Biology subjects

Louis, J.

Publications and source records attributed to Louis, J..

7 recordsLinked to original sources

bioRxiv2026

Pharmacological modulation of ATP-binding cassette transporters alters feeding phases of the sugarcane aphid on susceptible sorghum

BACKGROUND: Aphids damage crops through sustained feeding and by rapid transmission of plant viruses, processes that are not effectively prevented by conventional insecticides. The sugarcane aphid (Melanaphis sacchari), an invasive pest of sorghum in the United States, can inoculate non-persistent viruses within minutes of probing. Disrupting feeding phases represents an alternative strategy in plant disease and integrated pest management. ATP-binding cassette transporters (ABC transporters) influence insect physiological performance, but their role in regulating aphid feeding behavior relevant to crop damage and virus transmission remains unknown. This study evaluated whether ABC transporter activity alters feeding phases of M. sacchari on sorghum. RESULTS: Aphids exposed to ABC transporter modulators via artificial diet and monitored using Electrical Penetration Graph (EPG) recordings showed significant reductions in salivation in E1 phase, compared with controls (P < 0.05) and an increased duration in xylem phase when treated with elacridar, an ABC transporter inhibitor. Aphids treated with dexamethasone, an ABC transporter activator, exhibited increased time spent in pathway phase compared to the controls. ATPase assays also showed significant variations in modulator-treated samples compared to the controls. CONCLUSION: These results demonstrate that transporter modulators alter feeding behaviors which might lead to reduced crop damage/virus transmission, including pathway activities, salivation, and xylem ingestion. This study opens the path to identify ABC transporters as regulators of feeding phases, and to advance the understanding of aphid-plant interactions. This new knowledge will support the development of feeding-based pest management strategies to reduce crop damage and virus transmission.

physiology↗

bioRxiv2024

Plant responses to wheat curl mites and wheat streak mosaic virus (WSMV): first evidence of virus tolerance in wheat

Wheat curl mites (WCM) are arthropod pests that pose significant threats to wheat crops by causing direct damage by feeding, and transmitting viruses such as Wheat Streak Mosaic Virus (WSMV), Triticum Mosaic Virus (TriMV), and High Plains Wheat Mosaic Virus (HPWMoV), leading to substantial losses in wheat, barley, oats, and rye. Over three years of field screening, we found that the cultivar Hatcher consistently produced higher yields under high WSMV disease pressure, outperforming Mace and TAM112, which carry the Wsm1 gene and a QTL for curl mite resistance, respectively, indicating tolerance. To investigate the mechanisms underlying the tolerance phenotype in Hatcher, we compared its response to WCM and WSMV infection with a susceptible genotype, CO15D173R. Transcriptomic analysis revealed a nuanced interplay between plant defense and growth in Hatcher, with upregulation of genes related to jasmonic acid (JA), salicylic acid (SA), and abscisic acid (ABA) pathways, indicating a coordinated defense response. The activation of lignin biosynthesis genes points to a potential role of cell wall strengthening in deterring WCM and WSMV. Additionally, the regulation of genes involved in growth-related hormonal pathways such as gibberellic acid (GA), and brassinosteroids (BR) highlights Hatchers ability to maintain growth disease pressure. Our findings provide insight into the intricate network of phytohormones, growth-defense trade-offs, and cell wall modifications contributing to Hatchers tolerance to WCM and WSMV. This knowledge can inform the development of tolerant wheat varieties and enhance integrated pest management strategies, ultimately safeguarding wheat production.

plant biology↗

bioRxiv2024

Turnover rates of human muscle proteins in vivo reported in fractional, mole and absolute units.

Protein fractional turnover rates (FTR) represent measurements of flux through a protein pool, i.e. net abundance (ABD) of the protein. If protein abundance is not measured or is different between experimental conditions the interpretation of FTR data may be confounded. This project investigates the consequences of reporting turnover rates of human muscle proteins in vivo in mole and absolute units (that incorporate protein abundance data) compared to fractional (%/d) data that ignore protein abundance. Three physically active males (21 {+/-} 1 years) were recruited and underwent a 12-d protocol of daily deuterium oxide (D2O) consumption and biopsies of vastus lateralis on days 8 and 12. Protein abundances were normalised to yeast alcohol dehydrogenase, added during sample preparation, and FTR was calculated from time-dependent changes in peptide mass isotopomer profiles. FTR and abundance data (fmol/ g protein) were combined to calculate mole turnover rates (MTR; fmol/ g protein/ d) and absolute turnover rates (ATR; ng/ g protein/ d). Abundance data were collected for 1,772 proteins and FTR data were calculated from 3,944 peptides representing 935 proteins (average 3 peptides per protein). The median (M), lower- (Q1) and upper-quartile (Q3) values for protein FTR (%/d) were M = 4.3, Q1 = 2.52, Q3 = 7.84. Our analyses suggest MTR data is preferred over FTR, particularly for studies on multiprotein complexes, wherein MTR takes account of potential differences amongst the molecular weight of the component subunits. ATR data may be preferred over MTR and FTR, particularly when comparing samples with different abundance profiles.

systems biology↗

bioRxiv2022

Nationwide assessment of leadership development for graduate students in the agricultural plant sciences

