When plants are exposed to light intensities in excess of those that can be utilized in photosynthetic electron transport, nonphotochemical dissipation of excitation energy is induced as a mechanism for photoprotection of photosystem II. The features of this process are reviewed, particularly with respect to the molecular mechanisms involved. It is shown how the dynamic properties of the proteins and pigments of the chlorophyll a/b light-harvesting complexes of photosystem II first enable the level of excitation energy to be sensed via the thylakoid proton gradient and subsequently allow excess energy to be dissipated as heat by formation of a nonphotochemical quencher. The nature of this quencher is discussed, together with a consideration of how the variation in capacity for energy dissipation depends on specific features of the composition of the light-harvesting system. Finally, the prospects for future progress in understanding the regulation of light harvesting are assessed.

Reduced lung function predicts mortality and is key to the diagnosis of chronic obstructive pulmonary disease (COPD). In a genome-wide association study in 400,102 individuals of European ancestry, we define 279 lung function signals, 139 of which are new. In combination, these variants strongly predict COPD in independent patient populations. Furthermore, the combined effect of these variants showed generalizability across smokers and never-smokers, and across ancestral groups. We highlight biological pathways, known and potential drug targets for COPD and, in phenome-wide association studies, autoimmune-related and other pleiotropic effects of lung function associated variants. This new genetic evidence has potential to improve future preventive and therapeutic strategies for COPD.

It has long been recognized that higher plants vary the composition and organization of the photosynthetic apparatus in response to the prevailing environmental conditions, with particular attention being paid to the responses to incident light. Under high light conditions there are increases in the amounts of photosystems, electron transport and ATP synthase complexes, and enzymes of the Calvin-Benson cycle; conversely, under low light there is an increase in the relative amounts of light-harvesting complexes (LHC) and in the stacking of thylakoid membranes to form grana. It is believed that these changes are of adaptive significance, and in a few instances evidence has been provided that this is indeed the case; an increase in photosynthetic capacity reduces susceptibility to photodamage, while changes in photosystem stoichiometry serve to optimize light utilization. By contrast, the potential benefit to the plant of other changes in chloroplast composition, such as in the levels of LHC, is far less clear. It is also believed that redox signals derived from photosynthetic electron transport play an important regulatory role in acclimation. However, while there is convincing evidence that such redox signals modulate the expression of many plastidic and nuclear genes encoding photosynthetic components, there is little to demonstrate that such changes are responsible for regulating chloroplast composition. This review discusses the evidence that particular aspects of acclimation are advantageous to the plant, and highlights the significant gaps in our understanding of the mechanisms underlying acclimation.

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Both underweight and obesity have been associated with increased mortality1,2. Underweight, defined as body mass index (BMI) ≤ 18,5 kg/m2 in adults 3 and ≤ −2 standard deviations (SD) in children4,5, is the main sign of a series of heterogeneous clinical conditions such as failure to thrive (FTT) 6–8, feeding and eating disorder and/or anorexia nervosa9,10. In contrast to obesity, few genetic variants underlying these clinical conditions have been reported 11, 12. We previously demonstrated that hemizygosity of a ~600 kb region on the short arm of chromosome 16 (chr16:29.5–30.1Mb), causes a highly-penetrant form of obesity often associated with hyperphagia and intellectual disabilities13. Here we show that the corresponding reciprocal duplication is associated with underweight. We identified 138 (132 novel cases) duplication carriers (108 unrelated carriers) from over 95,000 individuals clinically-referred for developmental or intellectual disabilities (DD/ID), psychiatric disorders or recruited from population-based cohorts. These carriers show significantly reduced postnatal weight (mean Z-score −0.6; p=4.4×10−4) and BMI (mean Z-score −0.5; p=2.0×10−3). In particular, half of the boys younger than 5 years are underweight with a probable diagnosis of FTT, while adult duplication carriers have an 8.7-fold (p=5.9×10−11; CI_95=[4.5–16.6]) increased risk of being clinically underweight. We observe a significant trend towards increased severity in males, as well as a depletion of male carriers among non-medically ascertained cases. These features are associated with an unusually high frequency of selective and restrictive feeding behaviours and a significant reduction in head circumference (mean Z-score −0.9; p=7.8×10−6). Each of the observed phenotypes is the converse of one reported in carriers of deletions at this locus, correlating with changes in transcript levels for genes mapping within the duplication but not within flanking regions. The reciprocal impact of these 16p11.2 copy number variants suggests that severe obesity and being underweight can have mirror etiologies, possibly through contrasting effects on eating behaviour.