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21.
We determined the interactive effects of irradiance, elevated CO2 concentration (EC), and temperature in carrot (Daucus carota var. sativus). Plants of the cv. Red Core Chantenay (RCC) were grown in a controlled environmental plant growth room and exposed to 3
levels of photosynthetically active radiation (PAR) (400, 800, 1 200 μmol m−2 s−1), 3 leaf chamber temperatures (15, 20, 30 °C), and 2 external CO2 concentrations (C
a), AC and EC (350 and 750 μmol mol−1, respectively). Rates of net photosynthesis (P
N) and transpiration (E) and stomatal conductance (g
s
) were measured, along with water use efficiency (WUE) and ratio of internal and external CO2 concentrations (C
i/C
a). P
N revealed an interactive effect between PAR and C
a. As PAR increased so did P
N under both C
a regimes. The g
s
showed no interactive effects between the three parameters but had singular effects of temperature and PAR. E was strongly influenced by the combination of PAR and temperature. WUE was interactively affected by all three parameters.
Maximum WUE occurred at 15 °C and 1 200 μmol m−2 s− 1 PAR under EC. The C
i
/C
a
was influenced independently by temperature and C
a. Hence photosynthetic responses are interactively affected by changes in irradiance, external CO2 concentration, and temperature. EC significantly compensates the inhibitory effects of high temperature and irradiance on
P
N and WUE. 相似文献
22.
Mason T. MacDonald Rajasekaran R. Lada Alex I. Martynenko Martine Dorais Steeve Pepin Yves Desjardins 《Trees - Structure and Function》2010,24(5):879-886
Post-harvest needle abscission is a major challenge for Christmas tree and greenery industries. It was hypothesized that ethylene
triggers abscission in balsam fir. Three experiments were conducted to test this hypothesis. In experiment 1, 70 balsam fir
branches were collected, placed in water, and ethylene evolution was observed over time. In experiment 2, a 2 × 5 factorial
experiment was designed to determine the effect of exogenous ethylene and an ethylene receptor blocker, 1-methylcyclopropene
(1-MCP), on needle abscission. In experiment 3, a 2 × 6 factorial experiment was designed to determine the effect of exogenous
ethylene and an ethylene inhibitor, aminoethoxyvinylglycine (AVG), on needle abscission. It was found that ethylene evolution
was the highest 1–2 days prior to needle abscission, which was consistent in untreated branches and branches exposed to exogenous
ethylene. Exposure to exogenous ethylene significantly decreased needle retention by 63%. When ethylene receptors were blocked
by 1-MCP, needle retention increased by 147% despite the presence of ethylene and increased by 73% in the absence of ethylene
when compared to the respective controls. When endogenous ethylene synthesis was inhibited by AVG, there was no improvement
in needle retention in the presence of ethylene, but there was a 113% increase in needle retention in the absence of exogenous
ethylene. Ethylene is strongly implicated as the signal triggering abscission in root-detached balsam fir. 相似文献
23.
Phytoextraction of Risk Elements by Willow and Poplar Trees 总被引:1,自引:0,他引:1
To characterize the phytoextraction efficiency of two clones of willow trees (Salix x smithiana Willd., Salix rubens) and two clones of poplar trees (Populus nigra x maximowiczii, Populus nigra Wolterson) were planted in contaminated soil (0.4–2.0 mg Cd.kg?1, 78–313 mg Zn.kg?1, 21.3–118 mg Cu.kg?1). Field experiment was carried out in Czech Republic. The study investigated their ability to accumulate heavy metals (Cd, Zn, and Cu) in harvestable plant parts. The poplars produced higher amount of biomass than willows. Both Salix clones accumulated higher amount of Cd, Zn and Cu in their biomass (maximum 6.8 mg Cd.kg?1, 909 mg Zn.kg?1, and 17.7 mg Cu.kg?1) compared to Populus clones (maximum 2.06 mg Cd.kg?1, 463 mg Zn.kg?1, and 11.8 mg Cu.kg?1). There were no significant differences between clones of individual species. BCs for Cd and Zn were greater than 1 (the highest in willow leaves). BCs values of Cu were very low. These results indicate that Salix is more suitable plant for phytoextraction of Cd and Zn than Populus. The Cu phytoextraction potential of Salix and Populus trees was not confirmed in this experiment due to low soil availability of this element. 相似文献
24.
