MacroH2A1.1 regulates mitochondrial respiration by limiting nuclear NAD+ consumption

Histone variants are structural components of eukaryotic chromatin that can replace replication-coupled histones in the nucleosome. The histone variant macroH2A.1.1 contains a macrodomain able to bind NAD+ derived metabolites. Here, we report that macroH2A.1.1 is rapidly induced during myogenic differentiation through a switch in alternative splicing. Importantly, myotubes lacking macroH2A.1.1 display a defect in mitochondrial respiratory capacity. We find that the metabolite-interacting macrodomain is essential for sustaining optimal mitochondrial function, but dispensable for gene regulation. Through direct binding, macroH2A.1.1 inhibits basal poly-ADP ribose polymerase 1 activity and thus reduces nuclear NAD+ consumption. Consequentially, accumulation of the NAD+ precursor NMN allows the maintenance of mitochondrial NAD+ pools critical for respiration. Our data indicate that macroH2A.1.1-containing chromatin regulates mitochondrial respiration by limiting nuclear NAD+ consumption and establishing a buffer of NAD+ precursors in differentiated cells

Navika tjelesne aktivnosti kod autora koji su objavljivali u Hrvatskom časopisu za javno zdravstvo

Navike se mogu definirati kao stečeni oblik ponašanja. Navike nastaju višestrukim, višegodišnjim, ponavljanjem odgovarajućih pokreta ili radnji. Postoje razne vrste navika npr. navike ponašanja, higijenske navike, radne navike itd. Neke od njih su pozitivne, a neke negativne. Tjelesna aktivnost je primjer pozitivne navike, koja pridonosi poboljšanju psiho-fizičkog stanja čovjeka, te je stog vrlo važna u primarnoj prevenciji niza kroničnih i akutnih bolesti. Da bi se stvorila navika redovitog tjelesnog vježbanja potrebno je, unatoč fizičkom zamoru koji proizlazi iz same aktivnosti, ponavljati odgovarajuće vježbe ili aktivnosti iz dana u dan, iz godine u godinu. Kada organizam počne prepoznavati umor u vrijeme treninga, a pogotovo nakon treninga, kao vrhunac ugode, tada možete biti sigurni da ste ovisnik o jednoj pozitivnoj navici- tjelesnoj aktivnosti.

Navika tjelesne aktivnosti kod autora koji su objavljivali u Hrvatskom časopisu za javno zdravstvo

Navike se mogu definirati kao stečeni oblik ponašanja. Navike nastaju višestrukim, višegodišnjim, ponavljanjem odgovarajućih pokreta ili radnji. Postoje razne vrste navika npr. navike ponašanja, higijenske navike, radne navike itd. Neke od njih su pozitivne, a neke negativne. Tjelesna aktivnost je primjer pozitivne navike, koja pridonosi poboljšanju psiho-fizičkog stanja čovjeka, te je stog vrlo važna u primarnoj prevenciji niza kroničnih i akutnih bolesti. Da bi se stvorila navika redovitog tjelesnog vježbanja potrebno je, unatoč fizičkom zamoru koji proizlazi iz same aktivnosti, ponavljati odgovarajuće vježbe ili aktivnosti iz dana u dan, iz godine u godinu. Kada organizam počne prepoznavati umor u vrijeme treninga, a pogotovo nakon treninga, kao vrhunac ugode, tada možete biti sigurni da ste ovisnik o jednoj pozitivnoj navici- tjelesnoj aktivnosti.

Application of carbon fiber microelectrodes in electrochemical investigations

In this work, the electrocrystallization of nickel from Ni2+ -acidic bath has been investigated using an assembly of carbon fiber microelectrodes, consisting of single and multi microdics randomly distributed inside the matrix of a non-conducting polymer. The microdiscs were far enough apart that the crystals could not interact, thus limiting the total observed current density to a linear superposition of the current densities from each crystal considered independently. The current-time transient response was quantitatively evaluated using the Scharifker and Hills' nucleation model. The high rate of nucleation after a rapid increase in the overpotential was discussed in relation to the physical model for three-dimensional (3D) nucleation with diffusion-controlled growth. Excellent agreement between the experimental results and the theoretical curve for 3D progressive nucleation was obtained

PARP, transcription and chromatin modeling

Compaction mode of chromatin and chromatin highly organised structures regulate gene expression. Posttranslational modifications, histone variants and chromatin remodelers modulate the compaction, structure and therefore function of specific regions of chromatin. The generation of poly(ADP-ribose) (PAR) is emerging as one of the key signalling events on sites undergoing chromatin structure modulation. PAR is generated locally in response to stresses. These include genotoxic stress but also differentiation signals, metabolic and hormonal cues. A pictures emerges in which transient PAR formation is essential to orchestrate chromatin remodelling and transcription factors allowing the cell to adapt to alteration in its environment. This review summarizes the diverse factors of ADP-ribosylation in the adaptive regulation of chromatin structure and transcription

