Large chromosomal inversion correlated with spectinomycin resistance in Lactococcus lactis subsp. lactis bv. diacetylactis S50

2008 ◽  
Vol 54 (2) ◽  
pp. 143-149 ◽  
Author(s):  
Milan Kojic ◽  
Branko Jovcic ◽  
Jelena Begovic ◽  
Djordje Fira ◽  
Ljubisa Topisirovic
Keyword(s):  
Lactococcus Lactis ◽  
Chromosomal Inversion ◽  
High Concentration ◽  
Lactococcus Lactis Subsp ◽  
Ribosomal Operons ◽  
One Step ◽  
Resistant Mutants ◽  
High Concentrations ◽  
Derivatives Of

A large chromosomal inversion that confers resistance to high concentrations of the antibiotic spectinomycin in Lactococcus lactis subsp. lactis bv. diacetylactis S50 was identified by pulsed field gel electrophoresis. The same type of inversion was identified in 4 independent experiments and in 4 different derivatives of strain S50, indicating the same position and the same mechanism of recombination as a response to antibiotic selective pressure in all derivatives. An analysis of ribosomal operons in strain S50 and mutants revealed that ribosomal operons are not endpoints of the recombination. Spectinomycin-resistant mutants appeared in a population of S50 derivatives at a high frequency of 2 × 10−7. These spectinomycin-resistant mutants were not able to compete successfully with the wild-type strain during 25 generations (48 h) of co-culture in vitro, indicating that inversion had a significant fitness cost. Results demonstrate that as a mechanism of genome plasticity, inversion can be directly involved in one-step development of the adaptation to a high concentration of spectinomycin.

The Effects of Shock Vancomycin Concentrations on the Formation of Heteroresistance in Staphylococcus aureus

2020 ◽  
Vol 65 (9-10) ◽  
pp. 3-7
Author(s):  
V. V. Gostev ◽  
Yu. V. Sopova ◽  
O. S. Kalinogorskaya ◽  
M. E. Velizhanina ◽  
I. V. Lazareva ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
In Vitro Selection ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
High Concentration ◽  
Short Term ◽  
High Concentrations ◽  
Selection Of ◽  
Selection Of Resistance ◽  
Test Cultures

Glycopeptides are the basis of the treatment of infections caused by MRSA (Methicillin-Resistant Staphylococcus aureus). Previously, it was demonstrated that antibiotic tolerant phenotypes are formed during selection of resistance under the influence of high concentrations of antibiotics. The present study uses a similar in vitro selection model with vancomycin. Clinical isolates of MRSA belonging to genetic lines ST8 and ST239, as well as the MSSA (ATCC29213) strain, were included in the experiment. Test isolates were incubated for five hours in a medium with a high concentration of vancomycin (50 μg/ml). Test cultures were grown on the medium without antibiotic for 18 hours after each exposure. A total of ten exposure cycles were performed. Vancomycin was characterized by bacteriostatic action; the proportion of surviving cells after exposure was 70–100%. After selection, there was a slight increase in the MIC to vancomycin (MIC 2 μg/ml), teicoplanin (MIC 1.5–3 μg/ml) and daptomycin (MIC 0.25–2 μg/ml). According to the results of PAP analysis, all strains showed an increase in the area under curve depending on the concentration of vancomycin after selection, while a heteroresistant phenotype (with PAP/AUC 0.9) was detected in three isolates. All isolates showed walK mutations (T188S, D235N, E261V, V380I, and G223D). Exposure to short-term shock concentrations of vancomycin promotes the formation of heteroresistance in both MRSA and MSSA. Formation of VISA phenotypes is possible during therapy with vancomycin.

scholarly journals Association of beta-cytoplasmic actin with high concentrations of acetylcholine receptor (AChR) in normal and anti-AChR-treated primary rat muscle cultures.

1984 ◽  
Vol 32 (9) ◽  
pp. 973-981 ◽  
Author(s):  
B W Lubit
Keyword(s):  
Acetylcholine Receptor ◽  
Acetylcholine Receptors ◽  
Neuromuscular Junctions ◽  
Morphological Changes ◽  
Muscle Cells ◽  
High Concentration ◽  
Rat Muscle ◽  
Cytoplasmic Actin ◽  
High Concentrations

