High prevalence of pathogenic Leptospira in wild and domesticated animals in an endemic area of China.

OBJECTIVE: To assess the prevalence of Leptospira detected in wildlife and domesticated animals in Jiangxi Province, China, in. METHODS: Urine samples from 28 buffaloes and kidney samples from 50 pigs, 50 dogs and 38 rats were collected from Fuliang and Shangrao County, Jiangxi Province, China, in October 2009. Polymerase chain reaction(PCR)and culture analyses were used to detect Leptospira. The cultured isolates were typed using the microscopic agglutination test(MAT). RESULTS: The results showed that rats potentially serve as the main reservoir of leptospiral infection, followed by dogs. Although 16% of rats (6/38) were positive using culture analysis, PCR analysis using the diagnostic primers G1/G2 and B64I/B64II or lipL32 showed identification as 50% and 24%, respectively, of the rat samples as positive for the presence of leptospiral DNA. CONCLUSIONS: PCR-based detection of leptospiral DNA in infected kidney tissues of reservoirs is more efficient when using G1/G2 primers than lipL32 primers. However, the latter primers have a potential application for detection in urine samples. The alarmingly high prevalence of leptospiral DNA in the wild rat population near human habitation underscores the utility of routine Leptospira surveillance, preferably using PCR methods, which are more sensitive than traditional culture-based methods.

Germ cell sex prior to meiosis in the rainbow trout

Germ cells make two major decisions when they move from an indeterminate state to their final stage of gamete production. One decision is sexual commitment for sperm or egg production, and the other is to maintain mitotic division or entry into meiosis. It is unclear whether the two decisions are made as a single event or separate events, because there has been no evidence for the presence of germ cell sex prior to meiosis. Here we report direct evidence in the fish rainbow trout that gonia have distinct sexuality. We show that dazl expression occurs in both male and female gonia but exhibits differential intracellular distribution. More strikingly, we show that boule is highly expressed in male gonia but absent in female gonia. Therefore, mitotic gonia possess sex, sperm/egg decision and mitosis/meiosis decision are two independent events, and sperm/egg decision precedes mitosis/meiosis decision in rainbow trout, making this organism a unique vertebrate model for mechanistic understanding of germ cell sex differentiation and relationship between the two decisions.