scholarly journals More Is Not Always Better: Coinfections with Defensive Symbionts Generate Highly Variable Outcomes

2019 ◽  
Vol 86 (5) ◽  
Author(s):  
S. R. Weldon ◽  
J. A. Russell ◽  
K. M. Oliver
Keyword(s):  
Acyrthosiphon Pisum ◽  
Natural Infection ◽  
Poor Performance ◽  
Single Infection ◽  
Content Type ◽  
Pea Aphids ◽  
Low Diversity ◽  
Hamiltonella Defensa ◽  
To Receive ◽  
Pathogen Exposure

ABSTRACT Animal-associated microbes are highly variable, contributing to a diverse set of symbiont-mediated phenotypes. Given that host and symbiont genotypes, and their interactions, can impact symbiont-based phenotypes across environments, there is potential for extensive variation in fitness outcomes. Pea aphids, Acyrthosiphon pisum, host a diverse assemblage of heritable facultative symbionts (HFS) with characterized roles in host defense. Protective phenotypes have been largely studied as single infections, but pea aphids often carry multiple HFS species, and particular combinations may be enriched or depleted compared to expectations based on chance. Here, we examined the consequences of single infection versus coinfection with two common HFS exhibiting variable enrichment, the antiparasitoid Hamiltonella defensa and the antipathogen Regiella insecticola, across three host genotypes and environments. As expected, single infections with either H. defensa or R. insecticola raised defenses against their respective targets. Single infections with protective H. defensa lowered aphid fitness in the absence of enemy challenge, while R. insecticola was comparatively benign. However, as a coinfection, R. insecticola ameliorated H. defensa infection costs. Coinfected aphids continued to receive antiparasitoid protection from H. defensa, but protection was weakened by R. insecticola in two clones. Notably, H. defensa eliminated survival benefits conferred after pathogen exposure by coinfecting R. insecticola. Since pathogen sporulation was suppressed by R. insecticola in coinfected aphids, the poor performance likely stemmed from H. defensa-imposed costs rather than weakened defenses. Our results reveal a complex set of coinfection outcomes which may partially explain natural infection patterns and suggest that symbiont-based phenotypes may not be easily predicted based solely on infection status. IMPORTANCE The hyperdiverse arthropods often harbor maternally transmitted bacteria that protect against natural enemies. In many species, low-diversity communities of heritable symbionts are common, providing opportunities for cooperation and conflict among symbionts, which can impact the defensive services rendered. Using the pea aphid, a model for defensive symbiosis, we show that coinfections with two common defensive symbionts, the antipathogen Regiella and the antiparasite Hamiltonella, produce outcomes that are highly variable compared to single infections, which consistently protect against designated enemies. Compared to single infections, coinfections often reduced defensive services during enemy challenge yet improved aphid fitness in the absence of enemies. Thus, infection with multiple symbionts does not necessarily create generalist aphids with “Swiss army knife” defenses against numerous enemies. Instead, particular combinations of symbionts may be favored for a variety of reasons, including their abilities to lessen the costs of other defensive symbionts when enemies are not present.

scholarly journals Aphid Heritable Symbiont Exploits Defensive Mutualism

2017 ◽  
Vol 83 (8) ◽  
Author(s):  
Matthew R. Doremus ◽  
Kerry M. Oliver
Keyword(s):  
Fungal Pathogens ◽  
Acyrthosiphon Pisum ◽  
Pea Aphid ◽  
Single Infection ◽  
Community Members ◽  
Content Type ◽  
Defensive Mutualism ◽  
Potential Alternative ◽  
Hamiltonella Defensa ◽  
Alternative Routes

