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Safeguarding global plant health: the rise of sentinels
Get PDFPublication history: Accepted - 28 August 2018; Published online - 04 September 2018; Published - 15 January 2019The number of alien plant pests and pathogens is rapidly increasing in many countries as a result of increasing trade, particularly the trade in living plants. Sentinel plantings in exporting countries to detect arthropod pests and agents of diseases prior to introduction provide information about the likelihood of introduction and the potential impact on plants native to the importing country. Such plantings can consist of species that are native to exporting or importing countries (“in-patria” and “ex-patria” plantings). In-patria plantings consist of young woody plants of species that are commonly exported and can be used to identify pests that may be introduced to new countries via the trade in live plants. Ex-patria plantings consist of exotic young or mature woody plants and surveys may provide information about potential impacts of pests if these were to become established in a new country. We discuss the methods and benefits of this powerful tool and list examples of studies that highlight the large number of unknown organisms and pest–host relationships that can be detected. The usefulness of sentinel plantings is illustrated using examples of arthropod pests and fungal pathogens of European and Asian tree species that were identified in sentinel studies in China and the Asian Russia
Emergence of a non-sporulating secondary phenotype in Clostridium (Clostridioides) difficile ribotype 078 isolated from humans and animals
Get PDFPublication history: Accepted - 27 August 2019, Published - 23 September 2019Clostridium (Clostridioides) difficile is a Gram positive, spore forming anaerobic bacterium that is a leading cause of antibiotic associated diarrhoea in the developed world. C. difficile is a genetically diverse species that can be divided into 8 phylogenetically distinct clades with clade 5 found to be genetically distant from all others. Isolates with the PCR ribotype 078 belong to clade 5, and are often associated with C. difficile infection in both humans and animals. Colonisation of animals and humans by ribotype 078 raises questions about possible zoonotic transmission, and also the diversity of reservoirs for ribotype 078 strains within the environment. One of the key factors which enables C. difficile to be a successful, highly transmissible pathogen is its ability to produce oxygen resistant spores capable of surviving harsh conditions. Here we describe the existence of a non-sporulating variant of C. difficile ribotype 078 harbouring mutations leading to premature stop codons within the master regulator, Spo0A. As sporulation is imperative to the successful transmission of C. difficile this study was undertaken to investigate phenotypic characteristics of this asporogenous phenotype with regards to growth rate, antibiotic susceptibility, toxin production and biofilm formation.The work was supported by the Department for Employment and Learning, Northern Irelan
Research Note: A comparison of media for the recovery of Campylobacter spp. from long term storage at -80° C
Get PDFPublication history: Accepted - 23 May 2017; Published - 2019.Pure cultures of Campylobacter spp. can be stored at -80°C for extended periods,
however they eventually lose viability. To maintain cultures regular resuscitation and subculturing
of strains needs to be undertaken but this requires that staff and media are available
for this purpose. Financial pressures on many institutes have had the consequence that regular
sub-culturing has become a financial burden.
Accordingly this study was undertaken to compare the ability of inexpensive media to
recover campylobacters from storage of up to 12 years at -80°C. Brain heart infusion agar
and modified charcoal cefoperazone deoxycholate agar base were compared with blood agar.
