Sensitivity of Pyricularia oryzae Populations to Fungicides Over a 26-Year Time Frame in Brazil

Plant Disease ◽

10.1094/pdis-08-20-1806-re ◽

2020 ◽

Author(s):

Leilane Silveira D' Ávila ◽

Marta Cristina Corsi Filippi ◽

Adalberto Corrêa Café-Filho

Keyword(s):

Time Frame ◽

Pyricularia Oryzae ◽

Active Ingredients ◽

Melanin Biosynthesis ◽

Gradual Rise ◽

Dmi Fungicides ◽

Term Basis ◽

Collection Period

The long-term dynamics of fungicide resistance of the rice blast fungus Pyricularia oryzae was monitored by examining the reaction of the fungal field isolates, collected over a period of 26 years, to the active ingredients of commercially relevant fungicides. The in vitro sensitivity of all isolates was measured against Quinone outside inhibitors (QoI), Melanin biosynthesis inhibitors (MBI) and Sterol demethylation inhibitor (DMI) fungicides, namely azoxystrobin (QoI), tricyclazole (MBI), tebuconazole (DMI), and trifloxystrobin + tebuconazole (QoI + DMI). Over the 26-year collection period, a gradual rise in the EC50 estimates for mycelial growth sensitivity was observed for all fungicides, but most strikingly for azoxystrobin. A rise in conidial germination and appressorium formation was also noted, most markedly for azoxystrobin. Consistently, the earlier isolates were much more sensitive to the active ingredients than the more contemporary isolates. The sequencing of the amplified cyt b fragment distinguished two haplotypes, H1 and H2. Haplotype H1 (six isolates) contained the G to C transversion at codon 143 (resulting in change G143A), linked to the resistant phenotype QoI-R. Haplotype H2 (40 isolates), gathered the isolates sensitive to QoI. This work documents the gradual rise in the frequency of fungicide resistant isolates in Pyricularia oryzae rice populations on a long-term basis.

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Rapid emergence of clonal interference during malaria parasite cultivation

10.21203/rs.3.rs-51281/v1 ◽

2020 ◽

Author(s):

Catherine Jett ◽

Aliou Dia ◽

ian H. cheeseman

Keyword(s):

Growth Rate ◽

Malaria Parasite ◽

Time Frame ◽

Genomic Variation ◽

Clonal Interference ◽

Long Term Culture ◽

Parasite Plasmodium Falciparum ◽

Cell Genome

Abstract Laboratory cultivation of the malaria parasite Plasmodium falciparum has underpinned nearly all advances in malariology in the past 30 years. When freshly isolated clinical isolates are adapted to in vitro culture mutations rapidly fix increasing the parasite growth rate and stability. While the dynamics of culture adaptation are increasingly well characterized, we know little about the extent of genomic variation that arises and spreads during long term culture. To address this we cloned the 3D7 reference strain and maintained a culture for ~84 asexual cycles (167 days). Growth rate of the culture population increased 1.14-fold over this timeframe. We used single cell genome sequencing of parasites at cycles 21 and 84 to measure the accumulation of diversity in vitro . This parasite population showed strong signals of adaptation across this time frame. By cycle 84 two dominant clades had arisen and were segregating with the dynamics of clonal interference. This highlights the continual process of adaptation in malaria parasites, even in parasites which have been extensively adapted to long term culture.

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In vitro Assessment of Sclerotinia homoeocarpa Resistance to Fungicides and Plant Growth Regulators

Plant Disease ◽

10.1094/pdis-02-10-0098 ◽

2011 ◽

Vol 95 (1) ◽

pp. 51-56 ◽

Cited By ~ 19

Author(s):

Chang-Ho Ok ◽

James T. Popko ◽

Katie Campbell-Nelson ◽

Geunhwa Jung

Keyword(s):

