Lateralization in the Invertebrate Brain: Left-Right Asymmetry of Olfaction in Bumble Bee, Bombus terrestris

Brain and behavioural lateralization at the population level has been recently hypothesized to have evolved under social selective pressures as a strategy to optimize coordination among asymmetrical individuals. Evidence for this hypothesis have been collected in Hymenoptera: eusocial honey bees showed olfactory lateralization at the population level, whereas solitary mason bees only showed individual-level olfactory lateralization. Here we investigated lateralization of odour detection and learning in the bumble bee, Bombus terrestris L., an annual eusocial species of Hymenoptera. By training bumble bees on the proboscis extension reflex paradigm with only one antenna in use, we provided the very first evidence of asymmetrical performance favouring the right antenna in responding to learned odours in this species. Electroantennographic responses did not reveal significant antennal asymmetries in odour detection, whereas morphological counting of olfactory sensilla showed a predominance in the number of olfactory sensilla trichodea type A in the right antenna. The occurrence of a population level asymmetry in olfactory learning of bumble bee provides new information on the relationship between social behaviour and the evolution of population-level asymmetries in animals

Clinical Features, Cardiovascular Risk Profile, and Therapeutic Trajectories of Patients with Type 2 Diabetes Candidate for Oral Semaglutide Therapy in the Italian Specialist Care

Introduction: This study aimed to address therapeutic inertia in the management of type 2 diabetes (T2D) by investigating the potential of early treatment with oral semaglutide. Methods: A cross-sectional survey was conducted between October 2021 and April 2022 among specialists treating individuals with T2D. A scientific committee designed a data collection form covering demographics, cardiovascular risk, glucose control metrics, ongoing therapies, and physician judgments on treatment appropriateness. Participants completed anonymous patient questionnaires reflecting routine clinical encounters. The preferred therapeutic regimen for each patient was also identified. Results: The analysis was conducted on 4449 patients initiating oral semaglutide. The population had a relatively short disease duration (42%  60% of patients, and more often than sitagliptin or empagliflozin. Conclusion: The study supports the potential of early implementation of oral semaglutide as a strategy to overcome therapeutic inertia and enhance T2D management

Mean number ± SE of sensilla for the right antenna (white bars) and for the left antenna (grey bars) of <i>Bombus terrestris</i> foragers in function of the segment number.

<p>Putative olfactory sensilla: placodea, trichodea type A, basiconica, coeloconica (upper graphs). Non-olfactory sensilla: trichodea type B, ampullacea (lower graphs). Data were analyzed by ANOVA with antenna, segment and sensilla as within-subjects factor. An overall antenna effect emerged (F_1,13 = 22.56, p<0.001). A significant effect of segment (F_7,91 = 43.20, p<0.001), sensillum type (F_5,65 = 396.40, p<0.001) and antenna per sensillum type interaction (F_5,65 = 17.89, p<0.001) was revealed. Asterisks indicate a significant right antenna dominance in the number of olfactory sensilla trichodea type A (F_1,13 = 21.26, p<0.001). No significant antenna effects were found in the number of sensilla basiconica (F_1,13 = 1.47, p = 0.247), sensilla coeloconica (F_1,13 = 3.61, p = 0.08) and sensilla placodea (F_1,13 = 0.97, p = 0.342). Analyses of non-olfactory sensilla did not reveal any significant difference between right and left antennae in the number of sensilla trichodea type B (F_1,13 = 3.45, p = 0.086) and sensilla ampullacea (F_1,13 = 0.10, p = 0.755).</p

Scanning electron micrographs of <i>Bombus terrestris</i> foragers.

<p>(a) ventral view of a medial segment of the flagellum; (b) details of sensillum trichodeum type A, type B and sensillum placodeum; (c) details of sensillum coeloconicum, ampullaceum, trichodeum type B and setae; (d) detail of sensillum basiconicum. Am, sensillum ampullaceum; Ba, sensillum basiconicum; Co, sensillum coeloconicum; Pl, sensillum placodeum; Se, seta; TA, sensillum trichodeum type A; TB, sensillum trichodeum type B.</p

Mean EAG ± SE absolute responses (mV) of right (unbroken lines with black squares) and left (dotted lines with empty squares) antenna of <i>Bombus terrestris</i> foragers (N = 20) to isoamyl acetate (left) and (-)-linalool (right) at five different doses (Log₁₀ µg/µl).

<p>No significant differences were found between the antennae (ANOVA: F_1,19 = 2.72, p = 0.12). Significant effects of both dose (ANOVA: F_4,16 = 42.52, p<0.001) and scent (ANOVA: F_1,76 = 107.61, p<0.001) were revealed.</p

Behavioural asymmetry during recall of short-term odour memory in <i>Bombus terrestris</i> foragers, after trained on the proboscis extension reflex.

<p>Mean percent correct responses ± SE 1 h after (-)-linalool conditioning with both antennae in use (white bars), right antenna in use only (grey bars), or left antenna in use only (black bars). A significant effect of the antenna in use was found (ANOVA: F_2,27 = 80.86, p<0.001). Post hoc comparison using Tukey HSD test revealed a significant difference between bees using their right and their left antenna (p<0.001), and between bees using their left antenna and those using both antennae (p<0.001) and between bees using their right antenna and bees using both antennae (p<0.01).</p