Lipoteichoic acid depletion in Lactobacillus impacts cell morphology and stress response but does not abolish mercury surface binding

Lipoteichoic acid (LTA) is a key component of the cell wall of most Gram-positive bacteria and plays many structural and functional roles. In probiotic lactobacilli, the function of LTA in mediating bacteria/host cross-talk has been evidenced and it has been postulated that, owing to its anionic nature, LTA may play a role in toxic metal sequestration by these bacteria. However, studies on this last aspect employing strains unable to synthesise LTA are lacking. We have inactivated the LTA polymerase encoding gene ltaS in two different Lactobacillus plantarum strains. Analysis of LTA contents in wild-type and ltaS mutant strains corroborated the role of this gene as a major contributor to LTA synthesis in L. plantarum. The mutant strains displayed strain-dependent anomalous cell morphologies that resulted in elongated or irregular cells with aberrant septum formation. They also exhibited higher sensitivity to several stresses (osmotic and heat) and to antimicrobials that target the cell wall. The toxicity of inorganic [(Hg(II)] and organic mercury (methyl-Hg) was also increased upon ltaS mutation in a strain-dependent manner. However, the mutant strains showed 0 to 50% decrease in their capacity of Hg binding compared to their corresponding parental strains. This result suggests a partial contribution of LTA to Hg binding onto the cell surface that was dependent on the strain and the Hg form.

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Intestinal Mucus Alters the Ability of Probiotic Bacteria To Bind Aflatoxin B1 In Vitro

Applied and Environmental Microbiology ◽

10.1128/aem.70.10.6306-6308.2004 ◽

2004 ◽

Vol 70 (10) ◽

pp. 6306-6308 ◽

Cited By ~ 50

Author(s):

S. Gratz ◽

H. Mykkänen ◽

A. C. Ouwehand ◽

R. Juvonen ◽

S. Salminen ◽

...

Keyword(s):

Aflatoxin B1 ◽

Probiotic Bacteria ◽

Dependent Manner ◽

Surface Binding ◽

Intestinal Mucus ◽

Aflatoxin B ◽

Strain Dependent

ABSTRACT Several probiotics are known to bind aflatoxin B1 (AFB1) to their surfaces and to adhere to intestinal mucus. In this study, preincubation of two probiotic preparations with either AFB1 or mucus reduced the subsequent surface binding of mucus and AFB1, respectively, in a strain-dependent manner.

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Antibiotic Susceptibility Profile of Bifidobacteria as Affected by Oxgall, Acid, and Hydrogen Peroxide Stress

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00261-06 ◽

2006 ◽

Vol 51 (1) ◽

pp. 169-174 ◽

Cited By ~ 28

Author(s):

E. Kheadr ◽

N. Dabour ◽

C. Le Lay ◽

C. Lacroix ◽

I. Fliss

Keyword(s):

Oxidative Stress ◽

Hydrogen Peroxide ◽

Cell Wall ◽

Gastrointestinal Tract ◽

Dependent Manner ◽

Intestinal Infections ◽

Antibiotic Associated Diarrhea ◽

Strain Dependent ◽

Microdilution Broth ◽

Peroxide Stress

ABSTRACT The effects of acid, oxgall, and H2O2 on susceptibilities to antibiotics and nisin were examined for 13 strains of bifidobacteria. Susceptibilities to ampicillin, cloxacillin, penicillin, vancomycin, kanamycin, neomycin, paramomycin, streptomycin, chloramphenicol, erythromycin, tetracycline, and nisin A were assayed by a microdilution broth method. Acid-, oxgall- and H2O2-stressed variants were produced and assayed. Exposure to a pH of 2.0 for 60 min reduced susceptibilities to cloxacillin and nisin A but increased susceptibilities to ampicillin, vancomycin, aminoglycosides, chloramphenicol, and erythromycin in a strain-dependent manner. Exposure to oxgall (0.3%) for 90 min increased susceptibilities to cell wall-directed antibiotics and aminoglycosides but increased resistances to tetracycline and nisin A. Oxidative stress increased the susceptibilities of 70% of the strains to ampicillin and chloramphenicol, of 50% of the strains to cloxacillin and tetracycline, and of 40% of the strains to erythromycin but did not affect susceptibilities to vancomycin, kanamycin, and nisin A. This study shows that exposure of bifidobacteria to stressful conditions resembling those in the gastrointestinal tract may substantially modify their susceptibilities to antibiotics and may thus affect their probiotic capacities, especially when they are used for the management of intestinal infections and antibiotic-associated diarrhea.

