Cytokinin replaces light in several aspects of the photomorphogenesis of dicot seedlings. Arabidopsis thaliana seedlings grown under red light have been shown to become disoriented, losing the negative hypocotyl gravitropism that has been observed in seedlings grown in darkness or white light. We report here that cytokinin at micromolar concentrations restores gravitropism to seedlings grown under red light. Cytokinin cancels the effect of red light on the gravity-sensing system and at the same time replaces light in the inhibition of hypocotyl elongation. Furthermore, application of the ethylene precursor 1 -aminocyclopropane-I -carboxylic acid acts similarly to cytokinin. Cytokinin cannot restore gravitropism under red light to an ethylene-insensitive mutant that is defective at the NN2 locus. Stimulation of ethylene production, therefore, can explain the action of cytokinin in restoring negative gravitropism to the hypocotyls of Arabidopsis seedlings grown under continuous red light.

Treating cancer is one of the major challenges of modern medicine. Since mice models are an important tool in cancer treatment research, it is required to assess murine tumor development. Existing methods for investigating tumor development are either high cost and limited by their availability or suffer from low accuracy and reproducibility. In order to overcome these drawbacks, thermography may be used. DA3 breast cancer carcinoma tumors in 12 Balb/c mice were thermally imaged and monitored for a period of several weeks. Eight mice were treated with diffusing alpha emitters radiation therapy (DaRT) wires, while four were treated with inert wires. For large tumors, the area was estimated by analyzing thermal images and was found to be in correlation with manual caliper measurements. In addition, the correlation between tumor area and relative temperatures was calculated and compared to previous works. Temperature differences were larger for tumors treated with DaRT wires than tumors with inert wires. These correlations can be used to assist in tumor size estimation and reveal information regarding its metabolic state. Overall, thermography was shown to be a promising tool for assessing tumor development with the additional advantages of being nonradiative and potentially providing indication of intratumoral biological processes.

Continuous monitoring of tumor temperature difference produces valuable information on tumor state and aggressiveness that can be used both in the clinic and in the laboratory. Monitoring can be either performed on a single image, or continuous on multiple images, revealing changes in tumor state.

No abstract