The @entity3968 ( @entity3968 ) is the definitive host for at least three named species of Sarcocystis: Sarcocystis falcatula, Sarcocystis neurona and Sarcocystis speeri. The South American opossums (Didelphis albiventris, Didelphis marsupialis and Didelphis aurita) are definitive hosts for S. falcatula and S. lindsayi. The sporocysts of these Sarcocystis species are similar morphologically. They are also not easily distinguished genetically because of the difficulties of DNA extraction from sporocysts and availability of distinguishing genetic markers. Some of these species can be distinguished by bioassay; S. neurona and S. speeri are infective to @entity60 gene knockout (KO) @entity19 , but not to @entity5798 ( @entity5798 ); whereas S. falcatula and S. lindsayi are infective to @entity5798 but not to KO @entity19 . The natural intermediate host of S. speeri is unknown. In the present study, development of sarcocysts of S. speeri in the KO @entity19 is described. Sarcocysts were first seen at 12 days post-inoculation (p.i.), and they became macroscopic (up to 4 mm long) by 25 days p.i. The structure of the sarcocyst wall did not change from the time bradyzoites had formed at 50-220 days p.i. Sarcocysts contained unique villar protrusions, 'type 38'. The polymerase chain reaction amplifications and sequences analysis of three nuclear loci (18S rRNA, 28S rRNA and ITS1) and two mitochondrial loci ( @entity16538 and @entity16886 ) of S. speeri isolate from an Argentinean opossum (D. albiventris) confirmed its membership among species of Sarcocystis and indicated an especially close relationship to another parasite in this genus that employs opossums as its definitive host, S. neurona. These results should be useful in finding natural intermediate host of S. speeri.

Molecular characterization and development of Sarcocystis speeri sarcocysts in XXXX gene knockout @entity19 .

@entity16538 :: ('17708(Tax:10090)', 'Gene') :: ['cox1'] @entity16886 :: ('17711(Tax:10090)', 'Gene') :: ['cytb'] @entity19 :: ('10090', 'Species') :: ['mice'] @entity3968 :: ('9267', 'Species') :: ['North American opossum', 'Didelphis virginiana'] @entity60 :: ('15978(Tax:10090)', 'Gene') :: ['gamma interferon'] @entity5798 :: ('13146', 'Species') :: ['budgerigars', 'Melopsittacus undulatus']
@entity60 :: (15978(Tax:10090),Gene) :: ['gamma interferon']
