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"Yuan, Yao"
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Repressors of anthocyanin biosynthesis
Anthocyanins play a variety of adaptive roles in both vegetative tissues and reproductive organs of plants. The broad functionality of these compounds requires sophisticated regulation of the anthocyanin biosynthesis pathway to allow proper localization, timing, and optimal intensity of pigment deposition. While it is well-established that the committed steps of anthocyanin biosynthesis are activated by a highly conserved MYB-bHLH-WDR (MBW) protein complex in virtually all flowering plants, anthocyanin repression seems to be achieved by a wide variety of protein and small RNA families that function in different tissue types and in response to different developmental, environmental, and hormonal cues. In this review, we survey recent progress in the identification of anthocyanin repressors and the characterization of their molecular mechanisms. We find that these seemingly very different repression modules act through a remarkably similar logic, the so-called ‘double-negative logic’. Much of the double-negative regulation of anthocyanin production involves signal-induced degradation or sequestration of the repressors from the MBW protein complex. We discuss the functional and evolutionary advantages of this logic design compared with simple or sequential positive regulation. These advantages provide a plausible explanation as to why plants have evolved so many anthocyanin repressors.
Journal Article
Transcriptional Regulation of Carotenoid Biosynthesis in Plants: So Many Regulators, So Little Consensus
In plants, the carotenoid biosynthesis pathway (CBP) is essential for the production of photosynthetic and protective pigments, plant hormones, and visual/olfactory attractants for animal pollinators and seed dispersers. The regulation of carotenoid biosynthesis at the transcriptional level is vitally important for all of these functions and has been the subject of intensive research. Many putative transcriptional regulators, both direct and indirect, have been identified through conventional mutant analysis, transcriptome profiling, yeast one-hybrid screening, and candidate gene approaches. Despite this progress, our understanding of the transcriptional regulation of carotenoid biosynthesis remains fragmented and incomplete. Frequently, a stimulus or regulator is known, but the mechanism by which it affects transcription has not been elucidated. In other cases, mechanisms have been proposed (such as direct binding of a CBP gene promoter by a transcription factor), but function was tested only
or in heterologous systems, making it unclear whether these proteins actually play a role in carotenoid regulation in their endogenous environments. Even in cases where the mechanism is relatively well understood, regulators are often studied in isolation, either in a single plant species or outside the context of other known regulators. This presents a conundrum: why so many candidate regulators but so little consensus? Here we summarize current knowledge on transcriptional regulation of the CBP, lay out the challenges contributing to this conundrum, identify remaining knowledge gaps, and suggest future research directions to address these challenges and knowledge gaps.
Journal Article
Ancient city walls in China : a heritage rediscovered
\"In numerous civilizations throughout world history city walls were an indispensable part of every city. In China they can be traced back to the 21th century BC as fortified symbols of power and manifestation of the Middle Kingdom. In the course of the country's long history several thousand have been erected, varying enormously in form, length, construction technology, functionality and significance. These city walls represent a unique heritage and a central identification factor from which to gain access to the self-image of Chinese culture. After years of decay and ignorance, it was only a few decades ago that they were discovered as cultural monuments and the securing and restoration work began. The city walls recorded in the statistics today, of which a selection is presented in this book by new and historic photos, range from wall ruins in the ground via about 150 with a length of more than one kilometer to the famous fortification of Nanjing, which still has more than 20 kilometers standing.\" -- amazon
Book
How does COVID-19 affect the life cycle environmental impacts of U.S. household energy and food consumption?
