Peptide synthesis through evolution

Ribosome-catalyzed peptide bond formation is a crucial function of all organisms. The ribosome is a ribonucleoprotein particle, with both RNA and protein components necessary for the various steps leading to protein biosynthesis. Evolutionary theory predicts an early environment devoid of complex biomolecules, and prebiotic peptide synthesis would have started in a simple way. A fundamental question regarding peptide synthesis is how the current ribosome-catalyzed reaction evolved from a primitive system. Here we look at both prebiotic and modern mechanisms of peptide bond formation and discuss recent experiments that aim to connect these activities. In particular, RNA can facilitate peptide bond formation by providing a template for activated amino acids to react and can catalyze a variety of functions that would have been necessary in a pre-protein world. Therefore, RNA may have facilitated the emergence of the current protein world from an RNA or even prebiotic world.Received 4 December 2003; received after revision 13 January 2004; accepted 15 January 2004     

Role of VEGF in the growth and metastasis of a murine bladder carcinoma

Bladder transitional cell carcinoma is the most common form of carcinoma in the urinary system. Although overexpression of VEGF has been identified in tissue, serum,and urine of patients with bladder cancer, the role of VEGF in transitional cell carcinoma of the bladder has not been clearly elucidated. Here, we dissected the effect of VEGF during bladder tumor growth and progression by modifying a BBN (N-butyl-N-(4-hydroxybutyl) nitrosamine) induced mouse bladder transitional cell carcinoma cell line BTT-T739 by stable transfection of antisense VEGF121 cDNA. The transfection resulted in-more than 80% reduction in VEGF production. The growth of the transduced tumor cells in vitro was not affected, however, these cells formed small or no tumors in vivo. Even in the tumors formed, there were minimal vascularization, extensive necrosis and longer latency compared to those formed by parental cells. The permeability of tumor vasrulatuce and metastatic tumor growth were also significantly suppressed in antisense VEGF cDNA transfected cells. In addition, the transfer of anti-angiogenic gene in a rumbination of sFlk-I and ExTek with electroporation can suppress the tumor growth efficiently. Taken together,these results demonstrated that VEGF plays an important role in bladder tumor angiogenesis and angiogenesis plays an important role in bladder tumor growth and metastasis.     

绿豆子叶脱分化过程核酸代谢的研究

本文研究了绿豆(Phaseolus raditus L.cv.D317—1)子叶切段在激素诱导下脱分化过程中DNA和RNA代谢的变化。子叶切段在附加1ppm激动素(KT)和4PPm萘乙酸(NAA)的Miller培养基上表现出较高的脱分化能力。DNA含量和RNA含量在离体培养的前7天增加约2倍,随后DNA含量维持不变,而RNA含量仍缓慢增加;利用同位素掺入法测定的DNA和RNA合成速率,在培养早期迅速增加,第5天时分别增加了2倍和4倍,随后虽有所降低,但仍处于较高水平;DNase和RNase(pH4.5,pH7.5)活性在培养早期有所降低,随后不断增强。这些结果表明,绿豆子叶切段的脱分化过程伴随着DNA和RNA代谢的加强,特别是合成作用,这可能是子叶脱分化的主要代谢特征之一。     

Inhibitory effect of flavonoids on DNA-dependent DNA and RNA polymerases

Summary Flavonoids, (–)-epigallocatechin (1), myricetin (2) and quercetin (3), were investigated for inhibitory effects onE. coli DNA polymerase I and T7 bacteriophage RNA polymerase. In both DNA and RNA synthesis,1 and3 inhibited enzyme reactions by non-competitive and mixed type inhibition respecitively, with regard to template DNAs. Myricetin (2) inhibited DNA and RNA polymerase reactions by mixed type and competitive type inhibition, respectively, with template DNAs. It was suggested that2 interacts with covalently closed/circular DNA.     

激光热透镜光谱技术对核酸浓度的定量测定

作为一种灵敏度极高的光谱技术——激光热透镜光谱技术,现已被应用于许多研究领域,并日益受到人们的重视.本文是我们在前人工作的基础上,首次将该技术应用于核酸浓度的定量测定,分析灵敏度达到10~(-3)g/ml,实验结果证明将激光热透镜光谱技术应用于光生物这一领域,为核酸的研究提供了一种快速、简便、灵敏的分析方法.     

Autoradiographic studies on RNA synthesis and transport in the ovary ofHydrophilus olivaceus fabr. (Hydrophilidae,Polyphaga, Coleoptera)

Summary Autoradiographic studies using³H-uridine in the ovary ofHydrophilus olivaceus Fabr. show that nurse cells, the germinal vesicle and follicular nuclei play an important role in contributing RNA whereby the major portion of RNA comes from the nurse cells.I am grateful to Prof. P. S. Ramamurty, School of Life Sciences, University of Hyderabad, Hyderabad, India, for his constant inspiration during the tenure of the present investigation.     

Antisense expression of a rice cellular apoptosis susceptibility gene (OsCAS) alters the height of transgenic rice

Cellular apoptosis susceptibility (CAS) gene plays important roles in mitosis, development and export of importin α from the nucleus, but its function in plant is unknown. In this study, a rice CAS ortholog (OsCAS), which encodes a predicted protein of 983 amino acids with 62% similarity to human CAS, was identified. DNA gel blot analysis revealed a single copy of OsCAS in the rice genome. A 973 bp fragment at the 3′ end of OsCAS cDNA was cloned from rice cDNA library and transferred into rice in the antisense direction under the control of CaMV 35S promoter via Agrobacterium-mediated transformation method, 105 transgenic lines were obtained. Expression of OsCAS was suppressed in the antisense transgenic lines as revealed by semi-quantitative RT-PCR. The antisense transgenic lines showed dwarf phenotypes. The results indicated that OsCAS was involved in culm development of rice.