The evolutionary expansion of sensory neuron populations detecting important environmental cues is widespread, but functionally enigmatic. We investigated this phenomenon through comparison of homologous olfactory pathways of Drosophila melanogaster and its close relative Drosophila sechellia, an extreme specialist for Morinda citrifolia noni fruit. D. sechellia has evolved species-specific expansions in select, noni-detecting olfactory sensory neuron (OSN) populations, through multigenic changes. Activation and inhibition of defined proportions of neurons demonstrate that OSN number increases contribute to stronger, more persistent, noni-odour tracking behaviour. These expansions result in increased synaptic connections of sensory neurons with their projection neuron (PN) partners, which are conserved in number between species. Surprisingly, having more OSNs does not lead to greater odour-evoked PN sensitivity or reliability. Rather, pathways with increased sensory pooling exhibit reduced PN adaptation, likely through weakened lateral inhibition. Our work reveals an unexpected functional impact of sensory neuron population expansions to explain ecologically-relevant, species-specific behaviour.

OBJECTIVE: This is a protocol for a Cochrane Review (intervention). The objectives are as follows: To evaluate the benefits and harms of olfactory stimulation with different odorants in the NICU for promoting development and preventing morbidity in preterm infants.

Methylation represents a crucial class of modification that orchestrates a spectrum of regulatory roles in plants, impacting ornamental characteristics, growth, development, and responses to abiotic stress. The establishment and maintenance of methylation involve the coordinated actions of multiple regulatory factors. Methyltransferases play a pivotal role by specifically recognizing and methylating targeted sites, which induces alterations in chromatin structure and gene expression, subsequently influencing the release of volatile aromatic substances and the accumulation of pigments in plant petals. In this paper, we review the regulatory mechanisms of methylation modification reactions and their effects on the changes in aromatic substances and pigments in plant petals. We also explore the potential of methylation modifications to unravel the regulatory mechanisms underlying aroma and color in plant petals. This aims to further elucidate the synthesis, metabolism, and regulatory mechanisms of various methylation modifications related to the aroma and color substances in plant petals, thereby providing a theoretical reference for improving the aroma and color of plant petals.

Fragrance is a valuable trait in rice varieties, with its aroma significantly influencing consumer preference. In this study, we conducted comprehensive metabolome and transcriptome analyses to elucidate the genetic and biochemical basis of fragrance in the Shangsixiangnuo (SSXN) variety, a fragrant indica rice cultivated in Guangxi, China. Through sensory evaluation and genetic analysis, we confirmed SSXN as strongly fragrant, with an 806 bp deletion in the BADH2 gene associated with fragrance production. In the metabolome analysis, a total of 238, 233, 105 and 60 metabolic compounds exhibited significant changes at the seedling (S), reproductive (R), filling (F), and maturation (M) stages, respectively. We identified four compounds that exhibited significant changes in SSXN across all four development stages. Our analyses revealed a significant upregulation of 2-acetyl-1-pyrroline (2AP), the well-studied aromatic compound, in SSXN compared to the non-fragrant variety. Additionally, correlation analysis identified several metabolites strongly associated with 2AP, including ethanone, 1-(1H-pyrrol-2-yl)-, 1H-pyrrole, and pyrrole. Furthermore, Weighted Gene Co-expression Network Analysis (WGCNA) analysis highlighted the magenta and yellow modules as particularly enriched in aroma-related metabolites, providing insights into the complex aromatic compounds underlying the fragrance of rice. In the transcriptome analysis, a total of 5582, 5506, 4965, and 4599 differential expressed genes (DEGs) were identified across the four developmental stages, with a notable enrichment of the common pathway amino sugar and nucleotide sugar metabolism in all stages. In our correlation analysis between metabolome and transcriptome data, the top three connected metabolites, phenol-, 3-amino-, and 2AP, along with ethanone, 1-(1H-pyrrol-2-yl)-, exhibited strong associations with transcripts, highlighting their potential roles in fragrance biosynthesis. Additionally, the downregulated expression of the P4H4 gene, encoding a procollagen-proline dioxygenase that specifically targets proline, in SSXN suggests its involvement in proline metabolism and potentially in aroma formation pathways. Overall, our study provides comprehensive insights into the genetic and biochemical mechanisms underlying fragrance production in rice, laying the foundation for further research aimed at enhancing fragrance quality in rice breeding programs.

Chardonnay is one of the most popular white grape wine varieties in the world, but this wine lacks typical aroma, considered a sensory defect. Our research group identified a Chardonnay bud sport with typical muscat characteristics. The goal of this work was to discover the key candidate genes related to muscat characteristics in this Chardonnay bud sport to reveal the mechanism of muscat formation and guide molecular design breeding. To this end, HS-SPME-GC-MS and RNA-Seq were used to analyze volatile organic compounds and the differentially expressed genes in Chardonnay and its aromatic bud sport. Forty-nine volatiles were identified as potential biomarkers, which included mainly aldehydes and terpenes. Geraniol, linalool, and phenylacetaldehyde were identified as the main aroma components of the mutant. The GO, KEGG, GSEA, and correlation analysis revealed HMGR, TPS1, TPS2, TPS5, novel.939, and CYP450 as key genes for terpene synthesis. MAO1 and MAO2 were significantly downregulated, but there was an increased content of phenylacetaldehyde. These key candidate genes provide a reference for the development of functional markers for muscat varieties and also provide insight into the formation mechanism of muscat aroma.

