Breakdown of self-incompatibility in a natural population of Petunia axillaris caused by loss of pollen function

Although Petunia axillaris subsp. axillaris is described as a self-incompatible taxon, some of the natural populations we have identified in Uruguay are composed of both self-incompatible and self-compatible plants. Here, we studied the self-incompatibility (SI) behavior of 50 plants derived from such a mixed population, designated U83, and examined the cause of the breakdown of SI. Thirteen plants were found to be self-incompatible, and the other 37 were found to be self-compatible. A total of 14 S-haplotypes were represented in these 50 plants, including two that we had previously identified from another mixed population, designated U1. All the 37 self-compatible plants carried either an S(C1)- or an S(C2)-haplotype. S(C1)S(C1) and S(C2)S(C2) homozygotes were generated by self-pollination of two of the self-compatible plants, and they were reciprocally crossed with 40 self-incompatible S-homozygotes (S(1)S(1) through S(40)S(40)) generated from plants identified from three mixed populations, including U83. The S(C1)S(C1) homozygote was reciprocally compatible with all the genotypes examined. The S(C2)S(C2) homozygote accepted pollen from all but the S(17)S(17) homozygote (identified from the U1 population), but the S(17)S(17) homozygote accepted pollen from the S(C2)S(C2) homozygote. cDNAs encoding S(C2)- and S(17)-RNases were cloned and sequenced, and their nucleotide sequences were completely identical. Analysis of bud-selfed progeny of heterozygotes carrying S(C1) or S(C2) showed that the SI behavior of S(C1) and S(C2) was identical to that of S(C1) and S(C2) homozygotes, respectively. All these results taken together suggested that the S(C2)-haplotype was a mutant form of the S(17)-haplotype, with the defect lying in the pollen function. The possible nature of the mutation is discussed.     

Elevated amniotic fluid F₂-isoprostane: a potential predictive marker for preeclampsia

In the complex mechanism of preeclampsia, oxidative stress is an important pathogenic factor, and F₂-isoprostane is a marker of oxidative stress and lipid peroxidation. The objective of this study was to identify if the amniotic fluid (AF) levels of F₂-isoprostanes were elevated in women who later developed preeclampsia. In this study, we analyzed AF F₂-isoprostane concentrations with enzyme immunoassay (EIA), and the EIA results could be validated by quantitative mass spectrometry. The mean AF concentration of F₂-isoprostanes was significantly higher in pregnancies with subsequent development of preeclampsia (123.1 ± 57.6 pg/ml, n = 85) than in controls (73.8 ± 36.6 pg/ml, n = 85). The AF elevation of F₂-isoprostanes was even higher in the preeclampsia with intrauterine growth restriction group (138.3 ± 65.2 pg/ml, n = 39). The area under the curve of the receiver operating characteristics analysis for AF F₂-isoprostanes assay was 0.81, supporting its potential as a biomarker for preeclampsia. These results indicate that oxidative stress existed before the onset of clinical preeclampsia, further suggesting that the elevation of AF F₂-isoprostanes may be used as a guide for antioxidant supplementation to reduce the risk and/or severity of preeclampsia.     

The GLI-Kruppel family of human genes.

Previous characterization of GLI, a gene found to be amplified and expressed in a subset of human brain tumors, revealed the presence of five tandem zinc fingers related to those of Krüppel (Kr), a Drosophila segmentation gene of the gap class. We have used the GLI cDNA as a molecular probe to isolate related sequences from the human genome. Partial characterization of six related loci, including sequence determination, expression studies, and chromosome localization, revealed that each locus could encode a separate finger protein. The predicted proteins all had similar H-C links, i.e., a conserved stretch of 9 amino acids connecting the C-terminal histidine of one finger to the N-terminal cysteine of the next. On the basis of amino acid sequence and intron-exon organization, the genes could be placed into one of two subgroups: the GLI subgroup (with the consensus finger amino acid sequence [Y/F]XCX3GCX3[F/Y]X5LX2HX3-4H[T/S]GEKP) or the Kr subgroup (with the consensus finger amino acid sequence [Y/F]XCX2CX3FX5LX2HXRXHTGEKP). Unlike GLI or Kr, most of the newly isolated genes were expressed in many adult tissues. The predicted proteins probably control the expression of other genes and, by analogy with Kr and GLI, may be important in human development, tissue-specific differentiation, or neoplasia.     

Phenotypic plasticity and genetic variation in leaf traits of Yushania niitakayamensis (Bambusoideae; Poaceae) in contrasting light environments

Journal of Plant Research - Yushania niitakayamensis (Bambusoideae; Poaceae), a perennial grass distributed from mid to high elevations in Taiwan, is often found growing in exposed grassland or...     

