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41.
Adrienn Guóth Dániel Benyó Jolán Csiszár Ágnes Gallé Ferenc Horváth László Cseuz László Erdei Irma Tari 《Acta Physiologiae Plantarum》2010,32(4):719-727
The effects of increasing osmotic stress induced by 100–400 mOsm (−0.976 MPa) polyethylene glycol (PEG 6000) were investigated
in a drought-tolerant (Triticum aestivum L. cv. Mv Emese) and drought-sensitive (cv. GK élet) wheat cultivar at the three-leaf stage. During osmotic stress, the decline
of the water potential (ψ
w) was more significant in the leaves, while the abscisic acid (ABA) levels of the roots increased earlier and remained higher
in the sensitive than in the tolerant variety. There was an increasing gradient of ABA content toward the youngest leaves
in the drought-sensitive GK élet, while more ABA accumulated in the fully developed, older leaves of the tolerant cultivar
Mv Emese. In accordance with the rapid and significant accumulation of ABA, the stomatal conductance decreased earlier in
the tolerant cultivar. The effect of water stress on the PSII photochemistry was pronounced only 1 week after the exposure
to PEG, as indicated by the earlier decrease of the net CO2 fixation, the effective quantum yield (ΦPSII) and the photochemical quenching (q
P) in light-adapted samples of the tolerant variety in 400 mOsm PEG 6000. The stress treatment caused more significant reductions
in these parameters toward the end of the experiment in the sensitive cultivar. In spite of small differences in the photosynthetic
characteristics, the net biomass production was not significantly altered by this osmotic stress. The accumulation of ABA
controlled the distribution of the biomass between the shoot and root systems under osmotic stress, and contributed to the
development of stronger and deeper roots in the drought-sensitive cultivar GK élet. However, the root elongation did not correlate
with the drought sensitivity of these cultivars on the basis of crop yield. 相似文献
42.
Cilurzo F Cupone IE Minghetti P Buratti S Selmin F Gennari CG Montanari L 《AAPS PharmSciTech》2010,11(4):1511-1517
This work aimed to develop a fast-dissolving film made of low dextrose equivalent maltodextrins (MDX) containing nicotine
hydrogen tartrate salt (NHT). Particular attention was given to the selection of the suitable taste-masking agent (TMA) and
the characterisation of the ductility and flexibility under different mechanical stresses. MDX with two different dextrose
equivalents (DEs), namely DE 6 and DE 12, were selected in order to evaluate the effect of polymer molecular weight on film
tensile properties. The bitterness and astringency intensity of NHT and the suppression effect of several TMA were evaluated
by a Taste-Sensing System. The films were characterised in term of NHT content, tensile properties, disintegration time and
drug dissolution test. As expected, placebo films made of MDX DE 6 appeared stiffer and less ductile than film prepared using
MDX DE 12. The films disintegrated within 10 s. Among the tested TMA, the milk and mint flavours resulted particularly suitable
to mask the taste of NHT. The addition of NHT and taste-masking agents affected film tensile properties; however, the effect
of the addition of these components can be counterweighted by modulating the glycerine content and/or the MDX molecular weight.
The feasibility of NHT loaded fast-dissolving films was demonstrated. 相似文献
43.
Cyclin A/Cdk2 plays an important role during S and G2/M phases of the eukaryotic cell cycle, but the mechanisms by which it regulates cell cycle events are not fully understood. We have biochemically purified and identified SCAPER, a novel protein that specifically interacts with cyclin A/Cdk2 in vivo. Its expression is cell cycle independent, and it associates with cyclin A/Cdk2 at multiple phases of the cell cycle. SCAPER localizes primarily to the endoplasmic reticulum. Ectopic expression of SCAPER sequesters cyclin A from the nucleus and results specifically in an accumulation of cells in M phase of the cell cycle. RNAi-mediated depletion of SCAPER decreases the cytoplasmic pool of cyclin A and delays the G1/S phase transition upon cell cycle re-entry from quiescence. We propose that SCAPER represents a novel cyclin A/Cdk2 regulatory protein that transiently maintains this kinase in the cytoplasm. SCAPER could play a role in distinguishing S phase- from M phase-specific functions of cyclin A/Cdk2. 相似文献
44.
Morales-Rodríguez I Yañez-Morales M Silva-Rojas HV García-de-Los-Santos G Guzmán-de-Peña DA 《Mycopathologia》2007,163(1):31-39
Fusarium
proliferatum, F. subglutinans, and F. verticillioides are known causes of ear and kernel rot in maize worldwide. In Mexico, only F. verticillioides and F. subglutinans, have been reported previously as causal agents of this disease. However, Fusarium isolates with different morphological characteristics to the species that are known to cause this disease were obtained in
the Highland-Valley region of this country from symptomatic and symptomless ears of native and commercial maize genotypes.
Moreover, while the morphological studies were not sufficient to identify the correct taxonomic position at the species level,
analyses based in the Internal Transcribed Spacer region and the Nuclear Large Subunit Ribosomal partial sequences allowed
for the identification of F. subglutinans, F. solani, and F. verticillioides, as well as four species (F. chlamydosporum, F. napiforme, F. poae, and F. pseudonygamai) that had not previously been reported to be associated with ear rot. In addition, F. napiforme and F. solani were absent from symptomless kernels. Phylogenetic analysis showed genetic changes in F. napiforme, and F. pseudonygamai isolates because they were not true clones, and probably constitute separate sibling species. The results of this study suggest
that the biodiversity of Fusarium species involved in ear rot in Mexico is greater than that reported previously in other places in the world. This new knowledge
will permit a better understanding of the relationship between all the species involved in ear rot disease and their relationship
with maize. 相似文献
45.