Overall, blood agar was found to be the best medium for this purpose and is to be
recommended.This project was funded by the Society for
Applied Microbiology, under the auspices of the
Students and Graduates into Work Programme
Field Evaluation of Deltamethrin and Ivermectin Applications to Cattle on Culicoides Host-Alighting, Blood-Feeding, and Emergence
Get PDFPublication history: accepted - 2 August 2019, published - 8 August 2019The impact of topical applications of deltamethrin and ivermectin to cattle on Culicoides spp. landing and blood-feeding was studied in this work using sticky traps mounted on Friesian heifers’ backs. There was no effect of the insecticides on total numbers of Culicoides trapped or the proportion engorged. Deltamethrin and ivermectin treatment did not prevent blood-feeding on these animals. Deltamethrin did result in significant Culicoides mortality as evidenced by the numbers of dead midges combed from heifers’ upper flanks. The proximity of engorged midges on traps to dead midges in the hair suggests that blood-feeding took place despite midges receiving an ultimately lethal dose of deltamethrin. Ivermectin application resulted in a smaller proportion of nulliparous than parous females caught. There was no significant effect of ivermectin on the numbers of Culicoides that emerged from dung samples (but p was small at 0.095 for the Obsoletus group Culicoides). In cases of suspect animal imports, pour-on or spray applications of deltamethrin could reduce the risk of onward transmission of bluetongue virus.This project was funded by the Department of Agriculture, Environment and Rural Affairs (Northern Ireland) through the Evidence and Innovation Strategy (Project 16/3/07-48109)
Strong and recurring seasonality revealed within stream diatom assemblages
Get PDFImproving stream water quality in agricultural landscapes is an ecological priority and a legislative duty for many governments. Ecosystem health can be effectively characterised by organisms sensitive to water quality changes such as diatoms, single-celled algae that are a ubiquitous component of stream benthos. Diatoms respond within daily timescales to variables including light, temperature, nutrient availability and flow conditions that result from weather and land use characteristics. However, little consideration has been given to the ecological dynamics of diatoms through repeated seasonal cycles when assessing trajectories of stream function, even in catchments actively managed to reduce human pressures. Here, six years of monthly diatom samples from three independent streams, each receiving differing levels of diffuse agricultural pollution, reveal robust and repeated seasonal variation. Predicted seasonal changes in climate-related variables and anticipated ecological impacts must be fully captured in future ecological and water quality assessments, if the apparent resistance of stream ecosystems to pollution mitigation measures is to be better understood
Determination of nucleotide and enzyme degradation in haddock (Melanogrammus aeglefinus) and herring (Clupea harengus) after high pressure processing
Get PDFPublication history: Accepted - 22 July 2019, Published - 27 August 2019Background
The degradation of nucleotides and their enzymes had been widely used to evaluate fish freshness. Immediately after fish death, adenosine triphosphate (ATP) degrades into inosine-5-monophosphate (IMP) via adenosine-5-diphosphate (ADP) and adenosine-5-monophosphate (AMP). IMP degradation continues to produce inosine (ino) and hypoxanthine (Hx) and further deteriorates the fish by producing xanthine and uric acid. The dephosphorylation of IMP to Ino is carried out by the enzyme 5′-nucleotidase (5′-NT), whereas the degradation of Ino to Hx is carried out by the enzyme nucleoside phosphorylase (NP). This study assesses the application of high pressure processing (HPP) in two species of fishes; haddock (Melanogrammus aeglefinus) and herring (Clupea harengus) as a means to extend the shelf-life by slowing down the rate of nucleotides degradation.
Methods
Haddock (Melanogrammus aeglefinus) and herring (Clupea harengus) fillets were subjected to HPP at 200, 250 and 300 MPa for 1 and 3 min before being stored for 14 days. In addition, 5′-NT and NP enzyme activities were determined on both fish species that were subjected to 100–600 MPa for 1 and 3 min.
Results
Adenosine triphosphate, ADP and AMP in both haddock and herring were lower at higher pressure levels. Inosine (Ino) increased (p 0.05) affected by the pressure treatment. H values are ratio of Hx to the sum of IMP, Ino and Hx. H values in haddock were significantly decreased (p 0.05) after pressure treatment. Furthermore, K values in control herring were significantly higher (p 0.05) after pressure treatment. Pressure treatment brought a significant decrease (p < 0.05) in protein content in both haddock and herring. 5′-NT activity was 20–35 fold higher compared to NP activity in haddock and 15–44 fold higher than NP activity in herring. 5′-NT and NP activities decreased significantly with increasing pressure level in both species.
Discussion
High pressure processing effectively slows down the conversion of Ino to Hx, delaying the undesirable flavour that develops in spoiling fish. The autolytic conversion of IMP to Ino by endogenous 5′-NT predominates in the earliest stages of storage is an autolytic process. However, both bacterial and endogenous NP enzymes are probably responsible for the gradual accumulation of Hx in fish. K values are recommended as a useful measurement of fish freshness.Funding
This work was supported by the Ministry of Education, Malaysia and Universiti Malaysia
Terengganu. The funders had no role in study design, data collection and analysis, decision
to publish, or preparation of the manuscript.
