Reference Transcriptome for a Facultatively Eusocial Bee, Megalopta genalis

This article analyses gendering processes in two distinct models of work organization. It is a widespread belief that, compared to hierarchical (Tayloristic) organizations, team-based work offers opportunities for a high quality of working life to a broader range of employees, both men and women. Our research, however, suggests that gender inequality is (re)produced in both settings and results from the so-called gender subtext. The gender subtext is the set of often concealed power-based processes (re)producing gender distinction in social practices through organizational and individual arrangements. We draw a comparison between the gender subtext of Tayloristic and team-based work organizations through a theoretical analysis, illustrated by empirical data concerning the functioning of the gender subtext in organizations in the Dutch banking sector. Taylorism and team-based work differ in their conceptualization of organization and job design, but, when it comes to the gender subtext, it is six of one and half a dozen of the other. We argue that in both approaches a gender subtext contributes to the emergence of different but gendered notions of the ‘disembodied worker’. In both cases the notion of the abstract worker is implicitly loaded with masculine connotations. This gender bias is supported by two factors influencing the gendering of jobs: the gender connotations of care responsibilities and of qualification profiles. These implicit connotations produce and reinforce unequal opportunities for men and women to get highly qualified or management jobs. Our research, therefore, questions the self-evidence of stating that team-based work will offer opportunities for a higher quality of working life for women

Brain microRNAs among social and solitary bees

Evolutionary transitions to a social lifestyle in insects are associated with lineage-specific changes in gene expression, but the key nodes that drive these regulatory changes are unknown. We examined the relationship between social organization and lineage-specific microRNAs (miRNAs). Genome scans across 12 bee species showed that miRNA copy-number is mostly conserved and not associated with sociality. However, deep sequencing of small RNAs in six bee species revealed a substantial proportion (20–35%) of detected miRNAs had lineage-specific expression in the brain, 24–72% of which did not have homologues in other species. Lineage-specific miRNAs disproportionately target lineage-specific genes, and have lower expression levels than shared miRNAs. The predicted targets of lineage-specific miRNAs are not enriched for genes with caste-biased expression or genes under positive selection in social species. Together, these results suggest that novel miRNAs may coevolve with novel genes, and thus contribute to lineage-specific patterns of evolution in bees, but do not appear to have significant influence on social evolution. Our analyses also support the hypothesis that many new miRNAs are purged by selection due to deleterious effects on mRNA targets, and suggest genome structure is not as influential in regulating bee miRNA evolution as has been shown for mammalian miRNAs

Developmental plasticity shapes social traits and selection in a facultatively eusocial bee

Developmental plasticity generates phenotypic variation, but how it contributes to evolutionary change is unclear. Phenotypes of individuals in caste-based (eusocial) societies are particularly sensitive to developmental processes, and the evolutionary origins of eusociality may be rooted in developmental plasticity of ancestral forms. We used an integrative genomics approach to evaluate the relationships among developmental plasticity, molecular evolution, and social behavior in a bee species (Megalopta genalis) that expresses flexible sociality, and thus provides a window into the factors that may have been important at the evolutionary origins of eusociality. We find that differences in social behavior are derived from genes that also regulate sex differentiation and metamorphosis. Positive selection on social traits is influenced by the function of these genes in development. We further identify evidence that social polyphenisms may become encoded in the genome via genetic changes in regulatory regions, specifically in transcription factor binding sites. Taken together, our results provide evidence that developmental plasticity provides the substrate for evolutionary novelty and shapes the selective landscape for molecular evolution in a major evolutionary innovation: Eusociality

Genomic epidemiology of a protracted hospital outbreak caused by multidrug-resistant Acinetobacter baumannii in Birmingham, England

BACKGROUND: Multidrug-resistant Acinetobacter baumannii commonly causes hospital outbreaks. However, within an outbreak, it can be difficult to identify the routes of cross-infection rapidly and accurately enough to inform infection control. Here, we describe a protracted hospital outbreak of multidrug-resistant A. baumannii, in which whole-genome sequencing (WGS) was used to obtain a high-resolution view of the relationships between isolates. METHODS: To delineate and investigate the outbreak, we attempted to genome-sequence 114 isolates that had been assigned to the A. baumannii complex by the Vitek2 system and obtained informative draft genome sequences from 102 of them. Genomes were mapped against an outbreak reference sequence to identify single nucleotide variants (SNVs). RESULTS: We found that the pulsotype 27 outbreak strain was distinct from all other genome-sequenced strains. Seventy-four isolates from 49 patients could be assigned to the pulsotype 27 outbreak on the basis of genomic similarity, while WGS allowed 18 isolates to be ruled out of the outbreak. Among the pulsotype 27 outbreak isolates, we identified 31 SNVs and seven major genotypic clusters. In two patients, we documented within-host diversity, including mixtures of unrelated strains and within-strain clouds of SNV diversity. By combining WGS and epidemiological data, we reconstructed potential transmission events that linked all but 10 of the patients and confirmed links between clinical and environmental isolates. Identification of a contaminated bed and a burns theatre as sources of transmission led to enhanced environmental decontamination procedures. CONCLUSIONS: WGS is now poised to make an impact on hospital infection prevention and control, delivering cost-effective identification of routes of infection within a clinically relevant timeframe and allowing infection control teams to track, and even prevent, the spread of drug-resistant hospital pathogens

