scholarly journals Xenorhabdus bovienii strain jolietti uses a type 6 secretion system to kill closely related Xenorhabdus strains

2020 ◽  
Vol 96 (8) ◽  
Author(s):  
Rebecca M Kochanowsky ◽  
Christine Bradshaw ◽  
Isabel Forlastro ◽  
S Patricia Stock
Keyword(s):  
Life Cycle ◽  
Growth Conditions ◽  
Body Cavity ◽  
Structural Protein ◽  
Secretion Systems ◽  
Insecticidal Toxins ◽  
Wide Range ◽  
Specific Proteins ◽  
Redundant Role

ABSTRACT Xenorhabdus bovienii strain jolietti (XBJ) is a Gram-negative bacterium that interacts with several organisms as a part of its life cycle. It is a beneficial symbiont of nematodes, a potent pathogen of a wide range of soil-dwelling insects and also has the ability to kill soil- and insect-associated microbes. Entomopathogenic Steinernema nematodes vector XBJ into insects, releasing the bacteria into the insect body cavity. There, XBJ produce a variety of insecticidal toxins and antimicrobials. XBJ's genome also encodes two separate Type Six Secretion Systems (T6SSs), structures that allow bacteria to inject specific proteins directly into other cells, but their roles in the XBJ life cycle are mostly unknown. To probe the function of these T6SSs, we generated mutant strains lacking the key structural protein Hcp from each T6SS and assessed phenotypes related to different parts of XBJ's life cycle. Here we demonstrate that one of the T6SSs is more highly expressed in in vitro growth conditions and has antibacterial activity against other Xenorhabdus strains, and that the two T6SSs have a redundant role in biofilm formation.

Molecular Docking of Azithromycin, Ritonavir, Lopinavir, Oseltamivir, Ivermectin and Heparin Interacting with Coronavirus Disease 2019 Main and Severe Acute Respiratory Syndrome Coronavirus-2 3C-Like Proteases

2021 ◽  
Vol 21 (4) ◽  
pp. 2075-2089
Author(s):  
Tiago da Silva Arouche ◽  
Anderson Yuri Martins ◽  
Teodorico de Castro Ramalho ◽  
Raul Nunes Carvalho Júnior ◽  
Fabio Luiz Paranhos Costa ◽  
...  
Keyword(s):  
Life Cycle ◽  
Viral Life Cycle ◽  
Stable Complex ◽  
Viral Agent ◽  
Main Protease ◽  
Wide Range ◽  
Approved Drugs ◽  
Pharmacologically Active ◽  
3Cl Protease

In the current pandemic situation raised due to COVID-19, drug reuse is emerging as the first line of treatment. The viral agent that causes this highly contagious disease and the acute respiratory syndrome coronavirus (SARS-CoV) share high nucleotide similarity. Therefore, it is structurally expected that many existing viral targets are similar to the first SARS-CoV, probably being inhibited by the same compounds. Here, we selected two viral proteins based on their vital role in the viral life cycle: Structure of the main protease SARS-CoV-2 and the structural base of the SARS-CoV-2 protease 3CL, both supporting the entry of the virus into the human host. The approved drugs used were azithromycin, ritonavir, lopinavir, oseltamivir, ivermectin and heparin, which are emerging as promising agents in the fight against COVID-19. Our hypothesis behind molecular coupling studies is to determine the binding affinities of these drugs and to identify the main amino acid residues that play a fundamental role in their mechanism of action. Additional studies on a wide range of FDA-approved drugs, including a few more protein targets, molecular dynamics studies, in vitro and biological in vivo evaluation are needed to identify combination therapy targeted at various stages of the viral life cycle. In our experiment in silico, based mainly on the molecular coupling approach, we investigated six different types of pharmacologically active drugs, aiming at their potential application alone or in combination with the reuse of drugs. The ligands showed stable conformations when analyzing the affinity energy in both proteases: ivermectin forming a stable complex with the two proteases with values −8.727 kcal/mol for Main Protease and −9.784 kcal/mol for protease 3CL, Heparin with values of −7.647 kcal/mol for the Main protease and −7.737 kcal/mol for the 3CL protease. Both conform to the catalytic site of the proteases. Our studies can provide an insight into the possible interactions between ligands and receptors, through better conformation. The ligands ivermectin, heparin and ritonavir showed stable conformations. Our in-silica docking data shows that the drugs we have identified can bind to the binding compartment of both proteases, this strongly supports our hypothesis that the development of a single antiviral agent targeting Main protease, or 3CL protease, or an agent used in combination with other potential therapies, it could provide an effective line of defense against diseases associated with coronaviruses.

