A hamster model for stress-induced weight gain.

This review addresses the translational relevance of animal models of stress and their effects on body weight. In humans, stress, whether chronic or acute, has often been associated with increased food intake and weight gain. In view of the current obesity epidemic, this phenomenon is especially relevant. Such observations contrast with reports with commonly used laboratory animals, especially rats and mice. In these species, it is common to find individuals gaining less weight under stress, even with potent social stressors. However, there are laboratory species that present increased appetite and weight gain under stress, such as golden hamsters. Furthermore, these animals also include metabolic and behavioral similarities with humans, including hoarding behavior which is also enhanced under stress. Consequently, we propose that our comparative perspective provides useful insights for future research on the development of obesity in humans as a consequence of chronic stress exposure.

The phylogeny and evolutionary ecology of hoverflies (Diptera: Syrphidae) inferred from mitochondrial genomes.

Hoverflies (Diptera: Syrphidae) are a diverse group of pollinators and a major research focus in ecology, but their phylogenetic relationships remain incompletely known. Using a genome skimming approach we generated mitochondrial genomes for 91 species, capturing a wide taxonomic diversity of the family. To reduce the required amount of input DNA and overall cost of the library construction, sequencing and assembly was conducted on mixtures of specimens, which raises the problem of chimera formation of mitogenomes. We present a novel chimera detection test based on gene tree incongruence, but identified only a single mitogenome of chimeric origin. Together with existing data for a final set of 127 taxa, phylogenetic analysis on nucleotide and amino acid sequences using Maximum Likelihood and Bayesian Inference revealed a basal split of Microdontinae from all other syrphids. The remainder consists of several deep clades assigned to the subfamily Eristalinae in the current classification, including a clade comprising the subfamily Syrphinae (plus Pipizinae). These findings call for a re-definition of subfamilies, but basal nodes had insufficient support to fully justify such action. Molecular-clock dating placed the origin of the Syrphidae crown group in the mid-Cretaceous while the Eristalinae-Syrphinae clade likely originated near the K/Pg boundary. Transformation of larval life history characters on the tree suggests that Syrphidae initially had sap feeding larvae, which diversified greatly in diet and habitat association during the Eocene and Oligocene, coinciding with the diversification of angiosperms and the evolution of various insect groups used as larval host, prey, or mimicry models. Mitogenomes proved to be a powerful phylogenetic marker for studies of Syrphidae at subfamily and tribe levels, allowing dense taxon sampling that provided insight into the great ecological diversity and rapid evolution of larval life history traits of the hoverflies.

Lifelong enhancement of body mass from adolescent stress in male hamsters.

In hamsters, exposure to stress in adulthood causes increased body weight. We addressed how social stress during puberty would impact food intake and body weight. Stressed hamsters started gaining significantly more weight than controls after only two days of stress exposure. Over a two-week period, stressed subjects gained 10% more weight and consumed more food than controls. At the end of the stress period, stressed hamsters collected nearly twice as many palatable sugar pellets from an arena than controls. Stressed subjects presented 15-20% more body fat in mesenteric, inguinal, and retroperitoneal fat pads. In order to assess the duration of these effects, we analyzed data from previous studies keeping hamsters for over two months past the stress period in puberty. Our analysis shows that stressed hamsters stopped gaining more weight after the stress period, but their body weights remained elevated for over two months, consistently weighing 10% more than their non-stressed counterparts. We also analyzed conditioning training data collected after the period of stress in late puberty and early adulthood (P56 to P70) that was part of the original studies. Training consisted of lever pressing for palatable food rewards. At these times, previously stressed hamsters retrieved similar numbers of food pellets from the conditioning chambers, suggesting no difference in appetite after the stress period. These data showing a long-lasting effect of stress on body weight may be relevant to studies on the ontogeny of lifelong obesity.

Taxonomic revision of Romaleosyrphus Bigot (Diptera, Syrphidae), including descriptions of seven new species.

The genus Romaleosyrphus Bigot is reviewed, including the description of seven new species (R.argosi Moran, sp. nov., R.bigoti Moran, sp. nov., R.drysus Moran, sp. nov., R.nephelaeus Moran & Thompson, sp. nov., R.soletluna Moran & Thompson, sp. nov., R.vockerothi Moran & Thompson, sp. nov. and R.woodi Moran, sp. nov.). Romaleosyrphusarctophiloides (Giglio-Tos), comb. nov. is transferred to Romaleosyrphus. Romaleosyrphus stat. rev. is redefined to represent the monophyletic unit of species within Criorhinina which possess holoptic males, a proximal ventral half of vein C with setae, a broad intersection of vein R1 with vein C, the distal part of R4+5 beyond M1 longer than cross-vein h and appressed pile on the abdomen. Descriptions, habitus and genitalia photographs, distributions, and an illustrated key for all nine Romaleosyrphus are presented. DNA barcode data are provided for eight of the species with a cytochrome c oxidase subunit I gene tree presented and discussed.

