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991.
Dedicado à Memória do Prof.Raffaele Ciferri 相似文献
992.
Mata Catarina van Vemde Nicole Clarkson David T. Martins-Loução Maria Amélia Lambers Hans 《Plant and Soil》2000,221(1):25-32
Nitrate influx, efflux and net nitrate uptake were measured for the slow-growing Quercus suber L. (cork-oak) to estimate the N-uptake efficiency of its seedlings when grown with free access to nitrate. We hypothesise
that nitrate influx, an energetically costly process, is not very efficiently controlled so as to avoid losses through efflux,
because Q. suber has relatively high respiratory costs for ion uptake. Q. suber seedlings were grown in a growth room in hydroponics with 1 mM NO3
-. Seedlings were labelled with 15NO3
- in nutrient solution for 5 min to measure influx and for 2 h for net uptake. Efflux was calculated as the difference between
influx and net uptake. Measurements were made in the morning, afternoon and night. The site of nitrate reduction was estimated
from the ratio of NO3
- to amino acids in the xylem sap; the observed ratio indicated that nitrate reduction occurred predominantly in the roots.
Nitrate influx was always much higher than net acquisition and both tended to be lower at night. High efflux occurred both
during the day and at night, although the proportion of 15NO3
- taken up that was loss through efflux was proportionally higher during the night. Efflux was a significant fraction of influx.
We concluded that the acquisition system is energetically inefficient under the conditions tested.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
993.
Ubiquinone (coenzyme Q10 or CoQ10) is a lipid-soluble component of virtually all cell membranes and has multiple metabolic functions. Deficiency of CoQ10 (MIM 607426) has been associated with five different clinical presentations that suggest genetic heterogeneity, which may
be related to the multiple steps in CoQ10 biosynthesis. Patients with all forms of CoQ10 deficiency have shown clinical improvements after initiating oral CoQ10 supplementation. Thus, early diagnosis is of critical importance in the management of these patients. This year, the first
molecular defect causing the infantile form of primary human CoQ10 deficiency has been reported. The availability of genetic testing will allow for a better understanding of the pathogenesis
of this disease and early initiation of therapy (even presymptomatically in siblings of patients) in this otherwise life-threatening
infantile encephalomyopathy.
Special issue dedicated to John P. Blass. 相似文献
994.
Background
Knowledge on fossil and evolutionary history of the Gnetales has expanded rapidly; Ephedra and ephedroids as well as the Gnetum-Welwitschia clade are now well documented in the Early Cretaceous. However, hypotheses on evolutionary relationships among living and fossil species are hampered by restricted knowledge of morphological variation in living groups and recent studies indicate that gnetalean diversity and character evolution may be more complex than previously assumed and involve additional extinct groups (Bennettitales, Erdtmanithecales and unassigned fossil taxa).Results
Here we describe a new fossil related to Gnetales, Siphonospermum simplex from the Early Cretaceous Yixian Formation, an impression/compression of a reproductive shoot. The slender main axis bears one pair of opposite and linear leaves with primary parallel venation. The reproductive units are ovoid, without supporting bracts and borne on one median and two lateral branches. The most conspicuous feature of the fossil is the long, thread-like micropylar tube formed by the integument. Each ovule is surrounded by two different layers representing one or two seed envelopes; an inner sclerenchymatous layer and an outer probably parenchymatous layer.Conclusions
The vegetative and reproductive features of Siphonospermum simplex exclude a relationship to any other group than the Gnetales. A combination of opposite phyllotaxis, linear leaves and ovules surrounded by seed envelope(s) and with a long exposed micropylar tube are known only for extant and extinct Gnetales. Siphonospermum simplex constitutes a new lineage within the Gnetales. Its morphology cannot be directly linked to any previously known plant, but the organization of the reproductive units indicates that it belongs to the Gnetum-Welwitschia clade. Based on the absence of cone bracts and the inferred histology of the seed envelope(s) it could be related to Gnetum, however, there are also affinities with the ephedran lineage, some of which are likely plesiomorphic features, others perhaps not. Phylogeny and character evolution in the Bennettitales, Erdtmanithecales and Gnetales are currently only partly understood and under debate; the exact systematic position of Siphonospermum simplex, i.e., its position within the Gnetales, cannot be resolved with certainty. 相似文献995.