Df31 is a novel nuclear protein involved in chromatin structure in Drosophila melanogaster

2001 ◽  
Vol 114 (1) ◽  
pp. 37-47 ◽  
Author(s):  
G. Crevel ◽  
H. Huikeshoven ◽  
S. Cotterill
Keyword(s):  
Cell Types ◽  
Drosophila Embryo ◽  
Cell Fractionation ◽  
General Function ◽  
Structural Protein ◽  
Chromosomal Structure ◽  
Binding Characteristics ◽  
Wide Range ◽  
Cellular Dna

We originally isolated the Df31 protein from Drosophila embryo extracts as a factor which could decondense Xenopus sperm, by removing the sperm specific proteins and interacting with histones to facilitate their loading onto DNA. We now believe that this protein has a more general function in cellular DNA metabolism. The Df31 gene encodes a very hydrophilic protein with a predicted molecular mass of 18.5 kDa. Immunostaining showed that Df31 was present in a wide range of cell types throughout differentiation and in both dividing and non-dividing cells. In all cases the protein is present in large amounts, comparable with the level of nucleosomes. Injection of antisense oligonucleotides to lower the level of Df31 in embryos caused severe disruption of the nuclear structure. Large irregular clumps of DNA were formed, and in most cases the amount of DNA associated with each clump was more than that found in a normal nucleus. Immunofluorescence, cell fractionation, and formaldehyde cross-linking show that Df31 is associated with chromatin and that a significant fraction of it binds very tightly. It also shows the same binding characteristics when loaded onto chromatin in vitro. Chromatin fractionation shows that Df31 is tightly associated with nucleosomes, preferentially with oligonucleosomes. Despite this no differences were observed in the properties of nucleosomes loaded in the in vitro system in the presence and absence of Df31. These results suggest that Df31 has a role in chromosomal structure, most likely acting as a structural protein at levels of folding higher than that of nucleosomes.

scholarly journals Defining the core essential genome ofPseudomonas aeruginosa

2019 ◽  
Vol 116 (20) ◽  
pp. 10072-10080 ◽  
Author(s):  
Bradley E. Poulsen ◽  
Rui Yang ◽  
Anne E. Clatworthy ◽  
Tiantian White ◽  
Sarah J. Osmulski ◽  
...  
Keyword(s):  
Bacterial Species ◽  
Growth Conditions ◽  
Essential Genes ◽  
The Core ◽  
Transposon Insertion ◽  
Wide Range ◽  
Transposon Insertion Sequencing ◽  
Antibiotic Discovery

Genomics offered the promise of transforming antibiotic discovery by revealing many new essential genes as good targets, but the results fell short of the promise. While numerous factors contributed to the disappointing yield, one factor was that essential genes for a bacterial species were often defined based on a single or limited number of strains grown under a single or limited number of in vitro laboratory conditions. In fact, the essentiality of a gene can depend on both the genetic background and growth condition. We thus developed a strategy for more rigorously defining the core essential genome of a bacterial species by studying many pathogen strains and growth conditions. We assessed how many strains must be examined to converge on a set of core essential genes for a species. We used transposon insertion sequencing (Tn-Seq) to define essential genes in nine strains ofPseudomonas aeruginosaon five different media and developed a statistical model,FiTnEss, to classify genes as essential versus nonessential across all strain–medium combinations. We defined a set of 321 core essential genes, representing 6.6% of the genome. We determined that analysis of four strains was typically sufficient inP. aeruginosato converge on a set of core essential genes likely to be essential across the species across a wide range of conditions relevant to in vivo infection, and thus to represent attractive targets for novel drug discovery.

