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991.
Verstraeten VL Renes J Ramaekers FC Kamps M Kuijpers HJ Verheyen F Wabitsch M Steijlen PM van Steensel MA Broers JL 《Histochemistry and cell biology》2011,135(3):251-261
A thorough understanding of fat cell biology is necessary to counter the epidemic of obesity. Although molecular pathways
governing adipogenesis are well delineated, the structure of the nuclear lamina and nuclear-cytoskeleton junction in this
process are not. The identification of the ‘linker of nucleus and cytoskeleton’ (LINC) complex made us consider a role for
the nuclear lamina in adipose conversion. We herein focused on the structure of the nuclear lamina and its coupling to the
vimentin network, which forms a cage-like structure surrounding individual lipid droplets in mature adipocytes. Analysis of
a mouse and human model system for fat cell differentiation showed fragmentation of the nuclear lamina and subsequent loss
of lamins A, C, B1 and emerin at the nuclear rim, which coincides with reorganization of the nesprin-3/plectin/vimentin complex
into a network lining lipid droplets. Upon 18 days of fat cell differentiation, the fraction of adipocytes expressing lamins
A, C and B1 at the nuclear rim increased, though overall lamin A/C protein levels were low. Lamin B2 remained at the nuclear
rim throughout fat cell differentiation. Light and electron microscopy of a subcutaneous adipose tissue specimen showed striking
indentations of the nucleus by lipid droplets, suggestive for an increased plasticity of the nucleus due to profound reorganization
of the cellular infrastructure. This dynamic reorganization of the nuclear lamina in adipogenesis is an important finding
that may open up new venues for research in and treatment of obesity and nuclear lamina-associated lipodystrophy. 相似文献
992.
Patrícia M. Paes de Sousa Sofia R. Pauleta M. Lurdes Simões Gonçalves Graham W. Pettigrew Isabel Moura José J. G. Moura Margarida M. Correia dos Santos 《Journal of biological inorganic chemistry》2011,16(2):209-215
In this work it is demonstrated that the characterization of c-type haem containing proteins by electrochemical techniques needs to be cautiously performed when using pyrolytic graphite
electrodes. An altered form of the cytochromes, which has a redox potential 300 mV lower than that of the native state and
displays peroxidatic activity, can be induced by interaction with the pyrolytic graphite electrode. Proper control experiments
need to be performed, as altered conformations of the enzymes containing c-type haems can show activity towards the enzyme substrate. The work was focused on the study of the activation mechanism
and catalytic activity of cytochrome c peroxidase from Paracoccus
pantotrophus. The results could only be interpreted with the assignment of the observed non-turnover and catalytic signals to a non-native
conformation state of the electron-transferring haem. The same phenomenon was detected for Met–His monohaem cytochromes (mitochondrial
cytochrome c and Desulfovibrio
vulgaris cytochrome c-553), as well as for the bis-His multihaem cytochrome c
3 from Desulfovibrio
gigas, showing that this effect is independent of the axial coordination of the c-type haem protein. Thus, the interpretation of electrochemical signals of c-type (multi)haem proteins at pyrolytic graphite electrodes must be carefully performed, to avoid misassignment of the signals
and incorrect interpretation of catalytic intermediates. 相似文献
993.
Gutiérrez-Abad R Carbajo D Nolis P Acosta-Silva C Cobos JA Illa O Royo M Ortuño RM 《Amino acids》2011,41(3):673-686
Two diastereomeric series of hybrid γ,γ-peptides derived from conveniently protected derivatives of (1R,2S)- and (1S,2R)-3-amino-2,2-dimethylcyclobutane-1-carboxylic acid and cis-4-amino-l-proline joined in alternation have efficiently been prepared through convergent synthesis. High-resolution NMR experiments
show that these compounds present defined conformations in solution affording very compact structures as the result of intra
and inter residue hydrogen-bonded ring formation. (R,S)-cyclobutane containing peptides adopt more twisted conformations than (S,R) diastereomers. In addition, all these γ-peptides have high tendency to aggregation providing vesicles of nanometric size,
which were stable when allowed to stand for several days, as verified by transmission electron microscopy. 相似文献
994.
