The Diplomonad Fish Parasite Spironucleus vortens Produces Hydrogen

ABSTRACT. The diplomonad fish parasite Spironucleus vortens causes major problems in aquaculture of ornamental fish, resulting in severe economic losses in the fish farming industry. The strain of S. vortens studied here was isolated from an angelfish and grown in Keister's modified TY‐I‐S33 medium. A membrane‐inlet mass spectrometer was employed to monitor, in a closed system, O₂, CO₂, and H₂. When introduced into air‐saturated buffer, S. vortens rapidly consumed O₂ at the average rate of 62±4 nmol/min/10⁷ cells and CO₂ was produced at 75±11 nmol/min/10⁷ cells. Hydrogen production began under microaerophilic conditions ([O₂]=33.±15 μM) at a rate of 77±7 nmol/min/10⁷ cells. Hydrogen production was inhibited by 62% immediately after adding 150 μM KCN to the reaction vessel, and by 50% at 0.24 μM CO, suggesting that an Fe‐only hydrogenase is responsible for H₂ production. Metronidazole (1 mM) inhibited H₂ production by 50%, while CO₂ production was not affected. This suggests that metronidazole may be reduced by an enzyme of the H₂ pathway, thus competing for electrons with H⁺.     

Polymorphic microsatellite DNA markers for the Florida manatee (Trichechus manatus latirostris)

Florida manatees (Trichechus manatus latirostris) are marine mammals that inhabit the coastal waters and rivers of the southeastern USA, primarily Florida. Previous studies have shown that Florida manatees have low mitochondrial DNA variability, suggesting that nuclear DNA loci are necessary for discriminatory analyses. Here we report 10 polymorphic microsatellite loci with an average of 4.2 alleles per locus, and average heterozygosity of 50.1%. These loci have been developed for use in population studies, parentage assignment, and individual identification.