scholarly journals Mycobacterial Esx-3 Requires Multiple Components for Iron Acquisition

mBio ◽  
2014 ◽  
Vol 5 (3) ◽  
Author(s):  
M. Sloan Siegrist ◽  
Magnus Steigedal ◽  
Rushdy Ahmad ◽  
Alka Mehra ◽  
Marte S. Dragset ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Iron Acquisition ◽  
Multiple Reaction Monitoring ◽  
Protein Export ◽  
Secretion Systems ◽  
Experimental Conditions ◽  
Content Type ◽  
Type Vii Secretion ◽  
Wide Range

ABSTRACT The type VII secretion systems are conserved across mycobacterial species and in many Gram-positive bacteria. While the well-characterized Esx-1 pathway is required for the virulence of pathogenic mycobacteria and conjugation in the model organism Mycobacterium smegmatis, Esx-3 contributes to mycobactin-mediated iron acquisition in these bacteria. Here we show that several Esx-3 components are individually required for function under low-iron conditions but that at least one, the membrane-bound protease MycP3 of M. smegmatis, is partially expendable. All of the esx-3 mutants tested, including the ΔmycP 3ms mutant, failed to export the native Esx-3 substrates EsxH ms and EsxG ms to quantifiable levels, as determined by targeted mass spectrometry. Although we were able to restore low-iron growth to the esx-3 mutants by genetic complementation, we found a wide range of complementation levels for protein export. Indeed, minute quantities of extracellular EsxH ms and EsxG ms were sufficient for iron acquisition under our experimental conditions. The apparent separation of Esx-3 function in iron acquisition from robust EsxG ms and EsxH ms secretion in the ΔmycP 3ms mutant and in some of the complemented esx-3 mutants compels reexamination of the structure-function relationships for type VII secretion systems. IMPORTANCE Mycobacteria have several paralogous type VII secretion systems, Esx-1 through Esx-5. Whereas Esx-1 is required for pathogenic mycobacteria to grow within an infected host, Esx-3 is essential for growth in vitro. We and others have shown that Esx-3 is required for siderophore-mediated iron acquisition. In this work, we identify individual Esx-3 components that contribute to this process. As in the Esx-1 system, most mutations that abolish Esx-3 protein export also disrupt its function. Unexpectedly, however, ultrasensitive quantitation of Esx-3 secretion by multiple-reaction-monitoring mass spectrometry (MRM-MS) revealed that very low levels of export were sufficient for iron acquisition under similar conditions. Although protein export clearly contributes to type VII function, the relationship is not absolute.

Ecology of anti-microbials produced by bacterial associates ofSteinernema carpocapsaeandHeterorhabditis bacteriophora

Parasitology ◽  
1996 ◽  
Vol 112 (6) ◽  
pp. 545-552 ◽  
Author(s):  
J. Jarosz
Keyword(s):  
Life Cycle ◽  
Galleria Mellonella ◽  
Early Stage ◽  
Bacterial Activity ◽  
Wide Range ◽  
Antibiotic Compounds ◽  
Antibiotic Inhibition ◽  
Limited Spectrum ◽  
Primary Form

