Project description:Sibling care is a hallmark of the social insects, but its evolution remains challenging to explain. The hypothesis that sibling care evolved from ancestral maternal care in the primitively eusocial insects has been elaborated to involve heterochronic changes in gene expression. This elaboration leads to the prediction that workers in these species will show patterns of gene expression more similar to foundress queens, who express maternal care behavior, than to established queens engaged solely in reproductive behavior. We tested this idea in the bumblebee Bombus terrestris using a microarray platform with ca. 4,500 genes. Unlike in the wasp Polistes metricus, in which support for the above prediction has been obtained, we found that patterns of brain gene expression in foundress and queen bumblebees were more similar to each other than to workers. However, comparisons of lists of differentially expressed genes derived from this study and gene lists from microarray studies in Polistes and the honeybee Apis mellifera suggest that there is a shared set of genes involved in the regulation of related social behaviors across independent eusocial lineages. Together, these results suggest that the multiple independent evolutions of eusociality in the insects involved a combination of shared and different mechanisms.
Project description:As a matter of fact, honeybees are vital for the pollination of more than 80 crops of agricultural interest. However, population decline has become an important global issue causing significant concerns among agricultural experts and the broader public. For this, parasites are known to be the major culprits responsible for the losses of millions of honeybee colonies so far. Among these parasites, Varroa destructor has been identified as a major cause for global losses in Western honeybee (Apis mellifera) colonies. Hygienic behavior (HB), on the other hand, is a collective response by adult honeybees to defend against parasites and diseases that is known to involve in resistance towards Varroosis. Even with the efforts made to elucidate the molecular mechanism underlying HB, it is still not understood. In our study, we have studied the proteomic correlates to HB using a honeybee line (selected for Varroa-specific HB for over a decade in Germany). We sampled individual worker bees from this line that showed HB after closer infrared video observations and compared the proteomes of their mushroom bodies and antennae with those of workers that came from the same set of colonies but didn't show the behaviour. Furthermore, we compared the pupal hemolymph for worker bees of the selected HB line and a control line using state-of-the art techniques of proteomics. We identified a total of 8609 proteins (covered >55% of the honeybee proteome) from these three honeybee tissues. This is the most comprehensive proteomic study of the honeybee HB to date, and the first to focus on individual bees expressing Varroa-specific HB. These results have significantly advanced our knowledge on the biology underlining HB to a new level. The uniquely found functional classes and pathways by the proteins identified in each tissue suggest that hygienic bees have shaped distinct proteome settings to underpin the HB. Moreover, during analysis of pupal hemolymph proteome, the HB-line has adapted a unique strategy to boost an individual and social immunity and drove pupal organogenesis via energy metabolism and protein biosynthesis. Moreover, in the mushroom bodies of different HB phenotypic worker bees, the hygienic bees have enhanced their neuronal sensitivity to promote the execution of HB by activation of synaptic vesicles and calcium channel activities. Moreover, in the antennae of two HB phenotypic worker bees, the hygienic bees have demonstrated strengthening of their sensitivity associated with olfactory senses and signal transmissions, which is important to input a strong signal to the mushroom bodies and initiate HB. In conclusion, our novel findings have significantly extended our understandings of the molecular mechanisms that underline the HB to combat Varroa infestation. Furthermore, we identified a wide array of novel markers that are useful for accelerating marker associated selection of HB to aid in the natural resistance to a parasite blamed for a global decline in honeybee health.
Project description:We performed gene expression studies in worker bees displaying quantitative genetic differences in hygienic behavior derived from backcrosses. We established hybrid queens and backcrossed to high and low performing hygienic behavioral sources and scored the hygienic behavior of single worker bees under same environmental conditions.