ABSTRACT Insects and other animals commonly form symbioses with heritable bacteria, which can exert large influences on host biology and ecology. The pea aphid, Acyrthosiphon pisum, is a model for studying effects of infection with heritable facultative symbionts (HFS), and each of its seven common HFS species has been reported to provide resistance to biotic or abiotic stresses. However, one common HFS, called X-type, rarely occurs as a single infection in field populations and instead typically superinfects individual aphids with Hamiltonella defensa, another HFS that protects aphids against attack by parasitic wasps. Using experimental aphid lines comprised of all possible infection combinations in a uniform aphid genotype, we investigated whether the most common strain of X-type provides any of the established benefits associated with aphid HFS as a single infection or superinfection with H. defensa. We found that X-type does not confer protection to any tested threats, including parasitoid wasps, fungal pathogens, or thermal stress. Instead, component fitness assays identified large costs associated with X-type infection, costs which were ameliorated in superinfected aphids. Together these findings suggest that X-type exploits the aphid/H. defensa mutualism and is maintained primarily as a superinfection by “hitchhiking” via the mutualistic benefits provided by another HFS. Exploitative symbionts potentially restrict the functions and distributions of mutualistic symbioses with effects that extend to other community members. IMPORTANCE Maternally transmitted bacterial symbionts are widespread and can have major impacts on the biology of arthropods, including insects of medical and agricultural importance. Given that host fitness and symbiont fitness are tightly linked, inherited symbionts can spread within host populations by providing beneficial services. Many insects, however, are frequently infected with multiple heritable symbiont species, providing potential alternative routes of symbiont maintenance. Here we show that a common pea aphid symbiont called X-type likely employs an exploitative strategy of hitchhiking off the benefits of a protective symbiont, Hamiltonella. Infection with X-type provides none of the benefits conferred by other aphid symbionts and instead results in large fitness costs, costs lessened by superinfection with Hamiltonella. These findings are corroborated by natural infections in field populations, where X-type is mostly found superinfecting aphids with Hamiltonella. Exploitative symbionts may be common in hosts with communities of heritable symbionts and serve to hasten the breakdown of mutualisms.

Why suppliers struggle to deliver defect-free products to buyers: a buyer–supplier dyadic perspective

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Imranul Hoque
Keyword(s):  
Quality Control ◽  
Qualitative Data ◽  
Resistance To Change ◽  
Poor Performance ◽  
Research Approach ◽  
Free Products ◽  
Content Type ◽  
Root Cause ◽  
Holistic Understanding ◽  
To Receive

PurposeThis study explores the challenges of garment suppliers in delivering defect-free products to their buyers and how buyers play a role in overcoming the challenges.Design/methodology/approachFollowing a qualitative research approach and a multiple case study method, quantitative and qualitative data were collected from the four garment suppliers and buyer's representatives. Both quantitative and qualitative data analysis techniques were applied to understand the challenges in delivering defect-free products.FindingsThe study findings show that garment suppliers' main challenges in delivering defect-free products are unsystematic quality control, informal root cause analysis, limited education and training facilities, dearth of a learning culture, limited quality control capability, lack of cross-functional team, inadequate modern technologies, workers' resistance to change and poor performance evaluation. Moreover, this study demonstrates how buyers can enhance their support to suppliers to receive defect-free products.Research limitations/implicationsWhereas the garment industry has more than four thousand suppliers, this study considers only four suppliers. Therefore, the generalisability of the study may be questioned. Furthermore, as this study considers only a single sewing line in each factory, future studies could incorporate more lines for a holistic understanding.Practical implicationsThe findings of this study could help the managers of supplier firms understand how to tackle the hurdles of defect-free garment production and give buyers a guideline about what role they need to play to receive defect-free garments from suppliers.Originality/valueFor the first time, this study presents how garment suppliers and their lead buyers play significant roles in satisfying end consumers' demand by overcoming the challenges of defect-free garment production.

scholarly journals Factors Limiting the Spread of the Protective Symbiont Hamiltonella defensa in Aphis craccivora Aphids

2014 ◽  
Vol 80 (18) ◽  
pp. 5818-5827 ◽  
Author(s):  
Hannah R. Dykstra ◽  
Stephanie R. Weldon ◽  
Adam J. Martinez ◽  
Jennifer A. White ◽  
Keith R. Hopper ◽  
...  
Keyword(s):  
Acyrthosiphon Pisum ◽  
Aphis Craccivora ◽  
Content Type ◽  
Transmission Rates ◽  
Real Time Quantitative Pcr ◽  
Host Protection ◽  
Multiple Loci ◽  
Infection Dynamics ◽  
Hamiltonella Defensa ◽  
Protection Profile

ABSTRACTMany insects are associated with heritable symbionts that mediate ecological interactions, including host protection against natural enemies. The cowpea aphid,Aphis craccivora, is a polyphagous pest that harborsHamiltonella defensa, which defends against parasitic wasps. Despite this protective benefit, this symbiont occurs only at intermediate frequencies in field populations. To identify factors constrainingH. defensainvasion inAp. craccivora, we estimated symbiont transmission rates, performed fitness assays, and measured infection dynamics in population cages to evaluate effects of infection. Similar to results with the pea aphid,Acyrthosiphon pisum, we found no consistent costs to infection using component fitness assays, but we did identify clear costs to infection in population cages when no enemies were present. Maternal transmission rates ofH. defensainAp. craccivorawere high (ca. 99%) but not perfect. Transmission failures and infection costs likely limit the spread of protectiveH. defensainAp. craccivora. We also characterized several parameters ofH. defensainfection potentially relevant to the protective phenotype. We confirmed the presence ofH. defensain aphid hemolymph, where it potentially interacts with endoparasites, and performed real-time quantitative PCR (qPCR) to estimate symbiont and phage abundance during aphid development. We also examined strain variation ofH. defensaand its bacteriophage at multiple loci, and despite our lines being collected in different regions of North America, they were infected with a nearly identical strains ofH. defensaand APSE4 phage. The limited strain diversity observed for these defensive elements may result in relatively static protection profile for this defensive symbiosis.