Previous immunocytochemical studies in which an antibody specific for mammalian cytoplasmic actin was used showed that a high concentration of cytoplasmic actin exists at neuromuscular junctions of rat muscle fibers such that the distribution of actin corresponded exactly to that of the acetylcholine receptors. Although clusters of acetylcholine receptors also are present in noninnervated rat and chick muscle cells grown in vitro, neither the mechanism for the formation and maintenance of these clusters nor the relationship of these clusters to the high density of acetylcholine receptors at the neuromuscular junction in vivo are known. In the present study, a relationship between beta-cytoplasmic actin and acetylcholine receptors in vitro has been demonstrated immunocytochemically using an antibody specific for the beta-form of cytoplasmic actin. Networks of cytoplasmic actin-containing filaments were found in discrete regions of the myotube membrane that also contained high concentrations of acetylcholine receptors; such high concentrations of acetylcholine receptors have been described in regions of membrane-substrate contact. Moreover, when primary rat myotubes were exposed to human myasthenic serum, gross morphological changes, accompanied by an apparent rearrangement of the cytoplasmic actin-containing cytoskeleton, were produced. Although whether the distribution of cytoplasmic actin-containing structures was influenced by the organization of acetylcholine receptor or vice versa cannot be determined from these studies, these findings suggest that in primary rat muscle cells grown in vitro, acetylcholine receptors and beta-cytoplasmic actin-containing structures may be somehow connected.

Leakage of Endotoxins through the Endotoxin Retentive Filter: An in vitro Study

2022 ◽  
pp. 1-9
Author(s):  
Hiroshi Nozaki ◽  
Yoshihiro Tange ◽  
Yoji Inada ◽  
Takashi Uchino ◽  
Nakanobu Azuma
Keyword(s):  
Sodium Hypochlorite ◽  
Peracetic Acid ◽  
In Vitro Study ◽  
Dialysis Fluid ◽  
High Concentration ◽  
Membrane Pores ◽  
Polyether Sulfone ◽  
Repeated Use ◽  
High Concentrations

<b><i>Introduction:</i></b> Ultrapurification of dialysis fluid has enabled highly efficient dialysis treatments. Online hemodiafiltration is one such treatment that uses a purified dialysis fluid as a supplemental fluid. In this method, an endotoxin retentive filter (ETRF) is used in the final step of dialysis fluid purification, with the aim of preventing leakage of endotoxins. Sodium hypochlorite and peracetic acid are used as disinfecting agents for the dialysis fluid pipes containing the ETRF; however, the effects of these agents on ETRF membrane pores have not been fully clarified. <b><i>Methods:</i></b> Water permeability (flux) and endotoxin permeability were assessed in 3 types of ETRFs made with different membrane materials: polyester polymer alloy (PEPA), polyether sulfone (PES), and polysulfone (PS). High-concentration sodium hypochlorite and 2 types of peracetic acid were used as disinfecting agents, and the changes in flux and the endotoxin sieving coefficient (SC) were measured. <b><i>Results:</i></b> After repeated use of high concentrations of sodium hypochlorite and peracetic acid, the PEPA and PES ETRFs did not permit passage of endotoxins, regardless of their flux. However, in the PS ETRF, the flux and endotoxin SC increased with the number of cleaning cycles. No differences were observed according to the concentration of peracetic acid disinfecting agents. <b><i>Conclusion:</i></b> PEPA and PES ETRFs completely prevent endotoxin leakage and can be disinfected at concentrations higher than the conventionally recommended concentration without affecting pore expansion. Even new PS ETRFs have low levels of endotoxin leakage, which increase after disinfection cycles using sodium hypochlorite and peracetic acid.

scholarly journals Complete Genome Sequence of Lactococcus lactis subsp. lactis Strain 14B4, Which Inhibits the Growth of Salmonella enterica Serotype Poona In Vitro

2018 ◽  
Vol 7 (19) ◽  
Author(s):  
Thao D. Tran ◽  
Steven Huynh ◽  
Craig T. Parker ◽  
Ruyang Han ◽  
Robert Hnasko ◽  
...  
Keyword(s):  
Lactococcus Lactis ◽  
Genome Sequence ◽  
Complete Genome Sequence ◽  
Salmonella Enterica ◽  
Complete Genome ◽  
Northern California ◽  
Content Type ◽  
Lactococcus Lactis Subsp ◽  
Lactis Strain

We present here the complete genome sequence of Lactococcus lactis strain 14B4, isolated from almond drupes in northern California. This strain was observed to inhibit the growth of Salmonella enterica serotype Poona strain RM3363 in vitro.

The antibacterial activity expressed in vitro and in vivo by Lactococcus lactis subsp. lactis CNRZ 1427 against Salmonella sp.

