6 results on '"Katarzyna Ignasiak"'
Search Results
2. Oxytetracycline reduces the diversity of tetracycline-resistance genes in the Galleria mellonella gut microbiome
- Author
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Katarzyna Ignasiak and Anthony Maxwell
- Subjects
Antibiotic resistance ,Tetracycline-resistance elements ,Oxytetracycline ,Galleria mellonella ,Lepidoptera ,Greater wax moth ,Microbiology ,QR1-502 - Abstract
Abstract Background Clinically-relevant multidrug resistance is sometimes present in bacteria not exposed to human-made antibiotics, in environments without extreme selective pressures, such as the insect gut. The use of antibiotics on naïve microbiomes often leads to decreased microbe diversity and increased antibiotic resistance. Results Here we investigate the impact of antibiotics on the insect gut microbiome by identifying tetracycline-resistance genes in the gut bacteria of greater wax moth (Galleria mellonella) larvae, feeding on artificial food containing oxytetracycline. We determined that G. mellonella can be raised on artificial food for over five generations and that the insects tolerate low doses of antibiotics in their diets, but doses of oxytetracycline higher than sub-inhibitory lead to early larval mortality. In our experiments, greater wax moth larvae had a sparse microbiome, which is consistent with previous findings. Additionally, we determined that the microbiome of G. mellonella larvae not exposed to antibiotics carries a number of tetracycline-resistance genes and some of that diversity is lost upon exposure to strong selective pressure. Conclusions We show that G. mellonella larvae can be raised on artificial food, including antibiotics, for several generations and that the microbiome can be sampled. We show that, in the absence of antibiotics, the insect gut microbiome can maintain a diverse pool of tetracycline-resistance genes. Selective pressure, from exposure to the antibiotic oxytetracycline, leads to microbiome changes and alteration in the tetracycline-resistance gene pool.
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- 2018
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3. Antibiotic-resistant bacteria in the guts of insects feeding on plants: prospects for discovering plant-derived antibiotics
- Author
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Katarzyna Ignasiak and Anthony Maxwell
- Subjects
Microbiome ,Antibiotic susceptibility ,Phytochemicals ,Metabolites ,Microbiology ,QR1-502 - Abstract
Abstract Background Although plants produce many secondary metabolites, currently none of these are commercial antibiotics. Insects feeding on specific plants can harbour bacterial strains resistant to known antibiotics suggesting that compounds in the plant have stimulated resistance development. We sought to determine whether the occurrence of antibiotic-resistant bacteria in insect guts was a widespread phenomenon, and whether this could be used as a part of a strategy to identify antibacterial compounds from plants. Results Six insect/plant pairs were selected and the insect gut bacteria were identified and assessed for antibiotic susceptibilities compared with type strains from culture collections. We found that the gut strains could be more or less susceptible to antibiotics than the type strains, or show no differences. Evidence of antibacterial activity was found in the plant extracts from five of the six plants, and, in one case Catharanthus roseus (Madagascar Periwinkle), compounds with antibacterial activity were identified. Conclusion Bacterial strains isolated from insect guts show a range of susceptibilities to antibiotics suggesting a complex interplay between species in the insect gut microbiome. Extracts from selected plants can show antibacterial activity but it is not easy to isolate and identify the active components. We found that vindoline, present in Madagascar Periwinkle extracts, possessed moderate antibacterial activity. We suggest that plant-derived antibiotics are a realistic possibility given the advances in genomic and metabolomic methodologies.
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- 2017
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4. Galleria mellonella (greater wax moth) larvae as a model for antibiotic susceptibility testing and acute toxicity trials
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Katarzyna Ignasiak and Anthony Maxwell
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Galleria mellonella ,Infectivity testing ,Toxicity trials ,Antibiotics ,Medicine ,Biology (General) ,QH301-705.5 ,Science (General) ,Q1-390 - Abstract
Abstract Background Infectivity trials and toxicity testing in rodents are important prerequisites to the use of compounds in man. However, trials in rats and mice are expensive and there are ethical considerations. Galleria mellonella (greater wax moth) larvae are a potential alternative. We have assessed the use of these insects in infectivity trials and toxicity testing. Findings Using four bacterial species (two Gram-negative and two Gram-positive) we have assessed the efficacy of four antibiotics against infections in Galleria and compared the antibiotic susceptibility with that in humans. In general, we find a good correlation. Similarly, we have assessed 11 compounds (initially tested blind) for their toxicity in Galleria and compared this with toxicity trials in mice and rats. Again we found a good correlation between toxicity in Galleria and that in rodents. Conclusion We have found, in our hands, that G. mellonella larvae can be used in infectivity trials and toxicity testing, and that these assays represent an inexpensive and readily executable alternative to testing in rodents.
