Lipidomic changes during different growth stages of Nitzschia closterium f. minutissima

Ultra Performance Liquid Chromatography-Electrospray ionization-Quadrupole-Time of Flight Mass Spectrometry (UPLC-ESI-Q-TOF–MS) is a powerful lipidomic tool. In this study, we developed a UPLC/Q-TOF–MS based method to investigate the lipid metabolomic changes in different growth phases of Nitzschia closterium f. minutissima. The data classification and biomarker selection were carried out by using multivariate statistical analysis, including principal components analysis (PCA), projection to latent structures with discriminant analysis (PLS-DA), and orthogonal projection to latent structures with discriminant analysis (OPLS-DA). We discovered that the intercellular lipid metabolites were significantly different among exponential, early stationary and late stationary phases. Thirty-one lipid molecules were selected and identified as putative biomarkers, including free fatty acid, Harderoporphyrin, phosphatidylglycerol, 1,2-diacyglycerl-3-O-4′-(N,N-trimethy)-homoserine, triacylglycerol, cholesterol, sulfoquinovosyldiacylglycerol, lyso-sulfoquinovosyldiacylglycerol, monogalactosyldiacylglycerol, digalactosyldiacylglycerol and lyso-digalactosyldiacylglycerol. These lipids have been shown previously to function in energy storage, membrane stability and photosynthesis efficiency during the growth of diatoms. Further analysis on the putative biomarkers demonstrated that nitrate starvation played critical role in the transition from exponential phase to stationary phase in N. closterium. This study is the first one to explore the lipidomic changes of microalgae in different growth phases, which promotes better understanding of their physiology and ecology.     

mRNA差别显示技术及其在生命科学中的应用

ｍＲＮＡ表达水平的变化决定细胞的功能状态,个体发育、细胞增殖分化与凋谢、生理刺激和药物治疗等过程,都会出现ｍＲＮＡ 表达水平的变化。阐明这种变化有助于揭示细胞生理过程的分子机制。该技术无需更多的背景资料,可快速有效地分离表达水平出现差别的基础,这些基因编剧编码的功能多肽在细胞生理过程中扮演着重要角色。     

Development of a seed DNA-based genotyping system for marker-assisted selection in maize

Leaf collection from the field, labeling and tracking back to the source plants after genotyping are rate limiting steps in leaf DNA-based genotyping. In this study, an optimized genotyping method using endosperm DNA sampled from single maize seeds was developed, which can be used to replace leaf DNA-based genotyping for both genetic studies and breeding applications. A similar approach is likely to be suitable for all plants with relatively large seeds. Part of the endosperm was excised from imbibed maize seeds and DNA extracted in 96-tube plates using individuals from eight F₂ populations and seven inbreds. The quality of the resultant DNA was functionally comparable to DNA extracted from leaf tissue. Extraction from 30 mg of endosperm yields 3–10 μg DNA, which is sufficient for analysis of 200–400 agarose-gel PCR-based markers, with the potential for several million chip-based SNP marker analyses. By comparing endosperm DNA and leaf DNA for individuals from an F₂ population, genotyping errors caused by pericarp contamination and hetero-fertilization were found to average 3.8 and 0.6%, respectively. Endosperm sampling did not affect germination rates under controlled conditions, although under normal field conditions the germination rate, seedling establishment, and growth vigor were significantly lower than that of non-sampled controls for some genotypes. However, careful field management can compensate for these effects. Seed DNA-based genotyping lowered costs by 24.6% compared to leaf DNA-based genotyping due to reduced field plantings and labor costs. A substantial advantage of this approach is that it can be used to select desirable genotypes before planting. As such it provides an opportunity for dramatic improvements in the efficiency and selective gain of breeding systems based on optimum combinations of marker-assisted selection and phenotypic selection within and between generations.     

5种光合细菌种间原生质体融合及优良农用融合子的筛选鉴定

处于对数生长期的光合细菌球形红假单胞菌(Rhodopseudomonassphaeroides)、沼泽红假单胞菌(Rhodopseudomonaspalustris)、嗜酸红假单胞菌(Rhodopseudomdnasacidophila)、深红红螺菌(Rhodospirarubrum)、万尼氏红微菌(Rhodomocrobiumvannielii),经溶菌酶(3mg/L)处理50min后,获得了它们的菌体形成的原生质体,其再生率分别为80%、71%、82%、61%、74%.取等量的亲本菌株在35%的PEG(MW6000)诱导下两两融合5min,共10种组合.其融合率为球×沼2.5×10-4、球×嗜2.1×10-4、球×深2.0×10-4、球×万2.1×10-4、沼×嗜2.8×10-4、沼×深2.4×10-4、沼×万2.6×10-4、嗜×深2.0×10-4、嗜×万2.3×10-4、深×万2.4×10-4.经影印法鉴定:形成的融合子可以分别生长于以相应的有机物为唯一碳源的培养基上,所有融合子体积均相当于两亲本株体积之和,融合子菌落形态特征介于两亲本株之间.从中随机挑选100个融合子,以辣椒苗作为靶标植物,从上述融合子中筛选到了1株具有显著促进作物生长、提高抗病性的融合子.     

间断低氧对大鼠下丘脑超微结构及前增食欲素水平的影响

目的探讨睡眠中间断低氧对大鼠下丘脑前增食欲素及受体水平的影响以及下丘脑超微结构的变化。方法大鼠分成对照组、间断低氧组和持续低氧组,分别给予吸入空气,持续低氧和间断低氧气体,并在实验开始后1d、3d、1w和4w应用RT-PCR方法测定大鼠下丘脑前增食欲素及受体水平,分析其间的变化关系,电镜观察下丘脑的超微结构变化。结果与对照组和持续低氧组比较,间断低氧4w后大鼠下丘脑前增食欲素mRNA水平明显降低,受体水平升高,但在持续低氧和对照组之间无明显差异。在低氧后1d、3d、7d后大鼠下丘脑前增食欲素mRNA降低,受体水平升高,在4w后,持续低氧组则接近正常。急性持续低氧大鼠超微结构变化更严重,而慢性间断低氧变化更持久。结论慢性间断低氧可以引起下丘脑前增食欲素下降及受体水平升高,急性持续低氧也可引起上述变化,而慢性持续低氧未引起增食欲素改变;慢性间断低氧大鼠下丘脑超微结构表现为严重而持久的变化。