MC3R links nutritional state to childhood growth and the timing of puberty.

The state of somatic energy stores in metazoans is communicated to the brain, which regulates key aspects of behaviour, growth, nutrient partitioning and development1. The central melanocortin system acts through melanocortin 4 receptor (MC4R) to control appetite, food intake and energy expenditure2. Here we present evidence that MC3R regulates the timing of sexual maturation, the rate of linear growth and the accrual of lean mass, which are all energy-sensitive processes. We found that humans who carry loss-of-function mutations in MC3R, including a rare homozygote individual, have a later onset of puberty. Consistent with previous findings in mice, they also had reduced linear growth, lean mass and circulating levels of IGF1. Mice lacking Mc3r had delayed sexual maturation and an insensitivity of reproductive cycle length to nutritional perturbation. The expression of Mc3r is enriched in hypothalamic neurons that control reproduction and growth, and expression increases during postnatal development in a manner that is consistent with a role in the regulation of sexual maturation. These findings suggest a bifurcating model of nutrient sensing by the central melanocortin pathway with signalling through MC4R controlling the acquisition and retention of calories, whereas signalling through MC3R primarily regulates the disposition of calories into growth, lean mass and the timing of sexual maturation.

Correction: Investigation of common, low-frequency and rare genome-wide variation in anorexia nervosa.

The fortieth author's name was listed incorrectly. The correct presentation is A Keski-Rahkonen.

Investigation of common, low-frequency and rare genome-wide variation in anorexia nervosa.

Anorexia nervosa (AN) is a complex neuropsychiatric disorder presenting with dangerously low body weight, and a deep and persistent fear of gaining weight. To date, only one genome-wide significant locus associated with AN has been identified. We performed an exome-chip based genome-wide association studies (GWAS) in 2158 cases from nine populations of European origin and 15 485 ancestrally matched controls. Unlike previous studies, this GWAS also probed association in low-frequency and rare variants. Sixteen independent variants were taken forward for in silico and de novo replication (11 common and 5 rare). No findings reached genome-wide significance. Two notable common variants were identified: rs10791286, an intronic variant in OPCML (P=9.89 × 10-6), and rs7700147, an intergenic variant (P=2.93 × 10-5). No low-frequency variant associations were identified at genome-wide significance, although the study was well-powered to detect low-frequency variants with large effect sizes, suggesting that there may be no AN loci in this genomic search space with large effect sizes.

Properties of a Rare-Earth-Ion-Doped Waveguide at Sub-Kelvin Temperatures for Quantum Signal Processing.

We characterize the 795 nm ^{3}H_{6} to ^{3}H_{4} transition of Tm^{3+} in a Ti^{4+}:LiNbO_{3} waveguide at temperatures as low as 800 mK. Coherence and hyperfine population lifetimes-up to 117 µs and 2.5 h, respectively-exceed those at 3 K at least tenfold, and are equivalent to those observed in a bulk Tm^{3+}:LiNbO_{3} crystal under similar conditions. We also find a transition dipole moment that is equivalent to that of the bulk. Finally, we prepare a 0.5 GHz-bandwidth atomic frequency comb of finesse >2 on a vanishing background. These results demonstrate the suitability of rare-earth-ion-doped waveguides created using industry-standard Ti indiffusion in LiNbO_{3} for on-chip quantum applications.

A genome-wide association study of anorexia nervosa.

