119 research outputs found

    On the change of old neutron star masses with galactocentric distance

    Full text link
    We show that the pulsar mass depends on the environment, and that it decreases going towards the center of the Milky Way. This is due to two combined effects, the capture and accumulation of self-interacting, non-annihilating dark matter by pulsars, and the increase of the dark matter density going towards the galactic center. We show that mass decrease depends both on the density profile of dark matter, steeper profiles producing a faster and larger decrease of the pulsar mass, and on the strength of self-interaction. Once future observations will provide the pulsar mass in a dark matter rich environment, close to the galactic center, the present result will be able to put constraints on the characteristics of our Galaxy halo dark matter profile, on the nature of dark matter, namely on its annihilating or non-annihilating nature, on its strength of self-interaction, and on the particle mass.Comment: 30pp 2fig

    cAMP promotes the synthesis in early G1 of gp115, a yeast glycoprotein containing glycosyl-phosphatidylinositol.

    Get PDF
    The glycoprotein gp115 (Mr = 115,000, pI 4.8-5) is localized in the plasma membrane of Saccharomyces cerevisiae cells and maximally expressed during G1 phase. To gain insight on the mechanism regulating its synthesis, we have examined various conditions of cell proliferation arrest. We used pulse-labeling experiments with [35S]methionine and two-dimensional gel electrophoresis analysis, which allow the detection of the well characterized 100-kDa precursor of gp115 (p100). In the cAMP-requiring mutant cyr1, p100 synthesis is active during exponential growth, shut off by cAMP removal, and induced when growth is restored by cAMP readdition. The inhibition of p100 synthesis also occurs in TS1 mutant cells (ras1ras2-ts1) shifted from 24 to 37 degrees C. During nitrogen starvation of rca1 cells, a mutant permeable to cAMP, p100 synthesis is also inhibited. cAMP complements the effect of ammonium deprivation, promoting p100 synthesis, even when added to cells which have already entered G0. Experiments with the bcy1 and cyr1bcy1 mutants have indicated the involvement of the cAMP-dependent protein kinases in the control of p100 synthesis. Moreover, the synthesis of p100 was unaffected in A364A cells, terminally arrested at START B by alpha-factor. These results indicate that the switch operating on p100 synthesis is localized in early G1 (START A) and is one of the multiple events controlled by the cAMP pathway

    Isolation and deduced amino acid sequence of the gene encoding gp115, a yeast glycophospholipid-anchored protein containing a serine-rich region.

    Get PDF
    Abstract gp115 is a N- and O-glycosylated protein of Saccharomyces cerevisiae. It is also modified by addition of glycosylphosphatidylinositol, which anchors the protein to the plasma membrane. The gene encoding gp115 (GGP1) has been cloned by a two-step procedure. By an immunoscreening of a yeast genomic DNA library in the expression vector lambda gt11, a 3'-terminal 0.9-kilobase portion of the gene has been isolated and then used as a molecular probe to screen a yeast genomic DNA library in YEp24. In this way, the whole GGP1 gene has been cloned. Its identity with the gp115 gene has been confirmed by gene disruption, which has also indicated that the function of gp115 is not essential for cell viability. The features of the sequence are also entirely consistent with it corresponding to the gp115 gene. The nucleotide sequence of GGP1 predicts a 60-kDa polypeptide, in agreement with the molecular mass of the gp115 precursor detected in sec53 mutant cells at restrictive temperature. Two hydrophobic sequences, one NH2- and the other COOH-terminal were found. The former has the features of the cleavable signal sequence, which allows the entry of proteins in the secretory pathway. The latter could be the signal sequence that has to be removed during the addition of glycosylphosphatidylinositol. The predicted amino acid sequence of gp115 shows 10 sequons for N-glycosylation and a high proportion of serine-threonine residues (22%) that could provide several sites for O-glycosylation. The unusual concentration of 27 serines in the COOH-terminal portion of the protein shares homology with a similar polyserine repeat of the serine repeat antigen (SERA protein) of Plasmodium falciparum. A two-dimensional analysis of the "in vitro" translational product of the GGP1 mRNA has been carried out, allowing the identification of the "in vivo" gp115 precursor in a two-dimensional gel

    O-linked oligosaccharides in yeast glycosyl phosphatidylinositol-anchored protein gp115 are clustered in a serine-rich region not essential for its function

