Plant phototropism is an adaptive response to changes in light direction, quantity, and quality that results in optimization of photosynthetic light harvesting, as well as water and nutrient acquisition. Though several components of the phototropic signal response pathway have been identified in recent years, including the blue light (BL) receptors phototropin1 (phot1) and phot2, much remains unknown. Here, we show that the phot1-interacting protein NONPHOTOTROPIC HYPOCOTYL3 (NPH3) functions as a substrate adapter in a CULLIN3-based E3 ubiquitin ligase, CRL3 NPH3 . Under low-intensity BL, CRL3 NPH3 mediates the mono/multiubiquitination of phot1, likely marking it for clathrin-dependent internalization from the plasma membrane. In high-intensity BL, phot1 is both mono/multi-and polyubiquitinated by CRL3 NPH3 , with the latter event targeting phot1 for 26S proteasome-mediated degradation. Polyubiquitination and subsequent degradation of phot1 under high-intensity BL likely represent means of receptor desensitization, while mono/multiubiquitination-stimulated internalization of phot1 may be coupled to BL-induced relocalization of hormone (auxin) transporters.

Few individuals have had the lasting impact on such a breadth of science as Charles Darwin. While his writings about time aboard the HMS Beagle, his study of the Galapagos islands (geology, fauna, and flora), and his theories on evolution are well known, less appreciated are his studies on plant growth responses to a variety of environmental stimuli. In fact, Darwin, together with the help of his botanist son Francis, left us an entire book, 'The power of movements in plants', describing his many, varied, and insightful observations on this topic. Darwin's findings have provided an impetus for an entire field of study, the study of plant tropic responses, or differential growth (curvature) of plant organs in response to directional stimuli. One tropic response that has received a great deal of attention is the phototropic response, or curvature response to directional light. This review summarizes many of the most significant advancements that have been made in our understanding of this response and place these recent findings in the context of Darwin's initial observations.

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Field observations on the behaviour of adult Galapagos giant tortoises (Geochehne elephantopus) on the islands of Santa Cruz (Indefatigable) and Pinzon (Duncan) were made by the 1972 Expedition, and on Santa Cruz by the 1973 Expedition. The animals (in all 14 on Santa Cruz and three on Pinzon) were observed continuously throughout the day for periods of 3–14 days so that their main non‐reproductive activities (feeding and walking) could be quantitatively recorded. The period of potential activity was between about 08.00 hrs and 16.00–18.00 hrs, but the pattern of behaviour was extremely variable, both in a given individual and between one individual and another; it seemed little influenced by the relatively slight fluctuations of temperature and climate which occurred during the period of study (July‐September) on Santa Cruz. The tortoises on Pinzon, a much more arid island, were less active, and one showed a strongly bimodal activity pattern with a resting period during the middle of the day. The animals studied in 1972 showed a strong disposition to return after several days to the same sleeping place, but this homing tendency was not observed in 1973. This discrepancy can perhaps be attributed to the fact that the two expeditions worked in different areas under different weather conditions. Observations on the plants eaten, on the association between tortoises and certain birds, and on some other aspects of tortoise behaviour such as walking speed and responses to sounds are also described.

Immune cells display multiple cell surface receptors that integrate signals for survival, proliferation, migration, and degranulation. Here, immunogold labeling is used to map the plasma membrane distributions of two separate receptors, the N-formyl peptide receptor (FPR) and the high-affinity IgE receptor (FRI). We show that the FPR forms signaling clusters in response to monovalent ligand. These domains recruit