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The cuticles of ecdysozoan animals are barriers to material loss and xenobiotic insult. Key to this barrier is lipid content, the establishment of which is poorly understood. Here, we show that the p-glycoprotein PGP-14 functions coincidently with the sphingomyelin synthase SMS-5 to establish a polar lipid barrier within the pharyngeal cuticle of the nematode C. elegans. We show that PGP-14 and SMS-5 are coincidentally expressed in the epithelium that surrounds the anterior pharyngeal cuticle where PGP-14 localizes to the apical membrane. pgp-14 and sms-5 also peak in expression at the time of new cuticle synthesis. Loss of PGP-14 and SMS-5 dramatically reduces pharyngeal cuticle staining by Nile Red, a key marker of polar lipids, and coincidently alters the nematode's response to a wide-range of xenobiotics. We infer that PGP-14 exports polar lipids into the developing pharyngeal cuticle in an SMS-5-dependent manner to safeguard the nematode from environmental insult.
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Proteínas de Caenorhabditis elegans , Caenorhabditis elegans , Animales , Caenorhabditis elegans/genética , Caenorhabditis elegans/metabolismo , Membrana Celular/metabolismo , Proteínas de Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/metabolismo , Lípidos , PermeabilidadRESUMEN
BACKGROUND AND AIMS: Transcriptome sequencing is a cost-effective approach that allows researchers to study a broad range of questions. However, to preserve RNA for transcriptome sequencing, tissue is often kept in special conditions, such as immediate ultracold freezing. Here, we demonstrate that RNA can be obtained from 6-month-old, field-collected samples stored in silica gel at room temperature. Using these transcriptomes, we explore the evolutionary relationships of the genus Pitcairnia (Bromeliaceae) in the Dominican Republic and infer barriers to gene flow. METHODS: We extracted RNA from silica-dried leaf tissue from 19 Pitcairnia individuals collected across the Dominican Republic. We used a series of macro- and micro-evolutionary approaches to examine the relationships and patterns of gene flow among individuals. KEY RESULTS: We produced high-quality transcriptomes from silica-dried material and demonstrated that evolutionary relationships on the island match geography more closely than species delimitation methods. A population genetic examination indicates that a combination of ecological and geographical features presents barriers to gene flow in Pitcairnia. CONCLUSIONS: Transcriptomes can be obtained from silica-preserved tissue. The genetic diversity among Pitcairnia populations does not warrant classification as separate species, but the Dominican Republic contains several barriers to gene flow, notably the Cordillera Central mountain range.
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Flujo Génico , Transcriptoma , Humanos , Transcriptoma/genética , Región del Caribe , Hojas de la Planta/genética , ARNRESUMEN
INTRODUCTION: Academic medical centres (AMCs) have the tripartite mission of performing research to advance healthcare delivery, educating future clinicians and providing healthcare services. This study investigates the criteria associated with being promoted in a Singaporean AMC. METHODS: Using a dataset of 255 candidates for promotion at the studied AMC, we employ logistic regression to determine if these factors are associated with the likelihood of promotion. Further, we use interaction effects to test if the relationship between the H-index and likelihood of promotion differs across the academic levels of the candidates. RESULTS: The logistic regression results based on the best of our three tested models suggest that the H-index is positively associated with promotion for those applying to become clinical associate professors (OR=1.43, p=0.01). Moreover, candidates who provide well-developed education portfolios (OR=3.61, p=0.02) and who have held service/leadership roles (OR=6.72, p<0.001) are more likely to be promoted. CONCLUSIONS: This study affirms the correlation between promotion and the advancement criteria outlined by the AMC. This is important for transparency and trust between the AMC and its faculty in their applications for promotion and success in an academic career. Further, our study is one of the few empirical studies linking promotion criteria to promotion outcomes.
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OBJECTIVE: The academic medical centre (AMC), with over 2200 faculty members, annually manages approximately 300 appointments and promotions. Considering these large numbers, we explored whether machine learning could predict the probability of obtaining promotional approvals. METHODS: We examined variables related to academic promotion using predictive analytical methods. The data included candidates' publications, the H-index, educational contributions and leadership or service within and outside the AMC. RESULTS: Of the five methods employed, the random forest algorithm was identified as the 'best' model through our leave-one-out cross-validation model evaluation process. CONCLUSIONS: To the best of our knowledge, this is the first study on the AMC. The developed model can be deployed as a 'calculator' to evaluate faculty performance and assist applicants in understanding their chances of promotion based on historical data. Furthermore, it can act as a guide for tenure and promotion committees in candidate review processes. This increases the transparency of the promotion process and aligns faculty aspirations with the AMC's mission and vision. It is possible for other researchers to adopt the algorithms from our analysis and apply them to their data.
