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1.
Surg Innov ; 31(1): 58-70, 2024 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-38059371

RESUMEN

Background: Bone cancer is a severe condition often leading to patient mortality. Diagnosis relies on X-rays, MRIs, or CT scans, which require time-consuming manual review by experts. Thus, developing an automated system is crucial for accurate classification of malignant and healthy bone.Methods: Differentiating between them poses a challenge as they may exhibit similar physical characteristics. The initial step is selecting the optimal edge detection method. Two feature sets are then generated: one with the histogram of oriented gradients (HOG) and one without. Performance evaluation involves two machine learning models: Support Vector Machine (SVM) and Random Forest.Results: Including HOG consistently yields superior results. The SVM model with HOG achieves an F-1 score of 0.92, outperforming the Random Forest model's .77. This study aims to develop reliable methods for bone cancer classification. The proposed automated method assists surgeons in accurately detecting malignant bone regions using modern image analysis techniques and machine learning models. Incorporating HOG significantly enhances performance, improving differentiation between malignant and healthy bone.Conclusion: Ultimately, this approach supports precise diagnoses and informed treatment decisions for bone cancer patients.


Asunto(s)
Neoplasias Óseas , Aprendizaje Automático , Humanos , Imagen por Resonancia Magnética , Tomografía Computarizada por Rayos X/métodos , Neoplasias Óseas/diagnóstico por imagen
2.
bioRxiv ; 2023 Jul 17.
Artículo en Inglés | MEDLINE | ID: mdl-37503047

RESUMEN

The human oral and nasal microbiota contains approximately 770 cultivable bacterial species. More than 2000 genome sequences of these bacteria can be found in the expanded Human Oral Microbiome Database (eHOMD). We developed HOMDscrape, a freely available Python software tool to programmatically retrieve and process amino acid sequences and sequence identifiers from BLAST results acquired from the eHOMD website. Using the data obtained through HOMDscrape, the phylogeny of proteins involved in bacterial flagellar motility, Type 4 pilus driven twitching motility, and Type 9 Secretion system (T9SS) driven gliding motility was constructed. A comprehensive phylogenetic analysis was conducted for all components of the rotary T9SS, a machinery responsible for secreting various enzymes, virulence factors, and enabling bacterial gliding motility. Results revealed that the T9SS outer membrane ß-barrel protein SprA of human oral microbes underwent horizontal evolution. Overall, we catalog motile microbes that inhabit the human oral microbiota and document their evolutionary connections. These results will serve as a guide for further studies exploring the impact of motility on shaping of the human oral microbiota.

3.
Cureus ; 15(6): e40041, 2023 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-37425530

RESUMEN

Clinical empathy is one of the most essential tools of medical practice, and it is an act of correctly acknowledging the emotional state of another without experiencing that state oneself. Empathy comprises four components. Mounting evidence exists to support the use of clinical empathy as a tactic for effective health care. Resolving the multi-fold barriers of clinical empathy is important. Clinical empathy is very important in the current era, and a trust-based relationship in patient care is a way to optimal clinical outcomes that can be achieved through better communication and treatment-compliance plans between health care professionals and patients.

4.
Microbiol Spectr ; 11(4): e0093723, 2023 08 17.
Artículo en Inglés | MEDLINE | ID: mdl-37358420

RESUMEN

Physical forces that arise due to bacterial motility and growth play a significant role in shaping the biogeography of the human oral microbiota. Bacteria of the genus Capnocytophaga are abundant in the human oral microbiota and yet very little is known about their physiology. The human oral isolate Capnocytophaga gingivalis exhibits robust gilding motility that is driven by the rotary type 9 secretion system (T9SS), and cells of C. gingivalis transport nonmotile oral microbes as cargo. Phages, i.e., viruses that infect bacteria, are found in abundance within the microbiota. By tracking fluorescently labeled lambda phages that do not infect C. gingivalis, we report active phage transportation by C. gingivalis swarms. Lambda phage-carrying C. gingivalis swarms were propagated near an Escherichia coli colony. The rate of disruption of the E. coli colony increased 10 times compared with a control where phages simply diffused to the E. coli colony. This finding suggests a mechanism where fluid flows produced by motile bacteria increase the rate of transport of phages to their host bacterium. Additionally, C. gingivalis swarms formed tunnel-like structures within a curli fiber-containing E. coli biofilm that increased the efficiency of phage penetration. Our data suggest that invasion by a C. gingivalis swarm changes the spatial structure of the prey biofilm and further increases the penetration of phages. IMPORTANCE Dysbiosis of the human oral microbiota is associated with several diseases, but the factors that shape the biogeography of the oral microbiota are mostly opaque. Biofilms that form in the human supragingival and subgingival regions have a diverse microbial community where some microbes form well-defined polymicrobial structures. C. gingivalis, a bacterium abundant in human gingival regions, has robust gliding motility that is powered by the type 9 secretion system. We demonstrate that swarms of C. gingivalis can transport phages through a complex biofilm which increases the death rate of the prey biofilm. These findings suggest that C. gingivalis could be used as a vehicle for the transportation of antimicrobials and that active phage transportation could shape the spatial structure of a microbial community.