SUMMARYBased on the ability of bacterial associates of entomopathogenic nematodes to produce antibiotic compounds on artificial media, it has been commonly accepted thatXenorhabdussp. andPhotorhabdussp. inhibit a wide range of invading microorganisms in insects infected withSteinernemaspp. orHeterorhabditisspp. Therefore, the question of whether antibiotic compounds produced by the primary form of bacterial symbionts associated mutualistically withS. carpocapsaeandH. bacteriophoraexplain why insect carcasses do not putrefy but provide nutritional requirements for insect parasitic rhabditoid nematodes to complete their life-cycle was examined. Laboratory bioassays of anti-bacterial activity on nutrient agar and during parasitism in larvae ofGalleria mellonellahave confirmed earlier observations thatin vitrocolonies of the primary form ofX. nematophilusandP. luminescensproduced agar-diffusible antibiotic compounds of a broad spectrum of anti-bacterial activity; their role in parasitism seems doubtful, however. This hypothesis is supported by a low antibiotic potency of a limited spectrum of anti-bacterial activity throughout the life-cycle of the parasites, principally inGalleriainfected withS. carpocapsae. Since the lack of putrefaction cannot be explained simply by antibiotic inhibition of contaminating bacterial microflora, other competition mechanisms must be operating in parasitized insects. I postulated that a rapid and massive colonization of the insect body by nematophilic bacteria creates unfavourable conditions for the growth and multiplication of bacterial (proteolytic) contaminators making the insect carcass decay-resistant. In the case ofH. bacteriophora, low antibiotic activity at an early stage of parasitism could support the colonization byP. luminescensof the host.

scholarly journals Tree Growth Conditions Are Demanded When Optimal, Are Unwanted When Limited, but When Are They Suboptimal?

Plants ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 1943
Author(s):  
Claudia Cocozza ◽  
Maria Laura Traversi ◽  
Alessio Giovannelli
Keyword(s):  
Woody Species ◽  
Growth Conditions ◽  
Dose Effect ◽  
Climate Projections ◽  
Natural Conditions ◽  
Complex Interactions ◽  
Recent Climate ◽  
Wide Range ◽  
Definition Of

The recent climate projections predict that the intensity and frequency of extreme events will increase as a result of overall increasing mean temperature and reduced precipitations in the temperate regions of the Northern Hemisphere. How these changes will influence the harshness of the environment and the performances of trees growing under natural conditions remains an open question. In this commentary article, we would like to look at the concept of suboptimal growth conditions, widening its application from the traditional in vitro manipulation to trees growing in open air, addressing the main limitations and strengths of the upscaling results from cell to tree. We believe that the traditional single dose–effect approach is not suitable to explain the complex interactions between genotype and environment, occurring in open field or forest stands, where the intensity and frequency of the events are uncontrolled and unpredictable. As forests provide a wide range of ecosystem services, new parameters should be considered in the definition of the response thresholds in addition to growth. Thus, within this Special Issue, we stimulate the discussion over the development of new approaches and technologies that are able to define suitable threshold responses of trees under suboptimal natural conditions, with the aim to furnish new insights on the acclimation and adaptation processes in woody species under global change.

scholarly journals Studies on the Life Cycle of Some New Zealand Anisakidae (Nematoda)

2021 ◽  
Author(s):  
◽  
Rosemary Jennifer Hurst
Keyword(s):  
Life Cycle ◽  
New Zealand ◽  
Body Cavity ◽  
The Body ◽  
In Vitro Cultivation ◽  
Free Living ◽  
Larval Stages ◽  
Factors Influencing ◽  
Phocarctos Hookeri

