138 research outputs found
Studies on the structure of hair-forming groups in Finnsheep
Recognition of hair-forming groups in the skin of sheep was dealt with by many scientists on almost all breeds of sheep in the world and in some particular countries. To the few breeds not yet investigated up to now in this respect belongs Finnsheep (F), and this substantiates the present attempt. The histological analysis was performed on skin sections taken by the biopsy method from 7 F of the Experiment Station Koluda Wielka. Upon fixing and staining skin preparations by the method generally applied, the microscopic examination of kinds of groups, number of primary (P) and secondary(S) follicles per 1 mm2 (nS/mm2 +nP/mm2) in all kinds of groups as well as density of follicles, i.e.nS/nP per 1 mm2, was carried out. In microscopic pictures of skin, documented by means of photographs, superiority of triple groups, the share of which amounted to 74.2 %, has been found. The share of quadruple groups was 11.4 %, of double groups 8.6 % and of hexal groups 5.1 %. The mean density of follicles, measured by the number of primary and secondary follicles per 1mm2 of skin, amounts to 14.1, which results from the share of 2.0 primary + 12.2 secondary follicles per 1 mm2. The value of the nS/nP ratio in particular groups was as follows: the highest ratio was for the triple group (6.0), in the double group it amounted to 5.8, in quadruple group to 5.6 and in the hexal group to 5.3. Thus, the mean density for this sheep breed amounts to 5.84. Differences in the above values between singles and groups appeared to be small and not proved statistically. The obtained results concerning the studied F skin traits are characteristics for the hair cover of longwoolled type
Back to the future: new techniques show that forgotten phosphorylation sites are present in contractile proteins of the heart whilst intensively studied sites appear to be absent
Protein kinase C α and ε phosphorylation of troponin and myosin binding protein C reduce Ca2+ sensitivity in human myocardium
Previous studies indicated that the increase in protein kinase C (PKC)-mediated myofilament protein phosphorylation observed in failing myocardium might be detrimental for contractile function. This study was designed to reveal and compare the effects of PKCα- and PKCε-mediated phosphorylation on myofilament function in human myocardium. Isometric force was measured at different [Ca2+] in single permeabilized cardiomyocytes from failing human left ventricular tissue. Activated PKCα and PKCε equally reduced Ca2+ sensitivity in failing cardiomyocytes (ΔpCa50 = 0.08 ± 0.01). Both PKC isoforms increased phosphorylation of troponin I- (cTnI) and myosin binding protein C (cMyBP-C) in failing cardiomyocytes. Subsequent incubation of failing cardiomyocytes with the catalytic subunit of protein kinase A (PKA) resulted in a further reduction in Ca2+ sensitivity, indicating that the effects of both PKC isoforms were not caused by cross-phosphorylation of PKA sites. Both isozymes showed no effects on maximal force and only PKCα resulted in a modest significant reduction in passive force. Effects of PKCα were only minor in donor cardiomyocytes, presumably because of already saturated cTnI and cMyBP-C phosphorylation levels. Donor tissue could therefore be used as a tool to reveal the functional effects of troponin T (cTnT) phosphorylation by PKCα. Massive dephosphorylation of cTnT with alkaline phosphatase increased Ca2+ sensitivity. Subsequently, PKCα treatment of donor cardiomyocytes reduced Ca2+ sensitivity (ΔpCa50 = 0.08 ± 0.02) and solely increased phosphorylation of cTnT, but did not affect maximal and passive force. PKCα- and PKCε-mediated phosphorylation of cMyBP-C and cTnI as well as cTnT decrease myofilament Ca2+ sensitivity and may thereby reduce contractility and enhance relaxation of human myocardium
Enzyme Promiscuity in Enolase Superfamily. Theoretical Study of o-Succinylbenzoate Synthase Using QM/MM Methods
The promiscuous activity of the enzyme o-succinylbenzoate synthase (OSBS) from the actinobacteria Amycolatopsis is investigated by means of QM/MM methods, using both density functional theory and semiempirical Hamiltonians. This enzyme catalyzes not only the dehydration of 2-succinyl-6R-hydroxy-2,4-cyclohexadiene-1R-carboxylate but also catalyzes racemization of different acylamino acids, with N-succinyl-R-phenylglycine being the best substrate. We investigated the molecular mechanisms for both reactions exploring the potential energy surface. Then, molecular dynamics simulations were performed to obtain the free energy profiles and the averaged interaction energies of enzymatic residues with the reacting system. Our results confirm the plausibility of the reaction mechanisms proposed in the literature, with a good agreement between theoretical and experimentally derived activation free energies. Our simulations unravel the role played by the different residues in each of the two possible reactions. The presence of flexible loops in the active site and the selection of structural modifications in the substrate seem to be key elements to promote the promiscuity of this enzyme.This work was supported by the Spanish Ministerio de Economia y Competitividad project CTQ2012-36253-C03-03 ́ and FEDER funds. K.S. thanks the Polish National Science Center (NCN) for Grant 2011/02/A/ST4/00246. The authors acknowledge computational facilities of the Servei d’Informatica ̀ de la Universitat de Valencia in the ̀ “Tirant” supercomputer, which is part of the Spanish Supercomputing Network
Unusual hydroxyl migration in the fragmentation of β-alanine dication in the gas phase
Transcendental-Phenomenological Proof and Descriptive Metaphysics
Following P.F. Strawson's reading of Kant, the majority of the literature on transcendental arguments seeks to divorce such arguments from their original Kantian context. This thesis is concerned with Mark Sacks's recent defence of transcendental arguments, which takes a different approach. A critique is given of Sacks's work and extensions and modifications of his approach are recommended. It is proposed that certain difficulties encountered by Kant's transcendentally-ideal approach can be overcome with Hegelian solutions
Mass spectrometric identification of oxidative modifications of tryptophan residues in proteins: Chemical artifact or post-translational modification?
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Electron induced dissociation in the condensed-phase nitromethane: II. Desorption of neurtral fragments
Low energy electron induced dissociation in multilayer films of nitromethane (CD3NO2) was investigated by high resolution electron energy loss spectroscopy (HREELS) and by the electron stimulated desorption (ESD) of neutral species. HREELS measurements show that the lowest electronic states of the condensed molecule are very similar to those seen in the gas phase. Desorbed neutrals were detected using combined non-resonant multi-photon ionization at 355 nm and time of flight mass spectrometry. The most intense signals detected were those of CD3 + and NO + and are attributed primarily to the desorption of CD3 and NO2 fragments following molecular dissociation via low-lying electronic excited states of nitromethane (the detected NO + being the result of the dissociative ionization of NO2). By varying the time delay between the incident electron pulse and the ionizing laser pulse, it is possible to measure the kinetic energy distributions of desorbing fragments. The kinetic energy distributions above ~ 5 eV appear invariant with incident electron energy, indicating that the same desorption process (dissociation via low-lying electronic states) operates at all the studied incident energies. Nevertheless, measurements of neutral yields as functions of incident electron energy demonstrate that excitation of the dissociative electronic states also proceeds via previously identified transient negative ions. At energies less than ~ 5 eV, contributions from dissociative electron attachment are also observed in the yield of CD3 and other neutral fragments
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