There is considerable interest in the use of essential oils for food preservation, but their effect on the aroma profile of a product is poorly understood. This study investigated the effect of thyme essential oil (EO) addition at increasing concentrations (0.005, 0.01, 0.02, and 0.03% v/w) on the volatile compound composition of vacuum-packed minced turkey meat after storage for 8 days at 1-2 °C. The aroma profile of the meat was determined using the HS-SPME/GCMS (headspace solid-phase microextraction/gas chromatography-mass spectrometry) method. The results were also analysed by PCA (principal component analysis). The addition of thyme EO had a modifying effect on the aroma profile of meat-derived components, e.g., the formation of benzeneacetaldehyde, benzyl alcohol, 4,7-dimethylbenzofuran, hexathiane, hexanal, and 1-hexanol was reduced and the appearance of 9-hexadecenoic acid was observed in the stored samples. The increase in EO concentration affected the levels of its individual components in the meat headspace in different ways. In terms of fat rancidity indices, even a 0.005% addition of this essential oil significantly reduced the peroxide value. Quantitative descriptive analysis (QDA) showed that the addition of thyme EO reduced or masked the intensity of unpleasant odours associated with meat spoilage. In the aroma analysis, the turkey with 0.02% v/w EO scored highest, and pleasant citrus notes were found.

This work used headspace solid-phase microextraction with gas chromatography-mass spectrometry (HS-SPME-GC-MS) to analyze the volatile components of hydrosols of Citrus × aurantium \'Daidai\' and Citrus × aurantium L. dried buds (CAVAs and CADBs) by immersion and ultrasound-microwave synergistic-assisted steam distillation. The results show that a total of 106 volatiles were detected in hydrosols, mainly alcohols, alkenes, and esters, and the high content components of hydrosols were linalool, α-terpineol, and trans-geraniol. In terms of variety, the total and unique components of CAVA hydrosols were much higher than those of CADB hydrosols; the relative contents of 13 components of CAVA hydrosols were greater than those of CADB hydrosols, with geranyl acetate up to 15-fold; all hydrosols had a citrus, floral, and woody aroma. From the pretreatment, more volatile components were retained in the immersion; the relative contents of linalool and α-terpineol were increased by the ultrasound-microwave procedure; and the ultrasound-microwave procedure was favorable for the stimulation of the aroma of CAVA hydrosols, but it diminished the aroma of the CADB hydrosols. This study provides theoretical support for in-depth exploration based on the medicine food homology properties of CAVA and for improving the utilization rate of waste resources.

Chronic wasting disease (CWD) has become a major concern among those involved in managing wild and captive cervid populations. CWD is a fatal, highly transmissible spongiform encephalopathy caused by an abnormally folded protein, called a prion. Prions are present in a number of tissues, including feces and urine in CWD infected animals, suggesting multiple modes of transmission, including animal-to-animal, environmental, and by fomite. CWD management is complicated by the lack of practical, non-invasive, live-animal screening tests. Recently, there has been a focus on how the volatile odors of feces and urine can be used to discriminate between infected and noninfected animals in several different species. Such a tool may prove useful in identifying potentially infected live animals, carcasses, urine, feces, and contaminated environments. Toward this goal, dogs were trained to detect and discriminate CWD infected individuals from non-infected deer in a laboratory setting. Dogs were tested with novel panels of fecal samples demonstrating the dogs\' ability to generalize a learned odor profile to novel odor samples based on infection status. Additionally, dogs were transitioned from alerting to fecal samples to an odor profile that consisted of CWD infection status with a different odor background using different sections of gastrointestinal tracts. These results indicated that canine biodetectors can discriminate the specific odors emitted from the feces of non-infected versus CWD infected white-tailed deer as well as generalizing the learned response to other tissues collected from infected individuals. These findings suggest that the health status of wild and farmed cervids can be evaluated non-invasively for CWD infection via monitoring of volatile metabolites thereby providing an effective tool for rapid CWD surveillance.

Social animals need to keep track of other individuals in their group to be able to adjust their behaviour accordingly and facilitate group cohesion. This recognition ability varies across species and is influenced by cognitive capacities such as learning and memory. In reptiles, particularly Squamates (lizards, snakes, and worm lizards), chemical communication is pivotal for territoriality, reproduction, and other social interactions. However, the cognitive processes underlying these social interactions remain understudied. In our study, we examined the ability of male and female Tokay geckos (Gekko gecko) to chemically differentiate familiar and unfamiliar mating partners. Our findings suggest that both sexes can make this distinction, with males responding more to the odour of a familiar mate, and females responding more to unfamiliar mates. The lizards maintained their discriminatory abilities for two to three weeks but not up to six weeks after separation. This research highlights the efficacy of using odours as social stimuli for investigating social cognition in lizards, a promising avenue to better understand social cognition in these animals.

Butterflies, like many insects, use gustatory and olfactory cues innately to assess the suitability of an oviposition site and are able to associate colours and leaf shapes with an oviposition reward. Studies on other insects have demonstrated that the quality of the reward is a crucial factor in forming associative memory. We set out to investigate whether the large cabbage white Pieris brassicae (Linnaeus) has the ability to associate an oviposition experience with a neutral olfactory cue. In addition, we tested whether the strength of this association is dependent on the gustatory response to the glucosinolate sinigrin, which is a known oviposition stimulus for P. brassicae. Female butterflies were able to associate a neutral odour with an oviposition experience after a single oviposition experience, both in a greenhouse and in a semi-natural outdoor setting. Moreover, butterflies performed best when trained with concentrations of sinigrin that showed the strongest response by specific gustatory neurons on the forelegs. Our study provides novel insight into the role of both gustatory and olfactory cues during oviposition learning in lepidopterans and contributes to a better understanding of how these insects might be able to adapt to a rapidly changing environment.