<p>The life cycle of Anisakis simplex in New Zealand waters is described from observations on the morphology, distribution and behaviour of free-living and parasitic stages. Comparison with the life cyles of two other anisakids, Phocanema decipiens Myers 1959 and Thynnascaris adunca Rudolphi 1802 shows differences in distribution, degrees of host specificity, the status of invertebrate hosts, the factors influencing infestation levels of teleost hosts, and the location and pathological effects of infestation. Larval stages occurring in intermediate and paratenic hosts were identified by comparison of larval and adult morphometrics. A. simplex larvae were also positively identified by in vitro cultivation through to adults. Some morphometric variations compared to overseas descriptions are apparent. The ventriculus of A. simplex larvae is shorter relative to body length and the intestinal caecum of P. decipiens is longer relative to ventriculus length. Egg and free-living larval stages were obtained from in vitro cultivation of (A. simplex) and collection of eggs from mature adults from definitive hosts (T. adunca). Eggs of P. decipiens were not obtained. Eggs of A. simplex and T. adunca hatch in 8-11 days at 15 [degrees] C. A. simplex eggs hatch in 6 days at a temperature of 22 [degrees] C and did not hatch in 16 days at 10 [degrees] C. Eggs and free-living stage III larvae of A. simplex and T. adunca are similar in morphology with little differentiation of internal structures. Examination of the stomach contents of pelagic fish infested with anisakids indicated that possible intermediate hosts of A. simplex are the euphausiid Nyctiphanes australis and the decapod Munida gregaria. Possible hosts of T. adunca and M. gregaria are a wide variety of smaller zooplanktonic groups, e.g. decapod larvae and copepods. Larvae of A. simplex were found in one of 8850 N. australis; larvae of T. adunca were found in 69 of 3999 chaetognaths (Sagitta spp.) a medusa and a decapod larva. These larvae are morphologically similar to Stage III larvae from teleosts. No anisakids were found in 3956 Euphausia spp., 1147 M. gregaria and 740 prawns. Twenty five T. adunca larvae and adults were found in 818 freshly eaten M. gregaria in teleost stomachs, indicating that this invertebrate may act as a paratenic and a definitive host. Experimental infection of N. australis and M. gregaria with stage II larvae of A. simplex and T. adunca was unsuccessful. The location of anisakid infestation in three pelagic teleost species, Thyrsites atun, Trachurus novaezelandiae and Trachurus declivis is described. A. simplex larvae are found mainly in the body cavity of all species, at the posterior end of the stomach, with less than one percent occurring in the musculature. Distribution of A. simplex larvae does not change with increasing size of the host or increasing total worm burden. Thyrsites atun have a higher proportion of larvae in the stomach wall (8-13%) compared to Trachurus spp. (< 4%). T. adunca larvae are found infrequently in the body cavity of all three species, on the pyloric caeca and in the stomach wall. Adults and larvae of T. adunca are found more commonly in the alimentary canal, indicating that these teleosts are more important as definitive hosts in the life cycle of this anisakid. P. decipiens larvae are found only in Thyrsites atun and occur mainly in the muscles (98.5%). No quantitative pathogenic effects of anisakid infestation on these teleosts hosts were detected. The main factors influencing the infestation of the three teleost species are age of the host, locality and season. Sex of the host and depth (over the continental shelf, 0-250 m) are not important. A. simplex infestation increased with age in all host species examined, and was higher in Trachurus declivis from the southern-most locality, suggesting the existence of at least two distinct populations of this species. Significant differences in infestation of Thyrsites atun with P. decipiens suggests that this anisakid may be more common in southern localities also. The infestation of Thyrsites atun by larval and adult T. adunca in the alimentary canal is most influenced by season and closely related to diet. Nematode samples were obtained from the marine mammals Arctocephalus forsteri, Kogia breviceps and Phocarctos hookeri. Adult A. simplex were recorded from A. forsteri (a new host record) and Kogia breviceps; preadults from Phocarctos hookeri. Adult P. decipiens were recorded from Phocarctos hookeri; preadults from Arctocephalus forsteri and K. breviceps. Other anisakids found were Anisakis physeteris (Baylis 1923), Contracaecum osculatum Rudolphi 1802 and Pseudoterranova kogiae (Johnston and Mawson 1939) Mosgovoi 1951. These records are all new for the New Zealand region except P. decipiens from P. hookeri and C. osculatum from Arctocephalus forsteri. A. simplex and C. osculatum were found associated with gastric ulcers in Arctocephalus forsteri.</p>

scholarly journals Studies on the Life Cycle of Some New Zealand Anisakidae (Nematoda)

2021 ◽  
Author(s):  
◽  
Rosemary Jennifer Hurst
Keyword(s):  
Life Cycle ◽  
New Zealand ◽  
Body Cavity ◽  
The Body ◽  
In Vitro Cultivation ◽  
Free Living ◽  
Larval Stages ◽  
Factors Influencing ◽  
Phocarctos Hookeri

