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PloS One 2024Humans have approximately 400 different olfactory receptors (hORs) and recognize odorants through the repertoire of hOR responses. Although the cell surface expression...
Humans have approximately 400 different olfactory receptors (hORs) and recognize odorants through the repertoire of hOR responses. Although the cell surface expression of hORs is critical to evaluate their response, hORs are poorly expressed on the surface of heterologous cells. To address this problem, previous studies have focused on hOR transportation to the membrane. Nevertheless, the response pattern of hORs to odorants has yet to be successfully linked, and the response sensitivity still remains to be improved. In this study, we demonstrate that increasing the transcriptional level can result in a significant increase in cell surface and functional expression of hORs. We used the TAR-Tat system, which increases the transcription efficiency through positive feedback, and found that OR1A1, OR6N2, and OR51M1 exhibited robust expression. Moreover, this system induces enhanced hOR responses to odorants, thus defining four hORs as novel n-hexanal receptors and n-hexanal is an inverse agonist to one of them. Our results suggested that using the TAR-Tat system and increasing the transcriptional level of hORs can help understanding the relationship between hORs and odorants that were previously undetectable. This finding could facilitate the understanding of the sense of smell by decoding the repertoire of hOR responses.
Topics: Receptors, Odorant; Humans; Transcription, Genetic; Odorants; Aldehydes
PubMed: 38917199
DOI: 10.1371/journal.pone.0306029 -
BioRxiv : the Preprint Server For... Jun 2024Mice are able to navigate an odor plume with a complex spatiotemporal structure in the dark to find the source of odorants. We developed a protocol to monitor behavior...
UNLABELLED
Mice are able to navigate an odor plume with a complex spatiotemporal structure in the dark to find the source of odorants. We developed a protocol to monitor behavior and record Ca transients in dorsal CA1 stratum pyramidale neurons at the hippocampus (dCA1) in mice navigating an odor plume in a 50 cm x 50 cm x 25 cm odor arena. Ca transients were imaged by an epifluorescence miniscope focused through a GRIN lens on dCA1 neurons expressing the calcium sensor GCaMP6f in Thy1-GCaMP6f mice. We describe the behavioral protocol to train the mice to perform this odor plume navigation task in an automated odor arena. We provide the step-by-step procedure for the surgery for GRIN lens implantation and baseplate placement for imaging GCaMP6f in CA1. We provide information on real time tracking of the mouse position to automate the start of the trials and delivery of a sugar water reward. In addition, we provide information on the use of an Intan board to synchronize metadata describing the automation of the odor navigation task and frame times for the miniscope and a FLIR camera tracking mouse position. Moreover, we delineate the pipeline used to process GCaMP6f fluorescence movies by motion correction using NorMCorre followed by identification of regions of interest (ROIs) with EXTRACT. Finally, we describe use of artificial neural network (ANN) machine learning to decode spatial paths from CA1 neural ensemble activity to predict mouse navigation of the odor plume.
SUMMARY
This protocol describes how to investigate the brain-behavior relationship in hippocampal CA1 in mice navigating an odor plume. We provide a step-by-step protocol including the surgery to access imaging of the hippocampus, behavioral training, miniscope GCaMP6f recording and processing of the brain and behavioral data to decode the mouse position from ROI neural activity.
PubMed: 38915584
DOI: 10.1101/2024.06.12.598681 -
BMC Plant Biology Jun 2024Monoterpenes are among the most important volatile aromatic compounds contributing to the flavor and aroma of grapes and wine. However, the molecular basis of...
BACKGROUND
Monoterpenes are among the most important volatile aromatic compounds contributing to the flavor and aroma of grapes and wine. However, the molecular basis of monoterpene biosynthesis has not yet been fully elucidated.