Anorexia nervosa (AN) is a complex and heritable eating disorder characterized by dangerously low body weight. Neither candidate gene studies nor an initial genome-wide association study (GWAS) have yielded significant and replicated results. We performed a GWAS in 2907 cases with AN from 14 countries (15 sites) and 14 860 ancestrally matched controls as part of the Genetic Consortium for AN (GCAN) and the Wellcome Trust Case Control Consortium 3 (WTCCC3). Individual association analyses were conducted in each stratum and meta-analyzed across all 15 discovery data sets. Seventy-six (72 independent) single nucleotide polymorphisms were taken forward for in silico (two data sets) or de novo (13 data sets) replication genotyping in 2677 independent AN cases and 8629 European ancestry controls along with 458 AN cases and 421 controls from Japan. The final global meta-analysis across discovery and replication data sets comprised 5551 AN cases and 21 080 controls. AN subtype analyses (1606 AN restricting; 1445 AN binge-purge) were performed. No findings reached genome-wide significance. Two intronic variants were suggestively associated: rs9839776 (P=3.01 × 10(-7)) in SOX2OT and rs17030795 (P=5.84 × 10(-6)) in PPP3CA. Two additional signals were specific to Europeans: rs1523921 (P=5.76 × 10(-)(6)) between CUL3 and FAM124B and rs1886797 (P=8.05 × 10(-)(6)) near SPATA13. Comparing discovery with replication results, 76% of the effects were in the same direction, an observation highly unlikely to be due to chance (P=4 × 10(-6)), strongly suggesting that true findings exist but our sample, the largest yet reported, was underpowered for their detection. The accrual of large genotyped AN case-control samples should be an immediate priority for the field.

Tm 3+ Tm 3+ : Y3Ga5O12 materials for spectrally multiplexed quantum memories.

We investigate the relevant spectroscopic properties of the 795 nm (3)H(6)↔(3)H(4) transition in 1% Tm(3+):Y(3)Ga(5)O(12) at temperatures as low as 1.2 K for optical quantum memories based on persistent spectral tailoring of narrow absorption features. Our measurements reveal that this transition has uniform coherence properties over a 56 GHz bandwidth, and a simple hyperfine structure split by ± 44 MHz/T with lifetimes of up to hours. Furthermore, we find a (3)F(4) population lifetime of 64 ms-one of the longest lifetimes observed for an electronic level in a solid--and an exceptionally long coherence lifetime of 490 µs--the longest ever observed for optical transitions of Tm(3+) ions in a crystal. Our results suggest that this material allows realizing broadband quantum memories that enable spectrally multiplexed quantum repeaters.

Energy expenditure in obese children with pseudohypoparathyroidism type 1a.

CONTEXT: Patients with pseudohypoparathyroidism type 1a (PHP-1a) develop early-onset obesity. The abnormality in energy expenditure and/or energy intake responsible for this weight gain is unknown. OBJECTIVE: The aim of this study was to evaluate energy expenditure in children with PHP-1a compared with obese controls. PATIENTS: We studied 6 obese females with PHP-1a and 17 obese female controls. Patients were recruited from a single academic center. MEASUREMENTS: Resting energy expenditure (REE) and thermogenic effect of a high fat meal were measured using whole room indirect calorimetry. Body composition was assessed using whole body dual energy x-ray absorptiometry. Fasting glucose, insulin, and hemoglobin A1C were measured. RESULTS: Children with PHP-1a had decreased REE compared with obese controls (P<0.01). After adjustment for fat-free mass, the PHP-1a group's REE was 346.4 kcals day(-1) less than obese controls (95% CI (-585.5--106.9), P<0.01). The thermogenic effect of food (TEF), expressed as percent increase in postprandial energy expenditure over REE, was lower in PHP-1a patients than obese controls, but did not reach statistical significance (absolute reduction of 5.9%, 95% CI (-12.2-0.3%), P=0.06). CONCLUSIONS: Our data indicate that children with PHP-1a have decreased REE compared with the obese controls, and that may contribute to the development of obesity in these children. These patients may also have abnormal diet-induced thermogenesis in response to a high-fat meal. Understanding the causes of obesity in PHP-1a may allow for targeted nutritional or pharmacologic treatments in the future.

A non-epistatic interaction of agouti and extension in the fox, Vulpes vulpes.

