裂殖酵母性生命周期的显微镜
Summary
We provide a reproducible basic method for the long-term microscopy of the fission yeast sexual lifecycle. With minor adjustments described, the presented protocol allows research focus on different steps of the reproductive process.
Abstract
The fission yeast Schizosaccharomyces pombe has been an invaluable model system in studying the regulation of the mitotic cell cycle progression, the mechanics of cell division and cell polarity. Furthermore, classical experiments on its sexual reproduction have yielded results pivotal to current understanding of DNA recombination and meiosis. More recent analysis of fission yeast mating has raised interesting questions on extrinsic stimuli response mechanisms, polarized cell growth and cell-cell fusion. To study these topics in detail we have developed a simple protocol for microscopy of the entire sexual lifecycle. The method described here is easily adjusted to study specific mating stages. Briefly, after being grown to exponential phase in a nitrogen-rich medium, cell cultures are shifted to a nitrogen-deprived medium for periods of time suited to the stage of the sexual lifecycle that will be explored. Cells are then mounted on custom, easily built agarose pad chambers for imaging. This approach allows cells to be monitored from the onset of mating to the final formation of spores.
Introduction
虽然两个小区之间的基因交换是有性繁殖中心事件，它依赖于促进细胞分化，允许合作伙伴的选择，进行细胞 – 细胞融合和维持基因组稳定性的事件链。因而性生命周期呈现本身作为一个模型系统以研究了许多关于发育开关生物学问题，响应于外在刺激，质膜融合，染色体分离等探索裂殖酵母性周期来研究这些现象带来的好处模型系统强大的基因，建立了完善的高通量的方法和先进的显微镜。性裂殖酵母是P细胞和不同交配类型的M-细胞之间的异型事件。两种细胞类型中差异表达许多基因1,2-包括那些用于生产分泌P-的和M-外激素，信息素受体MAP3和Mam2以及信息素山龙眼的SES Sxa1和Sxa2。同宗配合菌株，如常用的H90株，携带两种交配型的遗传信息在单个基因组和细胞经历的交配型开关在整个分裂周期（在文献3中综述）的复杂模式。异宗裂殖酵母的多个分离物很少或从不切换交配型也是常用的4，最突出的是H + N（P型）和h -S（M型）的菌株。
在裂殖酵母，进入生命周期中的性正在严格的营养调控。只有氮饥饿裂殖酵母细胞有丝分裂逮捕繁殖和产生扩散信息素信号交配伴侣的存在和推广性周期（参考文献5审查）的进一步措施。氮剥夺脱阻抑交配Ste11的关键转录调节充当发育开关并促进È交配特定基因，包括信息素受体 和信息素产生的基因6,7的表达。信息素受体 参与激活受体偶联蛋白G-alpha和下游MAPK信号进一步增强Ste11转录活性8-10，从而增加交配伙伴之间的正反馈信息素的生产。信息素水平是通过调节细胞极性，卢家族GTP酶Cdc42的11的主组织者诱发不同的细胞极化状态至关重要。在暴露于低信息素浓度，活性的Cdc42被可视动态补丁探索细胞外围，并且没有细胞生长在此阶段观察到。增加信息素水平促进Cdc42活性的稳定到一个区和一个偏振投影的生长，称为SHMOO，这使伴侣细胞在接触。随后，两人单倍体交配伴侣融合形成二倍体合子。最近的研究表明日Ë存在一个新颖的肌动蛋白结构融合基本是由配合诱导formin FUS1 12组装的。这种融合焦点集中型-V的肌球蛋白依赖性过程并定位细胞壁降解机械，从而使细胞壁重塑，以允许无细胞裂解12质膜接触。在细胞 – 细胞融合，核所接触并进行核融合。受精卵（马尾巴的运动）的内部核心的一个突出动力蛋白依赖的背部和往复运动进而促进染色体同源13,14，随后是减数分裂的配对。最后，四款产品减数分裂的孢子时打包成单个孢子。
由于其复杂性和所涉及的许多步骤中，交配的详细监测已具有挑战性。两个显着的困难是，整个过程需要以及超过十五小时，使细胞难以同步。这些ðifficulties由单细胞显微镜方法规避。在这里，一般的协议，调查裂殖酵母的性周期呈现。用小的调整，此协议允许的所有不同的步骤的过程中，配合基因产物，交配型切换之后姐妹细胞非姐姐伙伴之间和之间细胞极化和配对，细胞 – 细胞融合的即感应的研究，和后融合的马尾巴的运动，减数分裂和孢子。此方法允许1）轻松地可视化荧光标记的蛋白随着时间的推移售前，售中和融合后; 2）鉴别相反交配型的细胞的行为;和3）测量和量化参数，如什穆，交配，融合或孢子形成的效率。
Protocol
Representative Results
Discussion
环境条件和养分有效性，特别是强烈地影响裂殖酵母生理学。氮饥饿是必要的承诺有性生殖，最初导致在有丝分裂细胞周期进展引人注目的变化（参考文献21和图2）。在从指数增长的人口脱氮，在分裂细胞体积迅速降低（ 图2C）和大部分细胞有丝分裂逮捕比进展新生成倍增长的细胞（参考文献21和图2D）的长度短。由于对面交配类型的细胞有?…
Disclosures
The authors have nothing to disclose.
