Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 126
Filter
1.
Neural Regen Res ; 20(3): 660-670, 2025 Mar 01.
Article in English | MEDLINE | ID: mdl-38886932

ABSTRACT

Spinal cord injury results in paralysis, sensory disturbances, sphincter dysfunction, and multiple systemic secondary conditions, most arising from autonomic dysregulation. All this produces profound negative psychosocial implications for affected people, their families, and their communities; the financial costs can be challenging for their families and health institutions. Treatments aimed at restoring the spinal cord after spinal cord injury, which have been tested in animal models or clinical trials, generally seek to counteract one or more of the secondary mechanisms of injury to limit the extent of the initial damage. Most published works on structural/functional restoration in acute and chronic spinal cord injury stages use a single type of treatment: a drug or trophic factor, transplant of a cell type, and implantation of a biomaterial. Despite the significant benefits reported in animal models, when translating these successful therapeutic strategies to humans, the result in clinical trials has been considered of little relevance because the improvement, when present, is usually insufficient. Until now, most studies designed to promote neuroprotection or regeneration at different stages after spinal cord injury have used single treatments. Considering the occurrence of various secondary mechanisms of injury in the acute and sub-acute phases of spinal cord injury, it is reasonable to speculate that more than one therapeutic agent could be required to promote structural and functional restoration of the damaged spinal cord. Treatments that combine several therapeutic agents, targeting different mechanisms of injury, which, when used as a single therapy, have shown some benefits, allow us to assume that they will have synergistic beneficial effects. Thus, this narrative review article aims to summarize current trends in the use of strategies that combine therapeutic agents administered simultaneously or sequentially, seeking structural and functional restoration of the injured spinal cord.

2.
Int J Mol Sci ; 25(17)2024 Aug 23.
Article in English | MEDLINE | ID: mdl-39273121

ABSTRACT

Traumatic spinal cord injury (tSCI) has complex pathophysiological events that begin after the initial trauma. One such event is fibroglial scar formation by fibroblasts and reactive astrocytes. A strong inhibition of axonal growth is caused by the activated astroglial cells as a component of fibroglial scarring through the production of inhibitory molecules, such as chondroitin sulfate proteoglycans or myelin-associated proteins. Here, we used neural precursor cells (aldynoglia) as promoters of axonal growth and a fibrin hydrogel gelled under alkaline conditions to support and guide neuronal cell growth, respectively. We added Tol-51 sulfoglycolipid as a synthetic inhibitor of astrocyte and microglia in order to test its effect on the axonal growth-promoting function of aldynoglia precursor cells. We obtained an increase in GFAP expression corresponding to the expected glial phenotype for aldynoglia cells cultured in alkaline fibrin. In co-cultures of dorsal root ganglia (DRG) and aldynoglia, the axonal growth promotion of DRG neurons by aldynoglia was not affected. We observed that the neural precursor cells first clustered together and then formed niches from which aldynoglia cells grew and connected to groups of adjacent cells. We conclude that the combination of alkaline fibrin with synthetic sulfoglycolipid Tol-51 increased cell adhesion, cell migration, fasciculation, and axonal growth capacity, promoted by aldynoglia cells. There was no negative effect on the behavior of aldynoglia cells after the addition of sulfoglycolipid Tol-51, suggesting that a combination of aldynoglia plus alkaline fibrin and Tol-51 compound could be useful as a therapeutic strategy for tSCI repair.


Subject(s)
Axons , Fibrin , Ganglia, Spinal , Animals , Ganglia, Spinal/drug effects , Ganglia, Spinal/metabolism , Ganglia, Spinal/cytology , Axons/metabolism , Axons/drug effects , Fibrin/metabolism , Hydrogels/chemistry , Hydrogels/pharmacology , Rats , Glycolipids/pharmacology , Neural Stem Cells/drug effects , Neural Stem Cells/metabolism , Neural Stem Cells/cytology , Neurons/metabolism , Neurons/drug effects , Cells, Cultured , Coculture Techniques , Spinal Cord Injuries/metabolism , Spinal Cord Injuries/drug therapy , Spinal Cord Injuries/pathology , Neuroglia/drug effects , Neuroglia/metabolism , Astrocytes/drug effects , Astrocytes/metabolism , Spinal Cord/metabolism , Spinal Cord/drug effects , Spinal Cord/cytology , Cell Movement/drug effects
4.
Cells ; 13(16)2024 Aug 08.
Article in English | MEDLINE | ID: mdl-39195214