Agouti and extension are two genes that control the production of yellow-red (phaeomelanin) and brown-black (eumelanin) pigments in the mammalian coat. Extension encodes the melanocyte-stimulating hormone receptor (MC1R) while agouti encodes a peptide antagonist of the receptor. In the mouse, extension is epistatic to agouti, hence dominant mutants of the MC1R encoding constitutively active receptors are not inhibited by the agouti antagonist, and animals with dominant alleles of both loci remain darkly pigmented. In the fox the proposed extension locus is not epistatic to the agouti locus. We have cloned and characterized the MC1R and the agouti gene in coat colour variants of the fox (Vulpes vulpes). A constitutively activating C125R mutation in the MC1R was found specifically in darkly pigmented animals carrying the Alaska Silver allele (EA). A deletion in the first coding exon of the agouti gene was found associated with the proposed recessive allele of agouti in the darkly pigmented Standard Silver fox (aa). Thus, as in the mouse, dark pigmentation can be caused by a constitutively active MC1R, or homozygous recessive status at the agouti locus. Our results, demonstrating the presence of dominant extension alleles in foxes with significant red coat colouration, suggest the ability of the fox agouti protein to counteract the signalling activity of a constitutively active fox MC1R.

Regulation of the immune system by synthetic polynucleotides. 3. Action on antigen-reactive cells of thymic origin.

Polyadenylic-polyuridylic acid complexes, a potent adjuvant to the immune response, were tested for action on thymic-influenced and bone marrow-derived lymphocytes in model systems deficient in one or the other of these cells. Adult mice, thymectomized at birth or mice treated with heterologous antithymocyte serum produced 90-95% fewer splenic rosette-forming cells than normal mice in response to an injection of sheep erythrocytes. Intravenous injection of complexes of homoribopolynucleotides, polyadenylic and polyuridylic acids, poly A:U with SRBC restored immunologic competence to NTx- or ATS-treated mice such that they produced normal or near normal levels of splenic RFC. In addition, injection of poly A:U enabled NTx mice to reject allogeneic skin grafts at the same rate as control mice with an intact thymus. Further reduction in residual thymocytes by combining neonatal thymectomy with ATS treatment reduced the number of anti-SRBC RFC induced by poly A:U. Lethally irradiated mice which received SRBC, excess bone marrow cells, and as few as 40,000 thymic lymphocytes were stimulated by poly A:U to produce RFC. No adjuvant effect was observed when irradiated mice received excess thymic lymphocytes and low doses of bone marrow cells with poly A:U. The results suggested that the adjuvant action of poly A:U was exerted on the thymic-influenced, antigen-reactive cell and that restoration of immunocompetence to NTx- or ATS-treated mice was caused by amplification of a small number of residual antigen-reactive cells which were influenced by the thymus in utero before thymectomy, or which survived treatment with ATS.

Selective turnover and shedding of H-2K and H-2D antigens is controlled by the major histocompatibility complex. Implications for H-2-restricted recognition.

Lactoperoxidase-catalyzed cell surface radioiodination and incorporation of [3H]-leucine were employed to radiolabel H-2K and H-2D antigens of murine spleen cells. The fate of H-2 antigens was monitored by in vitro culture of labeled cells and isolation of labeled antigens from detergent lysates of the cells and culture supernates obtained at different times during culture. H-2Kk antigens were found to be rapidly turned over and shed by CBA/J cells, whereas the turnover of H-2Dk antigens was extremely slow. Analysis of the membrane residence times of surface-labeled H-2K and H-2D antigens on spleen cells from various H-2-congenic and -recombinant strains demonstrated variations in the shedding rates of H-2K and H-2D antigens, which were controlled by genes mapping in the major histocompatibility complex. These variations show a striking correlation with published, genetically controlled quantitative variations in the cytotoxic response of T lymphocytes to chemically modified or virus-infected syngeneic cells.

Lymphocyte membrane dynamics. Metabolic release of cell surface proteins.

Cell surface proteins of normal and neoplastic lymphocytes were labeled with iodide-(125)I by lactoperoxidase-catalyzed iodination. Incubation of (125)I-labeled iodide cells in vitro resulted in the release of iodinated surface proteins at a rapid rate which was dependent on cellular respiration and protein synthesis. Comparisons by disc electrophoresis showed a marked similarity between urea-soluble surface proteins extracted from iodinated cells and iodinated material released by the cells during in vitro incubation. The rate of release of cell surface proteins from thymus cells was three times faster than that of spleen cells or bone marrow-derived thoracic duct lymphocytes. In addition, different proteins were released at different rates as evidenced by the rate of release of (125)I of rabbit anti-mouse immunoglobulin specifically bound to mouse spleen cells and comparisons by disc electrophoresis of urea-soluble iodinated surface proteins extracted from cells before and after incubation. The results suggest that a dynamic state exists at the cell surface. The possible role of the release of cell surface proteins in cell regulation and communication is discussed.

