The genomes of two key bumblebee species with primitive eusocial organization

Background: The 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. Results: We 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. Conclusions: These 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

The influence of cortical perforations and of space filling with peripheral blood on the kinetics of guided bone generation. A comparative histometric study in the rat.

The aim of the present study was to evaluate the influence of cortical perforations and of peripheral blood addition in guided bone generation beyond the skeletal envelope in rats. A total of 30 isogenic adult rats were divided into 3 equal groups. In each rat, two hollow parallelipipedic titanium chambers were placed bilaterally on the calvaria after a periosteal skin flap was raised. While on the right sides (controls) the osseous surface was left intact and the chambers were empty, the cortical bone under the left-side chambers (test sites) was perforated with nine 0.8 mm-diameter holes (group I), or left intact but with the chambers filled with a clot of peripheral blood (group II). In group III, both procedures were combined in the test sites. The healing was assessed at 4, 8 and 16 weeks after surgery by histologic and computer-assisted histometric analysis. The results demonstrated a substantial augmentation of on average 141% (SD 18) of the skull's thickness after 16 weeks in the controls, indicating that a predictable bone formation can be achieved beneath completely occlusive barriers over a non-injured cortical layer. In all test groups, a significantly larger bone augmentation was observed after 16 weeks compared to the control sites 172.8% (SD 41.7) in group I (P < 0.05), 172.0% (SD 18.4) in group II (P < 0.05) and 221.5% (SD 42.3) in group III (P < 0.001), demonstrating that stimulating blood supply and bone forming cells access by cortical perforations and/or blood clot addition enhances de novo bone formation in this experimental model

Influence of low-intensity pulsed ultrasound on bone repair upon irradiation: a histomorphometric study in rabbits.

The present study evaluated the influence of LIPUS on regeneration processes of bone defects below the critical size in irradiated and non-irradiated rabbit tibia. The study was based on a total of six white New-Zealand adult female rabbits. Apart from surgery to create bone defects on all tibiae, the following four treatments were randomly added on: (1) C group: only the surgical procedure was applied with no additional treatment, serving as the control, (2) R group, the irradiated side received 15 Gy in single dose, (3) US group, treated with LIPUS, and (4) R+US group, irradiated with 15 Gy and treated with LIPUS (n=6 defects per group). The surgery control samples showed 83.10% ± 17.79% of bone repair after 9 weeks, while the irradiated bone had significantly (p 0.05) improve the response compared to the non-treated irradiated specimens. In the irradiated bones, ultrasound treatment produced only 3.89% less new bone compared to the untreated control group; this repair is insignificantly lower than the natural bone healing in the untreated control group. LIPUS treatment on non-irradiated bone, however, showed bone formations beyond the size defect (115.91% ± 33.69%), highly significantly different when compared to the control group or any irradiated group. It is noteworthy that the application of ultrasound to healthy bone produced highly significantly enhanced bone formations, with 36.70% more regenerated bone when comparing the same application on irradiated bone (79.21% ± 21.07%). LIPUS vibration stimuli may be considered as a promising complementary treatment approach in non-irradiated bone regeneration procedures to shorten the treatment and to enhance the bone healing. In irradiated bones, the effect of ultrasound application is less apparent and further studies are needed to refine the dynamics of the present results.Peer reviewe

Bioactive glass particles and deproteinized bovine bone mineral as scaffold in bone tissue regeneration:effects of Minocycline-HCL.

