Botany, Ahead of Print.
Indeterminate growth, as in the hyphae of the “Humongous Fungus” of Michigan, requires sustained nuclear migration and cell wall remodeling. In this study, we compare actin organization and patterns of nuclear positioning among four distantly related, indeterminate species of phylum Chytridiomycota: Cladochytrium replicatum Karling (Cladochytriaceae), Physocladia obscura Sparrow (Chytriomycetaceae, Chytridiales), Nowakowskiella sp. J. Schröt. (Nowakowskiellaceae), and Polychytrium aggregatum Ajello (Polychytriales). We combined light microscopy, nuclear staining with 4′,6-diamidino-2-phenylindole, and actin staining with rhodamine phalloidin to analyze actin distribution and nuclear migration during somatic growth in the four Chytridiomycota species. Actin formed plaques, filaments, cables, and perinuclear shells in patterns that varied across the four species. All four species initiated indeterminate growth by extending branching, anucleate rhizomycelium, <1 µm in diameter. Nuclei, some elongated as if migrating, first appear in intercalary segments that widened to diameters >1 µm. After mitosis, an intercalary swelling in C. replicatum became septate and a single, distal nucleus migrated tipwards to a new swelling. In Physocladia obscura, swellings were aseptate and multinucleate, and several nuclei migrated tipwards into a new swelling. Nuclei migrated tipwards from irregularly cylindrical filaments in Nowakowskiella sp., and in Polychytrium aggregatum, from regular, hypha-like filaments. Thus, distantly related lineages of zoosporic fungi deploy ancestral morphogenetic machinery in differing patterns that result in convergent, indeterminate growth.

中文翻译：

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肌动蛋白和细胞核的不同组织支撑了壶菌和迪卡利亚的不确定生长的演变

植物学，提前印刷。
如密歇根州“巨大真菌”的菌丝一样，不确定的生长需要持续的核迁移和细胞壁重塑。在这项研究中，我们比较了四个遥相关，不确定的门扇菌门的肌动蛋白组织和核定位模式：克氏梭状芽孢杆菌（Cladochytriaceae），暗sc Physocladia obscura麻雀（Chytriomycetaceae，Chytridiales）和Nowakowskiella sp。J.Schröt。（Nowakowskiellaceae）和Polychytrium aggregatum Ajello（Polychytriales）。我们结合光学显微镜，用4'，6-diamidino-2-phenylindole进行核染色和用若丹明鬼笔环肽进行肌动蛋白染色来分析四种梭菌属物种在体细胞生长过程中的肌动蛋白分布和核迁移。肌动蛋白形成的斑块，细丝，电缆，和核周壳的样式在这四个物种中有所不同。这四个物种均通过扩展分支，直径小于1 µm的无核根状菌丝体而开始不确定的生长。原子核首先延伸到直径> 1 µm的cal间节段，有些像迁移一样伸长。有丝分裂后，复制梭状芽孢杆菌的sw间肿胀逐渐分离，单个远端核向前端迁移至新的肿胀。在暗藏的Physocladia中，肿胀呈腹核状和多核，几个核向尖端迁移成新的肿胀。细胞核从Nowakowskiella sp。的不规则圆柱状细丝向前端迁移，在Polychytrium agregatum中从规则的菌丝状细丝向内迁移。因此，