-24 hours, the median CFU/g of EVAR graft reached 5.2 × 108 (1.15 × 108-1.1 × 109) for S. aureus and 9.1 × 107 (3.5 × 107-6.25 × 108) for P. aeruginosa. Scanning electron microscopy showed bacterial attachment to the graft pieces. There was a time-dependent development of tolerance with approximately 20 (tobramycin), 560 (benzylpenicillin), and 600 (ciprofloxacin) times more S. aureus surviving antibiotic exposure in 24- compared with 0-hour-old biofilm. Five (tobramycin) and 170 times (ciprofloxacin) more P. aeruginosa survived antibiotic exposure in 24- compared with 0-hour-old biofilms. DISCUSSION: Our results show that bacteria can rapidly adhere to and subsequently form antibiotic-tolerant biofilms on EVAR graft material in concentrations equivalent to levels seen in transient bacteraemia in vivo. Potentially, the system can be used for identifying optimal treatment combinations for infected EVAR prosthesis.

CRMP2 conditional knockout changes axonal function and ultrastructure of axons in mice corpus callosum.

Collapsin response mediator protein 2 (CRMP2) is a member of a protein family, which is highly involved in neurodevelopment, but most of its members become heavily downregulated in adulthood. CRMP2 is an important factor in neuronal polarization, axonal formation and growth cone collapse. The protein remains expressed in adulthood, but is more region specific. CRMP2 is present in adult corpus callosum (CC) and in plastic areas like prefrontal cortex and hippocampus. CRMP2 has been implicated as one of the risk-genes for Schizophrenia (SZ). Here, a CRMP2 conditional knockout (CRMP2-cKO) mouse was used as a model of SZ to investigate how it could affect the white matter and therefore brain connectivity. Multielectrode electrophysiology (MEA) was used to study the function of corpus callosum showing an increase in conduction velocity (CV) measured as Compound Action Potentials (CAPs) in acute brain slices. Light- and electron-microscopy, specifically Serial Block-face Scanning Electron Microscopy (SBF-SEM), methods were used to study the structure of CC in CRMP2-cKO mice. A decrease in CC volume of CRMP2-cKO mice as compared to controls was observed. No differences were found in numbers nor in the size of CC oligodendrocytes (OLs). Similarly, no differences were found in myelin thickness or in node of Ranvier (NR) structure. In contrast, abnormally smaller axons were measured in the CRMP2-cKO mice. Using these state-of-the-art methods it was possible to shed light on specific parts of the dysconnectivity aspect of deletion of CRMP2 related to SZ and add details to previous findings helping further understanding the disease. This paper substantiates the white matter changes in the absence of CRMP2 and ties it to the role it plays in this complex disorder.

Loss of Nuclear Envelope Integrity and Increased Oxidant Production Cause DNA Damage in Adult Hearts Deficient in PKP2: A Molecular Substrate of ARVC.