Project description:Specific genes or encoded proteins are involved in regulating various learning models of different species through certain signaling pathways,but whether there are also regulatory genes during bimodal learning and memory is largely unknown. Using a multi-omics approach to examine gene expression changes in bees brain performed with three different learning assays, a general up-regulation of genes and proteins were observed in bimodal learning compared to controls. Protein-protein network predictions of differential proteins together with FISH assays suggest ALDH7A1 may be involved in regulation of bimodal learning and memory. Injecting siRNA-ALDH7A1 to the bee brain results in significant inhibition the expressions of ALDH7A1 and regucalcin, and increase β-alanine content. Interestingly, we found that loss of ALDH7A1 only affect visual-olfactory bimodal learning and memory, but not single visual or olfactory conditioned learning after ALDH7A1-RNAi in bees. Therefore, our data suggests that ALDH7A1 may affect bimodal learning and memory though controlling β-alanine related plasticity mechanisms.
Project description:Here we show that regions of the honeybee brain involved in visual processing and learning and memory show a genomic response to distance information. Using a method that separates effects of perceived distance from effects of actual distance flown, we found that individuals forced to shift from a short to a perceived long distance to reach a feeding site showed differences in gene expression in the optic lobes and mushroom bodies relative to individuals that continued to perceive flying a short distance.
Project description:Background: Honey bee is a major insect used for pollination of a number of commercial crops worldwide. However, the number of managed honey bee colonies has recently declined in several countries, and a number of possible causes are proposed. Although the use of honey bees for pollination can be considered as disruption of the habitat, its effects on honey bees' physiology have never been addressed. In Japan, more than 100 thousands colonies are annually used for pollination, and intriguingly 80% of them are used in greenhouses. Recently, honey bee colonies have often collapsed when they are introduced into greenhouses. Thus, to suppress colony collapses and maintain the number of worker bees in the colonies are essential for successful long-term pollination in greenhouses and recycling honey bee colonies. Honey bee hives were installed into strawberry and eggplant greenhouses, and then the gene expression profiles of the honey bees were examined at the different time periods. Total 16 samples with two replicates were analyzed.
Project description:The genome of the western honey bee (Apis mellifera) harbours ten different major royal jelly protein genes (mrjp1-10) which originate from a single-copy precursor via gene duplication. The evolutionary fate of duplicated genes is eventually determined over time as to result in loss due to pseudogenization, or in preservation due to neo- or sub-functionalization. Both fates were already observed in the mrjp gene cluster, as only mrjp1 - 9 are expressed, whereas mrjp10 was pseudogenized and represents an incomplete gene copy. In contrast, MRJP1 underwent neofunctionalization and developed an essential function within the food jelly of queen larvae, to guaranty the survival of the whole colony. We here show combining quantitative real time PCR with quantitative mass spectrometry that expression of most mrjps (mrjp1-5 and 7) shows an age dependent pattern in worker hypopharyngeal glands as well as in brains. Expression increases after hatching until the nurse bee period and is followed by a decrease in older workers that forage for different plant products. Mrjp6 expression deviates considerably from the expression profiles of the other mrjps and transcript abundance does not correlate with protein amount. Thus, either mrjp6 does fulfil a total different function or it might be on its way to pseudogenization. Furthermore, a tissue-specific function of the proteins MRJP8 and 9 in the hypopharyngeal glands and the brain can be excluded, suggesting a more general physiological than a nutritive function for both gene products.
Project description:Flenniken - Honey bee gene expression microarray experimental design<br>To minimize variability between samples all arrayed bees were obtained from a single brood comb from a naturally mated queen, therefore all the bees were age-matched half-sisters. The bees selected for microarray analysis of virus (Sindbis-eGFP) co-injected with either virus-specific-dsRNA (vs-dsRNA) or non-specific dsRNA (ns-dsRNA) exhibited the reduced virus phenotype that was seen in the majority of the bees assayed. The five representative bees from each condition (v, v+vs-dsRNA, v+ns-dsRNA, dsRNA, and mock/injected with buffer) selected for microarray analysis were free of pre-existing conditions (assessed by APM analysis) (Runckel, Flenniken et al., 2011). To facilitate gene expression comparisons between multiple treatment groups we utilized a reference-design strategy in which each Cy5-labeled experimental sample was hybridized with a standardized Cy3-labeled reference sample. A complex RNA mixture representing hundreds of bees of various ages exposed to difference treatment groups, served as the reference RNA sample.