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1.
Nature ; 575(7784): 602-603, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31768038
2.
BMC Complement Altern Med ; 19(1): 331, 2019 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-31752812

RESUMO

BACKGROUND: Zingiber zerumbet rhizome and its bioactive metabolites have previously been reported to exhibit innumerable pharmacological properties particularly anti-inflammatory activities. In the present study, the 80% ethanol extract, essential oil and zerumbone of Z. zerumbet rhizomes were explored for their in vitro immunosuppressive properties on chemotaxis, CD11b/CD18 expression, phagocytosis and chemiluminescence of isolated human polymorphonuclear neutrophils (PMNs). METHODS: The extract was analyzed quantitatively by performing a validated reversed phase high performance liquid chromatography (RP-HPLC). Zerumbone was isolated by chromatographic technique while the essential oil was acquired through hydro-distillation of the rhizomes and further analyzed by gas chromatography (GC) and GC-MS. Chemotaxis assay was assessed by using a 24-well cell migration assay kit, while CD18 integrin expression and phagocytic engulfment were measured using flow cytometry. The reactive oxygen species (ROS) production was evaluated by applying lucigenin- and luminol-enhanced chemiluminescence assays. RESULTS: Zerumbone was found to be the most abundant compound in the extract (242.73 mg/g) and the oil (58.44%). Among the samples tested, the oil revealed the highest inhibition on cell migration with an IC50 value of 3.24 µg/mL. The extract, oil and zerumbone showed moderate inhibition of CD18 integrin expression in a dose-dependent trend. Z. zerumbet extract showed the highest inhibitory effect on phagocytic engulfment with percentage of phagocytizing cells of 55.43% for PMN. Zerumbone exhibited strong inhibitory activity on oxidative burst of zymosan- and PMA-stimulated neutrophils. Zerumbone remarkably inhibited extracellular ROS production in PMNs with an IC50 value of 17.36 µM which was comparable to that of aspirin. CONCLUSION: The strong inhibition on the phagocytosis of neutrophils by Z. zerumbet extract and its essential oil might be due the presence of its chemical components particularly zerumbone which was capable of impeding phagocytosis at different stages.


Assuntos
Imunossupressores/farmacologia , Neutrófilos/efeitos dos fármacos , Óleos Voláteis/farmacologia , Fagocitose/efeitos dos fármacos , Sesquiterpenos/farmacologia , Zingiberaceae/química , Sobrevivência Celular , Células Cultivadas , Quimiotaxia/efeitos dos fármacos , Humanos , Extratos Vegetais/farmacologia
3.
Adv Exp Med Biol ; 1146: 79-103, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31612455

RESUMO

The last 20 years have seen the blooming of microfluidics technologies applied to biological sciences. Microfluidics provides effective tools for biological analysis, allowing the experimentalists to extend their playground to single cells and single molecules, with high throughput and resolution which were inconceivable few decades ago. In particular, microfluidic devices are profoundly changing the conventional way of studying the cell motility and cell migratory dynamics. In this chapter we will furnish a comprehensive view of the advancements made in the research domain of confinement-induced cell migration, thanks to the use of microfluidic devices. The chapter is subdivided in three parts. Each section will be addressing one of the fundamental questions that the microfluidic technology is contributing to unravel: (i) where cell migration takes place, (ii) why cells migrate and, (iii) how the cells migrate. The first introductory part is devoted to a thumbnail, and partially historical, description of microfluidics and its impact in biological sciences. Stress will be put on two aspects of the devices fabrication process, which are crucial for biological applications: materials used and coating methods. The second paragraph concerns the cell migration induced by environmental cues: chemical, leading to chemotaxis, mechanical, at the basis of mechanotaxis, and electrical, which induces electrotaxis. Each of them will be addressed separately, highlighting the fundamental role of microfluidics in providing the well-controlled experimental conditions where cell migration can be induced, investigated and ultimately understood. The third part of the chapter is entirely dedicated to how the cells move in confined environments. Invadosomes (the joint name for podosomes and invadopodia) are cell protrusion that contribute actively to cell migration or invasion. The formation of invadosomes under confinement is a research topic that only recently has caught the attention of the scientific community: microfluidic design is helping shaping the future direction of this emerging field of research.


