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1.
PLoS Biol ; 22(6): e3002664, 2024 Jun.
Article in English | MEDLINE | ID: mdl-38829885

ABSTRACT

Neuroscientists studying the neural correlates of mouse behavior often lack access to the brain-wide activity patterns elicited during a specific task of interest. Fortunately, large-scale imaging is becoming increasingly accessible thanks to modalities such as Ca2+ imaging and functional ultrasound (fUS). However, these and other techniques often involve challenging cranial window procedures and are difficult to combine with other neuroscience tools. We address this need with an open-source 3D-printable cranial implant-the COMBO (ChrOnic Multimodal imaging and Behavioral Observation) window. The COMBO window enables chronic imaging of large portions of the brain in head-fixed mice while preserving orofacial movements. We validate the COMBO window stability using both brain-wide fUS and multisite two-photon imaging. Moreover, we demonstrate how the COMBO window facilitates the combination of optogenetics, fUS, and electrophysiology in the same animals to study the effects of circuit perturbations at both the brain-wide and single-neuron level. Overall, the COMBO window provides a versatile solution for performing multimodal brain recordings in head-fixed mice.


Subject(s)
Brain , Optogenetics , Animals , Mice , Brain/physiology , Brain/diagnostic imaging , Optogenetics/methods , Neurons/physiology , Mice, Inbred C57BL , Skull/physiology , Male , Behavior, Animal/physiology , Multimodal Imaging/methods , Ultrasonography/methods , Printing, Three-Dimensional
2.
Proc Biol Sci ; 291(2014): 20232383, 2024 Jan 10.
Article in English | MEDLINE | ID: mdl-38196355

ABSTRACT

Natural pest and weed regulation are essential for agricultural production, but the spatial distribution of natural enemies within crop fields and its drivers are mostly unknown. Using 28 datasets comprising 1204 study sites across eight Western and Central European countries, we performed a quantitative synthesis of carabid richness, activity densities and functional traits in relation to field edges (i.e. distance functions). We show that distance functions of carabids strongly depend on carabid functional traits, crop type and, to a lesser extent, adjacent non-crop habitats. Richness of both carnivores and granivores, and activity densities of small and granivorous species decreased towards field interiors, whereas the densities of large species increased. We found strong distance decays in maize and vegetables whereas richness and densities remained more stable in cereals, oilseed crops and legumes. We conclude that carabid assemblages in agricultural landscapes are driven by the complex interplay of crop types, adjacent non-crop habitats and further landscape parameters with great potential for targeted agroecological management. In particular, our synthesis indicates that a higher edge-interior ratio can counter the distance decay of carabid richness per field and thus likely benefits natural pest and weed regulation, hence contributing to agricultural sustainability.


Subject(s)
Agriculture , Fabaceae , Crops, Agricultural , Europe , Phenotype
3.
Circ Res ; 130(2): 166-180, 2022 01 21.
Article in English | MEDLINE | ID: mdl-34886679

ABSTRACT

RATIONALE: Dextro-transposition of the great arteries (D-TGA) is a severe congenital heart defect which affects approximately 1 in 4,000 live births. While there are several reports of D-TGA patients with rare variants in individual genes, the majority of D-TGA cases remain genetically elusive. Familial recurrence patterns and the observation that most cases with D-TGA are sporadic suggest a polygenic inheritance for the disorder, yet this remains unexplored. OBJECTIVE: We sought to study the role of common single nucleotide polymorphisms (SNPs) in risk for D-TGA. METHODS AND RESULTS: We conducted a genome-wide association study in an international set of 1,237 patients with D-TGA and identified a genome-wide significant susceptibility locus on chromosome 3p14.3, which was subsequently replicated in an independent case-control set (rs56219800, meta-analysis P=8.6x10-10, OR=0.69 per C allele). SNP-based heritability analysis showed that 25% of variance in susceptibility to D-TGA may be explained by common variants. A genome-wide polygenic risk score derived from the discovery set was significantly associated to D-TGA in the replication set (P=4x10-5). The genome-wide significant locus (3p14.3) co-localizes with a putative regulatory element that interacts with the promoter of WNT5A, which encodes the Wnt Family Member 5A protein known for its role in cardiac development in mice. We show that this element drives reporter gene activity in the developing heart of mice and zebrafish and is bound by the developmental transcription factor TBX20. We further demonstrate that TBX20 attenuates Wnt5a expression levels in the developing mouse heart. CONCLUSIONS: This work provides support for a polygenic architecture in D-TGA and identifies a susceptibility locus on chromosome 3p14.3 near WNT5A. Genomic and functional data support a causal role of WNT5A at the locus.


