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1.
Genomics ; 116(1): 110777, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38163572

RESUMO

Genomic studies with Salmonella enterica serovar Typhimurium reveal a crucial role of horizontal gene transfer (HGT) in the acquisition of accessory cellular functions involved in host-interaction. Many virulence genes are located in genomic islands, plasmids and prophages. GreA and GreB proteins, Gre factors, interact transiently with the RNA polymerase alleviating backtracked complexes during transcription elongation. The overall effect of Gre factors depletion in Salmonella expression profile was studied. Both proteins are functionally redundant since only when both Gre factors were depleted a major effect in gene expression was detected. Remarkably, the accessory gene pool is particularly sensitive to the lack of Gre factors, with 18.6% of accessory genes stimulated by the Gre factors versus 4.4% of core genome genes. Gre factors involvement is particularly relevant for the expression of genes located in genomic islands. Our data reveal that Gre factors are required for the expression of accessory genes.


Assuntos
Proteínas de Bactérias , Salmonella typhimurium , Salmonella typhimurium/genética , Salmonella typhimurium/metabolismo , Plasmídeos , Virulência/genética , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo
2.
Sensors (Basel) ; 23(15)2023 Jul 25.
Artigo em Inglês | MEDLINE | ID: mdl-37571449

RESUMO

Experiences of virtual reality (VR) can easily break if the method of evaluating subjective user states is intrusive. Behavioral measures are increasingly used to avoid this problem. One such measure is eye tracking, which recently became more standard in VR and is often used for content-dependent analyses. This research is an endeavor to utilize content-independent eye metrics, such as pupil size and blinks, for identifying mental load in VR users. We generated mental load independently from visuals through auditory stimuli. We also defined and measured a new eye metric, focus offset, which seeks to measure the phenomenon of "staring into the distance" without focusing on a specific surface. In the experiment, VR-experienced participants listened to two native and two foreign language stimuli inside a virtual phone booth. The results show that with increasing mental load, relative pupil size on average increased 0.512 SDs (0.118 mm), with 57% reduced variance. To a lesser extent, mental load led to fewer fixations, less voluntary gazing at distracting content, and a larger focus offset as if looking through surfaces (about 0.343 SDs, 5.10 cm). These results are in agreement with previous studies. Overall, we encourage further research on content-independent eye metrics, and we hope that hardware and algorithms will be developed in the future to further increase tracking stability.


Assuntos
Realidade Virtual , Humanos , Percepção Auditiva , Idioma , Interface Usuário-Computador , Inquéritos e Questionários
3.
Rep Pract Oncol Radiother ; 28(6): 720-727, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-38515815

RESUMO

Background: Several measurements defining the expected 30-day mortality (30-DM) to use in audit of radiation oncology departments have been proposed. However, its external validity is limited because of the lack of data from non-English speaking countries. This study assessed 30-DM in patients treated with palliative radiotherapy (PRT) in a Chilean-reference radiotherapy centre and explored if there had been tailored treatment at the end of life. Materials and methods: Retrospective data collection was carried out for all patients treated at our institution between 1st January 2018 and 31st December 2021. Individual factors were modelled first to check for univariate association with 30-DM, those variables with a significance level of < 0.05 were considered for the final multivariable model. Results: 3,357 patients were included. The most common primary malignancies were breast (22%) and lung (16.1%). The most common treatment sites were bone (47.7%) and brain (12.2%). Overall, 30-DM was 14.7%, this rate was higher in patients treated for brain metastases (25.7%) and thoracic palliation (22.1%). 30-DM was associated with poor performance status (p < 0.01), lung and esophageal-gastric cancer (p = 0.04 and p = 0.02, respectively), metastases other than bone (p < 0.01), brain metastases (p < 0.01) and private health insurance (p <0.01). Conclusions: In patients treated for brain metastasis and thoracic palliation 30-DM was higher than suggested benchmarks. Moreover, in these groups long courses of PRT were often performed. Audit data should be useful for planning interventions that improve selection of patients and prompting review of policies for indication and fractionation schedules of PRT.