Daniel G Volc J Filonova L Plíhal O Kubátová E Halada P 《Applied and environmental microbiology》2007,73(19):6241-6253
A novel alcohol oxidase (AOX) has been purified from mycelial pellets of the wood-degrading basidiomycete Gloeophyllum trabeum and characterized as a homooctameric nonglycosylated protein with native and subunit molecular masses of 628 and 72.4 kDa, containing noncovalently bonded flavin adenine dinucleotide. The isolated AOX cDNA contained an open reading frame of 1,953 bp translating into a polypeptide of 651 amino acids displaying 51 to 53% identity with other published fungal AOX amino acid sequences. The enzyme catalyzed the oxidation of short-chain primary aliphatic alcohols with a preference for methanol (K(m) = 2.3 mM, k(cat) = 15.6 s(-1)). Using polyclonal antibodies and immunofluorescence staining, AOX was localized on liquid culture hyphae and extracellular slime in sections from degraded wood and on cotton fibers. Transmission electron microscopy immunogold labeling localized the enzyme in the hyphal periplasmic space and wall and on extracellular tripartite membranes and slime, while there was no labeling of hyphal peroxisomes. AOX was further shown to be associated with membranous or slime structures secreted by hyphae in wood fiber lumina and within the secondary cell walls of degraded wood fibers. The differences in AOX targeting compared to the known yeast peroxisomal localization were traced to a unique C-terminal sequence of the G. trabeum oxidase, which is apparently responsible for the protein's different translocation. The extracellular distribution and the enzyme's abundance and preference for methanol, potentially available from the demethylation of lignin, all point to a possible role for AOX as a major source of H(2)O(2), a component of Fenton's reagent implicated in the generally accepted mechanisms for brown rot through the production of highly destructive hydroxyl radicals. 相似文献
25.
M.E. Lobashev has brilliantly postulated in 1947 that error-prone repair contribute to mutations in cells. This was shown to be true once the mechanisms of UV mutagenesis in Escherichia coli were deciphered. Induced mutations are generated during error-prone SOS DNA repair with the involvement of inaccurate DNA polymerases belonging to the Y family. Currently, several distinct mutator enzymes participating in spontaneous and induced mutagenesis have been identified. Upon induction of these proteins, mutation rates increase by several orders of magnitude. These proteins regulate the mutation rates in evolution and in ontogeny during immune response. In jawed vertebrates, somatic hypermutagenesis occurs in the variable regions of immunoglobulin genes, leading to affinity maturation of antibodies. The process is initiated by cytidine deamination in DNA to uracil by AID (Activation-Induced Deaminase). Further repair of uracil-containing DNA through proteins that include the Y family DNA polymerases causes mutations, induce gene conversion, and class switch recombination. In jawless vertebrates, the variable lymphocyte receptors (VLR) serve as the primary molecules for adaptive immunity. Generation of mature VLRs most likely depends on agnathan AID-like deaminases. AID and its orthologs in lamprey (PmCDA1 and PMCDA2) belong to the AID/APOBEC family of RNA/DNA editing cytidine deaminases. This family includes enzymes with different functions: APOBEC1 edits RNA, APOBEC3 restricts retroviruses. The functions of APOBEC2 and APOBEC4 have not been yet determined. Here, we report a new member of the AID/APOBEC family, APOBEC5, in the bacterium Xanthomonas oryzae. The widespread presence of RNA/DNA editing deaminases suggests that they are an ancient means of generating genetic diversity. 相似文献
26.
Lada V. Stepanova Gennady L. Burygin Valentina E. Nikitina Olga M. Tsivileva 《World journal of microbiology & biotechnology》2011,27(7):1579-1585
Both quantitative and qualitative estimations of the basidiomycete Grifola frondosa lectin binding to the specific and non-specific polyclonal rabbit antibodies were attempted. The lectin complexation with
homological antibodies was shown to be characterized by greater binding constants as compared to non-homological antibodies.
Therewith the values of changes in standard free energy ∆G
0 displaying a strength of both complexes were essentially the same. The data obtained testify to universality of biospecific
reactions “antigen–antibody” and “lectin–carbohydrate” at a molecular level, and could give new insight into the phenomenon
of these biospecific interactions. The actual specificity in the above bio-recognition processes could differ from the results
of in vitro assays using lectins, and, therefore, should be interpreted carefully when concluding on the lectins behaviour
in living systems. 相似文献
27.
The siliceous marine sponge Suberites domuncula is a member of the most ancient and simplest extant phylum of multicellular animals-Porifera, which have branched off first from the common ancestor of all Metazoa. We have determined primary structures of 79 ribosomal proteins (r-proteins) from S. domuncula: 32 proteins from the small ribosomal subunit and 47 proteins from the large ribosomal subunit. Only L39 and L41 polypeptides (51 and 25 residues long in rat, respectively) are missing. The sponge S. domuncula is, after nematode Caenorhabditis elegans and insect Drosophila melanogaster the third representative of invertebrates with known amino acid sequences of all r-proteins. The comparison of S. domuncula r-proteins with r-proteins from D. melanogaster, C. elegans, rat, Arabidopsis thaliana and Saccharomyces cerevisiae revealed very interesting findings. The majority of the sponge r-proteins are more similar to their homologues from rat, than to those either from invertebrates C. elegans and D. melanogaster, or yeast and plant. With few exceptions, the overall sequence conservation between sponge and rat r-proteins is 80% or higher. The phylogenetic tree of concatenated r-proteins from 6 eukaryotic species (rooted with archaeal r-proteins) has the shortest branches connecting sponge and rat. Both model invertebrate organisms experienced recently accelerated evolution and therefore sponge r-proteins very probably better reflect structures of proteins in the ancestral metazoan ribosome, which changed only little during metazoan evolution. Furthermore, r-proteins from the plant A. thaliana are significantly closer to metazoan r-proteins than are those from the yeast S. cerevisiae. 相似文献
28.
