大气CO2浓度升高对香蕉光合作用及光合碳循环过程中叶氮分配的影响

生长在高CC2浓度(700±56μl     

插入序列共同区元件：细菌中新出现的一种基因捕获系统

摘要：插入序列共同区（Insertion sequence common region,ISCR）元件是一类在结构和功能上与IS91家族相似的特殊插入序列,特点是缺少了末端反向重复序列（Inverted repeats, IRs）,在插入位点不产生直接重复序列,并通过滚环式（Rolling circle, RC）进行转座。ISCR元件作为一种新的基因捕获系统,它可以移动邻近的任何DNA序列,为耐药基因在不同种属细菌间水平传播提供了高效的媒介。世界各地多种革兰氏阴性病原菌中已发现有19种ISCR元件,大部分ISCR元件同时携带了多种耐药基因,提示ISCR有可能会造成细菌多重耐药性的快速传播。本文就ISCR结构特征、类型、移动方式、起源及进化的研究进展进行了综述。     

海洋固氮菌和解磷菌的分离鉴定及发酵条件优化

【目的】从西沙喜盐草根际沉积物中分离纯化得到具有高效固氮能力及解磷能力的菌株。优化其发酵培养条件,研究其制备海洋微生物菌剂的可能性。【方法】从形态学特征、生理生化、16S rDNA及功能基因水平进行鉴定,通过乙炔还原法、钼锑抗显色法检测菌株的固氮酶活性和解磷能力,单因素法和响应面法优化其发酵培养条件,溶血试验和急性毒性实验鉴定菌株的安全性。【结果】结果表明,菌株AZ16属于星箭头菌(Sagittula stellate),革兰氏阴性菌,选择性固氮培养基中菌落呈黄圆形黏稠状,固氮酶活性达34.63 nmol C2H2/(mL·h),最适生长条件为:盐度25‰、pH 7.5、温度33°C、接种量5.0%;菌株XT37为海洋芽孢杆菌(Bacillus sp.),革兰氏阳性菌,选择性固氮培养基中菌落呈深黄色圆形褶皱,植酸酶活性达239.49μg/L,最适合生长条件为:盐度25‰、pH 6.7、温度28°C、接种量5.0%。溶血实验和急性毒性实验证明两株菌属实际无毒级别。【结论】两株菌具有高效的固氮解磷功能,以及抗高盐、强碱等环境的能力,安全无毒,因此有潜力应用于多功能混合微生物菌剂的研制。     

Redox regulation of plant stem cell fate

Despite the importance of stem cells in plant and animal development, the common mechanisms of stem cell maintenance in both systems have remained elusive. Recently, the importance of hydrogen peroxide (H₂O₂) signaling in priming stem cell differentiation has been extensively studied in animals. Here, we show that different forms of reactive oxygen species (ROS) have antagonistic roles in plant stem cell regulation, which were established by distinct spatiotemporal patterns of ROS‐metabolizing enzymes. The superoxide anion () is markedly enriched in stem cells to activate WUSCHEL and maintain stemness, whereas H₂O₂ is more abundant in the differentiating peripheral zone to promote stem cell differentiation. Moreover, H₂O₂ negatively regulates biosynthesis in stem cells, and increasing H₂O₂ levels or scavenging leads to the termination of stem cells. Our results provide a mechanistic framework for ROS‐mediated control of plant stem cell fate and demonstrate that the balance between and H₂O₂ is key to stem cell maintenance and differentiation.     

应用明胶颗粒凝集试验检测人免疫缺陷病病毒(HIV-1)抗体

明胶颗粒凝集试验是测定HIV-1抗体的新方法。本研究将明胶颗粒凝集试验与ELISA法、蛋白印迹法和间接免疫荧光试验做了比较,观察本方法的敏感性和特异性。共检测了195份来自法国和非洲象牙海岸的血清,凡是蛋白印迹法阳性的血清,明胶颗粒凝试验都是阳性。这表明本方法是特异和敏感的,方法简便,不需特殊仪器,省时,可用于HIV-1抗体的筛选,但多数蛋白印迹法可疑的血清,明胶颗粒试验均阴性。因此,对蛋白印迹法测出的可疑者应该用数种方法进行追踪检测。     

Metabolic dynamics across prolonged diapause development in larvae of the sawfly,Cephalcia chuxiongica (Hymenoptera: Pamphiliidae)

