We report here genome sequences and comparative analyses of three closely related parasitoid wasps: Nasonia vitripennis, N. giraulti, and N. longicornis. Parasitoids are important regulators of arthropod populations, including major agricultural pests and disease vectors, and Nasonia is an emerging genetic model, particularly for evolutionary and developmental genetics. Key findings include the identification of a functional DNA methylation tool kit; hymenopteran-specific genes including diverse venoms; lateral gene transfers among Pox viruses, Wolbachia, and Nasonia; and the rapid evolution of genes involved in nuclear-mitochondrial interactions that are implicated in speciation. Newly developed genome resources advance Nasonia for genetic research, accelerate mapping and cloning of quantitative trait loci, and will ultimately provide tools and knowledge for further increasing the utility of parasitoids as pest insect-control agents.

Here we report the genome sequence of the honeybee Apis mellifera, a key model for social behaviour and essential to global ecology through pollination. Compared with other sequenced insect genomes, the A. mellifera genome has high A+T and CpG contents, lacks major transposon families, evolves more slowly, and is more similar to vertebrates for circadian rhythm, RNA interference and DNA methylation genes, among others. Furthermore, A. mellifera has fewer genes for innate immunity, detoxification enzymes, cuticle-forming proteins and gustatory receptors, more genes for odorant receptors, and novel genes for nectar and pollen utilization, consistent with its ecology and social organization. Compared to Drosophila, genes in early developmental pathways differ in Apis, whereas similarities exist for functions that differ markedly, such as sex determination, brain function and behaviour. Population genetics suggests a novel African origin for the species A. mellifera and insights into whether Africanized bees spread throughout the New World via hybridization or displacement.

BackgroundThe shift from solitary to social behavior is one of the major evolutionary transitions. Primitively eusocial bumblebees are uniquely placed to illuminate the evolution of highly eusocial insect societies. Bumblebees are also invaluable natural and agricultural pollinators, and there is widespread concern over recent population declines in some species. High-quality genomic data will inform key aspects of bumblebee biology, including susceptibility to implicated population viability threats.ResultsWe report the high quality draft genome sequences of Bombus terrestris and Bombus impatiens, two ecologically dominant bumblebees and widely utilized study species. Comparing these new genomes to those of the highly eusocial honeybee Apis mellifera and other Hymenoptera, we identify deeply conserved similarities, as well as novelties key to the biology of these organisms. Some honeybee genome features thought to underpin advanced eusociality are also present in bumblebees, indicating an earlier evolution in the bee lineage. Xenobiotic detoxification and immune genes are similarly depauperate in bumblebees and honeybees, and multiple categories of genes linked to social organization, including development and behavior, show high conservation. Key differences identified include a bias in bumblebee chemoreception towards gustation from olfaction, and striking differences in microRNAs, potentially responsible for gene regulation underlying social and other traits.ConclusionsThese two bumblebee genomes provide a foundation for post-genomic research on these key pollinators and insect societies. Overall, gene repertoires suggest that the route to advanced eusociality in bees was mediated by many small changes in many genes and processes, and not by notable expansion or depauperation.Electronic supplementary materialThe online version of this article (doi:10.1186/s13059-015-0623-3) contains supplementary material, which is available to authorized users.

The Wnt protein Wingless (Wg) functions as a signal in patterning of both the Drosophila embryo and imaginal discs. Lack of porcupine ~7orc) activity is associated with mutant phenotypes similar to those of wg mutations. In porc mutant embryos, Wg protein is confined to the cells that produce it, suggesting that Porc plays a role in processing or secretion of Wg. porc encodes a novel transmembrane protein that appears to be concentrated at the endoplasmic reticulum. We present both genetic and in vitro evidence demonstrating that porc is involved specifically in the processing of Wg. We identified a human sequence related to Porc suggesting the existence of a family of proteins involved in processing of Wnts.[Key Words: Drosophila; transmembrane protein; Wingless; porcupine]Received October 1, 1996; revised version accepted October 30, 1996.Like its murine homolog, the proto-oncogene Wnt-1, Drosophila wingless {wgl encodes a secreted protein that has potent effects on the differentiation of responsive cells (for review see, Klingensmith and Nusse 1994; Siegfried and Perrimon 1994}. Wg has been implicated in a number of developmental processes that include embryonic segmentation, gut formation, and imaginal discs patteming. To identify components involved in Wg signaling, a genetic approach has been undertaken. To date, four segment polarity genes, dishevelled {dsh), armadillo (arm), zeste-white3 (zw3), and porcupine (porc) have been implicated in Wg signaling. The current model (for review, see Bhanot et al. 1996;Perrimon 1996) is that Wg, which requires Pore activity to be secreted, interacts with the seven-transmembrane DFz2 receptor to activate a signal transduction pathway that is mediated by Dsh, Zw3, and Arm. This pathway operates in a number of developmental processes and, depending on the cell type, regulates different sets of transcription factors. For example, Wg signaling regulates engrafted (en) in the embryonic epidermis and genes of the achaete scute complex at the wing margin.The function of Pore in Wg signaling is not elucidated. Embryos that are missing both the maternal and zygotic pore gene product have a cuticular phenotype identical to wg mutant embryos {Perrimon et al. 19891. Interestingly, Wg has an altered, less diffuse distribution in pore mutant embryos. In wild-type animals, expression studies have shown that Wg protein is found outside its RNA expression domain. In the embryonic epidermis, Wg protein antibody staining appears punctate because of the accumulation of Wg in intracellular vesicles. These vesicles are detected both in wg-expressing and neighboring wg nonexpressing cells, and the distribution of these vesicles appears graded on either side of the wg-expressing cells {van den Heuvel et al. 1989;Gonzalez et al. 1991;Couso et al. 1994}. In pore mutant animals, Wg appears to be confined to the expressing cells, and is very stable {van den Heuvel et al. 1993; Siegfried et al. 19941, sug-gesting that pore encodes a product required for secretion, processing or normal diffusion of...