Acknowledgements
AV是由EMBO长期博士后奖学金支持。研究马丁实验室由ERC启动赠款（GeometryCellCycle）和瑞士国家科学基金会资助（31003A_155944），以SGM资助。
Materials
| Glucose | Sigma-Aldrich | G8270-10KG | |
| KH2PO4 | Sigma-Aldrich | 1.05108.0050 | |
| NaCl | Sigma-Aldrich | 71381 | |
| MgSO4.7H2O | Sigma-Aldrich | 63140 | |
| CaCl2 | Sigma-Aldrich | 12095 | |
| Pantothenate | AppliChem | A2088,0025 | |
| Nicotinic Acid | AppliChem | A0963,0100 | |
| Inositol | AppliChem | A1716,0100 | |
| Biotin | AppliChem | A0967,0250 | |
| Boric Acid | Sigma-Aldrich | B6768-1KG | |
| MnSO4 | AppliChem | A1038,0250 | |
| ZnSO4.7H2O | Sigma-Aldrich | Z4750 | |
| FeCl2.6H2O | AppliChem | A3514,0250 | |
| Molybdenum oxide (VI) (MoO3) | Sigma-Aldrich | 69850 | |
| KI | AppliChem | A3872,0100 | |
| CuSO4.5H2O | AppliChem | A1034,0500 | |
| Citric Acid | AppliChem | A2344,0500 | |
| Agarose | Promega | V3125 | |
| (NH4)2SO4 | Merck | 1.01217.1000 | |
| L-Leucine | Sigma-Aldrich | L8000-100G | |
| Adenine Hemisulfat Salt, mini 99% | Sigma-Aldrich | A9126-100G | |
| Uracil | Sigma-Aldrich | U0750 | |
| Lanolin | Sigma-Aldrich | L7387 | |
| Vaseline | Reactolab | 92045-74-4 | |
| Paraffin | Reactolab | 7005600 |
References
- Mata, J., Bahler, J. Global roles of Ste11p, cell type, and pheromone in the control of gene expression during early sexual differentiation in fission yeast. Proc Natl Acad Sci U S A. 103 (42), 15517-15522 (2006).
- Xue-Franzen, Y., Kjaerulff, S., Holmberg, C., Wright, A., Nielsen, O. Genomewide identification of pheromone-targeted transcription in fission yeast. BMC Genomics. 7, 303 (2006).
- Klar, A. J. Lessons learned from studies of fission yeast mating-type switching and silencing. Annu Rev Genet. 41, 213-236 (2007).
- Beach, D. H., Klar, A. J. Rearrangements of the transposable mating-type cassettes of fission yeast. EMBO J. 3 (3), 603-610 (1984).
- Merlini, L., Dudin, O., Martin, S. G. Mate and fuse: how yeast cells do it. Open Biol. 3 (3), 130008 (2013).
- Mochizuki, N., Yamamoto, M. Reduction in the intracellular cAMP level triggers initiation of sexual development in fission yeast. Mol Gen Genet. 233 (1-2), 17-24 (1992).