Grant Disclosures
The following grant information was disclosed by the authors:
Ministry of Education, Malaysia and Universiti Malaysia Terengganu
Drought decreases incorporation of recent plant photosynthate into soil food webs regardless of their trophic complexity
Get PDFPublication history: Accepted - 18 June 2019, Published - 13 July 2019.Theory suggests that more complex food webs promote stability and can buffer the effects of perturbations, such as drought, on soil organisms and ecosystem functions. Here, we tested experimentally how soil food web trophic complexity modulates the response to drought of soil functions related to carbon cycling and the capture and transfer below‐ground of recent photosynthate by plants. We constructed experimental systems comprising soil communities with one, two or three trophic levels (microorganisms, detritivores and predators) and subjected them to drought. We investigated how food web trophic complexity in interaction with drought influenced litter decomposition, soil CO2 efflux, mycorrhizal colonization, fungal production, microbial communities and soil fauna biomass. Plants were pulse‐labelled after the drought with 13C‐CO2 to quantify the capture of recent photosynthate and its transfer below‐ground. Overall, our results show that drought and soil food web trophic complexity do not interact to affect soil functions and microbial community composition, but act independently, with an overall stronger effect of drought. After drought, the net uptake of 13C by plants was reduced and its retention in plant biomass was greater, leading to a strong decrease in carbon transfer below‐ground. Although food web trophic complexity influenced the biomass of Collembola and fungal hyphal length, 13C enrichment and the net transfer of carbon from plant shoots to microbes and soil CO2 efflux were not affected significantly by varying the number of trophic groups. Our results indicate that drought has a strong effect on above‐ground–below‐ground linkages by reducing the flow of recent photosynthate. Our results emphasize the sensitivity of the critical pathway of recent photosynthate transfer from plants to soil organisms to a drought perturbation, and show that these effects may not be mitigated by the trophic complexity of soil communities, at least at the level manipulated in this experiment.Natural Environment Research Council. Grant Number: NE/M017028/
Experimental challenge with bovine respiratory syncytial virus in dairy calves: bronchial lymph node transcriptome response
Get PDFPublication history: Accepted - 19 September 2019; Published online - 14 October 2019.Bovine Respiratory Disease (BRD) is the leading cause of mortality in calves. The objective of this study
was to examine the response of the host’s bronchial lymph node transcriptome to Bovine Respiratory
Syncytial Virus (BRSV) in a controlled viral challenge. Holstein-Friesian calves were either inoculated
with virus (103.5 TCI D50/ml × 15 ml) (n = 12) or mock challenged with phosphate buffered saline (n = 6).
Clinical signs were scored daily and blood was collected for haematology counts, until euthanasia at day
7 post-challenge. RNA was extracted and sequenced (75 bp paired-end) from bronchial lymph nodes.
Sequence reads were aligned to the UMD3.1 bovine reference genome and differential gene expression
analysis was performed using EdgeR. There was a clear separation between BRSV challenged and
control calves based on gene expression changes, despite an observed mild clinical manifestation
of the disease. Therefore, measuring host gene expression levels may be beneficial for the diagnosis
of subclinical BRD. There were 934 differentially expressed genes (DEG) (p < 0.05, FDR <0.1, fold
change >2) between the BRSV challenged and control calves. Over-represented gene ontology terms,
pathways and molecular functions, among the DEG, were associated with immune responses. The
top enriched pathways included interferon signaling, granzyme B signaling and pathogen pattern
recognition receptors, which are responsible for the cytotoxic responses necessary to eliminate the
virus.This project was funded by the Irish Department of Agriculture and the Department of Agriculture, Environment
and Rural Affairs, Northern Ireland, as part of the US-Ireland R&D partnership call (RMIS_0033 Project 16/
RD/US-ROI/11). JFT and JWK were supported by Grant Number 2017-67015-26760 from the United States
Department for Agriculture National Institute for Food and Agriculture
An association analysis of sow parity, live-weight and back-fat depth as indicators of sow productivity
Get PDFPublication history: Accepted - 4 June 2018; Published online - 18 July 2018;
Published - March 2019.Understanding how critical sow live-weight and back-fat depth during gestation are in ensuring optimum sow productivity is
important. The objective of this study was to quantify the association between sow parity, live-weight and back-fat depth
during gestation with subsequent sow reproductive performance. Records of 1058 sows and 13 827 piglets from 10 trials on
two research farms between the years 2005 and 2015 were analysed. Sows ranged from parity 1 to 6 with the number of sows
per parity distributed as follows: 232, 277, 180, 131, 132 and 106, respectively. Variables that were analysed included total born
(TB), born alive (BA), piglet birth weight (BtWT), pre-weaning mortality (PWM), piglet wean weight (WnWT), number of piglets
weaned (Wn), wean to service interval (WSI), piglets born alive in subsequent farrowing and sow lactation feed intake.