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- 2017
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5. Amylin and beta amyloid proteins interact to form amorphous heterocomplexes with enhanced toxicity in neuronal cells
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Tanya Solomon, Scott Gaskin, Joanne Rowles, Bikash R. Sahoo, Ayyalusamy Ramamoorthy, Prashant Bharadwaj, Giuseppe Verdile, Mark J. Howard, Philip Newsholme, Ralph N. Martins, Katarzyna Ignasiak, and Charles S. Bond
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0301 basic medicine ,Programmed cell death ,endocrine system ,Amyloid ,Amylin ,lcsh:Medicine ,Protein aggregation ,Protein Aggregation, Pathological ,Article ,Protein Aggregates ,03 medical and health sciences ,0302 clinical medicine ,Microscopy, Electron, Transmission ,Alzheimer Disease ,Cell Line, Tumor ,medicine ,Animals ,Humans ,Neurodegeneration ,lcsh:Science ,Nuclear Magnetic Resonance, Biomolecular ,Pancreas ,Neurons ,geography ,Amyloid beta-Peptides ,Multidisciplinary ,geography.geographical_feature_category ,Chemistry ,lcsh:R ,Neurotoxicity ,Brain ,Alzheimer's disease ,Islet ,medicine.disease ,Peptide Fragments ,Islet Amyloid Polypeptide ,Rats ,030104 developmental biology ,Diabetes Mellitus, Type 2 ,Cell culture ,Biophysics ,lcsh:Q ,Protein Multimerization ,030217 neurology & neurosurgery - Abstract
Human pancreatic islet amyloid polypeptide (hIAPP) and beta amyloid (Aβ) can accumulate in Type 2 diabetes (T2D) and Alzheimer’s disease (AD) brains and evidence suggests that interaction between the two amyloidogenic proteins can lead to the formation of heterocomplex aggregates. However, the structure and consequences of the formation of these complexes remains to be determined. The main objective of this study was to characterise the different types and morphology of Aβ-hIAPP heterocomplexes and determine if formation of such complexes exacerbate neurotoxicity. We demonstrate that hIAPP promotes Aβ oligomerization and formation of small oligomer and large aggregate heterocomplexes. Co-oligomerized Aβ42-hIAPP mixtures displayed distinct amorphous structures and a 3-fold increase in neuronal cell death as compared to Aβ and hIAPP alone. However, in contrast to hIAPP, non-amyloidogenic rat amylin (rIAPP) reduced oligomer Aβ-mediated neuronal cell death. rIAPP exhibited reductions in Aβ induced neuronal cell death that was independent of its ability to interact with Aβ and form heterocomplexes; suggesting mediation by other pathways. Our findings reveal distinct effects of IAPP peptides in modulating Aβ aggregation and toxicity and provide new insight into the potential pathogenic effects of Aβ-IAPP hetero-oligomerization and development of IAPP based therapies for AD and T2D.
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- 2020
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6. The macrocyclizing protease butelase 1 remains autocatalytic and reveals the structural basis for ligase activity
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Joel Haywood, Alysha G. Elliott, Jason W. Schmidberger, Charles S. Bond, Amy M. James, Joshua S. Mylne, Ricarda Fenske, Katarzyna Ignasiak, Samuel G Nonis, Julie Leroux, and Mark F. Fisher
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0106 biological sciences ,0301 basic medicine ,Arabidopsis thaliana ,enzymology ,medicine.medical_treatment ,Mutant ,Arabidopsis ,Plant Science ,Clitoria ternatea ,Cleavage (embryo) ,Crystallography, X-Ray ,01 natural sciences ,Catalysis ,Ligases ,03 medical and health sciences ,Catalytic Domain ,Genetics ,medicine ,structural biology ,Ligase activity ,Plant Proteins ,chemistry.chemical_classification ,DNA ligase ,Protease ,macrocyclization ,biology ,Seed Storage Proteins ,Active site ,protease ,Cell Biology ,Biological Evolution ,Recombinant Proteins ,Models, Structural ,Cysteine Endopeptidases ,030104 developmental biology ,Structural biology ,chemistry ,Biochemistry ,Plant protein ,Cyclization ,Mutation ,biology.protein ,biosynthesis ,Clitoria ,010606 plant biology & botany - Abstract
Plant asparaginyl endopeptidases (AEPs) are expressed as inactive zymogens that perform seed storage protein maturation upon cleavage dependent auto-activation in the low pH environment of storage vacuoles. AEPs have attracted attention for their macrocyclization reactions and have been classified as cleavage or ligation specialists. However, we have recently shown that the ability of AEPs to produce either cyclic or acyclic products can be altered by mutations to the active site region, and that several AEPs are capable of macrocyclization given favorable pH conditions. One AEP extracted from Clitoria ternatea seeds (butelase 1) is classified as a ligase rather than a protease, presenting an opportunity to test for loss of cleavage activity. Here, making recombinant butelase 1 and rescuing an Arabidopsis thaliana mutant lacking AEP, we show butelase 1 retains cleavage functions in vitro and in vivo. The in vivo rescue was incomplete, consistent with some trade-off for butelase 1 specialization toward macrocyclization. Its crystal structure showed an active site with only subtle differences from cleaving AEPs, suggesting the many differences in its peptide binding region are the source of its efficient macrocyclization. All considered, it seems either butelase 1 has not fully specialized or a requirement for auto-catalytic cleavage is an evolutionary constraint upon macrocyclizing AEPs.
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- 2018
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