Assuntos
Movimento Celular , Microfluídica , Podossomos , Animais , Quimiotaxia , Humanos , Dispositivos Lab-On-A-Chip , Microfluídica/instrumentação , Podossomos/metabolismo , Pesquisa/tendências
4.
Nature ; 574(7776): 57-62, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31534221

RESUMO

The causative agent of plague, Yersinia pestis, uses a type III secretion system to selectively destroy immune cells in humans, thus enabling Y. pestis to reproduce in the bloodstream and be transmitted to new hosts through fleabites. The host factors that are responsible for the selective destruction of immune cells by plague bacteria are unknown. Here we show that LcrV, the needle cap protein of the Y. pestis type III secretion system, binds to the N-formylpeptide receptor (FPR1) on human immune cells to promote the translocation of bacterial effectors. Plague infection in mice is characterized by high mortality; however, Fpr1-deficient mice have increased survival and antibody responses that are protective against plague. We identified FPR1R190W as a candidate resistance allele in humans that protects neutrophils from destruction by the Y. pestis type III secretion system. Thus, FPR1 is a plague receptor on immune cells in both humans and mice, and its absence or mutation provides protection against Y. pestis. Furthermore, plague selection of FPR1 alleles appears to have shaped human immune responses towards other infectious diseases and malignant neoplasms.


Assuntos
Macrófagos/metabolismo , Neutrófilos/metabolismo , Peste/microbiologia , Receptores de Formil Peptídeo/metabolismo , Yersinia pestis/metabolismo , Alelos , Animais , Antígenos de Bactérias/metabolismo , Aderência Bacteriana , Sistemas CRISPR-Cas , Quimiotaxia/imunologia , Modelos Animais de Doenças , Feminino , Células HEK293 , Humanos , Macrófagos/citologia , Macrófagos/imunologia , Macrófagos/microbiologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Neutrófilos/citologia , Neutrófilos/imunologia , Neutrófilos/microbiologia , Peste/imunologia , Peste/prevenção & controle , Polimorfismo de Nucleotídeo Único/genética , Proteínas Citotóxicas Formadoras de Poros/metabolismo , Receptores de Formil Peptídeo/antagonistas & inibidores , Receptores de Formil Peptídeo/deficiência , Receptores de Formil Peptídeo/genética , Sistemas de Secreção Tipo III/efeitos dos fármacos , Células U937 , Yersinia pestis/química , Yersinia pestis/imunologia , Yersinia pestis/patogenicidade
5.
J Dairy Sci ; 102(11): 10316-10328, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31495609

RESUMO

To evaluate the effect of recombinant bovine interleukin-8 (rbIL-8) on uterine health and milk production, 2 separate studies were conducted. For study 1, postpartum Holstein cows (n = 213) were randomly allocated into 1 of 3 intrauterine treatment groups: control (CTR, 250 mL of saline solution), low dose (L-IL8, 11.25 µg of rbIL-8 diluted in 250 mL of saline solution), and high dose (H-IL8, 1,125 µg of rbIL-8 diluted in 250 mL of saline solution). Intrauterine delivery of treatments was performed within 12 h of parturition. Cows were evaluated for retained fetal membranes, puerperal metritis, and clinical endometritis. Blood samples were collected immediately before treatment and 1, 2, and 3 d in milk for assessment of IL-8, haptoglobin, fatty acids, and ß-hydroxybutyrate concentrations. Treatment with rbIL-8 reduced the incidence of puerperal metritis in multiparous cows (CTR = 34.3, L-IL8 = 8.11, and H-IL8 = 6.35%). Both the L-IL8 and H-IL8 groups produced significantly more milk, fat-corrected milk, and energy-corrected milk yields when compared with placebo-treated controls. A second study was performed to confirm the effect of rbIL-8 on milk production. In study 2, 164 primiparous cows were randomly allocated into 1 of 4 treatment groups: control (CTR, 250 mL of saline solution), low dose (L-IL8, 0.14 µg of rbIL-8), medium dose (M-IL8, 14 µg of rbIL-8), and high dose (H-IL8, 1,400 µg of rbIL-8). Treatments were prepared and administered as described for study 1. Cows in the L-IL8, M-IL8, and H-IL8 groups produced significantly more milk, fat-corrected milk, and energy-corrected milk yields when compared with control cows. In conclusion, treatment with rbIL-8 decreased the incidence of puerperal metritis in multiparous cows. The administration of rbIL-8 was repeatedly associated with a dramatic and long-lasting improvement of lactation performance.