ABSTRACT

Following spinal cord injury (SCI), the regenerative capacity of the central nervous system (CNS) is severely limited by the failure of axonal regeneration. The regeneration of CNS axons has been shown to occur by grafting predegenerated peripheral nerves (PPNs) and to be promoted by the transplantation of neural precursor cells (NPCs). The introduction of a combinatorial treatment of PPNs and NPCs after SCI has to address the additional problem of glial scar formation, which prevents regenerating axons from leaving the implant and making functional connections. Previously, we discovered that the synthetic sulfoglycolipid Tol-51 inhibits astrogliosis. The objective was to evaluate axonal regeneration and locomotor function improvement after SCI in rats treated with a combination of PPN, NPC, and Tol-51. One month after SCI, the scar tissue was removed and replaced with segments of PPN or PPN+Tol-51; PPN+NPC+Tol-51. The transplantation of a PPN segment favors regenerative axonal growth; in combination with Tol-51 and NPC, 30% of the labeled descending corticospinal axons were able to grow through the PPN and penetrate the caudal spinal cord. The animals treated with PPN showed significantly better motor function. Our data demonstrate that PPN implants plus NPC and Tol-51 allow successful axonal regeneration in the CNS.


Subject(s)
Nerve Regeneration , Neural Stem Cells , Peripheral Nerves , Spinal Cord Injuries , Animals , Spinal Cord Injuries/physiopathology , Spinal Cord Injuries/therapy , Spinal Cord Injuries/pathology , Rats , Nerve Regeneration/drug effects , Neural Stem Cells/drug effects , Neural Stem Cells/transplantation , Neural Stem Cells/cytology , Peripheral Nerves/drug effects , Peripheral Nerves/pathology , Female , Axons/drug effects , Glycolipids/pharmacology , Recovery of Function/drug effects
5.
Pharmaceutics ; 16(8)2024 Aug 02.
Article in English | MEDLINE | ID: mdl-39204381

ABSTRACT

Cancer and bacterial infections rank among the most significant global health threats. accounting for roughly 25 million fatalities each year. This statistic underscores the urgent necessity for developing novel drugs, enhancing current treatments, and implementing systems that boost their bioavailability to achieve superior therapeutic outcomes. Liposomes have been recognised as effective carriers; nonetheless, they encounter issues with long-term stability and structural integrity, which limit their pharmaceutical applicability. Chitosomes (chitosan-coated liposomes) are generally a good alternative to solve these issues. This research aims to demonstrate the effective individual encapsulation of ciprofloxacin (antibacterial, hydrophilic) and etoposide (anticancer, hydrophobic), within chitosomes to create more effective drug delivery systems (oral administration for ciprofloxacin, parenteral administration for etoposide). Thus, liposomes and chitosomes were prepared using the thin-film hydration technique and were characterised through ATR-FTIR, Dynamic Light Scattering (DLS), zeta potential, and release profiling. In both cases, the application of chitosomes enhanced long-term stability in size and surface charge. Chitosome-encapsulated ciprofloxacin formulations exhibited a slower and sustained release profile, while the combined effect of etoposide and chitosan showed heightened efficacy against the glioblastoma cell line U373. Therefore, coating liposomes with chitosan improved the encapsulation system's properties, resulting in a promising method for drug delivery.

6.
Toxins (Basel) ; 16(7)2024 Jul 16.
Article in English | MEDLINE | ID: mdl-39057960

ABSTRACT

Hyperhidrosis (HH) is defined as the production of more sweat than is necessary for its thermoregulatory function, negatively affecting patients' quality of life and interfering with their social, work and family life. In this context, the aim of thisstudy was to evaluate the efficacy of two different doses of botulinum toxin type A (50 or 100 units) in each axilla in severe primary axillary hyperhidrosis. A descriptive, observational, cross-sectional and post-authorisation study was conducted onpatients referred to our department.Thirty-one patients with severe primary axillary hyperhidrosis were included, some of whom received more than one infiltration during the follow-up period, performing a total of 82 procedures. They were assigned by simple random sampling to two types of treatment: infiltration of 50 or 100 units (U) of botulinum toxin A per axilla.Hyperhidrosis severity was assessed using the Hyperhidrosis Disease Severity Scale (HDSS), and quality of life was assessed using the Dermatology Life Quality Index (DLQI) questionnaire. Onabotulinum toxin A infiltration reduced the severity of hyperhidrosis and improved the quality of life of the treated patients, with no significant differences between the two groups.