RESULTS
In our study, transcriptomics and gas chromatography-mass spectrometry (GC-MS) were used to mine candidate genes and transcription factors involved in monoterpene biosynthesis between high-monoterpene and zero-monoterpene table grape cultivars. We found that monoterpene biosynthesis was positively correlated by the expression of five genes encoding 1-deoxy-D-xylulose-5-phosphate synthase (VvDXSs), one encoding 4-hydroxy-3-methylbut-2-enyl diphosphate reductase (VvHDR), three hydroxy-3-methylglutaryl-CoA synthases (VvHMGSs) and one mevalonate kinase (VvMVK), whereas the expression of one isopentenyl diphosphate isomerase (VvIDI) and one 3-hydroxy-3-methylglutaryl-CoA reductase (VvHMGR) negatively correlated monoterpene biosynthesis. Of these genes, VvIDI was selected to validate its function in monoterpene accumulation through a transient overexpression experiment, and was shown to inhibit the biosynthesis of grape linalool and α-terpineol. Meanwhile, we found that a 64-amino acid extension sequence at the N-terminus can guide the VvIDI protein to target the chloroplast.
CONCLUSIONS
The findings of this study should help to guide future functional analysis of key genes as well as mining the potential regulatory mechanism of monoterpene biosynthesis in grapes and grape products.
Topics: Vitis; Monoterpenes; Carbon-Carbon Double Bond Isomerases; Transcriptome; Plant Proteins; Gene Expression Regulation, Plant; Gas Chromatography-Mass Spectrometry; Odorants; Hemiterpenes
PubMed: 38914931
DOI: 10.1186/s12870-024-05306-y -
Frontiers in Chemistry 2024A promising pollution control technology is cold plasma driven chemical processing. The plasma is a pulsed electric gas discharge inside a near...
A promising pollution control technology is cold plasma driven chemical processing. The plasma is a pulsed electric gas discharge inside a near atmospheric-pressure-temperature reactor. The system is energized by a continuous stream of very short high-voltage pulses. The exhaust gas to be treated flows through the reactor. The methods applied involve the development of robust cold plasma systems, industrial applications and measuring technologies. Tests of the systems were performed at many industrial sites and involved control of airborne VOC (volatile organic compound) and odor. Electrical, chemical and odor measuring data were collected with state-of-the-art methods. To explain the test data an approximate solution of global reaction kinetics of pulsed plasma chemistry was developed. It involves the Lambert function and, for convenience, a simple approximation of it. The latter shows that the amount of removal, in good approximation, is a function of a single variable. This variable is electric plasma power divided by gas flow divided by input concentration. In the results sections we show that in some cases up to 99% of volatile pollution can be removed at an acceptable energy requirement. In the final sections we look into future efficiency enhancements by implementation of (sub)nanosecond pulsed plasma and solid state high-voltage technology and by integration with catalyst technology.
PubMed: 38911992
DOI: 10.3389/fchem.2024.1386055 -
Journal of Dairy Science Jun 2024Infant formulas (IFs), the sole adequate substitute to human milk, undergo several thermal treatments during production that can damage milk proteins and promote the...
Infant formulas (IFs), the sole adequate substitute to human milk, undergo several thermal treatments during production that can damage milk proteins and promote the formation of Maillard reaction products, modifying nutritional and sensory properties. The aim of this study was to determine the impact of a minimally processing route based on membrane filtration associated with different levels of heat treatment, on the odor, taste, texture and color attributes of IFs, then to compare with those of commercial milks. Three experimental IFs (produced with membrane filtration associated with low - T, medium - T, or high thermal treatments - T) were evaluated. Triangular tests conducted with a panel of 50 adults highlighted clear disparities between all the IFs. The same panel applied the Check-All-That-Apply method to evaluate the IFs: the range of variability between T and T was similar to that between the 2 commercial IFs, and the sensory characteristics of the experimental IFs were not far from the commercial brands for flavor and texture attributes. Analysis performed on the citation frequencies for each descriptor differentiated T/T from T, but all the experimental IFs were described with positive sensory characteristics, unlike one commercial IF. Volatile organic compounds (VOCs) content of IFs with low and high thermal treatments were analyzed. Forty VOCs were identified by gas chromatography-mass spectrometry. T contained a higher quantity of VOCs than T, except for benzaldehyde (Maillard reaction product), and aldehydes (oxidation-related products) were the most represented compounds. In conclusion, the processing was associated with sensory differences among IFs, but no marked difference in flavors was found according to CATA and physicochemical analysis. Additionally, no unpleasant sensory descriptors were noted. This shows that the minimally processed route leads to IFs that could fit well within the market from a sensory point of view.