Assuntos
Doenças dos Bovinos/prevenção & controle , Bovinos/fisiologia , Interleucina-8/farmacologia , Cetose/veterinária , Lactação/efeitos dos fármacos , Ácido 3-Hidroxibutírico/sangue , Animais , Bovinos/imunologia , Bovinos/metabolismo , Doenças dos Bovinos/metabolismo , Doenças dos Bovinos/fisiopatologia , Quimiotaxia , Endometrite/prevenção & controle , Endometrite/veterinária , Feminino , Fermentação , Haptoglobinas/metabolismo , Nível de Saúde , Interleucina-8/administração & dosagem , Interleucina-8/sangue , Interleucina-8/genética , Cetose/metabolismo , Cetose/fisiopatologia , Cetose/prevenção & controle , Leite/química , Paridade , Parto , Placenta Retida/prevenção & controle , Placenta Retida/veterinária , Período Pós-Parto , Gravidez , Proteínas Recombinantes/administração & dosagem , Proteínas Recombinantes/sangue , Proteínas Recombinantes/genética , Proteínas Recombinantes/farmacologia
6.
Infect Immun ; 87(11)2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31481407

RESUMO

Periodontal disease is a significant health burden, causing tooth loss and poor oral and overall systemic health. Dysbiosis of the oral biofilm and a dysfunctional immune response drive chronic inflammation, causing destruction of soft tissue and alveolar bone supporting the teeth. Treponema denticola, a spirochete abundant in the plaque biofilm of patients with severe periodontal disease, perturbs neutrophil function by modulating appropriate phosphoinositide (PIP) signaling. Through a series of immunoblotting and quantitative PCR (qPCR) experiments, we show that Msp does not alter the gene transcription or protein content of key enzymes responsible for PIP3 signaling: 3' phosphatase and tensin homolog (PTEN), phosphatidylinositol 3-kinase (PI3K), or 5' Src homology 2 domain-containing inositol phosphatase 1 (SHIP1). Instead, using immunoblotting and enzyme-linked immunosorbent assays (ELISAs), we found that Msp activates PTEN through dephosphorylation specifically at the S380 site. Msp in intact organisms or outer membrane vesicles also restricts PIP signaling. SHIP1 phosphatase release was assessed using chemical inhibition and immunoprecipitation to show that Msp moderately decreases SHIP1 activity. Msp also prevents secondary activation of the PTEN/PI3K response. We speculate that this result is due to the redirection of the PIP3 substrate away from SHIP1 to PTEN. Immunofluorescence microscopy revealed a redistribution of PTEN from the cytoplasm to the plasma membrane following exposure to Msp, which may contribute to PTEN activation. Mechanisms of how T. denticola modulates and evades the host immune response are still poorly described, and here we provide further mechanistic evidence of how spirochetes modify PIP signaling to dampen neutrophil function. Understanding how oral bacteria evade the immune response to perpetuate the cycle of inflammation and infection is critical for combating periodontal disease to improve overall health outcomes.


Assuntos
Proteínas de Bactérias/farmacologia , Neutrófilos/efeitos dos fármacos , Fosfatidilinositóis/metabolismo , Porinas/farmacologia , Treponema denticola/metabolismo , Animais , Proteínas de Bactérias/metabolismo , Quimiotaxia , Regulação da Expressão Gênica/efeitos dos fármacos , Imunoprecipitação , Masculino , Camundongos , Camundongos Endogâmicos C57BL , PTEN Fosfo-Hidrolase/genética , PTEN Fosfo-Hidrolase/metabolismo , Fosfatidilinositol 3-Quinase/metabolismo , Fosfatidilinositol-3,4,5-Trifosfato 5-Fosfatases/genética , Fosfatidilinositol-3,4,5-Trifosfato 5-Fosfatases/metabolismo , Porinas/metabolismo
7.
Mol Cells ; 42(8): 589-596, 2019 Aug 31.
Artigo em Inglês | MEDLINE | ID: mdl-31402636

RESUMO

ßPix is a guanine nucleotide exchange factor for the Rho family small GTPases, Rac1 and Cdc42. It is known to regulate focal adhesion dynamics and cell migration. However, the in vivo role of ßPix is currently not well understood. Here, we report the production and characterization of ßPix-KO mice. Loss of ßPix results in embryonic lethality accompanied by abnormal developmental features, such as incomplete neural tube closure, impaired axial rotation, and failure of allantoischorion fusion. We also generated ßPix-KO mouse embryonic fibroblasts (MEFs) to examine ßPix function in mouse fibroblasts. ßPix-KO MEFs exhibit decreased Rac1 activity, and defects in cell spreading and platelet-derived growth factor (PDGF)-induced ruffle formation and chemotaxis. The average size of focal adhesions is increased in ßPix-KO MEFs. Interestingly, ßPix-KO MEFs showed increased motility in random migration and rapid wound healing with elevated levels of MLC2 phosphorylation. Taken together, our data demonstrate that ßPix plays essential roles in early embryonic development, cell spreading, and cell migration in fibroblasts.


