SUMMARY
Developing seed depends on sugar supply for its growth and yield formation. Maize (Zea mays L.) produces the largest grains among cereals. However, there is a lack of holistic understanding ...of the transcriptional landscape of genes controlling sucrose transport to, and utilization within, maize grains. By performing in‐depth data mining of spatio‐temporal transcriptomes coupled with histological and heterologous functional analyses, we identified transporter genes specifically expressed in the maternal–filial interface, including (i) ZmSWEET11/13b in the placento‐chalazal zone, where sucrose is exported into the apoplasmic space, and (ii) ZmSTP3, ZmSWEET3a/4c (monosaccharide transporters), ZmSUT1, and ZmSWEET11/13a (sucrose transporters) in the basal endosperm transfer cells for retrieval of apoplasmic sucrose or hexoses after hydrolysis by extracellular invertase. In the embryo and its surrounding regions, an embryo‐localized ZmSUT4 and a cohort of ZmSWEETs were specifically expressed. Interestingly, drought repressed those ZmSWEETs likely exporting sucrose but enhanced the expression of most transporter genes for uptake of apoplasmic sugars. Importantly, this drought‐induced fluctuation in gene expression was largely attenuated by an increased C supply via controlled pollination, indicating that the altered gene expression is conditioned by C availability. Based on the analyses above, we proposed a holistic model on the spatio‐temporal expression of genes that likely govern sugar transport and utilization across maize maternal and endosperm and embryo tissues during the critical stage of grain set. Collectively, the findings represent an advancement towards a holistic understanding of the transcriptional landscape underlying post‐phloem sugar transport in maize grain and indicate that the drought‐induced changes in gene expression are attributable to low C status.
Significance Statement
Although maize (Zea mays L.) produces the largest grain among cereals through a small ‘gateway’ for assimilates, indicating a strong sink capacity, there is a lack of holistic understanding of the molecular basis underlying sugar import into the grains. Here, we uncovered a cohort of key genes controlling sugar delivery to the endosperm and embryo and further found that drought repressed those genes exporting sucrose into the apoplasmic space but enhanced those genes involved in uptake of sugars by the filial tissues.
This paper employs metafrontier malmquist luenberger index and a spatial Durbin model to investigate the influence of both local and civil environmental regulation and its spatial spillover effect on ...green total factor productivity in 273 cities of China in 2003–2013. According to city political attribute and regional differences, this article divides the sample city into six categories. The results show that effect of local environmental regulation on green total factor productivity is significantly positive in high political attribute cities (A1 and A2 zone), but negative effects in lower political attribute cities (B2 and B3 zone). Moreover, the ‘race to the top’ results in significantly positive spatial spillover effects from local environmental regulation on green total factor productivity in high political attribute cities (A1 and A2 zone), while the ‘race to the bottom’ causes significantly negative spatial spillover effects in lower political attribute cities (B2 and B3 zone). As for civil environmental regulation, it has positive direct and indirect effects in promoting green total factor productivity. We further find that environmental regulation inhibits the original technological innovation of enterprises, which suggests that government should reduce market intervention, improve enterprise flexibility of market change, and promote enterprises to carry out the original technological innovation. Thus, the government and citizen should make targeted pollution-reduction policies for the green total factor productivity increase.
Colorectal cancer (CRC) is a common malignant tumor that affects people worldwide. Metagenomic analyses have shown an enrichment of Fusobacterium nucleatum (F. nucleatum) in colorectal carcinoma ...tissue; many studies have indicated that F. nucleatum is closely related to the colorectal carcinogenesis. In this review, we provide the latest information to reveal the related molecular mechanisms. The known virulence factors of F. nucleatum promote adhesion to intestinal epithelial cells via FadA and Fap2. Besides, Fap2 also binds to immune cells causing immunosuppression. Furthermore, F. nucleatum recruits tumor-infiltrating immune cells, thus yielding a pro-inflammatory microenvironment, which promotes colorectal neoplasia progression. F. nucleatum was also found to potentiate CRC development through toll-like receptor 2 (TLR2)/toll-like receptor 4 (TLR4) signaling and microRNA (miRNA)-21 expression. In addition, F. nucleatum increases CRC recurrence along with chemoresistance by mediating a molecular network of miRNA-18a*, miRNA-4802, and autophagy components. Moreover, viable F. nucleatum was detected in mouse xenografts of human primary colorectal adenocarcinomas through successive passages. These findings indicated that an increased number of F. nucleatum in the tissues is a biomarker for the diagnosis and prognosis of CRC, and the underlying molecular mechanism can probably provide a potential intervention treatment strategy for patients with F. nucleatum-associated CRC.
Overproduction of oxidants (reactive oxygen species and reactive nitrogen species) in the human body is responsible for the pathogenesis of some diseases. The scavenging of these oxidants is thought ...to be an effective measure to depress the level of oxidative stress of organisms. It has been reported that intake of vegetables and fruits is inversely associated with the risk of many chronic diseases, and antioxidant phytochemicals in vegetables and fruits are considered to be responsible for these health benefits. Antioxidant phytochemicals can be found in many foods and medicinal plants, and play an important role in the prevention and treatment of chronic diseases caused by oxidative stress. They often possess strong antioxidant and free radical scavenging abilities, as well as anti-inflammatory action, which are also the basis of other bioactivities and health benefits, such as anticancer, anti-aging, and protective action for cardiovascular diseases, diabetes mellitus, obesity and neurodegenerative diseases. This review summarizes recent progress on the health benefits of antioxidant phytochemicals, and discusses their potential mechanisms in the prevention and treatment of chronic diseases.
