Transcription profiling by array of honey bee workers orally exposed to two different pesticides (coumaphos, fluvalinate)
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ABSTRACT: We explored the impact of coumaphos and fluvalinate, the two most abundant and frequently detected pesticides in the hive, on genome-wide gene expression patterns of honey bee workers. We found significant changes in 1118 transcripts, including genes involved in detoxification, behavioral maturation, immunity, and nutrition. Our results demonstrate that pesticide exposure can substantially impact expression of genes involved in several core physiological pathways in honey bee workers.
Project description:Newly emerged adult workers (24 hours old) were infected with 25,000 Nosema apis spores and 25,000 Nosema ceranae spores in sucrose solution. Controls were fed sucrose. Workers were maintained in cages in an incubator and collected at 14 days post-infection. Fat bodies (eviscerated abdomens) were dissected and whole genome expression in this tissue was compared across treatments using microarrays.
Project description:Newly emerged adult workers (24 hours old) were infected with 50,000 Nosema apis spores in sucrose solution. Controls were fed sucrose. Workers were maintained in cages in an incubator and collected at 2 and 7 days post-infection. Fat body tissue was dissected (eviscerated abdomen) and whole genome expression in this tissue was compared across treatments and collection time points using microarrays.
Project description:Newly emerged adult workers (24 hours old) were infected with 50,000 Nosema apis spores in sucrose solution. Controls were fed sucrose. Workers were maintained in cages in an incubator and collected at 1 and 2 days post-infection. Midguts were dissected and whole genome expression in this tissue was compared across treatments and collection time points using microarrays.
Project description:Here, we examined the transcriptional and epigenetic (DNA methylation) responses to viral infection in honey bee workers. One-day old worker honey bees were fed solutions containing Israeli Acute Paralysis Virus (IAPV), a virus which causes muscle paralysis and death and has previously been associated with colony loss. Uninfected control and infected, symptomatic bees were collected within 20-24 hours after infection. Worker fat bodies, the primary tissue involved in metabolism, detoxification and immune responses, were collected for analysis. We performed transcriptome- and bisulfite-sequencing of the worker fat bodies to identify genome-wide gene expression and DNA methylation patterns associated with viral infection. There were 753 differentially expressed genes (FDR<0.05) in infected versus control bees, including several genes involved in epigenetic and antiviral pathways. DNA methylation status of 156 genes (FDR<0.1) changed significantly as a result of the infection, including those involved in antiviral responses in humans. There was no significant overlap between the significantly differentially expressed and significantly differentially methylated genes, and indeed, the genomic characteristics of these sets of genes were quite distinct. Our results indicate that honey bees have two distinct molecular pathways, mediated by transcription and methylation, that modulate protein levels and/or function in response to viral infections. Examination of epigenomic and transcriptomic antiviral responses to Israeli Acute Paralysis Virus in honey bees
Project description:Honey bees move through a series of in-hive tasks (M-bM-^@M-^\nursingM-bM-^@M-^]) to outside tasks (M-bM-^@M-^\foragingM-bM-^@M-^]) that coincident with an intense increase in metabolic activity. Social context can cause worker bees to speed up, or slow down this process and foragers may revert back to their earlier in hive tasks accompanied by reversion to earlier physiological states. To determine if the transcriptional profile of forager bees can revert, or if the effects of flight on gene expression are irreversible, we used whole-genome microarrays. Brain tissue and flight muscle exhibited independent patterns of expression during behavioral transitions, with patterns of expression in the brain reflecting both age and behavior, while flight muscle exhibited primarily age-related patterns of expression. Our data suggest that the transition from little to no flight (nurse) to intense flight (forager), rather than the amount of flight has a major effect on gene expression. Following behavioral reversion there was a partial reversion in gene expression but some aspects of forager expression patterns, such as those for genes involved in immune function, remained. These data suggest an epigenetic control and energy balance role in honey bee functional senescence. Brains and thoraces from the same individuals of all behavioral groups were compared on a total of 132 arrays. The samples were hybridized against each other using a loop design. The groups tested are outlined as follows: Typical aged nurse 'YN' (8-10 days old; <1 day flight experience), Precocious forager 'PF' (8 to 10 days old; 2 to 3 days flight experience), Overaged nurse 'ON' (19 to 22 days old; < 1 day flight experience), Forager - low flight 'TFL' (19 to 22 days old; 2 to 3 days flight experience), Forager - high flight 'TFH' ( 19 to 22 days old; 7 to 9 days flight experience), Forager - old 'OF' (25 to 26 days old; 10 to 12 days flight experience), Reverted nurse 'RN' (25 to 26 days old; 7 to 9 days flight experience). The comparisons are outlined as follows: YN:ON (6 arrays), ON:RN (6 arrays), RN:TFH (6 arrays), TFH:TFL (6 arrays), TFL:PF (6 arrays), PF:YN (6 arrays), ON:TFL (12 arrays), YN:OF (6 arrays), OF:RN (6 arrays), RN:YN (6 arrays). Each comparison was done for individual brains and thoraces. Total: 132 arrays
