植物蛋白质组学研究进展

蛋白质组学在当代基因组研究中占据重要地位。近年来,蛋白质组学技术在农业中的应用愈加广泛,大大加快了农业科学的研究进程。文章综述了蛋白质组学的研究内容、常用技术以及在农业中的应用,为进一步发展研究提供思路。

流式细胞术的发展及在植物研究中的应用

流式细胞术是通过对液流中各种荧光标记的颗粒进行多参数快速高效的定性或定量测定的方法,在科学研究的多个领域发挥重要作用。然而,由于植物组织及细胞壁和次生代谢产物等细胞的特殊成分和结构,限制了其在植物研究领域的应用。本文在介绍流式细胞仪发展和组成分类的基础上,着重讨论了流式细胞术在植物领域的应用、研究进展及应用限制,进而展望该研究领域的发展趋势,为拓宽植物流式细胞术的潜在应用范围提供新的思考方向。

Progress in Research on Intercellular Movement of Protoplasm in Higher Plants

Since nuclear extrusion was rediscovered in young Allium scale by S.H.WU in the years of 1950's systematic investigations on this phenomenon were carried out with various kinds of microscopic techniques and plant materials to collect more effective evidence to clarify the debate about whether the nuclear extrusion is an artifact or normal event. In the cooperative research of S. H. WU and C. H. LOU the normality of the occurrence of nuclear extrusion either in growing part of plant or in senescent tissue has been confirmed. This event is intimately associated with the physiological state of the tissues/cells and may play an important role in redistribution and reutilization of cell contents. Based on the results obtained a hypothesis of intercellular movement of protoplasm as a means of translocation of organic material in plants was suggested. Chromatin extrusion was also discovered in the pollen mother cells (cytomixis) of certain angiosperms by G. C. ZHENG and his team. Intercellular migration of chromatin appears most frequently at the stage of synizesis. Cytomixis has been studied in relation to variation and evolution. Chromosome aberration has been considered to be closely associated with chromatin extrusion. By vital microscopic observations of the live tissues of garlic (Allium sativum L.) bud and wheat (Triticum aestivum L.) ovule combined with cinemicroscopy and video recording it has been uncovered that, not only the nuclear material but also the cytoplasm could traverse the intercellular channels by vigorous contraction and expansion, and they may simultaneously extrude out of a cell but often asynchronously migrate from one cell to another. The involvement of cytoplasmic constituents in intercellular migration was also detected in pollen mother cells with electron microscopy. Regarding the mechanism of intercellular movement a series of experiments provide convincing evidence showing that this kind of movement is an active metabolic process closely coupled with energy metabolism, and the motive power for driving the extrusion may be supplied by the contractile proteins in protoplasm.

Induction of apoptosis in purified animal and plant nuclei by Xenopus egg extracts

We have developed a cell-free system that can trigger the nuclei purified from mouse liver and suspensioncultured carrot cells to undergo apoptosis as defined by the formation of apoptotic bodies and nucleosomal DNA fragments. The effects of different divalent cations and cycloheximide on DNA cleavage in this system were assessed.The fact that nuclei of plant cells can be induced to undergo apoptosis in a cell-free animal system suggests that animals and plants share a common signal transduction pathway triggering in the initiation stage of apoptosis.

Fluorescent vital staining of plant sexual cell nuclei with DNA-specific fluorochromes and its application in gametoplast fusion

DNA-binding fluorochromes are often used for vital staining of plant cell nuclei. However, it is not always sure whether the cells after staining still remain in living state. We chose several criteria to estimate the validity of real vital staining for sexual cell nuclei. These were: the cytoplasmic streaming in pollen tubes whose nuclei were stained, the simultaneous visualization of fluo-rochromatic reaction and nucleus staining in isolated generative cells, and the capability of isolated, prestained generative or sperm cells to fuse with other protoplasts. The results confirmed that 4',6-diamidino-2-phenylindole (DAPI), Hoechst 33258 and mithramycin could be used as real vital stains, though their efficiency varied from case to case; among them DAPI showed best effect. The fluorescent vital staining technique offered a useful means fori-dentification and selection of heterokaryons in gametoplast manipulation studies.