- Sugimoto, A., Iino, Y., Maeda, T., Watanabe, Y., Yamamoto, M. Schizosaccharomyces pombe ste11+ encodes a transcription factor with an HMG motif that is a critical regulator of sexual development. Genes Dev. 5 (11), 1990-1999 (1991).
- Kjaerulff, S., Lautrup-Larsen, I., Truelsen, S., Pedersen, M., Nielsen, O. Constitutive activation of the fission yeast pheromone-responsive pathway induces ectopic meiosis and reveals ste11 as a mitogen-activated protein kinase target. Mol Cell Biol. 25 (5), 2045-2059 (2005).
- Obara, T., Nakafuku, M., Yamamoto, M., Kaziro, Y. Isolation and characterization of a gene encoding a G-protein alpha subunit from Schizosaccharomyces pombe: involvement in mating and sporulation pathways. Proc Natl Acad Sci U S A. 88 (13), 5877-5881 (1991).
- Toda, T., Shimanuki, M., Yanagida, M. Fission yeast genes that confer resistance to staurosporine encode an AP-1-like transcription factor and a protein kinase related to the mammalian ERK1/MAP2 and budding yeast FUS3 and KSS1 kinases. Genes Dev. 5 (1), 60-73 (1991).
- Bendezu, F. O., Martin, S. G. Cdc42 explores the cell periphery for mate selection in fission yeast. Curr Biol. 23 (1), 42-47 (2013).
- Dudin, O., et al. A formin-nucleated actin aster concentrates cell wall hydrolases for cell fusion in fission yeast. J Cell Biol. 208 (7), 897-911 (2015).
- Chikashige, Y., et al. Telomere-led premeiotic chromosome movement in fission yeast. Science. 264 (5156), 270-273 (1994).
- Bahler, J., et al. Heterologous modules for efficient and versatile PCR-based gene targeting in Schizosaccharomyces pombe. Yeast. 14 (10), 943-951 (1998).
- Egel, R., Willer, M., Kjaerulff, S., Davey, J., Nielsen, O. Assessment of pheromone production and response in fission yeast by a halo test of induced sporulation. Yeast. 10 (10), 1347-1354 (1994).
- Tran, P. T., Marsh, L., Doye, V., Inoue, S., Chang, F. A mechanism for nuclear positioning in fission yeast based on microtubule pushing. J Cell Biol. 153 (2), 397-411 (2001).
- Pedelacq, J. D., Cabantous, S., Tran, T., Terwilliger, T. C., Waldo, G. S. Engineering and characterization of a superfolder green fluorescent protein. Nat Biotechnol. 24 (1), 79-88 (2006).
- Kitamura, K., Shimoda, C. The Schizosaccharomyces pombe mam2 gene encodes a putative pheromone receptor which has a significant homology with the Saccharomyces cerevisiae Ste2 protein. EMBO J. 10 (12), 3743-3751 (1991).
- Tanaka, K., Davey, J., Imai, Y., Yamamoto, M. Schizosaccharomyces pombe map3+ encodes the putative M-factor receptor. Mol Cell Biol. 13 (1), 80-88 (1993).
- Motegi, F., Arai, R., Mabuchi, I. Identification of two type V myosins in fission yeast, one of which functions in polarized cell growth and moves rapidly in the cell. Mol Biol Cell. 12 (5), 1367-1380 (2001).
- Sajiki, K., Pluskal, T., Shimanuki, M., Yanagida, M. Metabolomic analysis of fission yeast at the onset of nitrogen starvation. Metabolites. 3 (4), 1118-1129 (2013).
- Miyawaki, A., Nagai, T., Mizuno, H. Mechanisms of protein fluorophore formation and engineering. Curr Opin Chem Biol. 7 (5), 557-562 (2003).
- Dyer, J. M., et al. Tracking shallow chemical gradients by actin-driven wandering of the polarization site. Curr Biol. 23 (1), 32-41 (2013).
- Beta, C., Bodenschatz, E. Microfluidic tools for quantitative studies of eukaryotic chemotaxis. Eur J Cell Biol. 90 (10), 811-816 (2011).
- Lee, S. S., et al. Quantitative and dynamic assay of single cell chemotaxis. Integr Biol (Camb). 4 (4), 381-390 (2012).
