Unique features of a global human ectoparasite identified through sequencing of the bed bug genome

The bed bug, Cimex lectularius, has re-established itself as a ubiquitous human ectoparasite throughout much of the world during the past two decades. This global resurgence is likely linked to increased international travel and commerce in addition to widespread insecticide resistance. Analyses of the C. lectularius sequenced genome (650 Mb) and 14,220 predicted protein-coding genes provide a comprehensive representation of genes that are linked to traumatic insemination, a reduced chemosensory repertoire of genes related to obligate hematophagy, host–symbiont interactions, and several mechanisms of insecticide resistance. In addition, we document the presence of multiple putative lateral gene transfer events. Genome sequencing and annotation establish a solid foundation for future research on mechanisms of insecticide resistance, human–bed bug and symbiont–bed bug associations, and unique features of bed bug biology that contribute to the unprecedented success of C. lectularius as a human ectoparasite

The genome of the water strider Gerris buenoi reveals expansions of gene repertoires associated with adaptations to life on the water.

BACKGROUND: Having conquered water surfaces worldwide, the semi-aquatic bugs occupy ponds, streams, lakes, mangroves, and even open oceans. The diversity of this group has inspired a range of scientific studies from ecology and evolution to developmental genetics and hydrodynamics of fluid locomotion. However, the lack of a representative water strider genome hinders our ability to more thoroughly investigate the molecular mechanisms underlying the processes of adaptation and diversification within this group. RESULTS: Here we report the sequencing and manual annotation of the Gerris buenoi (G. buenoi) genome; the first water strider genome to be sequenced thus far. The size of the G. buenoi genome is approximately 1,000 Mb, and this sequencing effort has recovered 20,949 predicted protein-coding genes. Manual annotation uncovered a number of local (tandem and proximal) gene duplications and expansions of gene families known for their importance in a variety of processes associated with morphological and physiological adaptations to a water surface lifestyle. These expansions may affect key processes associated with growth, vision, desiccation resistance, detoxification, olfaction and epigenetic regulation. Strikingly, the G. buenoi genome contains three insulin receptors, suggesting key changes in the rewiring and function of the insulin pathway. Other genomic changes affecting with opsin genes may be associated with wavelength sensitivity shifts in opsins, which is likely to be key in facilitating specific adaptations in vision for diverse water habitats. CONCLUSIONS: Our findings suggest that local gene duplications might have played an important role during the evolution of water striders. Along with these findings, the sequencing of the G. buenoi genome now provides us the opportunity to pursue exciting research opportunities to further understand the genomic underpinnings of traits associated with the extreme body plan and life history of water striders

The genome of the water strider Gerris buenoi reveals expansions of gene repertoires associated with adaptations to life on the water

Background: Having conquered water surfaces worldwide, the semi-aquatic bugs occupy ponds, streams, lakes, mangroves, and even open oceans. The diversity of this group has inspired a range of scientific studies from ecology and evolution to developmental genetics and hydrodynamics of fluid locomotion. However, the lack of a representative water strider genome hinders our ability to more thoroughly investigate the molecular mechanisms underlying the processes of adaptation and diversification within this group. Results: Here we report the sequencing and manual annotation of the Gerris buenoi (G. buenoi) genome; the first water strider genome to be sequenced thus far. The size of the G. buenoi genome is approximately 1,000Mb, and this sequencing effort has recovered 20,949 predicted protein-coding genes. Manual annotation uncovered a number of local (tandem and proximal) gene duplications and expansions of gene families known for their importance in a variety of processes associated with morphological and physiological adaptations to a water surface lifestyle. These expansions may affect key processes associated with growth, vision, desiccation resistance, detoxification, olfaction and epigenetic regulation. Strikingly, the G. buenoi genome contains three insulin receptors, suggesting key changes in the rewiring and function of the insulin pathway. Other genomic changes affecting with opsin genes may be associated with wavelength sensitivity shifts in opsins, which is likely to be key in facilitating specific adaptations in vision for diverse water habitats. Conclusions: Our findings suggest that local gene duplications might have played an important role during the evolution of water striders. Along with these findings, the sequencing of the G. buenoi genome now provides us the opportunity to pursue exciting research opportunities to further understand the genomic underpinnings of traits associated with the extreme body plan and life history of water striders