Assuntos
Movimento Celular/efeitos dos fármacos , Quimiotaxia/efeitos dos fármacos , Embrião de Mamíferos/citologia , Desenvolvimento Embrionário/efeitos dos fármacos , Fibroblastos/citologia , Fator de Crescimento Derivado de Plaquetas/farmacologia , Fatores de Troca de Nucleotídeo Guanina Rho/metabolismo , Animais , Bovinos , Perda do Embrião/patologia , Fibroblastos/efeitos dos fármacos , Fibroblastos/metabolismo , Adesões Focais/metabolismo , Humanos , Camundongos Knockout , Cadeias Leves de Miosina/metabolismo , Fosforilação/efeitos dos fármacos , Fosfosserina/metabolismo
8.
Nat Commun ; 10(1): 3692, 2019 08 13.
Artigo em Inglês | MEDLINE | ID: mdl-31409788

RESUMO

Rational choice theory assumes optimality in decision-making. Violations of a basic axiom of economic rationality known as "Independence of Irrelevant Alternatives" (IIA) have been demonstrated in both humans and animals and could stem from common neuronal constraints. Here we develop tests for IIA in the nematode Caenorhabditis elegans, an animal with only 302 neurons, using olfactory chemotaxis assays. We find that in most cases C. elegans make rational decisions. However, by probing multiple neuronal architectures using various choice sets, we show that violations of rationality arise when the circuit of olfactory sensory neurons is asymmetric. We further show that genetic manipulations of the asymmetry between the AWC neurons can make the worm irrational. Last, a context-dependent normalization-based model of value coding and gain control explains how particular neuronal constraints on information coding give rise to irrationality. Thus, we demonstrate that bounded rationality could arise due to basic neuronal constraints.


Assuntos
Caenorhabditis elegans/fisiologia , Animais , Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/metabolismo , Quimiotaxia , Neurônios Receptores Olfatórios/fisiologia , Olfato
9.
Radiat Res ; 192(4): 440-450, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31393823

RESUMO

Radiotherapy to treat brain tumors can potentially harm the central nervous system (CNS). The radiation stimulates a series of immune responses in both the CNS as well as peripheral immune system. To date, studies have mostly focused on the changes occurring in the immune response within the CNS. In this study, we investigated the effect of γ-ray-induced CNS injury on the peripheral immune response using a cell co-culture model and a whole-brain irradiation (WBI) rat model. Nerve cells (SH-SY5Y and U87 MG cells) were γ-ray irradiated, then culture media of the irradiated cells (conditioned media) was used to culture immune cells (THP-1 cells or Jurkat cells). Analyses were performed based on the response of immune cells in conditioned media. Sprague-Dawley rats received WBI at different doses, and were fed for one week to one month postirradiation. Spleen and peripheral blood were then isolated and analyzed. We observed that the number of monocytes in peripheral blood, and the level of NK cells and NKT cells in spleen increased after CNS injury. However, the level of T cells in spleen did not change and the level of B cells in the spleen decreased after γ-ray-induced CNS injury. These findings indicate that CNS injury caused by ionizing radiation induces a series of changes in the peripheral immune system.