Flat Boron: A New Cousin of Graphene Xie, Sheng‐Yi; Wang, Yeliang; Li, Xian‐Bin
Advanced materials (Weinheim),
09/2019, Volume:
31, Issue:
36
Journal Article
Peer reviewed
The mechanical exfoliation of graphene from graphite provides the cornerstone for the synthesis of other 2D materials with layered bulk structures, such as hexagonal boron nitride, transition metal ...dichalcogenides, black phosphorus, and so on. However, the experimental production of 2D flat boron is challenging because bulk boron has very complex spatial structures and a rich variety of chemical properties. Therefore, the realization of 2D flat boron marks a milestone for the synthesis of 2D materials without layered bulk structures. The historical efforts in this field, particularly the most recent experimental progress, such as the growth of 2D flat boron on a metal substrate by chemical vapor deposition and molecular beam epitaxy, or liquid exfoliation from bulk boron, are described.
The successful synthesis of borophene on metal substrates marks a milestone for the synthesis of 2D materials without layered bulk structures, just as graphene is the cornerstone for synthesizing 2D materials with layered bulk structures. The exotic properties and wide applications of borophene make it a new cousin of graphene in the family of 2D materials.
Rate control is a useful tool for video coding, especially in real-time communication applications. Most of existing rate control algorithms are based on the R - Q model, which characterizes the ...relationship between bitrate R and quantization Q, under the assumption that Q is the critical factor on rate control. However, with the video coding schemes becoming more and more flexible, it is very difficult to accurately model the R - Q relationship. In fact, we find that there exists a more robust correspondence between R and the Lagrange multiplier λ. Therefore, in this paper, we propose a novel λ-domain rate control algorithm based on the R - λ model, and implement it in the newest video coding standard high efficiency video coding (HEVC). Experimental results show that the proposed λ-domain rate control can achieve the target bitrates more accurately than the original rate control algorithm in the HEVC reference software as well as obtain significant R-D performance gain. Thanks to the high accurate rate control algorithm, hierarchical bit allocation can be enabled in the implemented video coding scheme, which can bring additional R-D performance gain. Experimental results demonstrate that the proposed λ-domain rate control algorithm is effective for HEVC, which outperforms the R - Q model based rate control in HM-8.0 (HEVC reference software) by 0.55 dB on average and up to 1.81 dB for low delay coding structure, and 1.08 dB on average and up to 3.77 dB for random access coding structure. The proposed λ-domain rate control algorithm has already been adopted by Joint Collaborative Team on Video Coding and integrated into the HEVC reference software.
Natural antioxidants are widely distributed in food and medicinal plants. These natural antioxidants, especially polyphenols and carotenoids, exhibit a wide range of biological effects, including ...anti-inflammatory, anti-aging, anti-atherosclerosis and anticancer. The effective extraction and proper assessment of antioxidants from food and medicinal plants are crucial to explore the potential antioxidant sources and promote the application in functional foods, pharmaceuticals and food additives. The present paper provides comprehensive information on the green extraction technologies of natural antioxidants, assessment of antioxidant activity at chemical and cellular based levels and their main resources from food and medicinal plants.
Supramolecular hydrogels involved macrocycles have been explored widely in recent years, but it remains challenging to develop hydrogel based on solitary macrocycle with super gelation capability. ...Here, the construction of lantern3
arene-based hydrogel with low critical gelation concentration (0.05 wt%), which can be used for efficient oil-water separation, is reported. The lantern3
arenes self-assemble into hydrogen-bonded organic nanoribbons, which intertwine into entangled fibers to form hydrogel. This hydrogel which exhibits reversible pH-responsiveness characteristics can be coated on stainless-steel mesh by in situ sol-gel transformation. The resultant mesh exhibits excellent oil-water separation efficiency (>99%) and flux (>6 × 10
L m
h
). This lantern3
arene-based hydrogel not only sheds additional light on the gelation mechanisms for supramolecular hydrogels, but also extends the application of macrocycle-based hydrogels as functional interfacial materials.
Tea is widely consumed all over the world. Generally, tea is divided into six categories: White, green, yellow, oolong, black, and dark teas, based on the fermentation degree. Tea contains abundant ...phytochemicals, such as polyphenols, pigments, polysaccharides, alkaloids, free amino acids, and saponins. However, the bioavailability of tea phytochemicals is relatively low. Thus, some novel technologies like nanotechnology have been developed to improve the bioavailability of tea bioactive components and consequently enhance the bioactivity. So far, many studies have demonstrated that tea shows various health functions, such as antioxidant, anti-inflammatory, immuno-regulatory, anticancer, cardiovascular-protective, anti-diabetic, anti-obesity, and hepato-protective effects. Moreover, it is also considered that drinking tea is safe to humans, since reports about the severe adverse effects of tea consumption are rare. In order to provide a better understanding of tea and its health potential, this review summarizes and discusses recent literature on the bioactive components, bioavailability, health functions, and safety issues of tea, with special attention paid to the related molecular mechanisms of tea health functions.
Histogram shifting (HS) is a useful technique of reversible data hiding (RDH). With HS-based RDH, high capacity and low distortion can be achieved efficiently. In this paper, we revisit the HS ...technique and present a general framework to construct HS-based RDH. By the proposed framework, one can get a RDH algorithm by simply designing the so-called shifting and embedding functions. Moreover, by taking specific shifting and embedding functions, we show that several RDH algorithms reported in the literature are special cases of this general construction. In addition, two novel and efficient RDH algorithms are also introduced to further demonstrate the universality and applicability of our framework. It is expected that more efficient RDH algorithms can be devised according to the proposed framework by carefully designing the shifting and embedding functions.
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