Primary cilia regulate proliferation of amplifying progenitors in adult hippocampus: implications for learning and memory

Integration of new neurons into the adult hippocampus has been linked to specific types of learning. Primary cilia were found to be required for the formation of adult neural stem cells (NSCs) in the hippocampal dentate gyrus during development. However, the requirement of cilia in maintenance of adult NSCs is unknown. We developed a genetic mouse model in which fetal/perinatal brain development is unaffected, but adult hippocampal neurogenesis is constantly reduced by conditional ablation of primary cilia in adult GFAP(+) neural stem/progenitor cells. We found that this approach specifically reduces the number of hippocampal amplifying progenitors (also called type 2a cells) without affecting the number of radial NSCs (or type 1 cells). Constant reduction of adult hippocampal neurogenesis produced a delay rather than a permanent deficiency in spatial learning without affecting the retention of long-term memories. Decreased neurogenesis also altered spatial novelty recognition and hippocampus-independent cue conditioning. Here, we propose that adult hippocampal newborn neurons increase the efficiency of generating the new representations of spatial memories and that reduction of adult hippocampal neurogenesis may be biased toward cue-based strategies. This novel mouse model provides evidences that cognitive deficits associated with ciliary defects (ciliopathies) might be, in part, mediated by the deficiency of primary cilia in adult hippocampal stem/progenitor cells

Effects of ammonium nitrate, cesium chloride and tetraethylammonium on high-affinity potassium uptake in habanero pepper plantlets (Capsicum chinense Jacq.)

Potassium (K+) is an essential nutrient and the most abundant cation in plant cells. Plants have a wide variety of transport systems for K+ acquisition that catalyze K+ uptake across a wide spectrum of external K+ concentrations and mediate K+ movement within the plant, as well as its release into the environment. The KUP/HAK/KT transporter family plays a key role in K+ homeostasis in plant cells. The present study demonstrates that habanero pepper plantlets have a clear pattern of K+ uptake when resupplemented with K+ after K+ starvation. Habanero pepper plantlets, re-supplemented with a solution containing low concentrations of K+ after 72, 96 or 120 h of K+ starvation were able to decrease the amount of K+ in the solution at different time points. To study the effect of NH4+, we added different concentrations of NH4NO3 to the medium solution and demonstrated that NH4+ inhibited K+ uptake in a dose-dependent manner. When the plantlets were subjected to K+ starvation for 72 h and then resupplemented with 50 or 100 μM K+, exposure to K+ channel blockers (10 mM CsCl and 20 mM TEA) decreased their K+ uptake compared with the control treatment. A model demonstrating the process of K+ uptake through an NH4+-insensitive component was proposed.Key words: Potassium, high affinity transporters, channel blockers, ammonium

Quantum squeezing of optical dissipative structures

We show that any optical dissipative structure supported by degenerate optical parametric oscillators contains a special transverse mode that is free from quantum fluctuations when measured in a balanced homodyne detection experiment. The phenomenon is not critical as it is independent of the system parameters and, in particular, of the existence of bifurcations. This result is a consequence of the spatial symmetry breaking introduced by the dissipative structure. Effects that could degrade the squeezing level are considered.Comment: 4 pages and a half, 1 fugure. Version to appear in Europhysics Letter

Quantum coherent control of highly multipartite continuous-variable entangled states by tailoring parametric interactions

The generation of continuous-variable multipartite entangled states is important for several protocols of quantum information processing and communication, such as one-way quantum computation or controlled dense coding. In this article we theoretically show that multimode optical parametric oscillators can produce a great variety of such states by an appropriate control of the parametric interaction, what we accomplish by tailoring either the spatio-temporal shape of the pump, or the geometry of the nonlinear medium. Specific examples involving currently available optical parametric oscillators are given, hence showing that our ideas are within reach of present technology.Comment: 14 pages, 5 figure

Coordination when there are restricted and unrestricted options

One might expect that, in pure coordination games, coordination would become less frequent as the number of options increases. Contrary to this expectation, we report an experiment which found more frequent coordination when the option set was unrestricted than when it was restricted. To try to explain this result, we develop a method for eliciting the general rules that subjects use to identify salient options in restricted and unrestricted sets. We find that each such rule, if used by all subjects, would generate greater coordination in restricted sets. However, subjects tend to apply different rules to restricted and unrestricted sets