Assuntos
Sistema Nervoso Central/lesões , Sistema Nervoso Central/efeitos da radiação , Raios gama/efeitos adversos , Lesões Experimentais por Radiação/imunologia , Animais , Diferenciação Celular/efeitos da radiação , Linhagem Celular Tumoral , Sistema Nervoso Central/patologia , Quimiocinas/sangue , Quimiotaxia/efeitos da radiação , Humanos , Imunidade Inata/efeitos da radiação , Masculino , Lesões Experimentais por Radiação/sangue , Lesões Experimentais por Radiação/patologia , Ratos , Ratos Sprague-Dawley , Irradiação Corporal Total/efeitos adversos
10.
Soft Matter ; 15(35): 7071-7079, 2019 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-31441486

RESUMO

Motile bacteria are often found in complex, polymer-rich environments in which microbes can aggregate via polymer-induced depletion forces. Bacterial aggregation has many biological implications; it can promote biofilm formation, upregulate virulence factors, and lead to quorum sensing. The steady state aggregation behavior of motile bacteria in polymer solutions has been well studied and shows that stronger depletion forces are required to aggregate motile bacteria as compared with their nonmotile analogs. However, no one has studied whether these same trends hold at the initial stages of aggregation. We use experiments and numerical calculations to investigate the polymer-induced depletion aggregation of motile Escherichia coli in polyethylene glycol solutions on short experimental timescales (∼10 min). Our work reveals that in the semi-dilute polymer concentration regime and at short timescales, in contrast to what is found at steady state, bacterial motility actually enhances aggregate formation by increasing the collision rate in viscous environments. These unexpected findings have implications for developing models of active matter, and for understanding bacterial aggregation in dynamic, biological environments, where the system may never reach steady state.


Assuntos
Movimento Celular , Quimiotaxia , Escherichia coli/fisiologia , Polietilenoglicóis/metabolismo , Polímeros/metabolismo , Percepção de Quorum , Biofilmes , Polietilenoglicóis/química , Polímeros/química
11.
Insect Biochem Mol Biol ; 113: 103213, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31442487

RESUMO

Mosquitoes rely heavily on the olfactory system to find a host for a bloodmeal, plants for a source of energy and suitable sites for oviposition. Here, we examined a cluster of eight odorant receptors (ORs), which includes one OR, CquiOR1, previously identified to be sensitive to plant-derived compounds. We cloned 5 ORs from Culex quinquefasciatus and two ORs from Aedes aegypti, ie, CquiOR2, CquiOR4, CquiOR5, CquiOR84, CquiOR85, AaegOR14, and AaegOR15 and then deorphanized these receptors using the Xenopus oocyte recording system and a large panel of odorants. 2-Phenylethanol, phenethyl formate, and phenethyl propionate were the best ligands for CquiOR4 somewhat resembling the profile of AaegOR15, which gave the strongest responses to phenethyl propionate, phenethyl formate, and acetophenone. In contrast, the best ligands for CquiOR5 were linalool, PMD, and linalool oxide. CquiOR4 was predominantly expressed in antennae of nonblood fed female mosquitoes, with transcript levels significantly reduced after a blood meal. 2-Phenylethanol showed repellency activity comparable to that of DEET at 1%. RNAi experiments suggest that at least in part 2-phenylethanol-elicited repellency is mediated by CquiOR4 activation.


Assuntos
Aedes/fisiologia , Culex/fisiologia , Flores/química , Proteínas de Insetos/genética , Odorantes/análise , Receptores Odorantes/genética , Aedes/genética , Animais , Quimiotaxia , Culex/genética , Feminino , Proteínas de Insetos/metabolismo , Repelentes de Insetos/farmacologia , Receptores Odorantes/metabolismo , Especificidade da Espécie
12.
PLoS Negl Trop Dis ; 13(8): e0007573, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31408466

RESUMO

The metacercariae of the Clonorchis sinensis liver fluke excyst in the duodenum of mammalian hosts, and the newly excysted juveniles (CsNEJs) migrate along the bile duct via bile chemotaxis. Cholic acid is a major component of bile that induces this migration. We investigated the neuronal control of chemotactic behavior of CsNEJs toward cholic acid. The migration of CsNEJs was strongly inhibited at sub-micromolar concentration by dopamine D1 (LE-300 and SKF-83566), D2 (spiramide, nemonapride, and sulpiride), and D3 (GR-103691 and NGB-2904) receptor antagonists, as well as a dopamine reuptake inhibitor (BTCP). Neuropeptides, FMRFamide, peptide YY, and neuropeptide Y were also potent inhibitors of chemotaxis. Meanwhile, serotonergic, glutamatergic, and cholinergic inhibitors did not affect chemotaxis, with the exception of fluoxetine and CNQX. Confocal immunofluorescence analysis indicated that dopaminergic and cholinergic neurons were colocalized in the somatic muscle tissues of adult C. sinensis. Our findings suggest that dopaminergic neurons and neuropeptides play a major role in the chemotactic migration of CsNEJs to bile, and their inhibitors or modulators could be utilized to prevent their migration from the bile duct.