Isolation and partial characterization of lymphocyte surface immunoglobulins.

Immunoglobulins were isolated from the surfaces of lymphocytes from a variety of lymphocyte populations including murine and human thymus lymphocytes and murine spleen and thoracic duct lymphocytes. Cell surface proteins were labeled with iodide-(125)I by lactoperoxidase-catalyzed iodination, and recovered in solution either by solubilization in dissociating solvents or active metabolic release. Immunoglobulins were identified and isolated by immunological coprecipitation. The polypeptide chain structure of immunoglobulins isolated from lymphocyte surfaces was analyzed by polyacrylamide gel electrophoresis of reduced, alkylated samples in acid urea. Human and murine thymus lymphocytes possessed only IgM immunoglobulin on their surfaces. This protein contained light chains and micro-type heavy chains and was characterized by a molecular weight of approximately 200,000. Murine splenic lymphocytes from CBA x C57 animals and congenitally athymic (nu/nu) mice possessed both IgM and IgG on their surfaces. The ratio of micro-chain to gamma-chain was about 3/1. The presence of IgM on thymus lymphocytes probably does not reflect trace contamination by B lymphocytes because comparable quantities of IgM were isolated from both cell populations. Metabolic turnover data suggest that this immunoglobulin is synthesized by the cell population studied. These results provide direct evidence for the presence of immunoglobulins composed of light and heavy polypeptide chains on the surfaces of lymphocytes of all classes.

Nylon adherent antigen-specific rosette-forming T cells.

Shortly after intravenous immunization of mice with heterologous erythrocytes (RBC) antigen-specific Thy 1+ cells which form rosettes with the immunizing RBC (thymic-derived lymphocytes-forming rosettes [T-RFC]) appear in the spleen. These T-RFC are much less stable than Thy 1- RFC (non-thymic-derived [B-RFC]) although most if not all of both classes of RFC adhere to nylon. T-RFC are induced with low doses of antigen (which fail to induce B-RFC) and are inhibited by higher antigen doses which are optimal for induction of B-RFC. Pretreatment of mice with cyclophosphamide prevents the high dose inhibition of T-RFC. Although there are many parallels between the production of T-RFC and delayed-type hypersensitivity (DTH) it is unlikely that the T-RFC are essential for DTH reactions since DTH can be transferred with cells which pass through nylon, and such cells are almost totally depleted of T-RFC. Thus immunization can lead to the production of large numbers of antigen-specific T-RFC whose functional role in the immune response is unknown. However, the characteristics of the T-RFC suggest that they may play an important role in amplification of suppressor cell activity.

Economical Laue x-ray diffraction using photographic film and orientation of single crystals.

Many Laue x-ray diffraction systems using the Polaroid XR-7 Land Diffraction Cassette camera became inactive after production of the required high sensitivity Polaroid T-57 instant film ceased. This Tutorial reports on a low-cost solution using the readily available replacement film with push processing to increase the effective film speed. The use of this film in the polaroid camera is described along with film development and digitization. The orientation of single crystals with the obtained data and free software is explained. A simple method to prepare single crystals with surfaces perpendicular to a desired crystallographic orientation is described. The content of this Tutorial may prove beneficial for educational and research laboratories.

Bacteriorhodopsin induces a light-scattering change in Halobacterium halobium.

When suspensions of Halobacterium halobium are exposed to bright light, the light-scattering properties of the bacteria change. This light-scattering response can produce a transmission decrease of about 1% throughout the red and near-infrared region. The action spectrum for the light-scattering response appropriately matches the absorption spectrum of bacteriorhodopsin. The response is eliminated by cyanide p-trifluoro-methoxyphenylhydrazone, a proton ionophore, and by triphenylmethylphosphonium, a membrane permanent cation. A mild hypertonic shock induces a similar light-scattering change, suggesting that bright light causes the bacteria to shrink about 1% in volume, thereby producing the light-scattering response.