Subject(s)
Axilla , Botulinum Toxins, Type A , Hyperhidrosis , Quality of Life , Humans , Hyperhidrosis/drug therapy , Botulinum Toxins, Type A/administration & dosage , Botulinum Toxins, Type A/therapeutic use , Female , Adult , Male , Cross-Sectional Studies , Young Adult , Treatment Outcome , Middle Aged
7.
Cell Rep Med ; 5(4): 101483, 2024 Apr 16.
Article in English | MEDLINE | ID: mdl-38579727

ABSTRACT

Immune cell phenotyping frequently detects lineage-unrelated receptors. Here, we report that surface receptors can be transferred from primary macrophages to CD4 T cells and identify the Fcγ receptor CD32 as driver and cargo of this trogocytotic transfer. Filamentous CD32+ nanoprotrusions deposit distinct plasma membrane patches onto target T cells. Transferred receptors confer cell migration and adhesion properties, and macrophage-derived membrane patches render resting CD4 T cells susceptible to infection by serving as hotspots for HIV-1 binding. Antibodies that recognize T cell epitopes enhance CD32-mediated trogocytosis. Such autoreactive anti-HIV-1 envelope antibodies can be found in the blood of HIV-1 patients and, consistently, the percentage of CD32+ CD4 T cells is increased in their blood. This CD32-mediated, antigen-independent cell communication mode transiently expands the receptor repertoire and functionality of immune cells. HIV-1 hijacks this mechanism by triggering the generation of trogocytosis-promoting autoantibodies to gain access to immune cells critical to its persistence.


Subject(s)
HIV Infections , HIV Seropositivity , HIV-1 , Humans , CD4-Positive T-Lymphocytes , Receptors, IgG/metabolism , Autoantibodies/metabolism , Trogocytosis
8.
Polymers (Basel) ; 16(8)2024 Apr 10.
Article in English | MEDLINE | ID: mdl-38674956

ABSTRACT

Several composites based on poly(3-hydroxybutyrate) (PHB) and mesoporous SBA-15 silica were prepared by solvent-casting followed by a further stage of compression molding. The thermal stability, phase transitions and crystalline details of these composites were studied, paying special attention to the confinement of the PHB polymeric chains into the mesopores of the silica. For that, differential scanning calorimetry (DSC) and real-time variable-temperature X-ray scattering at small angles (SAXS) were performed. Confinement was stated first by the existence of a small endotherm at temperatures around 20 °C below the main melting or crystallization peak, being later confirmed by a notable discontinuity in the intensity of the main (100) diffraction from the mesoporous silica observed through SAXS experiments, which is related to the change in the scattering contrast before and after the crystallization or melting of the polymer chains. Furthermore, the usual α modification of PHB was developed in all samples. Finally, a preliminary investigation of mechanical and relaxation parameters was carried out through dynamic-mechanical thermal analysis (DMTA). The results show, in the temperature interval analyzed, two relaxations, named α and ß (the latest related to the glass transition) in order of decreasing temperatures, in all specimens. The role of silica as a filler is mainly observed at temperatures higher than the glass transition. In such cases, stiffness is dependent on SBA-15 content.

