Riquelme M, Reynaga-Peña C G, Gierz G, Bartnicki-García S
Department of Plant Pathology, University of California, Riverside, California, 92521-0122, USA.
Fungal Genet Biol. 1998 Jun-Jul;24(1-2):101-9. doi: 10.1006/fgbi.1998.1074.
We used high-resolution video microscopy and image analysis to map the trajectory of the Spitzenkörper in growing hyphae of Neurospora crassa and to correlate it with growth directionality. The Spitzenkörper followed a tortuous trajectory produced by a dominant forward motion accompanied by frequent, transverse oscillations. In hyphae with a fixed growth direction, the regression line of the Spitzenkörper trajectory corresponded to the longitudinal axis of the hypha. A permanent change in growth direction, i.e., the establishment of a new growth axis, was correlated with a sustained shift in Spitzenkörper trajectory away from the existing cell axis. In meandering hyphae, changes in growth directionality occurred somewhat erratically but there was a strong compensatory tendency reversing directional shifts and maintaining an overall fixed direction of growth. Although external factors greatly affect hyphal growth direction (tropisms), they are probably not the primary determinants of growth directionality. Inhibitors of microtubules, but not of actin microfilaments, caused hyphae to lose their growth directionality-providing support for the idea that Spitzenkörper trajectory is determined internally by a growing scaffolding of cytoplasmic microtubules. The meandering morphology of N. crassa hyphae was duplicated by computer simulation in support of the idea that hyphal morphogenesis is controlled by the position of the Spitzenkörper functioning as a vesicle supply center.
我们使用高分辨率视频显微镜和图像分析技术来绘制粗糙脉孢菌生长菌丝中 Spitzenkörper 的轨迹，并将其与生长方向性相关联。Spitzenkörper 遵循一条由主导向前运动以及频繁横向振荡产生的曲折轨迹。在生长方向固定的菌丝中，Spitzenkörper 轨迹的回归线与菌丝的纵轴相对应。生长方向的永久性变化，即新生长轴的建立，则与 Spitzenkörper 轨迹持续偏离现有细胞轴相关。在蜿蜒的菌丝中，生长方向性的变化有些不稳定，但存在强烈的补偿趋势，可逆转方向偏移并维持总体固定的生长方向。尽管外部因素极大地影响菌丝的生长方向（向性），但它们可能并非生长方向性的主要决定因素。微管抑制剂而非肌动蛋白微丝抑制剂会导致菌丝失去其生长方向性，这为 Spitzenkörper 轨迹由细胞质微管不断生长的支架在内部决定这一观点提供了支持。粗糙脉孢菌菌丝的蜿蜒形态通过计算机模拟得以重现，以支持菌丝形态发生由作为囊泡供应中心的 Spitzenkörper 的位置所控制这一观点。