Asunto(s)
Bacteriófagos , Microbiota , Humanos , Escherichia coli , Bacterias , Biopelículas
5.
Curr Diabetes Rev ; 19(8): e090123212444, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-36624650

RESUMEN

BACKGROUND AND AIM: Basal insulin combined oral therapy consisting of insulin and oral anti-diabetic drugs (OADs) is recommended for type 2 diabetes uncontrolled on OADs. There is a lack of clear evidence and recommendations on the combined use of basal insulin analogues to more than one OADs (glimepiride plus metformin) in effective control of glycemic parameters and its safety in terms of reduced hypoglycemic events, weight gain and cardiovascular risk. In this context, a group of clinical experts discussed the utility of basal insulin combined oral therapy with metformin and glimepiride in the current era. METHODS: The clinical experts discussed and provided their inputs virtually. The expert panel included clinical experts comprising endocrinologists and diabetologists from India and Nepal. RESULTS: The panel thoroughly reviewed existing literature on the subject and proposed clinical evidence and practice-based guidelines. CONCLUSION: These current clinical practice guidelines highlight the efficacy and safety of basal insulin combination therapy with various available basal insulins including neutral protamine hagedorn, detemir, glargine and degludec in addition to metformin and glimepiride therapy.


Asunto(s)
Diabetes Mellitus Tipo 2 , Hipoglucemia , Metformina , Humanos , Glucemia , Diabetes Mellitus Tipo 2/tratamiento farmacológico , Quimioterapia Combinada , Hipoglucemiantes/uso terapéutico , Insulina/uso terapéutico , Insulina de Acción Prolongada/uso terapéutico , Metformina/uso terapéutico
6.
Front Microbiol ; 13: 845563, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35620107

RESUMEN

The Fo ATP synthase, the bacterial flagellar motor, and the bacterial type 9 secretion system (T9SS) are the three known proton motive force driven biological rotary motors. In this review, we summarize the current information on the nuts and bolts of T9SS. Torque generation by T9SS, its role in gliding motility of bacteria, and the mechanism via which a T9SS-driven swarm shapes the microbiota are discussed. The knowledge gaps in our current understanding of the T9SS machinery are outlined.

7.
Artículo en Inglés | MEDLINE | ID: mdl-34909678

RESUMEN

Alzheimer's disease is a cerebrovascular disorder characterized by progressive loss of the mental capabilities. The novel therapeutic agent piracetam is a cyclic derivative of γ-aminobutyric acid and one of the oldest recognized synthetic nootropics. Piracetam improves cognitive function without stimulation or sedation. Caffeine is a central nervous system stimulant with nootropic activity. Caffeine promotes the performance of tasks that involve working memory to a limited extent, and it also retards cognitive decline in healthy individuals. The present study aimed to determine the protective effect of co-administering piracetam and caffeine on scopolamine-induced amnesia in rats. Pre-treatment with caffeine and piracetam decreased scopolamine-induced cognitive damage and amnesia. The preventive response was demonstrated by an improved learning tendency. The mechanism responsible for these effects requires further investigation. The co-administration of caffeine and piracetam has potential as a novel therapeutic strategy for combating amnesia.

