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991.
Daniel Lucas José M. Delgado-García Beatriz Escudero Carmen Albo Ana Aza Rebeca Acín-Pérez Yaima Torres Paz Moreno José Antonio Enríquez Enrique Samper Luis Blanco Alfonso Fairén Antonio Bernad Agnès Gruart 《PloS one》2013,8(1)
A definitive consequence of the aging process is the progressive deterioration of higher cognitive functions. Defects in DNA repair mechanisms mostly result in accelerated aging and reduced brain function. DNA polymerase µ is a novel accessory partner for the non-homologous end-joining DNA repair pathway for double-strand breaks, and its deficiency causes reduced DNA repair. Using associative learning and long-term potentiation experiments, we demonstrate that Polµ−/− mice, however, maintain the ability to learn at ages when wild-type mice do not. Expression and biochemical analyses suggest that brain aging is delayed in Polµ−/− mice, being associated with a reduced error-prone DNA oxidative repair activity and a more efficient mitochondrial function. This is the first example in which the genetic ablation of a DNA-repair function results in a substantially better maintenance of learning abilities, together with fewer signs of brain aging, in old mice. 相似文献
992.
Sikorski J Teshima H Nolan M Lucas S Hammon N Deshpande S Cheng JF Pitluck S Liolios K Pagani I Ivanova N Huntemann M Mavromatis K Ovchinikova G Pati A Tapia R Han C Goodwin L Chen A Palaniappan K Land M Hauser L Ngatchou-Djao OD Rohde M Pukall R Spring S Abt B Göker M Detter JC Woyke T Bristow J Markowitz V Hugenholtz P Eisen JA Kyrpides NC Klenk HP Lapidus A 《Standards in genomic sciences》2011,4(3):331-341
Mahella australiensis Bonilla Salinas et al. 2004 is the type species of the genus Mahella, which belongs to the family Thermoanaerobacteraceae. The species is of interest because it differs from other known anaerobic spore-forming bacteria in its G+C content, and in certain phenotypic traits, such as carbon source utilization and relationship to temperature. Moreover, it has been discussed that this species might be an indigenous member of petroleum and oil reservoirs. This is the first completed genome sequence of a member of the genus Mahella and the ninth completed type strain genome sequence from the family Thermoanaerobacteraceae. The 3,135,972 bp long genome with its 2,974 protein-coding and 59 RNA genes is a part of the Genomic Encyclopedia of Bacteria and Archaea project. 相似文献
993.
The interplay between event and background sedimentation and the origin of fossil‐rich carbonate concretions: a case study in Permian rocks of the Paraná Basin,Brazil 下载免费PDF全文
João G. Bondioli Suzana A. Matos Lucas V. Warren Mário L. Assine Cláudio Riccomini Marcello G. Simões 《Lethaia: An International Journal of Palaeontology and Stratigraphy》2015,48(4):522-539
The Permian Serra Alta Formation was generated under transgressive conditions within a large, calm epeiric sea. A monotonous succession of ‘barren’, massive mudstones deposited under oxygen‐deficient conditions (mainly below storm wave base) is the main lithofacies of this unit. Fossils are generally rare and diluted in the matrix, but certain intervals contain shell‐rich concentrations with well‐preserved, closed articulated bivalves, mixed with shells and comminuted debris with variable quality of preservation, all encased in carbonate concretions. Two main scenarios may account for the origin of these bivalve‐rich concretions (i.e. unique events in sea‐water chemistry or unique burial‐starvation couplets). Sedimentological and taphonomic information indicates that the final deposition of the original shell‐rich mudstone intervals was probably tied to episodic influx of fine‐grained sediments in distal settings. Moderate bioturbation is also recorded suggesting low rates of sedimentation prior to early diagenesis. Hence, the fossil concentrations in concretions were formed due to the interplay of event and background sedimentation. These are internally simple concentrations with complex depositional histories. The concretion‐bearing beds are not randomly distributed in the Serra Alta Formation. Rather, they are found in the sparsely fossiliferous offshore deposits of the basal to intermediate portions of the unit. Thus, the concretionary mudstone beds and associated deposits are preserved in particular intervals and can be tracked for kilometres. This indicates that the conditions essential for concretion development existed only at particular stratigraphical intervals. Finally, our study strongly corroborates the idea that concretions are critical sources of sedimentological, taphonomic and stratigraphical information. 相似文献
994.