2015 ◽  
Vol 4 (5) ◽  
pp. 240-246
Author(s):  
Menad Najett ◽  
Chougrani Fadelaa ◽  
Moghtet Snoussi ◽  
Cheriguene Abderrahim
Keyword(s):  
Antibacterial Activity ◽  
Lactococcus Lactis ◽  
Bile Salts ◽  
Therapeutic Agent ◽  
Lactococcus Lactis Subsp ◽  
Beneficial Effects ◽  
Gastrointestinal Conditions ◽  
Therapeutic Possibilities

  The present study focused on the beneficial effects of Lactococcus lactis subsp lactis CNRZ 1427 with possible use as a therapeutic agent against Sal-monella sp.; also we have proposed different therapeutic possibilities of our situation against a pathogen Salmonella sp. We have conducted two tests In Vitro and In Vivo; where it is noted that treatment in the presence of this lac-tic strain is effective since it causes a remarkable decrease of the pathogen agent. At the end, the effectiveness of this lactic strain was confirmed by testing for resistance to gastrointestinal conditions (pH, bile salts and diges-tive enzymes).

scholarly journals In vitro assessment of hypocholesterolemic activity of Lactococcus lactis subsp. lactis

2019 ◽  
Vol 43 (1) ◽  
Author(s):  
Mohamed G. Shehata ◽  
Malak A. El-Sahn ◽  
Sobhy A. El Sohaimy ◽  
Mohamed M. Youssef
Keyword(s):  
Lactococcus Lactis ◽  
Lactococcus Lactis Subsp ◽  
In Vitro Assessment

scholarly journals The Swallowing Characteristics of Thickeners, Jellies and Yoghurt Observed Using an In Vitro Model

Dysphagia ◽  
2019 ◽  
Vol 35 (4) ◽  
pp. 685-695 ◽  
Author(s):  
Simmi Patel ◽  
William J. McAuley ◽  
Michael T. Cook ◽  
Yi Sun ◽  
Shaheen Hamdy ◽  
...  
Keyword(s):  
Transit Time ◽  
Mechanical Model ◽  
Xanthan Gum ◽  
In Vitro Model ◽  
High Concentration ◽  
High Concentrations ◽  
Vitro Model ◽  
Thickening Agents

Abstract Drinks and foods may be thickened to improve swallowing safety for dysphagia patients, but the resultant consistencies are not always palatable. Characterising alternative appetising foods is an important task. The study aims to characterise the in vitro swallowing behaviour of specifically formulated thickened dysphagia fluids containing xanthan gum and/or starch with standard jellies and yoghurt using a validated mechanical model, the “Cambridge Throat”. Observing from the side, the model throat can follow an experimental oral transit time (in vitro-OTT) and a bolus length (BL) at the juncture of the pharynx and larynx, to assess the velocity and cohesion of bolus flow. Our results showed that higher thickener concentration produced longer in vitro-OTT and shorter BL. At high concentration (spoon-thick), fluids thickened with starch-based thickener showed significantly longer in vitro-OTT than when xanthan gum-based thickener was used (84.5 s ± 34.5 s and 5.5 s ± 1.6 s, respectively, p < 0.05). In contrast, at low concentration (nectar-like), fluids containing xanthan gum-based thickener demonstrated shorter BL than those of starch-based thickener (6.4 mm ± 0.5 mm and 8.2 mm ± 0.8 mm, respectively, p < 0.05). The jellies and yoghurt had comparable in vitro-OTT and BL to thickeners at high concentrations (honey-like and spoon-thick), indicating similar swallowing characteristics. The in vitro results showed correlation with published in vivo data though the limitations of applying the in vitro swallowing test for dysphagia studies were noted. These findings contribute useful information for designing new thickening agents and selecting alternative and palatable safe-to-swallow foods.

High in vitro shoot proliferation in the apple cultivar Jonagold induced by benzyladenine analogues

2002 ◽  
Vol 50 (2) ◽  
pp. 191-195 ◽  
Author(s):  
K. Magyar-Tábori ◽  
J. Dobránszki ◽  
E. Jámbor-Benczúr
Keyword(s):  
Shoot Proliferation ◽  
Shoot Multiplication ◽  
Shoot Length ◽  
Multiplication Rate ◽  
Apple Cultivar ◽  
High Concentration ◽  
Suppression Effect ◽  
High Concentrations ◽  
In Vitro Shoot Proliferation

The in vitro shoot multiplication of apple cv. Jonagold was tested on media containing benzyladenine, benzyladenine riboside or meta-topolin in different concentrations (from 0.0 to 5.0 mg l-1). The optimal concentration for the best multiplication varied according to the type of cytokinin. The highest multiplication rate (on average 6.9 and 5.9 new shoots per explant) was achieved using 5.0 mg l-1 meta-topolin or 2.0 mg l-1 benzyladenine riboside. The longest shoots were formed on media containing benzyladenine riboside at a concentration of 0.5 mg l-1. The length of newly developed shoots was strongly suppressed by high concentrations of different cytokinins, but the suppression effect of a high concentration of meta-topolin on shoot length was less than that of benzyladenine or benzyladenine riboside. In this study meta-topolin and benzyladenine riboside proved to be effective cytokinins to induce adequate shoot proliferation, while benzyladenine was the least active cytokinin

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