A dramatic increase of chlorophyll (Chl) degradation occurs during senescence of vegetative plant organs and fruit ripening. Although the biochemical pathway of Chl degradation has long been proposed, little is known about its regulatory mechanism. Identification of Chl degradation-disturbed mutants and subsequently isolation of responsible genes would greatly facilitate the elucidation of the regulation of Chl degradation. Here, we describe a nonyellowing mutant of Arabidopsis (Arabidopsis thaliana), nye1-1, in which 50% Chl was retained, compared to less than 10% in the wild type (Columbia-0), at the end of a 6-d dark incubation. Nevertheless, neither photosynthesis-nor senescence-associated process was significantly affected in nye1-1. Characteristically, a significant reduction in pheophorbide a oxygenase activity was detected in nye1-1. However, no detectable accumulation of either chlorophyllide a or pheophorbide a was observed. Reciprocal crossings revealed that the mutant phenotype was caused by a monogenic semidominant nuclear mutation. We have identified AtNYE1 by positional cloning. Dozens of its putative orthologs, predominantly appearing in higher plant species, were identified, some of which have been associated with Chl degradation in a few crop species. Quantitative polymerase chain reaction analysis showed that AtNYE1 was drastically induced by senescence signals. Constitutive overexpression of AtNYE1 could result in either pale-yellow true leaves or even albino seedlings. These results collectively indicate that NYE1 plays an important regulatory role in Chl degradation during senescence by modulating pheophorbide a oxygenase activity.

Tall fescue (Festuca arundinacea Schreb.) is a cool-season perennial grass, which has been conventionally grown in the temperate area. However, as a major type of cool-season turf grass, its growth has been extended to the sub-tropical climate or even to the transitional climate between the sub-tropical and the tropical, and, in some cases, to heavily salinized lands. The extended growth imposes a serious challenge to its tolerance to the abiotic stress, particularly to drought, salt and high temperature. Here, we report a successful introduction of Arabidopsis AtHDG11 into the tall fescue via Agrobacterium-mediated transformation. The ectopic overexpression of AtHDG11 under the control of CaMV 35S promoter with four enhancers resulted in significantly enhanced tolerance to drought and salt stress. No obvious adverse effects on growth and development were observed in the transgenic plants. The enhanced stress tolerance was associated with a more extensive root system, a lower level of malondialdehyde, a nearly normal Na(+)/K(+) ratio, a higher level of proline and a kinetically accelerated induction of SOD and CAT activities observed in the transgenic plants during drought and/or salt stress, indicating that an enhanced ROS scavenging capability might play a significant role in the acquired tolerance to the abiotic stress.

Supplement of ABM extract improves insulin resistance among subjects with type 2 diabetes. The increase in adiponectin concentration after taking AMB extract for 12 weeks might be the mechanism that brings the beneficial effect. Studies with longer periods of follow-up should be conducted in the future.

The relatively low density of functional groups of graphene oxide (GO) and the difficulty to completely recover after adsorption limit its application in uranium (U­(VI)) removal from aqueous solution. Inspired by a special chemical property, polydopamine (PDA) was first used as a surface modifying agent for GO, and then the as-formed GO@PDA cross-linked with chitosan (CS) to assemble a three-dimensional (3D) porous GO@PDA/CS aerogel for U­(VI) adsorption. Morphology and structure of the aerogel were characterized by TEM, SEM, FTIR, XPS, XRD, Raman, and TGA. The results show that compared to GO/CS, the GO@PDA/CS aerogel possesses a more homogeneous and well-organized 3D porous structure as well as the enhanced active sites, which are beneficial for U­(VI) removal. According to batch experiments, the adsorption rate of the GO@PDA/CS aerogel was very fast, and the adsorption equilibrium could be reached in 15 min at pH = 6.0. Its maximum adsorption capacity for U­(VI) is as high as 415.9 mg g–1 at 298 K calculated from the Langmuir model. In addition, the as-prepared GO@PDA/CS aerogel exhibits satisfactory thermal and mechanical stability and could be recycled six times without an apparent decrease in removal efficiency.