9.
Cell Rep ; 43(3): 113941, 2024 Mar 26.
Article in English | MEDLINE | ID: mdl-38478523

ABSTRACT

Resting CD4 T cells resist productive HIV-1 infection. The HIV-2/simian immunodeficiency virus protein viral accessory protein X (Vpx) renders these cells permissive to infection, presumably by alleviating blocks at cytoplasmic reverse transcription and subsequent nuclear import of reverse-transcription/pre-integration complexes (RTC/PICs). Here, spatial analyses using quantitative virus imaging techniques reveal that HIV-1 capsids containing RTC/PICs are readily imported into the nucleus, recruit the host dependency factor CPSF6, and translocate to nuclear speckles in resting CD4 T cells. Reverse transcription, however, remains incomplete, impeding proviral integration and viral gene expression. Vpx or pharmacological inhibition of the deoxynucleotide triphosphohydrolase (dNTPase) activity of the restriction factor SAM domain and HD domain-containing protein 1 (SAMHD1) increases levels of nuclear reverse-transcribed cDNA and facilitates HIV-1 integration. Nuclear import and intranuclear transport of viral complexes therefore do not pose important blocks to HIV-1 in resting CD4 T cells, and the limitation to reverse transcription by SAMHD1's dNTPase activity constitutes the main pre-integration block to infection.


Subject(s)
HIV Infections , HIV Seropositivity , HIV-1 , Monomeric GTP-Binding Proteins , Animals , Humans , HIV-1/genetics , CD4-Positive T-Lymphocytes/metabolism , SAM Domain and HD Domain-Containing Protein 1/metabolism , HIV-2/genetics , Viral Regulatory and Accessory Proteins/metabolism , Monomeric GTP-Binding Proteins/metabolism , HEK293 Cells
10.
Am J Phys Med Rehabil ; 103(3): 245-250, 2024 Mar 01.
Article in English | MEDLINE | ID: mdl-37602548

ABSTRACT

PURPOSE: The aim of the study is to evaluate the predictive factors for a poor prognosis in patients with facial paralysis evaluated in the rehabilitation department of a tertiary hospital. METHODS: We have conducted a prospective cohort study. Patients who required elective botulinum toxin infiltration, surgical treatment, or follow-up appointments longer than 6 months due to incomplete recovery were considered to have a poor prognosis. Descriptive and analytical analyses of clinical and epidemiological variables were performed. The follow-up period was 6 mos. RESULTS: A total of 47 adult patients were analyzed, 54.2% of whom were women. The mean age was 53.2 yrs (SD, 15.5 yrs). Twenty-five percent had an unfavorable prognosis. A statistically significant association with prognosis was observed for neurophysiological results and the scores of the House-Brackmann scale and the Sunnybrook Facial Grading System. CONCLUSIONS: Neurophysiological tests are especially useful when evaluating prognosis. Likewise, Sunnybrook Facial Grading System is a useful and accessible tool with prognostic value, especially within a month of initial diagnosis, when a score lower than 65 indicates a poor prognosis with high sensitivity and specificity. These tools can be especially useful to reduce the clinical and psychological impact and to provide patients with early therapeutic management.


Subject(s)
Facial Paralysis , Adult , Humans , Female , Middle Aged , Male , Facial Paralysis/etiology , Facial Paralysis/surgery , Prospective Studies , Prognosis
11.
Arch Med Res ; 55(1): 102935, 2024 01.
Article in English | MEDLINE | ID: mdl-38157747

ABSTRACT

Traumatic spinal cord injury (SCI) results in partial or complete motor deficits, such as paraplegia, tetraplegia, and sphincter control, as well as sensory disturbances and autonomic dysregulation such as arterial hypotension, lack of sweating, and alterations in skin lability. All this has a strong psychological impact on the affected person and his/her family, as well as costs to healthcare institutions with an economic burden in the short, medium, and long terms. Despite at least forty years of experimental animal studies and several clinical trials with different therapeutic strategies, effective therapy is not universally accepted. Most of the published works on acute and chronic injury use a single treatment, such as medication, trophic factor, transplant of a cell type, and so on, to block some secondary injury mechanisms or promote some mechanisms of structural/functional restoration. However, despite significant results in experimental models, the outcome is a moderate improvement in muscle strength, sensation, or eventually in sphincter control, which has been considered non-significant in human clinical trials. Here we present a brief compilation of successful individual treatments that have been applied to secondary mechanisms of action. These studies show limited neuroprotective or neurorestorative approaches in animal models and clinical trials. Thus, the few benefits achieved so far represent a rationale to further explore other strategies that seek better structural and functional restoration of the injured spinal cord.


