Automated identification of honey bee pollen loads for field-applied palynological studies.

In a changing world, it is crucial to characterise communities and their evolution over time. Because social insect pollinators forage on flowering plants around the colony, the nest potentially contains important information about the pollinated plants such as species identity and plant phenology. In this paper, we introduce new approaches to assess plant composition in a Mediterranean summer plant community from pollen foraged by honeybees.

Unravelling impacts of the insecticide deltamethrin on neuronal sodium channels in honey bees: Molecular insights and behavioural outcomes.

The current risk assessment framework for insecticides suffers from certain shortcomings in adequately addressing the effects of low doses on off-target species. To remedy this gap, a combination of behavioural assays and in vitro cellular approaches are required to refine the precision of toxicity assessment. The domestic honey bee has long been standing as an emblematic pollinator in ecotoxicology, and once more, it provides us with a practical testing model for this purpose.

Honeybee CaV4 has distinct permeation, inactivation, and pharmacology from homologous NaV channels.

DSC1, a Drosophila channel with sequence similarity to the voltage-gated sodium channel (NaV), was identified over 20 years ago. This channel was suspected to function as a non-specific cation channel with the ability to facilitate the permeation of calcium ions (Ca2+). A honeybee channel homologous to DSC1 was recently cloned and shown to exhibit strict selectivity for Ca2+, while excluding sodium ions (Na+), thus defining a new family of Ca2+ channels, known as CaV4.

Functional Characterization of Four Known Cav2.1 Variants Associated with Neurodevelopmental Disorders.

Cav2.1 channels are expressed throughout the brain and are the predominant Ca channels in the Purkinje cells. These cerebellar neurons fire spontaneously, and Cav2.

Mammalian Brain Ca Channel Activity Transplanted into Oocytes.

Several mutations on neuronal voltage-gated Ca channels (VGCC) have been shown to cause neurological disorders and contribute to the initiation of epileptic seizures, migraines, or cerebellar degeneration. Analysis of the functional consequences of these mutations mainly uses heterologously expressed mutated channels or transgenic mice which mimic these pathologies, since direct electrophysiological approaches on brain samples are not easily feasible. We demonstrate that mammalian voltage-gated Ca channels from membrane preparation can be microtransplanted into oocytes and can conserve their activity.

Different efficiency of auxiliary/chaperone proteins to promote the functional reconstitution of honeybee glutamate and acetylcholine receptors in Xenopus laevis oocytes.

Heterologous expression systems (e.g., Xenopus laevis oocytes) are useful to study the biophysical properties and pharmacology of ionotropic receptors such as ionotropic glutamate (iGLuRs) and nicotinic acetylcholine (nAChRs) receptors.

The Glutathione Metabolite γ-Glutamyl-Glutamate Partially Activates Glutamate NMDA Receptors in Central Neurons With Higher Efficacy for GluN2B-Containing Receptors.

Gamma-L-glutamyl-L-glutamate (γ-Glu-Glu) was synthetized and further characterized for its activity on cultured neurons. We observed that γ-Glu-Glu elicited excitatory effects on neurons likely by activating mainly the N-methyl-D-aspartate (NMDA) receptors. These effects were dependent on the integrity of synaptic transmission as they were blocked by tetrodotoxin (TTX).

Manipulations of Glutathione Metabolism Modulate IP-Mediated Store-Operated Ca Entry on Astroglioma Cell Line.

The regulation of the redox status involves the activation of intracellular pathways as Nrf2 which provides hormetic adaptations against oxidative stress in response to environmental stimuli. In the brain, Nrf2 activation upregulates the formation of glutathione (GSH) which is the primary antioxidant system mainly produced by astrocytes. Astrocytes have also been shown to be themselves the target of oxidative stress.

Heterogeneous expression of GABA receptor-like subunits LCCH3 and GRD reveals functional diversity of GABA receptors in the honeybee Apis mellifera.

Background And Purpose: Despite a growing awareness, annual losses of honeybee colonies worldwide continue to reach threatening levels for food safety and global biodiversity. Among the biotic and abiotic stresses probably responsible for these losses, pesticides, including those targeting ionotropic GABA receptors, are one of the major drivers. Most insect genomes include the ionotropic GABA receptor subunit gene, Rdl, and two GABA-like receptor subunit genes, Lcch3 and Grd.