peer reviewedAim/Hypothesis: Bone tissue regeneration remains an important challenge in orthopaedic and maxillofacial surgery. The present study in rat was performed to determine if Minocycline could influence the behavior of Deproteinized Bovine Bone Mineral (DBBM) and bioactive glass particles when used as scaffold for Guided Bone Regeneration (GBR). Minocycline is a wide spectrum antibiotic with demonstrated effects on bone formation, bone resorption and connective tissue breakdown. We chose to investigate this molecule in relation with bioactive glasses and DBBM, both important classes of bone grafting materials. Material and methods: Two completely occlusive titanium bone augmentation caps were placed on each side of the sagittal cranial suture of the rat calvaria. One was filled with bioactive glass particles (BioGran-Biomet 3i, Plam Beach, FL, USA) and the second with DBBM particles (Bio-Oss®–Geistlich, Wolhusen, Switzerland). Bone filler particles were mixed with blood, collected from the animal’s tail, and a drop of balanced salt solution in order to acquire a moldable consistency of the particles and a perfectly adapted fill of the regeneration chambers. In Minocycline-Cl group (n=10) bone grafts were additionally placed into a minocycline solution at 0.1 mg/ml prior placement. The study protocol included animal accommodation with water ad libitum, regular rat pellet with artificial light with a night and day cycle. All surgeries were conducted under strict aseptic conditions. For each observation time (4, 8 and 16 weeks) two calvaria were embedded in methyl methacrylate resin and cut in thin serial sections (100-200 µm), grounded and polished to a thickness of 20-40 µm. A Giemsa (Gross & Strunz, 1977), Paragon and a combination of Stevenel’s blue with Van Gieson staining was used for light microscopy. The remaining calvaria were fixed, decalcified in an EDTA solution at 0.2 M (pH 7.4) for 30 days and dehydrated in ascending ethanol series for 96 h. The paraffin embedded blocks were sectioned (5 µm) and either hematoxylin eosin (H&E) or Toluidine blue stained for the histologic analysis. Results: This study has confirmed osteoconductive and osteoinductive response of BioGran. The addition of Minocycline has hardly influenced the result positively. In contact with blood, BioGran underwent a surface modification in form of a calcium phosphate precipitate, quite similar in composition and structure to hydroxyapatite. Cracks in the outer shell were to be recognized and the silica core tended to disappear leaving a calcium phosphate pouch for future bone growth. Likewise, first signs of osteoinduction in the form of ectopic mineralization foci could be observed after just 4 weeks at some distance from BioGran particles. These ossification islets were lined by a layer of osteoblasts for centrifugal expansion. The osteoconductivity and predictability of Bio-Oss®, are well documented. Some studies however found that Bio-Oss® inhibited new bone formation or interfered with new bone generation especially when used as an onlay graft under totally occlusive capsules in a GTR model. Our observations were similar: the major part of the biomaterial particles was embedded in connective tissue. Most of the new bone regenerated were lamellar bone formations in close contact and bonded to the DBBM particles. Islands of spontaneous ossification suggesting some osteoinductive activities could only be observed in Bio-Oss® sections treated with Minocycline. A possible correlation of these centres with the basal skull bone, outside of our observation field, cannot be excluded. Conclusions and clinical implications: The osteoconductive and osteoinductive properties of bioactive glass particles could be confirmed within the limitations of the present study. Minocycline-HCl may be considered as a promising complementary treatment approach and may add some osteoinductive properties to DBBM. Further investigations into the volume of the newly generated bone are needed to refine the present results

Minocycline hydrochloride as a potential adjuvant to improve osteoconductive and osteoinductive properties of bone substitutes in an extra-skeletal bone augmentation model: Preliminary observations in rats

Aim/Hypothesis: Bone tissue regeneration remains an important challenge in orthopedic and maxillofacial surgery. The present in vivo study was performed to determine if minocycline-hydrochloride (minocycline-HCl) could influence the behavior of Deproteinized Bovine Bone Mineral (DBBM) and bioactive glass particles when used as filler material for extra-skeletal bone generation in a Guided Bone Augmentation (GBA) model. Material and methods: An occlusive titanium cap was placed on each side of the sagittal cranial suture of the rat calvaria. One was filled with bioactive glass particles, the second with DBBM particles, both previously mixed with blood (control groups). In minocycline-HCl loaded groups (experimental groups), bone grafts were additionally placed into a minocycline solution. For each observation time (4, 8 and 16 weeks) samples were harvested and processed for histology. Half of the samples were embedded in methylmethacrylate for undecalcified histology whereas the other half was fixed, decalcified and embedded in paraffin for classical histologic analysis. Results: This study highlighted osteoconductive and osteoinductive responses associated to bioactive glass particles. However, the addition of minocycline-HCl had no measurable influence on the result. In the control groups, the major part of the space originally created by the caps was occupied by biomaterial particles surrounded by connective tissue. Only slight new bone formations could be seen in the bottom region close to the native skull bone. In sections of minocycline-HCl loaded DBBM, areas of spontaneous ossification could be observed both, after 8 weeks and 16 weeks. Conclusions and clinical implications: Our observations suggest osteoconductive and osteoinductive properties of bioactive glass particles within the limitations of the present study. Minocycline-HCl may be considered as a promising complementary treatment approach and may add some osteoinductive properties to DBBM. Further investigations as to the volume of newly generated bone are needed to refine the present results

The genomes of two key bumblebee species with primitive eusocial organization

Background: The 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.Results: We 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.Conclusions: These 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

Genomic signatures of evolutionary transitions from solitary to group living

The evolution of eusociality is one of the major transitions in evolution, but the underlying genomic changes are unknown. We compared the genomes of 10 bee species that vary in social complexity, representing multiple independent transitions in social evolution, and report three major findings. First, many important genes show evidence of neutral evolution as a consequence of relaxed selection with increasing social complexity. Second, there is no single road map to eusociality; independent evolutionary transitions in sociality have independent genetic underpinnings. Third, though clearly independent in detail, these transitions do have similar general features, including an increase in constrained protein evolution accompanied by increases in the potential for gene regulation and decreases in diversity and abundance of transposable elements. Eusociality may arise through different mechanisms each time, but would likely always involve an increase in the complexity of gene networks