Analysis of mating type determination by transplantation of O macronuclear karyoplasm in Paramecium tetraurelia

The odd (O) or even (E) mating type in Paramecium tetraurelia is determined during the first cell cycle after new macronuclear development. The present paper demonstrates that mating type E is irreversibly determined at the end of the first cell cycle. Direct evidence comes from transplanting O macronuclear karyoplasm containing O-determining factor into E autogamous cells during a new postzygotic macronuclear development. Transplantation of O macronuclear karyoplasm into E autogamous cells at 7–8 hr after the origin of the macronucleus from a product of the synkaryon produces nearly 100% O mating type among the exautogamous cell lines but almost none 10–11 hr after the origin of the macronucleus (around the end of the first cell cycle). The macronuclear anlagen at the stage at which mating type E seems to be fixed contains about 20 times as much DNA as the vegetative G1 micronucleus. The O-determining factor shifting E cells toward O mating type by transplanting O macronuclear karyoplasm is also produced by the newly developed macronucleus in an effective concentration at 10–11 hr after the sensitive period and produced at full levels by the third cell cycle. The level of O factor in the macronucleus then gradually declines with subsequent repeated rounds of DNA synthesis and is finally lost by the eighth cell cycle.     

侧脑室内注射微量五肽胃泌素对大鼠胃肠推进运动的影响

以炭粉混悬液在大鼠小肠内推进距离占小肠全长的百分数,作为胃肠推进运动的指标,观察了侧脑室内注射微量五肽胃泌素(G_5)对这一推进运动的影响。结果如下:(1)侧脑室内(ICV)注射c_5(1μg/10μl、2μg/10μl 或4μg/10μl)可显著增强胃肠推进运动(P<0.01—0.001)。切断两侧膈下迷走神经、阿托品皮下(0.2mg/kg)或侧脑室内(5μg/10μl)注射均可完全阻断这一增强效应(P<0.001)。(2)肌注较大剂量G_5(20μg/100g)可显著增强胃肠推进运动(P<0.001),这一效应亦可为皮下注射阿托品(0.2mg/kg)所完全阻断(P<0.001)。(3)酚妥拉明(2.5mg/kg im或50g/10μl ICV)或心得安(5mg/kgim或50μg/50μl ICV)对侧脑室内注射G_5增强胃肠推进运动的作用均无影响(P>0.05)。上述结果表明侧脑室内注射G_5后,可能激活中枢胆硷能系统,通过迷走神经而使胃肠推进运动增强。     

Erythrocyte-mediated microinjection of horseradish peroxidase into BHK cells

In order to establish the distribution with time of proteins microinjected into mammalian cells, horseradish peroxidase (HRP) was microinjected into baby hamster kidney (BHK) cells using chicken erythrocyte ghosts. At time intervals following initiation of fusion between ghosts and target cells, samples were fixed with aldehydes and the peroxidase visualized by reaction with diaminobenzidine and viewing by light and electron microscopy. At 10 min, the reaction product was observed within the cytoplasm of 60% of the microinjected cells, but was excluded from the nucleus and membranous organelles. In the other 40% of microinjected cells, the reaction product was also observed within the nucleus. At 30 min, the reaction product was observed to be evenly distributed throughout the cell, including the nucleus but excluded from organelles. By 6 h, the reaction product was present almost exclusively within the nucleus of 63% of microinjected cells. At all time points, 20–30% of the erythrocytes ghosts appear to have been taken up by cells by phagocytosis rather than fusion, as evidenced by the presence of peroxidase reaction product within intact and fragmented erythrocyte ghosts in the cytoplasm of target cells. Cells incubated with a lanthanum solution following fusion excluded this electron dense tracer, indicating that the cytoplasmic compartment is not opened during exposure to polyethylene glycol.     