BACKGROUND: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is characterized by high propensity to life-threatening arrhythmias and progressive loss of heart muscle. More than 40% of reported genetic variants linked to ARVC reside in the PKP2 gene, which encodes the PKP2 protein (plakophilin-2). METHODS: We describe a comprehensive characterization of the ARVC molecular landscape as determined by high-resolution mass spectrometry, RNA sequencing, and transmission electron microscopy of right ventricular biopsy samples obtained from patients with ARVC with PKP2 mutations and left ventricular ejection fraction >45%. Samples from healthy relatives served as controls. The observations led to experimental work using multiple imaging and biochemical techniques in mice with a cardiac-specific deletion of Pkp2 studied at a time of preserved left ventricular ejection fraction and in human induced pluripotent stem cell-derived PKP2-deficient myocytes. RESULTS: Samples from patients with ARVC present a loss of nuclear envelope integrity, molecular signatures indicative of increased DNA damage, and a deficit in transcripts coding for proteins in the electron transport chain. Mice with a cardiac-specific deletion of Pkp2 also present a loss of nuclear envelope integrity, which leads to DNA damage and subsequent excess oxidant production (O2.- and H2O2), the latter increased further under mechanical stress (isoproterenol or exercise). Increased oxidant production and DNA damage is recapitulated in human induced pluripotent stem cell-derived PKP2-deficient myocytes. Furthermore, PKP2-deficient cells release H2O2 into the extracellular environment, causing DNA damage and increased oxidant production in neighboring myocytes in a paracrine manner. Treatment with honokiol increases SIRT3 (mitochondrial nicotinamide adenine dinucleotide-dependent protein deacetylase sirtuin-3) activity, reduces oxidant levels and DNA damage in vitro and in vivo, reduces collagen abundance in the right ventricular free wall, and has a protective effect on right ventricular function. CONCLUSIONS: Loss of nuclear envelope integrity and subsequent DNA damage is a key substrate in the molecular pathology of ARVC. We show transcriptional downregulation of proteins of the electron transcript chain as an early event in the molecular pathophysiology of the disease (before loss of left ventricular ejection fraction <45%), which associates with increased oxidant production (O2.- and H2O2). We propose therapies that limit oxidant formation as a possible intervention to restrict DNA damage in ARVC.

An ultrastructural study of the deep pineal gland of the Sprague Dawley rat using transmission and serial block face scanning electron microscopy: cell types, barriers, and innervation.

The morphology of the deep pineal gland of the Sprague Dawley rat was investigated by serial block face scanning electron microscopy. Cells were three-dimensionally (3-D) reconstructed using the software Fiji TrackEM. The deep pineal gland consisted of 2-5 layers of electron-lucent pinealocytes, with a euchromatic nucleus, endowed with one or two processes. Laterally, the deep pineal merged with the habenula and the stria medullaris thalami, via an intermediate area containing cells with more electron-dense cytoplasm and an indented nucleus with heterochromatin. Neither nerve terminals nor capillaries were observed in the deep pineal itself but present in the intermediate parts of the gland. The deep pineal was in contact with the third ventricle via the pineal and suprahabenular recesses. The ependymal lining in these recesses was an epithelium connected by tight junctions between their lateral cell membranes. Several intraventricular nerve terminals were in contact with the ependyma. 3-D reconstructions showed the ependymal cells endowed with long slender process penetrating the underlying pineal parenchyma. Few "tanocyte-like" ependymal cells, endowed with a process, reaching the subarachnoid space on the inferior surface of the deep pineal were observed. In addition, pinealocyte and astrocyte processes, often connected by gap junctions, bordered the inferior surface. In summary, the rat deep pineal gland is a neuroendocrine structure connected to the habenula. We here report specialized ependymal cells that might transmit signals from the cerebrospinal fluid to the deep pineal parenchyma and a "trans-pineal tanocyte-like cell" that connects the ventricular system with the subarachnoid space.

Quantification of Subcellular Glycogen Distribution in Skeletal Muscle Fibers using Transmission Electron Microscopy.

With the use of transmission electron microscopy, high-resolution images of fixed samples containing individual muscle fibers can be obtained. This enables quantifications of ultrastructural aspects such as volume fractions, surface area to volume ratios, morphometry, and physical contact sites of different subcellular structures. In the 1970s, a protocol for enhanced staining of glycogen in cells was developed and paved the way for a string of studies on the subcellular localization of glycogen and glycogen particle size using transmission electron microscopy. While most analyses interpret glycogen as if it is homogeneously distributed within the muscle fibers, providing only a single value (e.g., an average concentration), transmission electron microscopy has revealed that glycogen is stored as discrete glycogen particles located in distinct subcellular compartments. Here, the step-by-step protocol from tissue collection to the quantitative determination of the volume fraction and particle diameter of glycogen in the distinct subcellular compartments of individual skeletal muscle fibers is described. Considerations on how to 1) collect and stain tissue specimens, 2) perform image analyses and data handling, 3) evaluate the precision of estimates, 4) discriminate between muscle fiber types, and 5) methodological pitfalls and limitations are included.

