Colorless phenylpropanoid derivatives are known to protect plants from ultraviolet (UV) radiation, but their photoregulation and physiological roles under field conditions have not been investigated in detail. Here we describe a fast method to estimate the degree of UV penetration into photosynthetic tissue, which is based on chlorophyll fluorescence imaging. In Arabidopsis this technique clearly separated the UV-hypersensitive transparent testa (tt) tt5 and tt6 mutants from the wild type (WT) and tt3, tt4, and tt7 mutants. In field-grown soybean (Glycine max), we found significant differences in UV penetration among cultivars with different levels of leaf phenolics, and between plants grown under contrasting levels of solar UV-B. The reduction in UV penetration induced by ambient UV-B had direct implications for DNA integrity in the underlying leaf tissue; thus, the number of cyclobutane pyrimidine dimers caused by a short exposure to solar UV-B was much larger in leaves with high UV transmittance than in leaves pretreated with solar UV-B to increase the content phenylpropanoids. Most of the phenylpropanoid response to solar UV in field-grown soybeans was induced by the UV-B component ( < 315 nm). Our results indicate that phenolic sunscreens in soybean are highly responsive to the wavelengths that are most affected by variations in ozone levels, and that they play an important role in UV protection in the field.

Far-red radiation (FR) reflected by green tissues is a key signal that plants use to detect the proximity of future competitors. Perception of increased levels of FR elicits a suite of responses collectively known as the shade-avoidance syndrome, whic

The prevalence of obesity in some lower-income and transitional countries is as high as, or even higher than, the prevalence reported in developed nations, and it seems to be increasing rapidly. In most countries, the prevalence of obesity is higher in women than in men, and higher in urban than in rural areas. Preobesity prevalence is very high in most Latin-American countries. Sixty per cent of the population in Venado Tuerto (Argentina) has a body mass index (BMI) of > or = 25 kg m-2, as do 35% of the population in Brazil, 60% in Mexico, 68% in Paraguay and 53% in Peru. Trends are available from Brazil, where marked increases in the prevalence of obesity have occurred, except in women from higher-income groups. Women from the higher-income quartiles in urban regions experienced a marked reduction in obesity prevalence from 1989 to 1997 (12.8 to 9.2%). Although data in children is scant, the prevalence of undernutrition is decreasing and the prevalence of obesity is high also in Latin-American children. The prevalence of obesity is high even in minority Indian groups. Rapid changes in dietary structure (in particular associated with urbanization) and major changes in the levels of physical activity, both occupationally and during leisure time, may explain these changes.

OBJECTIVEOur objective was to characterize diabetes-specific health-related quality of life (D-HRQOL) in a global sample of youth and young adults with type 1 diabetes (T1D) and to identify the main factors associated with quality of life.RESEARCH DESIGN AND METHODSThe TEENs study was an international, cross-sectional study of youth, 8–25 years of age, with T1D. Participants (N = 5,887) were seen in clinical sites in 20 countries across 5 continents enrolled for 3 predetermined age groups: 8–12, 13–18, and 19–25 years of age. To assess D-HRQOL, participants completed the PedsQL Diabetes Module 3.0 and were interviewed about family-related factors. Specifics about treatment regimen and self-management behaviors were collected from medical records.RESULTSAcross all age groups, females reported significantly lower D-HRQOL than did males. The 19–25-year age group reported the lowest D-HRQOL. Multivariate linear regression analyses revealed that D-HRQOL was significantly related to HbA1c; the lower the HbA1c, the better the D-HRQOL. Three diabetes-management behaviors were significantly related to better D-HRQOL: advanced methods used to measure food intake; more frequent daily blood glucose monitoring; and more days per week that youth had ≥30 min of physical activity.CONCLUSIONSIn all three age groups, the lower the HbA1c, the better the D-HRQOL, underscoring the strong association between better D-HRQOL and optimal glycemic control in a global sample of youth and young adults. Three diabetes-management behaviors were also related to optimal glycemic control, which represent potentially modifiable factors for clinical interventions to improve D-HRQOL as well as glycemic control.

The results suggest that the anti-herbivory effect induced by UV-B may be mediated at least in part by the accumulation of phenylpropanoid derivatives that are similar to those induced by the plant in response to insect herbivory.

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Most of our present knowledge about the impacts of solar UVB radiation on terrestrial ecosystems comes from studies with plants. Recently, the effects of UVB on the growth and survival of consumer species have begun to receive attention, but very little is known about UVB impacts on animal behavior. Here we report that manipulations of the f lux of solar UVB received by field-grown soybean crops had large and consistent effects on the density of the thrips (Caliothrips phaseoli, Thysanoptera: Thripidae) populations that invaded the canopies, as well as on the amount of leaf damage caused by the insects. Solar UVB strongly reduced thrips herbivory. Thrips not only preferred leaves from plants that were not exposed to solar UVB over leaves from UVBexposed plants in laboratory and field choice experiments, but they also appeared to directly sense and avoid exposure to solar UVB. Additional choice experiments showed that soybean leaf consumption by the late-season soybean worm Anticarsia gemmatalis (Lepidoptera: Noctuidae) was much less intense in leaves with even slight symptoms of an early thrips attack than in undamaged leaves. These experiments suggest that phytophagous insects can present direct and indirect behavioral responses to solar UVB. The indirect responses are mediated by changes in the plant host that are induced by UVB and, possibly, by other insects whose behavior is affected by UVB.Depletion of stratospheric ozone (1) is a cause of concern because the biological impacts of an increase in solar UVB (290-320 nm) are unknown. Most studies to date on ecological effects of solar UVB have been carried out on plants (2-4); however, there is growing awareness in the UVB research community (2-7), as well as among those studying other aspects of global environmental change (8), about the limitations of impact predictions that result from up-scaling information obtained in studies of a single organism or trophic level. The concentration of the research effort on plants is in part a consequence of the assumption that the effects of UVB on ecosystem functioning are largely mediated by its effects on the primary producers (6).Recent studies on animal consumers have focused on those effects of UVB on consumer growth and survival that are mediated by changes in host chemistry (9-11) and on direct damaging effects of UVB. In the latter regard, it has been shown that certain animal species (particular instars), such as juvenile forms of some aquatic organisms, are not well protected from UV radiation and are damaged by prolonged exposure to present-day levels of UVA (320-400 nm) and UVB (4, 12, 13) radiation. Damaging effects of acute exposures on zooplanktonic organisms have also been documented in studies carried out in Antarctic waters under ozone-hole episodes (14). Interestingly, one of the few studies that included more than one trophic level has shown that direct damaging effects of solar UV radiation on phytophagous insect larvae can counterbalance the negative impact of UV on algal photosynthesis an...

One of the principal internal signals controlling plant growth and defense is jasmonate (JA), a potent growth inhibitor that is simultaneously a central regulator of plant immunity to herbivores and pathogens. When shade-intolerant plants perceive the proximity of competitors using the photoreceptor phytochrome B (phyB), they accelerate growth and down-regulate JA responses. However, the mechanisms by which photoreceptors relay light