Production of cyanophycin, a suitable source for the biodegradable polymer polyaspartate, in transgenic plants

The production of biodegradable polymers in transgenic plants in order to replace petrochemical compounds is an important challenge for plant biotechnology. Polyaspartate, a biodegradable substitute for polycarboxylates, is the backbone of the cyanobacterial storage material cyanophycin. Cyanophycin, a copolymer of l-aspartic acid and l-arginine, is produced via non-ribosomal polypeptide biosynthesis by the enzyme cyanophycin synthetase. A gene from Thermosynechococcus elongatus BP-1 encoding cyanophycin synthetase has been expressed constitutively in tobacco and potato. The presence of the transgene-encoded messenger RNA (mRNA) correlated with changes in leaf morphology and decelerated growth. Such transgenic plants were found to produce up to 1.1% dry weight of a polymer with cyanophycin-like properties. Aggregated material, able to bind a specific cyanophycin antibody, was detected in the cytoplasm and the nucleus of the transgenic plants.     

Protochlorophyllide and POR development in dark‐grown plants with different proportions of short‐wavelength and long‐wavelength protochlorophyllide spectral forms†

The effect of leaf developmental age on the protochlorophyllide (Pchlide) spectral forms and the expression of messenger RNA (mRNA) encoding NADPH‐protochlorophyllide oxidoreductase (POR) were investigated. Four plant species, maize, wheat, pea and the lip1 mutant of pea, known to have different composition of the spectral forms of Pchlide, were used. In very young plants short‐wavelength Pchlide with a fluorescence emission at 631 nm was dominating. Long‐wavelength Pchlide fluorescing mainly around 655 nm increased during development, which led to a relative decrease of the short‐wavelength forms. During ageing of the leaves, the short‐wavelength forms slightly increased again. The different proportions of short‐ and long‐wavelength Pchlide spectral forms were, however, found to vary with the developmental stage in a species specific pattern. The steady‐state level of POR mRNA and the amount of the POR protein were similar in species dominated by short‐wavelength forms and in species dominated with long‐wavelength forms. Even if POR is necessary for the formation of the long‐wavelength Pchlide form it is not the only limiting factor for formation of long‐wavelength Pchlide forms in mature plants.     

Efficient suppression of tissue factor synthesis using antisense oligonucleotides selected by an enhanced strategy for evaluation of structural characteristics

Selection of optimal antisense constructs is still a problem. Among a huge number of antisense oligonucleotides (AS-ONs) only a small piece show inhibitory efficacy. We want to develop an enhanced strategy for specific selection of effective AS-ONs based on prediction of secondary structure of the target messenger RNA (mRNA) and analysis of thermodynamic properties of the mRNA/AS-ON hybrid. Numerous AS-ONs targeted on human tissue factor (TF) mRNA were investigated to evaluate the relevance of different thermodynamic and structural properties on inhibitory efficacy. Cell viability, TF protein and TF mRNA were determined after transfection of bladder cancer cell line J82. Inhibitory efficacy was related to GC content, target region within the TF mRNA and stability of the mRNA/AS-ON hybrid or affinity of the AS-ON to the target mRNA. We found effective AS-ONs targeted on translated region or 3'-untranslated region of TF RNA. We also detected a great correlation between inhibitory efficacy and GC content as well as stability of the mRNA/AS-ON hybrid.     

Analysis of rice Act1 5' region activity in transgenic rice plants.

The 5' region of the rice actin 1 gene (Act1) has been developed as an efficient regulator of foreign gene expression in transgenic rice plants. To determine the pattern and level of rice Act1 5' region activity, transgenic rice plants containing the Act1 5' region fused to a bacterial beta-glucuronidase (Gus) coding sequence were generated. Two independent clonal lines of transgenic rice plants were analyzed in detail. Quantitative analysis showed that tissue from these transgenic rice plants have a level of GUS protein that represents as much as 3% of total soluble protein. We were able to demonstrate that Act1-Gus gene expression is constitutive throughout the sporophytic and gametophytic tissues of these transgenic rice plants. Plants from one transgenic line were analyzed for the segregation of GUS activity in pollen by in situ histochemical staining, and the inheritance and stability of Act1-Gus expression were assayed in subsequently derived progeny plants.     

植物非编码RNA的研究进展

非编码RNA(non-coding RNA, ncRNA)是一类广泛存在于多种生物体中,缺乏明确的开放阅读框,不编码蛋白质的RNA分子.目前已从部分植物中分离到一些ncRNA,它们直接以RNA分子的形式在植物体内发挥重要的调节功能,影响细胞分化和个体发育、基因转录调控、mRNA稳定性、RNA加工与修饰、信号传导、以及环境适应调节等.植物ncRNA的研究为深入了解植物的生长发育及系统进化提供了重要信息.