Nelo Eidy Zanchi Frederico Gerlinger-Romero Lucas Guimarães-Ferreira Mário Alves de Siqueira Filho Vitor Felitti Fabio Santos Lira Marília Seelaender Antonio Herbert LanchaJr. 《Amino acids》2011,40(4):1015-1025
Amino acids such as leucine and its metabolite α-ketoisocaproate (KIC), are returning to be the focus of studies, mainly because
of their anti-catabolic properties, through inhibition of muscle proteolysis and enhancement of protein synthesis. It is clear
that these effects may counteract catabolic conditions, as well as enhance skeletal muscle mass and strength in athletes.
Moreover, beta-hydroxy-beta-methylbutyrate (HMB) has been shown to produce an important effect in reducing muscle damage induced
by mechanical stimuli of skeletal muscle. This review aims to describe the general scientific evidence of KIC and HMB supplementation
clinical relevance, as well as their effects (e.g., increases in skeletal muscle mass and/or strength), associated with resistance
training or other sports. Moreover, the possible mechanisms of cell signaling regulation leading to increases and/or sparing
(during catabolic conditions) of skeletal muscle mass are discussed in detail based on the recent literature. 相似文献
995.
Adauto Lima Cardoso Julio Cesar Pieczarka Eliana Feldberg Susana Suely Rodrigues Milhomem Thiago Moreira-Almeida Danillo dos Santos Silva Patrícia Corrêa da Silva Cleusa Yoshiko Nagamachi 《Reviews in Fish Biology and Fisheries》2011,21(3):613-621
Gymnotiformes are an important component of the Neotropical ichthyofauna and they are known for their ability to generate
and detect electrical discharges. Phylogenetic relationships of Gymnotiformes are still not well understood. However, the
monophyly of the superfamily Rhamphichthyoidea is well accepted, despite the position of tribe Steatogenini (Steatogenys, Hypopygus and Stegostenopos) within this superfamily is unclear. The genus Steatogenys includes three species that, together with Hypopygus and Stegostenopos, form tribe Steatogenini. Cytogenetic information is currently only available for Hypopygus lepturus. Here, we describe the karyotypes of Steatogenys elegans from four localities and S. duidae from two localities. S. elegans was found to have 2n = 50, ZZ/ZW (12m-sm/38st-a), while S. duidae had 2n = 50 (50m-sm). In S. elegans, constitutive heterochromatin (CH) was observed in the centromeric regions of all chromosomes, in the interstitial region
of 1q, and in two blocks of Wq. In S. duidae, CH was observed in the centromeric and pericentromeric regions of all chromosomes, and in the interstitial regions of 2q,
3q, 5q, and 7q. Nucleolar organizer regions (NORs) were identified in the distal regions of one chromosome pair in each species.
The CMA3 fluorochrome (specific to G-C rich regions) coincided with the NORs in both species, and with the HC of S. elegans except on chromosome pair 5 and the W. The DAPI fluorochrome (specific to A-T rich regions) coincided with the CH of both
species, and was very intense for chromosome pair 5 and the W of S. elegans. Our observations suggest that the ZZ/ZW system observed in S. elegans likely evolved through CH addition followed by a paracentric inversion. The chromosomal data described herein are consistent
with the phylogenetic hypothesis that tribe Steatogenini should be positioned within family Ramphychthyidae. 相似文献
996.
