Cryopreservation of Arachis pintoi (leguminosae) somatic embryos.

In this study, we successfully cryopreserved cotyledonary somatic embryos of diploid and triploid Arachis pintoi cytotypes using the encapsulation-dehydration technique. The highest survival rates were obtained when somatic embryos were encapsulated in calcium alginate beads and precultured in agitated (80 rpm) liquid establishment medium (EM) with daily increasing sucrose concentration (0.50, 0.75, and 1.0 M). The encapsulated somatic embryos were then dehydrated with silica gel for 5 h to 20% moisture content (fresh weight basis) and cooled either rapidly (direct immersion in liquid nitrogen, LN) or slowly (1 degree C per min from 25 degree C to -30 degree C followed by immersion in LN). Beads were kept in LN for a minimum of 1 h and then were rapidly rewarmed in a 30 degree C water-bath for 2 min. Finally, encapsulated somatic embryos were post-cultured in agitated (80 rpm) liquid EM with daily decreasing sucrose concentration (0.75 and 0.5 M) and transferred to solidified EM. Using this protocol, we obtained 26% and 30% plant regeneration from cryopreserved somatic embryos of diploid and triploid cytotypes. No morphological abnormalities were observed in any of the plants regenerated from cryopreserved embryos and their genetic stability was confirmed with 10 isozyme systems and nine RAPD profiles.

Genetic stability in rice micropropagation.

An efficient clonal propagation procedure for six rice varieties cultivated in Argentina was developed by using shoot tip cultures, and the genetic stability of the micropropagated plants was verified by isozyme analysis. One week old seedlings obtained on MS medium were sectioned and subcultured on MS medium (0.75% agar) supplemented with different combination and concentrations of cytokinins (BAP and KIN) and auxins (2,4-D and NAA). After four weeks of culture, multiple shoots were obtained. The best response was observed on MS supplemented with BAP 5 mg l(-1). Shoot clumps were multiplied in MS liquid medium containing BAP 5 mg l(-1). Profuse rooting was obtained after transfer to MS medium lacking growth regulators and with sucrose 8% (w/v). Complete plants were successfully transferred to soil and grown to maturity. ADH and EST patterns of micropropagated rice plants showed polymorphisms compared with plants of the original varieties. However, the zymograms of the seed derived progeny of the micropropagated plants were similar to that of the original varieties. These results indicate the maintenance of the genetic stability in the sexual progeny of micropropagated plants.

Genetic stability in rice micropropagation

An efficient clonal propagation procedure for six rice varieties cultivated in Argentina was developed by using shoot tip cultures, and the genetic stability of the micropropagated plants was verified by isozyme analysis. One week old seedlings obtained on MS medium were sectioned and subcultured on MS medium (0.75% agar) supplemented with different combination and concentrations of cytokinins (BAP and KIN) and auxins (2,4-D and NAA). After four weeks of culture, multiple shoots were obtained. The best response was observed on MS supplemented with BAP 5 mg l(-1). Shoot clumps were multiplied in MS liquid medium containing BAP 5 mg l(-1). Profuse rooting was obtained after transfer to MS medium lacking growth regulators and with sucrose 8% (w/v). Complete plants were successfully transferred to soil and grown to maturity. ADH and EST patterns of micropropagated rice plants showed polymorphisms compared with plants of the original varieties. However, the zymograms of the seed derived progeny of the micropropagated plants were similar to that of the original varieties. These results indicate the maintenance of the genetic stability in the sexual progeny of micropropagated plants. (AU)

Genetic stability in rice micropropagation

An efficient clonal propagation procedure for six rice varieties cultivated in Argentina was developed by using shoot tip cultures, and the genetic stability of the micropropagated plants was verified by isozyme analysis. One week old seedlings obtained on MS medium were sectioned and subcultured on MS medium (0.75% agar) supplemented with different combination and concentrations of cytokinins (BAP and KIN) and auxins (2,4-D and NAA). After four weeks of culture, multiple shoots were obtained. The best response was observed on MS supplemented with BAP 5 mg l(-1). Shoot clumps were multiplied in MS liquid medium containing BAP 5 mg l(-1). Profuse rooting was obtained after transfer to MS medium lacking growth regulators and with sucrose 8% (w/v). Complete plants were successfully transferred to soil and grown to maturity. ADH and EST patterns of micropropagated rice plants showed polymorphisms compared with plants of the original varieties. However, the zymograms of the seed derived progeny of the micropropagated plants were similar to that of the original varieties. These results indicate the maintenance of the genetic stability in the sexual progeny of micropropagated plants.

Genetic stability in rice micropropagation.

An efficient clonal propagation procedure for six rice varieties cultivated in Argentina was developed by using shoot tip cultures, and the genetic stability of the micropropagated plants was verified by isozyme analysis. One week old seedlings obtained on MS medium were sectioned and subcultured on MS medium (0.75

agar) supplemented with different combination and concentrations of cytokinins (BAP and KIN) and auxins (2,4-D and NAA). After four weeks of culture, multiple shoots were obtained. The best response was observed on MS supplemented with BAP 5 mg l(-1). Shoot clumps were multiplied in MS liquid medium containing BAP 5 mg l(-1). Profuse rooting was obtained after transfer to MS medium lacking growth regulators and with sucrose 8

(w/v). Complete plants were successfully transferred to soil and grown to maturity. ADH and EST patterns of micropropagated rice plants showed polymorphisms compared with plants of the original varieties. However, the zymograms of the seed derived progeny of the micropropagated plants were similar to that of the original varieties. These results indicate the maintenance of the genetic stability in the sexual progeny of micropropagated plants.

