A Bge cell co-culture system, previously shown to support the in
vitro production of daughter sporocysts from mother
sporocysts of Schistosoma mansoni and S. japonicum, has
proven capable of supporting the in vitro development of
intramolluscan stages of the deer liver fluke, Fascioloides magna.
Miracidia commenced transforming within 4 h of
incubation with Bge cells, and had completely shed their epidermal plates
within 18–24 h. Redial stages were visible inside
in vitro-transformed mother sporocysts after 12–16 days
of co-culture with Bge cells, and emerged as fully-developed
larvae starting at 14–20 days post-cultivation. Rediae survived over
60 days of in vitro culture, and reached a maximum
size of 150–170 μm. Although particulate material was visible
in their cecae, rediae were not observed to actively feed on
Bge cells. Bge cells did not attach to or encapsulate larval stages at
any time throughout the incubation period. Unlike
Schistosoma spp., in which a high percentage of miracidia spontaneously
shed their ciliated epidermal plates and
transformed into mother sporocysts in Chernin's balanced saline solution
(CBSS), transformation of F. magna was
dependent on Bge cell products. Less than 5% of F. magna miracidia
transformed spontaneously in either CBSS or Bge
medium with 10% fetal bovine serum (complete or C-Bge). However, incubation
of miracidia in either Bge cell-conditioned
C-Bge medium or a greater than 30 kDa fraction concentrated from conditioned
CBSS increased transformation
rates to 67 and 83%, respectively. This secretory Bge cell factor(s) appeared
to be protein in nature since its activity
was completely abrogated by heat or proteinase K treatments. Overall, these
results demonstrate that Bge cells are required
for stimulating in vitro miracidial transformation and supporting
early larval development of a fasciolid trematode under
culture conditions. This is the first report of in vitro development
of rediae from miracidia for a digenetic trematode.
Purification and characterization of mitochondrial thioredoxin reductase enzyme from rainbow trout (Oncorhynchus mykiss) liver and investigation of the in vitro effects of some metal ions on the enzyme