Calculated variables included the within-litter CV in birth weight (LtV), pre-weaning growth rate per litter (PWG), total litter
gain (TLG), lactation efficiency and litter size reared after cross-fostering. Data were analysed using linear mixed models
accounting for covariance among records. Third and fourth parity sows had more (P<0.05) TB, BA and heavier BtWT compared
with gilts and parity 6 sow contemporaries. Parities 2 and 3 sows weaned more (P<0.05) piglets than older sows. These
piglets had heavier (P<0.05) birth weights than those from gilt litters. LtV and PWM were greater (P<0.01) in litters born to
parity 5 sows than those born to younger sows. Sow live-weight and back-fat depth at service, days 25 and 50 of gestation
were not associated with TB, BA, BtWT, LtV, PWG, WnWT or lactation efficiency (P>0.05). Heavier sow live-weight throughout
gestation was associated with an increase in PWM (P<0.01) and reduced Wn and lactation feed intake (P<0.05). Deeper
back-fat in late gestation was associated with fewer (P<0.05) BA but heavier (P<0.05) BtWT, whereas deeper back-fat
depth throughout gestation was associated with reduced (P<0.01) lactation feed intake. Sow back-fat depth was not
associated with LtV, PWG, TLG, WSI or piglets born alive in subsequent farrowing (P>0.05). In conclusion, this study showed
that sow parity, live-weight and back-fat depth can be used as indicators of reproductive performance. In addition, this study
also provides validation for future development of a benchmarking tool to monitor and improve the productivity of modern
sow herd.Department of Agriculture, Food and the Marine, Ireland (DAFM),
University of Leeds
Forewarned is forearmed: harmonized approaches for early detection of potentially invasive pests and pathogens in sentinel plantings
Get PDFPublication history: Accepted - 8 May 2019; Published - 21 June 2019.The number of invasive alien pest and pathogen species affecting ecosystem functioning, human health and economies has increased dramatically over the last decades. Discoveries of invasive pests and pathogens previously unknown to science or with unknown host associations yet damaging on novel hosts highlights the necessity of developing novel tools to predict their appearance in hitherto naive environments. The use of sentinel plant systems is a promising tool to improve the detection of pests and pathogens before introduction and to provide valuable information for the development of preventative measures to minimize economic or environmental impacts. Though sentinel plantings have been established and studied during the last decade, there still remains a great need for guidance on which tools and protocols to put into practice in order to make assessments accurate and reliable. The sampling and diagnostic protocols chosen should enable as much information as possible about potential damaging agents and species identification. Consistency and comparison of results are based on the adoption of common procedures for sampling design and sample processing. In this paper, we suggest harmonized procedures that should be used in sentinel planting surveys for effective sampling and identification of potential pests and pathogens. We also review the benefits and limitations of various diagnostic methods for early detection in sentinel systems, and the feasibility of the results obtained supporting National Plant Protection Organizations in pest and commodity risk analysis.This work was supported by COST Action Global Warning (FP1401). DLM and YB
contribution was also supported by the Russian Foundation for Basic Research (Grant
No. 17-04-01486). MG was supported by Ministry of Education, Science and Technological Development of the Republic of Serbia, Grant III43002. MKA was supported by the Ministry of Science and Higher Education of the Republic of Poland. NK was supported by Le Studium foundation (France) and RFBR (Grant No. 19-04-01029). RE, IF and MK contribution was also supported by CABI with core financial support from its member countries (see http://www.cabi.org/about-cabi/who-we-work-with/key-donors/
for details). IF contribution was further supported through a grant from the Swiss State
Secretariat for Science, Education and Research (Grant C15.0081, awarded to RE)