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991.
Lunde C Zygadlo A Simonsen HT Nielsen PL Blennow A Haldrup A 《Physiologia plantarum》2008,134(3):508-521
Sulfur-deficient plants generate a lower yield and have a reduced nutritional value. The process of sulfur acquisition and assimilation play an integral role in plant metabolism, and response to sulfur deficiency involves a large number of plant constituents. Rice (Oryza sativa) is the second most consumed cereal grain, and the effects of sulfur deprivation in rice were analyzed by measuring changes in photosynthesis, carbohydrate metabolism, and antioxidants. The photosynthetic apparatus was severely affected under sulfur deficiency. The Chl content was reduced by 49% because of a general reduction of PSII and PSI and the associated light-harvesting antenna. The PSII efficiency was 31% lower at growth light, and the ability of PSI to photoreduce NADP+ was decreased by 61%. The Rubisco content was also significantly reduced in the sulfur-deprived plants. The imbalances between PSII and PSI, and between photosynthesis and carbon fixation led to a general over-reduction of the photosynthetic electron carriers (higher 1-q(P)). Chromatographic analysis showed that the level of monosaccharides was lower and starch content higher in the sulfur-deprived plants. In contrast, no changes in metabolite levels were found in the tricarboxylic acid or Calvin cycle. The level of the thiol-containing antioxidant, GSH, was 70% lower and the redox state was significantly more oxidized. These changes in GSH status led to an upregulation of the cytosolic isoforms of GSH reductase and monodehydroascorbate reductase. In addition, alternative antioxidants like flavonoids and anthocyanins were increased in the sulfur-deprived plants. 相似文献
992.
Sucrose transporter StSUT4 from potato affects flowering, tuberization, and shade avoidance response 总被引:9,自引:1,他引:8
Chincinska IA Liesche J Krügel U Michalska J Geigenberger P Grimm B Kühn C 《Plant physiology》2008,146(2):515-528
Sucrose (Suc) transporters belong to a large gene family. The physiological role of SUT1 proteins has been intensively investigated in higher plants, whereas that of SUT4 proteins is so far unknown. All three known Suc transporters from potato (Solanum tuberosum), SUT1, SUT2, and SUT4, are colocalized and their RNA levels not only follow a diurnal rhythm, but also oscillate in constant light. Here, we examined the physiological effects of transgenic potato plants on RNA interference (RNAi)-inactivated StSUT4 expression. The phenotype of StSUT4-RNAi plants includes early flowering, higher tuber production, and reduced sensitivity toward light enriched in far-red wavelength (i.e. in canopy shade). Inhibition of StSUT4 led to tuber production of the strict photoperiodic potato subsp. andigena even under noninductive long-day conditions. Accumulation of soluble sugars and Suc efflux from leaves of transgenic plants are modified in StSUT4-RNAi plants, leading to modified Suc levels in sink organs. StSUT4 expression of wild-type plants is induced by gibberellins and ethephon, and external supply of gibberellic acid leads to even more pronounced differences between wild-type and StSUT4-RNAi plants regarding tuber yield and internode elongation, indicating a reciprocal regulation of StSUT4 and gibberellins. 相似文献
993.
Spatial heterogeneity is a significant aspect of ecosystem structure andfunction. Because ecological variables often are spatially autocorrelated,standard statistics frequently are not appropriate to analyze ecological data.In this paper, we use Mantel and partial Mantel tests to explore the spatialstructure of and relationships between several variables –micro-topography, substrate salinity, wrack cover and the density ofAster laurentianus – at two sites at the peripheryofa shallow lagoon at Îles de la Madeleine, Québec.A. laurentianus is an annual halophyte endemic tothe Gulf of St. Lawrence. It typically occurs in a narrow band (from ca. 50 to200 cm wide) at the periphery of shallow lagoons. In this habitat,plants are exposed to frequent deposition of plant debris (wrack) and to thelimiting effects of substrate salinity.Our analyses show that substrate salinity, wrack cover and density ofA. laurentianus are significantly correlated withtopography, and that wrack cover affects substrate salinity at both sites. Atthe first site, the abundance of A. laurentianus increasesprogressively with distance from the waterline, while at the second site,density increases initially, but then diminishes with distance from thewaterline. At the first site, the most important structuring variable is wrackdeposition, the effect of salinity on plant density being indirect. At thesecond site, which is somewhat sheltered, wrack deposition is far lessimportantand substrate salinity predominates over wrack deposition as structuringvariable. We suggest that A. laurentianus distributionalong the shores of shallow lagoons is limited both by substrate salinity andwrack deposition, but that the relative importance of these structuringvariables changes with the physical characteristics of the site. 相似文献
994.