4.
Breast Cancer Res Treat ; 191(1): 219-220, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34609641

RESUMO

We retrospectively reviewed the data from patients ≥ 70 years old treated between January 2012 and January 2017. Axillary staging was scarcely used in the therapeutic algorithm but arm lymphedema was significantly associated to axillar dissection (p=0.04) and regional nodal irradiation (p = 0.02). Aggressive management of axilla did not provide relevant information for deciding chemotherapy but added morbidity.


Assuntos
Neoplasias da Mama , Idoso , Axila/patologia , Neoplasias da Mama/patologia , Dissecação , Feminino , Humanos , Excisão de Linfonodo , Linfonodos/patologia , Estadiamento de Neoplasias , Estudos Retrospectivos , Biópsia de Linfonodo Sentinela
5.
Molecules ; 26(9)2021 Apr 26.
Artigo em Inglês | MEDLINE | ID: mdl-33925792

RESUMO

Low-density polyethylene (LDPE) sheets (3.0 ± 0.1 cm) received sequential treatment, first by the action of direct-current low-pressure plasma (DC-LPP) with a 100% oxygen partial pressure, 3.0 × 10-2 mbar pressure, 600 V DC tension, 5.6 cm distance, 6-min treatment. Then, sheets were submitted to TiO2 photocatalysis at UV radiation at 254 nm (TiO2/UV) with a pH value of 4.5 ± 0.2 and a TiO2 concentration of 1 gL-1. We achieved a complementary effect on the transformation of LDPE films. With the first treatment, ablation was generated, which increased hydrophilicity. With the second treatment, the cavities appeared. The changes in the LDPE sheets' hydrophobicity were measured using the static contact angle (SCA) technique. The photocatalytic degradation curve at 400 h revealed that the DC-LPP photocatalysis sequential process decreased SCA by 82°. This was achieved by the incorporation of polar groups, which increased hydrophilicity, roughness, and rigidity by 12 and 38%, respectively. These sequential processes could be employed for LDPE and other material biodegradation pretreatment.

6.
Rep Pract Oncol Radiother ; 25(1): 64-67, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31889924

RESUMO

INTRODUCTION: Single fraction radiotherapy (SFR) is effective in palliation of symptoms related to advanced cancer. Despite this, several studies have shown that the trend towards multiple fraction treatment (MFR) is largely maintained. Even in patients with limited life expectancy, SFR is significantly underutilized in current practice. CASES DESCRIPTION: Four patients diagnosed with advanced cancer who developed soft tissue lesions were treated with SFR due to frailty and/or a poor performance status. CONCLUSION: Despite the effectiveness of SFR is well-established in BM, its use in symptoms caused by soft tissue lesions have been underreported. SFR could be a good option for providing palliation in some patients, particularly in those who are frail or have a poor performance status.

7.
Combust Flame ; 189: 46-61, 2018 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31341327

RESUMO

This experimental study explored the response of burning liquid fuel droplets to one-dimensional acoustic standing waves created within a closed, atmospheric waveguide. Building upon prior droplet combustion studies quantifying mean and temporal flame response of several alternative fuels to moderate acoustic excitation (Sevilla-Esparza, et al., Combustion and Flame, 161(6):1604-1619, 2014), the present work focused on higher amplitude acoustic forcing observed to create periodic partial extinction and reignition (PPER) of flames enveloping the droplet. Detailed examination of ethanol droplets exposed to a range of acoustic forcing conditions (frequencies and amplitudes in the vicinity of a pressure node) yielded several different combustion regimes: one with sustained oscillatory flames, one with PPER, and then full extinction at very high excitation amplitudes. Phase-locked OH* chemiluminescence imaging and local temporal pressure measurements allowed quantification of the combustion-acoustic coupling through the local Rayleigh index. Similar behavior was observed for JP-8 and liquid synthetic fuel derived via the Fischer-Tropsch process, but with quantitative differences based on different reaction time scales. Estimates of the mean and oscillatory strain rates experienced by the flames during excitation assisted with interpreting specific relationships among acoustic, chemical, and fluid mechanical/straining time scales that can lead to a greater understanding of PPER.