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Mouse paternal-RNAs initiate pattern of metabolic disorders in a strain dependent manner

Endocrine Abstracts ◽

10.1530/endoabs.41.ep400b ◽

2016 ◽

Author(s):

Guzide Satir Basaran ◽

Yagut Akbarova ◽

Kezban Korkmaz ◽

Kursad Unluhizarci ◽

Francois Cuzin ◽

...

Keyword(s):

Metabolic Disorders ◽

Dependent Manner ◽

Strain Dependent

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Antifungal Activity Directed Toward the Cell Wall by 2-Cyclohexylidenhydrazo- 4-Phenyl-Thiazole Against Candida albicans

Infectious Disorders - Drug Targets ◽

10.2174/1871526518666180531101605 ◽

2019 ◽

Vol 19 (4) ◽

pp. 428-438 ◽

Cited By ~ 1

Author(s):

Nívea P. de Sá ◽

Ana P. Pôssa ◽

Pilar Perez ◽

Jaqueline M.S. Ferreira ◽

Nayara C. Fonseca ◽

...

Keyword(s):

Cell Wall ◽

Candida Albicans ◽

Antifungal Activity ◽

Mammalian Cells ◽

C Elegans ◽

Buccal Epithelial Cells ◽

Mutant Strains ◽

Low Toxicity ◽

High Concentrations ◽

Mic Value

Background: The increasing incidence of invasive forms of candidiasis and resistance to antifungal therapy leads us to seek new and more effective antifungal compounds. Objective: To investigate the antifungal activity and toxicity as well as to evaluate the potential targets of 2- cyclohexylidenhydrazo-4-phenyl-thiazole (CPT) in Candida albicans. Methods: The antifungal activity of CPT against the survival of C. albicans was investigated in Caenorhabditis elegans. Additionally, we determined the effect of CPT on the inhibition of C. albicans adhesion capacity to buccal epithelial cells (BECs), the toxicity of CPT in mammalian cells, and the potential targets of CPT in C. albicans. Results: CPT exhibited a minimum inhibitory concentration (MIC) value of 0.4-1.9 µg/mL. Furthermore, CPT at high concentrations (>60 x MIC) showed no or low toxicity in HepG2 cells and <1% haemolysis in human erythrocytes. In addition, CPT decreased the adhesion capacity of yeasts to the BECs and prolonged the survival of C. elegans infected with C. albicans. Analysis of CPT-treated cells showed that their cell wall was thinner than that of untreated cells, especially the glucan layer. We found that there was a significantly lower quantity of 1,3-β-D-glucan present in CPT-treated cells than that in untreated cells. Assays performed on several mutant strains showed that the MIC value of CPT was high for its antifungal activity on yeasts with defective 1,3-β-glucan synthase. Conclusion: In conclusion, CPT appears to target the cell wall of C. albicans, exhibits low toxicity in mammalian cells, and prolongs the survival of C. elegans infected with C. albicans.

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Gram-positive bacteria cell wall-derived lipoteichoic acid induces inflammatory alveolar bone loss through prostaglandin E production in osteoblasts

Scientific Reports ◽

10.1038/s41598-021-92744-5 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Tsukasa Tominari ◽

Ayumi Sanada ◽

Ryota Ichimaru ◽

Chiho Matsumoto ◽

Michiko Hirata ◽

...