8.
Physiol Mol Biol Plants ; 27(11): 2605-2619, 2021 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-34916736

RESUMEN

LncRNAs (long noncoding RNAs) are 200 bp length crucial RNA molecules, lacking coding potential and having important roles in regulating gene expression, particularly in response to abiotic stresses. In this study, we identified salt stress-induced lncRNAs in chickpea roots and predicted their intricate regulatory roles. A total of 3452 novel lncRNAs were identified to be distributed across all 08 chickpea chromosomes. On comparing salt-tolerant (ICCV 10, JG 11) and salt-sensitive cultivars (DCP 92-3, Pusa 256), 4446 differentially expressed lncRNAs were detected under various salt  treatments. We predicted 3373 lncRNAs to be regulating their target genes in cis regulating manner and 80 unique lncRNAs were observed as interacting with 136 different miRNAs, as eTMs (endogenous target mimic) targets of miRNAs and implicated them in the regulatory network of salt stress response. Functional analysis of these lncRNA revealed their association in targeting salt stress response-related genes like potassium transporter, transporter family genes, serine/threonine-protein kinase, aquaporins like TIP1-2, PIP2-5 and transcription factors like, AP2, NAC, bZIP, ERF, MYB and WRKY. Furthermore, about 614 lncRNA-SSRs (simple sequence repeats) were identified as a new generation of molecular markers with higher efficiency and specificity in chickpea. Overall, these findings will pave the understanding of comprehensive functional role of potential lncRNAs, which can help in providing insight into the molecular mechanism of salt tolerance in chickpea. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s12298-021-01093-0.

9.
Sci Adv ; 6(10): eaay6616, 2020 03.
Artículo en Inglés | MEDLINE | ID: mdl-32181348

RESUMEN

The gliding bacterium Flavobacterium johnsoniae is known to have an adhesin, SprB, that moves along the cell surface on a spiral track. Following viscous shear, cells can be tethered by the addition of an anti-SprB antibody, causing spinning at 3 Hz. Labeling the type 9 secretion system (T9SS) with a YFP fusion of GldL showed a yellow fluorescent spot near the rotation axis, indicating that the motor driving the motion is associated with the T9SS. The distance between the rotation axis and the track (90 nm) was determined after adding a Cy3 label for SprB. A rotary motor spinning a pinion of radius 90 nm at 3 Hz would cause a spot on its periphery to move at 1.5 µm/s, the gliding speed. We suggest the pinion drives a flexible tread that carries SprB along a track fixed to the cell surface. Cells glide when this adhesin adheres to the solid substratum.


Asunto(s)
Adhesinas Bacterianas/genética , Sistemas de Secreción Bacterianos/genética , Flavobacterium/genética , Adhesinas Bacterianas/metabolismo , Anticuerpos Antibacterianos/química , Adhesión Bacteriana/fisiología , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Sistemas de Secreción Bacterianos/metabolismo , Fenómenos Biomecánicos , Carbocianinas/química , Flavobacterium/metabolismo , Colorantes Fluorescentes/química , Expresión Génica , Genes Reporteros , Locomoción/fisiología , Proteínas Luminiscentes/genética , Proteínas Luminiscentes/metabolismo , Unión Proteica , Proteínas Recombinantes de Fusión/genética , Proteínas Recombinantes de Fusión/metabolismo , Rotación
10.
IEEE Trans Cybern ; 49(10): 3677-3688, 2019 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-29994696

RESUMEN

Finding low-dimensional representation of high-dimensional data sets is an important task in various applications. The fact that data sets often contain clusters embedded in different subspaces poses barrier to this task. Driven by the need in methods that enable clustering and finding each cluster's intrinsic subspace simultaneously, in this paper, we propose a regularized Gaussian mixture model (GMM) for clustering. Despite the advantages of GMM, such as its probabilistic interpretation and robustness against observation noise, traditional maximum-likelihood estimation for GMMs shows disappointing performance in high-dimensional setting. The proposed regularization method finds low-dimensional representations of the component covariance matrices, resulting in better estimation of local feature correlations. The regularization problem can be incorporated in the expectation maximization algorithm for maximizing the likelihood function of a GMM, with the M -step modified to incorporate the regularization. The M -step involves a determinant maximization problem, which can be solved efficiently. The performance of the proposed method is demonstrated using several simulated data sets. We also illustrate the potential value of the proposed method in applications using four real data sets.

