Varying influence of the autolysin, N-acetyl muramidase, and the cell envelope proteinase on the rate of autolysis of six commercial Lactococcus lactis cheese starter bacteria grown in milk

2000 ◽  
Vol 67 (4) ◽  
pp. 585-596 ◽  
Author(s):  
SELVARANI GOVINDASAMY-LUCEY ◽  
PRAMOD K. GOPAL ◽  
PATRICK A. SULLIVAN ◽  
CHRISTOPHER J. PILLIDGE
Keyword(s):  
Lactococcus Lactis ◽  
Cell Walls ◽  
Cell Envelope ◽  
Laboratory Strain ◽  
Proteolytic Cleavage ◽  
Zymogram Analysis ◽  
Sds Page ◽  
Derivatives Of ◽  
Free Strains

The autolysin, N-acetyl muramidase (AcmA), of six commercial Lactococcus lactis subsp. cremoris starter strains and eight Lc. lactis subsp. cremoris derivatives or plasmid-free strains was shown by renaturing SDS-PAGE (zymogram analysis) to be degraded by the cell envelope proteinase (lactocepin; EC 3.4.21.96) after growth of strains in milk at 30 °C for 72 h. Degradation of AcmA was less in starter strains and derivatives producing lactocepin I/III (intermediate specificity) than in strains producing lactocepin I. This supports previous observations on AcmA degradation in derivatives of the laboratory strain Lc. lactis subsp. cremoris MG1363 (Buist et al. Journal of Bacteriology180 5947–5953 1998). In contrast to the MG1363 derivatives, however, the extent of autolysis in milk of the commercial Lc. lactis subsp. cremoris starter strains in this study did not always correlate with lactocepin specificity and AcmA degradation. The distribution of autolysins within the cell envelope of Lc. lactis subsp. cremoris starter strains and derivatives harvested during growth in milk was compared by zymogram analysis. AcmA was found associated with cell membranes as well as cell walls and some cleavage of AcmA occurred independently of lactocepin activity. An AcmA product intermediate in size between precursor (46 kDa) and mature (41 kDa) forms of AcmA was clearly visible on zymograms, even in the absence of lactocepin I activity. These results show that autolysis of commercial Lc. lactis subsp. cremoris starter strains is not primarily determined by AcmA activity in relation to lactocepin specificity and that proteolytic cleavage of AcmA in vivo is not fully defined.

scholarly journals Mechanically Resolved Imaging of Bacteria using Expansion Microscopy

2019 ◽  
Author(s):  
Youngbin Lim ◽  
Margarita Khariton ◽  
Keara M. Lane ◽  
Anthony L. Shiver ◽  
Katharine M. Ng ◽  
...  
Keyword(s):  
Cell Walls ◽  
Pathogenic Bacteria ◽  
Cell Envelope ◽  
Grand Challenge ◽  
Bacterial Cells ◽  
Spectral Separation ◽  
Microbe Interactions ◽  
Microscopy Method ◽  
Host Microbe Interactions

AbstractImaging dense and diverse microbial communities has broad applications in basic microbiology and medicine, but remains a grand challenge due to the fact that many species adopt similar morphologies. While prior studies have relied on techniques involving spectral labeling, we have developed an expansion microscopy method (μExM) in which cells are physically expanded prior imaging and their expansion patterns depend on the structural and mechanical properties of their cell walls, which vary across species and conditions. We use this phenomenon as a quantitative and sensitive phenotypic imaging contrast orthogonal to spectral separation in order to resolve bacterial cells of different species or in distinct physiological states. Focusing on host-microbe interactions that are difficult to quantify through fluorescence alone, we demonstrate the ability of μExM to distinguish species within a dense community throughin vivoimaging of a model gut microbiota, and to sensitively detect cell-envelope damage caused by antibiotics or previously unrecognized cell-to-cell phenotypic heterogeneity among pathogenic bacteria as they infect macrophages.

scholarly journals Expression of Staphylococcus aureusClumping Factor A in Lactococcus lactis subsp.cremoris Using a New Shuttle Vector

2000 ◽  
Vol 68 (6) ◽  
pp. 3516-3522 ◽  
Author(s):  
Yok-Ai Que ◽  
Jacques-Antoine Haefliger ◽  
Patrick Francioli ◽  
Philippe Moreillon
Keyword(s):  
Lactococcus Lactis ◽  
Cell Walls ◽  
Solid Phase ◽  
Shuttle Vector ◽  
Luciferase Reporter ◽  
Reporter System ◽  
Western Blots ◽  
E Coli ◽  
Pathogenic Factors