Membrane characteristics and osmotic behavior of isolated rod outer segments.

Freshly isolated frog rod outer segments are sensitive osmometers which retain their photosensitivity; their osmotic behavior reveals essentially the same light-sensitive Na(+) influx observed electrophysiologically in the intact receptor cell. Using appropriate osmotic conditions we have examined freeze-etch replicas of freshly isolated outer segments to identify the membrane which regulates the flow of water and ions. Under isosmotic conditions we find that the disc to disc repeat distance is almost exactly twice the thickness of a disc. This ratio appears to be the same in a variety of vertebrate rod outer segments and can be reliably measured in freeze-etch images. Under all our osmotic conditions the discs appear nearly collapsed. However, when the length of the outer segment is reduced by hyperosmotic shocks the discs move closer together. This markedly reduces the ratio of repeat distance to disc thickness since disc thickness remains essentially constant. Thus, the length reduction of isolated outer segments after hyperosmotic shocks primarily results from reduction of the extradisc volume. Since the discs are free floating and since they undergo negligibly small changes in volume, the plasma membrane alone must be primarily responsible for regulating the water flux and the light-sensitive Na(+) influx in freshly isolated outer segments. On this basis we calculate, from the osmotic behavior, that the plasma membrane of frog rod outer segment has a Na(+) permeability constant of about 2.8 x 10(-6) cm/s and an osmotic permeability coefficient of greater than 2 x 10(-3) cm/s.

The alpha v beta 6 integrin promotes proliferation of colon carcinoma cells through a unique region of the beta 6 cytoplasmic domain.

Cell-matrix interactions are assumed to be important in regulating differentiation and tumor cell growth; however, the precise roles of individual matrix receptors in producing cellular responses are still unclear. We have previously described the alpha v beta 6 integrin, an epithelial cell fibronectin receptor expressed in many carcinoma cell lines. Here we show that heterologous expression of alpha v beta 6 in a human colon carcinoma cell line (SW480) enhances the proliferative capacity of these cells, both in vitro and in vivo in nude mice. This property of alpha v beta 6 correlates with the presence of an 11-amino acid region at the COOH terminus of the beta 6 cytoplasmic domain. This 11-amino acid sequence is required for the growth stimulatory effect, but not for other functions of the beta 6 cytoplasmic domain, such as promoting cell adhesion and focal contact localization.

Early receptor potential: photoreversible charge displacement in rhodopsin.

When the eye is illuminated by an intense flash, the visual pigment rhodopsin begins to pass rapidly through a series of intermediate states, eventually becoming bleached. If a second flash is delivered during the lifetimes of these intermediates the rhodopsin can be photoregenerated. A fast electrical response of the visual receptors, the early receptor potential, is elicited by the first flash. A similar response is elicited by the second flash, but the polarity of this response is reversed. Moreover, this response can be separated into three components, each arising from the action of light on a different intermediate. It is likely that all these fast responses, including the early receptor potential, arise from charge displacements in the visual-pigment molecule.

Polarization of fucoid eggs by a calcium ionophore gradient.

When the eggs of the brown alga Pelvetia were grown in a gradient of the calcium ionophore A23187, they tended to form their rhizoidal outgrowths on the sides that were exposed to the higher concentration of ionophore. This result supports the hypothesis that the formation of an intracellular calcium gradient is an essential step in the polarization of these eggs; the rhizoid forms at the pole that has the higher concentration of calcium.

Limulus rhodopsin: rapid return of transient intermediates to the thermally stable state.

Spectral transitions of rhodopsin in single cells of the Limulus ventral eye were observed both with flash photometry and by measuring the early receptor potential. Even with repetitive stimulus flashes the rhodopsin did not bleach; after each flash the spectral intermediates decayed rapidly to the initial thermally stable state. The pigment returns to the stable state in a time comparable with the duration of the late receptor potential.