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Colourful spots, stripes and rings decorate the corolla of most flowering plants and fulfil important biotic and abiotic functions. Spatial differences in the pigmentation of epidermal cells can create these patterns. The last few years have yielded new data that have started to illuminate the mechanisms controlling the function, formation and evolution of petal patterns. These advances have broad impacts beyond the immediate field as pigmentation patterns are wonderful systems to explore multiscale biological problems: from understanding how cells make decisions at the microscale to examining the roots of biodiversity at the macroscale. These new results also reveal there is more to petal patterning than meets the eye, opening up a brand new area of investigation. In this mini-review, we summarise our current knowledge on the Eco-Evo-Devo of petal pigmentation patterns and discuss some of the most exciting yet unanswered questions that represent avenues for future research.
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An amendment to this paper has been published and can be accessed via a link at the top of the paper.
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The nematode Caenorhabditis elegans is a bacterivore filter feeder. Through the contraction of the worm's pharynx, a bacterial suspension is sucked into the pharynx's lumen. Excess liquid is then shunted out of the buccal cavity through ancillary channels made by surrounding marginal cells. We find that many worm-bioactive small molecules (a.k.a. wactives) accumulate inside of the marginal cells as crystals or globular spheres. Through screens for mutants that resist the lethality associated with one crystallizing wactive we identify a presumptive sphingomyelin-synthesis pathway that is necessary for crystal and sphere accumulation. We find that expression of sphingomyelin synthase 5 (SMS-5) in the marginal cells is not only sufficient for wactive accumulation but is also important for absorbing exogenous cholesterol, without which C. elegans cannot develop. We conclude that sphingomyelin-rich marginal cells act as a sink to scavenge important nutrients from filtered liquid that might otherwise be shunted back into the environment.
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Caenorhabditis elegans/metabolismo , Colesterol/metabolismo , Faringe/metabolismo , Esfingomielinas/metabolismo , Animales , Bacterias/metabolismo , Caenorhabditis elegans/citología , Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/metabolismo , Membrana Celular/metabolismo , Cristalización , Interacciones Hidrofóbicas e Hidrofílicas , Mutación , Faringe/citología , Esfingomielinas/química , Transferasas (Grupos de Otros Fosfatos Sustitutos)/genética , Transferasas (Grupos de Otros Fosfatos Sustitutos)/metabolismoRESUMEN
Parasitic nematodes negatively impact human and animal health worldwide. The market withdrawal of nematicidal agents due to unfavourable toxicities has limited the available treatment options. In principle, co-administering nematicides at lower doses along with molecules that potentiate their activity could mitigate adverse toxicities without compromising efficacy. Here, we screened for new small molecules that interact with aldicarb, which is a highly effective treatment for plant-parasitic nematodes whose toxicity hampers its utility. From our collection of 638 worm-bioactive compounds, we identified 20 molecules that interact positively with aldicarb to either kill or arrest the growth of the model nematode Caenorhabditis elegans. We investigated the mechanism of interaction between aldicarb and one of these novel nematicides called wact-86. We found that the carboxylesterase enzyme GES-1 hydrolyzes wact-86, and that the interaction is manifested by aldicarb's inhibition of wact-86's metabolism by GES-1. This work demonstrates the utility of C. elegans as a platform to search for new molecules that can positively interact with industrial nematicides, and provides proof-of-concept for prospective discovery efforts.
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Aldicarb/farmacología , Antinematodos/farmacología , Benzamidas/farmacología , Benzofuranos/farmacología , Proteínas de Caenorhabditis elegans/genética , Caenorhabditis elegans/efectos de los fármacos , Hidrolasas de Éster Carboxílico/genética , Nematodos/efectos de los fármacos , Secuencia de Aminoácidos , Animales , Antinematodos/química , Proteínas de Caenorhabditis elegans/antagonistas & inhibidores , Hidrolasas de Éster Carboxílico/antagonistas & inhibidores , Mutación , Alineación de SecuenciaRESUMEN
Parasitic nematodes infect one quarter of the world's population and impact all humans through widespread infection of crops and livestock. Resistance to current anthelmintics has prompted the search for new drugs. Traditional screens that rely on parasitic worms are costly and labour intensive and target-based approaches have failed to yield novel anthelmintics. Here, we present our screen of 67,012 compounds to identify those that kill the non-parasitic nematode Caenorhabditis elegans. We then rescreen our hits in two parasitic nematode species and two vertebrate models (HEK293 cells and zebrafish), and identify 30 structurally distinct anthelmintic lead molecules. Genetic screens of 19 million C. elegans mutants reveal those nematicides for which the generation of resistance is and is not likely. We identify the target of one lead with nematode specificity and nanomolar potency as complex II of the electron transport chain. This work establishes C. elegans as an effective and cost-efficient model system for anthelmintic discovery.