Assuntos
Quimiotaxia/efeitos dos fármacos , Quimiotaxia/fisiologia , Clonorchis sinensis/efeitos dos fármacos , Clonorchis sinensis/fisiologia , Fasciola hepatica/efeitos dos fármacos , Neurotransmissores/farmacologia , Animais , Benzamidas/farmacologia , Compostos de Bifenilo/farmacologia , Ácido Cólico , Dopamina/farmacologia , Inibidores da Captação de Dopamina/farmacologia , Fármacos atuantes sobre Aminoácidos Excitatórios/farmacologia , FMRFamida/farmacologia , Fluorenos/farmacologia , Neuropeptídeo Y/farmacologia , Peptídeo YY/farmacologia , Piperazinas/farmacologia , Serotoninérgicos/farmacologia , Compostos de Espiro/farmacologia , Sulpirida/farmacologia
13.
Insect Biochem Mol Biol ; 113: 103224, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31446031

RESUMO

In addition to its primary function as an insect repellent, DEET has many "off-label" properties, including a deterrent effect on the attraction of gravid female mosquitoes. DEET negatively affects oviposition sites. While deorphanizing odorant receptors (ORs) using the Xenopus oocyte recording system, we have previously observed that DEET generated outward (inhibitory) currents on ORs sensitive to oviposition attractants. Here, we systematically investigated these inhibitory currents. We recorded dose-dependent outward currents elicited by DEET and other repellents on ORs from Culex quinquefasciatus, Aedes aegypti, and Anopheles gambiae. Similar responses were observed with other plant-derived and plant-inspired compounds, including methyl jasmonate and methyl dihydrojasmolate. Inward (regular) currents elicited by skatole upon activation of CquiOR21 were modulated when this oviposition attractant was coapplied with a repellent. Compounds that generate outward currents in ORs sensitive to oviposition attractants elicited inward currents in a DEET-sensitive receptor, CquiOR136. The best ligand for this receptor, methyl dihydrojasmolate, showed repellency activity but was not as strong as DEET in our test protocol.


Assuntos
Aedes/efeitos dos fármacos , Anopheles/efeitos dos fármacos , Culex/efeitos dos fármacos , Proteínas de Insetos/antagonistas & inibidores , Repelentes de Insetos/farmacologia , Oviposição/efeitos dos fármacos , Receptores Odorantes/antagonistas & inibidores , Aedes/fisiologia , Animais , Anopheles/fisiologia , Quimiotaxia/efeitos dos fármacos , Culex/fisiologia , DEET/farmacologia , Mentol/análogos & derivados , Mentol/farmacologia , Piperidinas/farmacologia , Propionatos/farmacologia
14.
Res Vet Sci ; 125: 279-284, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31326704

RESUMO

Mutation of the PhoP/Q two-component system decreases the expression of ybjX and pagP encoding outer membrane proteins, and mutation of ybjX or pagP attenuates avian pathogenic Escherichia coli (APEC) pathogenicity. However, whether ybjX/pagP mutation (double-deletion mutant) has a synergistic effect on pathogenicity remains unknown. Herein, electrophoresis mobility shift assay (EMSA) experiments showed that the PhoP/Q system regulated ybjX and pagP transcription indirectly. The APECΔybjX/pagP mutant strain, constructed using the Red recombination method, exhibited reduced invasion of chicken embryo fibroblast (DF-1) cells, but had no effect on virulence in a chicken model. Using RNA sequencing to identify differential mRNAs in APECΔybjXΔpagP and native strains, we revealed up-regulation of genes involved in the bacterial chemotaxis pathway. The ybjX/pagP mutant strain displayed significantly increased motility, suggesting that double deletion of ybjX and pagP enhances motility via the bacterial chemotaxis pathway.