Keyword(s):

Cell Wall ◽

Bone Loss ◽

Alveolar Bone ◽

Osteoclast Differentiation ◽

Lipoteichoic Acid ◽

Alveolar Bone Loss ◽

Gram Negative Bacteria ◽

Gram Positive ◽

Gram Negative ◽

Gram Positive Bacteria

AbstractPeriodontitis is an inflammatory disease associated with severe alveolar bone loss and is dominantly induced by lipopolysaccharide from Gram-negative bacteria; however, the role of Gram-positive bacteria in periodontal bone resorption remains unclear. In this study, we examined the effects of lipoteichoic acid (LTA), a major cell-wall factor of Gram-positive bacteria, on the progression of inflammatory alveolar bone loss in a model of periodontitis. In coculture of mouse primary osteoblasts and bone marrow cells, LTA induced osteoclast differentiation in a dose-dependent manner. LTA enhanced the production of PGE2 accompanying the upregulation of the mRNA expression of mPGES-1, COX-2 and RANKL in osteoblasts. The addition of indomethacin effectively blocked the LTA-induced osteoclast differentiation by suppressing the production of PGE2. Using ex vivo organ cultures of mouse alveolar bone, we found that LTA induced alveolar bone resorption and that this was suppressed by indomethacin. In an experimental model of periodontitis, LTA was locally injected into the mouse lower gingiva, and we clearly detected alveolar bone destruction using 3D-μCT. We herein demonstrate a new concept indicating that Gram-positive bacteria in addition to Gram-negative bacteria are associated with the progression of periodontal bone loss.

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Incerto-thalamic modulation of fear via GABA and dopamine

Neuropsychopharmacology ◽

10.1038/s41386-021-01006-5 ◽

2021 ◽

Author(s):

Archana Venkataraman ◽

Sarah C. Hunter ◽

Maria Dhinojwala ◽

Diana Ghebrezadik ◽

JiDong Guo ◽

...

Keyword(s):

Brain Regions ◽

Zona Incerta ◽

Dependent Manner ◽

Post Traumatic Stress ◽

Functional Roles ◽

Functional Connections ◽

Optogenetic Stimulation ◽

Fear Generalization ◽

Stimulation Of

AbstractFear generalization and deficits in extinction learning are debilitating dimensions of Post-Traumatic Stress Disorder (PTSD). Most understanding of the neurobiology underlying these dimensions comes from studies of cortical and limbic brain regions. While thalamic and subthalamic regions have been implicated in modulating fear, the potential for incerto-thalamic pathways to suppress fear generalization and rescue deficits in extinction recall remains unexplored. We first used patch-clamp electrophysiology to examine functional connections between the subthalamic zona incerta and thalamic reuniens (RE). Optogenetic stimulation of GABAergic ZI → RE cell terminals in vitro induced inhibitory post-synaptic currents (IPSCs) in the RE. We then combined high-intensity discriminative auditory fear conditioning with cell-type-specific and projection-specific optogenetics in mice to assess functional roles of GABAergic ZI → RE cell projections in modulating fear generalization and extinction recall. In addition, we used a similar approach to test the possibility of fear generalization and extinction recall being modulated by a smaller subset of GABAergic ZI → RE cells, the A13 dopaminergic cell population. Optogenetic stimulation of GABAergic ZI → RE cell terminals attenuated fear generalization and enhanced extinction recall. In contrast, optogenetic stimulation of dopaminergic ZI → RE cell terminals had no effect on fear generalization but enhanced extinction recall in a dopamine receptor D1-dependent manner. Our findings shed new light on the neuroanatomy and neurochemistry of ZI-located cells that contribute to adaptive fear by increasing the precision and extinction of learned associations. In so doing, these data reveal novel neuroanatomical substrates that could be therapeutically targeted for treatment of PTSD.

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Silencing of Vangl2 attenuates the inflammation promoted by Wnt5a via MAPK and NF-κB pathway in chondrocytes

Journal of Orthopaedic Surgery and Research ◽

10.1186/s13018-021-02268-x ◽

2021 ◽

Vol 16 (1) ◽

Author(s):

Ke Zhang ◽

Zhuoying Li ◽

Yunyang Lu ◽

Linyi Xiang ◽

Jiadong Sun ◽

...