scholarly journals Cultivation-assisted genome of Candidatus Fukatsuia symbiotica; the enigmatic ‘X-type’ symbiont of aphids

2019 ◽  
Author(s):  
V Patel ◽  
G Chevignon ◽  
A Manzano-Marín ◽  
J W Brandt ◽  
M R Strand ◽  
...  
Keyword(s):  
Acyrthosiphon Pisum ◽  
Host Cells ◽  
Mobile Dna ◽  
Recent Event ◽  
Genomic Signatures ◽  
Terrestrial Arthropods ◽  
Obligate Symbiont ◽  
Pea Aphids ◽  
Hamiltonella Defensa

Abstract Heritable symbionts are common in terrestrial arthropods and often provide beneficial services to hosts. Unlike obligate, nutritional symbionts that largely persist under strict host control within specialized host cells, heritable facultative symbionts exhibit large variation in within-host lifestyles and services rendered with many retaining the capacity to transition among roles. One enigmatic symbiont, Candidatus Fukatsuia symbiotica, frequently infects aphids with reported roles ranging from pathogen, defensive symbiont, mutualism exploiter and nutritional co-obligate symbiont. Here we used an in vitro culture-assisted protocol to sequence the genome of a facultative strain of Fukatsuia from pea aphids (Acyrthosiphon pisum). Phylogenetic and genomic comparisons indicate that Fukatsuia is an aerobic heterotroph, which together with Regiella insecticola and Hamiltonella defensa form a clade of heritable facultative symbionts within the Yersiniaceae (Enterobacteriales). These three heritable facultative symbionts largely share overlapping inventories of genes associated with housekeeping functions, metabolism, and nutrient acquisition, while varying in complements of mobile DNA. One unusual feature of Fukatsuia is its strong tendency to occur as a co-infection with H. defensa. However, the overall similarity of gene inventories among aphid heritable facultative symbionts suggest that metabolic complementarity is not the basis for co-infection, unless playing out on a H. defensa strain-specific basis. We also compared the pea aphid Fukatsuia with a strain from the aphid Cinara confinis (Lachninae) where it is reported to have transitioned to co-obligate status to support decaying Buchnera function. Overall the two genomes are very similar with no clear genomic signatures consistent with such a transition, which suggests co-obligate status in C. confinis was a recent event.

scholarly journals Symbiont-Mediated Protection against Fungal Pathogens in Pea Aphids: a Role for Pathogen Specificity?

2013 ◽  
Vol 79 (7) ◽  
pp. 2455-2458 ◽  
Author(s):  
Benjamin J. Parker ◽  
Chelsea J. Spragg ◽  
Boran Altincicek ◽  
Nicole M. Gerardo
Keyword(s):  
Beauveria Bassiana ◽  
Fungal Pathogen ◽  
Fungal Pathogens ◽  
Acyrthosiphon Pisum ◽  
Agricultural Pest ◽  
Content Type ◽  
Pea Aphids ◽  
Fungal Entomopathogen ◽  
Generalist Insect ◽  
Complex Influence

ABSTRACTHere we show that a bacterial endosymbiont,Regiella insecticola, protects pea aphids (Acyrthosiphon pisum) from the aphid-specific fungal entomopathogenZoophthora occidentalisbut not from the generalist insect fungal pathogenBeauveria bassiana. This finding highlights the complex influence of fungi on the dynamics of this economically important agricultural pest.

scholarly journals Phase 1 Study of the Safety, Tolerability, and Pharmacokinetics of the β-Lactamase Inhibitor Vaborbactam (RPX7009) in Healthy Adult Subjects

2016 ◽  
Vol 60 (10) ◽  
pp. 6326-6332 ◽  
Author(s):  
David C. Griffith ◽  
Jeffery S. Loutit ◽  
Elizabeth E. Morgan ◽  
Stephanie Durso ◽  
Michael N. Dudley
Keyword(s):  
Plasma Clearance ◽  
Healthy Adult ◽  
Phase 1 ◽  
High Dose ◽  
Double Blind ◽  
Time Curve ◽  
Content Type ◽  
Multiple Doses ◽  
To Receive ◽  
Lactamase Inhibitor

