Quelques effets du β-mercaptoéthanol et du dithiodiglycol sur la régénération

The effects of β-mercaptoethanol and dithiodiglycol (the former containing an -SH group and the latter an -SS- group) on regeneration have been studied in five animal species. Mercaptoethanol inhibits regeneration while dithiodiglycol (at those concentrations at which it can be employed) has almost no effect.Mercaptoethylgluconamide, a derivate of mercaptoethanol, cannot penetrate into the cells and it has no noticeable influence on regeneration, except at extremely high concentrations.Mercaptoethanol moderately reduces mitotic activity and basophilia in the blastema. However, it stimulates the synthesis of RNA without acting on DNA synthesis.Dithiodiglycol does not modify mitotic activity, but it increases slightly the basophilia of the regenerating tissue. It also stimulates RNA synthesis.These results are discussed.     

Le test de génération de thrombine Un test utile pour la recherche et nécessaire pour une exploration moderne de l’hémostase

The thrombin generation assay has been used for many years, and its methods of use have been especially improved. The kinetic determination of thrombin generation using calibrators and specific substrates in platelet-poor and platelet-rich plasma, associated with the computerized determination of different parameters, breathes a new life into this test. After standardization, its promising clinical and research applications must be confirmed on a wide scale.     

Effet de l'osmolarité et de la composition du milieu sur la callogénèse,la caulogénèse et la rhizogénèse de fragments d'hypocotyles deBrassica oleracea L. var.botrytis

Callus formation by fragments of cauliflower hypocotyls was favoured by raising culture medium osmolarity above ?0.38 MPa. Increase in sucrose concentration while diminishing macronutrients inhibited callus initiation and growth. Root formation by the same material required a low medium osmolarity (?0.19 MPa). Reducing sucrose concentration in the classical Murashige and Skoog rooting culture medium favoured root formation. Adventitious bud formation was also depending upon medium osmolarity besides the need for a cytokinin. Reducing too much the osmotic potential of the medium had an unfavourable effect on bud neoformation. The importance of sucrose in all these processes is pointed out.