Begoña Granadino Luiz O. F. Penalva Lucas Sánchez 《Molecular & general genetics : MGG》1996,250(1):89-96
Crosses betweenDrosophila melanogaster females andD. simulans males produce viable hybrid females, while males are lethal. These males are rescued if they carry theD. simulans Lhr gene. This paper reports that females of the wild-typeD. melanogaster population Staket do not produce viable hybrid males when crossed withD. simulans Lhr males, a phenomenon which we designate as the Staket phenotype. The agent responsible for this phenomenon was found to be the StaketX chromosome (X
mel
,Stk). Analysis of the Staket phenotype showed that it is suppressed by extra copies ofD. melanogaster rDNA genes and that theX
mel
,Stk chromosome manifests a weak bobbed phenotype inD. melanogaster X
mel
,Stk/0 males. The numbers of functional rDNA genes inX
mel
,Stk andX
mel
,y w (control) chromosomes were found not to differ significantly. Thus a reduction in rDNA gene number cannot account for the weak bobbedX
mel
,Stk phenotype let alone the Staket phenotype. The rRNA precursor molecules transcribed from theX
mel
,Stk rDNA genes seem to be correctly processed in both intraspecific (melanogaster) and interspecific (melanogaster-simulans) conditions. It is therefore suggested that theX
mel
,Stk rDNA genes are inefficiently transcribed in themelanogaster-simulans hybrids. 相似文献
995.
996.
Recent Findings in the Chemistry of Odorants from Four Baccharis Species and Their Impact as Chemical Markers 下载免费PDF全文
Manuel Minteguiaga Noelia Umpiérrez Vanessa Xavier Aline Lucas Claudio Mondin Laura Fariña Eduardo Cassel Eduardo Dellacassa 《化学与生物多样性》2015,12(9):1339-1348
Baccharis is a widespread genus belonging to the Asteraceae family that includes almost 400 species exclusively from the Americas. Even when studied in detail, the taxonomic classification among species from this genus is not yet fully defined. Within the framework of our study of the volatile composition of the Baccharis genus, four species (B. trimera, B. milleflora, B. tridentata, and B. uncinella) were collected from the ‘Campos de Cima da Serra’ highlands of the Brazilian state of Rio Grande do Sul. The aerial parts were dried and extracted by the simultaneous distillation extraction (SDE) procedure. This is the first time that SDE has been applied to obtain and compare the volatile‐extract composition in the Baccharis genus. Characterization of the volatile extracts allowed the identification of 180 peaks with many coeluting components; these latter being detailed for the first time for this genus. The multivariate statistical analyses allowed separating the volatile extracts of the four populations of Baccharis into two separate groups. The first one included the B. milleflora, B. trimera, and B. uncinella volatile extracts. The three species showed a high degree of similarity in their volatile composition, which was characterized by the presence of high contents of sesquiterpene compounds, in particular of spathulenol. The second group comprised the extract of B. tridentata, which contained α‐pinene, β‐pinene, limonene, and (E)‐β‐ocimene in high amounts. 相似文献
997.
998.
Polymorphonuclear leukocyte-mediated, antibody-dependent, cellular cytotoxicity against tumor cells: dependence on oxygen and the respiratory burst. 总被引:10,自引:0,他引:10
Experiments were done to determine 1) whether the respiratory burst of superoxide anion (O2-) production in polymorphonuclear leukocytes (PMN) is triggered during antibody-dependent killing of tumor cells and 2) whether O2- production is essential for cytotoxicity. Three parameters of the respiratory burst (1-14C-glucose oxidation, oxygen consumption, and O2- release) were increased 2.5- to 7.3-fold during killing of antibody-primed tumor cells by human PMN. Added catalase and superoxide dismutase did not inhibit lysis, possibly because these enzymes were unable to diffuse into the inter-plasma-membrane space between killer and target cells. Evidence for an O2- requirement for cytotoxicity was the fact that concentrations of amobarbital or phenylbutazone sufficient to inhibit the cyanide-insensitive respiration of PMN also inhibited cytotoxicity. Also, hypoxic conditions inhibited cytotoxicity from 29 to 73%. The requirement for oxygen was most likely related to O2- generation and not mitochondrial respiration since cyanide and azide, which inhibit mitochondrial respiration, increased cytotoxicity. 相似文献
999.
L. Watrin S. Lucas C. Purcarea C. Legrain D. Prieur 《Molecular & general genetics : MGG》1999,262(2):378-381
Uracil auxotrophic mutants of the hyperthermophilic archaeon Pyrococcus abyssi were isolated by screening for resistance to 5-fluoro-orotic acid (5-FOA). Wild-type strains were unable to grow on medium
containing 5-FOA, whereas mutants grew normally. Enzymatic assays of extracts from wild-type P. abyssi and from pyrimidine auxotrophs demonstrated that the mutants are deficient in orotate phosphoribosyltransferase (PyrE) and/or
orotidine-5′-monophosphate decarboxylase (PyrF) activity. The pyrE gene of wild-type P. abyssi and one of its mutant derivatives were cloned and sequenced. This pyrE gene could serve as selectable marker for the development of gene manipulation systems in archaeal hyperthermophiles.
Received: 29 March 1999 / Accepted: 25 May 1999 相似文献
1000.
Oral Antibiotic Treatment of Mice Exacerbates the Disease Severity of Multiple Flavivirus Infections