Project description:Mating causes dramatic changes in female insects at the behavioral, physiological, and molecular levels. The factors driving these changes (e.g., seminal proteins, seminal volume) and the molecular pathways by which these factors are operating have been characterized only in a handful of insect species. Here we use instrumental insemination of honey bee queens to examine the role of the insemination substance (saline vs. semen) and volume (1 vs. 8 uL) in triggering post-mating changes. We also examine differences in gene expression patterns in the fat bodies of queens that have high ovary activation to determine if events during copulation can cause long-term changes in gene expression. We found that the instrumental insemination procedure alone caused cessation of mating flights and triggered ovary activation, with insemination volume contributing to increased ovary activation. Hierarchical clustering grouped queens primarily by insemination substance and then insemination volume, suggesting that while volume may trigger short-term physiological changes, substance plays a greater role in regulating long-term transcriptional changes. There was considerable but not a complete overlap in the gene pathways regulated by these two factors. Comparisons with gene lists from previous studies on queen mating revealed that several of the same biological processes and pathways were regulated, but only one gene (defensin) was found to be regulated in all studies. Our results suggest that both insemination substance and volume trigger molecular post-mating changes by altering overlapping gene pathways involved in honey bee reproduction.
Project description:BACKGROUND: Social insects, such as honey bees, use molecular, physiological and behavioral responses to combat pathogens and parasites. The honey bee genome contains all of the canonical insect immune response pathways, and several studies have demonstrated that pathogens can activate expression of immune effectors. Honey bees also use behavioral responses, termed social immunity, to collectively defend their hives from pathogens and parasites. These responses include hygienic behavior (where workers remove diseased brood) and allo-grooming (where workers remove ectoparasites from nestmates). We have previously demonstrated that immunostimulation causes changes in the cuticular hydrocarbon profiles of workers, which results in altered worker-worker social interactions. Thus, cuticular hydrocarbons may enable workers to identify sick nestmates, and adjust their behavior in response. Here, we test the specificity of behavioral, chemical and genomic responses to immunostimulation by challenging workers with a panel of different immune stimulants (saline, Sephadex beads and Gram-negative bacteria E. coli). RESULTS: While only bacteria-injected bees elicited altered behavioral responses from healthy nestmates compared to controls, all treatments resulted in significant changes in cuticular hydrocarbon profiles. Immunostimulation caused significant changes in expression of hundreds of genes, the majority of which have not been identified as members of the canonical immune response pathways. Furthermore, several new candidate genes that may play a role in cuticular hydrocarbon biosynthesis were identified. Finally, we identified common genes regulated by pathogen challenge in honey bees and other insects, suggesting that immune responses are conserved at the molecular level. CONCLUSIONS: These studies suggest that honey bee genomic responses to immunostimulation are substantially broader than expected, and may mediate the behavioral changes associated with social immunity by orchestrating changes in chemical signaling.
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:In honey bees (Apis mellifera), the reproductive queen produces a pheromonal signal that regulates many aspects of worker behavior and physiology and is critical for maintaining colony organization. Queen mandibular pheromone (QMP) inhibits worker reproduction, attracts workers from a short distance (retinue response), inhibits the rearing of new queens, modulates age-related division of labor and globally alters brain gene expression in worker bees. Interestingly, substantial variation in worker retinue responses to QMP has been found between colonies, but the molecular and physiological bases for variation in individual responses to the queen have not been characterized. Here, we demonstrate that individual retinue response is negatively correlated with traits associated with reproductive potential. Workers with low response to QMP have more ovarioles and higher levels of vitellogenin transcripts than workers with a high response to QMP, suggesting that workers with greater reproductive potential may be attempting to escape queen control. Retinue response appears to be associated with a suite of behavioral and physiological traits that may be pleiotropically linked. However, while these phenotypes are all correlated at the organismal level, the underlying brain expression patterns and gene networks associated with each trait are independent, suggesting that these phenotypes are uncoupled at the molecular level in adult bees. These studies provide insights into the ultimate and proximate causes of natural variation in pheromone response in honey bees.