Abstract：
BACKGROUND: Tapeworms are parasitic flatworms that independently evolved a segmented body plan, historically confounding comparisons with other animals. Anteroposterior (AP) patterning in free-living flatworms and in tapeworm larvae is associated with canonical Wnt signaling and positional control genes (PCGs) are expressed by their musculature in regionalized domains along the AP axis. Here, we extend investigations of PCG expression to the adult of the mouse bile-duct tapeworm Hymenolepis microstoma, focusing on the growth zone of the neck region and the initial establishment of segmental patterning.
RESULTS: We show that the adult musculature includes new, segmental elements that first appear in the neck and that the spatial patterns of Wnt factors are consistent with expression by muscle cells. Wnt factor expression is highly regionalized and becomes AP-polarized in segments, marking them with axes in agreement with the polarity of the main body axis, while the transition between the neck and strobila is specifically demarcated by the expression domain of a Wnt11 paralog.
CONCLUSIONS: We suggest that segmentation could originate in the muscular system and participate in patterning the AP axis through regional and polarized expression of PCGs, akin to the gene regulatory networks employed by free-living flatworms and other animals.
RESULTS: We show that the adult musculature includes new, segmental elements that first appear in the neck and that the spatial patterns of Wnt factors are consistent with expression by muscle cells. Wnt factor expression is highly regionalized and becomes AP-polarized in segments, marking them with axes in agreement with the polarity of the main body axis, while the transition between the neck and strobila is specifically demarcated by the expression domain of a Wnt11 paralog.
CONCLUSIONS: We suggest that segmentation could originate in the muscular system and participate in patterning the AP axis through regional and polarized expression of PCGs, akin to the gene regulatory networks employed by free-living flatworms and other animals.
摘要：
背景：丝虫是寄生的扁虫，它们独立进化出分段的身体计划，历史上与其他动物的混淆比较。自由生活的扁虫和the虫幼虫中的反向（AP）模式与规范的Wnt信号有关，位置控制基因（PCG）由其肌肉组织在沿AP轴的区域域中表达。这里,我们将PCG表达的研究扩展到小鼠胆管tape虫的成虫，关注颈部区域的生长带和节段模式的初步建立。
结果：我们表明，成人肌肉组织包括新的，首先出现在颈部的节段元件，并且Wnt因子的空间模式与肌肉细胞的表达一致。Wnt因子表达高度区域化，并在片段中变成AP极化，用与主体轴的极性一致的轴标记它们，而颈部和strobila之间的过渡由Wnt11模拟物的表达域具体划分。
结论：我们建议分割可能起源于肌肉系统，并通过PCGs的区域和极化表达参与AP轴的图案化，类似于自由生活的扁虫和其他动物所采用的基因调控网络。
结果：我们表明，成人肌肉组织包括新的，首先出现在颈部的节段元件，并且Wnt因子的空间模式与肌肉细胞的表达一致。Wnt因子表达高度区域化，并在片段中变成AP极化，用与主体轴的极性一致的轴标记它们，而颈部和strobila之间的过渡由Wnt11模拟物的表达域具体划分。
结论：我们建议分割可能起源于肌肉系统，并通过PCGs的区域和极化表达参与AP轴的图案化，类似于自由生活的扁虫和其他动物所采用的基因调控网络。