Plant Growth ◽

Plant Growth Regulators ◽

Growth Regulators ◽

Cross Resistance ◽

Sclerotinia Homoeocarpa ◽

Dollar Spot ◽

Active Ingredients ◽

Dmi Fungicides ◽

Fungistatic Effect

Dollar spot (caused by Sclerotinia homoeocarpa) is the most economically important turfgrass disease in North America. This disease is primarily controlled by fungicide applications on golf courses; however, fungicide resistance has been confirmed in three of the four systemic fungicide classes commonly used to control dollar spot. The main objective of this study was to evaluate S. homoeocarpa sensitivity to multiple chemical classes and cross-resistance among active ingredients within the same class; in particular, the association between the fungistatic effect of demethylation inhibitors (DMIs) and plant growth regulators (PGRs). Fifty-eight isolates were selected arbitrarily from four locations in the United States and assayed for in vitro sensitivity to six DMI, two dicarboximide, one carboximide, and one benzimidazole fungicide as well as three type II PGRs. A series of concentrations for each active ingredient was used to determine the mean 50% effective concentration (EC50) values and correlation coefficients were calculated for all active ingredients. The EC50 values of all active ingredients from the DMI class were highly correlated (P < 0.0001) to each other as well as to the one dicarboximide (iprodione) and two PGRs (flurprimidol and paclobutrazol). Isolates resistant to thiophanatemethyl had significantly higher EC50 values than sensitive isolates for all active ingredients assayed except for boscalid. Findings showed that multiple and cross-resistance has developed in S. homoeocarpa and that the two PGRs have a fungistatic effect on this pathogen similar to that of DMI fungicides. The high correlation of in vitro sensitivities among PGRs and DMI fungicides further suggests that PGRs may contribute to the selection of DMI-resistant isolates or facilitate decreased sensitivity to DMI fungicides in the field.

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Long-TermIn VitroDegradation of a High-Strength Brushite Cement in Water, PBS, and Serum Solution

BioMed Research International ◽

10.1155/2015/575079 ◽

2015 ◽

Vol 2015 ◽

pp. 1-17 ◽

Cited By ~ 15

Author(s):

Ingrid Ajaxon ◽

Caroline Öhman ◽

Cecilia Persson

Keyword(s):

Chemical Properties ◽

High Strength ◽

Octacalcium Phosphate ◽

Time Frame ◽

Gravimetric Analysis ◽

Term Evaluation ◽

Physical Changes ◽

Degradation Properties

Bone loss and fractures may call for the use of bone substituting materials, such as calcium phosphate cements (CPCs). CPCs can be degradable, and, to determine their limitations in terms of applications, their mechanical as well as chemical properties need to be evaluated over longer periods of time, under physiological conditions. However, there is lack of data on how thein vitrodegradation affects high-strength brushite CPCs over longer periods of time, that is, longer than it takes for a bone fracture to heal. This study aimed at evaluating the long-termin vitrodegradation properties of a high-strength brushite CPC in three different solutions: water, phosphate buffered saline, and a serum solution. Microcomputed tomography was used to evaluate the degradation nondestructively, complemented with gravimetric analysis. The compressive strength, chemical composition, and microstructure were also evaluated. Major changes from 10 weeks onwards were seen, in terms of formation of a porous outer layer of octacalcium phosphate on the specimens with a concomitant change in phase composition, increased porosity, decrease in object volume, and mechanical properties. This study illustrates the importance of long-term evaluation of similar cement compositions to be able to predict the material’s physical changes over a relevant time frame.

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Coaxial Alginate Hydrogels: From Self-Assembled 3D Cellular Constructs to Long-Term Storage

International Journal of Molecular Sciences ◽

10.3390/ijms22063096 ◽

2021 ◽

Vol 22 (6) ◽

pp. 3096

Author(s):

Oleksandr Gryshkov ◽

Vitalii Mutsenko ◽

Dmytro Tarusin ◽

Diaa Khayyat ◽

Ortwin Naujok ◽

...

Keyword(s):