ABSTRACT Staphylococcus aureus harbors redundant adhesins mediating tissue colonization and infection. To evaluate their intrinsic role outside of the staphylococcal background, a system was designed to express them in Lactococcus lactis subsp.cremoris 1363. This bacterium is devoid of virulence factors and has a known genetic background. A new Escherichia coli-L. lactis shuttle and expression vector was constructed for this purpose. First, the high-copy-number lactococcal plasmid pIL253 was equipped with the oriColE1 origin, generating pOri253 that could replicate in E. coli. Second, the lactococcal promoters P23 or P59 were inserted at one end of the pOri253 multicloning site. Gene expression was assessed by a luciferase reporter system. The plasmid carrying P23 (named pOri23) expressed luciferase constitutively at a level 10,000 times greater than did the P59-containing plasmid. Transcription was absent in E. coli. The staphylococcal clumping factor A (clfA) gene was cloned into pOri23 and used as a model system. Lactococci carrying pOri23-clfA produced an unaltered and functional 130-kDa ClfA protein attached to their cell walls. This was indicated both by the presence of the protein in Western blots of solubilized cell walls and by the ability of ClfA-positive lactococci to clump in the presence of plasma. ClfA-positive lactococci had clumping titers (titer of 4,112) similar to those of S. aureus Newman in soluble fibrinogen and bound equally well to solid-phase fibrinogen. These experiments provide a new way to study individual staphylococcal pathogenic factors and might complement both classical knockout mutagenesis and modern in vivo expression technology and signature tag mutagenesis.

The Anticoagulant Properties of a Modified Form of Protein S

1988 ◽  
Vol 60 (02) ◽  
pp. 298-304 ◽  
Author(s):  
C A Mitchell ◽  
S M Kelemen ◽  
H H Salem
Keyword(s):  
Monoclonal Antibody ◽  
Anticoagulant Activity ◽  
Activated Protein C ◽  
Factor Xa ◽  
Protein S ◽  
Human Neutrophil Elastase ◽  
Factor X ◽  
Sds Page

SummaryProtein S (PS) is a vitamin K-dependent anticoagulant that acts as a cofactor to activated protein C (APC). To date PS has not been shown to possess anticoagulant activity in the absence of APC.In this study, we have developed monoclonal antibody to protein S and used to purify the protein to homogeneity from plasma. Affinity purified protein S (PSM), although identical to the conventionally purified protein as judged by SDS-PAGE, had significant anticoagulant activity in the absence of APC when measured in a factor Xa recalcification time. Using SDS-PAGE we have demonstrated that prothrombin cleavage by factor X awas inhibited in the presence of PSM. Kinetic analysis of the reaction revealed that PSM competitively inhibited factor X amediated cleavage of prothrombin. PS preincubated with the monoclonal antibody, acquired similar anticoagulant properties. These results suggest that the interaction of the monoclonal antibody with PS results in an alteration in the protein exposing sites that mediate the observed anticoagulant effect. Support that the protein was altered was derived from the observation that PSM was eight fold more sensitive to cleavage by thrombin and human neutrophil elastase than conventionally purified protein S.These observations suggest that PS can be modified in vitro to a protein with APC-independent anticoagulant activity and raise the possibility that a similar alteration could occur in vivo through the binding protein S to a cellular or plasma protein.

Acyl-Enzymes as Thrombolytic Agents in Dog Models of Venous Thrombosis and Pulmonary Embolism

1984 ◽  
Vol 51 (02) ◽  
pp. 248-253 ◽  
Author(s):  
R J Dupe ◽  
P D English ◽  
R A G Smith ◽  
J Green
Keyword(s):  
Pulmonary Embolism ◽  
Side Effects ◽  
Venous Thrombosis ◽  
Active Site ◽  
Acute Pulmonary Embolism ◽  
Quantitative Model ◽  
Beagle Dog ◽  
Thrombosis Model ◽  
Derivatives Of

SummaryA quantitative model of venous thrombosis in the beagle dog is described. The model was adapted to permit ageing of isolated experimental clots in vivo. A model of acute pulmonary embolism in this species is also described. In the venous thrombosis model, infusion of streptokinase (SK) or SK-activated human plasmin gave significant lysis but bolus doses of SK. plasmin complex were ineffective. Active site anisoylated derivatives of SK. plasminogen complex, SK-activated plasmin and activator-free plasmin were all active when given as bolus doses in both models. At lytic doses, the acyl-enzymes caused fewer side-effects attributable to plasminaemia than the corresponding unmodified enzymes.