Leadership development is a universally important goal across the agricultural plant science disciplines. Although previous studies have identified a need for leadership skills, less is known about leadership skill development in graduate programs. To address this, we constructed a mixed-method study to identify the most significant graduate school leadership experiences of scientists in the agricultural plant science disciplines. The survey was deployed to 6,728 people in the U.S. and received 1,086 responses (16.1% response rate). The majority of respondents reported that they were from one of the major agricultural states and employed at one of the agricultural plant science related doctoral universities, industries, or government. Results from this survey suggest that recent graduates were more engaged in graduate school activities that offered leadership development. Key experiences in graduate school were also identified that may be used to develop future leaders. Additionally, respondents reported the greatest barrier to providing leadership development for graduate students was that it is not part of their program curriculum, however current graduate students responded differently, and identifying lack of funding to support experiences as the greatest barrier. This survey also identified the top ranked professional skills considered most important for effective leaders in agricultural plant sciences as well as respondent-driven recommendations on how graduate programs can improve leadership development. Collectively, these results can be used in the future to identify priorities for skill development and opportunities for graduate student training in leadership skills within the plant science disciplines.

scientific communication and education↗

bioRxiv2022

Interplay between MYZUS PERSICAE-INDUCED LIPASE 1 and OPDA signaling in controlling green peach aphid infestation on Arabidopsis thaliana

MYZUS PERSICAE-INDUCED LIPASE1 (MPL1) encodes a lipase in Arabidopsis thaliana that is required for controlling infestation by the green peach aphid (GPA; Myzus persicae), an important phloem sap-consuming insect pest. Previously, we demonstrated that MPL1 expression was upregulated in response to GPA infestation, and GPA fecundity was higher on the mpl1 mutant, compared to the wild-type (WT), and lower on 35S:MPL1 plants that constitutively expressed MPL1 from the 35S promoter. Here, we show that the MPL1 promoter is active in the phloem and expression of the MPL1 coding sequence from the phloem-specific SUC2 promoter is sufficient to restore resistance to the GPA in the mpl1 mutant. The GPA infestation-associated upregulation of MPL1 requires CYCLOPHILIN 20-3 (CYP20-3), which encodes a 12-oxo- phytodienoic acid (OPDA)-binding protein that is involved in OPDA signaling and is required for controlling GPA infestation. OPDA promotes MPL1 expression to limit GPA fecundity, a process that requires CYP20-3 function. These results along with our observation that constitutive expression of MPL1 from the 35S promoter restores resistance to the GPA in the cyp20-3 mutant, and MPL1 feedbacks to limit OPDA levels in GPA-infested plants, suggest that an interplay between MPL1, OPDA, and CYP20-3 contributes to resistance to the GPA. HighlightInteraction between MYZUS PERSICAE-INDUCED LIPASE 1 function in the phloem, and 12-oxo-phytodienoic acid (OPDA) and CYCLOPHILIN 20-3, which encodes an OPDA-binding protein that is involved in OPDA signaling, is involved in controlling green peach aphid infestation on Arabidopsis thaliana.

plant biology↗

bioRxiv2020

The dorsal striatum sets the sensitivity to effort

The dorsal striatum (dS) has been implicated in storing and retrieving procedural memories and controlling movement kinematics (e.g., speed). Since procedural memories are expressed through movements, the exact nature of the dS function has proven difficult to delineate. Here we challenged rats in complementary tasks designed to alleviate this performance confound. Surprisingly, dS lesions spared task-specific procedural memories but altered the kinematics of their expression in motor routines. Further behavioral analyses combined with simulations in the optimal control framework indicated that these alterations reflected an increased sensitivity to effort with preserved reward-seeking and ability to modulate movement speed. By setting the sensitivity to effort, the dS contributes to the optimization of the energy invested into voluntary movements. Such an elementary function of the dS might explain its implication in both procedural decisions and the control of movement speed.

neuroscience↗

bioRxiv2019

The Embodied Nature of Well-Timed Behavior

How animals adapt their movements to take advantage of behaviorally-relevant time intervals is not well understood, especially in the supra-second timescale. It has been proposed that motor timing depends on the emergence of self-sustained dynamics across ensembles of neurons. Alternatively, evidence from operant conditioning suggests that animals can develop motor routines to adapt their behavior to fixed temporal constraints. But it is unclear whether animals can accurately time their behavior without the help of motor routines. To address this issue, we used a task in which rats, freely moving on a motorized treadmill, could obtain a reward if they approached it after a fixed interval. Most animals took advantage of the treadmill length and its moving direction to develop, by trial-and-error, a unique motor routine whose execution resulted in the precise timing of their reward approaches. Noticeably, when proficient animals occasionally failed to follow this routine, the timing of their reward approaches was systematically poor. In a second step, we trained naive animals in modified versions of the task specifically designed to prevent the development of this motor strategy. Compared to rats trained in the first protocol, these animals never reached a comparable level of timing accuracy. We conclude that motor timing critically depends on the ability of animals to develop motor routines adapted to the structure of their environment. Our work also suggests that self-sustained neuronal activity alone may not be sufficient to support motor timing, at least in the supra-second timescale.

animal behavior and cognition↗