Journal Articles

Permanent URI for this collectionhttps://mro.massey.ac.nz/handle/10179/7915

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Start date: 2020Subject: search.filters.subject.resistance

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    Molecular Investigation of Rlm3 From Rapeseed as a Potential Broad-Spectrum Resistance Gene Against Fungal Pathogens Producing Structurally Conserved Effectors
    (John Wiley and Sons Ltd on behalf of British Society for Plant Pathology, 2025-09-21) Talbi N; Pakzad S; Blaise F; Ollivier B; Rouxel T; Balesdent M-H; Blondeau K; Lazar N; van Tilbeurgh H; Mesarich CH; Fudal I
    Recognition of a pathogen avirulence (AVR) effector protein by its cognate plant resistance (R) protein triggers immune responses that are typically sufficient to provide effective disease control. While AVR effectors have long been considered species- or genotype-specific, several studies have recently shown that these proteins belong to a limited set of structural families. This finding paves the way for the identification or engineering of broad-spectrum R proteins capable of recognising several members of the same structural family. In the Leptosphaeria maculans–rapeseed (Brassica napus) pathosystem, 13 AVR genes have been cloned, of which four encode effectors belonging to the LARS (Leptosphaeria AviRulence and Suppressing) structural family. Homologues of the L. maculans AvrLm3 AVR protein, a LARS family member, have been identified in other fungal species, including an AVR protein from Fulvia fulva, Ecp11-1. We have previously shown that Ecp11-1 is recognised by rapeseed varieties carrying the Rlm3 R gene, and that this recognition is masked in the presence of another LARS AVR gene, AvrLm4-7. In this study, we expanded our characterisation of the Rlm3 resistance spectrum to effectors from Fusarium oxysporum and Zymoseptoria ardabiliae. Like Ecp11-1, we showed that an effector from F. oxysporum f. sp. narcissi is recognised by Rlm3, and that this recognition is masked in the presence of AvrLm4-7. We also investigated which protein regions and amino acids are necessary for AvrLm3 and Ecp11-1 recognition by Rlm3. This analysis is a first step towards the identification of broad-spectrum R proteins that confer protection against multiple phytopathogens.
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    Reduced anthelmintic use on 13 New Zealand sheep farms: farmer motivations and practical implementation
    (Taylor and Francis Group on behalf of the New Zealand Veterinary Association, 2024-09-19) Ridler AL; Hytten K; Gray DI; Reid JI
    AIMS: To describe the personal drivers, sources of information and gastro-intestinal parasite control methods used by a group of New Zealand sheep farmers identified as low users of anthelmintic (AHC), and their perception of the efficacy and impacts of this approach. METHODS: A convenience sample of 13 sheep farmers farming with a policy of reduced AHC use (no pre-determined routine treatments of ewes >19 months old and/or lambs not routinely treated at pre-determined intervals from weaning through to late autumn) were identified. Semi-structured interviews were conducted regarding their farming philosophy, motivations for reducing AHC use, perceptions of the impacts of farming with reduced AHC use, and parasite control practices. Semi-quantitative data were analysed using descriptive statistics for demographic data and categorising participants' use of AHC and non-chemical control methods. Qualitative data regarding participants' motivations, approaches and rationale were analysed by systematic analysis of the transcripts and distillation of key concepts. RESULTS: Participants had been operating with reduced AHC use for 3 to  ≥20 years. Key motivators for reducing AHC use were a diagnosis of anthelmintic resistance (AR) or concerns about AR developing. Parasite management information came from a wide range of sources. All respondents expressed overall positive views regarding the impacts of reduced AHC use but detailed information was not available.All identified that regular monitoring, based primarily on subjective animal and non-animal factors was important for their parasite control strategy. Most used faecal egg counts (FEC), often in an ad hoc manner. Five never treated adult ewes, two routinely treated ewes prior to lambing with short-acting AHC and the remainder occasionally treated a small number in low body condition. Four routinely treated some or all lambs at 28-30-day intervals from weaning to late autumn while the remainder based their treatment decisions for lambs on monitored information. All placed heavy emphasis on feeding sheep well, ensuring high post-grazing residuals, and cross-grazing. CONCLUSIONS: AR was a key motivator for participants to reduce AHC use, and a range of information sources and decision-making processes were used. Key parasite management practices were monitoring, primarily using subjective assessments, emphasis on feeding stock well and cross-grazing. CLINICAL RELEVANCE: The rising prevalence of AR will likely result in increasing the motivation for sheep farmers to reduce their AHC use. Veterinarians will play a key role in providing advice and assistance to facilitate changes in parasite management.