Keyword(s):

Western Blotting ◽

Planar Cell Polarity ◽

Type Ii Collagen ◽

Mapk Signaling ◽

Dependent Manner ◽

Inflammatory Microenvironment ◽

Functional Roles ◽

Protein Levels ◽

Oa Chondrocytes

Abstract Background The Wnt planar cell polarity (PCP) pathway is implicated in osteoarthritis (OA) both in animals and in humans. Van Gogh-like 2 (Vangl2) is a key PCP protein that is required for the orientation and alignment of chondrocytes in the growth plate. However, its functional roles in OA still remain undefined. Here, we explored the effects of Vangl2 on OA chondrocyte in vitro and further elucidated the molecular mechanism of silencing Vangl2 in Wnt5a-overexpressing OA chondrocytes. Methods Chondrocytes were treated with IL-1β (10 ng/mL) to simulate the inflammatory microenvironment of OA. The expression levels of Vangl2, Wnt5a, MMPs, and related proinflammatory cytokines were measured by RT-qPCR. Small interfering RNA (siRNA) of Vangl2 and the plasmid targeting Wnt5a were constructed and transfected into ATDC5 cells. Then, the functional roles of silencing Vangl2 in the OA chondrocytes were investigated by Western blotting, RT-qPCR, and immunocytochemistry (ICC). Transfected OA chondrocytes were subjected to Western blotting to analyze the relationship between Vangl2 and related signaling pathways. Results IL-1β induced the production of Vangl2, Wnt5a, and MMPs in a time-dependent manner and the significantly increased expression of Vangl2. Vangl2 silencing effectively suppressed the expression of MMP3, MMP9, MMP13, and IL-6 at both gene and protein levels and upregulated the expression of type II collagen and aggrecan. Moreover, knockdown of Vangl2 inhibited the phosphorylation of MAPK signaling molecules (P38, ERK, and JNK) and P65 in Wnt5a-overexpressing OA chondrocytes. Conclusions For the first time, we demonstrate that Vangl2 is involved in the OA process. Vangl2 silencing can notably alleviate OA progression in vitro by inhibiting the expression of MMPs and increasing the formation of the cartilage matrix and can inhibit the proinflammatory effects of Wnt5a via MAPK and NF-κB pathway. This study provides new insight into the mechanism of cartilage inflammation.

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Aspergillus nidulans wetA activates spore-specific gene expression.

Molecular and Cellular Biology ◽

10.1128/mcb.11.1.55 ◽

1991 ◽

Vol 11 (1) ◽

pp. 55-62 ◽

Cited By ~ 109

Author(s):

M A Marshall ◽

W E Timberlake

Keyword(s):

Gene Expression ◽

Cell Wall ◽

Aspergillus Nidulans ◽

Gene Activation ◽

Regulatory Function ◽

Specific Gene ◽

Coding Region ◽

Vegetative Cells ◽

Mutant Strains ◽

Late Stages

The Aspergillus nidulans wetA gene is required for synthesis of cell wall layers that make asexual spores (conidia) impermeable. In wetA mutant strains, conidia take up water and autolyze rather than undergoing the final stages of maturation. wetA is activated during conidiogenesis by sequential expression of the brlA and abaA regulatory genes. To determine whether wetA regulates expression of other sporulation-specific genes, its coding region was fused to a nutritionally regulated promoter that permits gene activation in vegetative cells (hyphae) under conditions that suppress conidiation. Expression of wetA in hyphae inhibited growth and caused excessive branching. It did not lead to activation of brlA or abaA but did cause accumulation of transcripts from genes that are normally expressed specifically during the late stages of conidiation and whose mRNAs are stored in mature spores. Thus, wetA directly or indirectly regulates expression of some spore-specific genes. At least one gene (wA), whose mRNA does not occur in spores but rather accumulates in the sporogenous phialide cells, was activated by wetA, suggesting that wetA may have a regulatory function in these cells as well as in spores. We propose that wetA is responsible for activating a set of genes whose products make up the final two conidial wall layers or direct their assembly and through this activity is responsible for acquisition of spore dormancy.

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