An Efficient Marker Gene Excision Strategy Based on CRISPR/Cas9-Mediated Homology-Directed Repair in Rice

In order to separate transformed cells from non-transformed cells, antibiotic selectable marker genes are usually utilized in genetic transformation. After obtaining transgenic plants, it is often necessary to remove the marker gene from the plant genome in order to avoid regulatory issues. However, many marker-free systems are time-consuming and labor-intensive. Homology-directed repair (HDR) is a process of homologous recombination using homologous arms for efficient and precise repair of DNA double-strand breaks (DSBs). The clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein-9 (Cas9) system is a powerful genome editing tool that can efficiently cause DSBs. Here, we isolated a rice promoter (Pssi) of a gene that highly expressed in stem, shoot tip and inflorescence, and established a high-efficiency sequence-excision strategy by using this Pssi to drive CRISPR/Cas9-mediated HDR for marker free (PssiCHMF). In our study, PssiCHMF-induced marker gene deletion was detected in 73.3% of T₀ plants and 83.2% of T₁ plants. A high proportion (55.6%) of homozygous marker-excised plants were obtained in T₁ progeny. The recombinant GUS reporter-aided analysis and its sequencing of the recombinant products showed precise deletion and repair mediated by the PssiCHMF method. In conclusion, our CRISPR/Cas9-mediated HDR auto-excision method provides a time-saving and efficient strategy for removing the marker genes from transgenic plants.     

反舰导弹多前置射击方式研究

为了实现无航路规划反舰导弹从不同角度进入目标,提出了半前置点和反舰导弹多前置射击的概念.在分析反舰导弹前置点和现在点射击原理的基础上,建立了多前置点射击方程和多前置射击的目标捕捉模型.仿真显示在一定条件下多前置射击是可行的,而且能实现齐射的反舰导弹从不同的方向进入目标,有利于无航路规划能力反舰导弹的突防.     

自组织映射（S0M）型神经网络的实现

文章讨论了应用于自组织映射型神经网络的训练算法，该算法通过计算获胜神经元来找到最接近输入模式的节点．然后通过对网络连接权值的自组织，训练一个自组织竞争的神经网络，该网络通过一组输入数据可自行训练形成一个神经网络模型，     

苦笋壳提取物不同极性相抗氧化与降血糖活性研究

研究苦笋壳不同提取相的抗氧化作用和对α-葡萄糖苷酶和α-淀粉酶的活性抑制作用。以70%(体积分数)乙醇和水分别对苦笋壳进行提取,并测定提取物中的黄酮、总酚及总糖含量。以ABTS阳离子自由基、DPPH自由基、·OH清除能力、铁离子抗氧化能力(ferric reducing ability of plasma, FRAP)等方法评价其抗氧化活性,测定乙酸乙酯、正丁醇、石油醚3种萃取相对α-葡萄糖苷酶和α-淀粉酶的抑制活性。结果表明,水提方式总糖含量为(97.3±0.28)%,高于醇提方式。总酚和黄酮含量在醇提相中较高,分别是(28.53±1.67)%和(27.22±2.02)%。从对α-葡萄糖苷酶抑制活性上看,醇提相大于水提相。醇提方式下抗氧化活性：乙酸乙酯相>正丁醇相>石油醚相,乙酸乙酯相对·OH清除能力可达(67.32±1.57)%,乙酸乙酯相对α-葡萄糖苷酶和α-淀粉酶的抑制活性最强,IC₅₀值分别是(0.158±0.003)、(0.104±0.006)mg/mL,酶抑制动力学结果表明苦笋壳乙酸乙酯相对α-葡萄糖苷酶抑制类型为竞争性抑制类型,对α-淀...     

