Citotoxicidade de plantas com indicativo etnográfico para a desinfecção de água

A água para o consumo humano e animal é um patrimônio cada vez mais escasso que é necessário preservar. O processo de desinfecção utilizado atualmente tem como base desinfetantes clorados, que em combinação com resíduos orgânicos, resultam em trihalometanos (potencialmente oncogênicos). A proposta deste trabalho foi avaliar a citotoxicidade de cinco extratos de plantas, capazes de promover desinfecção da água, frente a seis linhagens celulares, a saber: Vero (ATCC CCl81) African green monkey cells; MDBK (ATCC CCL 24) Martin Darby Bonne Kidney cells; MDCK (ATCC CCL 34) Canis familiaris kidney cells; CRFK (ATCC CCL 94) Felix catus kidney cells; PK 15 (ATCC CCL 33) Sus scrofa kidney cells; RK13 (ATCC CCL 37) Orytolagus cuniculus Kidney cells, e avaliar cultivos celulares mais sensíveis para o teste de toxicidade de extratos de plantas. Destes extratos, o mais tóxico foi o de Erva de Formigueiro (Chenopodium álbum) diante de todas as células testadas. O extrato de chapéu de couro (Sagittaria montevidensis) foi medianamente tóxico e os demais baleeira (Cordia curassavica), folha da fortuna (Bryophyllum pinnatum [Kurz]) e sete sangrias (Cuphea carthagenensis [Jacq.] J.F. Macbride) foram os menos tóxicos. Este resultado foi estatisticamente significativo (p=0,99), quando se comparou o extrato das plantas frente às concentrações e às células estudadas. Entre as células utilizadas, as mais sensíveis foram a VERO (rim de macaco) e a CRFK (rim de gato) quando comparadas com as demais foram (MDBK, MDCK, PK 15, RK 13), com diferença significativa (p=0,99). Conclui-se que há necessidade de serem avaliados os extratos vegetais quanto a toxicidade, antes do emprego como recursos de saúde, e que algumas células são mais eficazes que outras na detecção de efeito citopatogênico.

Intermolecular homologous recombination between transfected sequences in mammalian cells is primarily nonconservative.

Intermolecular recombination in mammalian cells was studied by coinfecting African green monkey cells in culture with two shuttle vector plasmids, each carrying an incomplete but overlapping portion of the gene for neomycin resistance. The region of homology between the two plasmids was about 0.6 kilobases. Recombination between the homology regions could reconstruct the neomycin resistance gene, which was monitored by analysis of progeny plasmids in bacteria. The individual plasmids carried additional markers which, in combination with restriction analysis, allowed the determination of the frequency of formation of the heterodimeric plasmid which would be formed in a conservative recombination reaction between the homologous sequences. Reconstruction of the neomycin resistance gene was readily observed, but only 1 to 2% of the neomycin resistance plasmids had the structure of the conservative heterodimer. Treatment of the plasmids which enhanced the frequency of the neomycin resistance gene reconstruction reaction did not significantly increase the relative frequency of conservative product plasmids. The results support nonconservative models for recombination of these sequences.

Intermolecular homologous recombination between transfected sequences in mammalian cells is primarily nonconservative

Intermolecular recombination in mammalian cells was studied by coinfecting African green monkey cells in culture with two shuttle vector plasmids, each carrying an incomplete but overlapping portion of the gene for neomycin resistance. The region of homology between the two plasmids was about 0.6 kilobases. Recombination between the homology regions could reconstruct the neomycin resistance gene, which was monitored by analysis of progeny plasmids in bacteria. The individual plasmids carried additional markers which, in combination with restriction analysis, allowed the determination of the frequency of formation of the heterodimeric plasmid which would be formed in a conservative recombination reaction between the homologous sequences. Reconstruction of the neomycin resistance gene was readily observed, but only 1 to 2% of the neomycin resistance plasmids had the structure of the conservative heterodimer. Treatment of the plasmids which enhanced the frequency of the neomycin resistance gene reconstruction reaction did not significantly increase the relative frequency of conservative product plasmids. The results support nonconservative models for recombination of these sequences.

UV Irradiation induces an activity which stimulates Simian virus 40 rescue upon cell fusion.

UV irradiation of African green monkey cells greatly stimulated efficiency of simian virus 40 induction from simian virus 40-transformed Syrian hamster cells after cell fusion. The maximum inducing activity was observed at 15 to 20 h after irradiation but remained only transiently. The addition of cycloheximide after UV irradiation eliminated the stimulation of the activity.

UV Irradiation induces an activity which stimulates Simian virus 40 rescue upon cell fusion

UV irradiation of African green monkey cells greatly stimulated efficiency of simian virus 40 induction from simian virus 40-transformed Syrian hamster cells after cell fusion. The maximum inducing activity was observed at 15 to 20 h after irradiation but remained only transiently. The addition of cycloheximide after UV irradiation eliminated the stimulation of the activity.