Cav2.1 C-terminal fragments produced in Xenopus laevis oocytes do not modify the channel expression and functional properties.

The sequence and genomic organization of the CACNA1A gene that encodes the Cav2.1 subunit of both P and Q-type Ca channels are well conserved in mammals. In human, rat and mouse CACNA1A, the use of an alternative acceptor site at the exon 46-47 boundary results in the expression of a long Cav2.

Targeting TMEM176B Enhances Antitumor Immunity and Augments the Efficacy of Immune Checkpoint Blockers by Unleashing Inflammasome Activation.

Although immune checkpoint blockers have yielded significant clinical benefits in patients with different malignancies, the efficacy of these therapies is still limited. Here, we show that disruption of transmembrane protein 176B (TMEM176B) contributes to CD8 T cell-mediated tumor growth inhibition by unleashing inflammasome activation. Lack of Tmem176b enhances the antitumor activity of anti-CTLA-4 antibodies through mechanisms involving caspase-1/IL-1β activation.

Assessment of Dural Ectasia Using Computed Tomodensitometry as a Criterion in Marfan Syndrome.

Objective: The aim of this study was to reevaluate dural ectasia criteria in Marfan syndrome patients fulfilling the revised Ghent criteria.

Methods: Lumbar computed tomography scans of 19 Marfan patients and 30 matched control subjects were retrospectively assessed. Dural sac ratio (DSR), nerve root sleeve diameter, pedicle width, and a scalloping or meningocele presence were each assessed by 2 readers blinded from the diagnosis.

Multiple combinations of RDL subunits diversify the repertoire of GABA receptors in the honey bee parasite .

In insects, γ-aminobutyric acid (GABA) is the major inhibitory neurotransmitter, and GABA-gated ion channels are the target of different classes of insecticides, including fipronil. We report here the cloning of six subunits (four RDL, one LCCH3, and one GRD) that constitute the repertoire of the GABA-gated ion channel family of the mite (), a honey bee ectoparasite. We also isolated a truncated GRD subunit with a premature stop codon.

Characterization of l-Theanine Excitatory Actions on Hippocampal Neurons: Toward the Generation of Novel N-Methyl-d-aspartate Receptor Modulators Based on Its Backbone.

l-Theanine (or l-γ-N-ethyl-glutamine) is the major amino acid found in Camellia sinensis. It has received much attention because of its pleiotropic physiological and pharmacological activities leading to health benefits in humans, especially. We describe here a new, easy, efficient, and environmentally friendly chemical synthesis of l-theanine and l-γ-N-propyl-Gln and their corresponding d-isomers.

Biophysical characterization of the honeybee DSC1 orthologue reveals a novel voltage-dependent Ca2+ channel subfamily: CaV4.

Bilaterian voltage-gated Na(+) channels (NaV) evolved from voltage-gated Ca(2+) channels (CaV). The Drosophila melanogaster Na(+) channel 1 (DSC1), which features a D-E-E-A selectivity filter sequence that is intermediate between CaV and NaV channels, is evidence of this evolution. Phylogenetic analysis has classified DSC1 as a Ca(2+)-permeable Na(+) channel belonging to the NaV2 family because of its sequence similarity with NaV channels.

Absence of γ-aminobutyric acid-a receptor potentiation in central hypersomnolence disorders.

Objective: The pathophysiology of idiopathic hypersomnia (IH) remains unclear. Recently, cerebrospinal fluid (CSF)-induced enhancement of γ-aminobutyric acid (GABA)-A receptor activity was found in patients with IH compared to controls.

Methods: Fifteen unrelated patients (2 males and 13 females) affected with typical IH, 12 patients (9 males and 3 females) with narcolepsy type 1, and 15 controls (9 males and 6 females) with unspecified hypersomnolence (n = 7) and miscellaneous neurological conditions (n = 8) were included.

Multiple sclerosis lesion formation and early evolution revisited: A weekly high-resolution magnetic resonance imaging study.

Background: Several magnetic resonance imaging (MRI) studies investigated the evolution of multiple sclerosis (MS) lesions to understand the pathophysiological mechanisms leading to blood-brain barrier breakdown and lesion formation. Only a few assessed the early natural history of MS lesions using short-interval longitudinal MRI.