兔延髓闩区微量注射谷氨酸钠对呼吸节律的影响

本工作在21只氨基甲酸乙酯麻醉、自主呼吸的家兔上,以膈肌肌电平均积分信号作为检测呼吸频率和幅度的指标,观察了在延髓闩区微量注射细胞体兴奋剂谷氨酸钠对呼吸节律的影响。结果表明:闩区表浅脑组织内微量注射谷氨酸钠后动物呼吸频率明显增加,与前对照相比,1min后平均增加27±5次/min,2min后平均增加32±5次/min,与NaCl对照组比较,P<0.001。结果提示:兔延髓闩区临近的表浅脑组织可能参予调节或影响呼吸节律活动。     

Structure and function of poly(ADP-ribose) polymerase

Poly(ADP-ribose) polymerase (PARP) participates in the intricate network of systems developed by the eukaryotic cell to cope with the numerous environmental and endogenous genetoxic agents. Cloning of the PARP gene has allowed the development of genetic and molecular approaches to elucidate the structure and the function of this abundant and highly conserved enzyme. This article summarizes our present knowledge in this field.     

An Immunocytochemical Technique for Analysis of Regulation of Genes Encoding Early Differentiation Marker Antigens in an Oocyte Translation System

Monoclonal antibodies are useful probes for analyzing cells at the molecular level at various developmental stages. Although identification of the genes encoding tissue- and stage-specific antigens could be informative for further molecular analysis, gene cloning is usually a time-consuming step, particularly when a monoclonal antibody is the only probe available. We describe here an immunocytochemical method for preliminary and immediate analysis of the regulation of antigen-coding genes. mRNAs purified from stage 27 and 38 Xenopus tadpoles were fractionated by size and injected into newt oocytes, from which frozen sections were prepared for immunostaining with tissue-specific monoclonal antibodies. Both of the antigens we tested, which are early markers for differentiating epidermal cells of Xenopus tadpoles, were detected in mRNA injected oocytes, but not in control oocytes. Immunostaining for each of the antigens showed that their relative levels in stage 27 and 38 tadpole tissue were reflected in those oocytes injected with mRNA purified from tadpoles of the respective stages. We suggest that this oocyte translation system combined with immuaostaining provides for rapid analysis of changes in levels of antigen coding mRNAs throughout development.     

大鼠胆碱酯酶mRNA在卵母细胞中的表达

ＡＧＰＣ法是一种快速、简便、有效的ＲＮＡ提取方法。参照该法自新生大鼠脑组织中提取出总ＲＮＡ,进一步通过ｏｌｉｇｏ（ｄＴ）－纤维素亲和层析分离获得ｐｏｌｙ（Ａ）￣＋ＲＮＡ。当ｐｏｌｙ（Ａ）￣＋ＲＮＡ或总ＲＮＡ经显微注射法进入非洲爪蟾卵母细胞后,其翻译系统能够利用外源ｍＲＮＡ合成具有催化活性的胆碱酯酶。表达的胆碱酯酶大部分分泌到卵母细胞培养液中。在一定范围内,ｍＲＮＡ的注射量与胆碱酯酶的表达量成正比。所合成的胆碱酯酶活性可被毒扁豆碱和Ｓ－（２－二异丙基氨乙基）甲基硫赶膦酸乙酯（ＶＸ）抑制。     