995.
Begging behaviour as a key element in the parent–offspring conflict has been studied in many avian species. These types of
studies have nearly exclusively been based on call counts, and it is still not entirely clear whether begging calls themselves
contain any information. We studied begging behaviour in Wilson’s storm-petrel Oceanites oceanicus, a small procellariiform seabird. This species provides the opportunity to study the signalling value of begging calls in
the absence of potentially confounding factors such as nestling competition, previous feeding experiences and predation pressure.
We applied a new method using a semi-automatic spectrogram analysis software that measures the acoustic parameters of begging
calls. Our analysis revealed that the frequency parameters of begging calls reflect chicks’ current body condition, with chicks
in poorer condition uttering calls at higher frequencies. Chicks uttering higher pitched calls also received larger meals.
Our study shows that certain acoustic parameters of begging calls can indicate the state of a chick in Wilson’s storm-petrels. 相似文献
996.
Christina E. Lorén John W. Schrader Ulf Ahlgren Lena Gunhaga 《Differentiation; research in biological diversity》2009
The lens of the eye is derived from the non-neural ectoderm situated next to the optic vesicle. Fibroblast growth factor (FGF) signals play a major role at various stages of vertebrate lens development ranging from induction and proliferation to differentiation. Less is however known about the identity of genes that are induced by FGF activity within the lens. We have isolated and characterized mouse cytoplasmic activation/proliferation-associated protein-2 (Caprin2), with domains belonging to both the Caprin family and the C1q and tumour necrosis factor (TNF) super-family. Here we show that Caprin2 is expressed in the developing vertebrate lens in mouse and chick, and that Caprin2 expression is up-regulated in primary lens fiber cells, after the induction of crystallins the earliest known markers for differentiated lens fiber cells. Caprin2 is subsequently down-regulated in the centre of the lens at the time and at the position of the first fiber cell denucleation and terminal differentiation. In vitro analyses of lens fiber cell differentiation provide evidence that FGF activity emanating from neighboring prospective retinal cells is required and that FGF8 activity is sufficient to induce Caprin2 in lens fiber cells. These results not only provide evidence that FGF signals induce the newly characterized protein Caprin2 in the lens, but also support the general idea that FGF signals are required for lens fiber cell differentiation. 相似文献
997.
Probing the relationship between Gram-negative and Gram-positive S1 proteins by sequence analysis
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Philippe Salah Marco Bisaglia Pascale Aliprandi Marc Uzan Christina Sizun Fran?ois Bontems 《Nucleic acids research》2009,37(16):5578-5588
Escherichia coli ribosomal protein S1 is required for the translation initiation of messenger RNAs, in particular when their Shine–Dalgarno sequence is degenerated. Closely related forms of the protein, composed of the same number of domains (six), are found in all Gram-negative bacteria. More distant proteins, generally formed of fewer domains, have been identified, by sequence similarities, in Gram-positive bacteria and are also termed ‘S1 proteins’. However in the absence of functional information, it is generally difficult to ascertain their relationship with Gram-negative S1. In this article, we report the solution structure of the fourth and sixth domains of the E. coli protein S1 and show that it is possible to characterize their β-barrel by a consensus sequence that allows a precise identification of all domains in Gram-negative and Gram-positive S1 proteins. In addition, we show that it is possible to discriminate between five domain types corresponding to the domains 1, 2, 3, 4–5 and 6 of E. coli S1 on the basis of their sequence. This enabled us to identify the nature of the domains present in Gram-positive proteins and, subsequently, to probe the filiations between all forms of S1. 相似文献
998.