Subject(s)
Polymorphism, Single Nucleotide , Transposition of Great Vessels/genetics , Animals , Cells, Cultured , Humans , Mice , Multifactorial Inheritance , Myocytes, Cardiac/metabolism , T-Box Domain Proteins/genetics , T-Box Domain Proteins/metabolism , Transposition of Great Vessels/metabolism , Wnt-5a Protein/genetics , Wnt-5a Protein/metabolism , Zebrafish
4.
Article in English | MEDLINE | ID: mdl-38387612

ABSTRACT

Congenital LQTS is an often undetected inherited cardiac channel dysfunction and can be a reason for intrauterine fetal demise. It can present in utero as CTG and ultrasound abnormalities, i. e., bradycardia, ventricular tachycardia, or fetal hydrops. Diagnosis is made by CTG, echocardiography, or fMCG. Intrauterine therapy with a ß blocker and i. v. magnesium should be started. Our objective was to examine the current knowledge about diagnosis and treatment of LQTS and in particular to highlight the opportunity of vaginal birth under continuous intravenous magnesium therapy. Therefore, a thorough MEDLINE and Google Scholar search was conducted. Randomized controlled trials, meta-analyses, prospective and retrospective cohort trials, and case reports were considered. We showed the possibility of vaginal delivery under continuous magnesium therapy in a case of suspected fetal LQTS. A stepwise concept for diagnosis, monitoring, and peripartum management in low, intermediate, and high risk cases of fetal LQTS is presented. If risk is low or intermediate, a vaginal delivery under continuous monitoring is reasonable. Induction of labor at term should be evaluated.

5.
J Pharmacol Exp Ther ; 386(2): 143-155, 2023 08.
Article in English | MEDLINE | ID: mdl-37164370

ABSTRACT

Sutimlimab, a humanized monoclonal antibody targeting the classic complement pathway, is approved in the United States, Japan, and the European Union for the treatment of hemolytic anemia in adults with cold agglutinin disease. The objectives of this study were to support dose selection for phase 3 studies, assess dose recommendations, and establish the relationship between sutimlimab exposure and clinical outcome [hemoglobin (Hb) levels]. Clinically meaningful biomarkers were graphically analyzed and the exposure-response relationship was proposed. The pharmacokinetic (PK) characteristics of sutimlimab were best described by a two-compartment model with parallel linear and nonlinear clearance terms. Body weight was a significant covariate for the volume of distribution in the central compartment (Vc) and total body clearance of sutimlimab. Ethnicity (Japanese, non-Japanese) was a covariate on Vc and maximal nonlinear clearance. There were no PK differences between healthy participants and patients. After graphical exposure-response analysis for biomarkers, a pharmacokinetic-pharmacodynamic model was developed by integrating an indirect response/turnover model for Hb with a maximum effect (Emax) model, relating the Hb-elevating effect of sutimlimab to plasma exposure. Renal function and occurrence of blood transfusion were identified as covariates on Hb change from baseline. Simulations showed that Emax was attained with the approved dosing (6.5 g in patients <75 kg and 7.5 g in patients ≥75 kg), independent of covariate characteristics, and provided adequate sutimlimab exposure to maximize effects on Hb, bilirubin, and total complement component C4 levels. A change in Hb from baseline at steady state of 2.2 g/dl was projected, consistent with phase 3 study observations. SIGNIFICANCE STATEMENT: The final validated population pharmacokinetic (PK) and pharmacokinetic/pharmacodynamic (PK/PD) models confirm that the approved dosing regimen for sutimlimab (6.5 g in patients <75 kg and 7.5 g in patients ≥75 kg) is sufficient, without the need for further dose adjustments in populations of patients with cold agglutinin disease.


