Glandular trichomes: Enzymic browning assays for improved selection of resistance to the green peach aphid

1983 ◽  
Vol 60 (11) ◽  
pp. 861-868 ◽  
Author(s):  
James D. Ryan ◽  
Peter Gregory ◽  
Ward M. Tingey
Keyword(s):  
Green Peach Aphid ◽  
Glandular Trichomes ◽  
Enzymic Browning ◽  
Selection Of ◽  
Selection Of Resistance

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 Insecticide resistance status of Anopheles arabiensis in irrigated and non-irrigated areas in western Kenya

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Pauline Winnie Orondo ◽  
Steven G. Nyanjom ◽  
Harrysone Atieli ◽  
John Githure ◽  
Benyl M. Ondeto ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Vector Control ◽  
Anopheles Arabiensis ◽  
Crop Protection ◽  
Indoor Residual Spraying ◽  
Malaria Vectors ◽  
Western Kenya ◽  
Animal Protection ◽  
Selection Of ◽  
Selection Of Resistance

Abstract Background Malaria control in Kenya is based on case management and vector control using long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS). However, the development of insecticide resistance compromises the effectiveness of insecticide-based vector control programs. The use of pesticides for agricultural purposes has been implicated as one of the sources driving the selection of resistance. The current study was undertaken to assess the status and mechanism of insecticide resistance in malaria vectors in irrigated and non-irrigated areas with varying agrochemical use in western Kenya. Methods The study was carried out in 2018–2019 in Homa Bay County, western Kenya. The bioassay was performed on adults reared from larvae collected from irrigated and non-irrigated fields in order to assess the susceptibility of malaria vectors to different classes of insecticides following the standard WHO guidelines. Characterization of knockdown resistance (kdr) and acetylcholinesterase-inhibiting enzyme/angiotensin-converting enzyme (Ace-1) mutations within Anopheles gambiae s.l. species was performed using the polymerase chain reaction (PCR) method. To determine the agricultural and public health insecticide usage pattern, a questionnaire was administered to farmers, households, and veterinary officers in the study area. Results Anopheles arabiensis was the predominant species in the irrigated (100%, n = 154) area and the dominant species in the non-irrigated areas (97.5%, n = 162), the rest being An. gambiae sensu stricto. In 2018, Anopheles arabiensis in the irrigated region were susceptible to all insecticides tested, while in the non-irrigated region reduced mortality was observed (84%) against deltamethrin. In 2019, phenotypic mortality was decreased (97.8–84% to 83.3–78.2%). In contrast, high mortality from malathion (100%), DDT (98.98%), and piperonyl butoxide (PBO)-deltamethrin (100%) was observed. Molecular analysis of the vectors from the irrigated and non-irrigated areas revealed low levels of leucine-serine/phenylalanine substitution at position 1014 (L1014S/L1014F), with mutation frequencies of 1–16%, and low-frequency mutation in the Ace-1R gene (0.7%). In addition to very high coverage of LLINs impregnated with pyrethroids and IRS with organophosphate insecticides, pyrethroids were the predominant chemical class of pesticides used for crop and animal protection. Conclusion Anopheles arabiensis from irrigated areas showed increased phenotypic resistance, and the intensive use of pesticides for crop protection in this region may have contributed to the selection of resistance genes observed. The susceptibility of these malaria vectors to organophosphates and PBO synergists in pyrethroids offers a promising future for IRS and insecticide-treated net-based vector control interventions. These findings emphasize the need for integrated vector control strategies, with particular attention to agricultural practices to mitigate mosquito resistance to insecticides. Graphic abstract

scholarly journals Macroscopy and Microscopy Study of Scopraia dulcis L.