The COVID-19 pandemic has reduced travel but led to an increase in household food and energy consumption. Previous studies have explored the changes in household consumption of food and energy during the pandemic; however, the economy-wide environmental implications of these changes have not been investigated. This study addresses the knowledge gap by estimating the life cycle environmental impacts of U.S. households during the pandemic using a hybrid life cycle assessment. The results revealed that the reduction in travel outweighed the increase in household energy consumption, leading to a nationwide decrease in life cycle greenhouse gas emissions (−255 Mton CO 2 eq), energy use (−4.46 EJ), smog formation (−9.17 Mton O 3 eq), minerals and metal use (−16.1 Mton), commercial wastes (−8.31 Mton), and acidification (−226 kton SO 2 eq). However, U.S. households had more life cycle freshwater withdrawals (+8.6 Gton) and slightly higher eutrophication (+0.2%), ozone depletion (+0.7%), and freshwater ecotoxicity (+2.1%) caused by increased household energy and food consumption. This study also demonstrated the environmental trade-offs between decreased food services and increased food consumption at home, resulting in diverse trends for food-related life cycle environmental impacts.
Journal Article
Study on the effect of digital economy on high-quality economic development in China
At present, the digital economy, which takes information technology and data as the key elements, is booming and has become an important force in promoting the economic growth of various countries. In order to explore the current dynamic trend of China’s digital economy development and the impact of the digital economy on the high-quality economic development, this paper measures the digital economic development index of 30 cities in China from the three dimensions of digital infrastructure, digital industry, and digital integration, uses panel data of 30 cities in China from 2015 to 2019 to construct an econometric model for empirical analysis, and verifies the mediating effect of technological progress between the digital economy and high-quality economic development. The results show that (1) The development level of China’s digital economy is increasing year by year, that the growth of digital infrastructure is obvious, and that the development of the digital industry is relatively slow. (2) Digital infrastructure, digital industry and digital integration all have significant positive effects on regional total factor productivity, and the influence coefficients are 0.2452, 0.0773 and 0.3458 respectively. (3) Regarding the transmission mechanism from the digital economy to the high-quality economic development, the study finds that the mediating effect of technological progress is 0.1527, of which the mediating effect of technological progress in the eastern, northeast, central and western regions is 1.70%, 9.25%, 28.89% and 21.22% respectively. (4) From the perspective of spatial distribution, the development level of the digital economy in the eastern region is much higher than that in other non-eastern regions, and the development of digital economy in the eastern region has a higher marginal contribution rate to the improvement of the total factor productivity. This study can provide a theoretical basis and practical support for the government to formulate policies for the development of the digital economy.
Journal Article
Temperature Dependence of Spin and Charge Orders in the Doped Two-Dimensional Hubbard Model
Competing and intertwined orders including inhomogeneous patterns of spin and charge are observed in many correlated electron materials, such as high-temperature superconductors. Introducing a new development of the constrained-path auxiliary-field quantum Monte Carlo method, we study the interplay between thermal and quantum fluctuations in the two-dimensional Hubbard model. We obtain an accurate and systematic characterization of the evolution of the spin and charge correlations as a function of temperatureTand how it connects to the ground state, at three representative hole doping levelsδ=1/5,1/8, and1/10. We find increasing short-range commensurate antiferromagnetic correlations asTis lowered. As the correlation length grows sufficiently large, a modulated spin-density wave (SDW) appears. Atδ=1/5andU/t=6, the SDW saturates and remains short-ranged asT→0. In contrast, atδ=1/8,1/10andU/t=8, this evolves into a ground-state stripe phase. We study the relation between spin and charge orders and find that formation of charge order appears to be driven by that of the spin order. We identify a finite-temperature phase transition below which charge ordering sets in and discuss the implications of our results for the nature of this transition.
Journal Article
Monkeyflowers (Mimulus)
Monkeyflowers (Mimulus) have long been recognized as a classic ecological and evolutionary model system. However, only recently has it been realized that this system also holds great promise for studying the developmental genetics and evo-devo of important plant traits that are not found in well-established model systems such as Arabidopsis. Here, I review recent progress in four different areas of plant research enabled by this new model, including transcriptional regulation of carotenoid biosynthesis, formation of periodic pigmentation patterns, developmental genetics of corolla tube formation and elaboration, and the molecular basis of floral trait divergence underlying pollinator shift. These examples suggest that Mimulus offers ample opportunities to make exciting discoveries in plant development and evolution.
Journal Article