Subject(s)
Anemia, Hemolytic, Autoimmune , Adult , Humans , Anemia, Hemolytic, Autoimmune/drug therapy , Antibodies, Monoclonal, Humanized/pharmacology , Antibodies, Monoclonal, Humanized/therapeutic use , Biomarkers , Body Weight
6.
Nat Methods ; 17(3): 343-351, 2020 03.
Article in English | MEDLINE | ID: mdl-32123394

ABSTRACT

Virtual realities are powerful tools to analyze and manipulate interactions between animals and their environment and to enable measurements of neuronal activity during behavior. In many species, however, optical access to the brain and/or the behavioral repertoire are limited. We developed a high-resolution virtual reality for head-restrained adult zebrafish, which exhibit cognitive behaviors not shown by larvae. We noninvasively measured activity throughout the dorsal telencephalon by multiphoton calcium imaging. Fish in the virtual reality showed regular swimming patterns and were attracted to animations of conspecifics. Manipulations of visuo-motor feedback revealed neurons that responded selectively to the mismatch between the expected and the actual visual consequences of motor output. Such error signals were prominent in multiple telencephalic areas, consistent with models of predictive processing. A virtual reality system for adult zebrafish therefore provides opportunities to analyze neuronal processing mechanisms underlying higher brain functions including decision making, associative learning, and social interactions.


Subject(s)
Behavior, Animal , Brain/diagnostic imaging , Neurons/physiology , User-Computer Interface , Virtual Reality , Animals , Brain Mapping , Cognition , Decision Making , Female , Male , Motor Skills , Probability , Social Behavior , Swimming , Zebrafish
7.
Blood ; 137(9): 1219-1232, 2021 03 04.
Article in English | MEDLINE | ID: mdl-33270819

ABSTRACT

Clinically relevant brain metastases (BMs) frequently form in cancer patients, with limited options for effective treatment. Circulating cancer cells must first permanently arrest in brain microvessels to colonize the brain, but the critical factors in this process are not well understood. Here, in vivo multiphoton laser-scanning microscopy of the entire brain metastatic cascade allowed unprecedented insights into how blood clot formation and von Willebrand factor (VWF) deposition determine the arrest of circulating cancer cells and subsequent brain colonization in mice. Clot formation in brain microvessels occurred frequently (>95%) and specifically at intravascularly arrested cancer cells, allowing their long-term arrest. An extensive clot embedded ∼20% of brain-arrested cancer cells, and those were more likely to successfully extravasate and form a macrometastasis. Mechanistically, the generation of tissue factor-mediated thrombin by cancer cells accounted for local activation of plasmatic coagulation in the brain. Thrombin inhibition by treatment with low molecular weight heparin or dabigatran and an anti-VWF antibody prevented clot formation, cancer cell arrest, extravasation, and the formation of brain macrometastases. In contrast, tumor cells were not able to directly activate platelets, and antiplatelet treatments did reduce platelet dispositions at intravascular cancer cells but did not reduce overall formation of BMs. In conclusion, our data show that plasmatic coagulation is activated early by intravascular tumor cells in the brain with subsequent clot formation, which led us to discover a novel and specific mechanism that is crucial for brain colonization. Direct or indirect thrombin and VWF inhibitors emerge as promising drug candidates for trials on prevention of BMs.


Subject(s)
Blood Coagulation , Brain Neoplasms/blood , Breast Neoplasms/pathology , Melanoma/pathology , Neoplastic Cells, Circulating/pathology , Thrombosis/blood , Animals , Brain Neoplasms/etiology , Brain Neoplasms/pathology , Breast Neoplasms/blood , Breast Neoplasms/complications , Cell Cycle Checkpoints , Disease Models, Animal , Female , Humans , Melanoma/blood , Melanoma/complications , Mice , Thrombosis/etiology , Thrombosis/pathology , von Willebrand Factor/analysis
8.
Cardiol Young ; 33(12): 2676-2677, 2023 Dec.
Article in English | MEDLINE | ID: mdl-37850484

ABSTRACT

We describe the echocardiographic findings of a common arterial trunk with intact ventricular septum, mitral and left ventricular hypoplasia, atretic left ventricular outlet and bilateral, and unbalanced pulmonary artery stenoses.