3D Culture ◽

Cellular Structures ◽

Core Shell ◽

Low Viscosity ◽

Long Term Storage ◽

Cryopreserved Cell ◽

Term Basis ◽

Self Assembled

Alginate as a versatile naturally occurring biomaterial has found widespread use in the biomedical field due to its unique features such as biocompatibility and biodegradability. The ability of its semipermeable hydrogels to provide a favourable microenvironment for clinically relevant cells made alginate encapsulation a leading technology for immunoisolation, 3D culture, cryopreservation as well as cell and drug delivery. The aim of this work is the evaluation of structural properties and swelling behaviour of the core-shell capsules for the encapsulation of multipotent stromal cells (MSCs), their 3D culture and cryopreservation using slow freezing. The cells were encapsulated in core-shell capsules using coaxial electrospraying, cultured for 35 days and cryopreserved. Cell viability, metabolic activity and cell–cell interactions were analysed. Cryopreservation of MSCs-laden core-shell capsules was performed according to parameters pre-selected on cell-free capsules. The results suggest that core-shell capsules produced from the low viscosity high-G alginate are superior to high-M ones in terms of stability during in vitro culture, as well as to solid beads in terms of promoting formation of viable self-assembled cellular structures and maintenance of MSCs functionality on a long-term basis. The application of 0.3 M sucrose demonstrated a beneficial effect on the integrity of capsules and viability of formed 3D cell assemblies, as compared to 10% dimethyl sulfoxide (DMSO) alone. The proposed workflow from the preparation of core-shell capsules with self-assembled cellular structures to the cryopreservation appears to be a promising strategy for their off-the-shelf availability.

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Heterologous production of 1-tuberculosinyladenosine in Mycobacterium kansasii models pathoevolution towards the transcellular lifestyle of Mycobacterium tuberculosis

10.1101/2020.04.25.060590 ◽

2020 ◽

Author(s):

Marwan Ghanem ◽

Jean-Yves Dubé ◽

Joyce Wang ◽

Fiona McIntosh ◽

Daniel Houle ◽

...

Keyword(s):

Virulence Factors ◽

Ex Vivo ◽

Time Frame ◽

Specific Gene ◽

Bacterial Survival ◽

Mycobacterium Kansasii ◽

Lipid Species ◽

Intrinsic Mechanism

ABSTRACTMycobacterium kansasii is an environmental non-tuberculous mycobacterium that causes opportunistic tuberculosis-like disease. It is one of the most closely related species to the M. tuberculosis complex. Using M. kansasii as a proxy for the M. kansasii-M. tuberculosis-common ancestor, we asked whether introducing the M. tuberculosis-specific gene pair Rv3377c-Rv3378c into M. kansasii affects the course of experimental infection. Expression of these genes resulted in the production of an adenosine-linked lipid species, known as 1-tuberculosinyladenosine (1-TbAd), but did not alter growth in vitro under standard conditions. Production of 1-TbAd enhanced growth of M. kansasii under acidic conditions through a bacterial cell-intrinsic mechanism independent of controlling pH in the bulk extracellular and intracellular spaces. Production of 1-TbAd led to greater burden of M. kansasii in the lung of C57Bl/6 mice during the first 24 hours after infection and ex vivo infections of alveolar macrophages recapitulated this phenotype within the same time frame. However, in long-term infections, production of 1-TbAd resulted in impaired bacterial survival in both C57Bl/6 mice and Ccr2-/- mice. We have demonstrated that M. kansasii is a valid surrogate of M. tuberculosis to study virulence factors acquired by the latter organism, yet shown the challenge inherent to studying the complex evolution of mycobacterial pathogenicity with isolated gene complementation.IMPORTANCEThis work sheds light on the role of the lipid 1-tuberculosinyladenosine in the evolution of an environmental ancestor to M. tuberculosis. On a larger scale, it reinforces the importance of horizontal gene transfer in bacterial evolution and examines novel models and methods to provide a better understanding of the subtle effects of individual M. tuberculosis-specific virulence factors in infection settings that are relevant to the pathogen.

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Rapid emergence of clonal interference during malaria parasite cultivation

10.1101/2020.03.04.977165 ◽

2020 ◽

Author(s):

Catherine Jett ◽

Aliou Dia ◽

Ian H. Cheeseman

Keyword(s):

Growth Rate ◽

Malaria Parasite ◽

Time Frame ◽

Genomic Variation ◽

Clonal Interference ◽

Long Term Culture ◽

Cell Genome ◽

Rapid Emergence

AbstractLaboratory cultivation of the malaria parasite Plasmodium falciparum has underpinned nearly all advances in malariology in the past 30 years. When freshly isolated clinical isolates are adapted to in vitro culture mutations rapidly fix increasing the parasite growth rate and stability. While the dynamics of culture adaptation are increasingly well characterized, we know little about the extent of genomic variation that arises and spreads during long term culture. To address this we cloned the 3D7 reference strain and maintained a culture for ~84 asexual cycles (167 days). Growth rate of the culture population increased 1.14-fold over this timeframe. We used single cell genome sequencing of parasites at cycles 21 and 84 to measure the accumulation of diversity in vitro. This parasite population showed strong signals of adaptation across this time frame. By cycle 84 two dominant clades had arisen and were segregating with the dynamics of clonal interference. This highlights the continual process of adaptation in malaria parasites, even in parasites which have been extensively adapted to long term culture.

