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大片吸虫易感的小型实验动物。对大鼠、长爪沙鼠和似鼠仓鼠Tscherskia Triton经口接种2~10个囊虫，2~3个月后处死。检查动物肝实质和胆管中是否有吸虫，感染率和肝脏损伤。获得的吸虫用70%乙醇固定，卡明溶液染色，测量体长和体宽。肝片吸虫回收率高，在三种动物体内成熟；大片吸虫回收率低，并不是所有寄主都成熟。利用鼠类寄主进行了两性肝片吸虫(Fh)与孤雌生殖二倍体(2n)和三倍体(3n)的杂交试验，并用FI-…染色体和DNA序列分析表明，较多的第一代(F1)具有遗传特征。在第一个实验中，将Fh和2n的单个囊虫口服接种到类鼠仓鼠Tscherskia Triton上。经形态观察证实，从寄主体内回收的一株2n吸虫与一只FH吸虫结合。从2n吸虫产生的F1是异源多倍体(三倍体)，这表明Fh和2n是不同的种。在第二个实验中，将Fh和3n各10个囊虫接种给Wistar大鼠。从大鼠体内回收的3n吸虫被证实与一只FH吸虫结合，用于生产F1。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代存在精子发生异常。这些结果表明，肝片吸虫和侧生三倍体彼此是不同的种。FH与FG杂交，FG与孤雌生殖二倍体(2n)或三倍体(3n)杂交。不幸的是，同时感染FH和FG的山羊在吸虫成熟时已经死亡，因此无法获得这两个物种之间的F1吸虫。而FG和孤雌生殖倍体之间的F1在实验期结束时仍未获得。然而，这些发现表明，肝片吸虫、巨型肝片吸虫和孤雌生殖片形吸虫sp.是彼此不同的物种。较少

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