Melatonin modifies SOX2^+ cell proliferation in dentate gyrus and modulates SIRT1 and MECP2 in long-term sleep deprivation

Melatonin is a pleiotropic molecule that,after a short-term sleep deprivation,promotes the proliferation of neural stem cells in the adult hippocampus.However,this effect has not been observed in long-term sleep deprivation.The precise mechanism exerted by melatonin on the modulation of neural stem cells is not entirely elucidated,but evidence indicates that epigenetic regulators may be involved in this process.In this study,we investigated the effect of melatonin treatment during a 96-hour sleep deprivation and analyzed the expression of epigenetic modulators predicted by computational text mining and keyword clusterization.Our results showed that the administration of melatonin under sleep-deprived conditions increased the MECP2 expression and reduced the SIRT1 expression in the dentate gyrus.We observed that let-7 b,mir-132,and mir-124 were highly expressed in the dentate gyrus after melatonin administration,but they were not modified by sleep deprivation.In addition,we found more Sox2^+/5-bromo-2’-deoxyuridine(BrdU)^+cells in the subgranular zone of the sleep-deprived group treated with melatonin than in the untreated group.These findings may support the notion that melatonin modifies the expression of epigenetic mediators that,in turn,regulate the proliferation of neural progenitor cells in the adult dentate gyrus under long-term sleep-deprived conditions.All procedures performed in this study were approved by the Animal Ethics Committee of the University of Guadalajara,Mexico(approval No.CI-16610)on January 2,2016.

Catalysts for the hydrogen evolution reaction in alkaline medium:Configuring a cooperative mechanism at the Ag-Ag_(2)S-MoS_(2) interface

Designing electrocatalysts for HER in alkaline conditions to overcome the sluggish kinetics associated with the additional water dissociation step is a recognized challenge in promoting the hydrogen economy.To this end,delicately tuning the atomic-scale structure and surface composition of nanoparticles is a common strategy and,specifically,making use of hybrid structures,can produce synergistic effects that lead to highly active catalysts.Here,we present a core-shell catalyst of Ag@MoS_(2)that shows promising results towards the hydrogen evolution reaction(HER)in both 0.5 M H_(2)SO_(4)and 0.5 M KOH.In this hybrid structure,the MoS_(2)shell is strained and defective,and charge transfer occurs between the conductive core and the shell,contributing to the electrocatalytic activity.The shelling process results in a large fraction of Ag_(2)S in the cores,and adjusting the relative fractions of Ag,Ag_(2)S,and MoS_(2)leads to improved catalytic activity and fast charge-transfer kinetics.We suggest that the enhancement of alkaline HER is associated with a cooperative effect of the interfaces,where the Ag(Ⅰ)sites in Ag_(2)S drive the water dissociation step,and the formed hydrogen subsequently recombines on the defective MoS_(2)shell.This study demonstrates the benefits of hybrid structures as functional nanomaterials and provides a scheme to activate MoS_(2)for HER in alkaline conditions.

HP0953-hypothetical virulence factor overexpresion and localization during Helicobacter pylori infection of gastric epithelium

BACKGROUND The high prevalence and persistence of Helicobacter pylori(H. pylori) infection, as well as the diversity of pathologies related to it, suggest that the virulence factors used by this microorganism are varied. Moreover, as its proteome contains 340hypothetical proteins, it is important to investigate them to completely understand the mechanisms of its virulence and survival. We have previously reported that the hypothetical protein HP0953 is overexpressed during the first hours of adhesion to inert surfaces, under stress conditions, suggesting its role in the environmental survival of this bacterium and perhaps as a virulence factor.AIM To investigate the expression and localization of HP0953 during adhesion to an inert surface and against gastric(AGS) cells.METHODS Expression analysis was performed for HP0953 during H. pylori adhesion. HP0953 expression at 0,3, 12, 24, and 48 h was evaluated and compared using the Kruskal-Wallis equality-of-populations rank test. Recombinant protein was produced and used to obtain polyclonal antibodies for immunolocalization. Immunogold technique was performed on bacterial sections during adherence to inert surfaces and AGS cells, which was analyzed by transmission electron microscopy. HP0953 protein sequence was analyzed to predict the presence of a signal peptide and transmembrane helices, both provided by the ExPASy platform, and using the GLYCOPP platform for glycosylation sites. Different programs, via, I-TASSER, RaptorX, and HHalign-Kbest, were used to perform three-dimensional modeling.RESULTS HP0953 exhibited its maximum expression at 12 h of infection in gastric epithelium cells.Immunogold technique revealed HP0953 localization in the cytoplasm and accumulation in some peripheral areas of the bacterial body, with greater expression when it is close to AGS cells.Bioinformatics analysis revealed the presence of a signal peptide that interacts with the transmembrane region and then allows the release of the protein to the external environment. The programs also showed a similarity with the Tip-alpha protein of H. pylori. Tip-alpha is an exotoxin that penetrates cells and induces tumor necrosis factor alpha production, and HP0953 could have a similar function as posttranslational modification sites were found;modifications in turn require enzymes located in eukaryotic cells. Thus, to be functional, HP0953 may necessarily need to be translocated inside the cell where it can trigger different mechanisms producing cellular damage.CONCLUSION The location of HP0953 around infected cells, the probable posttranslational modifications, and its similarity to an exotoxin suggest that this protein is a virulence factor.