2018 ◽  
Vol 23 (1) ◽  
pp. 56
Author(s):  
Djoko Santosa ◽  
Subagus Wahyuono ◽  
Sugeng Riyanto ◽  
SM Widyastuti
Keyword(s):  
Glandular Trichomes ◽  
Principal Component ◽  
Morphological Diversity ◽  
Microscopy Study ◽  
Sampling Location ◽  
Scoparia Dulcis ◽  
Region Selection ◽  
Microscopy Analysis ◽  
Palisade Cells ◽  
Selection Of

A morphological diversity analysis of Scoparia dulcis by macroscopy and microscopy has been conducted. The aim of this research is to determine the morphological and anatomical character of S. dulcis which grow in Opak watershed, Special Region of Yogyakarta. Samples were taken from Sleman (Cangkringan, Ngemplak Kalasan, and Prambanan) and Bantul (Imogiri and Pundong) region. Selection of sampling location is based on altitude difference. The samples are the third leaf order from the tip of the stem. They were measured in length and width. Microscopy analysis was performed by observing the number of glandular trichomes, palisade cells in the epidermis and stomata in the upper and lower epidermis. The data obtained were analyzed using principal component analysis (PCA). The results show that based on morphological and anatomical assessment, there were found 3 clusters of S. dulcis, i.e. Cangkringan-Ngemplak-Prambanan, Kalasan, and Imogiri-Pundong cluster.

scholarly journals In vitro antimicrobial combination testing of and evolution of resistance to the first-in-class spiropyrimidinetrione zoliflodacin combined with six therapeutically relevant antimicrobials for Neisseria gonorrhoeae

2019 ◽  
Vol 74 (12) ◽  
pp. 3521-3529 ◽  
Author(s):  
Sunniva Foerster ◽  
George Drusano ◽  
Daniel Golparian ◽  
Michael Neely ◽  
Laura J V Piddock ◽  
...  
Keyword(s):  
Neisseria Gonorrhoeae ◽  
Single Agent ◽  
Curve Analysis ◽  
Phase Iii ◽  
Transmitted Infection ◽  
Kill Curve ◽  
Time Kill ◽  
Selection Of ◽  
Selection Of Resistance

Abstract Objectives Resistance in Neisseria gonorrhoeae to all gonorrhoea therapeutic antimicrobials has emerged. Novel therapeutic antimicrobials are imperative and the first-in-class spiropyrimidinetrione zoliflodacin appears promising. Zoliflodacin could be introduced in dual antimicrobial therapies to prevent the emergence and/or spread of resistance. We investigated the in vitro activity of and selection of resistance to zoliflodacin alone and in combination with six gonorrhoea therapeutic antimicrobials against N. gonorrhoeae. Methods The international gonococcal reference strains WHO F (WT) and WHO O, WHO V and WHO X (strains with different AMR profiles) were examined. Zoliflodacin was evaluated alone or combined with ceftriaxone, cefixime, spectinomycin, gentamicin, tetracycline, cethromycin or sitafloxacin in chequerboard assays, time–kill curve analysis and selection-of-resistance studies. Results Zoliflodacin alone or in combination with all six antimicrobials showed rapid growth inhibition against all examined strains. The time–kill curve analysis indicated that tetracycline or cethromycin combined with zoliflodacin can significantly decrease the zoliflodacin kill rate in vitro. The frequency of selected zoliflodacin-resistance mutations was low when evaluated as a single agent and further reduced for all antimicrobial combinations. All resistant mutants contained the GyrB mutations D429N, K450T or K450N, resulting in zoliflodacin MICs of 0.5–4 mg/L. Conclusions Zoliflodacin, alone or in combination with sexually transmitted infection therapeutic antimicrobials, rapidly kills gonococci with infrequent resistance emergence. Zoliflodacin remains promising for gonorrhoea oral monotherapy and as part of dual antimicrobial therapy with low resistance emergence potential. A Phase III trial evaluating efficacy and safety of zoliflodacin for uncomplicated gonorrhoea treatment is planned in 2019.

In vitro selection of resistance to sofosbuvir in HCV replicons of genotype 1 to 6

2017 ◽  
Vol 22 (7) ◽  
pp. 587-597 ◽  
Author(s):  
Simin Xu ◽  
Brian Doehle ◽  
Sonal Rajyaguru ◽  
Bin Han ◽  
Ona Barauskas ◽  
...  
Keyword(s):  
In Vitro Selection ◽  
Genotype 1 ◽  
Selection Of ◽  
Selection Of Resistance
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