Subject(s)
Heart Defects, Congenital , Hypoplastic Left Heart Syndrome , Pulmonary Valve Stenosis , Truncus Arteriosus, Persistent , Ventricular Septum , Humans , Ventricular Septum/diagnostic imaging , Echocardiography , Pulmonary Valve Stenosis/diagnosis , Pulmonary Valve Stenosis/diagnostic imaging
9.
J Cardiovasc Magn Reson ; 24(1): 70, 2022 Dec 12.
Article in English | MEDLINE | ID: mdl-36503589

ABSTRACT

BACKGROUND: Pulmonary vein (PV) stenosis represents a rare but serious complication following radiofrequency ablation of atrial fibrillation with a comprehensive diagnosis including morphological stenosis grading together with the assessment of its functional consequences being imperative within the relatively narrow window for therapeutic intervention. The present study determined the clinical utility of a combined, single-session cardiovascular magnetic resonance (CMR) imaging protocol integrating pulmonary perfusion and PV angiographic assessment for pre-procedural planning and follow-up of patients referred for interventional PV stenosis treatment. METHODS: CMR examinations (cine imaging, dynamic pulmonary perfusion, three-dimensional PV angiography) were performed in 32 consecutive patients prior to interventional treatment of PV stenosis and at 1-day and 3-months follow-up. Degree of PV stenosis was visually determined on CMR angiography; visual and quantitative analysis of pulmonary perfusion imaging was done for all five lung lobes. RESULTS: Interventional treatment of PV stenosis achieved an acute procedural success rate of 90%. Agreement between visually evaluated pulmonary perfusion imaging and the presence or absence of a ≥ 70% PV stenosis was nearly perfect (Cohen's kappa, 0.96). ROC analysis demonstrated high discriminatory power of quantitative pulmonary perfusion measurements for the detection of ≥ 70% PV stenosis (AUC for time-to-peak enhancement, 0.96; wash-in rate, 0.93; maximum enhancement, 0.90). Quantitative pulmonary perfusion analysis proved a very large treatment effect attributable to successful PV revascularization already after 1 day. CONCLUSION: Integration of CMR pulmonary perfusion imaging into the clinical work-up of patients with PV stenosis allowed for efficient peri-procedural stratification and follow-up evaluation of revascularization success.


Subject(s)
Atrial Fibrillation , Catheter Ablation , Pulmonary Veins , Stenosis, Pulmonary Vein , Humans , Stenosis, Pulmonary Vein/diagnostic imaging , Stenosis, Pulmonary Vein/etiology , Stenosis, Pulmonary Vein/therapy , Pulmonary Veins/diagnostic imaging , Pulmonary Veins/surgery , Catheter Ablation/adverse effects , Constriction, Pathologic/etiology , Constriction, Pathologic/pathology , Constriction, Pathologic/surgery , Predictive Value of Tests , Atrial Fibrillation/diagnostic imaging , Atrial Fibrillation/surgery , Lung/diagnostic imaging , Magnetic Resonance Spectroscopy
10.
Restor Ecol ; 30(8): e13641, 2022 Nov.
Article in English | MEDLINE | ID: mdl-36589388

ABSTRACT

Establishment of semi-natural grasslands offers a valuable approach to the conservation of threatened grassland biodiversity. We established new grassland strips on former crop fields adjacent to old semi-natural grasslands and monitored the development of plant, carabid, spider, and wild bee communities over 3 years. The studied plant and arthropods communities were significantly different between newly established grassland strips and old grassland. Our results suggest that restoring plant and arthropod communities takes longer than 3 years to become similar to old semi-natural grasslands.

