EFFECTS OF VARYING CONCENTRATIONS OF THE CRUDE AQUEOUS AND ETHANOLIC

This study evaluated, using replicated laboratory bioassays, the toxicities of the crude aqueous and ethanolic extracts of Dalbergia sissoo Roxb. 1832 (family Leguminosae) fruits, leaves, roots and stem bark against egg masses of Biomphalaria pfeifferi (Krauss, 1848), the snail intermediate host of Schistosoma mansoni (Sambon, 1907) in Nigeria. Viable 0-24 hr-old embryonated egg masses were separately exposed to five different concentrations (7.81-2000 mg/l) of extracts for 24 hrs, washed in dechlorinated tap water and incubated at room temperature for a maximum of 4 weeks. The LC50 and LC90 values of test extracts for egg masses were calculated by probit analysis. The activities of the tested extracts were concentration-dependent. However, only the ethanolic extract of the fruits demonstrated significant activity (24 hr-LC90 value < 100 mg/l: 89.29 mg/l). Mortalities of eggs were manifested at the gastrula/exogastrula and or the prehatch snail stage of development. The percentage of dead embryos at the prehatch snail stage decreased while the deaths of embryos at the gastrula/exogastrula stage increased, with increasing concentration of extract. Lethality of the ethanolic extract of D. sissoo fruits to embryonated egg masses of B. pfeifferi is an added advantage to its potential development for use as a plant molluscicide, as the overall efficacy of a molluscicide is greatly enhanced if it also shows significant toxicity towards snail eggs

Assessment and Characterization of Ca2+ - ATPase expression in selected isolates and clones of Plasmodium Falciparum

Ca2+-ATPase expression in 15 selected isolates from malaria patients at the University College Hospital (UCH) Ibadan and two cloned strains (W2-chloroquine resistant, D6-chloroquine sensitive) of P. Falciparum was assessed using spectrophotometric assay method. The kinetics of activity of Ca2+ - ATPase in three isolates (NCP 14, NCP5, NCP1) and two clones (W2, D6) also assessed. 12% SDS – PAGE analysis of total proteins in one isolate (NCP14) and two clones (W2, D6) was also investigated. All the selected isolates and the two cloned strains exhibited measurable Ca2+-ATPase activity. The Ca2+ - ATPase activity in cloned strain D6 (6.50 ± 0.74μmolPi/min/mg protein) was higher than in cloned strain W2 (3.93 ± 0.61μmolPi/min/mg protein. The Ca2+-ATPase activity in isolates from malaria patients varied widely (1.95 ± 0.74 – 21.56 ±1.43μmolPi/min/mg protein). The kinetic constants obtained for the two cloned strains showed that clone W2 had a higher Vmax (Vmax = 363μmolPi/min/mg protein) than clone D6 (Vmax = 74μmolPi/min/mg protein). All the isolates and the two cloned strains showed similar affinity for ATP (Km ~ 10mM). Scan of SDS-PAGE gel of total proteins in the isolate and cloned strains showed the presence of oligopeptide bands of molecular weights range of 148-176 KDa; 116-123 KDa respectively. These suggest the presence of predicted polypeptide of Ca2+ - ATPase nature of molecular weight estimate of 139 KDa. The study agrees with previous findings that Ca2+-ATPase is functionally expressed in P.falciparum, The study also indicates that Ca2+ - ATPase functional expression may vary with isolate or clone but the ATP binding mechanism to the enzyme is similar in all isolates and clones of P.falciparum. The study further suggests a possible association between acquisition of chloroquine resistance and Ca2+- ATPase functional expression in P.falciparum