Search for Gamma-Ray Spectral Lines from Dark Matter Annihilation up to 100 TeV toward the Galactic Center with MAGIC

Linelike features in TeV γ rays constitute a "smoking gun" for TeV-scale particle dark matter and new physics. Probing the Galactic Center region with ground-based Cherenkov telescopes enables the search for TeV spectral features in immediate association with a dense dark matter reservoir at a sensitivity out of reach for satellite γ-ray detectors, and direct detection and collider experiments. We report on 223 hours of observations of the Galactic Center region with the MAGIC stereoscopic telescope system reaching γ-ray energies up to 100 TeV. We improved the sensitivity to spectral lines at high energies using large-zenith-angle observations and a novel background modeling method within a maximum-likelihood analysis in the energy domain. No linelike spectral feature is found in our analysis. Therefore, we constrain the cross section for dark matter annihilation into two photons to ⟨σv⟩≲5×10^{-28}  cm^{3} s^{-1} at 1 TeV and ⟨σv⟩≲1×10^{-25}  cm^{3} s^{-1} at 100 TeV, achieving the best limits to date for a dark matter mass above 20 TeV and a cuspy dark matter profile at the Galactic Center. Finally, we use the derived limits for both cuspy and cored dark matter profiles to constrain supersymmetric wino models.

Ketogenic diet uncovers differential metabolic plasticity of brain cells

To maintain homeostasis, the body, including the brain, reprograms its metabolism in response to altered nutrition or disease. However, the consequences of these challenges for the energy metabolism of the different brain cell types remain unknown. Here, we generated a proteome atlas of the major central nervous system (CNS) cell types from young and adult mice, after feeding the therapeutically relevant low-carbohydrate, high-fat ketogenic diet (KD) and during neuroinflammation. Under steady-state conditions, CNS cell types prefer distinct modes of energy metabolism. Unexpectedly, the comparison with KD revealed distinct cell type-specific strategies to manage the altered availability of energy metabolites. Astrocytes and neurons but not oligodendrocytes demonstrated metabolic plasticity. Moreover, inflammatory demyelinating disease changed the neuronal metabolic signature in a similar direction as KD. Together, these findings highlight the importance of the metabolic cross-talk between CNS cells and between the periphery and the brain to manage altered nutrition and neurological disease.

Hyperactivity is a Core Endophenotype of Elevated Neuregulin-1 Signaling in Embryonic Glutamatergic Networks

The neuregulin 1 (NRG1) ErbB4 module is at the core of an "at risk" signaling pathway in schizophrenia. Several human studies suggest hyperstimulation of NRG1-ErbB4 signaling as a plausible pathomechanism; however, little is known about the significance of stage-, brain area-, or neural cell type-specific NRG1-ErbB4 hyperactivity for disease-relevant brain endophenotypes. To address these spatiotemporal aspects, we generated transgenic mice for Cre recombinase-mediated overexpression of cystein-rich domain (CRD) NRG1, the most prominent NRG1 isoform in the brain. A comparison of "brain-wide" vs cell type-specific CRD-NRG1 overexpressing mice revealed that pathogenic CRD-NRG1 signals for ventricular enlargement and neuroinflammation originate outside glutamatergic neurons and suggests a subcortical function of CRD-NRG1 in the control of body weight. Embryonic onset of CRD-NRG1 in glutamatergic cortical networks resulted in reduced inhibitory neurotransmission and locomotor hyperactivity. Our findings identify ventricular enlargement and locomotor hyperactivity, 2 main endophenotypes of schizophrenia, as specific consequences of spatiotemporally distinct expression profiles of hyperactivated CRD-NRG1 signaling.

Synergistic PXT3003 therapy uncouples neuromuscular function from dysmyelination in male Charcot-Marie-Tooth disease type 1A (CMT1A) rats

Charcot-Marie-Tooth disease 1 A (CMT1A) is caused by an intrachromosomal duplication of the gene encoding for PMP22 leading to peripheral nerve dysmyelination, axonal loss, and progressive muscle weakness. No therapy is available. PXT3003 is a low-dose combination of baclofen, naltrexone, and sorbitol which has been shown to improve disease symptoms in Pmp22 transgenic rats, a bona fide model of CMT1A disease. However, the superiority of PXT3003 over its single components or dual combinations have not been tested. Here, we show that in a dorsal root ganglion (DRG) co-culture system derived from transgenic rats, PXT3003 induced myelination when compared to its single and dual components. Applying a clinically relevant ("translational") study design in adult male CMT1A rats for 3 months, PXT3003, but not its dual components, resulted in improved performance in behavioral motor and sensory endpoints when compared to placebo. Unexpectedly, we observed only a marginally increased number of myelinated axons in nerves from PXT3003-treated CMT1A rats. However, in electrophysiology, motor latencies correlated with increased grip strength indicating a possible effect of PXT3003 on neuromuscular junctions (NMJs) and muscle fiber pathology. Indeed, PXT3003-treated CMT1A rats displayed an increased perimeter of individual NMJs and a larger number of functional NMJs. Moreover, muscles of PXT3003 CMT1A rats displayed less neurogenic atrophy and a shift toward fast contracting muscle fibers. We suggest that ameliorated motor function in PXT3003-treated CMT1A rats result from restored NMJ function and muscle innervation, independent from myelination.