Les gènes Hox et l'évolution des phénotypes adaptatives

Les populations sont soumises à des pressions sélectives qui agissent sur certains traits entraînant une divergence phénotypique. L'évolution des morphologies adaptatives est souvent liée avec des changements de structures préexistantes. Les insectes semi-Aquatiques ont subi une croissance de pattes exagérée qui est associée à leur adaptation et locomotion efficace à la surface de l'eau. Cette croissance excessive a facilitée l'exploitation de l'habitat aquatique restreint pour les espèces terrestres apparentées. En outre, le groupe dérivé des gerris a subi des modifications supplémentaires au niveau des pattes, de sorte que la deuxième patte (P2) est plus longue que la troisième patte (P3). Ce plan d'organisation inversé par rapport à celui des espèces terrestres, est associé à la spécialisation pour une vie sur l'eau. Les gerris ont acquis un mode de locomotion dérivée qui consiste à ramer par des mouvements simultanés de leurs P2 et des mouvements plus subtils de leurs P3 pour s'orienter. La structure et la croissance des pattes des insectes semi-Aquatiques sont réalisées durant l'embryogenèse. En effet, la nymphe qui éclot possède des pattes fonctionnelles. Il a été démontré que le facteur de transcription Hox, Ubx, est impliqué dans cette inversion du plan des pattes. Cependant, les mécanismes génétiques responsables de ces adaptations restent toujours obscurs. La thèse présentée examine ces questions à travers deux axes : premièrement, déterminer les gènes et les voies de signalisation responsables du développement et de la croissance remarquable des pattes ; deuxièmement, étudier le rôle du gène Hox impliqué dans l'inversion du plan des pattes caractéristique des gerrisPopulations are faced with selective pressures that act on certain traits resulting in phenotypic divergence. The evolution of adaptive morphological traits is often associated with changes in pre-Existing structures. In semiaquatic insects, a dramatic growth of thoracic appendages is associated with their adaptation and efficient locomotion on the water surface. This particular leg allometry facilitated the exploitation of aquatic habitats, a restricted niche for their terrestrial relatives; and hence opens a new array of ecological opportunities. Additionally, the derived group of water striders has undergone further appendage modification, such that T2-Legs are longer than T3-Legs, a ground plan associated with the specialization to open water. Water striders have evolved a derived mode of locomotion through rowing on water. They move their mid-Legs in simultaneous sweeping strokes for propulsion, and move their hind-Legs in fine movements for orientation. Leg specification and elongation in semiaquatic insects happens during early embryogenesis as the newly hatching nymphs emerge with functional legs. The Hox transcription factor Ubx was found to be implicated in the reversal in leg ground plan. Nonetheless, the genetic mechanisms underlying these leg adaptive changes are still poorly understood. The presented thesis investigates these questions through two main goals: first, to uncover the genes and pathways implicated in the development and dramatic elongation of the legs; second, to examine the dynamics of Hox control responsible for the reversal in leg ground plan characteristic of water strider

Les gènes Hox et l'évolution des phénotypes adaptatives

Populations are faced with selective pressures that act on certain traits resulting in phenotypic divergence. The evolution of adaptive morphological traits is often associated with changes in pre-Existing structures. In semiaquatic insects, a dramatic growth of thoracic appendages is associated with their adaptation and efficient locomotion on the water surface. This particular leg allometry facilitated the exploitation of aquatic habitats, a restricted niche for their terrestrial relatives; and hence opens a new array of ecological opportunities. Additionally, the derived group of water striders has undergone further appendage modification, such that T2-Legs are longer than T3-Legs, a ground plan associated with the specialization to open water. Water striders have evolved a derived mode of locomotion through rowing on water. They move their mid-Legs in simultaneous sweeping strokes for propulsion, and move their hind-Legs in fine movements for orientation. Leg specification and elongation in semiaquatic insects happens during early embryogenesis as the newly hatching nymphs emerge with functional legs. The Hox transcription factor Ubx was found to be implicated in the reversal in leg ground plan. Nonetheless, the genetic mechanisms underlying these leg adaptive changes are still poorly understood. The presented thesis investigates these questions through two main goals: first, to uncover the genes and pathways implicated in the development and dramatic elongation of the legs; second, to examine the dynamics of Hox control responsible for the reversal in leg ground plan characteristic of water stridersLes populations sont soumises à des pressions sélectives qui agissent sur certains traits entraînant une divergence phénotypique. L'évolution des morphologies adaptatives est souvent liée avec des changements de structures préexistantes. Les insectes semi-Aquatiques ont subi une croissance de pattes exagérée qui est associée à leur adaptation et locomotion efficace à la surface de l'eau. Cette croissance excessive a facilitée l'exploitation de l'habitat aquatique restreint pour les espèces terrestres apparentées. En outre, le groupe dérivé des gerris a subi des modifications supplémentaires au niveau des pattes, de sorte que la deuxième patte (P2) est plus longue que la troisième patte (P3). Ce plan d'organisation inversé par rapport à celui des espèces terrestres, est associé à la spécialisation pour une vie sur l'eau. Les gerris ont acquis un mode de locomotion dérivée qui consiste à ramer par des mouvements simultanés de leurs P2 et des mouvements plus subtils de leurs P3 pour s'orienter. La structure et la croissance des pattes des insectes semi-Aquatiques sont réalisées durant l'embryogenèse. En effet, la nymphe qui éclot possède des pattes fonctionnelles. Il a été démontré que le facteur de transcription Hox, Ubx, est impliqué dans cette inversion du plan des pattes. Cependant, les mécanismes génétiques responsables de ces adaptations restent toujours obscurs. La thèse présentée examine ces questions à travers deux axes : premièrement, déterminer les gènes et les voies de signalisation responsables du développement et de la croissance remarquable des pattes ; deuxièmement, étudier le rôle du gène Hox impliqué dans l'inversion du plan des pattes caractéristique des gerri

Unique features of a global human ectoparasite identified through sequencing of the bed bug genome

The bed bug, Cimex lectularius, has re-established itself as a ubiquitous human ectoparasite throughout much of the world during the past two decades. This global resurgence is likely linked to increased international travel and commerce in addition to widespread insecticide resistance. Analyses of the C. lectularius sequenced genome (650 Mb) and 14,220 predicted protein-coding genes provide a comprehensive representation of genes that are linked to traumatic insemination, a reduced chemosensory repertoire of genes related to obligate hematophagy, host-symbiont interactions, and several mechanisms of insecticide resistance. In addition, we document the presence of multiple putative lateral gene transfer events. Genome sequencing and annotation establish a solid foundation for future research on mechanisms of insecticide resistance, human-bed bug and symbiont-bed bug associations, and unique features of bed bug biology that contribute to the unprecedented success of C. lectularius as a human ectoparasite