Somaclonal variation: a morphogenetic and biochemical analysis of Mandevilla velutina cultured cells

Cell cultures of Mandevilla velutina have proved to be an interesting production system for biomass and secondary metabolites able to inhibit the hypotensive activity of bradykinin, a nonapeptide generated in plasma during tissue trauma. The crude ethyl acetate extract of cultured cells contains about 31- to 79-fold more potent anti-bradykinin compounds (e.g., velutinol A) than that obtained with equivalent extracts of tubers. Somaclonal variation may be an explanation for the wide range of inhibitor activity found in the cell cultures. The heterogeneity concerning morphology, differentiation, carbon dissimilation, and velutinol A production in M. velutina cell cultures is reported. Cell cultures showed an asynchronous growth and cells in distinct developmental stages. Meristematic cells were found as the major type, with several morphological variations. Cell aggregates consisting only of meristematic cells, differentiated cells containing specialized cell structures such as functional chloroplasts (cytodifferentiation) and cells with embryogenetic characteristics were observed. The time course for sucrose metabolism indicated cell populations with significant differences in growth and metabolic rates, with the highest biomass-producing cell line showing a cell cycle 60 percent shorter and a metabolic rate 33.6 percent higher than the control (F2 cell population). MALDI-TOF mass spectrometric analysis of velutinol A in selected cell lines demonstrated the existence of velutinol A producing and nonproducing somaclones. These results point to a high genetic heterogeneity in general and also in terms of secondary metabolite content

In vitro activity of meglumine antimoniate, a pentavalent antimonial drug, on Leishmania promastigotes

The activity of a pentavalent antimonial drug glucantime on the growth of promastigote forms of Leishmania strains involved in South American cutaneous and mucocutaneous leishmaniasis was investigated. A marked difference in susceptibility to glucantime among four different strains and cloned lines obtained from a single strain was observed. For the sensitive strains (L.braziliensis M2903 and L. guyanensis M1176), the cell growth was reduced in a dose-dependent manner for drug concentrations at a range of 0.23 to 23 mM. However, despite the relative sensitivity of the assay, no significant increase of effect was observed in the presence of higher drug concentrations. For the resistant strains (L. amazonensis M10996 and L. braziliensis LYB259) a dose-response line is obtained at a higher concentration range (20 mM to mM). The influence of the drug on surface properties, respiratory activity and incorporation of radiolabelled leucine by a sensitive strain - L-guyanensis M1176-was studied as an approach to its site of action. Despite the increased intensity of self-aglutination for cells growing in the presence of glucantime, no significant change was observed in electrophoretic mobility or Concanavian A reactivity. Since the oxygen uptake of glucose-stimulated promastigotes was only slightly reduced in the presence of 23 mM glucantime at 28-C, the reduction was not sufficient to explain the total growth inhibition observed. A significant decrease of 14C-leucine incorporation into the cold TCA-insoluble fraction of drug-treated cells was observed within the same concentration range that reduces promastigote growth