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Abstract. To understand the mechanisms of mRNA transport in eukaryotes, we have isolated Saccharomyces cerevisiae temperature-sensitive (ts) mutants which accumulate poly(A) + RNA ha the nucleus at the restrictive temperature. A total of 21 recessive mutants were isolated and classified into 16 complementation groups. Backcrossed mRNA transportdefective strains from each complementation group have been analyzed. A strain which is ts for heat shock transcription factor was also analyzed since it also shows nuclear accumulation of poly(A) + RNA at 37°C. At 37°C the mRNA of each mutant is characterized by atypically long polyA tails. Unlike ts pre-mRNA splithag mutants, these strains do not interrupt splicing of pre-mRNA at 370C; however four strains accumulate oversized RNA polymerase II transcripts. Some show inhibition of rRNA processing and a further subset of these strains is also characterized by inhibition of tRNA maturation. Several strains accumulate nuclear proteins ha the cytoplasm when incubated at semipermissive temperature. Remarkably, many strains exhibit nucleolar fragmentation or enlargement at the restrictive temperature. Most strains show dramatic ultrastructural alterations of the nucleoplasm or nuclear membrane. Distinct mutants accumulate poly(A) + RNA in characteristic patterns ha the nucleus.

The current insect genome sequencing projects provide an opportunity to extend studies of the evolution of developmental genes and pathways in insects. In this paper we examine the conservation and divergence of genes and developmental processes between Drosophila and the honey bee; two holometabolous insects whose lineages separated ∼300 million years ago, by comparing the presence or absence of 308 Drosophila developmental genes in the honey bee. Through examination of the presence or absence of genes involved in conserved pathways (cell signaling, axis formation, segmentation and homeobox transcription factors), we find that the vast majority of genes are conserved. Some genes involved in these processes are, however, missing in the honey bee. We have also examined the orthology of Drosophila genes involved in processes that differ between the honey bee and Drosophila. Many of these genes are preserved in the honey bee despite the process in which they act in Drosophila being different or absent in the honey bee. Many of the missing genes in both situations appear to have arisen recently in the Drosophila lineage, have single known functions in Drosophila, and act early in developmental pathways, while those that are preserved have pleiotropic functions. An evolutionary interpretation of these data is that either genes with multiple functions in a common ancestor are more likely to be preserved in both insect lineages, or genes that are preserved throughout evolution are more likely to co-opt additional functions.

Wnt is a family of cysteine-rich secreted glycoproteins, which controls the fate and behavior of the cells in multicellular organisms. In the absence of Drosophila segment polarity gene porcupine (porc), which encodes an endoplasmic reticulum (ER) multispanning transmembrane protein, the N-glycosylation of Wingless (Wg), one of Drosophila Wnt family, is impaired. In contrast, the ectopic expression of porc stimulates the Nglycosylation of both endogenously and exogenously expressed Wg. The N-glycosylation of Wg in the ER occurs posttranslationally, while in the presence of dithiothreitol, it efficiently occurs cotranslationally. Thus, the cotranslational disulfide bond formation of Wg competes with the N-glycosylation by an oligosaccharyl transferase complex. Porc binds the N-terminal 24-amino acid domain (residues 83-106) of Wg, which is highly conserved in the Wnt family and stimulates the N-glycosylation at surrounding sites. Porc is also necessary for the processing of Drosophila Wnt-3/5 in both embryos and cultured cells. Thus, Porc binds the N-terminal specific domain of the Wnt family and stimulates its posttranslational N-glycosylation by anchoring them at the ER membrane possibly through acylation.