PubMed: 38908693
DOI: 10.3168/jds.2024-24937 -
Frontiers in Sports and Active Living 2024Overall physical activity (PA) has been linked to decreased olfactory dysfunction and could improve olfactory function. Additionally, decreased olfactory function can...
INTRODUCTION
Overall physical activity (PA) has been linked to decreased olfactory dysfunction and could improve olfactory function. Additionally, decreased olfactory function can contribute to reduced overall PA levels, given its association with neurodegenerative disorders. This study aims to examine the relationship between specific PA parameters (duration, frequency, intensity) and olfactory function in adults.
METHODS
A total of 3,527 participants from the National Health and Nutrition Examination Survey (NHANES) 2013-2014 underwent assessments for weekly PA duration, frequency, and intensity, alongside a smell test (including odors such as chocolate, strawberry, grape, onion, smoke, natural gas, leather, and soap). Correlation analyses and binary logistic regressions using SPSS were used to evaluate associations.
RESULTS
The total smell score exhibited small yet significant positive correlations with the duration, frequency, and volume of moderate PA (correlation coefficients ranging between 0.05 and 0.08; all ≤ 0.05) and frequency of vigorous PA (correlation coefficient of 0.05; < 0.05). For moderate PA, the duration, frequency, and volume were significantly and positively associated with the ability to correctly detect the smell of grapes while the frequency was significantly and positively associated with the ability to identify smoke and leather odors (odds ratios ranging from 1.01 to 1.07; < 0.05). For vigorous PA, the frequency of PA was positively associated with the detection of grape smell (odds ratio of 1.05; < 0.05).
CONCLUSION
Some parameters of an active lifestyle are associated with improved odds of accurately identifying odors by up to 7.4%. Moderate PA duration, frequency, and volume were linked to better olfactory scores, while high-intensity PA had limited associations.
PubMed: 38903386
DOI: 10.3389/fspor.2024.1394858 -
BMC Plant Biology Jun 2024The plant-specific YABBY transcription factor family plays important roles in plant growth and development, particularly leaf growth, floral organ formation, and...
BACKGROUND
The plant-specific YABBY transcription factor family plays important roles in plant growth and development, particularly leaf growth, floral organ formation, and secondary metabolite synthesis.
RESULTS
Here, we identified a total of 13 OfYABBY genes from the Osmanthus fragrans genome. These 13 OfYABBY genes were divided into five subfamilies through phylogenetic analysis, and genes in the same subfamily showed similar gene structures and conserved protein motifs. Gene duplication promoted the expansion of the OfYABBY family in O. fragrans. Tissue-specific expression analysis showed that the OfYABBY family was mainly expressed in O. fragrans leaves and floral organs. To better understand the role of OfYABBY genes in plant growth and development, OfYABBY12 was selected for heterologous stable overexpression in tobacco, and OfYABBY12-overexpressing tobacco leaves released significantly fewer volatile organic compounds than wild-type tobacco leaves. Overexpression of OfYABBY12 led to the downregulation of NtCCD1/4 and decreased β-ionone biosynthesis. Correspondingly, a dual-luciferase assay showed that OfYABBY12 negatively regulated the expression of OfCCD4, which promotes β-ionone synthesis. Furthermore, tobacco leaves overexpressing OfYABBY12 were curled and wrinkled and had significantly reduced leaf thickness and leaf inclusions and significantly extended flower pistils (styles).
CONCLUSION
Overall, the results suggest that the OfYABBY gene family may influence the biosynthesis of the floral scent (especially β-ionone) in O. fragrans and may regulate leaf morphogenesis and lateral organs.
Topics: Plant Leaves; Oleaceae; Flowers; Transcription Factors; Plant Proteins; Gene Expression Regulation, Plant; Phylogeny; Nicotiana; Odorants; Volatile Organic Compounds
PubMed: 38902627
DOI: 10.1186/s12870-024-05047-y -
Nature Communications Jun 2024The ability to establish associations between environmental stimuli is fundamental for higher-order brain functions like state inference and generalization. Both the...