PARP, transcription and chromatin modeling

Compaction mode of chromatin and chromatin highly organised structures regulate gene expression. Posttranslational modifications, histone variants and chromatin remodelers modulate the compaction, structure and therefore function of specific regions of chromatin. The generation of poly(ADP-ribose) (PAR) is emerging as one of the key signalling events on sites undergoing chromatin structure modulation. PAR is generated locally in response to stresses. These include genotoxic stress but also differentiation signals, metabolic and hormonal cues. A pictures emerges in which transient PAR formation is essential to orchestrate chromatin remodelling and transcription factors allowing the cell to adapt to alteration in its environment. This review summarizes the diverse factors of ADP-ribosylation in the adaptive regulation of chromatin structure and transcription

Dissolution and storage stability of nanostructured calcium carbonates and phosphates for nutrition

Rapid calcium (Ca) dissolution from nanostructured Ca phosphate and carbonate (CaCO3) powders may allow them to be absorbed in much higher fraction in humans. Nanosized Ca phosphate and CaCO3 made by flame-assisted spray pyrolysis were characterized by nitrogen adsorption, X-ray diffraction (XRD), Raman spectroscopy, and transmission electron microscopy. As-prepared nanopowders contained both CaCO3 and CaO, but storing them under ambient conditions over 130 days resulted in a complete transformation into CaCO3, with an increase in both crystal and particle sizes. The small particle size could be stabilized against such aging by cation (Mg, Zn, Sr) and anion (P) doping, with P and Mg being most effective. Calcium phosphate nanopowders made at Ca:P ≤ .5 were XRD amorphous and contained γ-Ca2P2O7 with increasing hydroxyapatite content at higher Ca:P. Aging of powders with Ca:P = 1.0 and 1.5 for over 500 days gradually increased particle size (but less than for CaCO3) without a change in phase composition or crystallinity. In 0.01 M H3PO4 calcium phosphate nanopowders dissolved ≈4 times more Ca than micronsized compounds and about twice more Ca than CaCO3 nanopowders, confirming that nanosizing and/or amorphous structuring sharply increases Ca powder dissolution. Because higher Ca solubility in vitro generally leads to greater absorption in vivo, these novel FASP-made Ca nanostructured compounds may prove useful for nutrition applications, including supplementation and/or food fortification.ISSN:1388-0764ISSN:1572-896

Trichoscapa Karawajewi and its Synonyms (Hymenoptera: Formicidae)

A recent loan fom the Zoological Institute, Ukrainian Academy of Sciences, Kiev, Ukrainia, through the kindness of Dr. Alexander G. Radchenko, has allowed me for the first time to examine the type of Strumigenys emeryi Karawajew, which proves to be an example of the same species I later described as Smithistruma dubia. Since S. emeryi was preoccupied in Strumigenys, I had already given it the replacement name Strumigenys (Trichoscapa) karawajewi. The necessary synonymy follows

Chemical composition but not specific surface area affects calcium retention of nanostructured calcium compounds in growing rats

Background: Low dietary calcium intake and bioavailability may adversely affect bone health. Reducing the size of calcium compounds increases their specific surface area (SSA, expressed as m2/g) and may increase calcium dissolution and bioavailability. Objective: We investigated the influence of SSA and chemical composition on the bioavailability of calcium and compared in vitro calcium dissolution with in vivo absorption. Methods: Calcium dissolution was measured in 0.1 M phosphoric acid, whereas color and pH changes of foods were assessed as indicators for potential sensory performance. Calcium absorption, retention, and fractional retention were measured over a 5-d balance study in growing Sprague-Dawley male rats after 21 d of feeding. Femoral and vertebral bone mineral density (BMD) and extensive tissue histology were assessed at study end. The influence of SSA on calcium bioavailability was assessed by comparing the groups fed pure calcium carbonate (CaCO3) with increasing SSAs of 3, 36, and 64 m2/g (CaCO3_3, CaCO3_36 and CaCO3_64), whereas chemical composition was assessed by comparing the smallest CaCO3_64, a 50:50 wt:wt percent solution mixture of CaCO3 and hydroxyapatite_94, and pure hydroxyapatite_100. Results: In vivo, fractional calcium retention from hydroxyapatite_100 (mean ± SEM: 54.86% ± 0.95%/5 d) was significantly greater than from CaCO3_64 (49.66% ± 1.15%/5 d) (P = 0.044). Increasing SSA of the pure CaCO3 did not significantly improve calcium retention. Across all 5 groups, there were no significant differences in BMD or tissue calcification by histology. In vitro calcium dissolution did not correlate with SSA or calcium absorption. In selected food matrixes, hydroxyapatite_100 caused less color change and/or smaller pH increase than did the other calcium compounds. Conclusions: Our findings suggest that chemical composition rather than SSA is a predictor of nanostructured calcium bioavailability and that in vitro dissolution of nanostructured calcium does not predict in vivo absorption. Although its phosphorus content may limit use in some populations, nanostructured hydroxyapatite may be a promising calcium compound for food fortification