11.
Int J Med Mushrooms ; 21(11): 1123-1136, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-32450022

RESUMEN

The present study evaluates the antiarthritic effect of hydroethanolic extract of Pleurotus ostreatus cv. Florida, which was tested against adjuvant induced arthritis in rat models. Arthritis was induced by administration of complete Freund's adjuvant into the subplantar surface of left paw of rats. The extract was given orally at doses 200 mg/ kg and 400 mg/kg and piroxicam was administered intraperitonially (4 mg/kg). In vitro testing on parameters including antiproteinestrase, albumin denaturation and heat induce hemolysis was also carried out. There was significant decrease (p < 0.001) in proteinase activity and membrane stabilization in vivo studies on cv. Florida extract treated rats showed a significant (p < 0.001) decrease in paw volume, joint diameter, and spontaneous change in body weight recorded for 21 days. The treatment also resulted in an increase in rats' gripping activity compared with arthritic control rats. X-ray examinations showed a decrease in joint swelling. Histopathological examination of the extract treated group showed a significant decrease in joint space. There was also an increase in antibody levels. The antioxidant parameters showed a significant (p < 0.001) increase in superoxide dismutase and catalase enzymatic activities. Thus P. ostreatus cv. Florida extract demonstrates a potent antioxidant activity in a rat model. It is concluded that the P. ostreatus cv. Florida extract contains medicinally important constituents that show antiarthritic activity in rats.


Asunto(s)
Antiinflamatorios/administración & dosificación , Artritis/terapia , Terapia Biológica/métodos , Mezclas Complejas/administración & dosificación , Pleurotus/química , Adyuvantes Inmunológicos/administración & dosificación , Administración Oral , Animales , Antiinflamatorios/aislamiento & purificación , Artritis/inducido químicamente , Artritis/patología , Peso Corporal , Mezclas Complejas/aislamiento & purificación , Modelos Animales de Enfermedad , Adyuvante de Freund/administración & dosificación , Histocitoquímica , Inyecciones Intraperitoneales , Piroxicam/administración & dosificación , Ratas , Resultado del Tratamiento
12.
Proc Natl Acad Sci U S A ; 115(34): 8633-8638, 2018 08 21.
Artículo en Inglés | MEDLINE | ID: mdl-30082394

RESUMEN

The human microbiome is an assemblage of diverse bacteria that interact with one another to form communities. Bacteria in a given community are arranged in a 3D matrix with many degrees of freedom. Snapshots of the community display well-defined structures, but the steps required for their assembly are not understood. Here, we show that this construction is carried out with the help of gliding bacteria. Gliding is defined as the motion of cells over a solid or semisolid surface without the necessity of growth or the aid of pili or flagella. Genomic analysis suggests that gliding bacteria are present in human microbial communities. We focus on Capnocytophaga gingivalis, which is present in abundance in the human oral microbiome. Tracking of fluorescently labeled single cells and of gas bubbles carried by fluid flow shows that swarms of C. gingivalis are layered, with cells in the upper layers moving more rapidly than those in the lower layers. Thus, cells also glide on top of one another. Cells of nonmotile bacterial species attach to the surface of C. gingivalis and are propelled as cargo. The cargo cell moves along the length of a C. gingivalis cell, looping from one pole to the other. Multicolor fluorescent spectral imaging of cells of different live but nonmotile bacterial species reveals their long-range transport in a polymicrobial community. A swarm of C. gingivalis transports some nonmotile bacterial species more efficiently than others and helps to shape the spatial organization of a polymicrobial community.


Asunto(s)
Capnocytophaga/fisiología , Consorcios Microbianos/fisiología , Microbiota/fisiología , Boca/microbiología , Humanos
13.
J Bacteriol ; 200(2)2018 01 15.
Artículo en Inglés | MEDLINE | ID: mdl-29109184

RESUMEN

Flavobacterium johnsoniae exhibits rapid gliding motility over surfaces. At least 20 genes are involved in this process. Seven of these, gldK, gldL, gldM, gldN, sprA, sprE, and sprT, encode proteins of the type IX protein secretion system (T9SS). The T9SS is required for surface localization of the motility adhesins SprB and RemA, and for secretion of the soluble chitinase ChiA. Here, we demonstrate that the gliding motility proteins GldA, GldB, GldD, GldF, GldH, GldI, and GldJ are also essential for secretion. Cells with mutations in the genes encoding any of these seven proteins had normal levels of gldK mRNA but dramatically reduced levels of the GldK protein, which may explain the secretion defects of the motility mutants. GldJ is necessary for stable accumulation of GldK, and each mutant lacked the GldJ protein. F. johnsoniae cells that produced truncated GldJ, lacking eight to 13 amino acids from the C terminus, accumulated GldK but were deficient in gliding motility. SprB was secreted by these cells but was not propelled along their surfaces. This C-terminal region of GldJ is thus required for gliding motility but not for secretion. The identification of mutants that are defective for motility but competent for secretion begins to untangle the F. johnsoniae gliding motility machinery from the T9SS.IMPORTANCE Many members of the phylum Bacteroidetes secrete proteins using T9SSs. T9SSs appear to be confined to members of this phylum. Many of these bacteria also glide rapidly over surfaces using a motility machine that is also confined to the Bacteroidetes and appears to be intertwined with the T9SS. This study identifies F. johnsoniae proteins that are required for both T9SS function and gliding motility. It also provides an explanation for the link between secretion and gliding and identifies mutants with defects in motility but not secretion.