Viani FC Cazares Viani PR Gutierrez Rivera IN Gonçalves da Silva E Rodrigues Paula C Gambale W 《Revista iberoamericana de micología》2007,24(1):19-23
Microsporum canis is the main zoophylic dermatophyte in dogs and cats, and it is also an important zoonotic agent. The literature showed that cats are asymptomatic carriers of M. canis. This is apparently due to host resistance and/or the presence of strains with lower virulence. This study was aimed to evaluate the keratinolytic, elastinolytic and collagenolytic activities of M. canis strains and their relationship with symptomatic and asymptomatic cats. In addition, these strains were analysed by RFLP. The strains isolated from cats with clinical dermatophytosis had higher keratinase and elastase activity than those isolated from asymptomatic animals (p minus than 0.05). There were not differences in RFLP patterns based on Hind III digestion. 相似文献
46.
Hassan S Sainz IM Khan MM Bradford HN Isordia-Salas I Kashem SW Sartor RB Colman RW 《American journal of physiology. Heart and circulatory physiology》2007,292(6):H2959-H2965
High-molecular-weight kininogen (HK) and its domain 3 (D3) exhibit anticoagulant properties and inhibit platelet activation at low thrombin concentration in vitro. We hypothesized that the rapid occlusive thrombosis in HK-deficient (HKd) rats following endothelial injury of the aorta results from enhanced platelet aggregation by thrombin. The effects of D3 (G235-M357) or D3-derived peptides on thrombosis in vivo were tested. D3 and its exon 7C terminal peptide (E7CP, K270-Q292), expressed as glutathione S-transferase (GST) fusion proteins (GST-D3, GST-E7CP), or GST alone, as well as cleaved HK (HKa) or synthetic peptide E7CP, were infused intravenously 10 min before endothelial injury. Blood flow was reduced down to 10% of baseline flow within 28 +/- 5.2 min by a platelet-fibrin thrombus in GST-treated HKd rats compared with >240 min in GST-treated normal HK rats (wild type). GST-D3, GST-E7CP, HKa, or E7CP infusion prolonged the flow time to 233, >240, 223, and >240 min, respectively, in HKd rats. When GST-E7CP was infused 10 min after the injury, blood flow was maintained for >240 min. Thrombin-antithrombin concentrations were elevated by injury in HKd rats receiving GST from 35 to 55 microg/l and decreased with GST-E7CP, HKa, or E7CP reconstitution to 40, 15, and 9 microg/l, respectively. We conclude that HKd rats are prothrombotic and that HKa, kininogen D3, and its fragment E7CP modulate arterial thrombosis after endothelial injury. 相似文献
47.
48.
Plant Growth Regulators and Induction of Leaf Senescence in Nitrogen-Deprived Wheat Plants 总被引:1,自引:0,他引:1
M. Victoria Criado Irma N. Roberts Mariela Echeverria Atilio J. Barneix 《Journal of Plant Growth Regulation》2007,26(4):301-307
The sequence of events and the signals that regulate the remobilization of nitrogen (N) reserves during senescence induced
by N starvation were studied in leaf 3, the last fully expanded leaf, in 17-day-old wheat (Triticum aestivum L.) plants. The first event observed was a rapid decrease in the isopentenyl adenosine (iPA) concentration during the first
24 h of N starvation. No differences in t-zeatin riboside and dihydrozeatin riboside concentrations were observed until the
end of the assay. During the following 6 days, a decrease in soluble amino acids, chlorophyll, and protein, as well as an
increase in soluble sugar concentration and endoproteolytic activity, could be observed. At day 3 of the experiment, the abscisic
acid (ABA) concentration in the leaves of N-deprived plants started to increase. After 6 days of N deprivation there was a
rise in oxidative stress, as indicated by the increase in malondialdehyde concentration, as well as a decrease in the activities
of antioxidant enzymes catalase and ascorbate peroxidase. To analyze interactions with leaf development, the first, second,
third, and fourth leaves were studied. iPA concentration decreased in all the leaf stages, including leaf 4, which was not
fully expanded. A linear correlation between iPA and protein concentration was determined. These results suggest that the
sharp fall in iPA could be the earliest event that induces protein degradation during the development of senescence induced
by N deficiency, and that only later is ABA accumulated and oxidative stress developed. 相似文献
49.
Mammalian protein-protein interaction trap (MAPPIT) analysis of STAT5, CIS, and SOCS2 interactions with the growth hormone receptor 总被引:1,自引:0,他引:1
50.
Longitudinal data on telomere length in leukocytes from newborn baboons support a marked drop in stem cell turnover around 1 year of age 总被引:1,自引:0,他引:1
Stem cells of various tissues are typically defined as multipotent cells with 'self-renewal' properties. Despite the increasing interest in stem cells, surprisingly little is known about the number of times stem cells can or do divide over a lifetime. Based on telomere-length measurements of hematopoietic cells, we previously proposed that the self-renewal capacity of hematopoietic stem cells is limited by progressive telomere attrition and that such cells divide very rapidly during the first year of life. Recent studies of patients with aplastic anemia resulting from inherited mutations in telomerase genes support the notion that the replicative potential of hematopoietic stem cells is directly related to telomere length, which is indirectly related to telomerase levels. To revisit conclusions about stem cell turnover based on cross-sectional studies of telomere length, we performed a longitudinal study of telomere length in leukocytes from newborn baboons. All four individual animals studied showed a rapid decline in telomere length (approximately 2-3 kb) in granulocytes and lymphocytes in the first year after birth. After 50-70 weeks the telomere length appeared to stabilize in all cell types. These observations suggest that hematopoietic stem cells, after an initial phase of rapid expansion, switch at around 1 year of age to a different functional mode characterized by a markedly decreased turnover rate. 相似文献