Curvature thylakoid 1 proteins modulate prolamellar body morphology and promote organized thylakoid biogenesis in Arabidopsis thaliana.

The term "de-etiolation" refers to the light-dependent differentiation of etioplasts to chloroplasts in angiosperms. The underlying process involves reorganization of prolamellar bodies (PLBs) and prothylakoids into thylakoids, with concurrent changes in protein, lipid, and pigment composition, which together lead to the assembly of active photosynthetic complexes. Despite the highly conserved structure of PLBs among land plants, the processes that mediate PLB maintenance and their disassembly during de-etiolation are poorly understood. Among chloroplast thylakoid membrane-localized proteins, to date, only Curvature thylakoid 1 (CURT1) proteins were shown to exhibit intrinsic membrane-bending capacity. Here, we show that CURT1 proteins, which play a critical role in grana margin architecture and thylakoid plasticity, also participate in de-etiolation and modulate PLB geometry and density. Lack of CURT1 proteins severely perturbs PLB organization and vesicle fusion, leading to reduced accumulation of the light-dependent enzyme protochlorophyllide oxidoreductase (LPOR) and a delay in the onset of photosynthesis. In contrast, overexpression of CURT1A induces excessive bending of PLB membranes, which upon illumination show retarded disassembly and concomitant overaccumulation of LPOR, though without affecting greening or the establishment of photosynthesis. We conclude that CURT1 proteins contribute to the maintenance of the paracrystalline PLB morphology and are necessary for efficient and organized thylakoid membrane maturation during de-etiolation.

The cancer angiogenesis co-culture assay: In vitro quantification of the angiogenic potential of tumoroids.

The treatment response to anti-angiogenic agents varies among cancer patients and predictive biomarkers are needed to identify patients with resistant cancer or guide the choice of anti-angiogenic treatment. We present "the Cancer Angiogenesis Co-Culture (CACC) assay", an in vitro Functional Precision Medicine assay which enables the study of tumouroid induced angiogenesis. This assay can quantify the ability of a patient-derived tumouroid to induce vascularization by measuring the induction of tube formation in a co-culture of vascular cells and tumoroids established from the primary colorectal tumour or a metastasis. Furthermore, the assay can quantify the sensitivity of patient-derived tumoroids to anti-angiogenic therapies. We observed that tube formation increased in a dose-dependent manner upon treatment with the pro-angiogenic factor vascular endothelial growth factor A (VEGF-A). When investigating the angiogenic potential of tumoroids from 12 patients we found that 9 tumoroid cultures induced a significant increase in tube formation compared to controls without tumoroids. In these 9 angiogenic tumoroid cultures the tube formation could be abolished by treatment with one or more of the investigated anti-angiogenic agents. The 3 non-angiogenic tumoroid cultures secreted VEGF-A but we observed no correlation between the amount of tube formation and tumoroid-secreted VEGF-A. Our data suggests that the CACC assay recapitulates the complexity of tumour angiogenesis, and when clinically verified, could prove a valuable tool to quantify sensitivity towards different anti-angiogenic agents.

Delayed neutrophil recruitment allows nascent Staphylococcus aureus biofilm formation and immune evasion.

Biofilms that form on implanted medical devices cause recalcitrant infections. The early events enabling contaminating bacteria to evade immune clearance, before a mature biofilm is established, are poorly understood. Live imaging in vitro demonstrated that Staphylococcus aureus sparsely inoculated on an abiotic surface can go undiscovered by human neutrophils, grow, and form aggregates. Small (~50 µm2) aggregates of attached bacteria resisted killing by human neutrophils, resulting in neutrophil lysis and bacterial persistence. In vivo, neutrophil recruitment to a peritoneal implant was spatially heterogenous, with some bacterial aggregates remaining undiscovered by neutrophils after 24 h. Intravital imaging in mouse skin revealed that attached S. aureus aggregates grew and remained undiscovered by neutrophils for up to 3 h. These results suggest a model in which delayed recruitment of neutrophils to an abiotic implant presents a critical window in which bacteria establish a nascent biofilm and acquire tolerance to neutrophil killing.

