Differential gene expression analysis following olfactory learning in honeybee (Apis mellifera L.)

Abstract

Insects change their stimulus-response through the perception of associating these stimuli with important survival events such as rewards, threats, and mates. Insects develop strong associations and relate them to their experiences through several behavioral procedures. Among the insects, Apis species, Apis mellifera ligustica are known for their outstanding ability to learn with tremendous economic importance. Apis mellifera ligustica has a strong cognitive ability and promising model species for investigating the neurobiological basis of remarkable olfactory learning abilities. Here we evaluated the olfactory learning ability of A. mellifera by using the proboscis extension reflex (PER) protocol. The brains of the learner and failed-learner bees were examined for comparative transcriptome analysis by RNA-Seq to explain the difference in the learning capacity. In this study, we used an appetitive olfactory learning paradigm in the same age of A. mellifera bees to examine the differential gene expression in the brain of the learner and failed-learner. Bees that respond in 2nd and 3rd trials or only responded to 3rd trials were defined as learned bees, failed-learner individuals were those bees that did not respond in all learning trials The results indicate that the learning ability of learner bees was significantly higher than failed-learner bees for 12 days. We obtained approximately 46.7 and 46.4 million clean reads from the learner bees failed-learner bees, respectively. Gene expression profile between learners’ bees and failed-learners bees identified 74 differentially expressed genes, 57 genes up-regulated in the brains of learners and 17 genes were down-regulated in the brains of the bees that fail to learn. The qRT-PCR validated the differently expressed genes. Transcriptome analyses revealed that specific genes in learner and failed-learner bees either down-regulated or up-regulated play a crucial role in brain development and learning behavior. Our finding suggests that down-regulated genes of the brain involved in the integumentary system, storage proteins, brain development, sensory processing, and neurodegenerative disorder may result in reduced olfactory discrimination and olfactory sensitivity in failed-learner bees. This study aims to contribute to a better understanding of the olfactory learning behavior and gene expression information, which opens the door for understanding of the molecular mechanism of olfactory learning behavior in honeybees.

Decoding bee cleptoparasitism through comparative transcriptomics of Coelioxoides waltheriae and its host Tetrapedia diversipes

“…Nonetheless, the MRJP-like genes, as part of this family, seem to be restricted to Hymenoptera 56 . Even though these genes have been associated with olfactory learning—particularly regarding mrjp1 expression in the mushroom body (Kenyon cells) 31 , 57 , 58 —and functional studies have shown that MRJPs may have immunoregulatory and antibacterial effects 56 , in bees, MRJPs are mostly associated with larvae feeding, development and with the regulation of phenotypic plasticity and age-polyethism in workers 59 . In honeybees, MRJPs are known to be essential components of the larvae diet, with MRJP1–3 and 5 being the most abundant proteins of larval food 56 .…”

“…In Drosophila , for instance, Unc80 is necessary for circadian rhythmicity 124 . It is thought that Unc80 may also be involved in bee learning and memory 31 . The gene Hr38, a nuclear receptor , is involved in the transcriptional control of the dopamine synthesis pathway 127 , the cuticle gene expression 128 , and the ecdysteroid signaling pathways 129 .…”

“…Recent studies have successfully employed comparative transcriptomic analysis to unveil molecular features related to complex behaviors. For instance, transcriptomics studies in bees have helped to better understand the molecular pathways related to the honeybee (waggle) dance 29 , Varroa sensitive hygiene behaviour 30 , olfactory 31 and visual 32 learning, diapause 33 , 34 , and evolution of task division 35 – 37 . In this context, herein we use gene expression data to perform a comparative analysis between the correspondent reproductive life stages of C. waltheriae and its host, T. diversipes .…”

Production and Quality Characteristics of Royal Jelly in Relation to Available Natural Food Resources

“…However, this belief has not been scientifically proven [21]. The acceptance of artificial queen cells by bees is influenced by various factors, including the season of RJ production and genetic factors like the breed [22,23]. Also, the availability of food supplies, particularly pollen and nectar, fluctuates throughout the year, affecting the stimulation of bee glands.…”

Imbalance in Unc80 RNA Editing Disrupts Dynamic Neuronal Activity and Olfactory Perception

“…Intriguingly, mutations in Unc80 have been shown to impact various biological processes. For instance, in honeybees, differences in Unc80 expression, observed through NGS-Seq of brains from odor-learning tasks, suggest a correlation between Unc80 and olfactory learning [ 32 ]. In C. elegans , mutations in Unc80 led to impaired avoidance behavior to Methyl salicylate, which could be significantly mitigated by neuron-specific transgenic rescue, further underscoring Unc80 ’s role in neural function [ 33 ].…”