Subject(s)
Spinal Cord Injuries , Humans , Animals , Female , Male , Spinal Cord Injuries/therapy , Quadriplegia
12.
Int J Mol Sci ; 24(18)2023 Sep 11.
Article in English | MEDLINE | ID: mdl-37762251

ABSTRACT

Spinal cord injury is a traumatic lesion that causes a catastrophic condition in patients, resulting in neuronal deficit and loss of motor and sensory function. That loss is caused by secondary injury events following mechanical damage, which results in cell death. One of the most important events is inflammation, which activates molecules like proinflammatory cytokines (IL-1ß, IFN-γ, and TNF-α) that provoke a toxic environment, inhibiting axonal growth and exacerbating CNS damage. As there is no effective treatment, one of the developed therapies is neuroprotection of the tissue to preserve healthy tissue. Among the strategies that have been developed are the use of cell therapy, the use of peptides, and molecules or supplements that have been shown to favor an anti-inflammatory environment that helps to preserve tissue and cells at the site of injury, thus favoring axonal growth and improved locomotor function. In this review, we will explain some of these strategies used in different animal models of spinal cord injury, their activity as modulators of the immune system, and the benefits they have shown.


Subject(s)
Spinal Cord Injuries , Animals , Humans , Spinal Cord Injuries/drug therapy , Inflammation/pathology , Neurons/metabolism , Anti-Inflammatory Agents/therapeutic use , Cytokines/metabolism , Spinal Cord/metabolism , Recovery of Function/physiology
13.
Nat Commun ; 14(1): 4990, 2023 08 17.
Article in English | MEDLINE | ID: mdl-37591878

ABSTRACT

The role, magnitude, and molecular nature of trans-driven expression variation underlying the upregulation of detoxification genes in pesticide resistant arthropod populations has remained enigmatic. In this study, we performed expression quantitative trait locus (eQTL) mapping (n = 458) between a pesticide resistant and a susceptible strain of the generalist herbivore and crop pest Tetranychus urticae. We found that a single trans eQTL hotspot controlled large differences in the expression of a subset of genes in different detoxification gene families, as well as other genes associated with host plant use. As established by additional genetic approaches including RNAi gene knockdown, a duplicated gene with a nuclear hormone receptor HR96-related ligand-binding domain was identified as causal for the expression differences between strains. The presence of a large family of HR96-related genes in T. urticae may enable modular control of detoxification and host plant use genes, facilitating this species' known and rapid evolution to diverse pesticides and host plants.


Subject(s)
Arthropods , Pesticides , Animals , Herbivory , Quantitative Trait Loci/genetics , Gene Expression
14.
Proc Mach Learn Res ; 202: 34831-34854, 2023 Jul.
Article in English | MEDLINE | ID: mdl-37575467

ABSTRACT

We propose causal isotonic calibration, a novel nonparametric method for calibrating predictors of heterogeneous treatment effects. In addition, we introduce a novel data-efficient variant of calibration that avoids the need for hold-out calibration sets, which we refer to as cross-calibration. Causal isotonic cross-calibration takes cross-fitted predictors and outputs a single calibrated predictor obtained using all available data. We establish under weak conditions that causal isotonic calibration and cross-calibration both achieve fast doubly-robust calibration rates so long as either the propensity score or outcome regression is estimated well in an appropriate sense. The proposed causal isotonic calibrator can be wrapped around any black-box learning algorithm to provide strong distribution-free calibration guarantees while preserving predictive performance.

15.
Molecules ; 28(11)2023 May 23.
Article in English | MEDLINE | ID: mdl-37298738

ABSTRACT

In this study, nanocomposites based on polypropylene are synthesized by the in situ polymerization of propene in the presence of mesoporous SBA-15 silica, which acts as a carrier of the catalytic system (zirconocene as catalyst and methylaluminoxane as cocatalyst). The protocol for the immobilization and attainment of hybrid SBA-15 particles involves a pre-stage of contact between the catalyst with cocatalyst before their final functionalization. Two zirconocene catalysts are tested in order to attain materials with different microstructural characteristics, molar masses and regioregularities of chains. Some polypropylene chains are able to be accommodated within the silica mesostructure of these composites. Thus, an endothermic event of small intensity appears during heating calorimetric experiments at approximately 105 °C. The existence of these polypropylene crystals, confined within the nanometric channels of silica, is corroborated by SAXS measurements obtained via the change in the intensity and position of the first-order diffraction of SBA-15. The incorporation of silica also has a very significant effect on the rheological response of the resultant materials, leading to important variations in various magnitudes, such as the shear storage modulus, viscosity and δ angle, when a comparison is established with the corresponding neat iPP matrices. Rheological percolation is reached, thus demonstrating the role of SBA-15 particles as filler, in addition to the supporting role that they exert during the polymerizations.