11.
Neurosurg Focus ; 50(4): E8, 2021 04.
Article in English | MEDLINE | ID: mdl-33794492

ABSTRACT

OBJECTIVE: The advent of endoscopic synostectomy has enabled early surgery for infants with craniosynostosis. Even though diagnosis is often made at birth, endoscopic synostectomy has traditionally been delayed until the infant is 3 months of age. There have been very few published reports of this procedure being performed in the early neonatal period. The authors discuss their experience with ultra-early endoscopic synostectomy, defined as an operation for infants aged 8 weeks or younger. METHODS: A retrospective analysis of infants who underwent operations at or before 8 weeks of age between 2011 and 2020 was done. RESULTS: Twenty-five infants underwent operations: 11 were 2 weeks of age or younger, 8 were between 3 and 4 weeks of age, and 6 were between 5 and 8 weeks of age. The infants weighed between 2.25 and 4.8 kg. Eighteen had single-suture synostosis, and 7 had multiple sutures involved. Of these 7, 4 had syndromic craniosynostosis. The average operative time was 35 minutes, and it was less than 40 minutes in 19 cases. The estimated operative blood loss was 25 ml or less in 19 cases; 5 infants required an intraoperative blood transfusion. In 1 child with syndromic multisuture craniosynostosis, the surgery was staged due to blood loss. Two children experienced complications related to the procedure: one had an incidental durotomy with skin infection, and the other had postoperative kernicterus. All infants were fitted for cranial remodeling orthoses following surgery. Three of the 25 infants required reoperations, with 2 patients with syndromic craniosynostosis needing repeat surgery for cranial volume expansion and cosmetic appearance. Another child with syndromic craniosynostosis is awaiting cranial expansion surgery. Follow-up varied between 6 months and 8 years. CONCLUSIONS: The data show that ultra-early synostectomy is safe and not associated with increased complications compared with surgery performed between 3 and 6 months of age. Infants with multisuture synostosis had increased operative time, required blood transfusion, and were more likely to require a second operation.


Subject(s)
Craniosynostoses , Child , Craniosynostoses/surgery , Humans , Infant , Infant, Newborn , Orthotic Devices , Retrospective Studies , Skull , Treatment Outcome
12.
Chemistry ; 26(72): 17356-17360, 2020 Dec 23.
Article in English | MEDLINE | ID: mdl-32777105

ABSTRACT

Compartmentalization and spatial organization of biochemical reactions are essential for the establishment of complex metabolic pathways inside synthetic cells. Phospholipid and fatty acid membranes are the most natural candidates for this purpose, but also polymers have shown great potential as enclosures of artificial cell mimics. Herein, we report on the formation of giant vesicles in a size range of 1 µm-100 µm using amphiphilic elastin-like polypeptides. The peptide vesicles can accommodate cell-free gene expression reactions, which is demonstrated by the transcription of a fluorescent RNA aptamer and the production of a fluorescent protein. Importantly, gene expression inside the vesicles leads to a strong growth of their size-up to an order of magnitude in volume in several cases-which is driven by changes in osmotic pressure, resulting in fusion events and uptake of membrane peptides from the environment.


Subject(s)
Artificial Cells , Peptides/metabolism , Phospholipids/chemistry , Elastin/chemistry , Peptides/chemistry , Phospholipids/metabolism , Polymers/chemistry
13.
Pacing Clin Electrophysiol ; 43(11): 1382-1389, 2020 11.
Article in English | MEDLINE | ID: mdl-33058294

ABSTRACT

BACKGROUND: Bradycardic arrhythmias requiring pacemaker (PM) implantation are still common in patients in need of tricuspid valve replacement (TVR). Leaving an existing PM lead in an extravalvular position may represent a helpful alternative in special situations like the implantation of a mechanical TV. This study aimed to examine the short- to mid-term outcome of paravalvular leads concerning lead survival and prosthesis dysfunction in patients after TVR. METHODS: A retrospective case-control study of patients with TVR and ventricular pacing was conducted. Patients from the database of the Leipzig Heart Center were included. Data of the paravalvular lead group (PVG) and coronary sinus lead group (CSG) were compared to a control group with conventional transvalvular leads (TVG). RESULTS: Eighty patients with TVR and cardiac PM (TVG [n = 13], PVG [n = 40], and CSG [n = 27]) were included. The mean follow-up was 2.8 years. The rate of lead revisions (TVG 15.4%, PVG 2.5%, and CSG 7.5%) was lower in PVG but without significance (P = .286). The CSG demonstrated significantly higher pacing thresholds (1.4 V/0.8 ms) than TVG (0.5 V/0.4 ms), P = .004. However, the deterioration of threshold amplitudes during follow-up was similar in CSG (7.4%) and PVG (7.5%) compared with controls (7.7%). Function of TV prosthesis regarding development of stenosis or regurgitation showed a similarity between the groups (regurgitation PVG P = .692, CSG P = 1; stenosis PVG P = .586, CSG P = 0.69). CONCLUSION: Paravalvular positioning of PM leads seems to represent a reasonable alternative to the conventional transvalvular lead positioning concerning the lead and Tricuspid Valve prosthesis's function and durability in selected patients.


