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51.
Polygalacturonase (PG) activity and changes in respiratory intensity of apple fruits were investigated. The respiratory rate was decreased to a preclimacteric minimum from 30 Aug. to 20 Sept., Then increased to a climacteric peak (20–30 Sept.) and again drop down gradually with approaching the senescence stage. The PG activity was undetectable in a developing fruit until the onset climacteric phase. It rose rapidly after harvest, and reaching its highest level on 27 Oct. Just a month after the climacteric peak. The PG activity fell gradually. The amount of the fractions of pectic acid in fruits changed with the modifications of PG activity. With the ripening of fruits, the content of alcohol-soluble small molecules of pectic acids was increased from 12 to 13 5 mg/100 g of tissue, while the amount of alcohol- insoluble large molecules of pectic acids reduced from 530 to 280/100 g of tissue. PG activity would indicate the destruction of cell walls and the separation of cells. The onset of softening of fruits occurred 20 days after the rise of PG activity. It is supposed that the process of softening is directly controlled by PG activity. 相似文献
52.
53.
Rutheford Bill; Jenkins Jeanne; Zorich Nora; Galsky Alan 《Plant & cell physiology》1976,17(6):1111-1117
Adenyl cyclase activity was found in crown-gall tumor tissueobtained from the inoculation of the primary leaves of Pintobeans with Agrobacterium tumefaciens strain B6. Consistentlymore enzyme activity was found, however, in normal leaf tissueor wounded leaf tissue inoculated with sterile broth than inthe tumor tissue. On the other hand, cyclic-AMP phosphodiesteraseactivity increased with tumor age. These two enzymes were also found in extracts of both infectiousand non-infectious strains of Agrobacterium tumefaciens, althoughno obvious correlation between the production of these enzymesand infectivity could be established. Some of the implicationsof these results will be discussed. (Received May 25, 1976; ) 相似文献
54.
AG. van Ginkel BJ. Sorgdrager M. A. de Graaf I. Karalis N. Ajmone Marsan 《Netherlands heart journal》2014,22(2):77-79
We report a case of an allergic reaction after the administration of an echocardiographic contrast agent which resulted in ST-segment elevation. Hypersensitivity and allergic reactions are known causes of acute cardiovascular events. However, only limited reports are available which suggest the exact mechanism of the occurrence of angina or myocardial infarction during severe allergic reactions. In our case, through invasive imaging (coronary angiography and IVUS) we have shown for the first time a transient coronary spasm in the absence of intra-coronary thrombus and only minimal neointimal hyperplasia. 相似文献
55.
A nearly universal feature of intron sequences is that even closely related
species exhibit a large number of insertion/deletion differences. The goal
of the analysis described here is to test whether the observed pattern of
insertion/deletion events in the genealogy of the myosin alkali light chain
(Mlc1) gene is consistent with neutrality, and if not, to determine the
underlying forces of evolutionary change. Mlc1 pre-mRNA is alternatively
spliced, and one constraint is that signals necessary for
tissue-specificity of directed splicing must be conserved. If the total
length of an intron is functionally constrained, then the distribution of
indels on branches of the gene genealogy should reflect a departure from
randomness. Here we perform a phylogenetic analysis, inferring ancestral
states wherever possible on a phylogeny of 29 alleles of Mlc1 from six
species of Drosophila. Observed patterns of indels on the genealogy were
compared to those from simulated data, with the result that we cannot
reject the null hypothesis of neutrality. A clear departure from a neutral
prediction was seen in the excess folding free energy predicted for the
introns flanking the alternatively spliced exon. Relative rate tests also
suggest a retardation in the rate of Mlc1 sequence evolution in the
simulans clade.
相似文献
56.