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Long-term in vitro degradation and in vivo evaluation of resorbable bioceramics

Journal of Materials Science Materials in Medicine ◽

10.1007/s10856-020-06488-1 ◽

2021 ◽

Vol 32 (1) ◽

Author(s):

Ying-Cen Chen ◽

Pei-Yi Hsu ◽

Wei-Hsing Tuan ◽

Chih-Yi Chen ◽

Chia-Jung Wu ◽

...

Keyword(s):

Strong Dependence ◽

Time Frame ◽

Relative Volume ◽

In Vivo Evaluation ◽

In Vitro Degradation ◽

Degradation Analysis ◽

Reasonable Time Frame

AbstractAn essential criterion for the selection of resorbable bioceramics is their ability to degrade inside human body within a reasonable time frame. Furthermore, if the bioceramic can release beneficial ions, such as strontium, as it degrades, recovery time might be shortened. The present study demonstrates that strontium-containing calcium sulfate (Sr,Ca)SO4 can fulfill these criteria. A long-term in vitro degradation analysis for 12 weeks using sintered (Sr,Ca)SO4 discs in phosphate buffered solution (PBS) was conducted. The sintered (Sr,Ca)SO4 disc was then implanted into defects in the distal femur of rats. The degradation rate of (Sr,Ca)SO4 discs showed a strong dependence on the Sr content. Similar results were observed between the long-term in vitro degradation analysis and the in vivo evaluation. The sintered (3.8%Sr,Ca)SO4 disc lost more than 80% of its initial weight after soaking in PBS with shaking at 37 °C for 12 weeks. After 12 weeks in vivo, the remaining volume of the (3.8%Sr,Ca)SO4 disc within the bone defect was ~25%. Over the same time period, new bone was formed at a relative volume of 40%. This study demonstrates the potential of (Sr,Ca)SO4 bioceramic, and the benefits of using a long-term degradation test during the evaluation of resorbable bioceramics.

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Ultrastructural investigations of MDL 19,660-induced effects on the canine platelet and megakaryocyte

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100159412 ◽

1990 ◽

Vol 48 (3) ◽

pp. 374-375

Author(s):

D.E. Loudy ◽

J. Sprinkle-Cavallo ◽

J.T. Yarrington ◽

F.Y. Thompson ◽

J.P. Gibson

Keyword(s):

Antidepressant Drug ◽

Beagle Dogs ◽

Long Term Effects ◽

Short Term ◽

Platelet Counts ◽

Toxicological Studies ◽

Induced Aggregation ◽

Internal Architecture

Previous short term toxicological studies of one to two weeks duration have demonstrated that MDL 19,660 (5-(4-chlorophenyl)-2,4-dihydro-2,4-dimethyl-3Hl, 2,4-triazole-3-thione), an antidepressant drug, causes a dose-related thrombocytopenia in dogs. Platelet counts started to decline after two days of dosing with 30 mg/kg/day and continued to decrease to their lowest levels by 5-7 days. The loss in platelets was primarily of the small discoid subpopulation. In vitro studies have also indicated that MDL 19,660: does not spontaneously aggregate canine platelets and has moderate antiaggregating properties by inhibiting ADP-induced aggregation. The objectives of the present investigation of MDL 19,660 were to evaluate ultrastructurally long term effects on platelet internal architecture and changes in subpopulations of platelets and megakaryocytes.Nine male and nine female beagle dogs were divided equally into three groups and were administered orally 0, 15, or 30 mg/kg/day of MDL 19,660 for three months. Compared to a control platelet range of 353,000- 452,000/μl, a doserelated thrombocytopenia reached a maximum severity of an average of 135,000/μl for the 15 mg/kg/day dogs after two weeks and 81,000/μl for the 30 mg/kg/day dogs after one week.

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