Assuntos
Aciltransferases/metabolismo , Infecções por Escherichia coli/veterinária , Proteínas de Escherichia coli/metabolismo , Escherichia coli/metabolismo , Aciltransferases/genética , Animais , Quimiotaxia , Embrião de Galinha , Galinhas , Escherichia coli/genética , Infecções por Escherichia coli/microbiologia , Proteínas de Escherichia coli/genética , Proteínas de Membrana/genética , Movimento , Mutação , Doenças das Aves Domésticas/microbiologia , Virulência , Fatores de Virulência/genética
15.
Nat Commun ; 10(1): 3202, 2019 07 19.
Artigo em Inglês | MEDLINE | ID: mdl-31324786

RESUMO

C. elegans worms exhibit a natural chemotaxis towards food cues. This provides a potential platform to study the interactions between stimulus valence and innate behavioral preferences. Here we perform a comprehensive set of choice assays to measure worms' relative preference towards various attractants. Surprisingly, we find that when facing a combination of choices, worms' preferences do not always follow value-based hierarchy. In fact, the innate chemotaxis behavior in worms robustly violates key rationality paradigms of transitivity, independence of irrelevant alternatives and regularity. These violations arise due to asymmetric modulatory effects between the presented options. Functional analysis of the entire chemosensory system at a single-neuron resolution, coupled with analyses of mutants, defective in individual neurons, reveals that these asymmetric effects originate in specific sensory neurons.


Assuntos
Comportamento Animal/fisiologia , Caenorhabditis elegans/fisiologia , Quimiotaxia/fisiologia , Células Receptoras Sensoriais/fisiologia , Animais , Sinais (Psicologia) , Tomada de Decisões/fisiologia , Modelos Biológicos
16.
Bull Exp Biol Med ; 167(3): 375-379, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31346881

RESUMO

In the process of optimization of heterologous expression of thermostable chemotaxis proteins CheW and CheY as industrially useful polypeptides, their direct influence on the cell growth kinetics and morphology of Escherichia coli was observed. CheW and CheY of bacteria of the genus Thermotoga, being expressed in recombinant form in E. coli cells, are involved in the corresponding signal pathways of the mesophilic microorganisms. The effects of such involvement in the metabolism of "host" cells are extremely diverse: from rapid aging of the culture to elongation of the stationary growth phase. We also discuss the mechanisms of the influence of the heterologous chemotaxis proteins on cells, their positive and negative effects, as well as potential applications in industry and biomedicine.


Assuntos
Bactérias/genética , Proteínas de Bactérias/biossíntese , Escherichia coli/metabolismo , Proteínas Quimiotáticas Aceptoras de Metil/biossíntese , Proteínas de Bactérias/genética , Reatores Biológicos/microbiologia , Quimiotaxia/genética , Escherichia coli/genética , Expressão Gênica/genética , Proteínas Quimiotáticas Aceptoras de Metil/genética
17.
Phys Rev E ; 99(6-1): 062414, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31330715

RESUMO

Collagen fibers, an important component of the extracellular matrix (ECM), can both inhibit and promote cellular migration. In vitro studies have revealed that the fibers' orientations are crucial to cellular invasion, while in vivo investigations have led to the development of tumor-associated collagen signatures (TACS) as an important prognostic factor. Studying biophysical regulation of cell invasion and the effect of the fibers' orientation not only deepens our understanding of the phenomenon, but also helps classify the TACSs precisely, which is currently lacking. We present a stochastic model for random or chemotactic migration of cells in fibrous ECM, and study the role of the various factors in it. The model provides a framework for quantitative classification of the TACSs, and reproduces quantitatively recent experimental data for cell motility. It also indicates that the spatial distribution of the fibers' orientations and extended correlations between them, hitherto ignored, as well as dynamics of cellular motion all contribute to regulation of the cells' invasion length, which represents a measure of metastatic risk. Although the fibers' orientations trivially affect randomly moving cells, their effect on chemotactic cells is completely nontrivial and unexplored, which we study in this paper.


Assuntos
Quimiotaxia , Colágeno/metabolismo , Modelos Biológicos , Neoplasias/patologia , Matriz Extracelular/metabolismo
18.
Biosci Biotechnol Biochem ; 83(11): 2163-2171, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31272289

RESUMO

Motile bacteria often exhibit chemotaxis toward favorable compounds. However, the diversity of bacteria that are attracted to a given substance is largely unknown. This study aimed to reveal the diversity of bacteria with natural chemotaxis towards methanol. We tried to enrich environmental chemotactic bacteria using a glass capillary that is half-filled with methanol solidified with agarose as a trap ("chemotaxis fishing"). The pilot experiment using methanol-chemotactic Methylobacterium aquaticum strain 22A enriched the cells by 46-fold. The method was then applied to bacterial suspensions from paddy water and plants. Depending on the isolation sources and the methods of motility induction, methylotrophic bacteria were enriched 1.2-330-fold. The fished isolates belong to 32 species in 18 genera, mainly containing Acinetobacter, Methylobacterium and Pseudomonas species. Our chemotaxis fishing unveiled a part of diversity of the bacteria with natural chemotaxis towards methanol.