E-Cadherin Dysfunction and Cancer

E-cadherin molecules are cell-cell molecular connectors, but also act attaching cell surface to the cytoskeleton through catenin’s and additional partner proteins. Its main function is to regulate cellular adhesion and motility, and therefore acts as an invasion suppressor system. Its role is crucial in the induction and maintenance of cell polarity and differentiation, and in the organization and maintenance of tissue architecture. Downregulation or loss of its function is associated with an invasive and aggressive phenotype in many types of human cancers. In alterations of animal development, E-cadherin dysfunction influence in premature lethality or epidermal barrier and immunity defects. However, new hypothesis over its promoter role in tissue invasion is on focus. In addition to its tumor suppressor role, E-cadherin is a guiding molecule in collective cell migration increasing the metastasis risk during in vivo tumorigenesis. This E-cadherin function explains the retention of the functional E-cadherin expression, and that the epithelial-mesenchymal transition (EMT) is not required for the metastasis occurrence. However, like a switch, in some tumoral environments E-cadherin post-translational modifications may cause cell cluster migration. Like in development, in certain in vivo tumoral contexts, E-cadherin apparently involves signaling rather than cell contact formation. In this report, we explore the possibility of a novel role of thyroid hormones (THs) in the signal via E-cadherin-catenins, this not only should be involved in development and homeostasis, but also in cancer susceptibility of gastrointestinal tract.

Preliminary Study on Taxonomic Review Using Histological Sections of Some Iberian Species from the Genus <i>Quercus</i>L. (Fagaceae)

The taxonomy of the genus Quercus is the subject of ongoing scientific interest at the present time. Classically the scanning electron microscope is and has been used for the study of leaf surfaces, particularly to characterise the trichomes, stomata and epicuticular waxes. In the present work, in addition to using the SEM, histological sections from a group of taxa from the northern Iberian Peninsula are studied under the optical microscope. Specifically, the study concerns the leaves of Quercus robur subsp. robur, Q. orocantabrica, Q. petraea and Q. pyrenaica, and of possible hybrids between Q. orocantabrica and Q. petraea and between Q. orocantabrica and Q. pyrenaica. The results highlight histological differences between Q. robur and Q. orocantabrica, and also differentiate the morphological characteristics of Q. petraea and Q. pyrenaica. Similarities can also be observed between Q. petraea and its possible hybrid with Q. orocantabrica, and between Q. pyrenaica and its hybrid with Q. orocantabrica. The aspects observed under the optical microscope complement the observations obtained by means of the scanning electron microscope, and as a consequence of this, two new nothospecies are described: Q. xpuentei (Q. orocantabrica × Q. petraea) and Q. xpenasii (Q. orocantabrica × Q. pyrenaica).

Comparison of Chemical Elements on Carious &Normal Premolar’s Enamel Layers Using Energy Dispersive X Ray Spectrometer (X Ray-EDS)

Objectives: To compare the distribution of chemical elements among the carious and normal enamel layers on teenagers, using energy dispersive X ray spectrometer (EDS Rx). Materials and Methods: The EDS Rx analyzer is integrated to scanner electron microscope. The macro and mi-croelements were made in 30 premolars of teenager: 14 carious enamel layers and 16 normal enamel layers. Results: The quantitative and qualitative microanalyses of macro and microele-ments were found between the enamel layers of carious and normal premolar in term of variation and concentration expressed in percentage atomic weight. The statistical data analysis of ANOVA showed that the macroelements [C, Ca, P] and the microelements [Al, Cl, Mg, Na] were significantly different (P < 0.05) while, the macro [O] and the microelements [In, Si, W, S] were not significantly different (P < 0.05) among the carious and normal enamel layers. Moreover, the microelements Sb, Ba, Br, I, Ir, K, Pt, Sc, Sr, Sn and Yb were absent in carious enamel layers and present in normal enamel layers. Conclusion: The macro and microelements differ in composition and variation from the external to the internal enamel layers between the carious and the normal premolars. However, the deficiency or excess of these elements in the enamel layers determines the degree of susceptibility to carious and other dental disease. Clinical Relevance: The carious enamel in dental structure could be a major dental problem due to the deficiency or excess of macro and microele-ments which are responsible for secondary or recurrent caries, discoloration, pulpal inflammation, re-infection, abscess in jaw bone and dental disease.