Mrácek J Greiner S Cho WK Rauwolf U Braun M Umate P Altstätter J Stoppel R Mlcochová L Silber MV Volz SM White S Selmeier R Rudd S Herrmann RG Meurer J 《Genomics》2006,88(3):372-380
Coevolution of cellular genetic compartments is a fundamental aspect in eukaryotic genome evolution that becomes apparent in serious developmental disturbances after interspecific organelle exchanges. The genus Oenothera represents a unique, at present the only available, resource to study the role of the compartmentalized plant genome in diversification of populations and speciation processes. An integrated approach involving cDNA cloning, EST sequencing, and bioinformatic data mining was chosen using Oenothera elata with the genetic constitution nuclear genome AA with plastome type I. The Gene Ontology system grouped 1621 unique gene products into 17 different functional categories. Application of arrays generated from a selected fraction of ESTs revealed significantly differing expression profiles among closely related Oenothera species possessing the potential to generate fertile and incompatible plastid/nuclear hybrids (hybrid bleaching). Furthermore, the EST library provides a valuable source of PCR-based polymorphic molecular markers that are instrumental for genotyping and molecular mapping approaches. 相似文献
29.
Fullerton GD Nes E Amurao M Rahal A Krasnosselskaia L Cameron I 《Cell biology international》2006,30(1):66-73
A molecular model is proposed to explain water 1H NMR spin-lattice relaxation at different levels of hydration (NMR titration method) on collagen. A fast proton exchange model is used to identify and characterize protein hydration compartments at three distinct Gibbs free energy levels. The NMR titration method reveals a spectrum of water motions with three well-separated peaks in addition to bulk water that can be uniquely characterized by sequential dehydration. Categorical changes in water motion occur at critical hydration levels h (g water/g collagen) defined by integral multiples N = 1, 4 and 24 times the fundamental hydration value of one water bridge per every three amino acid residues as originally proposed by Ramachandran in 1968. Changes occur at (1) the Ramachandran single water bridge between a positive amide and negative carbonyl group at h1 = 0.0658 g/g, (2) the Berendsen single water chain per cleft at h2 = 0.264 g/g, and (3) full monolayer coverage with six water chains per cleft level at h3 = 1.584 g/g. The NMR titration method is verified by comparison of measured NMR relaxation compartments with molecular hydration compartments predicted from models of collagen structure. NMR titration studies of globular proteins using the hydration model may provide unique insight into the critical contributions of hydration to protein folding. 相似文献
30.
Hubacek JA Bohuslavova R Kuthanova L Kubinova R Peasey A Pikhart H Marmot MG Bobak M 《Obesity (Silver Spring, Md.)》2008,16(12):2764-2766
Variants in the FTO (oxoglutarate-dependent nucleic acid demethylase) gene have been associated with the BMI determination in Western European and North American populations. To widen the geographical coverage of the FTO studies, we have analyzed the association between the FTO gene variant rs17817449 (G>C) and obesity in a Slavic Eastern European population. A total of 3,079 males and 3,602 females 45-69 years old were randomly selected from population registers of seven Czech cities. We examined three indices of obesity: BMI (kg/m(2)), waist circumference, and waist-to-hip ratio (WHR). The FTO rs17817449 variant was significantly associated with BMI both in males (GG 28.7 +/- 4.1; GT 28.3 +/- 3.9; TT 28.0 +/- 3.9; P = 0.003) and females (GG 28.7 +/- 5.2; GT 28.2 +/- 5.1; TT 27.2 +/- 4.9; P < 0.001); the associations were not affected by adjustment for age, smoking, socioeconomic status, and physical activity. The FTO variant was also associated with waist circumference (difference between GG and TT was 1.1 cm (P = 0.043) in men and 2.4 cm (P < 0.001) in women) but this relationship disappeared after adjustment for BMI. Similarly, BMI explained the weak association of FTO with WHR and C-reactive protein. FTO was not associated with plasma total and high-density lipoprotein cholesterol, triglycerides, blood glucose, and blood pressure. These results confirm that in a Slavic population the FTO variant is strongly associated with BMI but not with other risk factors. 相似文献