Miriam Rosenbaum Federico Aulenta Marianna Villano Largus T. Angenent 《Bioresource technology》2011,102(1):324-333
This review illuminates extracellular electron transfer mechanisms that may be involved in microbial bioelectrochemical systems with biocathodes. Microbially-catalyzed cathodes are evolving for new bioprocessing applications for waste(water) treatment, carbon dioxide fixation, chemical product formation, or bioremediation. Extracellular electron transfer processes in biological anodes, were the electrode serves as electron acceptor, have been widely studied. However, for biological cathodes the question remains: what are the biochemical mechanisms for the extracellular electron transfer from a cathode (electron donor) to a microorganism? This question was approached by not only analysing the literature on biocathodes, but also by investigating known extracellular microbial oxidation reactions in environmental processes. Here, it is predicted that in direct electron transfer reactions, c-type cytochromes often together with hydrogenases play a critical role and that, in mediated electron transfer reactions, natural redox mediators, such as PQQ, will be involved in the bioelectrochemical reaction. These mechanisms are very similar to processes at the bioanode, but the components operate at different redox potentials. The biocatalyzed cathode reactions, thereby, are not necessarily energy conserving for the microorganism. 相似文献
997.
Enantiopure Ti(IV) complexes bearing pseudo-C(3) amino triphenolate ligands have been synthesized and characterized. The complexes bearing ortho phenyl groups act as (1)H NMR chiral solvating agent (CSA) for the stereochemical analysis of a series of sulfoxides. The coordination of a Lewis base coligand (sulfoxide) and the presence of aromatic rings are the key structural factors for the efficiency of the CSA. 相似文献
998.
This study investigated the effect of glow discharge treatment of titania surfaces on plasma protein adsorption, by means of ellipsometry and mechanically assisted SDS elution. The adsorption and film elution of three plasma proteins, viz. human serum albumin (HSA), human immunoglobulin G (IgG) and laminin-1, as well as competitive adsorption from a mixture of the three proteins, showed that the adsorbed amount of the individual proteins after 1 h increased in the order HSA 相似文献
999.
Plants defend themselves against biotic or abiotic stress by triggering intracellular signaling pathways that regulate gene expression and responses to the offending agent. Phosphorylation and dephosphorylation represent major mechanisms for the regulation of plant defense pathways. Therefore, MAP kinases and phosphatases have been the focus of many studies in this area. This study identified three phosphatase activities, namely RcPPase I, II and III. Wounding increased the activity levels of RcPPase III, while the activities of RcPPase I and II remained constant compared to the control. N-terminal partial amino acid sequence, biochemical characterization with use of specific substrates and inhibitors indicated that the RcPPase III belong to the family of tyrosine phosphatases (PTPs). 相似文献
1000.
Melo FH Molognoni F Morais AS Toricelli M Mouro MG Higa EM Lopes JD Jasiulionis MG 《Free radical biology & medicine》2011,50(10):1263-1273
Melanoma cell lines and cells corresponding to premalignant melanocytes were established by our group after subjecting a nontumorigenic murine melanocyte lineage, melan-a, to sequential cycles of anchorage blockade. Previous results showed that in melan-a cells the superoxide level increases after such procedure. Superoxide production during melanocyte de-adhesion was inhibited by L-sepiapterin, the precursor of eNOS cofactor BH4, and increased by the inhibitor of BH4 synthesis, DAHP, hence indicating a partial uncoupling state of eNOS. The eNOS uncoupling seems to be maintained in cells derived from melan-a, because they present decreased nitric oxide and increased superoxide levels. The inhibition of superoxide production in Tm5 melanoma cells with L-sepiapterin reinforces their eNOS-uncoupled state. The maintenance of oxidative stress seems to be important in melanoma apoptosis resistance because Mn(III)TBAP, a superoxide scavenger, or L-sepiapterin renders Tm5 cells more sensitive to anoikis and chemotherapy. More importantly, eNOS uncoupling seems to play a pivotal role in melanocyte malignant transformation induced by sustained anchorage impediment, because no malignant transformation was observed when L-NAME-treated melanocytes were subjected to sequential cycles of de-adhesion. Our results show that uncoupled eNOS contributes to superoxide production during melanocyte anchorage impediment, contributing to anoikis resistance and malignant transformation. 相似文献