8.
Int J Sport Nutr Exerc Metab ; 28(6): 580-585, 2018 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-29405780

RESUMO

Aspiring female physique athletes are often encouraged to ingest relatively high levels of dietary protein in conjunction with their resistance training programs. However, there is little to no research investigating higher versus lower protein intakes in this population. This study examined the influence of a high versus low-protein diet in conjunction with an 8-week resistance training program in this population. A total of 17 females (21.2 ± 2.1 years; 165.1 ± 5.1 cm; 61 ± 6.1 kg) were randomly assigned to a high-protein diet (HP: 2.5 g·kg-1·day-1; n = 8) or a low-protein diet (LP: 0.9 g·kg-1·day-1, n = 9) and were assessed for body composition and maximal strength prior to and after the 8-week protein intake and exercise intervention. Fat-free mass increased significantly more in the HP group as compared with the LP group (p = .009), going from 47.1 ± 4.5 to 49.2 ± 5.4 kg (+2.1 kg) and from 48.1 ± 2.7 to 48.7 ± 2 kg (+0.6 kg) in the HP and LP groups, respectively. Fat mass significantly decreased over time in the HP group (14.1 ± 3.6 to 13.0 ± 3.3 kg; p < .01), but no change was observed in the LP group (13.2 ± 3.7 to 12.5 ± 3.0 kg). Although maximal strength significantly increased in both groups, there were no differences in strength improvements between the two groups. In aspiring female physique athletes, a higher protein diet is superior to a lower protein diet in terms of increasing fat-free mass in conjunction with a resistance training program.


Assuntos
Composição Corporal , Proteínas Alimentares/administração & dosagem , Treinamento Resistido , Fenômenos Fisiológicos da Nutrição Esportiva , Atletas , Metabolismo Basal , Feminino , Treinamento Intervalado de Alta Intensidade , Humanos , Força Muscular , Adulto Jovem
9.
J Strength Cond Res ; 32(5): 1207-1213, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29324578

RESUMO

Colquhoun, RJ, Gai, CM, Aguilar, D, Bove, D, Dolan, J, Vargas, A, Couvillion, K, Jenkins, NDM, and Campbell, BI. Training volume, not frequency, indicative of maximal strength adaptations to resistance training. J Strength Cond Res 32(5): 1207-1213, 2018-To compare the effects of a high versus a moderate training frequency on maximal strength and body composition. Twenty-eight young, healthy resistance-trained men were randomly assigned to either: 3× per week (3×; n = 16) or 6× per week (6×; n = 12). Dependent variables (DVs) assessed at baseline and after the 6-week training intervention included: squat 1 repetition maximum (SQ1RM), bench press 1RM (BP1RM), deadlift 1RM (DL1RM), powerlifting total (PLT), Wilk's coefficient (WC), fat-free mass (FFM), and fat mass. Data for each DV were analyzed using a 2 × 2 between-within factorial repeated-measures analysis of variance. There was a main effect for time (p < 0.001) for SQ1RM (3×: +16.8 kg; 6×: +16.7 kg), BP1RM (3×: +7.8 kg; 6×: +8.8 kg), DL1RM (3×: +19 kg; 6×: +21 kg), PLT (3×: +43.6 kg; 6×: +46.5 kg), WC (3×: +27; 6×: +27.1), and FFM (3×: +1.7 kg; 6×: +2.6 kg). There were no group × time interactions or main effects for group. The primary finding was that 6 weeks of resistance training led to significant increases in maximal strength and FFM. In addition, it seems that increased training frequency does not lead to additional strength improvements when volume and intensity are equated. High-frequency (6× per week) resistance training does not seem to offer additional strength and hypertrophy benefits over lower frequency (3× per week) when volume and intensity are equated. Coaches and practitioners can therefore expect similar increases in strength and lean body mass with both 3 and 6 weekly sessions.


Assuntos
Força Muscular/fisiologia , Músculo Esquelético/fisiologia , Treinamento Resistido/métodos , Adaptação Fisiológica , Adolescente , Adulto , Composição Corporal/fisiologia , Humanos , Masculino , Adulto Jovem
10.
Rev Med Chil ; 146(1): 32-38, 2018 Jan.
Artigo em Espanhol | MEDLINE | ID: mdl-29806675