<p>The life cycle of Anisakis simplex in New Zealand waters is described from observations on the morphology, distribution and behaviour of free-living and parasitic stages. Comparison with the life cyles of two other anisakids, Phocanema decipiens Myers 1959 and Thynnascaris adunca Rudolphi 1802 shows differences in distribution, degrees of host specificity, the status of invertebrate hosts, the factors influencing infestation levels of teleost hosts, and the location and pathological effects of infestation. Larval stages occurring in intermediate and paratenic hosts were identified by comparison of larval and adult morphometrics. A. simplex larvae were also positively identified by in vitro cultivation through to adults. Some morphometric variations compared to overseas descriptions are apparent. The ventriculus of A. simplex larvae is shorter relative to body length and the intestinal caecum of P. decipiens is longer relative to ventriculus length. Egg and free-living larval stages were obtained from in vitro cultivation of (A. simplex) and collection of eggs from mature adults from definitive hosts (T. adunca). Eggs of P. decipiens were not obtained. Eggs of A. simplex and T. adunca hatch in 8-11 days at 15 [degrees] C. A. simplex eggs hatch in 6 days at a temperature of 22 [degrees] C and did not hatch in 16 days at 10 [degrees] C. Eggs and free-living stage III larvae of A. simplex and T. adunca are similar in morphology with little differentiation of internal structures. Examination of the stomach contents of pelagic fish infested with anisakids indicated that possible intermediate hosts of A. simplex are the euphausiid Nyctiphanes australis and the decapod Munida gregaria. Possible hosts of T. adunca and M. gregaria are a wide variety of smaller zooplanktonic groups, e.g. decapod larvae and copepods. Larvae of A. simplex were found in one of 8850 N. australis; larvae of T. adunca were found in 69 of 3999 chaetognaths (Sagitta spp.) a medusa and a decapod larva. These larvae are morphologically similar to Stage III larvae from teleosts. No anisakids were found in 3956 Euphausia spp., 1147 M. gregaria and 740 prawns. Twenty five T. adunca larvae and adults were found in 818 freshly eaten M. gregaria in teleost stomachs, indicating that this invertebrate may act as a paratenic and a definitive host. Experimental infection of N. australis and M. gregaria with stage II larvae of A. simplex and T. adunca was unsuccessful. The location of anisakid infestation in three pelagic teleost species, Thyrsites atun, Trachurus novaezelandiae and Trachurus declivis is described. A. simplex larvae are found mainly in the body cavity of all species, at the posterior end of the stomach, with less than one percent occurring in the musculature. Distribution of A. simplex larvae does not change with increasing size of the host or increasing total worm burden. Thyrsites atun have a higher proportion of larvae in the stomach wall (8-13%) compared to Trachurus spp. (< 4%). T. adunca larvae are found infrequently in the body cavity of all three species, on the pyloric caeca and in the stomach wall. Adults and larvae of T. adunca are found more commonly in the alimentary canal, indicating that these teleosts are more important as definitive hosts in the life cycle of this anisakid. P. decipiens larvae are found only in Thyrsites atun and occur mainly in the muscles (98.5%). No quantitative pathogenic effects of anisakid infestation on these teleosts hosts were detected. The main factors influencing the infestation of the three teleost species are age of the host, locality and season. Sex of the host and depth (over the continental shelf, 0-250 m) are not important. A. simplex infestation increased with age in all host species examined, and was higher in Trachurus declivis from the southern-most locality, suggesting the existence of at least two distinct populations of this species. Significant differences in infestation of Thyrsites atun with P. decipiens suggests that this anisakid may be more common in southern localities also. The infestation of Thyrsites atun by larval and adult T. adunca in the alimentary canal is most influenced by season and closely related to diet. Nematode samples were obtained from the marine mammals Arctocephalus forsteri, Kogia breviceps and Phocarctos hookeri. Adult A. simplex were recorded from A. forsteri (a new host record) and Kogia breviceps; preadults from Phocarctos hookeri. Adult P. decipiens were recorded from Phocarctos hookeri; preadults from Arctocephalus forsteri and K. breviceps. Other anisakids found were Anisakis physeteris (Baylis 1923), Contracaecum osculatum Rudolphi 1802 and Pseudoterranova kogiae (Johnston and Mawson 1939) Mosgovoi 1951. These records are all new for the New Zealand region except P. decipiens from P. hookeri and C. osculatum from Arctocephalus forsteri. A. simplex and C. osculatum were found associated with gastric ulcers in Arctocephalus forsteri.</p>