Plasmodium falciparum erythrocyte membrane protein 1 variants induce cell swelling and disrupt the blood-brain barrier in cerebral malaria.

Cerebral malaria (CM) is caused by the binding of Plasmodium falciparum-infected erythrocytes (IEs) to the brain microvasculature, leading to inflammation, vessel occlusion, and cerebral swelling. We have previously linked dual intercellular adhesion molecule-1 (ICAM-1)- and endothelial protein C receptor (EPCR)-binding P. falciparum parasites to these symptoms, but the mechanism driving the pathogenesis has not been identified. Here, we used a 3D spheroid model of the blood-brain barrier (BBB) to determine unexpected new features of IEs expressing the dual-receptor binding PfEMP1 parasite proteins. Analysis of multiple parasite lines shows that IEs are taken up by brain endothelial cells in an ICAM-1-dependent manner, resulting in breakdown of the BBB and swelling of the endothelial cells. Via ex vivo analysis of postmortem tissue samples from CM patients, we confirmed the presence of parasites within brain endothelial cells. Importantly, this discovery points to parasite ingress into the brain endothelium as a contributing factor to the pathology of human CM.

The need to freeze-Dehydration during specimen preparation for electron microscopy collapses the endothelial glycocalyx regardless of fixation method.

OBJECTIVE: The endothelial glycocalyx covers the luminal surface of the endothelium and plays key roles in vascular function. Despite its biological importance, ideal visualization techniques are lacking. The current study aimed to improve the preservation and subsequent imaging quality of the endothelial glycocalyx. METHODS: In mice, the endothelial glycocalyx was contrasted with a mixture of lanthanum and dysprosium (LaDy). Standard chemical fixation was compared with high-pressure frozen specimens processed with freeze substitution. Also, isolated brain microvessels and cultured endothelial cells were high-pressure frozen and by transmission soft x-rays, imaged under cryogenic conditions. RESULTS: The endothelial glycocalyx was in some tissues significantly more voluminous from chemically fixed specimens compared with high-pressure frozen specimens. LaDy labeling introduced excessive absorption contrast, which impeded glycocalyx measurements in isolated brain microvessels when using transmission soft x-rays. In non-contrasted vessels, the glycocalyx was not resolved. LaDy-contrasted, cultured brain endothelial cells allowed to assess glycocalyx volume in vitro. CONCLUSIONS: Both chemical and cryogenic fixation followed by dehydration lead to substantial collapse of the glycocalyx. Cryogenic fixation without freeze substitution could be a way forward although transmission soft x-ray tomography based solely on amplitude contrast seems unsuitable.

The origin of extracellular DNA in bacterial biofilm infections in vivo.

Extracellular DNA (eDNA) plays an important role in both the aggregation of bacteria and in the interaction of the resulting biofilms with polymorphonuclear leukocytes (PMNs) during an inflammatory response. Here, transmission electron and confocal scanning laser microscopy were used to examine the interaction between biofilms of Pseudomonas aeruginosa and PMNs in a murine implant model and in lung tissue from chronically infected cystic fibrosis patients. PNA FISH, DNA staining, labeling of PMN DNA with a thymidine analogue and immunohistochemistry were applied to localize bacteria, eDNA, PMN-derived eDNA, PMN-derived histone H3 (H3), neutrophil elastase (NE) and citrullinated H3 (citH3). Host-derived eDNA was observed surrounding bacterial biofilms but not within the biofilms. H3 localized to the lining of biofilms while NE was found throughout biofilms. CitH3, a marker for neutrophil extracellular traps (NETs) was detected only sporadically indicating that most host-derived eDNA in vivo was not a result of NETosis. Together these observations show that, in these in vivo biofilm infections with P. aeruginosa, the majority of eDNA is found external to the biofilm and derives from the host.