Inhibitory effect of a new gossypol derivative apogossypolone (ApoG2) on xenograft of human prostate cancer cell line PC-3

Objective: To investigate the inhibitory effect of apogossypolone (ApoG2) on prostate cancer cell line PC-3 in vivo, and explore its mechanism. Methods: The models of transplantation tumors in Balb/c nu/nu mice were established via subcutaneous injection of PC-3 cells and the tumor-transplanted mice were divided into 4 groups: control group and three ApoG2 treatment groups, with 10 mice in each group. Volumes of the tumor were estimated every 2 d and the morphology of tumor tissues was observed. Immunohistochemistry was employed to observe the expression of Bcl-2, PCNA, CD31, caspase-3 and caspase-8 in tumor tissues. Results: ApoG2 (2.5 mg/kg-10 mg/kg) given intraperitoneally once a day can obviously inhibit the growth of subcutaneous prostatic carcinoma implant. The tumor volume decreased obviously when the treatment dosage was bigger than 5.0 mg/kg (P<0.01). Meanwhile, ApoG2 decreased the expression of PCNA and CD31, and enhanced the expression of caspases-3, caspase-8 in tumor tissues. Conclusion: ApoG2 exert an inhibitory effect on prostatic carcinoma possibly by inducing apoptosis and inhibiting tumor angiogenesis.

Distributions of Picophytoplankton and Phytoplankton Pigments Along a Salinity Gradient in the Changjiang River Estuary, China

We investigated the abundance of different picophytoplankton groups and the phytoplankton pigment ratio in relation to environmental factors such as nutrients and suspended solids along a salinity gradient in the Changjiang River Estuary.The average numbers of Synechococcus spp.（Syn） and picoeukaryotes （Euk） were （2.7 ±5.1）×l03 and （1.1±1.4）×l03 cells mL-1,respectively.Prochlorococcus spp.（Pro） was only found in the high-salinity brackish water with the concentration of 3.0× 10^3 cells mL-1.Syn and Euk numbers both tended to increase offshore and Syn showed a larger variation in cell abundance than Euk.The contribution of picophytoplankton to total phytoplankton biomass increased with increasing salinity and decreasing nutrient concentrations from the estuary to the open ocean.The response of different picophytoplankton groups to environmental variables was different.Water temperature was more important in its control over Euk than over Syn,while nutrients were more important in their influence over Syn than over Euk.Phytoplankton pigment ratios were different in the three different ecological zones along the salinity gradient （i.e.,freshwater zone with 0-5 range,fresh and saline water mixing zone with 5-20 range,and high-salinity brackish water zone with 20-32 range）,where three different phytoplankton communities were discovered,suggesting that phytoplankton pigment ratios can be considered as a complementary indicator of phytoplankton community structure in the Changjiang River Estuary.

Binding of nucleosides with the cytotoxic plant alkaloid sanguinarine:Spectroscopic and thermodynamic studies

In spite of a large number of studies of the interaction of the cytotoxic plant alkaloid sanguinarine(SAN) with nucleic acids,the anticancer mechanism of SAN is still not clear.In contrast to the large number of studies of the interaction mechanism of SAN with DNA,there have been relatively few studies of the interaction of SAN with nucleosides.In this work,the interaction of SAN with three nucleosides-thymidine(T),uridine(U),and adenosine(A)-was investigated using a combination of conventional fluorescence and UV-vis spectroscopic techniques;thermodynamic calculations were also carried out at physiological pH 7.2.The binding processes of SAN with the different nucleosides were characterized by hypochromic and bathochromic effects in the absorption spectra of SAN and by the quenching of the fluorescence intensity of SAN.The measurements of fluorescence lifetime,the variations of the absorption spectra of the fluorophore,and the dependence of the quenching on the temperature indicated that the fluorescence quenching is static.The Stern-Volmer plot is nonlinear and approximately quadratic showing that,in this process,one SAN molecule can bind with two nucleoside molecules.These studies,together with our earlier studies of the binding of SAN with cytidine(C) and guanosine(G),showed that the binding constants of SAN with the five nucleosides at T = 308.15,318.15,and 328.15 K decreased in the order C > G > T > U > A and at T = 298.15 K decreased in the order G > C > T > U > A,and that the binding of SAN with the various nucleosides is not only slightly exothermic but also entropy-driven.All these results together with fluorescence quenching experiments advance good evidence concerning the interaction of SAN with various nucleosides.Such studies of the interaction mechanism of alkaloids with DNA may promote the development of new drugs.