When a plant is rotated on a clinostat, with its axis parallel to the ground, the axis may remain straight. According to Sachs (9), the successive stimuli of gravity compensate each other and, therefore, there is no tropic reaction. Czapek (4) on the other hand, felt that under these conditions, there is no perception of the gravity by the plant and consequently no tropic reaction. In connectio...

Leaf resistance for water vapor (total diffusion resistance minus boundary layer resistance), transpiration, and leaf temperature were measured in attached leaves of greenhouse-grown Xanthium strumarium L. plants that had been pretreated for 72 hours with high (40 C day, 35 C night), or low (10 C day, 5 C night) air temperatures. Measurements were made in a wind tunnel at light intensity of 1.1...

The extraction procedures which have been successfully employed in the preparation of a florigenic principle from the tissues of Xanthium, are applicable to the derivation of an entity of similar activity from Calonectria culture. The Xanthium principle is acedic, with pK(a) values characteristic of a carboxylic acid (6). Although definitive chemical comparisons have not been completed, the ext...

The antiplasmodial active extract of Xanthium cavanillesii contains 3,4-dicaffeoyl quinic acid (3,4-DCQA), 3,5-dicaffeoyl quinic acid (3,5-DCQA) and 1,3,5-tricaffeoyl quinic acid (1,3,5-TCQA). These results inspired us to investigate the interaction of these molecules with a promising validated target of Plasmodium, PfATP6 orthologue of mammalian Ca+2-ATPase. Models of this receptor were obtain...

It has been shown previously ( 15) that photoperiodic induction in Xanthium is inhibited by application of the pyrimidine, 5-fluorouracil (5-FU). More recently (1) it has been demonstrated that the process which is inhibited by 5-FU and which is related to the process of flowering, is the synthesis of ribonucleic acid (RNA) in the Xanthium bud during the first part of the inductive dark period....

Efeito de métodos de extração de compostos fenólicos de Xanthium strumarium L. e suas atividades antioxidantes. The effect of extraction methods and solvents on overall yield, total phenolic content, antioxidant activity, and the composition of the phenolic compounds in Xanthium strumarium extracts were studied. The antioxidant activity was determined by using 2,2-diphenyl-1-picrylhydrazyl radi...