New Syrphidae (Diptera) of North-eastern North America.

BACKGROUND: This paper describes 11 of 18 new species recognised in the recent book, "Field Guide to the Flower Flies of Northeastern North America". Four species are omitted as they need to be described in the context of a revision (three Cheilosia and a Palpada species) and three other species (one Neoascia and two Xylota) will be described by F. Christian Thompson in a planned publication. Six of the new species have been recognised for decades and were treated by J. Richard Vockeroth in unpublished notes or by Thompson in his unpublished but widely distributed "A conspectus of the flower flies (Diptera: Syrphidae) of the Nearctic Region". Five of the 11 species were discovered during the preparation of the Field Guide. Eight of the 11 have DNA barcodes available that support the morphology. NEW INFORMATION: New species treated in this paper include: Anasimyia diffusa Locke, Skevington and Vockeroth (Smooth-legged Swamp Fly), Anasimyia matutina Locke, Skevington and Vockeroth (Small-spotted Swamp Fly), Brachyopa caesariata Moran and Skevington (Plain-winged Sapeater), Brachyopa cummingi Moran and Skevington (Somber Sapeater), Hammerschmidtia sedmani Vockeroth, Moran and Skevington (Pale-bristled Logsitter), Microdon (Microdon) scauros Skevington and Locke (Big-footed Ant Fly), Mixogaster fattigi Locke, Skevington and Greene (Fattig's Ant Fly), Neoascia guttata Skevington and Moran (Spotted Fen Fly), Orthonevra feei Moran and Skevington (Fee's Mucksucker), Psilota klymkoi Locke, Young and Skevington (Black Haireye) and Trichopsomyia litoralis Vockeroth and Young (Coastal Psyllid-killer). Common names follow the "Field Guide to the Flower Flies of Northeastern North America" (Skevington et al. 2019).

An injectable method for noninvasive spine fusion.

BACKGROUND CONTEXT: Bone morphogenetic proteins (BMPs) induce bone formation but are difficult to localize, and subsequent diffusion from the site of interest and short half-life reduce the efficacy of the protein. Currently, spine fusion requires stripping, decortications of the transverse processes, and an autograft harvest procedure. Even in combination with BMPs, clinical spinal fusion has a high failure rate, presumably because of difficulties in localizing sufficient levels of BMP. PURPOSE: The goal was to achieve reliable spine fusion through a single injection of a cell-based gene therapy system without the need for any surgical intervention. STUDY DESIGN: Eighty-seven immunodeficient (n=44) and immune-competent (n=43) mice were injected along the paraspinous musculature to achieve rapid induction of heterotopic ossification (HO) and ultimately spinal arthrodesis. METHODS: Immunodeficient and immune-competent mice were injected with fibroblasts, transduced with an adenoviral vector to express BMP2, along the paraspinous musculature. Bone formation was evaluated via radiographs, microcomputed tomography, and biomechanical analysis. RESULTS: ew bridging bone between the vertebrae and the fusion to adjacent skeletal bone was obtained as early as 2 weeks. Reduction in spine flexion-extension also occurred as early as 2 weeks after injection of the gene therapy system, with greater than 90% fusion by 4 weeks in all animals regardless of their genetic background. CONCLUSIONS: Injection of our cell-based system into the paraspinous musculature induces spinal fusion that is dependent neither on the cell type nor on the immune status. These studies are the first to harness HO in an immune-competent model as a noninvasive injectable system for clinically relevant spinal fusion and may one day impact human spinal arthrodesis.

Hypoxic adipocytes pattern early heterotopic bone formation.

The factors contributing to heterotopic ossification, the formation of bone in abnormal soft-tissue locations, are beginning to emerge, but little is known about microenvironmental conditions promoting this often devastating disease. Using a murine model in which endochondral bone formation is triggered in muscle by bone morphogenetic protein 2 (BMP2), we studied changes near the site of injection of BMP2-expressing cells. As early as 24 hours later, brown adipocytes began accumulating in the lesional area. These cells stained positively for pimonidazole and therefore generated hypoxic stress within the target tissue, a prerequisite for the differentiation of stem cells to chondrocytes and subsequent heterotopic bone formation. We propose that aberrant expression of BMPs in soft tissue stimulates production of brown adipocytes, which drive the early steps of heterotopic endochondral ossification by lowering oxygen tension in adjacent tissue, creating the correct environment for chondrogenesis. Results in misty gray lean mutant mice not producing brown fat suggest that white adipocytes convert into fat-oxidizing cells when brown adipocytes are unavailable, providing a compensatory mechanism for generation of a hypoxic microenvironment. Manipulation of the transcriptional control of adipocyte fate in local soft-tissue environments may offer a means to prevent or treat development of bone in extraskeletal sites.