Mendlovic Fela, Carrillo-Farga Joaquín, Torres José, Laclette Juan Pedro, Flisser Ana
Departamento de Microbiología y Parasitología, Facultad de Medicina, UNAM, Av. Universidad 3000, Universidad Nacional Autónoma de México, México DF 04510, México.
J Parasitol. 2006 Aug;92(4):789-95. doi: 10.1645/GE-724R1.1.
Taenia solium, a cestode that causes neurocysticercosis and taeniasis in humans, has a complex life cycle. The adult tapeworm develops in the intestine of human beings and is also responsible for neurocysticercosis, which is caused by the metacestode or cysticercus that develops in the brain. Recently, we have cloned the coding region for T. solium calreticulin (TsCRT) as a functional Ca(2+)-binding protein. Calreticulin is a ubiquitous protein involved in cellular Ca2+ homeostasis and protein folding. These important functions affect several aspects of cell physiology. To explore the expression of TsCRT during the T. solium life cycle, we used a specific polyclonal antibody raised against recombinant TsCRT to localize this protein by immunolabeling techniques. In sections of cysticerci obtained from swine muscle, as well as of adult tapeworms obtained after infection of hamsters with cysticerci, TsCRT was preferentially localized in tegumentary and muscle cytons of the suckers and rostellum. In mature proglottids obtained from infected humans, positive staining was observed in spermatogonia, ovogonia, uterine epithelium, and cells of the vas deferens. In the gravid uterus, the morula and early stage embryos were highly positive to TsCRT. However, expression diminished as embryonic development progressed and was absent in fully developed oncospheres that were surrounded by an embryophore. A similar down regulation was observed during spermatogenesis. Although early spermatocytes showed a high expression of TsCRT, mature spermatozoa present in the vas deferens were completely negative. These data indicate that calreticulin expression is spatially and temporally regulated during development of T. solium, especially during germ cell development and embryogenesis. In addition, these original images illustrate, for the first time, these processes at a histological level.
猪带绦虫是一种能在人类中引起神经囊尾蚴病和猪带绦虫病的绦虫，其生命周期复杂。成虫绦虫在人类肠道中发育，也是神经囊尾蚴病的病因，该病由在大脑中发育的中绦期幼虫或囊尾蚴引起。最近，我们克隆了猪带绦虫钙网蛋白（TsCRT）的编码区，它是一种功能性钙结合蛋白。钙网蛋白是一种普遍存在的蛋白质，参与细胞内钙稳态和蛋白质折叠。这些重要功能影响细胞生理学的多个方面。为了探究猪带绦虫生命周期中TsCRT的表达情况，我们使用针对重组TsCRT产生的特异性多克隆抗体，通过免疫标记技术对该蛋白进行定位。在从猪肌肉中获取的囊尾蚴切片以及用囊尾蚴感染仓鼠后获得的成虫绦虫切片中，TsCRT优先定位在吸盘和头节的体表和肌肉细胞体中。在从受感染人类获取的成熟节片中，精原细胞、卵原细胞、子宫上皮和输精管细胞中观察到阳性染色。在妊娠子宫中，桑椹胚和早期胚胎对TsCRT呈高度阳性。然而，随着胚胎发育的进行，表达减弱，在被胚膜包围的完全发育的六钩蚴中则不存在表达。在精子发生过程中也观察到类似的下调情况。虽然早期精母细胞显示出TsCRT的高表达，但输精管中的成熟精子则完全呈阴性。这些数据表明，钙网蛋白的表达在猪带绦虫发育过程中受到时空调节，尤其是在生殖细胞发育和胚胎发生过程中。此外，这些原始图像首次在组织学水平上展示了这些过程。