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    Editorial: Antibiotic potentiators against drug-resistant pathogens: Discovery, development and clinical applications.
    (Frontiers Media S.A., 2023-03-07) Das B; Mahajan D; Rakonjac J; Aminov R
    Antimicrobial resistance (AMR) is a natural evolutionary consequence induced by massive antibiotic usage. The significantly higher rate of AMR and its spread is largely attributed to the illicit use and management of antibiotics, their production, and residual disposal in the environment (Das et al., 2017). AMR-associated and -contributed deaths are expected to exceed 4.5 million in 2023 due to the global spread of AMR in clinically important pathogens (Antimicrobial Resistance Collaborators, 2022). In addition, the issue of AMR is also plaguing the management of other clinical conditions such as organ transplantation, microbiome transplantation, and inflammation management in chronic metabolic diseases leading to poor success rates. To tackle the AMR crisis and identify novel antibiotics or alternatives to antibiotics, several global initiatives are at different stages of completion (Narendrakumar et al., 2022). The current special issue covers updated research initiatives expanding the toolset against AMR pathogens by including (i) repurposed, already approved, drugs normally used for the treatment of non-infectious diseases; (ii) antibiotic potentiators that are not antibacterials, but rather block the resistance functions or increase membrane permeability, thus enhance antibiotics' activity; (iii) synergistic combinations of antibiotics; (iv) alternative therapies to minimize antibiotic uses.
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    Apparent resistance to brodifacoum in Rattus rattus in a New Zealand site with no history of anticoagulant-based rodent control
    (CSIRO Publishing, 2022-07-07) Sran SPK; Gartrell BG; Fisher P; Armstrong DP; Belmain S
    Context: Anticoagulants have been used in New Zealand for decades, but few data are available on the sustainability of these toxins for rodent control. It is important to regularly monitor for resistance in long-term brodifacoum-use areas and establish a database for future references. Aims: This study aimed to estimate the effective dose (ED50) of brodifacoum for ship rats from an area of New Zealand with no history of brodifacoum use, in order to establish a blood-clotting response test for assessing resistance in rodent populations from other areas. Methods: A ranging study was conducted whereby successive groups of ship rats were administered brodifacoum doses that were increased or decreased progressively, until an International Normalised Ratio (INR) of 3.6 was reached. Linear regression was used to model the relationship between dose and INR, and ED50 dose was estimated using the resulting model. Results: None of the rats appeared susceptible to brodifacoum at previously reported LD50 exposures for this species. The ED50 of brodifacoum was estimated to be 2.88 mg/kg for males and 3.81 mg/kg for females. These values are 6-8 times greater than the previously published lethal dose values for ship rats in New Zealand. Conclusions: Blood-clotting inhibition was detected in the rats only following high doses of brodifacoum, which may indicate resistance within the sampled population. Implications: Relatively low susceptibility, or resistance, to brodifacoum in New Zealand ship rats may be mediated by spatial connections between areas with different histories and patterns of anticoagulant rodenticide use.
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    Muted resistance: The deployment of youth voice in news coverage of young women’s sexuality in Aotearoa New Zealand
    (SAGE Journals, 1/02/2020) Morison T; Herbert S
    Youth sexuality is typically constructed as a social problem, and associated with a range of negative consequences for larger society and for young people themselves—especially young women. The media play a role in perpetuating this dominant construction, but may also offer a space for resistance. In this article, mainstream news media reportage on youth sexual and reproductive issues in Aotearoa are discursively analysed to identify instances of resistance to oppressive discourses. Taking a feminist poststructuralist perspective, the aim is to connect news reporting, as a representational practice, with broader relations of power. The focus of the analysis, therefore, is on whether and how young people are allowed a voice in news reportage, and to what effect their voices are deployed. The analysis demonstrates not only that youth voice is relatively muted in comparison to experts, but also that it is frequently used to reinforce the dominant constructions of youth sexuality (as problematic and risky). Yet, instances of resistance are also evident. These are assessed in relation to their impact on gender power relations and possibilities for amplifying resistance are discussed.