Román González-Prieto Sabine AG Cuijpers Martijn S Luijsterburg Haico van Attikum Alfred CO Vertegaal 《EMBO reports》2015,16(4):512-519
SUMOylation plays important roles in the DNA damage response. However, whether it is important for interstrand crosslink repair remains unknown. We report that the SLX4 nuclease scaffold protein is regulated by SUMOylation. We have identified three SUMO interaction motifs (SIMs) in SLX4, mutating all of which abrogated the binding of SLX4 to SUMO-2 and covalent SLX4 SUMOylation. An SLX4 mutant lacking functional SIMs is not recruited to PML nuclear bodies nor stabilized at laser-induced DNA damage sites. Additionally, we elucidated a novel role for PARylation in the recruitment of SLX4 to sites of DNA damage. Combined, our results uncover how SLX4 is regulated by post-translational modifications. 相似文献
57.
Joel AG van Roon 《Arthritis research & therapy》2007,9(4):106
Fcγ receptors (FcγRs) bind the constant Fc region of IgG molecules. IgG/antigen-containing immune complexes elicit a variety
of effector functions in cells that express activating FcγRs. Because activating FcγRs are present on cells from the innate
immune system, such as dendritic cells, monocytes/macrophages and granulocytes, these IgG receptors form a crucial link between
the innate and the acquired immune systems. Recently, the ability to detect the inhibitory FcγRIIb on cells has indicated
an imbalance between activating and inhibitory FcγRs in rheumatoid arthritis. This progress offers an opportunity to study
modulation of FcγR balance and could stimulate development of FcγR-directed immunotherapy. 相似文献
58.
GA3 (1 mM) promotes the germination of dark grown seeds of Lactucasativa variety "Spartan Lake" above levels obtained when theseseeds are germinated in the light for 18 hr. Cyclic-AMP alsopromotes the germination of these seeds in the dark but to amuch smaller extent than that obtainable with 1 mM GA3 and equivalentto levels obtained with 1 µM GA3. Combinations of lowconcentrations of GA3 and cyclic-AMP significantly increasedgermination over levels obtained with either compound alone,promoting germination at times to near optimum levels. GA3 isrequired for less than half the incubation period to bring aboutmaximum germination. ABA was found to inhibit the GA3 and cyclic-AMP induced responseas well as the response obtained with combinations of the nucleotideand hormone. Theophylline and caffeine in combination with lowGA3 concentrations promoted germination over seeds treated withthe hormone alone. Of a variety of adenine containing compoundstested only ADP and ATP gave responses similar to those obtainedwith cyclic-AMP. Some of the implications of these results arediscussed. (Received January 16, 1973; ) 相似文献
59.
Incubation of embryoless barley (Hordeum vulgare) half-seeds for 24 hours with 0.1 m glutamate or aspartate resulted in the release of 17 to 48% as much α-amylase as did incubation with 260 mμm gibberellin. With incubation periods of 48 to 51 hours these amino acids were on the average about half as active as response-saturating concentrations of gibberellin, and in some experiments they were essentially as active. Citric acid cycle intermediates, glycolytic pathway intermediates, and cofactors of these pathways failed to induce α-amylase synthesis, while the following compounds were active: asparagine, homoserine, diaminopimelate, isoleucine, methionine, glutamine, ornithine, citrulline, argininosuccinate, and δ-aminolevulinate. However, threonine, lysine, β-alanine, alanine, γ-aminobutyrate, α-ketobutyrate, proline, arginine, glycine, leucine, and putrescine were inactive. Two patterns were noted in the list of active and inactive compounds: (a) all of the active compounds contain an amino group and are biosynthetically derived from citric acid cycle intermediates; and (b) biosynthetic precursors of the amino acids arginine, proline, threonine, and lysine were active whereas these amino acids were not. 相似文献
60.
Rabbits were injected with cell walls obtained from crown-gall tumor tissue or the corresponding cell walls from normal potato tissue. The serum obtained from rabbits 53 days after they were injected with tumor cell walls contained immunoglobins that reacted with both tumor and normal cell walls as well as with the cells from the inciting strain of Agrobacterium tumefaciens. When this serum was repeatedly absorbed against normal cell walls and the cells of the inciting strain of Agrobacterium tumefaciens, only tumor-specific immunoglobins remained. These immunoglobins did not react with cell walls obtained from meristematic (nontumorous) potato tissue. Yet this same serum reacted with crown-gall tumor cell walls obtained from turnip and carrot discs. 相似文献