Objective: The purpose of this study was to characterize MS lesion occurrence and early evolution on high-resolution MRI acquired at weekly intervals.

Characterization of the honeybee AmNaV1 channel and tools to assess the toxicity of insecticides.

Pollination is important for both agriculture and biodiversity. For a significant number of plants, this process is highly, and sometimes exclusively, dependent on the pollination activity of honeybees. The large numbers of honeybee colony losses reported in recent years have been attributed to colony collapse disorder.

Regulation of neuronal high-voltage activated Ca(V)2 Ca(2+) channels by the small GTPase RhoA.

High-Voltage-Activated (HVA) Ca(2+) channels are known regulators of synapse formation and transmission and play fundamental roles in neuronal pathophysiology. Small GTPases of Rho and RGK families, via their action on both cytoskeleton and Ca(2+) channels are key molecules for these processes. While the effects of RGK GTPases on neuronal HVA Ca(2+) channels have been widely studied, the effects of RhoA on the HVA channels remains however elusive.

Molecular characterization and functional expression of the Apis mellifera voltage-dependent Ca2+ channels.

Voltage-gated Ca(2+) channels allow the influx of Ca(2+) ions from the extracellular space upon membrane depolarization and thus serve as a transducer between membrane potential and cellular events initiated by Ca(2+) transients. Most insects are predicted to possess three genes encoding Cavα, the main subunit of Ca(2+) channels, and several genes encoding the two auxiliary subunits, Cavβ and Cavα2δ; however very few of these genes have been cloned so far. Here, we cloned three full-length cDNAs encoding the three Cavα subunits (AmelCav1a, AmelCav2a and AmelCav3a), a cDNA encoding a novel variant of the Cavβ subunit (AmelCavβc), and three full-length cDNAs encoding three Cavα2δ subunits (AmelCavα2δ1 to 3) of the honeybee Apis mellifera.

Pyrethroids differentially alter voltage-gated sodium channels from the honeybee central olfactory neurons.

The sensitivity of neurons from the honey bee olfactory system to pyrethroid insecticides was studied using the patch-clamp technique on central 'antennal lobe neurons' (ALNs) in cell culture. In these neurons, the voltage-dependent sodium currents are characterized by negative potential for activation, fast kinetics of activation and inactivation, and the presence of cumulative inactivation during train of depolarizations. Perfusion of pyrethroids on these ALN neurons submitted to repetitive stimulations induced (1) an acceleration of cumulative inactivation, and (2) a marked slowing of the tail current recorded upon repolarization.

Characterization of the first honeybee Ca²⁺ channel subunit reveals two novel species- and splicing-specific modes of regulation of channel inactivation.

The honeybee is a model system to study learning and memory, and Ca(2+) signals play a key role in these processes. We have cloned, expressed, and characterized the first honeybee Ca(2+) channel subunit. We identified two splice variants of the Apis CaVβ Ca(2+) channel subunit (Am-CaVβ) and demonstrated expression in muscle and neurons.

Cacnb4 directly couples electrical activity to gene expression, a process defective in juvenile epilepsy.

Calcium current through voltage-gated calcium channels (VGCC) controls gene expression. Here, we describe a novel signalling pathway in which the VGCC Cacnb4 subunit directly couples neuronal excitability to transcription. Electrical activity induces Cacnb4 association to Ppp2r5d, a regulatory subunit of PP2A phosphatase, followed by (i) nuclear translocation of Cacnb4/Ppp2r5d/PP2A, (ii) association with the tyrosine hydroxylase (TH) gene promoter through the nuclear transcription factor thyroid hormone receptor alpha (TRα), and (iii) histone binding through association of Cacnb4 with HP1γ concomitantly with Ser(10) histone H3 dephosphorylation by PP2A.

Two sets of amino acids of the domain I of Cav2.3 Ca(2+) channels contribute to their high sensitivity to extracellular protons.

Extracellular acidification decreases Ca(2+) current amplitude and produces a depolarizing shift in the activation potential (Va) of voltage-gated Ca(2+) channels (VGCC). These effects are common to all VGCC, but differences exist between Ca(2+) channel types and the underlying molecular mechanisms remain largely unknown. We report here that the changes in current amplitude induced by extracellular acidification or alkalinisation are more important for Cav2.