The ability to establish associations between environmental stimuli is fundamental for higher-order brain functions like state inference and generalization. Both the hippocampus and orbitofrontal cortex (OFC) play pivotal roles in this, demonstrating complex neural activity changes after associative learning. However, how precisely they contribute to representing learned associations remains unclear. Here, we train head-restrained mice to learn four 'odor-outcome' sequence pairs composed of several task variables-the past and current odor cues, sequence structure of 'cue-outcome' arrangement, and the expected outcome; and perform calcium imaging from these mice throughout learning. Sequence-splitting signals that distinguish between paired sequences are detected in both brain regions, reflecting associative memory formation. Critically, we uncover differential contents in represented associations by examining, in each area, how these task variables affect splitting signal generalization between sequence pairs. Specifically, the hippocampal splitting signals are influenced by the combination of past and current cues that define a particular sensory experience. In contrast, the OFC splitting signals are similar between sequence pairs that share the same sequence structure and expected outcome. These findings suggest that the hippocampus and OFC uniquely and complementarily organize the acquired associative structure.
Topics: Animals; Hippocampus; Prefrontal Cortex; Neurons; Mice; Male; Mice, Inbred C57BL; Association Learning; Cues; Odorants; Memory
PubMed: 38902232
DOI: 10.1038/s41467-024-49652-9 -
Neurobiology of Disease Jun 2024Within the adult mouse subventricular zone (SVZ), neural stem cells (NSCs) produce neuroblasts and oligodendrocyte precursor cells (OPCs). T, the active thyroid hormone,...
Within the adult mouse subventricular zone (SVZ), neural stem cells (NSCs) produce neuroblasts and oligodendrocyte precursor cells (OPCs). T, the active thyroid hormone, influences renewal and commitment of SVZ progenitors. However, how regulators of T availability affect these processes is less understood. Using Mct8/Dio2 knockout mice, we investigated the role of MCT8, a TH transporter, and DIO2, the T-generating enzyme, in regulating adult SVZ-neurogliogenesis. Single-cell RNA-Seq revealed Mct8 expression in various SVZ cell types in WT mice, while Dio2 was enriched in neurons, astrocytes, and quiescent NSCs. The absence of both regulators in the knockout model dysregulated gene expression, increased the neuroblast/OPC ratio and hindered OPC differentiation. Immunostainings demonstrated compromised neuroblast migration reducing their supply to the olfactory bulbs, impairing interneuron differentiation and odor discrimination. These findings underscore the pivotal roles of MCT8 and DIO2 in neuro- and oligodendrogenesis, offering targets for therapeutic avenues in neurodegenerative and demyelinating diseases.
PubMed: 38901782
DOI: 10.1016/j.nbd.2024.106572 -
Journal of Cheminformatics Jun 2024Among the various molecular properties and their combinations, it is a costly process to obtain the desired molecular properties through theory or experiment. Using...
Among the various molecular properties and their combinations, it is a costly process to obtain the desired molecular properties through theory or experiment. Using machine learning to analyze molecular structure features and to predict molecular properties is a potentially efficient alternative for accelerating the prediction of molecular properties. In this study, we analyze molecular properties through the molecular structure from the perspective of machine learning. We use SMILES sequences as inputs to an artificial neural network in extracting molecular structural features and predicting molecular properties. A SMILES sequence comprises symbols representing molecular structures. To address the problem that a SMILES sequence is different from actual molecular structural data, we propose a pretraining model for a SMILES sequence based on the BERT model, which is widely used in natural language processing, such that the model learns to extract the molecular structural information contained in the SMILES sequence. In an experiment, we first pretrain the proposed model with 100,000 SMILES sequences and then use the pretrained model to predict molecular properties on 22 data sets and the odor characteristics of molecules (98 types of odor descriptor). The experimental results show that our proposed pretraining model effectively improves the performance of molecular property prediction SCIENTIFIC CONTRIBUTION: The 2-encoder pretraining is proposed by focusing on the lower dependency of symbols to the contextual environment in a SMILES than one in a natural language sentence and the corresponding of one compound to multiple SMILES sequences. The model pretrained with 2-encoder shows higher robustness in tasks of molecular properties prediction compared to BERT which is adept at natural language.
PubMed: 38898528
DOI: 10.1186/s13321-024-00848-7