Nutrient metabolism is crucial for the survival of insects through the diapause. However, little is known about the metabolic mechanism of prolonged diapause. The sawfly, Cephalcia chuxiongica (Hymenoptera: Pamphiliidae), is a notorious defoliator of pine trees in southwest China. One of the distinguishing biological characteristics of this pest is the prolonged diapause of about 1.5 years. In this study, the body lipid, carbohydrate (total body sugar, glycogen, trehalose, and glucose), protein, and glycerol contents were measured in diapausing larvae of C. chuxiongica. The results showed that the changes of biochemical composition in C. chuxiongica are associated with the diapause initiation, maintenance, and termination phases. During the initiation phase, trehalose, glucose, and glycerol increased significantly, but glycogen decreased sharply. In general, the lipid, carbohydrate, and glycerol levels decreased gradually across the maintenance phase. At termination phase, the contents of glycogen and lipid persistently decreased, while an increase of trehalose, glucose, and glycerol contents were detected. The protein level was significantly higher at maintenance phase than at initiation and termination phases. It was also found that elevation of trehalose, glucose, and glycerol contents occurred in winter. These implies that the metabolites with altered levels in diapausing larvae of C. chuxiongica are responsible for maintaining a prolonged development and overwintering.     

The histone demethylases Jhdm1a/1b enhance somatic cell reprogramming in a vitamin-C-dependent manner

Reprogramming of somatic cells into induced pluripotent stem cells (iPSCs) resets the epigenome to an embryonic-like state. Vitamin C enhances the reprogramming process, but the underlying mechanisms are unclear. Here we show that the histone demethylases Jhdm1a/1b are key effectors of somatic cell reprogramming downstream of vitamin C. We first observed that vitamin C induces H3K36me2/3 demethylation in mouse embryonic fibroblasts in culture and during reprogramming. We then identified Jhdm1a/1b, two known vitamin-C-dependent H3K36 demethylases, as potent regulators of reprogramming through gain- and loss-of-function approaches. Furthermore, we found that Jhdm1b accelerates cell cycle progression and suppresses cell senescence during reprogramming by repressing the Ink4/Arf locus. Jhdm1b also cooperates with Oct4 to activate the microRNA cluster 302/367, an integral component of the pluripotency machinery. Our results therefore reveal a role for H3K36me2/3 in cell fate determination and establish a link between histone demethylases and vitamin-C-induced reprogramming.     

1,4—二取代酰氨基硫脲类化合物(DATCDs)的植物生理效应与应用研究——Ⅴ.DATCD-A对离体黄瓜子叶扩张及核酸代谢的影响

本实验以离体黄瓜子叶为材料,研究了 DATCD—A 对子叶扩张及核酸代谢的影响。结果表明,DATCD—A 可显著地促进离体黄化子叶扩张,使其鲜重明显增加;并且在处理后期逐渐提高子叶干重。在离体子叶扩张变绿的过程中,DATCD—A 促进离体黄化子叶 RNA、DNA 含量和 DNA/RNA 比率明显上升,且 RNA 的增加发生在 DNA 合成增加之前。凝胶电泳证明,RNA 的增加主要是25s 和18s 的 rRNA。     

底栖生物影响下的潮滩微地貌演化数值模拟

潮滩是海岸带湿地的主要类型之一,其中分布的底栖生物对生态环境具有重要的调节作用。潮滩底栖微藻、泥沙与水动力之间存在相互作用,影响潮滩微地貌形态,明晰底栖生物对潮滩微地貌的演化机制至关重要。以黄河三角洲潮滩湿地为研究区,通过构建潮滩微地貌动力模型,探究底栖生物对微地貌格局演化的作用机制,分析底栖生物对微地貌系统稳定性的影响。结果表明(1)底栖微藻生长与泥沙扩散、水流再分配过程交互作用驱动下,潮滩上可形成底栖微藻覆盖的高丘与积水洼地交替分布的规则性微地貌斑图;(2)微地貌斑图的形成提高了潮滩生态系统初级生产力和泥沙淤积高度;(3)底栖微藻与泥沙、水流的交互作用使得潮滩微地貌系统对侵蚀扰动呈现非线性响应行为,系统存在临界点,且在一定侵蚀率范围内存在双稳态;(4)黄河口泥螺入侵使得微地貌系统抵抗侵蚀扰动能力减小,且系统稳定性随泥螺生物量的增加而降低。     

柑橘全爪螨空间格局与抽样技术的研究

本应用空间分布型统计参数IwaoM-X模型中α,β及6个聚集指标分析了柑橘全爪螨的空间格局,并对抽样技术进行了探讨。结果表明,柑橘全爪螨的空间格局为聚集型;田间的抽样部位是上、中、下三部的叶片。提出了估算柑橘全爪螨在不同虫口密度下的理论抽样数。