Maria José Leandro Sara Cabral Catarina Prista Maria C. Loureiro-Dias Hana Sychrová 《Eukaryotic cell》2014,13(11):1371-1379
Zygosaccharomyces rouxii is a fructophilic yeast that consumes fructose preferably to glucose. This behavior seems to be related to sugar uptake. In this study, we constructed Z. rouxii single-, double-, and triple-deletion mutants in the UL4 strain background (a ura3 strain derived from CBS 732T) by deleting the genes encoding the specific fructose facilitator Z. rouxii Ffz1 (ZrFfz1), the fructose/glucose facilitator ZrFfz2, and/or the fructose symporter ZrFsy1. We analyzed the effects on the growth phenotype, on kinetic parameters of fructose and glucose uptake, and on sugar consumption profiles. No growth phenotype was observed on fructose or glucose upon deletion of FFZ genes. Deletion of ZrFFZ1 drastically reduced fructose transport capacity, increased glucose transport capacity, and eliminated the fructophilic character, while deletion of ZrFFZ2 had almost no effect. The strain in which both FFZ genes were deleted presented even higher consumption of glucose than strain Zrffz1Δ, probably due to a reduced repressing effect of fructose. This study confirms the molecular basis of the Z. rouxii fructophilic character, demonstrating that ZrFfz1 is essential for Z. rouxii fructophilic behavior. The gene is a good candidate to improve the fructose fermentation performance of industrial Saccharomyces cerevisiae strains. 相似文献
996.
Letícia Batista Soares Fabilene Gomes Paim Lucas Peres Ramos Fausto Foresti Claudio Oliveira 《Genetics and molecular biology》2021,44(2)
Hollandichthys is a fish genus of the family Characidae that was until recently considered to be monotypic, with cytogenetic, morphological, and molecular data being restricted to a few local populations. In the present study, the karyotype of a population of Hollandichthys multifasciatus was analyzed using classical and molecular cytogenetic approaches for the investigation of potential markers that could provide new perspectives on the cytotaxonomy. H. multifasciatus presented a diploid number of 2n=50 chromosomes and a karyotype formula of 8m+10sm+32st. A single pair of chromosomes presented Ag-NORs signals, which coincided with the 18S rDNA sites visualized by FISH, whilst the 5S rDNA sequences were mapped in two chromosome pairs. The distribution of the U snRNA genes was mapped on the Hollandichthys chromosomes for the first time, with the probes revealing the presence of the U1 snDNA on the chromosomes of pair 20, U2 on pairs 6 and 19, U4 on pair 16, and U6 on the chromosomes of pair 11. The results of the present study indicated karyotypic differences in comparison with the other populations of H. multifasciatus studied previously, reinforcing the need for further research to identify isolated populations or the potential existence of cryptic Hollandichthys species. 相似文献
997.
998.
999.
Jéssie Haigert Sudati Roselei Fachinetto Romaiana Picada Pereira Aline Augusti Boligon Margareth Linde Athayde Felix Antunes Soares Nilda Berenice de Vargas Barbosa João Batista Teixeira Rocha 《Neurochemical research》2009,34(8):1372-1379
Valeriana officinalis L. (Valerian) is widely used as a traditional medicine to improve the quality of sleep. Although V. officinalis have been well documented as promising pharmacological agent; the exact mechanisms by which this plant act is still unknown.
Limited literature data have indicated that V. officinalis extracts can exhibit antioxidant properties against iron in hippocampal neurons in vitro. However, there is no data available
about the possible antioxidant effect of V. officinalis against other pro-oxidants in brain. In the present study, the protective effect of V. officinalis on lipid peroxidation (LPO) induced by different pro-oxidant agents with neuropathological importance was examined. Ethanolic
extract of valerian (0–60 μg/ml) was tested against quinolinic acid (QA); 3-nitropropionic acid; sodium nitroprusside; iron
sulfate (FeSO4) and Fe2+/EDTA induced LPO in rat brain homogenates. The effect of V. officinalis in deoxyribose degradation and reactive oxygen species (ROS) production was also investigated. In brain homogenates, V. officinalis inhibited thiobarbituric acid reactive substances induced by all pro-oxidants tested in a concentration dependent manner.
Similarly, V. officinalis caused a significant decrease on the LPO in cerebral cortex and in deoxyribose degradation. QA-induced ROS production in
cortical slices was also significantly reduced by V. officinalis. Our results suggest that V. officinalis extract was effective in modulating LPO induced by different pro-oxidant agents. These data may imply that V. officinalis extract, functioning as antioxidant agent, can be beneficial for reducing insomnia complications linked to oxidative stress. 相似文献
1000.
Carlos Eduardo Braga de Abreu Gyedre dos Santos Araújo Ana Cristina de Oliveira Monteiro-Moreira José Hélio Costa Hugo de Brito Leite Frederico Bruno Mendes Batista Moreno José Tarquinio Prisco Enéas Gomes-Filho 《Plant cell reports》2014,33(8):1289-1306