[Potential of Arbuscular Mycorrhizal Fungi, Biochar, and Combined Amendment on Sandy Soil Improvement Driven by Microbial Community].

Sandy soils are considered as a significant transition phase to desertification. The effective recovery of sandy soils is of great significance to mitigate the desertification process. Some studies have shown that arbuscular mycorrhizal (AM) fungi and biochar improved the sandy soil, but there have been very few studies regarding the combined effects of AM fungi and biochar amendments on sandy soil improvement. Additionally, the roles of the bacterial and fungal community during the process of sandy soil improvement remain unclear. A greenhouse pot experiment with four treatments, including a control (CK, no amendment), single AM fungi-assisted amendment (RI), single biochar amendment (BC), and combined amendment (BC_RI, biochar plus AM fungi), was set up. This study investigated the effects of different amendment methods on the Nitrariasi birica mycorrhizal colonization, biomass, nutrient (N, P, K, Ca, and Mg) content, soil organic carbon, soil nutrient (TN, TP, and TK) content, and soil water-stable aggregate composition. High throughput sequencing technology was used to investigate the roles of the bacterial and fungal communities during the process of sandy soil improvement. Combined with multiple analysis methods, the improvement mechanisms of different amendment methods were explored. The aim was to provide basic data and scientific basics for reasonably and effectively improving sandy soils. The results indicated that a significant mycorrhiza colonization was observed in the inoculation (RI and BC_RI) treatments, but there was no substantial difference in the mycorrhiza colonization with the RI and BC_RI. Compared with the CK, the shoot biomass and shoot element (N, K, Ca, and Mg) contents were significantly increased in the RI, and the shoot element (N, P, K, Ca, and Mg) contents were significantly increased in the BC and BC_RI; compared with the RI and BC, the root biomass and the root element (P, K, Ca, and Mg) contents were significantly increased in the BC_RI. Compared with the CK, the soil organic carbon contents were significantly increased in the BC and BC_RI, the soil TN contents were significantly increased by 152.54%, and the soil TP and TK contents were significantly decreased by 12.5% and 18.8%, respectively. The proportion of soil aggregates with particle sizes of 0.25-0.05 mm was the highest in each treatment, and the large particle size (>0.25 mm) soil aggregate was significantly increased in the BC_RI. Compared with the CK, the Sobs and Shannon indices of the bacterial/fungal community were significantly decreased in the RI and BC_RI. There was a difference in the microbial community compositions and abundance in the various treatments. The results of the RDA and network analysis were as follows:the effects of AM fungi, biochar, and combined amendment on the soil environment and microbial community structure were significant; in the different amendment treatments, the relationship of the microbial molecular ecological network was significantly changed, and the composition of the core species varied; compared with the RI, there was a higher network connection degree and a richer core species composition in the BC and BC_RI; moreover, the essential role of Rhizophagus intraradices was weaken and the core roles of the other microorganisms (especially bacterial species) were enhanced under the combined effects of biochar and AM fungi. The SEM results demonstrated that the application of AM fungi and biochar could directly affect the bacteria/fungi community structure, and further affect the plant growth and soil properties. The differences in the microbial community structure (especially the change in the microbial interaction) were the key driving factors that led to the difference in the soil improvement effectiveness. In summary, the effects of the different amendment methods on the improvement effectiveness of sandy soils varied. The microbial community played key roles in the process of sandy soil improvement, and there were potential advantages and applications in accelerating the ecological restoration of sandy soils under the combined AM fungi and biochar amendment.

MicroRNA-34a promotes MICB expression in hepatocytes.

MicroRNA-34a (miR-34a) behaves as a tumor suppressor by decreasing the expression of oncogenes involved in multiple carcinogenic pathways. Intravenous delivery of miR-34a mimics has been investigated in clinical trials as a potential treatment for advanced cancers; however, the effect of miR-34a on cancer immune surveillance is controversial. In the current study, we found that miR-34a plays a dual role in the regulation of major histocompatibility complex class I-related sequence B (MICB) protein, a ligand of the NKG2D receptor. MiR-34a could both induce and reduce MICB expression by upregulating ataxia telangiectasia and Rad3-related (ATR) protein kinase and downregulating the transcription factor E2F1, respectively. The net effect of miR-34a on MICB expression depended on endogenous E2F1 levels. Overexpression of miR-34a promoted MICB expression in hepatocytes and hepatocellular carcinoma (HCC) cells that have low E2F1 levels but not in HCC cells that have high E2F1 levels. In HCC patients, the expression of miR-34a and MICB showed positive correlation in paratumor liver tissues, which have low E2F1 levels, but not in HCC tissues, which have high E2F1 levels. We showed that miR-34a overexpression in non-transformed liver cells enhanced cytolysis and interferon-γ production by NK-92MI cells. Furthermore, higher miR-34a expression in tumor and paratumor tissues was associated with positive and negative outcomes, respectively, in HCC patients. Our findings suggest that miR-34a induces MICB expression in paratumor liver tissues, which may cause liver damage and serious cytokine release syndrome, thus disclosing potential side effects of systemic administration of miR-34a in anticancer therapy.

[Sequential selection of representative color samples for spectral reflectance reconstruction].

Spectral reflectance reconstruction, also referred to as spectral characterization, aims to recover accurate spectral reflectance of object surface by employing standard color charts. As there are always a large number of color samples on a color chart, spectral characterization becomes a time-consuming process for practical application. Some methods have been presented to selected representative color samples based on the redundancy of the colors on a chart. However, these methods only consider the distribution of spectral reflectance, and thus the selected colors may not be optimal for a specific imaging system. To deal with this problem, the present paper proposes a sequential method for the selection of most representative colors, which consists of two steps. In the first step, a part of representative colors are selected according to the minimization of mean spectral root-mean-square error, by assuming a virtual imaging system. The spectral responsivity of the real imaging system is then calculated based on these selected samples. In the second step, additional representative colors are selected based on the characteristics of the real imaging system. Two quite different systems, i. e. , an 11-channel narrowband multispectral imaging system and a 3-channel broadband color scanner, were used in the experiment. It was shown that the proposed method significantly outperforms the previous method in terms of both spectral and colorimetric accuracy.