ABSTRACT The advantage of filamentous growth to the fungal lifestyle is so great that it arose multiple times. Most zoosporic fungi from phylum Chytridiomycota exhibit a monocentric thallus form consisting of anucleate filamentous rhizoids that anchor reproductive sporangia to substrata and absorb nutrients. Actin function during polarized growth and cytokinesis is well documented across eukaryotes, but its role in sculpting nonhyphal, nonyeast fungal cells is unknown. We sought to provide a basis for comparing actin organization among major fungal lineages and to investigate the effects of actin disruption on morphogenesis in a monocentric thallus. Using fluorescence microscopy, we observed fixed, rhodamine phalloidin–stained actin in chemically fixed Chytriomyces hyalinus, exemplifying monocentric thallus development within the diverse, zoosporic phylum Chytridiomycota. We also compared rhizoid lengths and rhizoid branching of thalli incubated with the actin inhibitor latrunculin B to determine the effects of actin disruption on morphology. Actin was concentrated at the tips of growing rhizoids. Actin cables typically formed cortical, parallel arrays in hyphae, but in mature sporangia they were concentrated in a funnel-shaped array in the central region. Thalli treated with latrunculin B had shorter rhizoids with fewer branches than controls. In both hyphae and monocentric thalli, actin localization coincides with active, polarized growth and cytokinesis. Specific actin localization patterns are largely shared between monocentric species but differ significantly from patterns observed in hyphae. Actin integrity is critical for sustaining filamentous growth in all fungi.

中文翻译：

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肌动蛋白在游动孢子真菌透明乳糜泻中引导丝状假根的生长和形态发生

摘要 丝状生长对真菌生活方式的优势是如此之大，以至于多次出现。大多数来自壶菌门的游动孢子真菌表现出单中心菌体形式，由无核丝状假根组成，将繁殖孢子囊固定在基质上并吸收营养。极化生长和胞质分裂过程中的肌动蛋白功能在真核生物中有很好的记录，但其在雕刻非菌丝、非酵母真菌细胞中的作用尚不清楚。我们试图为比较主要真菌谱系中的肌动蛋白组织提供基础，并研究肌动蛋白破坏对单中心菌体形态发生的影响。使用荧光显微镜，我们观察到化学固定的透明乳球菌中固定的、罗丹明鬼笔环肽染色的肌动蛋白，举例说明了不同种类中的单中心菌体发育，游动孢子门壶菌门。我们还比较了用肌动蛋白抑制剂 latrunculin B 孵育的菌体的根状茎长度和根状茎分枝，以确定肌动蛋白破坏对形态的影响。肌动蛋白集中在生长的假根的尖端。肌动蛋白索通常在菌丝中形成皮质平行阵列，但在成熟的孢子囊中，它们集中在中央区域的漏斗形阵列中。与对照相比，用 latrunculin B 处理的菌体具有更短的假根和更少的分枝。在菌丝和单中心菌体中，肌动蛋白定位与活跃的极化生长和胞质分裂相一致。特定的肌动蛋白定位模式主要在单中心物种之间共享，但与在菌丝中观察到的模式显着不同。肌动蛋白的完整性对于维持所有真菌的丝状生长至关重要。