ABSTRACTVaborbactam (formerly RPX7009) is a member of a new class of β-lactamase inhibitor with pharmacokinetic properties similar to those of many β-lactams, including carbapenems. The pharmacokinetics and safety of vaborbactam were evaluated in 80 healthy adult subjects in a first-in-human randomized, placebo-controlled, double-blind, sequential single- and multiple-ascending-dose study. A total of 10 dose cohorts were enrolled in the study, with 6 subjects randomized to receive 250 to 2,000 mg of vaborbactam and 2 subjects randomized to receive placebo in each cohort. Maximum concentrations for vaborbactam were achieved at the end of the 3-h infusion. Vaborbactam exposure (Cmaxand area under the concentration-time curve [AUC]) increased in a dose-proportional manner following multiple doses. There was no evidence of accumulation with multiple doses, consistent with the terminal half-life of ∼2 h. Both the volume of distribution (Vss) and plasma clearance were independent of dose. For the 2,000-mg dose, the plasma clearance was 0.17 ± 0.03 liters/h, the AUC from 0 h to infinity (AUC0–∞) was 144.00 ± 13.90 mg · h/liter, and theVsswas 21.80 ± 2.26 mg · h/liter. Urinary recovery was 80% or greater over 48 h across all dose groups. No subjects discontinued the study due to adverse events (AEs), and no serious AEs (SAEs) were observed. All AEs were mild to moderate and similar among the vaborbactam- and placebo-treated subjects, with mild lethargy as the only unique AE reported with the high dose of vaborbactam. Overall, this study revealed the safety, tolerability, and pharmacokinetic profile of vaborbactam and formed the basis for advancement into patient studies in combination with meropenem, including treatment of patients with carbapenem-resistantEnterobacteriaceae(CRE) infections. (This study is registered at ClinicalTrials.gov under identifier NCT01751269.)

scholarly journals Pharmacokinetic Interactions between Primaquine and Chloroquine

2014 ◽  
Vol 58 (6) ◽  
pp. 3354-3359 ◽  
Author(s):  
Sasithon Pukrittayakamee ◽  
Joel Tarning ◽  
Podjanee Jittamala ◽  
Prakaykaew Charunwatthana ◽  
Saranath Lawpoolsri ◽  
...  
Keyword(s):  
Oral Dose ◽  
Hospital Admissions ◽  
Geometric Mean ◽  
Pharmacokinetic Interaction ◽  
Plasmodium Ovale ◽  
Open Label ◽  
Content Type ◽  
Reference Number ◽  
Electrocardiographic Changes ◽  
To Receive

ABSTRACTChloroquine combined with primaquine has been the standard radical curative regimen forPlasmodium vivaxandPlasmodium ovalemalaria for over half a century. In an open-label crossover pharmacokinetic study, 16 healthy volunteers (4 males and 12 females) aged 20 to 47 years were randomized into two groups of three sequential hospital admissions to receive a single oral dose of 30 mg (base) primaquine, 600 mg (base) chloroquine, and the two drugs together. The coadministration of the two drugs did not affect chloroquine or desethylchloroquine pharmacokinetics but increased plasma primaquine concentrations significantly (P≤ 0.005); the geometric mean (90% confidence interval [CI]) increases were 63% (47 to 81%) in maximum concentration and 24% (13 to 35%) in total exposure. There were also corresponding increases in plasma carboxyprimaquine concentrations (P≤ 0.020). There were no significant electrocardiographic changes following primaquine administration, but there was slight corrected QT (QTc) (Fridericia) interval lengthening following chloroquine administration (median [range] = 6.32 [−1.45 to 12.3] ms;P< 0.001), which was not affected by the addition of primaquine (5.58 [1.74 to 11.4] ms;P= 0.642). This pharmacokinetic interaction may explain previous observations of synergy in preventingP. vivaxrelapse. This trial was registered at ClinicalTrials.gov under reference number NCT01218932.