大鼠中缝隐核增强dPAG诱导的vPAG的c－Fos表达及对vPAG神经元放电的影响

本实验通过Ｐｏｓ免疫细胞化学、电生理及微量注射法对中缝隐核（ＮＲＯ）的交感抑制作用的相关途径进行探讨。实验在成巴比妥钠或α－氯醛糖和氨基甲酸乙脂麻醉的Ｓｐｒａｇｕｅ－Ｄａｗｌｅｙ（ＳＤ）大鼠上进行。同时予以ＮＲＯ,中脑导水管周围灰质背侧部（ｄＰＡＧ）方波脉冲串刺激,诱导中脑和延髓的ｃ－Ｆｏｓ表达。刺激ＮＲＯ过程中,基础血压升高（Ｐ＜０．０５）,刺激ｄＰＡＧ引起的防御性升压反应则减少（Ｐ＜０．０１）;中脑导水管周围灰质腹侧部（ｖＰＡＧ）、巨细胞旁外侧核（ＰＧＬ）的Ｆｏｓ样免疫阳性反应（ＦＬＩ）细胞计数分别为６６．５±８．３和１０．８±１．５（刺激ＮＲＯ＋ｄＰＡＧ组）,较单独刺激ｄＰＡＧ组明显增加,Ｐ值分别小于０．０１和０．００１;单或双脉冲刺激中缝隐核在ｖＰＡＧ可以记录到相关单位,其中８４％为兴奋单位,抑制单位占１６％。双侧ｖＰＡＧ内微量注射利多卡因（每侧２μｇ／０．１μｌ）,基础血压无明显变化,而刺激ＮＲＯ引起的降压反应幅度减小（Ｐ＜０．０１）,提示,延髓腹外侧区（ＶＬＭ）、ＮＲＯ存在不同功能分化的神经元;ＮＲＯ可能有向ｖＰＡＧ的兴奋性投射,此投射可加强ＮＲＯ的交感抑制效应。     

Dynamic analysis of drug action on in vitro reconstituted thyroid follicle by microinjection of tracer molecules and videomicroscopy

Thyroid cells isolated from the gland by trypsinization are capable in culture of reconstituting histiotypic structures, the thyroid follicles. This morphological differentiation requires the presence of the main thyroid regulator; thyrotropin. We have analyzed some structural and functional aspects of in vitro reconstituted thyroid follicles (RTF) using microinjection of fluorescent probes and videomicroscopy. This experimental approach allowed to visualize biological processes and actions of drugs, signalling factors, etc. in living cells. We describe here some examples of what can be studied with this powerful still-undervalued method. Microinjection of a cell-impermeant fluorescent probe of either high or low molecular mass into the lumen of RTF allowed to check the tightness of this compartment and therefore to analyze the control of tight junctions assembly. A small cell-impermeant probe like Lucifer Yellow microinjected into a cell was used to demonstrate and then to study the regulation of cell to cell communication via gap junctions. The presence of calcium in the lumen of RTF was detected by microinjection of a properly designed probe: Calcium Green which becomes fluorescent in the presence of the ligand. The lumen to cell transport or endocytosis of thyroglobulin, the thyroid prohormone, which is stored into the lumen of the follicles, is currently studied by microinjection of TRITC-labeled thyroglobulin. Coupled to image processing and videorecorder systems, kinetic analysis and quantitative measurements can be performed.Abbreviations CG Calcium Green - FITC-D Dextran labeled with fluorescein isothiocyanate - LY Lucifer Yellow - RTF Reconstituted thyroid follicle - Tg Thyroglobulin - Tg-TRITC Thyrogloblin labeled with tetramethyl rhodamine isothiocyanate - TSH Thyrotropin     

Application of microinjection techniques to plant nutrition

To gain a full understanding of the complex processes that underlie plant nutrition requires the elucidation of the genetic, molecular, biochemical, biophysical, physiological and environmental factors that interact, at the cellular, organ and whole plant levels, to allow this sessile organism to optimize the allocation and utilization of available resources. The application of microinjection methods, in conjunction with molecular tools, established a powerful experimental approach to elucidate the processes underlying plant growth and development. Besides providing insight into the molecular nature of many of the membrane transport systems that function in nutrient acquisition and transport, this approach revealed the presence of a unique plasmodesmal macromolecular trafficking system that operates at the cellular/tissue and whole-plant level. This information processing network it discussed in terms of its role in allowing plants to regulate physiological activities at a supracellular level. Future studies aimed at identifying additional genes associated with this plasmodesmal macromolecular trafficking system will advance our understanding of the function and evolution of this novel plant communication system.