Physical,thermal and structural properties of rice starch as affected by the addition of bamboo shoot shell fibres

The effects of different bamboo shoot shell fibre (BSSF) content (1, 2, 5 and 10%, w/w) on the physical, thermal and structural properties of rice starch were investigated. BSSFs significantly affected the properties of rice starch by competitive water absorption and hydrogen bonding. With increased BSSF content, the breakdown value and pasting temperature of rice starch were increased, whereas the peak viscosity, final viscosity and setback value were decreased. Thermodynamic results showed that the gelatinisation temperature and gelatinisation enthalpy of rice starch were significantly increased by the 5% and 10% BSSFs. Furthermore, BSSFs interconnected with amylose through hydrogen bonds to restrain gel-structure formation, thereby resulting in low storage modulus and loss modulus of rice starch paste. A loose structure of rice starch supplemented with 10% BSSFs was clearly visible, exhibiting the minimum values of hardness (32.12 ± 4.47 g) and adhesiveness (64.70 ± 17.32 g). Moreover, BSSFs increased the amount of short-range ordered structures but had no effect on the crystal type of rice starch. These results may contribute to the manufacture and development of fibre-enriched starchy products.     

Genome-Wide Identification of Barley Long Noncoding RNAs and Analysis of Their Regulatory Interactions during Shoot and Grain Development

Long noncoding RNAs (lncRNAs) are a class of RNA molecules with gene regulatory functions in plant development and the stress response. Although the number of lncRNAs identified in plants is rapidly increasing, very little is known about their role in barley development. In this study, we performed global identification of barley lncRNAs based on 53 RNAseq libraries derived from nine different barley tissues and organs. In total, 17,250 lncRNAs derived from 10,883 loci were identified, including 8954 novel lncRNAs. Differential expression of lncRNAs was observed in the developing shoot apices and grains, the two organs that have a direct influence on the final yield. The regulatory interaction of differentially expressed lncRNAs with the potential target genes was evaluated. We identified 176 cis-acting lncRNAs in shoot apices and 424 in grains, while the number of trans-acting lncRNAs in these organs was 1736 and 540, respectively. The potential target protein-coding genes were identified, and their biological function was annotated using MapMan ontology. This is the first insight into the roles of lncRNAs in barley development on the genome-wide scale, and our results provide a solid background for future functional studies.     

不同解冻方式对速冻方竹笋品质的影响

为了探究不同解冻方式对速冻方竹笋品质的影响，采用微波解冻、超声波解冻、自然解冻、20 ℃水浴解冻和50 ℃水浴解冻5 种方式对方竹笋进行处理，测定了解冻后竹笋的汁液流失、硬度、色泽、基本成分、过氧化物酶（peroxidase，POD）活力、多酚氧化酶（polyphenol oxidase，PPO）活力和苯丙氨酸解氨酶（phenylalnine ammonialyase，PAL）活力以及微观结构的变化。结果表明：5 种解冻方式的解冻时间差异显著（P＜0.05），微波解冻时间比自然解冻缩短了97%；解冻后的汁液流失率由高到低依次为：自然解冻＞50 ℃水浴解冻＞微波解冻＞20 ℃水浴解冻＞超声波解冻，解冻后汁液流失较高的竹笋硬度较小。超声波解冻对竹笋的色泽影响最小，?E为1.72，且营养品质保持得较好，VC含量是自然解冻组的1.35 倍。不同解冻方式竹笋的PPO活力无显著差异（P＞0.05），超声解冻竹笋的POD和PAL活力最低。通过扫描电子显微镜观察到自然解冻对方竹笋组织结构的破坏最大，超声波解冻的方竹笋组织结构保持得较好。本研究可为速冻方竹笋适宜解冻方法的选择及工业化应用提供理论依据。     

CO2气体保护焊产生飞溅的原因及控制措施

熔滴飞溅是CO2气体保护焊影响生产效率、焊接稳定性和焊缝质量的主要因素。大滴过渡和短路过渡都会产生飞溅。分析飞溅的成因,采取有针对性的控制飞溅的有效措施,采用合理的焊接工艺、选择合理的焊接工艺参数降低飞溅率,对CO2气保焊有着十分重要的意义。