Oral ulcer as an exclusive sign of gastric cancer: report of a rare case

BACKGROUND: The oral cavity is a rare but occasional target for metastases, which may masquerade as various benign and inflammatory lesions, and sometimes also be asymptomatic. Oral metastatic lesions have been described in various cancers, particularly lung, breast and kidney carcinoma. CASE PRESENTATION: We here describe an uncommon case of a hard palate mucosa and gingival metastasis from gastric carcinoma that was originally diagnosed as a periodontal disease. Histopathological examination of a biopsy of the lesion revealed a signet-ring cell carcinoma, and a subsequent biopsy of an ulcerated stomach lesion showed a poorly differentiated gastric carcinoma. The patient underwent gastric resection but died of heart failure on the tenth postoperative day; a post-mortem examination revealed a residual bilateral ovarian infiltration by gastric carcinoma (Krukenberg's tumor). CONCLUSION: An occult carcinoma of the stomach may rarely metastasise to the oral cavity even as a first and exclusive manifestation; it is important to bear this possibility in mind because such conditions may mimic a benign disease

High-Directional Wave Propagation in Periodic Gain/Loss Modulated Materials

Amplification/attenuation of light waves in artificial materials with a gain/loss modulation on the wavelength scale can be sensitive to the propagation direction. We give a numerical proof of the high anisotropy of the gain/loss in two dimensional periodic structures with square and rhombic lattice symmetry by solving the full set of Maxwell's equations using the finite difference time domain method. Anisotropy of amplification/attenuation leads to the narrowing of the angular spectrum of propagating radiation with wavevectors close to the edges of the first Brillouin Zone. The effect provides a novel and useful method to filter out high spatial harmonics from noisy beams

The Reintegration of Ex-Combatants and Post-Conflict Violence. An Analysis of Municipal Crime Levels in Colombia

Violent crime in Colombia is analyzed following the demobilization of ex-combatants using municipal-level data. The main findings are that an increased presence of ex-combatants does not systematically increase homicides, but may increase robberies. Reintegration programs are shown to matter. Former paramilitaries who are not in a reintegration program increase crime. Former guerillas increase robberies, regardless of whether they are in or out of reintegration, but homicides decrease for guerrillas in reintegration. Ex-combatants often settle in municipalities with more crime. Controlling for reverse causality, ex-combatants only increase crime if they are not in reintegration, while in reintegration they may reduce crime

Comparison of the web-based and digital questionnaires of the Spanish and Catalan versions of the KIDSCREEN-52

Background: The objectives of the study were to develop web-based Spanish and Catalan versions of the KIDSCREEN, and to compare scores and psychometric properties with the paper version. Methods: Internet and paper Spanish and Catalan versions of the KIDSCREEN-52 were included in a cross-sectional study in school-age children. Web-based and paper Spanish or Catalan versions of the KIDSCREEN-52 were administered to students aged 8 to 18 years from primary and secondary schools in Palafolls (Barcelona, Spain, n5923). All students completed both web-based and paper versions during school time with an interval of at least 2 hours between administrations. The order of administration was randomized. The KIDSCREEN-52, the Strengths and Difficulties Questionnaire (SDQ), and sociodemographic variables were collected. Missing values, floor and ceiling effects, and internal consistency were compared between both versions, as well as mean score differences, level of agreement, and known groups and construct validity. Results: Participation rate was 77% (n5715). Web-based and paper versions showed low percentage of missing values and similar high ceiling effect (range 0 to 44%). Mean score differences showed an effect size (ES) lower than 0.2 in all dimensions. Internal consistency ranged from 0.7 to 0.88, and degree of agreement was excellent (Intraclass correlation coefficient [ICC] range 0.75 to 0.87). Expected differences were seen by sex, age, socioeconomic status and mental health status. Conclusions: The web-based KIDSCREEN-52 showed similar scale score and reliability and validity than the paper version. It will incorporate the child population in the assessment of quality of life providing a more attractive format