RESUMO

BACKGROUND: Kaposi's sarcoma (KS) is a rare tumor that affects mainly immunodeficient and elderly patients. AIM: To describe the features and outcomes of a cohort of patients with different types of KS treated locally with radiotherapy (RT). PATIENTS AND METHODS: Retrospective review of patients with KS referred to our radiation oncology center for local treatment of symptomatic lesions that did not respond to high activity anti-retroviral therapy or chemotherapy. RESULTS: Between January 1995 and December 2016, 20 patients with a median age of 40 years (18 males) with KS were assessed and treated with RT due to symptomatic lesions. The most common KS type was epidemic in 15 patients, followed by the classic type in three and the iatrogenic variety in two. In patients with non-epidemic varieties, SK was exclusively cutaneous, while visceral involvement was present in 46% of patients with epidemic SK. Complete response was observed in 95% of cases. Skin toxicity caused by RT was mild in all cases. CONCLUSIONS: RT may be considered as a reasonable local treatment choice in classic, iatrogenic and epidemic varieties of KS.


Assuntos
Fracionamento da Dose de Radiação , Sarcoma de Kaposi/radioterapia , Neoplasias Cutâneas/radioterapia , Adulto , Estudos de Coortes , Feminino , Humanos , Masculino , Indução de Remissão , Estudos Retrospectivos , Resultado do Tratamento
11.
PLoS Comput Biol ; 12(2): e1004706, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26859137

RESUMO

Significant cell-to-cell heterogeneity is ubiquitously observed in isogenic cell populations. Consequently, parameters of models of intracellular processes, usually fitted to population-averaged data, should rather be fitted to individual cells to obtain a population of models of similar but non-identical individuals. Here, we propose a quantitative modeling framework that attributes specific parameter values to single cells for a standard model of gene expression. We combine high quality single-cell measurements of the response of yeast cells to repeated hyperosmotic shocks and state-of-the-art statistical inference approaches for mixed-effects models to infer multidimensional parameter distributions describing the population, and then derive specific parameters for individual cells. The analysis of single-cell parameters shows that single-cell identity (e.g. gene expression dynamics, cell size, growth rate, mother-daughter relationships) is, at least partially, captured by the parameter values of gene expression models (e.g. rates of transcription, translation and degradation). Our approach shows how to use the rich information contained into longitudinal single-cell data to infer parameters that can faithfully represent single-cell identity.


Assuntos
Expressão Gênica/fisiologia , Modelos Biológicos , Saccharomyces cerevisiae/citologia , Saccharomyces cerevisiae/fisiologia , Análise de Célula Única , Biologia Computacional , Expressão Gênica/genética , Técnicas Analíticas Microfluídicas , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo
13.
J Natl Compr Canc Netw ; 12(3): 365-73, 2014 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-24616542

RESUMO

The purpose of this prospective cohort study was to assess the feasibility of outpatient treatment in patients with cancer and objectively confirmed pulmonary embolism (PE), and to compare the performance of the different prognostic scales available in this setting. Patients were selected for outpatient management according to a set of exclusion criteria. Outcomes at 30 and 90 days of follow-up included thromboembolic recurrences, major bleeding, and all-cause death. The performance of 4 prognostic scales (Pulmonary Embolism Severity Index, Geneva Prognostic Score, POMPE-C, and Registro Informatizado de Enfermedad Tromboembólica [RIETE registry]) was evaluated. Of 138 patients, 62 (45%) were managed as outpatients. Incidental PE constituted 47% of the sample. Most patients treated at home had an incidentally detected PE (89%). The rate of recurrence and major bleeding events was similar in both groups. Mortality rates were higher for patients admitted to the hospital compared with outpatients at 30 days (18% vs 3%; P=.06) and 90 days (34% vs 10%; P=.001) of follow-up. None of the patients selected for home treatment required further admission because of PE complications. None of the prognostic models developed for symptomatic PE was significantly associated with 30-day mortality. Improved survival outcomes were observed in incidentally detected PEs compared with acute symptomatic events (overall mortality rates, 3.2% vs 18.4%; P=.006). A large proportion of patients with cancer and PE may be safely treated as outpatients, especially those with incidental PE. Cancer-specific prognostic scales including incidental PE should be developed for the optimal management of PE in this setting.


