Hexose transporter CsSWEET7a in cucumber mediates phloem unloading in companion cells for fruit development

In the fleshy fruit of cucumbers (Cucumis sativus L.), the phloem flow is unloaded via an apoplasmic pathway, which requires protein carriers to export sugars derived from stachyose and raffinose into the apoplasm. However, transporter(s) involved in this process remain unidentified. Here, we report that a hexose transporter, CsSWEET7a (Sugar Will Eventually be Exported Transporter 7a), was highly expressed in cucumber sink tissues and localized to the plasma membrane in companion cells of the phloem. Its expression level increased gradually during fruit development. Down-regulation of CsSWEET7a by RNA interference (RNAi) resulted in smaller fruit size along with reduced soluble sugar levels and reduced allocation of ¹⁴C-labelled carbon to sink tissues. CsSWEET7a overexpression lines showed an opposite phenotype. Interestingly, genes encoding alkaline α-galactosidase (AGA) and sucrose synthase (SUS) were also differentially regulated in CsSWEET7a transgenic lines. Immunohistochemical analysis demonstrated that CsAGA2 co-localized with CsSWEET7a in companion cells, indicating cooperation between AGA and CsSWEET7a in fruit phloem unloading. Our findings indicated that CsSWEET7a is involved in sugar phloem unloading in cucumber fruit by removing hexoses from companion cells to the apoplasmic space to stimulate the raffinose family of oligosaccharides (RFOs) metabolism so that additional sugars can be unloaded to promote fruit growth. This study also provides a possible avenue towards improving fruit production in cucumber.

Transporter CsSWEET7a removes hexose from companion cells to the apoplasmic space to stimulate fruit phloem unloading so that additional sugars can be unloaded to promote fruit growth.     

Tryptic Stability and Antimicrobial Activity of the Derivatives of Polybia-CP with Fine-Tuning Modification in the Side Chain of Lysine

International Journal of Peptide Research and Therapeutics - Antimicrobial peptides (AMPs) were believed to be a class of promising antimicrobials to combat the increasing resistant microbes....     

The Expression Patterns of Nogo-A and NgR in the Neonatal Rat Visual Nervous System

Previous studies have shown that Nogo-NgR system plays multiple roles in controlling axonal regeneration and neuronal plasticity. However, the investigation on the distributions of Nogo and NgR was limited to restricted areas or special ages, and their expression patterns in the neonatal visual nervous system is still unknown. Frozen sections were made from eyeballs and brains of three neonatal rats, and expression of Nogo and NgR proteins were examined by immunofluorescence under a laser confocal microscopy. Nogo and NgR were observed to express in the cell bodies of retina, lateral geniculate bodies and visual cortex of the neonatal rats. Our results provide evidences that the Nogo-NgR system may play an active role in the plasticity of neonatal visual system. Y. Xiaolei, Y. Rongdi and J. Shuxing contributed equally to this work.     

基于社区营造的城市公共空间微更新探讨

随着城市建设进入由增量转向存量的阶段，渐进式的微更新成为城市更新和改造的主要模式。以公众参与为基础、微小社区空间和公共空间设施为改造对象的局部更新方式，成为激发城市活力、提升建成城市公共空间品质的新方式。主要以北京、上海为例，对城市微更新的发展背景加以分析，对微更新背景下的城市公共空间的多重含义进行阐述，在此基础上总提出基于社区营造的城市公共空间的微更新途径，分别是边缘空间的整合和触媒方式的选择、场地历史文脉原真性的挖掘和社区居民社会生活方式的保护、多方协作的开放沟通平台和责任规划师制度的建立。     

Unnatural flooding alters the functional diversity of riparian vegetation of the Three Gorges Reservoir

1. The response of riparian vegetation to flow regulation has been a research focus for decades. Several studies have shed light on the effects of flow stabilisation on riparian woody species, but other life forms exposed to intensified inundation have been overlooked. Furthermore, studies from a functional perspective are scarce.
2. We evaluated the functional response of riparian vegetation along the shores of the Three Gorges Reservoir on the Yangtze River in China to unnaturally long annual flooding (>7 months) after the first year of filling. We aimed to answer the following: (1) can we derive well-defined flow-response guilds from the riparian zones of the Yangtze River? and (2) which plant traits and guilds are favoured or disfavoured by the unnaturally long flooding environment?
3. Woody and herbaceous species were inventoried in 12 reaches along the shorelines of the Three Gorges Reservoir and another 12 reaches along the free-flowing Yangtze River. We performed a cluster analysis to derive riparian guilds using abundance data (projective coverage) from 40 riparian plant species and 13 responsive traits. Structural composition and functional diversity of the unnaturally and naturally flooded riparian vegetation were compared.
4. Unnaturally long flooding substantially reduced species richness, but it did not change the riparian vegetation cover. This novel flooding reduced functional diversity, mostly owing to the loss of stress-tolerant woody species and competitive perennial herbs. However, competitive annual herbs and flood-tolerant riparian herbs, as the most abundant functional guilds, were favoured even under such long-term hypoxic conditions.
5. These guilds under regulation revealed a high functional resilience to prolonged flooding along the upstream reaches of the Yangtze River. Flooding tolerance and the capacity to synchronise germination and growth with short-exposure periods underlie the plant species changes. Our findings are useful for anticipating the effects of long-lasting inundation on riparian areas triggered by flow regulation or warmer climates. The functional perspective lends confidence that our conclusions can be generalised to other geographical regions despite not sharing the same species pool. Finally, the plant species that showed a high flooding tolerance should be considered for the restoration of riparian areas affected by the Three Gorges Reservoir.