In vitro propagation followed by PCR, and a PCR-based method capable of the direct detection of Blastocystis in faeces were utilized to detect Blastocystis from various hosts in Australia, including primates and their handlers from the Perth Zoo. In addition, Blastocystis isolates from dogs and humans living in a localized endemic community in Thailand were also characterized genetically. PCR-based detection directly from faeces was shown to be more sensitive compared with in vitro culture for the detection of Blastocystis. Moreover, phylogenetic analysis of Blastocystis isolates amplified utilizing in vitro techniques prior to PCR revealed that this method favoured the preferential amplification of Blastocystis subtype 5 over subtype 1. This study is the first to provide molecular-based evidence supporting the zoonotic potential of Blastocystis in dogs, possums and primates in a natural setting.

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BACKGROUNDTesticular germ cell tumours (TGCT) are thought to originate from fetal germ cells that fail to differentiate normally, but no animal model for these events has been described. We evaluated the marmoset (Callithrix jacchus) as a model by comparing perinatal germ cell differentiation with that in humans.METHODSImmunohistochemical profiling was used to investigate germ cell differentiation (OCT4, NANOG, AP-2γ, MAGE-A4, VASA, NANOS-1) and proliferation (Ki67) in fetal and neonatal marmoset testes in comparison with the human and, to a lesser extent, the rat.RESULTSIn marmosets and humans, differentiation of gonocytes into spermatogonia is associated with the gradual loss of pluripotency markers such as OCT4 and NANOG, and the expression of germ cell-specific proteins such as VASA. This differentiation occurs asynchronously within individual cords during fetal and early postnatal life. This contrasts with rapid and synchronous germ cell differentiation within and between cords in the rat. Similarly, germ cell proliferation in the marmoset and human occurs throughout perinatal life, in contrast to rats in which proliferation ceases during this period.CONCLUSIONSThe marmoset provides a good model for normal human germ cell differentiation and proliferation. The perinatal marmoset may be a useful model in which to establish factors that lead to failure of normal germ cell differentiation and the origins of TGCT.

BackgroundCertain phthalates can impair Leydig cell distribution and steroidogenesis in the fetal rat in utero, but it is unknown whether similar effects might occur in the human.ObjectivesOur aim in this study was to investigate the effects of di(n-butyl) phthalate (DBP), or its metabolite monobutyl phthalate (MBP), on testosterone production and Leydig cell aggregation (LCA) in fetal testis explants from the rat and human, and to compare the results with in vivo findings for DBP-exposed rats. We also wanted to determine if DBP/MBP affects testosterone production in vivo in the neonatal male marmoset.MethodsFetal testis explants obtained from the rat [gestation day (GD)19.5] and from the human (15–19 weeks of gestation) were cultured for 24–48 hr with or without human chorionic gonadotropin (hCG) or 22R-hydroxycholesterol (22R-OH), and with or without DBP/MBP. Pregnant rats and neonatal male marmosets were dosed with 500 mg/kg/day DBP or MBP.ResultsExposure of rats in utero to DBP (500 mg/kg/day) for 48 hr before GD21.5 induced major suppression of intratesticular testosterone levels and cytochrome P450 side chain cleavage enzyme (P450scc) expression; this short-term treatment induced LCA, but was less marked than longer term (GD13.5–20.5) DBP treatment. In vitro, MBP (10−3 M) did not affect basal or 22R-OH-stimulated testosterone production by fetal rat testis explants but slightly attenuated hCG-stimulated steroidogenesis; MBP induced minor LCA in vitro. None of these parameters were affected in human fetal testis explants cultured with 10−3 M MBP for up to 48 hr. Because the in vivo effects of DBP/MBP were not reproduced in vitro in the rat, the absence of MBP effects in vitro on fetal human testes is inconclusive. In newborn (Day 2–7) marmosets, administration of a single dose of 500 mg/kg MBP significantly (p = 0.019) suppressed blood testosterone levels 5 hr later. Similar treatment of newborn co-twin male marmosets for 14 days resulted in increased Leydig cell volume per testis (p = 0.011), compared with co-twin controls; this is consistent with MBP-induced inhibition of steroidogenesis followed by compensatory Leydig cell hyperplasia/hypertrophy.ConclusionsThese findings suggest that MBP/DBP suppresses steroidogenesis by fetal-type Leydig cells in primates as in rodents, but this cannot be studied in vitro.