Subject(s)
Nanocomposites , Polypropylenes , Polymerization , Polypropylenes/chemistry , Metallocenes , Molecular Weight , Scattering, Small Angle , X-Ray Diffraction , Nanocomposites/chemistry , Silicon Dioxide/chemistry
16.
J Oncol Pharm Pract ; 29(6): 1525-1528, 2023 Sep.
Article in English | MEDLINE | ID: mdl-37254508

ABSTRACT

INTRODUCTION: Pembrolizumab is an immune checkpoint inhibitor that promotes effector T-cell functions on malignant cells by binding to programmed cell death protein 1 (PD-1). Pembrolizumab is well tolerated in most cases with an adverse event profile consisting mainly of pruritus, fatigue, and anorexia. Cardiotoxicity comprises 1% of the total adverse events. CASE REPORT: We present a case of a 64-year-old female with non-small cell lung cancer (NSCLC) who developed pleuropericarditis following pembrolizumab therapy. MANAGEMENT & OUTCOME: The patient was successfully managed with colchicine, furosemide, and timely initiation of methylprednisolone with the improvement of her symptoms. The decision to discontinue pembrolizumab was made, and six months after this intervention, the patient has remained asymptomatic. DISCUSSION: Clinicians should recognize these potential immune-mediated adverse effects to provide effective and timely management and optimize patient care.


Subject(s)
Carcinoma, Non-Small-Cell Lung , Drug-Related Side Effects and Adverse Reactions , Lung Neoplasms , Female , Humans , Middle Aged , Carcinoma, Non-Small-Cell Lung/therapy , Cardiotoxicity , Drug-Related Side Effects and Adverse Reactions/drug therapy , Immune Checkpoint Inhibitors/adverse effects , Lung Neoplasms/diagnosis
17.
Polymers (Basel) ; 15(9)2023 Apr 27.
Article in English | MEDLINE | ID: mdl-37177226

ABSTRACT

Composites based on an L-rich poly(lactic acid) (PLLA) and MCM-41, either neat or modified with a silver (MCM-41@Ag), are achieved by solvent casting, being next processed by compression molding. Ag is mainly embedded as nanowires within the hybrid MCM-41@Ag particles, enabling its antimicrobial character. In these composites, the PLLA thermal stability, nucleation efficiency, and mechanical response are dependent on the MCM-41 nature and, to a lesser extent, on its content. Thus, differences in transitions of the PLLA matrix are noticed during cooling at 10 °C/min and in the subsequent heating when composites with neat or modified MCM-41 are compared. A very remarkable nucleation effect is played by pristine MCM-41, being inferior when MCM-41@Ag is incorporated into the PLLA. Wide angle X-ray scattering (WAXS) measurements using synchrotron radiation and performed under variable-temperature conditions in the composites containing MCM-41@Ag indicate that during cold crystallization, the disordered α' polymorph is initially formed, but it rapidly transforms into ordered α crystals. A long spacing peak, clearly seen in pure PLLA, appears as a small shoulder in PLLAMCM@Ag4 and is undetectable in PLLAMCM@Ag9 and PLLAMCM@Ag20. Furthermore, an increase in MH with the silica content is found in the two sets of composites, the higher MH values being observed in the family of PLLA and MCM-41@Ag. Finally, remarkable antimicrobial features are noticeable in the composites with MCM-41@Ag since this modified silica transfers its biocidal characteristics into the PLLA composites.

