Is Fasciola monospecies? : Cross experiments between Fasciola hepatica and F.gigantica

本研究的第一个目的是通过实验感染寻找对肝片吸虫和巨型吸虫易感的小实验动物。大鼠、沙鼠（Meriones unguiculatus）和大鼠样仓鼠（tcherskia triton）分别口服2 ~ 10个囊蚴，2 ~ 3个月后处死。检查肝实质和胆管中吸虫的存在、感染率和肝脏损伤情况。将获得的吸虫固定在70%乙醇中，用Carmin溶液染色，测量体长和体宽。肝螺旋体在3种动物中回收率高且成熟，巨型螺旋体在3种动物中回收率低且未成熟。这些结果表明，这三种动物不能同时充当两种片形吸虫的适宜宿主。以啮齿动物为实验对象，对双性肝炎单倍体（Fh）与孤雌二倍体（2n）或三倍体（3n）进行了杂交实验，并通过染色体和DNA序列分析对其第一代（F1）进行了遗传表征。在第一个实验中，将Fh和2n的单个囊蚴口服接种于大鼠样仓鼠。形态学观察证实，从宿主体内恢复的2n型吸虫与Fh型吸虫结合。由2n吸虫产生的F1是异源多倍体（三倍体），这表明Fh和2n是不同的物种。第二个实验，分别接种Fh和3n各10只囊蚴于Wistar大鼠。从大鼠身上回收的3n个被证实与Fh吸虫结合的吸虫被提供给F1的生产。遗传观察表明，F1为四倍体，生殖细胞中有10条单价染色体和10条三价染色体。此外，F1有异常的精子发生。这些结果表明，肝单胞菌和疏原性三倍体是不同的种。F1四倍体不育。以山羊为寄主，进行了Fh与Fg、Fg与孤雌二倍体（2n）或三倍体（3n）的杂交实验。不幸的是，感染了Fh和Fg的山羊在吸虫成熟时已经死亡，因此无法获得两个物种之间的F1吸虫。而Fg与孤雌倍体之间的F1s到实验结束时还没有得到。但这些结果表明，肝吸虫、巨吸虫和孤雌吸虫是不同的种。少

The first purpose of the study is to find small experimental animals susceptible to Fasciola hepatica and F.gigantica through experimental infections. Rats, gerbils (Meriones unguiculatus), and the rat-like hamster, Tscherskia triton were orally inoculated with 2 to 10 metacercariae of the two species, and then sacrificed after 2 to 3 months. The animals were checked for the presence of flukes in the liver parenchyma and bile duct, infection rate and damage of the liver. The flukes obtained were fixed in 70% ethanol, stained with Carmin solution, and measured on the body length and width. F.hepatica had high recovery rate and matured in the three animal species, while F.gigantica had low rate and did not matured in all the hosts. These findings showed that these three animals could not play the role of suitable hosts of both Fasciola species.Cross experiments between bisexual F.hepatica (Fh) and parthenogenic diploid (2n) or triploid (3n) were carried out using rodent hosts, and the fi … More rst filial generations (F1) were genetically characterized by analyzes of chromosomes and DNA sequences. In the first experiments, single metacercariae of both Fh and 2n were orally inoculated to the rat-like hamster, Tscherskia triton. A 2n fluke recovered from the host was confirmed to conjugate with a Fh fluke by morphological observation. F1 produced from the 2n fluke was allopolyploid (triploid) and this suggested that Fh and 2n were different species each other. In the second experiments, 10 metacercariae each of Fh and 3n were inoculated to Wistar rats. The 3n flukes recovered from the rats and confirmed to conjugate with a Fh fluke were provided for production of F1. Genetic observation showed that the F1 was a tetraploid and had 10 univalent chromosomes and 10 trivalent chromosomes in reproductive cells. Furthermore, the F1 had abnormal spermatogenesis. These findings suggested that F.hepatica and parhtenogenic triploid were different species each other. The F1 tetraploid was sterile.Cross experiments between Fh and Fg, and Fg and parthenogenic diploid (2n) or triploid (3n) were carried out using goat hosts. Unfortunately, the goat infected with both Fh and Fg was dead by the time the flukes have matured and therefore the F1 flukes between the two species could not be obtained. While the F1s between Fg and the parthenogenic plolpoids have not been obtained by the time the experimental period expired. However, these findings suggest that F.hepatica, F.gigantica and parthenogenic Fasciola sp. are different species each other. Less