Perception of Sunflecks by the UV-B Photoreceptor UV RESISTANCE LOCUS8

Sunflecks, transient patches of light that penetrate through gaps in the canopy and transiently interrupt shade, are eco-physiologically and agriculturally important sources of energy for carbon gain, but our molecular understanding of how plant organs perceive and respond to sunflecks through photoreceptors remains limited. The UV-B photoreceptor UV RESISTANCE LOCUS8 (UVR8) is a recent addition to the list of plant photosensory receptors, and we have made considerable advances in our understanding of the physiology and molecular mechanisms of action of UVR8 and its signaling pathway. However, the function of UVR8 in the natural environment is poorly understood. Here, we show that the UVR8 dimer/monomer ratio responds quantitatively and reversibly to the intensity of sunflecks that interrupt shade in the field. Sunflecks reduced hypocotyl growth and increased CHALCONE SYNTHASE (CHS) and ELONGATED HYPOCOTYL5 gene expression and CHS protein abundance in wild-type Arabidopsis (Arabidopsis thaliana) seedlings, but the uvr8 mutant was impaired in these responses. UVR8 was also required for normal nuclear dynamics of CONSTITUTIVELY PHOTOMORPHOGENIC1. We propose that UVR8 plays an important role in the plant perception of and response to sunflecks.

LOV-domain photoreceptor, encoded in a genomic island, attenuates the virulence of Pseudomonas syringae in light-exposed Arabidopsis leaves

In Arabidopsis thaliana, light signals modulate the defences against bacteria. Here we show that light perceived by the LOV domain-regulated two-component system (Pst-Lov) of Pseudomonas syringae pv. tomato DC3000 (Pst DC3000) modulates virulence against A. thaliana. Bioinformatic analysis and the existence of an episomal circular intermediate indicate that the locus encoding Pst-Lov is present in an active genomic island acquired by horizontal transfer. Strains mutated at Pst-Lov showed enhanced growth on minimal medium and in leaves of A. thaliana exposed to light, but not in leaves incubated in darkness or buried in the soil. Pst-Lov repressed the expression of principal and alternative sigma factor genes and their downstream targets linked to bacterial growth, virulence and quorum sensing, in a strictly light-dependent manner. We propose that the function of Pst-Lov is to distinguish between soil (dark) and leaf (light) environments, attenuating the damage caused to host tissues while releasing growth out of the host. Therefore, in addition to its direct actions via photosynthesis and plant sensory receptors, light may affect plants indirectly via the sensory receptors of bacterial pathogens.

Evaluation of new computerized method for recording 7-day food intake in IDDM patients

OBJECTIVE

To evaluate a new computerized method for recording 7-day food intake.

RESEARCH DESIGN AND METHODS

Randomized crossover trial was conducted with patients recording the amount and type of every food and drink consumed during a week by either a computerized device (Food-meter) or recording the data in a diary. Each method was applied twice. Twenty-one insulin-dependent diabetic patients (mean +/- SD age 25 +/- 9 yr) were studied.

RESULTS

The two methods showed very good agreement in the evaluation of the patients' diets (1792 +/- 408 vs. 1764 +/- 436 kcal/day, 84 +/- 19 vs. 82 +/- 21 g/day protein, 68 +/- 22 vs. 67 +/- 23 g/day fat, 210 +/- 60 vs. 207 +/- 58 g/day carbohydrate with the conventional and computerized methods, respectively). The variability between the methods and the variability within each method were of similar magnitude.

CONCLUSIONS

The Food-meter represents a useful tool for computerizing the 7-day food record. The method is easy, reliable, and time saving. Moreover, it minimizes the risk of transcriptional errors.

[A new proposal for nutritional education in a group of obese adolescents]

A new "active" system of monitoring and dietary education was experimented in a group of 20 obese adolescents waiting to start diet therapy. Each subject was requested to record all food and drink consumed during two separate periods, each lasting 7 days, at a distance of 15 days from each other, at home using an optic reader and book of bar codes. On the basis of answers to a questionnaire which was completed at the beginning and end of the study, aimed at assessing the level of knowledge of basic food hygiene, the majority of participants considered the experience useful and amusing and were willing to repeat it; in addition, a greater knowledge of nutritional principles and of the rations consumed was shown at the end of the study. The results of the study were analysed using the Food Meter-Miles computerised system and showed daily calorie intakes of 1514 +/- 524.0, M +/- DS (protein 18.3 +/- 5.1%, lipids 33.7 +/- 6.2%, glucose 47.9 +/- 8.6%, total fibre 14.4 +/- 4.6 g) in female subjects, and 2096.1 +/- 80.8 (protein 16.1 +/- 3.6%, lipids 38.2 +/- 2.9%, glucose 45.7 +/- 3.9%, total fibre 18.1 +/- 2.0 g) in male subjects. The number of foods chosen was very low considering the range of foods available (277) and the length of time studied: 35.7 +/- 11.8 and 35.0 +/- 6.0 respectively for female and male subjects. With regard to the number and type of meals eaten, a high number of snacks was observed which supplemented or replaced main meals.