    Get PDF
    Abstract The protein gp115 is an exocellular yeast glycoprotein modified by O- and N-glycosylation and attached to the plasma membrane through a glycosylphosphatidylinositol. The more remarkable structural feature in gp115 is the presence of a 36-amino acid serine-rich region. Similar sequences have been found in mammalian glycoproteins, such as the low density lipoprotein receptor, the decay-accelerating factor, and the mucins, where they are targets of multiple sites of O-glycosylation. The modification of these regions greatly influences their conformation and gives rise to "rodlike" structures. In this work, we have deleted or duplicated the Ser-rich region of gp115. The analysis of the size and glycosylation state of both mutant proteins indicates that about 52% of the total contribution of the O-glycosylation to the mass of the protein is concentrated in this region. The phenotype of ggp1 null mutant expressing the mutant proteins was also analyzed to understand if this region is important for gp115 function. The defects of slow growth rate and resistance to zymolyase of the ggp1 cells are completely complemented by both mutant proteins, suggesting that this region could be dispensable for gp115 function. A tentative model of gp115 structure is presented on the basis of the obtained data

    γEpithelial Na+ Channel and the Acid-Sensing Ion Channel 1 expression in the urothelium of patients with neurogenic detrusor overactivity

    Get PDF
    Both Epithelial Na+ Channel (γENaC) and the Acid-Sensing Ion Channel 1 (ASIC1) belong to Degenerin/Epithelial Na+ channel family that represents a new class of cation channels [1]. Increasing evidences show an involvement of these channels in the control of bladder afferent excitability under physiological and pathological conditions [2]; however, data available on their expression in human urothelium are controversial. Pathogenesis of the neurogenic detrusor overactivity (NDO), one of the most severe disabilities reported in patients with spinal cord lesions (SCL), has been attributed to bladder afferent dysfunction. Therefor, the aim of the present study was to investigate the expression of γENaC and ASIC1 in control urothelium and NDO patients. Controls and SCL patients with a clinical diagnosis of NDO underwent to urodynamic measurements and cystoscopy. Cold cup biopsies were processed for immunohistochemistry and western blots. In controls, γENaC and ASIC1 were expressed in the urothelium with different cell distribution and intensity. In NDO patients, both markers showed consistent changes in their cell distribution and intensity. Moreover, a significant correlation between the higher intensity of γENaC expression in urothelium of NDO patients and lower values of bladder compliance was found. In conclusion, the present findings show important changes in the expression of γENaC and ASIC1 in NDO human urothelium. Of note, while the changes in γENaC might impair the mechanosensory function of urothelium, the increase of the ASIC1 might represent an attempt to compensate excess in local sensitivity

    Le disfunzioni metacognitive nei disturbi di personalit Una review delle ricerche del III Centro di Psicoterapia Cognitiva

    Get PDF
    Dagli anni '90, il III Centro di Psicoterapia Cognitiva di Roma si è impegnato nell'attività clinica e di ricerca sul trattamento di pazienti gravi e difficili da trattare. In questo lavoro verranno analizzati alcuni tra i più importanti lavori pubblicati dal Gruppo in questo ambito. Si tratta di ricerche sul processo terapeutico condotte a partire dall’osservazione clinica secondo cui la presenza di specifici malfunzionamenti metacognitivi ostacolerebbe la costruzione della rappresentazione degli stati mentali propri e altrui; la regolazione della relazione terapeutica potrebbe migliorare tali malfunzionamenti rendendo così possibili gli interventi sugli aspetti sintomatici del paziente. Sono state portate, quindi, prove sufficienti a sostenere che la metacognizione sia una grandezza composta da sottofunzioni distinte semi-indipendenti. Altri studi del Gruppo hanno mostrato poi come la realtà clinica del paziente grave sia influenzata in modo diverso dalla presenza di specifici malfunzionamenti metacognitivi

    Poacic acid, a β‐1,3‐glucan–binding antifungal agent, inhibits cell‐wall remodeling and activates transcriptional responses regulated by the cell‐wall integrity and high‐osmolarity glycerol pathways in yeast

    Get PDF
    As a result of the relatively few available antifungals and the increasing frequency of resistance to them, the development of novel antifungals is increasingly important. The plant natural product poacic acid (PA) inhibits β-1,3-glucan synthesis in Saccharomyces cerevisiae and has antifungal activity against a wide range of plant pathogens. However, the mode of action of PA is unclear. Here, we reveal that PA specifically binds to β-1,3-glucan, its affinity for which is ~30-fold that for chitin. Besides its effect on β-1,3-glucan synthase activity, PA inhibited the yeast glucan-elongating activity of Gas1 and Gas2 and the chitin–glucan transglycosylase activity of Crh1. Regarding the cellular response to PA, transcriptional co-regulation was mediated by parallel activation of the cell-wall integrity (CWI) and high-osmolarity glycerol signaling pathways. Despite targeting β-1,3-glucan remodeling, the transcriptional profiles and regulatory circuits activated by caspofungin, zymolyase, and PA differed, indicating that their effects on CWI have different mechanisms. The effects of PA on the growth of yeast strains indicated that it has a mode of action distinct from that of echinocandins, suggesting it is a unique antifungal agent
    corecore