Turtles maintain mitochondrial integrity but reduce mitochondrial respiratory capacity in the heart after cold acclimation and anoxia.

Mitochondria are important to cellular homeostasis, but can become a dangerous liability when cells recover from hypoxia. Anoxia-tolerant freshwater turtles show reduced mitochondrial respiratory capacity and production of reactive oxygen species (ROS) after prolonged anoxia, but the mechanisms are unclear. Here, we investigated whether this mitochondrial suppression originates from downregulation of mitochondrial content or intrinsic activity by comparing heart mitochondria from (1) warm (25°C) normoxic, (2) cold-acclimated (4°C) normoxic and (3) cold-acclimated anoxic turtles. Transmission electron microscopy of heart ventricle revealed that these treatments did not affect mitochondrial volume density and morphology. Furthermore, neither enzyme activity, protein content nor supercomplex distribution of electron transport chain (ETC) enzymes changed significantly. Instead, our data imply that turtles inhibit mitochondrial respiration rate and ROS production by a cumulative effect of slight inhibition of ETC complexes. Together, these results show that maintaining mitochondrial integrity while inhibiting overall enzyme activities are important aspects of anoxia tolerance.

Shotgun sequencing of clinical biofilm following scanning electron microscopy identifies bacterial community composition.

Bacterial biofilm infections often involve aggregates of bacteria heterogeneously distributed throughout a tissue or on a surface (such as an implanted medical device). Identification of a biofilm infection requires direct visualization via microscopy, followed by characterization of the microbial community by culturing or sequencing-based approaches. A sample, therefore, must be divided prior to analysis, often leading to inconsistent results. We demonstrate a combined approach, using scanning electron microscopy and next-generation shotgun sequencing, to visually identify a biofilm and characterize the microbial community, without dividing the sample. A clinical sample recovered from a patient following a dental root-filling procedure was prepared and visualized by scanning electron microscopy. DNA was then extracted from the sample several years later and analyzed by shotgun sequencing. The method was subsequently validated on in vitro cultures of Pseudomonas aeruginosa biofilm. Between 19 and 21 different genera and species were identified in the clinical sample with an estimated relative abundance greater than 1% by two different estimation approaches. Only eight genera identified were not associated with endodontic infections. This provides a proof-of-concept for a dual, microscopy and sequencing-based approach to identify and characterize bacterial biofilms, which could also easily be implemented in other scientific fields.

Cardiolipin Synthesis in Brown and Beige Fat Mitochondria Is Essential for Systemic Energy Homeostasis.

Activation of energy expenditure in thermogenic fat is a promising strategy to improve metabolic health, yet the dynamic processes that evoke this response are poorly understood. Here we show that synthesis of the mitochondrial phospholipid cardiolipin is indispensable for stimulating and sustaining thermogenic fat function. Cardiolipin biosynthesis is robustly induced in brown and beige adipose upon cold exposure. Mimicking this response through overexpression of cardiolipin synthase (Crls1) enhances energy consumption in mouse and human adipocytes. Crls1 deficiency in thermogenic adipocytes diminishes inducible mitochondrial uncoupling and elicits a nuclear transcriptional response through endoplasmic reticulum stress-mediated retrograde communication. Cardiolipin depletion in brown and beige fat abolishes adipose thermogenesis and glucose uptake, which renders animals insulin resistant. We further identify a rare human CRLS1 variant associated with insulin resistance and show that adipose CRLS1 levels positively correlate with insulin sensitivity. Thus, adipose cardiolipin has a powerful impact on organismal energy homeostasis through thermogenic fat bioenergetics.