18.
Evol Appl ; 16(4): 863-879, 2023 Apr.
Article in English | MEDLINE | ID: mdl-37124092

ABSTRACT

Pesticide resistance relies on a myriad of mechanisms, ranging from single mutations to a complex and polygenic architecture, and it involves mechanisms such as target-site insensitivity, metabolic detoxification, or a combination of these, with either additive or synergistic effects. Several resistance mechanisms against abamectin, a macrocyclic lactone widely used in crop protection, have been reported in the cosmopolitan pest Tetranychus urticae. However, it has been shown that a single mechanism cannot account for the high levels of abamectin resistance found across different mite populations. Here, we used experimental evolution combined with bulked segregant analyses to map quantitative trait loci (QTL) associated with abamectin resistance in two genetically unrelated populations of T. urticae. In these two independent QTL mapping experiments, three and four QTLs were identified, of which three were shared between experiments. Shared QTLs contained genes encoding subunits of the glutamate-gated chloride channel (GluCl) and harboured previously reported mutations, including G314D in GluCl1 and G326E in GluCl3, but also novel resistance candidate loci, including DNA helicases and chemosensory receptors. Surprisingly, the fourth QTL, present only in only one of the experiments and thus unique for one resistant parental line, revealed a non-functional variant of GluCl2, suggesting gene knock-out as resistance mechanism. Our study uncovers the complex basis of abamectin resistance, and it highlights the intraspecific diversity of genetic mechanisms underlying resistance in a cosmopolitan pest.

19.
Mol Ecol ; 32(15): 4278-4297, 2023 08.
Article in English | MEDLINE | ID: mdl-37211626

ABSTRACT

Pesticide resistance represents a clear and trackable case of adaptive evolution with a strong societal impact. Understanding the factors associated with the evolution and spread of resistance is imperative to develop sustainable crop management strategies. The two-spotted spider mite Tetranychus urticae, a major crop pest with worldwide distribution and a polyphagous lifestyle, has evolved resistance to most classes of pesticides. Tetranychus urticae exists as either a green- or a red-coloured morph. However, the extent of genetic divergence and reproductive compatibility vary across populations of these colour morphs, complicating their taxonomic resolution at the species level. Here, we studied patterns of genetic differentiation and barriers to gene flow within and between morphs of T. urticae in order to understand the factors that influence the spread of resistance mutations across its populations. We derived multiple iso-female lines from Tetranychus populations collected from agricultural crops. We generated genomic and morphological data, characterized their bacterial communities and performed controlled crosses. Despite morphological similarities, we found large genomic differentiation between the morphs. This pattern was reflected in the incomplete, but strong postzygotic incompatibility in crosses between colour morphs, while crosses within morphs from different geographical locations were largely compatible. In addition, our results suggest recent/on-going gene flow between green-coloured T. urticae and T. turkestani. By screening the sequences of 10 resistance genes, we found evidence for multiple independent origins and for single evolutionary origins of target-site resistance mutations. Our results indicate that target-site mutations mostly evolve independently in populations on different geographical locations, and that these mutations can spread due to incomplete barriers to gene flow within and between populations.


Subject(s)
Pesticides , Tetranychidae , Female , Animals , Color , Genome , Mutation , Genomics , Tetranychidae/genetics
20.
Polymers (Basel) ; 15(6)2023 Mar 16.
Article in English | MEDLINE | ID: mdl-36987271

ABSTRACT

Different amounts of carbon nanotubes (CNT) have been incorporated in materials based on poly(vinylidene fluoride) (PVDF) by solvent blending followed by their further precipitation. Final processing was performed by compression molding. The morphological aspects and crystalline characteristics have been examined, additionally exploring in these nanocomposites the common routes described in the pristine PVDF to induce the ß polymorph. This polar ß phase has been found to be promoted by the simple inclusion of CNT. Therefore, coexistence of the α and ß lattices occurs for the analyzed materials. The real-time variable-temperature X-ray diffraction measurements with synchrotron radiation at a wide angle have undoubtedly allowed us to observe the presence of the two polymorphs and determine the melting temperature of both crystalline modifications. Furthermore, the CNT plays a nucleating role in the PVDF crystallization, and also acts as reinforcement, increasing the stiffness of the nanocomposites. Moreover, the mobility within the amorphous and crystalline PVDF regions is found to change with the CNT content. Finally, the presence of CNT leads to a very remarkable increase in the conductivity parameter, in such a way that the transition from insulator to electrical conductor is reached in these nanocomposites at a percolation threshold ranging from 1 to 2 wt.%, leading to the excellent value of conductivity of 0.05 S/cm in the material with the highest content in CNT (8 wt.%).

SELECTION OF CITATIONS
SEARCH DETAIL