Assuntos
Bactérias/citologia , Bactérias/efeitos dos fármacos , Quimiotaxia/efeitos dos fármacos , Metanol/farmacologia , Técnicas Microbiológicas/métodos , Plantas/microbiologia
19.
Int J Radiat Biol ; 95(11): 1498-1506, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31287373

RESUMO

Purpose: The aim of this study was to investigate whether low-dose ionizing radiation attenuates mast cell migration by modulating migration-associated signaling pathways and the expression of chemotactic cytokines.Materials and methods: IgE-sensitized RBL-2H3 mast cells were exposed with ionizing radiation at 0.01, 0.05, 0.1, or 0.5 Gy using a 137Cs γ-irradiator and stimulated with 2,4-dinitrophenol-human serum albumin. Cell migration was determined using a transwell assay system, F-actin distribution using Alex Fluor 488-conjugated phalloidin, expression of various signaling proteins by Western blotting, mRNA expression by RT-PCR.Results: Low-dose ionizing radiation significantly suppressed mast cell migration induced by IgE-mediated mast cell activation. Furthermore, low-dose ionizing radiation altered cell morphology, as reflected by changes in F-actin distribution, and inhibited the activation of PI3K, Btk, Rac1, and Cdc42. These effects were mediated by Nr4a2, an immune-modulating factor. Knockdown of Nr4a2 reduced mast cell migration, inhibited the PI3K and Btk signaling pathways, and reduced expression of the chemotactic cytokine monocyte chemoattractant protein-1 (MCP-1). We further demonstrated that direct blockade of MCP-1 using neutralizing antibodies inhibits mast cell migration.Conclusion: Low-dose ionizing radiation inhibits mast cell migration through the regulation production of MCP-1 by Nr4a2 in the activated mast cell system.


Assuntos
Movimento Celular/efeitos da radiação , Quimiocina CCL2/metabolismo , Mastócitos/efeitos da radiação , Membro 2 do Grupo A da Subfamília 4 de Receptores Nucleares/metabolismo , Interferência de RNA , Actinas/metabolismo , Animais , Linhagem Celular Tumoral , Radioisótopos de Césio , Quimiotaxia , Citocinas/metabolismo , Raios gama , Perfilação da Expressão Gênica , Regulação da Expressão Gênica , Mastócitos/citologia , Faloidina/metabolismo , Ratos , Transdução de Sinais
20.
Infect Immun ; 87(9)2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31262979

RESUMO

Helicobacter pylori is a pathogen that chronically colonizes the stomachs of approximately half of the world's population and contributes to the development of gastric inflammation. We demonstrated previously in vivo that H. pylori uses motility to preferentially colonize injury sites in the mouse stomach. However, the chemoreceptor responsible for sensing gastric injury has not yet been identified. In this study, we utilized murine gastric organoids (gastroids) and mutant H. pylori strains to investigate the components necessary for H. pylori chemotaxis. High-intensity 730-nm light (two-photon photodamage) was used to cause single-cell damage in gastroids, and repair of the damage was monitored over time; complete repair occurred within ∼10 min in uninfected gastroids. Wild-type H. pylori accumulated at the damage site after gastric damage induction. In contrast, mutants lacking motility (ΔmotB) or chemotaxis (ΔcheY) did not accumulate at the injury site. Using mutants lacking individual chemoreceptors, we found that only TlpB was required for H. pylori accumulation, while TlpA, TlpC, and TlpD were dispensable. All strains that were able to accumulate at the damage site limited repair. When urea (an identified chemoattractant sensed by TlpB) was microinjected into the gastroid lumen, it prevented the accumulation of H. pylori at damage sites. Overall, our findings demonstrate that H. pylori colonizes and limits repair at damage sites via chemotactic motility that requires the TlpB chemoreceptor to sense signals generated by gastric epithelial cells.


Assuntos
Proteínas de Bactérias/fisiologia , Fatores Quimiotáticos/farmacologia , Quimiotaxia/fisiologia , Infecções por Helicobacter/microbiologia , Helicobacter pylori/efeitos dos fármacos , Gastropatias/microbiologia , Animais , Modelos Animais de Doenças , Mucosa Gástrica/microbiologia , Camundongos
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