A novel naphthalimide derivative reduces platelet activation and thrombus formation via suppressing GPVI

Naphthalimide derivatives have multiple biological activities, including antitumour and anti-inflammatory activities. We previously synthesized several naphthalimide derivatives; of them, compound 5 was found to exert the strongest inhibitory effect on human DNA topoisomerase II activity. However, the effects of naphthalimide derivatives on platelet activation have not yet been investigated. Therefore, the mechanism underlying the antiplatelet activity of compound 5 was determined in this study. The data revealed that compound 5 (5–10 μM) inhibited collagen- and convulxin- but not thrombin- or U46619-mediated platelet aggregation, suggesting that compound 5 is more sensitive to the inhibition of glycoprotein VI (GPVI) signalling. Indeed, compound 5 could inhibit the phosphorylation of signalling molecules downstream of GPVI, followed by the inhibition of calcium mobilization, granule release and GPIIb/IIIa activation. Moreover, compound 5 prevented pulmonary embolism and prolonged the occlusion time, but tended to prolong the bleeding time, indicating that it can prevent thrombus formation but may increase bleeding risk. This study is the first to demonstrate that the naphthalimide derivative compound 5 exerts antiplatelet and antithrombotic effects. Future studies should modify compound 5 to synthesize more potent and efficient antiplatelet agents while minimizing bleeding risk, which may offer a therapeutic potential for cardiovascular diseases.     

Genomic expression pattern in Saccharomyces cerevisiae cells in response to high hydrostatic pressure

Gene expression patterns in response to hydrostatic pressure were determined by whole genome microarray hybridization. Functional classification of the 274 genes affected by pressure treatment of 200 MPa for 30 min revealed a stress response expression profile. The majority of the >2-fold upregulated genes were involved in stress defense and carbohydrate metabolism while most of the repressed ones were in cell cycle progression and protein synthesis categories. Furthermore, uncharacterized genes were among the 10 highest expressed sequences and represented 45% of the total upregulated genes. The results of this study revealed a hydrostatic pressure-specific stress response pattern and suggested interesting information about the mechanisms involved in adaptation of cells to a high-pressure environment.     

Efficiently mining gene expression data via a novel parameterless clustering method

Clustering analysis has been an important research topic in the machine learning field due to the wide applications. In recent years, it has even become a valuable and useful tool for in-silico analysis of microarray or gene expression data. Although a number of clustering methods have been proposed, they are confronted with difficulties in meeting the requirements of automation, high quality, and high efficiency at the same time. In this paper, we propose a novel, parameterless and efficient clustering algorithm, namely, correlation search technique (CST), which fits for analysis of gene expression data. The unique feature of CST is it incorporates the validation techniques into the clustering process so that high quality clustering results can be produced on the fly. Through experimental evaluation, CST is shown to outperform other clustering methods greatly in terms of clustering quality, efficiency, and automation on both of synthetic and real data sets.     

Evolutionally guided enzyme design

A combination of "rational" and "irrational" strategies for the creation of enzymes with novel properties is proving to be a powerful concept in the field of enzyme engineering. Guided by principles of physical organic chemistry, rational design strategies are used to identify suitable target enzymes and to choose appropriate molecular biological methods for engineering purposes. In contrast, irrational (or random) strategies are centered around the biological paradigm of stochastic molecular evolution. As illustrated in this review, such a hybrid approach is particularly useful for the design of new modular enzymes. (c) 1996 John Wiley & Sons, Inc.     

Kinetic behaviour and allosteric regulation of human deoxycytidylate deaminase derived from leukemic cells

Deoxycytidylate deaminase has been highly purified (1232-fold) from human leukemia CCRF-CEM cells. The native molecular weight of the enzyme is 108 000 and subunit molecular weight 50 500, suggesting that the native enzyme exists as a dimer. The enzyme exhibits a sigmoidal initial velocity vs substrate concentration curve and is regulated by allosteric effectors, dCTP and TTP. The curve relating substrate concentration to initial velocity was changed from a sigmoidal shape to a hyperbolic one by the activator dCTP, while the inhibitor TTP increased the sigmoidicity of the curve. The molecular weight of deoxycytidylate deaminase was unchanged in the presence of allosteric effectors, indicating that aggregation-disaggregation is not the basis of regulation. Deoxycytidylate deaminase exhibited the greatest affinity for the substrate dCMP, with lesser affinity for ara-CMP, and least affinity for CMP. Ara-CMP was an effective substrate in the presence of dCTP concentrations exceeding 4 microM. These data indicate that human neoplastic cell deoxycytidylate deaminase is a highly regulated allosteric enzyme, which is likely to have a significant influence on cellular dUMP, dCTP and TTP pools. These findings further suggest, that the enzyme through its influence on dUMP levels is likely to modulate the biochemical effects of pyrimidine antimetabolites active against the thymidylate synthetase reaction and in the presence of elevated dCTP pools will promote deamination of ara-CMP to the inactive ara-UMP.