Solasodine accumulation in regenerated plants of Solanum torvum Sw / Acúmulo de solasodina em plantas micropropagadas de Solanum torvum Sw

A nodal segment culture was developed in order to assess Solanum torvum Sw. regeneration and solasodine levels. The influence of auxins (indoleacetic acid, 1-Naphthaleneacetic acid) and benzyl adenine on S. torvum growth in micropropagation was investigated. A nodal segment culture was initiated with seeds germinated in MS basal medium added of GA3 and grown in different concentrations of IAA, IAA + BAP and NAA + BAP. Sixty-day-old plants from the in vitro culture were collected, frozen and lyophilized; then, the methyl orange method was used to quantify solasodine for the spectrophotometric assay. The best results regarding plant regeneration and solasodine accumulation were obtained by using the MS basal medium without addition of plant growth regulators; however, there was great production of calluses presenting friable bases. Based on these results, cell cultures can be initiated from such calluses with application of other auxins and cytokinins to enhance solasodine production, besides different elicitors, light intensities and sucrose concentrations.

A regeneração de Solanum torvum e a avaliação do conteúdo de solasodina foram os objetivos de cultura de segmentos nodais. A influência de auxinas (ácido 3-indolacético, ácido naftalenoacético) e de 6-benzilaminopurina no crescimento de S. torvum na micropropagação foi investigado. Cultura de segmentos nodais foi iniciada por sementes germinadas em meio básico MS acrescido de GA3 e cultivadas em diferentes concentrações de AIA, AIA + BAP e ANA + BAP. Plantas da cultura in vitro com 60 dias foram coletadas, congeladas e liofilizadas e o método de alaranjado de metila foi utilizado para quantificação de solasodina para o ensaio espectrofotométrico. Os melhores resultados para regeneração vegetal e acúmulo de solasodina foram alcançados no meio MS sem adição de reguladores de crescimento havendo, porém grande produção de calos de base friáveis. Esses resultados mostram que a partir desses calos, cultura de células pode ser iniciada com aplicação de outras auxinas e citocininas para o aumento da produção de solasodina além de diferentes eliciadores, intensidades luminosas e concentrações de sacarose.

Pharmacological and phytochemical studies of callus culture extracts from Alternanthera brasiliana.

This work describes the establishment of callus cultures of Alternanthera brasiliana, a Brazilian medicinal plant used to treat several ailments. In addition the two extracts, exhibiting best yields, were chemically analysed and evaluated as antinociceptive agents in two classical models of pain in mice: the writhing test and the formalin test. The results show that the highest biomass accumulation was observed in callus grown in media with higher concentrations of growth regulator of 2,4-D. Both extracts studied exhibited antinociceptive effects in mice, being more effective than the plant extracts. The pharmacological action seems to be related to the presence of steroids and/or terpenes.

The presence of concanavalin A and canatoxin in Canavalia ensiformis DC tissue culture.

Isolated embryos, cotyledons and embryos plusa fragment of cotyledon from seeds of Canavalia ensiformis (jack bean) were cultured in vitro. Concanavalin A and canatoxin cross-reactive material were detected by double immunodiffusion tests. Canatoxin was detectable until 30 days in cultures of embryos, embryos plus cotyledons and hypocotyls. Concanavalin A was also present in all cultures being detected until 90 days in cultures treated with 6-benzylaminopurine. No concanavalin A was detected in root cultures. Concanavalin A was present in cell suspensions until 45 days of culture; the culture medium contained neither concanavalin A nor canatoxin. Tissue cultures thus can produce Con A and CNTX and will be an important research tool for studying the biosynthesis of such substances.

Developmental changes induced by gamma irradiation in Ipomoea batatas L. Lam (sweet potato).

Storage roots of Ipomoea batatas L. Lam were exposed to gamma irradiation at 90, 180, and 240 Gy. The two highest doses caused a delay in the initiation of rooting and especially of shooting; they also caused formation of rosette-like, stemless shoots without apical meristems. The storage roots irradiated with 90 Gy did form stems, but 50% of them had no apical meristem. The irradiated storage roots produced absorbent roots which developed shoots after 70 days of growth. Nonirradiated storage roots did not differentiate shoots from the absorbent roots. When grown in vitro, phytomers, stem segments with leaves and an axillary meristem, separated from the shoots of irradiated storage roots and exhibited growth aberrations, very intense rooting, and a delay in shooting. Phytomers from nonirradiated normal plants were irradiated with 10, 20, 30, 40, and 90 Gy and grown in a hormone-free medium. The 40- and 90-Gy doses delayed shooting as well as rooting. Only phytomers exposed to 40 and 90 Gy differentiated shoots from the absorbent roots. A stimulation of growth revealed in the accumulation of dry mass was found in the shoots of phytomers irradiated with 10 to 30 Gy. The long after-effects of irradiation as well as possible causes of growth stimulation are discussed.

Scanning electron microscopy of the electric organs of Electrophorus electricus L. II. Organs of Sachs and Hunter.

The surfaces of the organs of Sachs and Hunter of Electrophorus electricus L. were examined by scanning electron microscopy. Special attention was directed to morphological details of the electrocyte to provide a better understanding of its anterior and posterior faces. Some aspects of the microanatomy of these organs, which differ markedly from those of the main electric organ, provide new information on the structure as revealed previously by light and transmission electron microscopy. The relief, mainly expressed by papillae, is related to the actual membrane area, which is important for calculations of specific resistance and conductance. Information is also presented on the general organization of the tissue, in particular the distribution of the connective elements and external configuration of synaptic terminals. Shrinkage in preparation of tissue was evaluated and correction made whenever necessary. Correction factors for actual membrane area were calculated for anterior and posterior faces of electrocytes from both organs.

Scanning electron microscopy of the electric organs of Electrophorus electricus L. I. Main organ.

Extensive survey was made with a scanning electron microscope (SEM) of the surfaces of the main electric organ of Electrophorus electricus L. This study of the microanatomy of the electrocyte contributes to a better understanding of the relief of both anterior and posterior faces, showing peculiarities that could not be seen previously in sections either for light or for electron microscopy. The relief is evidently related to the actual membrane area, important for calculations of electrophysiological parameters. Also information on the general organization, specially the distribution of connective tissue and external configuration of synapses, is presented.

Electrocyte physiology: I. Temperature dependence of membrane excitability.

Some membrane characteristics of the isolated electrocyte of the Sachs organ are presented as function of temperature. Excitability curves are shown for electrocytes kept in standard saline at different temperatures. It is shown that rheobase varies directly with temperature. Apparently membrane resistance varies from 4.9 omega . cm2at 20 degrees C to 11.4 omega . cm2 at 5 degrees C and membrane capacity from 51,0 muF/cm2 to 48.4 muF/cm2 respectively. The relatively low resistance and high capacitance of this membrane may be due to an incorrect assessment of surface area owing to infolding.