Understanding Of Chemical Communication Research Articles

Phenethylamine Is a Potential Density Stress Pheromone in Turbot (Scophthalmus maximus)

Pheromones play a vital role in regulating fish behavior, including reproduction, aggregation, hazard recognition and food location. To gain a better understanding of chemical communication in fish produced by density changes, this study analyzed the metabolites released by turbot (Scophthalmus maximus) under different stocking densities. The experiment was conducted at low (LD: 3.01 kg/m2), medium (MD: 6.62 kg/m2) and high (HD: 10.84 kg/m2) densities for 15 days. High-throughput non-targeted metabolomics (LC-MS/MS) was used to identify variations in metabolites released into the aquatic environment by turbot at different densities. Results showed that 29 and 47 metabolites were significantly upregulated in the MD and HD groups, respectively, compared with the LD group. Among them, hexadecanedioic acid, xanthine, phenethylamine, proline and styrene were significantly upregulated in the MD vs. LD, HD vs. MD and HD vs. LD. The VIP diagram of OPLS-DA alignment showed that phenethylamine was the most important metabolite shared by MD vs. LD, HD vs. MD and HD vs. LD. Key gene changes in the GH/IGF-1 signaling pathway, HPI axis of turbot were studied using qRT-PCR for density treatment. The results demonstrated that the expression of GH, GHR and IGF-1 was significantly lower, while the expression of CRH and ACTH was higher in the HD group. Additionally, plasma levels of cortisol, glucose, triglycerides and T3 were also highest in the HD group compared with the LD and MD groups. Phenylethylamine concentration was positively correlated with the HPI axis and negatively correlated with the GH/IGF-1 signaling pathway. To investigate the impact of phenethylamine accumulation on turbot, an acute treatment experiment with phenethylamine was set up. Its concentration in the aquatic environment was set at 0 (CON), 10−7 (LP) and 10−5 (HP) mol/L via exogenous addition, and turbot were exposed to these environments for 2 days. There was a high degree of concordance between the GH/IGF-1 signaling pathway (GH, GHR, IGF-1), HPI axis (CRH, ACTH) and plasma physiological changes (cortisol, glucose, triglycerides, T3) in the phenethylamine-treated group and the density-treated group. Therefore, accumulation of phenethylamine with increasing stocking density may be a potential cause of density stress. Phenylethylamine has a dose-dependent and trace effect as a pheromone.

Identification of sex pheromone in Macdunnoughia crassisigna Warren (Lepidoptera: Noctuidae) and field optimization of the sex attractant.

Sex pheromones have proven to be a viable tool for monitoring and controlling pests and is an important part of integrated pest management (IPM). The noctuid moth Macdunnoughia crassisigna Warren poses a significant threat as a defoliator pest, impacting soybean and cruciferous vegetable production and quality in East Asia. However, a lack of comprehensive knowledge about its sexual chemical signaling hampers the development of semiochemical-based IPM approaches for M. crassisigna. We first determined the mating rhythms of M. crassisigna. We then collected pheromones from the sex glands of virgin females at the mating peak and analyzed their components using gas chromatography-electroantennogram detection analysis. The results showed that three components elicited significant electrophysiological responses in male antennae. Gas chromatography-mass spectrometry analysis characterized these components as (Z)-7-dodecene acetate (Z7-12:OAc), (Z)-9-tetradecene acetate (Z9-14:OAc), and (Z)-11-hexadecen-1-ol (Z11-16:OH). Further field experiments indicated that the mixture of Z7-12:OAc and Z9-14:OAc at a ratio of 3:1 displayed significant attractivity to males, confirming its role as a putative sex pheromone of M. crassisigna. Long-term monitoring tests showed that traps baited with these pheromone lures effectively mirrored the population dynamics of M. crassisigna. This study successfully identified and validated the sex pheromone released by female M. crassisigna and formulated potent sex lures for field-based pest monitoring. These findings enriched our understanding of chemical communication in Noctuidae and laid a foundation for developing practical monitoring and control methods against M. crassisigna. © 2023 Society of Chemical Industry.

The chemistry and histology of sexually dimorphic mental glands in the freshwater turtle, Mauremys leprosa.