Asunto(s)
Proteínas Bacterianas/metabolismo , Sistemas de Secreción Bacterianos/fisiología , Flavobacterium/genética , Flavobacterium/fisiología , Adhesinas Bacterianas/metabolismo , Sistemas de Secreción Bacterianos/genética , Bacteroidetes/fisiología , Quitinasas/metabolismo , Regulación Bacteriana de la Expresión Génica , Locomoción , Transporte de Proteínas
14.
J Alzheimers Dis ; 57(4): 1017-1039, 2017.
Artículo en Inglés | MEDLINE | ID: mdl-27662312

RESUMEN

The communication between neurons at synaptic junctions is an intriguing process that monitors the transmission of various electro-chemical signals in the central nervous system. Albeit any aberration in the mechanisms associated with transmission of these signals leads to loss of synaptic contacts in both the neocortex and hippocampus thereby causing insidious cognitive decline and memory dysfunction. Compelling evidence suggests that soluble amyloid-ß (Aß) and hyperphosphorylated tau serve as toxins in the dysfunction of synaptic plasticity and aberrant neurotransmitter (NT) release at synapses consequently causing a cognitive decline in Alzheimer's disease (AD). Further, an imbalance between excitatory and inhibitory neurotransmission systems induced by impaired redox signaling and altered mitochondrial integrity is also amenable for such abnormalities. Defective NT release at the synaptic junction causes several detrimental effects associated with altered activity of synaptic proteins, transcription factors, Ca2+ homeostasis, and other molecules critical for neuronal plasticity. These detrimental effects further disrupt the normal homeostasis of neuronal cells and thereby causing synaptic loss. Moreover, the precise mechanistic role played by impaired NTs and neuromodulators (NMs) and altered redox signaling in synaptic dysfunction remains mysterious, and their possible interlink still needs to be investigated. Therefore, this review elucidates the intricate role played by both defective NTs/NMs and altered redox signaling in synaptopathy. Further, the involvement of numerous pharmacological approaches to compensate neurotransmission imbalance has also been discussed, which may be considered as a potential therapeutic approach in synaptopathy associated with AD.


Asunto(s)
Enfermedad de Alzheimer/metabolismo , Neurotransmisores/metabolismo , Estrés Psicológico/metabolismo , Sinapsis/metabolismo , Transmisión Sináptica/fisiología , Animales , Humanos
15.
Biophys J ; 111(5): 1008-13, 2016 Sep 06.
Artículo en Inglés | MEDLINE | ID: mdl-27602728

RESUMEN

Flavobacterium johnsoniae, a rod-shaped bacterium, glides over surfaces at speeds of ∼2 µm/s. The propulsion of a cell-surface adhesin, SprB, is known to enable gliding. We used cephalexin to generate elongated cells with irregular shapes and followed their displacement in three dimensions. These cells rolled about their long axes as they moved forward, following a right-handed trajectory. We coated gold nanoparticles with an SprB antibody and tracked them in three dimensions in an evanescent field where the nanoparticles appeared brighter when they were closer to the glass. The nanoparticles followed a right-handed spiral trajectory on the surface of the cell. Thus, if SprB were to adhere to the glass rather than to a nanoparticle, the cell would move forward along a right-handed trajectory, as observed, but in a direction opposite to that of the nanoparticle.