120 THE DEVELOPMENTAL COMPETENCE OF TADPOLES PRODUCED IN VITRO FROM THE ENDANGERED DUSKY GOPHER FROG (RANA SEVOSA) USING EXOGENOUS HORMONE TREATMENT

Dusky gopher frogs once existed throughout the states of Mississippi, Alabama and Louisiana. Presently, the USA Fish and Wildlife Service estimates that there are less than 100 frogs left in the wild, with almost all of these residing in a single pond in Mississippi, making the dusky gopher frog America's most endangered frog species. Their habitat has been threatened by residential and forestry development, as well as from fire suppression and the decline of gopher tortoises, whose burrows the frogs use for shelter. The USA Fish and Wildlife Service brought the first dusky gopher frogs into captivity in 2001 and they have been kept at the Memphis Zoo since 2003 and at Omaha's Henry Doorly Zoo since 2004. Natural breeding attempts in captivity have been unsuccessful despite efforts to artificially mimic what is known to be the appropriate seasonal environmental (e.g. light, humidity, temperature) and social cues (e.g. calls from wild frogs during the breeding season) that stimulate reproduction in situ. Also, there was a concern about the incidences of abnormalities (e.g. spindly legs) from inadequate husbandry conditions (e.g. nutritional deficiencies) or diseases in tadpoles and froglets produced ex situ (e.g. dermomycoides). The objectives of this study were (1) to examine the developmental competence of tadpoles produced by exogenous hormone treatment for IVF to complete normal metamorphosis into viable froglets ex situ and (2) to determine the incidence of developmental abnormalities or dermomycoides in the froglets produced ex situ. Males and females were first separated by the identification of black male nuptial pads used during amplexus. Males and females were stimulated to spermiate and ovulate, respectively, using a variation of a standard amphibian hormonal stimulation protocol (Kouba et al. 2012 Reprod. Fertil. Dev. 24). As a result, more than 1460 viable tadpoles (61% of fertilized eggs) were produced from 18 segregated genetic pairings. To date, 602 (41%) of the tadpoles have completed normal metamorphosis into viable froglets (over 6 times the known existing population in situ), 51% were either culled to examine for dermomycoides or died for a variety of known (accidental) and unknown reasons (abnormal appendage development accounting for less than 7%) and 8% have yet to metamorphose after 9 months. The incidence of dermomycoides in the culled individuals was 100%; however, a study being conducted concurrently in their native habitat has confirmed that the organism does exist in situ with the dusky gopher frogs, which act as natural carriers. Efforts are currently in place to establish reintroduction programs for the dusky gopher froglets produced ex situ to increase the dwindling wild population now that tadpoles produced by IVF have been shown to be developmentally competent. In conclusion, IVF can be used to produce tadpoles of the dusky gopher frog with a low incidence of abnormalities, but the tadpoles were found to be carriers of the organism dermomycoides similar to their counterparts in the wild.

116 DEVELOPMENT OF ASSISTED REPRODUCTION TECHNOLOGIES FOR THE ENDANGERED MISSISSIPPI GOPHER FROG (RANA SEVOSA) AND SPERM TRANSFER FOR IN VITRO FERTILIZATION

Species-specific differences in breeding strategies and physiology have limited the application of assisted reproductive technologies (ART) for critically endangered amphibians in captive assurance colonies. In 2006, the Memphis Zoo (MZ) initiated a program to develop ART for the critically endangered Mississippi gopher frog after natural breeding failed. Standard gamete collection and IVF developed by MZ for reproducing endangered toads such as the Wyoming or boreal toad were applied to the gopher frog with little success, especially hormonal therapy for sperm production. Using the leopard frog as a model species for Ranids, we tested the time and dose dependence of a luteinizing hormone releasing hormone analogue (LHRHa) and hCG on sperm quantity and quality. Initial findings from the leopard frog study were critical in designing the study on gopher frogs. Our objectives were to (1) compare 2 different hormones administered intraperitoneal (500 IU hCG vs 15 μg LHRHa) or their combination on spermiation in gopher frogs; (2) develop in vivo oocyte maturation and ovulation protocols using LHRHa (15 μg) and hCG (500 IU); and (3) transfer this technology to another institution as proof of principle. In gopher frogs, 100 and 83% of the males produced sperm in response to the LHRHa and the combination treatment, respectively, whereas only 16% responded to hCG alone. Sperm concentration peaked at 1 h post-administration for all treatments, with the LHRH/hCG cocktail treatment producing the highest concentration of sperm (mean = 4.6 × 106 ± 1.2 × 106 sperm mL–1, n = 6). No differences in motility were observed between treatments (P > 0.05). For females, a series of priming hormones of hCG and LHRHa were given several months before an ovulatory hormone regimen resulting in ovulation by 100% of the females (n = 6), whereas animals not primed failed to ovulate (n = 4). These 3 separate priming and IVF trials conducted between 2008 and 2010 resulted in each female laying ∼2000 eggs, with an average fertilization rate of 76% for inseminated eggs and hundreds of tadpoles produced. These IVF tadpoles represent the first captive reproduction of gopher frogs and highlight how ART can be applied to conservation and genetic management of threatened species. Subsequently, we tested our IVF protocols on gopher frogs at Omaha's Henry Doorly Zoo using fresh (collected on site) and chilled, shipped sperm from MZ. We collected 6169 eggs from 9 hormone-primed females with all animals ovulating. A portion of the total eggs ovulated were inseminated, resulting in 2401 fertilized eggs (38.9% of total eggs collected) across 18 different male–female pairings leading to viable tadpoles. In addition, sperm transferred overnight from the MZ produced 202/441 fertilized eggs (46%). The transfer of this technology and production of endangered amphibians using chilled, shipped sperm from live animals is a conservation milestone that can be applied to other captive breeding programs.