Subject(s)
Bradycardia/therapy , Electrodes, Implanted , Heart Valve Prosthesis , Pacemaker, Artificial , Tricuspid Valve Insufficiency/surgery , Aged , Equipment Failure Analysis , Female , Humans , Male , Middle Aged , Prosthesis Failure
14.
Ecol Lett ; 22(9): 1493-1500, 2019 Sep.
Article in English | MEDLINE | ID: mdl-31286628

ABSTRACT

Agri-environment management (AEM) started in the 1980s in Europe to mitigate biodiversity decline, but the effectiveness of AEM has been questioned. We hypothesize that this is caused by a lack of a large enough ecological contrast between AEM and non-treated control sites. The effectiveness of AEM may be moderated by landscape structure and land-use intensity. Here, we examined the influence of local ecological contrast, landscape structure and regional land-use intensity on AEM effectiveness in a meta-analysis of 62 European pollinator studies. We found that ecological contrast was most important in determining the effectiveness of AEM, but landscape structure and regional land-use intensity played also a role. In conclusion, the most successful way to enhance AEM effectiveness for pollinators is to implement measures that result in a large ecological improvement at a local scale, which exhibit a strong contrast to conventional practices in simple landscapes of intensive land-use regions.


Subject(s)
Agriculture , Biodiversity , Conservation of Natural Resources , Pollination , Animals , Ecology , Ecosystem , Europe
15.
Ecol Lett ; 22(7): 1083-1094, 2019 Jul.
Article in English | MEDLINE | ID: mdl-30957401

ABSTRACT

Managing agricultural landscapes to support biodiversity and ecosystem services is a key aim of a sustainable agriculture. However, how the spatial arrangement of crop fields and other habitats in landscapes impacts arthropods and their functions is poorly known. Synthesising data from 49 studies (1515 landscapes) across Europe, we examined effects of landscape composition (% habitats) and configuration (edge density) on arthropods in fields and their margins, pest control, pollination and yields. Configuration effects interacted with the proportions of crop and non-crop habitats, and species' dietary, dispersal and overwintering traits led to contrasting responses to landscape variables. Overall, however, in landscapes with high edge density, 70% of pollinator and 44% of natural enemy species reached highest abundances and pollination and pest control improved 1.7- and 1.4-fold respectively. Arable-dominated landscapes with high edge densities achieved high yields. This suggests that enhancing edge density in European agroecosystems can promote functional biodiversity and yield-enhancing ecosystem services.


Subject(s)
Biodiversity , Crops, Agricultural , Ecosystem , Agriculture , Animals , Europe , Pollination
16.
Sensors (Basel) ; 19(6)2019 Mar 22.
Article in English | MEDLINE | ID: mdl-30909410

ABSTRACT

During the past decade, piezo-resistive cantilever type silicon microprobes for high-speed roughness measurements inside high-aspect-ratio microstructures, like injection nozzles or critical gas nozzles have been developed. This article summarizes their metrological properties for fast roughness and shape measurements including noise, damping, tip form, tip wear, and probing forces and presents the first results on the measurement of mechanical surface parameters. Due to the small mass of the cantilever microprobes, roughness measurements at very high traverse speeds up to 15 mm/s are possible. At these high scanning speeds, considerable wear of the integrated silicon tips was observed in the past. In this paper, a new tip-testing artefact with rectangular grooves of different width was used to measure this wear and to measure the tip shape, which is needed for morphological filtering of the measured profiles and, thus, for accurate form measurements. To reduce tip wear, the integrated silicon tips were replaced by low-wear spherical diamond tips of a 2 µm radius. Currently, a compact microprobe device with an integrated feed-unit is being developed for high-speed roughness measurements on manufacturing machines. First measurements on sinusoidal artefacts were carried out successfully. Moreover, the first measurements of the elastic modulus of a polymer surface applying the contact resonance measurement principle are presented, which indicates the high potential of these microprobes for simultaneous high-speed roughness and mechanical parameter measurements.