Asunto(s)
Adhesinas Bacterianas/metabolismo , Flavobacterium/fisiología , Movimiento/fisiología , Antibacterianos , Anticuerpos Antibacterianos , Cefalexina , Vidrio , Oro , Nanopartículas del Metal , Microscopía , Movimiento (Física)
16.
Nat Phys ; 12(2): 175-178, 2016 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-27499800

RESUMEN

Caulobacter crescentus, a monotrichous bacterium, swims by rotating a single right-handed helical filament. CW motor rotation thrusts the cell forward 1, a mode of motility known as the pusher mode; CCW motor rotation pulls the cell backward, a mode of motility referred to as the puller mode 2. The situation is opposite in E. coli, a peritrichous bacterium, where CCW rotation of multiple left-handed filaments drives the cell forward. The flagellar motor in E. coli generates more torque in the CCW direction than the CW direction in swimming cells 3,4. However, monotrichous bacteria including C. crescentus swim forward and backward at similar speeds, prompting the assumption that motor torques in the two modes are the same 5,6. Here, we present evidence that motors in C. crescentus develop higher torques in the puller mode than in the pusher mode, and suggest that the anisotropy in torque-generation is similar in two species, despite the differences in filament handedness and motor bias (probability of CW rotation).

17.
Sci Adv ; 1(9): e1500299, 2015 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-26601280

RESUMEN

Stimulation of Escherichia coli by exponential ramps of chemoattractants generates step changes in the concentration of the response regulator, CheY-P. Because flagellar motors are ultrasensitive, this should change the fraction of time that motors spin clockwise, the CWbias. However, early work failed to show changes in CWbias when ramps were shallow. This was explained by a model for motor remodeling that predicted plateaus in plots of CWbias versus [CheY-P]. We looked for these plateaus by examining distributions of CWbias in populations of cells with different mean [CheY-P]. We did not find such plateaus. Hence, we repeated the work on shallow ramps and found that motors did indeed respond. These responses were quantitatively described by combining motor remodeling with ultrasensitivity in a model that exhibited high sensitivities over a wide dynamic range.

18.
Curr Opin Microbiol ; 28: 93-7, 2015 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-26476806

RESUMEN

Cells of Flavobacterium johnsoniae, a rod-shaped bacterium about 6 µm long, do not have flagella or pili, yet they move over surfaces at speeds of about 2 µm/s. This motion is called gliding. Recent advances in F. johnsoniae research include the discovery of mobile cell-surface adhesins and rotary motors. The puzzle is how rotary motion leads to linear motion. We suggest a possible mechanism, inspired by the snowmobile.


Asunto(s)
Adhesinas Bacterianas/metabolismo , Proteínas Bacterianas/fisiología , Flavobacterium/fisiología , Locomoción , Modelos Biológicos , Vehículos a Motor Todoterreno
19.
Curr Biol ; 25(3): 338-341, 2015 Feb 02.
Artículo en Inglés | MEDLINE | ID: mdl-25619763

RESUMEN

Cells of Flavobacterium johnsoniae, a rod-shaped bacterium devoid of pili or flagella, glide over glass at speeds of 2-4 µm/s [1]. Gliding is powered by a protonmotive force [2], but the machinery required for this motion is not known. Usually, cells move along straight paths, but sometimes they exhibit a reciprocal motion, attach near one pole and flip end over end, or rotate. This behavior is similar to that of a Cytophaga species described earlier [3]. Development of genetic tools for F. johnsoniae led to discovery of proteins involved in gliding [4]. These include the surface adhesin SprB that forms filaments about 160 nm long by 6 nm in diameter, which, when labeled with a fluorescent antibody [2] or a latex bead [5], are seen to move longitudinally down the length of a cell, occasionally shifting positions to the right or the left. Evidently, interaction of these filaments with a surface produces gliding. To learn more about the gliding motor, we sheared cells to reduce the number and size of SprB filaments and tethered cells to glass by adding anti-SprB antibody. Cells spun about fixed points, mostly counterclockwise, rotating at speeds of 1 Hz or more. The torques required to sustain such speeds were large, comparable to those generated by the flagellar rotary motor. However, we found that a gliding motor runs at constant speed rather than at constant torque. Now, there are three rotary motors powered by protonmotive force: the bacterial flagellar motor, the Fo ATP synthase, and the gliding motor.


Asunto(s)
Adhesinas Bacterianas/metabolismo , Flavobacterium/fisiología , Proteínas Motoras Moleculares/fisiología , Actividad Motora/fisiología , Fuerza Protón-Motriz/fisiología , Fenómenos Biomecánicos , Microscopía de Contraste de Fase , Microesferas , Rotación , Torque
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