Assuntos
Neoplasias/complicações , Pacientes Ambulatoriais , Embolia Pulmonar/tratamento farmacológico , Embolia Pulmonar/etiologia , Idoso , Anticoagulantes/administração & dosagem , Anticoagulantes/uso terapêutico , Humanos , Masculino , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Neoplasias/diagnóstico , Neoplasias/terapia , Prognóstico , Estudos Prospectivos , Embolia Pulmonar/diagnóstico , Embolia Pulmonar/mortalidade , Fatores de Risco , Resultado do Tratamento
14.
J Nanosci Nanotechnol ; 14(7): 4918-29, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24757963

RESUMO

Carbon nanotubes (CNTs) and sepiolite (SEP) were modified in order to improve their compatibility with the polypropylene (PP) matrix. Carboxylic groups were introduced into the CNTs through an oxidative treatment and aliphatic chains were incorporated on SEP by ion exchange of a cationic surfactant. Maleic anhydride grafted polypropylene (PPgMA) was mixed with neat PP to introduce polar groups into the polymer matrix. Composites including modified and non-modified fillers were prepared by melt extrusion. Dispersion and interaction of the CNTs with the PP and PPgMA matrices were evaluated by Raman spectroscopy while a focused ion beam/scanning electron microscopy (FIB/SEM) was used for SEP containing composites. Scratch resistance, microhardness, dynamic friction and wear were determined. Raman spectroscopy shows that the introduction of polar groups into PP matrices has a positive effect on the dispersion of modified CNTs. FIB/SEM results show that the modification of SEP improves its dispersion in the polypropylene matrix; filler clusters found in the PPgMA matrix are much times smaller than those in the neat PP. Despite of SEP agglomerates in the composites, a good interaction between both phases is seen; SEP particles are fully coated and embedded inside the PP matrix. The 'lack of cooperation' between unmodified PP and its fillers results in nanocomposites with larger residual depths; by contrast, PPgMA does 'cooperate' with its fillers so that the nanocomposites in scratch resistance testing have smaller residual depths R(h) than the neat PPgMA. Addition of the fillers to PPgMA also increases the hardness. As for wear rates, some our fillers provide higher and some lower wear rates than PP.

15.
Anthropol Anz ; 80(1): 23-29, 2023 Jan 18.
Artigo em Inglês | MEDLINE | ID: mdl-36155612

RESUMO

The existence of a third root in the mandibular first molars may have implications for certain dental treatments; however, its greatest relevance could be in anthropological and forensic sciences, because its prevalence varies significantly according to ethnic groups. The purpose of this research was to determine the prevalence of radix entomolaris (RE) in a sample of Chilean people. A random sample of 1330 digital periapical radiographs of endodontically treated mandibular first molars (551 males and 779 females, aged between 18 and 87 years) were evaluated. The prevalence of RE, its distribution by sex and root canal lengths were determined. Evidence demonstrated that the formation of RE is associated with ancestry and its frequency is variable according to populations studied, being more frequent in Asians and Native Americans. The prevalence of RE in the studied people was 3.16%, similar to frequencies reported in European individuals (3.4%-4.2%). The 61.90% of RE were located at the right side of the mandible and 38.10% at the left side. The average working length of RE was 19.52 mm. No statistically significant differences in frequencies were observed by sex (p = 0.19). The prevalence of RE varies among continental population groups. However, due to human migration, the frequency of this physical trait could be modified in specific geographic regions. The observed prevalence of RE in the study group was similar to the prevalence ranges observed for European ancestry populations and it was considerably lower than the data reported for non-Europeans. The absence of sexual dimorphism is consistent with results of previous studies performed worldwide.


Assuntos
Dentição , Raiz Dentária , Masculino , Feminino , Humanos , Adolescente , Adulto Jovem , Adulto , Pessoa de Meia-Idade , Idoso , Idoso de 80 Anos ou mais , Chile/epidemiologia , Raiz Dentária/diagnóstico por imagem , Dente Molar , Etnicidade , Mandíbula
16.
Clin Transl Oncol ; 24(9): 1800-1808, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-35474170