Effect of the media composition on the growth parameters and biological properties ofBacillus thuringiensis var.israelensis delta-endotoxin.

The effects of media composition on growth parameters, total protein production (including delta-endotoxin) and its relation to the biological properties ofBacillus thuringiensis var.israelensis was investigated. The replacement of glucose by glycerol as the carbon source yielded higher concentrations of delta-endotoxin. This increase in toxicity was associated with increased amounts of the 130 kDa polypeptide fraction. The biocide activity was not related to haemolytic activity. specific growth rate nor spore count.

[Influence of various ions in sporulation and the formation of delta-endotoxin in Bacillus thuringiensis cultures]. / Influencia de algunos iones en la esporulación y formación de delta-endotoxina en cultivos de Bacillus thuringiensis.

This paper deals with studies related to the influence of several ions on growth, spore formation and endotoxin formation by a Bacillus thuringiensis HD-1 strain commonly used for bioinsecticide production. Two basal media (4 and 5, Table 1) containing glucose, (NH4)2 SO4, phosphates and yeast extract or bacto peptone as organic nitrogen sources were supplemented with several ions in different concentrations, as shown in table 1. The experiments were conducted in 1000 ml Erlenmeyer flasks, containing 100 ml of medium, located in a rotary shaker at 30 degrees C. Several estimations were carried out, mainly biomass by optical density and colony forming units (CFU), glucose, Mg+2 and Mn+2 consumption and delta-endotoxin by a rocket immunoelectrophoretic method. The results obtained (Table 2) clearly show the importance of the addition of Ca+2, Mg+2 and Mn+2 to the basal media, because the highest values of CFU/l and delta-endotoxin (expressed as protein in g/l) were achieved in those media supplemented with the ions mentioned. It was also proved that the supplementation with Ca+2 was also essential for maintaining the thermal stability of the spores (Table 3). It can be concluded that an adequate formulation of media mainly related with the content of Mn+2, Mg+2 and Ca+2 is essential for obtaining high yields of spore crystal production of a Bacillus thuringiensis HD-1 strain.

Influencia de algunos iones en la esporulación y formación de delta-endotoxina en cultivos de Bacillus thuringiensis. / [Influence of various ions in sporulation and the formation of delta-endotoxin in Bacillus thuringiensis cultures]

This paper deals with studies related to the influence of several ions on growth, spore formation and endotoxin formation by a Bacillus thuringiensis HD-1 strain commonly used for bioinsecticide production. Two basal media (4 and 5, Table 1) containing glucose, (NH4)2 SO4, phosphates and yeast extract or bacto peptone as organic nitrogen sources were supplemented with several ions in different concentrations, as shown in table 1. The experiments were conducted in 1000 ml Erlenmeyer flasks, containing 100 ml of medium, located in a rotary shaker at 30 degrees C. Several estimations were carried out, mainly biomass by optical density and colony forming units (CFU), glucose, Mg+2 and Mn+2 consumption and delta-endotoxin by a rocket immunoelectrophoretic method. The results obtained (Table 2) clearly show the importance of the addition of Ca+2, Mg+2 and Mn+2 to the basal media, because the highest values of CFU/l and delta-endotoxin (expressed as protein in g/l) were achieved in those media supplemented with the ions mentioned. It was also proved that the supplementation with Ca+2 was also essential for maintaining the thermal stability of the spores (Table 3). It can be concluded that an adequate formulation of media mainly related with the content of Mn+2, Mg+2 and Ca+2 is essential for obtaining high yields of spore crystal production of a Bacillus thuringiensis HD-1 strain.

[Production of glucose isomerase by Streptomyces phaeochromogenes]. / Producción de glucosa-isomerasa por Streptomyces phaechromogenes.

The production of glucose isomerase was studied in the Streptomyces phaeochromogenes NRRL B-3559 strain. The influence of the medium composition and the aeration conditions was determined Selection of colonies was necessary to obtain the best results. A grey colony proved to be the most productive one. It was necessary to use the frozen inocula in order to obtain steady reproduction values. It was possible to achieve the maximum enzymatic level (1600 UE/1 min) using a CoCl2. 6H2O concentration of 0.18 g/l. The aeration studies conducted in a mechanically stirred fermentor showed results comparable to those obtained in shaker flasks, operating at 550 rpm and using an air flow of 1 1/1 min. The culture proved to properly aerated since both the cellular oxygen uptake and oxygen demand were similar (Table 1).

Producción de glucosa-isomerasa por Streptomyces phaechromogenes. / [Production of glucose isomerase by Streptomyces phaeochromogenes]

The production of glucose isomerase was studied in the Streptomyces phaeochromogenes NRRL B-3559 strain. The influence of the medium composition and the aeration conditions was determined Selection of colonies was necessary to obtain the best results. A grey colony proved to be the most productive one. It was necessary to use the frozen inocula in order to obtain steady reproduction values. It was possible to achieve the maximum enzymatic level (1600 UE/1 min) using a CoCl2. 6H2O concentration of 0.18 g/l. The aeration studies conducted in a mechanically stirred fermentor showed results comparable to those obtained in shaker flasks, operating at 550 rpm and using an air flow of 1 1/1 min. The culture proved to properly aerated since both the cellular oxygen uptake and oxygen demand were similar (Table 1).