Effect of cytosine hydroxymethylation on DNA charge transport

Molecular and Cellular Biochemistry - DNA hydroxymethylation plays a very important role in some biological processes, such as DNA methylation process. In addition, its presence can also cause some...     

<Emphasis Type="Italic">In vitro</Emphasis> selection and regeneration of chrysanthemum (<Emphasis Type="Italic">Dendranthema grandiflorum</Emphasis> Tzelev) plants resistant to culture filtrate of <Emphasis Type="Italic">Septoria obesa</Emphasis> Syd

Callus cultures derived from leaf segments of chrysanthemum cultivar ‘Snow Ball’ which was susceptible to Septoria obesa were successfully used for in vitro selection for resistance to this pathogenic fungus. Resistant cell lines were selected by culturing callus on growth medium containing various concentrations of S. obesa filtrate. Resistant calluses obtained after two cycles (30 d each cycle) of selection were used for plant regeneration. About 30% of the plants regenerated from the resistant calluses and 70–80% of the plants raised from cuttings had acquired considerable resistance against the pathogen in the field. No phenotypic variation was observed in the selected regenerates.     

Relaxin's induction of metalloproteinases is associated with the loss of collagen and glycosaminoglycans in synovial joint fibrocartilaginous explants

Diseases of specific fibrocartilaginous joints are especially common in women of reproductive age, suggesting that female hormones contribute to their etiopathogenesis. Previously, we showed that relaxin dose-dependently induces matrix metalloproteinase (MMP) expression in isolated joint fibrocartilaginous cells. Here we determined the effects of relaxin with or without β-estradiol on the modulation of MMPs in joint fibrocartilaginous explants, and assessed the contribution of these proteinases to the loss of collagen and glycosaminoglycan (GAG) in this tissue. Fibrocartilaginous discs from temporomandibular joints of female rabbits were cultured in medium alone or in medium containing relaxin (0.1 ng/ml) or β-estradiol (20 ng/ml) or relaxin plus β-estradiol. Additional experiments were done in the presence of the MMP inhibitor GM6001 or its control analog. After 48 hours of culture, the medium was assayed for MMPs and the discs were analyzed for collagen and GAG concentrations. Relaxin and β-estradiol plus relaxin induced the MMPs collagenase-1 and stromelysin-1 in fibrocartilaginous explants – a finding similar to that which we observed in pubic symphysis fibrocartilage, but not in articular cartilage explants. The induction of these proteinases by relaxin or β-estradiol plus relaxin was accompanied by a loss of GAGs and collagen in joint fibrocartilage. None of the hormone treatments altered the synthesis of GAGs, suggesting that the loss of this matrix molecule probably resulted from increased matrix degradation. Indeed, fibrocartilaginous explants cultured in the presence of GM6001 showed an inhibition of relaxin-induced and β-estradiol plus relaxin-induced collagenase and stromelysin activities to control baseline levels that were accompanied by the maintenance of collagen or GAG content at control levels. These findings show for the first time that relaxin has degradative effects on non-reproductive synovial joint fibrocartilaginous tissue and provide evidence for a link between relaxin, MMPs, and matrix degradation.