In mammals, cadmium is widely considered as a non-genotoxic carcinogen acting through a methylation-dependent epigenetic mechanism. Here, the effects of Cd treatment on the DNA methylation patten are examined together with its effect on chromatin reconfiguration in Posidonia oceanica. DNA methylation level and pattern were analysed in actively growing organs, under short- (6 h) and long- (2 d or 4 d) term and low (10 mM) and high (50 mM) doses of Cd, through a Methylation-Sensitive Amplification Polymorphism technique and an immunocytological approach, respectively. The expression of one member of the CHROMOMETHYLASE (CMT) family, a DNA methyltransferase, was also assessed by qRT-PCR. Nuclear chromatin ultrastructure was investigated by transmission electron microscopy. Cd treatment induced a DNA hypermethylation, as well as an up-regulation of CMT, indicating that de novo methylation did indeed occur. Moreover, a high dose of Cd led to a progressive heterochromatinization of interphase nuclei and apoptotic figures were also observed after long-term treatment. The data demonstrate that Cd perturbs the DNA methylation status through the involvement of a specific methyltransferase. Such changes are linked to nuclear chromatin reconfiguration likely to establish a new balance of expressed/repressed chromatin. Overall, the data show an epigenetic basis to the mechanism underlying Cd toxicity in plants.

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In Posidonia oceanica cadmium induces changes in DNA methylation and chromatin patterning

https://bura.brunel.ac.uk/bitstream/2438/14401/3/FullText.pdf

Heat pipe based systems - Advances and applications

In vitro chromosome doubling can be induced by several antimitotic agents. The most commonly used are colchicine, oryzalin and trifluralin. The process of induced chromosome doubling in vitro consists of a typical succession of sub-processes, including an induction phase and a confirmation protocol to measure the rate of success. The induction step depends on a large number of variables: media, antimitotic agents, explant types, exposure times and concentrations. Flow cytometry is the pre-eminent method for evaluation of the induced polyploidization. However, alternative confirmation methods, such as chromosome counts and morphological observations, are also used. Since polyploidization has many consequences for plant growth and development, chromosome doubling has been intensively studied over the years and has found its way to several applications in plant breeding. This review gives an overview of the common methods of chromosome doubling in vitro, the history of the technique, and progress made over the years. The applications of chromosome doubling in a broader context are also discussed.

Mitotic chromosome doubling of plant tissues in vitro

Review of computational studies on boiling and condensation

CFD modeling of flow and heat transfer in a thermosyphon

Modeling the evaporation of a hydrocarbon feedstock in the convection section of a steam cracker

https://biblio.ugent.be/publication/414607/file/447354.pdf

CFD modeling of all gas–liquid and vapor–liquid flow regimes predicted by the Baker chart

Bud sporting, the consequence of sudden variations in gene expression of somatic cells, leads to the occurrence of phenotypically altered shoots in many vegetatively propagated plant species. In ornamentals, such as azalea (Rhododendron simsii), flower colour bud sports are appreciated as a valuable additional source of variation, and it is evident that both genetic and epigenetic mechanisms are involved in the creation of the whole colour range. Flowers exhibiting two-coloured petals, i.e. the margin is coloured differently than the central zone, characterize one of the sport types, namely picotees. This particular sporting type contributes to the enlargement of the available variation not only because of its coloration pattern but interestingly displays somatic polyploidy in its petals. The differently coloured petal margin is tetraploid while the rest of the corolla, as well as the entire plant are diploid. Aiming at introducing polyploidy in the completely diploid breeding collection, in vitro regeneration of tetraploid petal marginal tissue was performed. This led to the production of the first induced tetraploid Belgian azalea. The markedly increased robustness of the flowers as well as their polyploid status is exceptionally interesting for breeding programs.

Somatic polyploid petals: regeneration offers new roads for breeding Belgian pot azaleas

Flower colour variegation is not only a phenomenon of importance to horticulture, the phenotype involved is also often used as a scientific model system for the study of complex gene regulation processes. In the course of such studies on azalea, we observed a correlation between flower colour patterns, flower morphology and somatic polyploidy. Using high-resolution flow cytometry of nuclear DNA, the ploidy level was determined in flowers of different azalea sport families. Sports exhibiting variegated flowers with broad (>7 mm), differently coloured, petal edges (picotee type) proved to be tetraploid in the petal edge but diploid in the rest of the flower tissue. Neither flower colour pattern nor ploidy differences are periclinal chimeric in origin, but seem to be correlated with the topographic location of the cells within the flower tissue, i.e. the margin of the petals. The possible role of gene dosage effects and cell size involved in the remarkable correlation between somatic polyploidy, (flavonoid) gene expression and flower morphology is discussed.

Somatic polyploidy and its consequences for flower coloration and flower morphology in azalea

The presence of liquid hydrocarbon droplets in the convection section of a steam cracker may cause serious fouling problems due to coke formation, especially in high temperature zones. In order to investigate these fouling problems, a model has been developed and implemented in a CFD code to accurately simulate the behavior of a hydrocarbon droplet impinging on a hot surface. The impact energy of the droplet and the hot surface temperature are found to determine the impact behavior. On the basis of the newly developed model, the positions where droplets preferentially collide with the convection section tube walls and liquid material is deposited are determined. Furthermore, a kinetic model describing coke formation out of liquid hydrocarbon droplets in the temperature range of 450−700 K has been developed to calculate the rate of coke formation in each zone of the convection section tube. The calculated coke layer thickness on the most vulnerable tube locations and the industrially available values corre...

Sandra De Schepper

Papers

Modeling the evaporation of a hydrocarbon feedstock in the convection section of a steam cracker

CFD modeling of all gas–liquid and vapor–liquid flow regimes predicted by the Baker chart

Somatic polyploid petals: regeneration offers new roads for breeding Belgian pot azaleas

Somatic polyploidy and its consequences for flower coloration and flower morphology in azalea

Modeling the Coke Formation in the Convection Section Tubes of a Steam Cracker