Capsular polysaccharides facilitate enhanced iron acquisition by the colonial cyanobacterium Microcystis sp. isolated from a freshwater lake

Microcystis sp., especially in its colonial form, is a common dominant species during cyanobacterial blooms in many iron‐deficient water bodies. It is still not entirely clear, however, how the colonial forms of Microcystis acclimate to iron‐deficient habitats, and the responses of unicellular and colonial forms to iron‐replete and iron‐deficient conditions were examined here. Growth rates and levels of photosynthetic pigments declined to a greater extent in cultures of unicellular Microcystis than in cultures of the colonial form in response to decreasing iron concentrations, resulting in the impaired photosynthetic performance of unicellular Microcystis as compared to colonial forms as measured by variable fluorescence and photosynthetic oxygen evolution. These results indicate that the light‐harvesting ability and photosynthetic capacity of colonial Microcystis was less affected by iron deficiency than the unicellular form. The carotenoid contents and nonphotochemical quenching of colonial Microcystis were less reduced than those of the unicellular form under decreasing iron concentrations, indicating that the colonial morphology enhanced photoprotection and acclimation to iron‐deficient conditions. Furthermore, large amounts of iron were detected in the capsular polysaccharides (CPS) of the colonies, and more iron was found to be attached to the colonial Microcystis CPS under decreasing iron conditions as compared to unicellular cultures. These results demonstrated that colonial Microcystis can acclimate to iron deficiencies better than the unicellular form, and that CPS plays an important role in their acclimation advantage in iron‐deficient waters.     

Up-Regulation of microRNA-183 Promotes Cell Proliferation and Invasion in Glioma By Directly Targeting NEFL

Glioblastoma multiforme (GBM) is the most common and lethal type of primary malignant brain tumor. In recent years, increasing reports suggest that discovery of microRNAs (miRNAs) might provide a novel therapeutical target for human cancers, including GBM. The expression and roles of microRNA-183 (miR-183) has been explored in several types of human cancers, including in GBM, and plays important roles in tumor initiation and progression. However, its biological functions in GBM remain largely unknown. In this study, we demonstrated that miR-183 was significantly up-regulated in astrocytoma tissues and glioblastoma cell lines. Introduction of miR-183 mimics into U251 cells could promoted, while its antisense oligos inhibited cell proliferation and invasion. Moreover, we identified neurofilament light polypeptide (NEFL) as a novel target gene of miR-183. The expression levels of NEFL are inversely correlated with that of miR-183 in human astrocytoma clinical specimens. In addition, NEFL-siRNA could significantly attenuate the inhibitory effects of knockdown miR-183 on the proliferation and invasion of U251 cells via mTOR signaling pathway. Overall, This study revealed that miR-183 promotes glioma cell proliferation by targeting NEFL, and also demonstrated that miR-183 could be a potential target for GBM treatment.     

Exogenous Ca2+ alleviates waterlogging-caused damages to pepper

Ca²⁺ has been considered as a necessary ion for alleviation of stress-induced damages in plants. We investigated effects of exogenous Ca²⁺ on waterlogging-induced damage to pepper and its underlying mechanisms. Pepper seedlings under stress were treated by spraying of 10 mM CaCl₂. Applying exogenous Ca²⁺ increased the biomass of pepper leaves and roots, improved photosynthetic characteristics, membrane permeability, root activity, osmotic substance contents, antioxidant enzyme and alcohol dehydrogenase activities, while it reduced lactate dehydrogenase activity. It maintained hydroxide radical contents and activities of malate dehydrogenase and succinate dehydrogenase relatively high. Our results suggested that applying exogenous Ca²⁺ could regulate osmotic substance contents, antioxidant system activity, root respiration, and metabolism, and subsequently alleviate waterlogging-induced damages to pepper plants.     

Asymmetric exponential amplification reaction on a toehold/biotin featured template: an ultrasensitive and specific strategy for isothermal microRNAs analysis

The sensitive and specific analysis of microRNAs (miRNAs) without using a thermal cycler instrument is significant and would greatly facilitate biological research and disease diagnostics. Although exponential amplification reaction (EXPAR) is the most attractive strategy for the isothermal analysis of miRNAs, its intrinsic limitations of detection efficiency and inevitable non-specific amplification critically restrict its use in analytical sensitivity and specificity. Here, we present a novel asymmetric EXPAR based on a new biotin/toehold featured template. A biotin tag was used to reduce the melting temperature of the primer/template duplex at the 5′ terminus of the template, and a toehold exchange structure acted as a filter to suppress the non-specific trigger of EXPAR. The asymmetric EXPAR exhibited great improvements in amplification efficiency and specificity as well as a dramatic extension of dynamic range. The limit of detection for the let-7a analysis was decreased to 6.02 copies (0.01 zmol), and the dynamic range was extended to 10 orders of magnitude. The strategy enabled the sensitive and accurate analysis of let-7a miRNA in human cancer tissues with clearly better precision than both standard EXPAR and RT-qPCR. Asymmetric EXPAR is expected to have an important impact on the development of simple and rapid molecular diagnostic applications for short oligonucleotides.     

Development of near-isogenic lines with different alleles of Piz locus and analysis of their breeding effect under Yangdao 6 background

Rice blast is one of the most destructive diseases of rice. The most effective way of managing this disease is to develop resistant cultivars by introducing resistance genes into elite rice recipients. In this study, the near-isogenic lines (NILs) of six resistance alleles of the Piz locus (Pizt, Pi2, Pigm, Pi40, Pi9 and Piz) were constructed with Yangdao 6 as genetic background. Seedling inoculation tests showed that most of the NILs, namely NIL-Pi2, NIL-Pigm, NIL-Pi9, NIL-Pizt and NIL-Pi40, exhibited good resistance to blast with resistance frequencies (RFs) of over 82.50 %, execpt NIL-Piz which showed lower resistance with a RF of only 36.13 %. Furthermore, the improved-resistance NILs exhibited high similarity of their resistance spectra, with overlapping degrees of resistance spectrum (OD) of more than 75.83 %. However, the RF of panicle blast for all NILs decreased significantly compared with seedling blast in an artificial inoculation test. Although NIL-Pigm showed a higher panicle blast RF of 80 %, other NILs with outstanding performance in seedling blast resistance, namely NIL-Pizt, NIL-Pi2, NIL-Pi9 and NIL-Pi40, exhibited middle or low RFs of panicle blast with values from 56.67 to 33.30 %. Natural induction in a disease nursery showed a consistent trend in artificial inoculation results at seedling and heading stages. While NIL-Pigm was found to exhibit good resistance to leaf blast and panicle blast, NIL-Pi9 and NIL-Pizt were further demonstrated to show excellent resistance in Suichuan, Jiangxi province and Enshi, Hubei province, respectively, because of the race–region specificity. Agronomic traits of NILs were also investigated in order to evaluate the linkage drag effect of different alleles of the Piz locus. The resistance effects of the different alleles of the Piz locus under identical genetic background against seedling blast and panicle blast was first reported in this study, and the above results are expected to provide a theoretical support for the rational utilization of broad-spectrum resistance genes in breeding practice.