17.
EMBO J ; 33(3): 247-64, 2014 Feb 03.
Article in English | MEDLINE | ID: mdl-24442635

ABSTRACT

Cochlear inner hair cells (IHCs) develop from pre-sensory pacemaker to sound transducer. Here, we report that this involves changes in structure and function of the ribbon synapses between IHCs and spiral ganglion neurons (SGNs) around hearing onset in mice. As synapses matured they changed from holding several small presynaptic active zones (AZs) and apposed postsynaptic densities (PSDs) to one large AZ/PSD complex per SGN bouton. After the onset of hearing (i) IHCs had fewer and larger ribbons; (ii) CaV1.3 channels formed stripe-like clusters rather than the smaller and round clusters at immature AZs; (iii) extrasynaptic CaV1.3-channels were selectively reduced, (iv) the intrinsic Ca(2)(+) dependence of fast exocytosis probed by Ca(2)(+) uncaging remained unchanged but (v) the apparent Ca(2)(+) dependence of exocytosis linearized, when assessed by progressive dihydropyridine block of Ca(2)(+) influx. Biophysical modeling of exocytosis at mature and immature AZ topographies suggests that Ca(2)(+) influx through an individual channel dominates the [Ca(2)(+)] driving exocytosis at each mature release site. We conclude that IHC synapses undergo major developmental refinements, resulting in tighter spatial coupling between Ca(2)(+) influx and exocytosis.


Subject(s)
Calcium/metabolism , Exocytosis/physiology , Hair Cells, Auditory, Inner/physiology , Models, Neurological , Spiral Ganglion/physiology , Synapses/physiology , Animals , Calcium Channels/metabolism , Calcium Signaling , Electrophysiology , Gene Expression Regulation, Developmental , Hair Cells, Auditory, Inner/cytology , Mice , Mice, Inbred C57BL , Microscopy, Confocal , Microscopy, Electron, Transmission , Mutation , Patch-Clamp Techniques , Presynaptic Terminals/ultrastructure , Spiral Ganglion/cytology , Synapses/ultrastructure
19.
Langmuir ; 34(23): 6645-6652, 2018 06 12.
Article in English | MEDLINE | ID: mdl-29739193

ABSTRACT

The bidentate aromatic adsorbate, 5-(octadecyloxy)-1,3-benzenedimethanethiol (R1ArmDT), with a specific design of extended S-S distance and a geometric constraint to resist cyclic disulfide formation was synthesized. The film formation and thermal stability of self-assembled monolayers (SAMs) derived from R1ArmDT were investigated and compared to those of SAMs derived from an analogous bidentate dithiol 2-(4-(octadecyloxy)-phenyl)propane-1,3-dithiol (R1ArDT), in which the two sulfur atoms can readily form a cyclic disulfide upon reductive elimination from the surface. Although the SAMs derived from R1ArmDT were less densely packed than those derived from R1ArDT, as judged by the data obtained by X-ray photoelectron spectroscopy and polarization modulation infrared reflection absorption spectroscopy, the SAMs derived from R1ArmDT were markedly more thermally stable than those derived from R1ArDT. The greater thermal stability of the R1ArmDT SAMs can be rationalized on the basis of the structure of the bidentate R1ArmDT headgroup, in which the two pendant sulfur atoms cannot access each other intramolecularly to form a cyclic disulfide upon reductive elimination from the surface.

20.
Heredity (Edinb) ; 120(3): 251-265, 2018 03.
Article in English | MEDLINE | ID: mdl-29238076

ABSTRACT

Spatial patterns of genetic variation can help understand how environmental factors either permit or restrict gene flow and create opportunities for regional adaptations. Organisms from harsh environments such as the Brazilian semiarid Caatinga biome may reveal how severe climate conditions may affect patterns of genetic variation. Herein we combine information from mitochondrial DNA with physical and environmental features to study the association between different aspects of the Caatinga landscape and spatial genetic variation in the whiptail lizard Ameivula ocellifera. We investigated which of the climatic, environmental, geographical and/or historical components best predict: (1) the spatial distribution of genetic diversity, and (2) the genetic differentiation among populations. We found that genetic variation in A. ocellifera has been influenced mainly by temperature variability, which modulates connectivity among populations. Past climate conditions were important for shaping current genetic diversity, suggesting a time lag in genetic responses. Population structure in A. ocellifera was best explained by both isolation by distance and isolation by resistance (main rivers). Our findings indicate that both physical and climatic features are important for explaining the observed patterns of genetic variation across the xeric Caatinga biome.


Subject(s)
Climate , Genetic Variation , Lizards/genetics , Animals , Brazil , DNA, Mitochondrial/genetics , Ecosystem , Genetics, Population , Haplotypes , Rivers
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