Despite evidence from anatomy, behavior and genomics indicating that the sense of smell in turtles is important, our understanding of chemical communication in this group is still rudimentary. Our aim was to describe the microanatomy of mental glands (MGs) in a freshwater turtle, Mauremys leprosa (Geoemydidae), and to assess the chemical composition of their secretions with respect to variation among individuals and between sexes. MGs are paired sac-like organs on the gular region of the neck and are dimorphic in this species with males having fully functional holocrine glands while those of females appear non-secretory and vestigial. In adult males, the glandular epithelium of the inner portion of the gland provides exocytotic products as well as cellular debris into the lumen of the gland. The contents of the lumen can be secreted through the narrow duct portion of the gland ending in an orifice on the surface of the skin. Females have invaginated structures similar in general outline to male glands, but lack a glandular epithelium. Using gas chromatography coupled to mass spectrometry, we identified a total of 61 compounds in mental gland secretions, the most numerous being carboxylic acids, carbohydrates, alkanes, steroids and alcohols. The number of compounds per individual varied widely (mean (median) ± SD = 14.54 (13) ± 8.44; min = 3; max = 40), but only cholesterol was found in all samples. We found that the relative abundances of only six chemicals were different between the sexes, although males tended to have larger amounts of particular compounds. Although the lipid fraction of mental gland secretions is rich in chemical compounds, most occur in both sexes suggesting that they are metabolic byproducts with no role in chemical signaling. However, the relative amounts of some compounds tended to be higher in males, with significantly larger amounts of two carboxylic acids and one steroid, suggesting their putative involvement in chemical communication.

Nocturnal Bee Pollinators Are Attracted to Guarana Flowers by Their Scents.

Floral scent is an important component of the trait repertoire of flowering plants, which is used to attract and manipulate pollinators. Despite advances during the last decades about the chemicals released by flowers, there is still a large gap in our understanding of chemical communication between flowering plants and their pollinators. We analyzed floral scents of guarana (Paullinia cupana, Sapindaceae), an economically important plant of the Amazon, using chemical analytical approaches, and determined the attractiveness of the scent to its nocturnal bee pollinators using behavioral assays in the field. Pollen loads of attracted bees were also analyzed. Inflorescences of guarana emit strong scents, both during day and at night, with some semi-quantitative differences between day- and night-time scents. Synthetic scent mixtures containing some of the identified floral scent components, including the most abundant ones, i.e., linalool and (E)-β-ocimene, successfully attracted the nocturnal Megalopta bee pollinators. Pollen analyses revealed that many of the attracted bees had pollen grains from previous visits to guarana flowers on their bodies. Overall, our data show that guarana flowers attract nocturnal bee visitors by their strong scents and suggest that the chemical communication between this plant and its pollinators is a key component in crop production of this economically important plant species.

How to tackle chemical communication? Relative proportions versus semiquantitative determination of compounds in lizard chemical secretions.

Knowledge about chemical communication in some vertebrates is still relatively limited. Squamates are a glaring example of this, even when recent evidences indicate that scents are involved in social and sexual interactions. In lizards, where our understanding of chemical communication has considerably progressed in the last few years, many questions about chemical interactions remain unanswered. A potential reason for this is the inherent complexity and technical limitations that some methodologies embody when analyzing the compounds used to convey information. We provide here a straightforward procedure to analyze lizard chemical secretions based on gas chromatography coupled to mass spectrometry that uses an internal standard for the semiquantification of compounds. We compare the results of this method with those obtained by the traditional procedure of calculating relative proportions of compounds. For such purpose, we designed two experiments to investigate if these procedures allowed revealing changes in chemical secretions 1) when lizards received previously a vitamin dietary supplementation or 2) when the chemical secretions were exposed to high temperatures. Our results show that the procedure based on relative proportions is useful to describe the overall chemical profile, or changes in it, at population or species levels. On the other hand, the use of the procedure based on semiquantitative determination can be applied when the target of study is the variation in one or more particular compounds of the sample, as it has proved more accurate detecting quantitative variations in the secretions. This method would reveal new aspects produced by, for example, the effects of different physiological and climatic factors that the traditional method does not show.

The chemical‐speciation hypothesis in Liolaemus: a response to Pincheira‐Donoso

The chemical‐speciation hypothesis in <i><scp>L</scp>iolaemus</i>: a response to <scp>P</scp>incheira‐<scp>D</scp>onoso

Chopper-stabilized gas chromatography-electroantennography: Part I. Background, signal processing and example

A new method that can improve gas-chromatography-electroantennographic detection (GC-EAD) by orders of magnitude through a technique known as chopper stabilization combined with matched filtering in colored noise is presented. The EAD is a physiological recording from the antenna of an insect which can be used to find compounds in the GC effluent that the antenna is able to detect, having important applications for pest control and understanding of chemical communication in nature. The new method is demonstrated with whole-animal male Helicoverpa zea antennal preparations for detection of major pheromone component (cis-11-hexadecenal) and compared to results obtained using traditional EAD recording techniques. Results indicate that chopper stabilization under these circumstances can increase odorant detection performance by a factor of approximately 104 over traditional methods. The time course of the response of the antenna is also better resolved under chopped conditions. Although the degree of improvement is expected to vary with insect species, odor, and insect preparation, under most circumstances a more sensitive and robust GC-EAD instrument will result from the application of this technique.