Negotiating without the victim state: the exclusiveness of anticorruption settlements

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Nadja Capus ◽  
Kei Hannah Brodersen
Keyword(s):  
Case Studies ◽  
Design Methodology ◽  
Criminal Proceedings ◽  
International Guidelines ◽  
England And Wales ◽  
Content Type ◽  
The Past ◽  
Settlement Agreements ◽  
To Receive ◽  
Obligation To Inform

Purpose Corporate foreign bribery can have devastating consequences on communities and states. Over the past decade, there have been several promising developments, both national and international, that might increase the chances of victim states to receive remediation for the harm they suffered from foreign bribery. In particular, awareness has risen that victim states must be considered and new innovative items have been added to the toolbox of prosecutors in the fight against corruption that is assumed to also improve victim states’ standing in these procedures. This study aims to assess whether indeed victim states receive compensation through these novel procedures. Design/methodology/approach This study uses the three case studies of Switzerland, France and England and Wales for a comprehensive empirical and normative analysis of settlement agreements between defendants and prosecution authorities and of court jurisprudence. Findings This study shows that although de jure, it seems warranted to order the payment of remedies to victim states within domestic criminal proceedings, in practice, this rarely happens. A number of legal and practical obstacles account for this situation. This study, therefore, calls for the formulation of international guidelines containing the obligation to inform victim states of ongoing criminal proceedings on corporate foreign bribery, and guidance on how to identify the victim of this crime, as well as the damage caused. Originality/value This is the first contribution to verify whether claims that settlement agreements, recently introduced in England and Wales and France (and similar procedures are available in Switzerland), are beneficial for victim states in their quest to receive compensation. As this study shows that this is – not yet – the case in practice, this study proposes solutions that could lead the way for remediation of the harm caused by corporate corruption – and thereby, ultimately, to a more just outcome.

Designing an uncertain bi-objective green leagile capacitated lot sizing problem considering FM/M/C queue system

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Masoud Rabbani ◽  
Soroush Aghamohamadi Bosjin ◽  
Neda Manavizadeh ◽  
Hamed Farrokhi-Asl
Keyword(s):  
Mathematical Model ◽  
Solution Method ◽  
Lot Sizing ◽  
Test Problems ◽  
Content Type ◽  
Queue System ◽  
Proposed Model ◽  
Lot Sizing Problem ◽  
Capacitated Lot Sizing ◽  
To Receive

Purpose This paper aims to present a novel bi-objective mathematical model for a production-inventory system under uncertainty. Design/methodology/approach This paper addresses agile and lean manufacturing concepts alongside with green production methods to design an integrated capacitated lot sizing problem (CLSP). From a methodological perspective, the problem is solved in three phases. In the first step, an FM/M/C queuing system is used to minimize the number of customers waited to receive their orders. In the second step, an effective approach is applied to deal with the fuzzy bi-objective model and finally, a hybrid metaheuristic algorithm is used to solve the problem. Findings Some numerical test problems and sensitivity analyzes are conducted to measure the efficiency of the proposed model and the solution method. The results validate the model and the performance of the solution method compared to Gams results in small size test problems and prove the superiority of the hybrid algorithm in comparison with the other well-known metaheuristic algorithms in large size test problems. Originality/value This paper presents a novel bi-objective mathematical model for a CLSP under uncertainty. The proposed model is conducted on a practical case and several sensitivity analysis are conducted to assess the behavior of the model. Using a queue system, this problem aims to reduce the items waited in the queue to receive service. Two objective functions are considered to maximize the profit and minimize the negative environmental effects. In this regard, the second objective function aims to reduce the amount of emitted carbon.

Ascertaining the effectiveness of Economic and Financial Crimes Commission (EFCC) in tackling corruptions in Nigeria

2018 ◽  
Vol 25 (3) ◽  
pp. 658-668 ◽  
Author(s):  
Ibrahim Umar ◽  
Rose Shamsiah Samsudin ◽  
Mudzamir bn Mohamed
Keyword(s):  
Poor Performance ◽  
Organizational Factors ◽  
Content Type ◽  
Study Approach ◽  
Documentary Analysis ◽  
Current State ◽  
Financial Crimes ◽  
Lack Of Commitment ◽  
Depth Interviews

Purpose The purpose of this paper is to appraise the Nigerian Economic and Financial Crimes Commission (EFCC) of their role in tackling systemic corruptions and to associate how institutional and organizational factors influence the performance of the EFCC. Design/methodology/approach Data were gathered through in-depth interviews, non-participatory observations and documentary analysis. Findings The results of the integrative analysis show that the EFCC has apparently been ineffective, and further improvization of the organization is needed. Poor performance of the EFCC was associated with factors such as lack of commitment, inefficient judiciary, insufficient budgets and incompetent personnel. Practical implications This study recommends further improvements in the form of a greater political will, improved legal process and also elevated budgetary funds and recruitment of personnel to the EFCC. Originality/value The study adopted a descriptive, qualitative case study approach to describe the current state of the EFCC in Nigeria.

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