Negative cross resistance of Spodoptera litura Fabricius population of tomato to newer molecule spinetoram

ENTOMON ◽  
2019 ◽  
Vol 44 (2) ◽  
pp. 127-132
Author(s):  
M. Visnupriya ◽  
N. Muthukrishnan
Keyword(s):  
Spodoptera Litura ◽  
Laboratory Strain ◽  
Field Population ◽  
Resistance Ratio ◽  
Cross Resistance ◽  
In Vivo Toxicity

Field population of Spodoptera litura from tomato ( resistant to the majority of the conventional insecticide molecules) were subjected to the in vivo toxicity of spinetoram 12 SC to assess whether cross resistance exists or not. Untreated larvae of both field and laboratory strains showed no mortality during 48 hours of feeding. After 48 hours of feeding on spinetoram 12 SC treated leaves, LC50s of field larvae were 0.28, 0.93, 3.71 and 7.11 ppm for the 2nd, 3rd, 4th and 5th instars of S. litura respectively. However, in the laboratory strain these values were 1.12, 5.86, 36.72 and 91.55 ppm for 2nd, 3rd, 4th and 5th instars of S. litura respectively. Resistance ratio was 0.25, 0.16, 0.10 and 0.08 for the 2nd instar up to the 5th instar of S. litura.

Synthesis and In Vivo Antimalarial Activity of Novel Derivatives of 6- Mercaptopurine

2013 ◽  
Vol 10 (8) ◽  
pp. 741-747 ◽  
Author(s):  
Roberta Soares ◽  
Roberta Corrales ◽  
Fernanda Lopes ◽  
Marcio Alves ◽  
Adilson Silva ◽  
...  
Keyword(s):  
Antimalarial Activity ◽  
Derivatives Of

Derivatives of Deoxypodophyllotoxin Induce Apoptosis Through Bcl-2/Bax Proteins Expression

2020 ◽  
Vol 20 ◽  
Author(s):  
Ya-Nan Li ◽  
Ni Ning ◽  
Lei Song ◽  
Yun Geng ◽  
Jun-Ting Fan ◽  
...  
Keyword(s):  
Annexin V ◽  
Mtt Method ◽  
Anthriscus Sylvestris ◽  
Anti Tumor Activity ◽  
Derivatives Of ◽  
Toxicity In Vitro ◽  
Ht 29 ◽  
Mcf 7

Background: Deoxypodophyllotoxin, isolated from theTraditional Chinese Medicine Anthriscus sylvestris, is well-known because of its significant antitumor activity with strong toxicity in vitro and in vivo. Objective: In this article, we synthesized a series of deoxypodophyllotoxin derivatives, and evaluated their antitumor effectiveness.Methods:The anti tumor activity of deoxypodophyllotoxin derivatives was investigated by the MTT method. Apoptosis percentage was measured by flow cytometer analysis using Annexin-V-FITC. Results: The derivatives revealed obvious cytotoxicity in the MTT assay by decreasing the number of late cancer cells. The decrease of Bcl-2/Bax could be observed in MCF-7, HepG2, HT-29 andMG-63 using Annexin V-FITC. The ratio of Bcl-2/Bax in the administration group was decreased, which was determined by the ELISA kit. Conclusion: The derivatives of deoxypodophyllotoxin could induce apoptosis in tumor cell lines by influencing Bcl-2/Bax.

Some 1-substitution derivatives of 4-aryl-2,3-dihalogeno-1-naphthols

1984 ◽  
Vol 49 (1) ◽  
pp. 110-121 ◽  
Author(s):  
Jiří Křepelka ◽  
Drahuše Vlčková ◽  
Milan Mělka
Keyword(s):  
Thionyl Chloride ◽  
Oxirane Ring ◽  
Secondary Amines ◽  
Two Phase ◽  
Lytic Effect ◽  
Primary And Secondary Amines ◽  
Phase Medium ◽  
Chloro Derivatives ◽  
Derivatives Of

Alkylation of derivatives of 4-aryl-1-naphthols (I-V) by 2,3-epoxypropyl chloride in methanolic sodium hydroxide gave epoxy derivatives VI, VIII, IX, XI and XII, apart from products of cleavage of the oxirane ring, VII and X. Analogous alkylation of compounds I, IV and V by 2-(N,N-diethylamino)ethyl chloride hydrochloride in a two-phase medium afforded basic ethers XIII to XV. The cleavage of the oxirane ring in compound VI by the action of primary and secondary amines, piperidine and substituted piperazines led to compounds XVI-XXIV. Reaction of thionyl chloride with compounds XXI, XXII and XXIV gave chloro derivatives XXV-XXVII.Exposure of compound XXII to 4-methylbenzenesulfonyl chloride produced compound XXVIII, retaining the secondary alcoholic group. In an antineoplastic screening in vivo none of the compounds prepared had an appreciable activity. Compound XVII, being an analogue of propranolol, was used in the test of isoproterenolic tachycardia, and showed a beta-lytic effect comparable with that of propranol.

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