scholarly journals In VivoExpression of Streptococcus pyogenes Immunogenic Proteins during Tibial Foreign Body Infection

2014 ◽  
Vol 82 (9) ◽  
pp. 3891-3899 ◽  
Author(s):  
Jeffrey A. Freiberg ◽  
Kevin S. McIver ◽  
Mark E. Shirtliff
Keyword(s):  
Group A Streptococcus ◽  
Rabbit Model ◽  
Growth Conditions ◽  
Rabbit Serum ◽  
Tissue Samples ◽  
Wide Range ◽  
Group A ◽  
Immunogenic Proteins

ABSTRACTGroup A streptococcus (GAS) is an important human pathogen that causes a number of diseases with a wide range of severities. While all known strains of GAS are still sensitive to penicillin, there have been reports of antibiotic treatment failure in as many as 20% to 40% of cases. Biofilm formation has been implicated as a possible cause for these failures. A biofilm is a microbially derived, sessile community where cells grow attached to a surface or as a bacterial conglomerate and surrounded by a complex extracellular matrix. While the ability of group A streptococcus to form biofilms in the laboratory has been shown, there is a lack of understanding of the role of GAS biofilms during an infection. We hypothesized that during infections, GAS exhibits a biofilm phenotype, complete with unique protein expression. To test this hypothesis, a rabbit model of GAS osteomyelitis was developed. A rabbit was inoculated with GAS using an infected indwelling device. Following the infection, blood and tissue samples were collected. Histological samples of the infected tibia were prepared, and the formation of a biofilmin vivowas visualized using peptide nucleic acid fluorescentin situhybridization (PNA-FISH) and confocal microscopy. In addition, Western blotting with convalescent rabbit serum detected cell wall proteins expressedin vitrounder biofilm and planktonic growth conditions. Immunogenic proteins were then identified using matrix-assisted laser desorption ionization–time of flight tandem mass spectrometry (MALDI-TOF/TOF MS). These identities, along with thein vivoresults, support the hypothesis that GAS forms biofilms during an infection. This unique phenotype should be taken into consideration when designing a vaccine or any other treatment for group A streptococcus infections.

scholarly journals Phyto-oestrogens through the life cycle

2000 ◽  
Vol 59 (3) ◽  
pp. 489-496 ◽  
Author(s):  
Aedin Cassidy ◽  
Marian Faughnan
Keyword(s):  
Life Cycle ◽  
Human Health ◽  
Intestinal Microflora ◽  
Human Subjects ◽  
Epidemiological Data ◽  
Potential Health ◽  
Wide Range

The growing interest in the role of phyto-oestrogens in human health has prompted scientists to evaluate the risk : benefit which would result from consuming high levels of these compounds at different stages of the life cycle. These compounds have been shown to exert a wide range of hormonal and non-hormonal activities in animals and in vitro, and these activities suggest plausible mechanisms for potential health effects in human subjects consuming phyto-oestrogen-rich diets. In addition, experimental and epidemiological data are available supporting the concept that phyto-oestrogen-rich diets exert physiological effects in vivo; however, their relative importance to human health remains to be elucidated. Our understanding of factors involved in their absorption and metabolism, including the role of intestinal microflora, is limited, and these factors together with dose-related effects may well be important in determining clinical efficacy.

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