Kate V. Everett Barry A. Chioza Christina Georgoula Ashley Reece R. Mark Gardiner Eddie M. K. Chung 《Human genetics》2009,126(6):819-831
Infantile hypertrophic pyloric stenosis (IHPS) is the most common inherited form of gastrointestinal obstruction in infancy
with a striking male preponderance. Infants present with vomiting due to gastric outlet obstruction caused by hypertrophy
of the smooth muscle of the pylorus. Two loci specific to extended pedigrees displaying autosomal dominant inheritance have
been identified. A genome scan identified loci on chromosomes 11q14–q22 and Xq23–q24 which are predicted to be responsible
for a subset of smaller families with IHPS demonstrating non-Mendelian inheritance. The two linked chromosomal regions both
harbour functional candidate genes which are members of the canonical transient receptor potential (TRPC) family of ion channels.
Both TRPC5 (Xq23–q24) and TRPC6 (11q14–q22) have a potential role in smooth muscle control and hypertrophy. Here, we report suggestive evidence for a third
locus on chromosome 3q12–q25 (Z
max = 2.7, p < 0.004), a region which harbours a third TRPC gene, TRPC1. Fine mapping of all three genes using a tagSNP approach and re-sequencing identified a SNP in the promoter region of TRPC6 and a missense variant in exon 4 of TRPC6 which may be putative causal variants. 相似文献
999.
Mozaffari F Lindemalm C Choudhury A Granstam-Björneklett H Lekander M Nilsson B Ojutkangas ML Osterborg A Bergkvist L Mellstedt H 《Cancer immunology, immunotherapy : CII》2009,58(1):111-120
Immunotherapy is being increasingly utilized for adjuvant treatment for breast cancer (BC). We have previously described immune
functions during primary therapy for BC. The present study describes immune recovery patterns during long-term, unmaintained
follow-up after completion of adjuvant therapy.A group of patients with primary BC had been treated with adjuvant radio-chemotherapy
(RT + CT) 5-fluorouracil, epirubicin and cyclophosphamide (FEC) (n = 21) and another group with radiotherapy (RT) (n = 20) alone. Immunological testing of NK and T-cell functions was performed initially at the end of adjuvant treatment and
repeated after 2, 6 and 12 months. NK cell cytotoxicity was significantly higher (P < 0.05) at all time-points in patients than in age-matched controls and did not differ between the two treatments groups
during one year observation. In contrast, lower numbers of CD4 T-cells and lower expression of CD28 on T-cells was observed
particularly in RT + CT patients and did not normalize during the observation period. The numbers of Treg cells (CD4+CD25high) were low in the RT + CT group during follow-up, as well as expression of TCRξ, Zap70, p56lck, P59fyn and PI3 k in CD4+ cells. In contrast, expression of intracellular cytokines (IFN-γ, IL-2, IL-4) in CD4 and CD8 T cells were significantly higher
in RT + CT patients than in the RT group and the difference increased during follow-up. In conclusion, NK-cell cytotoxicity
increased during unmaintained long-term follow-up whereas CD4 and regulatory T cells as well as signal transduction molecules
remained low following adjuvant radio-chemotherapy. 相似文献
1000.
We modeled the expected range of seasonal and annual N2O flux from temperate, grain agroecosystems using Monte Carlo sampling of N2O flux field observations. This analysis is complimentary to mechanistic biogeochemical model outcomes and provides an alternative method of estimating N2O flux. Our analysis produced a range of annual N2O gas flux estimates with mean values overlapping with results from an intermodel comparison of mechanistic models. Mean seasonal N2O flux was 1–4% of available N, while median seasonal N2O flux was less than 2% of available N across corn, soybean, wheat, ryegrass, legume, and bare fallow systems. The 25th–75th percentile values for simulated average annualized N2O flux rates ranged from 1 to 12.2 kg N ha?1 in the conventional system, from 1.3 to 8.8 kg N ha?1 in the cover crop rotation, and from 0.8 to 9.3 kg N ha?1 in the legume rotation. Although these modeling techniques lack the seasonal resolution of mechanistic models, model outcomes are based on measured field observations. Given the large variation in seasonal N gas flux predictions resulting from the application of mechanistic simulation models, this data-derived approach is a complimentary benchmark for assessing the impact of agricultural policy on greenhouse gas emissions. 相似文献