RESUMO

BACKGROUND: Breast cancer (BC) prevalence steadily increases in older patients but their treatment is based on the geriatric evaluations of comorbidities and potential benefits proved in clinical trials with younger patients. The lack of better decision-making tools urges to promote the search for new prognostic markers. The association between inflammation, aging and cancer may be crucial for better treatment selection. We sought to analyze its impact on the survival of older BC patients, evaluating the interaction with age and comorbidities. METHODS: We evaluated the relationship between inflammatory biomarkers at BC diagnosis (circulating blood cell counts and inflammatory indexes) and BC-related and not related mortality rate, evaluating the influence of comorbidities and age through the competitive risks assessment. RESULTS: We analyzed 148 consecutive BC patients aged ≥ 70 years old, diagnosed with BC and regional lymph node metastases. After the median follow-up of 51.5 months, 59 patients died (28 due to breast cancer progression and 31 because of other causes). Increased levels of circulating monocytes, neutrophils and neutrophil-to-lymphocytes ratio and decreased level of eosinophils and eosinophil multiple by neutrophils-to-lymphocytes ratio were associated with higher probability of BC-related death but not with death related to other causes. CONCLUSION: Our data suggest a role of inflammatory parameters as a possible prognostic tool in therapeutic decision-making process in older patients with BC, as increased level of inflammation was associated with cancer-specific mortality. Prospective studies may give the possibility of refining the geriatric evaluation for BC treatment in elderly.


Assuntos
Neoplasias da Mama , Idoso , Mama/patologia , Neoplasias da Mama/patologia , Feminino , Humanos , Inflamação/patologia , Prognóstico , Estudos Prospectivos
17.
Surg Neurol Int ; 13: 45, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35242411

RESUMO

BACKGROUND: Cerebellar liponeurocytoma is rare intracranial tumor appearing mostly in the posterior fossa. CASE DESCRIPTION: We hereby report a long follow-up of a case of cerebellar liponeurocytoma in a 60-year-old female. At first, she presented in March of 2010 with the symptoms of hydrocephalus and was found to have a lesion located in the fourth ventricle. The tumor was resected with a small remnant around the brainstem which grew on serial imaging. Due to slow tumor growth, the patient was treated with conformal radiotherapy and was kept under follow-up with both outpatient visits and serial brain imaging. In 2018, due to low back pain and lumbar radicular pain, a new set of images of the spine was obtained which revealed multilevel intradural tumor spinal dissemination. The patient further underwent an open spinal biopsy at the level of L5 which revealed the same pathology of the intracranial tumor. The patient went on to receive total spine irradiation. CONCLUSION: This case report describes a rare metastatic phenomenon to the spinal cord of the exact same pathology and grade of an intracranial cerebellar liponeurocytoma tumor.

18.
PLoS One ; 17(8): e0271172, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35930546

RESUMO

It is an increasingly accepted idea that biological diversity stabilizes ecosystem processes and the services they provide to society. By reducing biomass fluctuation, biodiversity could mitigate the impact of changing environmental conditions on rural incomes as long as people exploits a diverse set of natural assets. This effect is analogous to the risk-spreading function of financial portfolios. This paper presents evidence of the portfolio effect for an open-access artisanal fishery in an estuarine ecosystem, located in a Colombian Biosphere Reserve. Using catch statistics from 2002 to 2018, we evaluate the contribution of catch diversity to the stabilization of fishing income. We find that changes in catch composition are related to seasonal and interannual variations in salinity conditions. The portfolio effect arises from asynchronous fluctuations of fish species due to fluctuating environmental conditions. Catch diversification, instead of specialization, help achieve resilient fisheries.


Assuntos
Ecossistema , Pesqueiros , Animais , Biodiversidade , Conservação dos Recursos Naturais , Peixes , Humanos , Caça , Renda
19.
Microorganisms ; 10(10)2022 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-36296197

RESUMO

Rdar biofilm formation of Salmonella typhimurium and Escherichia coli is a common ancient multicellular behavior relevant in cell-cell and inter-organism interactions equally, as in interaction with biotic and abiotic surfaces. With the expression of the characteristic extracellular matrix components amyloid curli fimbriae and the exopolysaccharide cellulose, the central hub for the delicate regulation of rdar morphotype expression is the orphan transcriptional regulator CsgD. Gre factors are ubiquitously interacting with RNA polymerase to selectively overcome transcriptional pausing. In this work, we found that GreA/GreB are required for expression of the csgD operon and consequently the rdar morphotype. The ability of the Gre factors to suppress transcriptional pausing and the 147 bp 5'-UTR of csgD are required for the stimulatory effect of the Gre factors on csgD expression. These novel mechanism(s) of regulation for the csgD operon might be relevant under specific stress conditions.

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