Reproductive plasticity and the evolution of the insect societies

A fundamental goal of evolutionary biology is to understand how novel traits arise. Eusociality represents an extreme form of social organization which has evolved independently a number of times across insects and is characterized especially in the Hymenoptera by a novel polyphenism between reproductive (queen) and non-reproductive (worker) castes. While a growing body of research continues to improve our understanding of the mechanisms underlying the development of these castes, less is known about how castes evolved from solitary ancestors. In this dissertation, I leverage naturally-occurring social plasticity in two species of bees to shed light on potential mechanisms of caste evolution across social insects. In Chapter 1, I provide a detailed overview of the work contained within this dissertation. In Chapter 2, I develop a perspective on how ancestral behavioral plasticity may have facilitated the evolution of castes through genetic accommodation. In Chapter 3, I present a de novo transcriptome assembly for Megalopta genalis, a facultatively eusocial sweat bee that exhibits multiple social phenotypes within one population and may therefore represent a transition between solitary and social reproduction. I use this transcriptome in Chapter 4 to identify gene expression differences associated with social phenotypes of M. genalis, and compare these to genes involved in caste determination of other eusocial species as well as genes implicated in the evolution of eusociality through comparative studies of bees. In Chapter 5, I use a high-resolution behavioral tracking system to discover a previously undescribed form of colony organization in honey bees that occurs after a colony loses and is unable to replace its queen and some workers begin to lay eggs. Surprisingly similar to the social variation observed across nests of M. genalis, these colonies of honey bee workers display multiple levels of social plasticity, evoking transitional stages in eusocial evolution associated with the venerable Ovarian Ground Plan Hypothesis. Finally, in Chapter 6, I use transcriptomics and chromatin accessibility analyses of bees in laying worker colonies to explore how changes in brain gene regulation may contribute to variation in colony social organization, with comparative analyses to place this variation in the broader context of caste evolution across social insect lineages.LimitedAuthor requested closed access (OA after 2yrs) in Vireo ETD syste

Data from: Transcriptional markers of sub-optimal nutrition in developing Apis mellifera nurse workers

Background: Honey bees (Apis mellifera) contribute substantially to the worldwide economy and ecosystem health as pollinators. Pollen is essential to the bee’s diet, providing protein, lipids, and micronutrients. The dramatic shifts in physiology, anatomy, and behavior that accompany normal worker development are highly plastic and recent work demonstrates that development, particularly the transition from nurse to foraging roles, is greatly impacted by diet. However, the role that diet plays in the developmental transition of newly eclosed bees to nurse workers is poorly understood. To further understand honey bee nutrition and the role of diet in nurse development, we used a high-throughput screen of the transcriptome of 3 day and 8 day old worker bees fed either honey and stored pollen (rich diet) or honey alone (poor diet) within the hive. We employed a three factor (age, diet, age x diet) analysis of the transcriptome to determine whether diet affected nurse worker physiology and whether poor diet altered the developmental processes normally associated with aging. Results: Substantial changes in gene expression occurred due to starvation. Diet-induced changes in gene transcription occurring in younger bees were largely a subset of those occurring in older bees, but certain signatures of starvation were only evident 8 day old workers. Of the 18,542 annotated genes in the A. mellifera genome, 0.7% (126 genes) exhibited differential expression due to poor diet at 3d of age compared with 81% (15,001 genes) that differed due to poor diet at 8d of age. Of the genes that were differentially expressed in young or old pollen deprived bees, poor diet caused more frequent down-regulation of gene expression in younger bees compared to older bees. In addition, the age-related physiological changes that accompanied early adult development differed due to the diet these young adult bees were fed. More frequent down-regulation of gene expression was observed in developing bees fed a poor diet compared to an adequate diet. Functional analyses also show that the physiological and developmental processes occurring in well-fed bees are vastly different than those occurring in pollen deprived bees. These data support the hypothesis that poor diet causes normal age-related development to go awry. Conclusion: Poor nutrition has major consequences for the expression of genes underlying the physiology and age-related development of nurse worker bees. More work is certainly needed to fully understand the consequences of starvation and the complex biology of nutrition and development in this system, but the genes identified in the present study provide a starting point for understanding the consequences of poor diet and for mitigating the economic costs of colony starvation

Putative orthologs and conversion lists from Caste-biased gene expression in a facultatively eusocial bee suggests a role for genetic accommodation in the evolution of eusociality

BLAST reciprocal best hit results between <i>Megalopta genalis</i> and <i>Apis mellifera</i>, as well as between <i>M. genalis</i> and <i>Bombus terrestris</i>. Conversion lists used to translate between two <i>A. mellifera</i> microarrays, an older (OGSv2.0) and current (OGSv3.2) annotation of the honey bee genome are also provided