Molecular characterization of the fate of transgenes in transformed wheat (Triticum aestivum L.)

Molecular analysis of the transgenes bar and gus was carried out over successive generations in six independent transgenic lines of wheat, until the plants attained homozygosity. Data on expression and integration of the transgenes is presented. Five of the lines were found to be stably transformed, duly transferring the transgenes to the next generation. The copy number of the transgenes varied from one to five in the different lines. One line was unstable, first losing expression of and then eliminating both the transgenes in R3 plants. Although the gus gene was detected in all the lines, GUS expression had been lost in R2 plants of all but one line. Rearrangement of transgene sequences was observed, but it had no effect on gene expression. All the stable lines were found to segregate for transgene activity in a Mendelian fashion.     

Influence of sarmesin on some dopamine-related types of behaviour

Summary The present study was undertaken to investigate the effects of sarmesin, an analogue of [Sar¹] angiotensin II (ANG II) where the tyrosine hydroxyl group in position 4 is methylated, on dopamine (DA)-related paradigms: locomotor and exploratory behaviour as well as apomorphine (3 mg/kg, ip)-induced stereotypy in rats. Sarmesin (0.5 and 1 g, icv) significantly decreased ambulation and rearing movements, and blocked the inhibitory effect of ANG II (0.1 g) on both types of activity. Sarmesin induced biphasic effects on apomorphine-induced stereotypy depending on the dose increase (0.5 and 5 g, icv) and decrease (10 g). Moreover, sarmesin (5 g) blocked the inhibitory effect of ANG II (2 g, icv) on apomorphine stereotypy. Taken together, these results suggest that sarmesin might interact with AT₁ and AT₂ receptor subtypes. The results further confirm the statement for ANG II-DA interaction in brain structures involved in these types of behaviour.     

Dihydroquercetin polymerization using laccase immobilized into an ionic liquid

It was shown that the laccase (LC) included into hydrophobic ionic liquid (IL) can be reused for the biotransformation of dihydroquercetin (DHQ). The physicochemical characteristics of DHQ oligomers synthesized using LC/IL did not differ from the characteristics of the oligomers obtained with native laccase. The synthesized oligomers have a number average molecular weight of 1050 g/mol and a polydispersity index of 1.41. Oligomers possess higher antioxidant activity than the monomer.     

Determination of plasma density from data on the ion current to cylindrical and planar probes

To improve probe methods of plasma diagnostics, special probe measurements were performed and numerical models describing ion transport to a probe with allowance for collisions were developed. The current–voltage characteristics of cylindrical and planar probes were measured in an RF capacitive discharge in argon at a frequency of 81 MHz and plasma densities of 10¹⁰–10¹¹ cm^–3, typical of modern RF reactors. 1D and 2D numerical models based on the particle-in-cell method with Monte Carlo collisions for simulating ion motion and the Boltzmann equilibrium for electrons are developed to describe current collection by a probe. The models were used to find the plasma density from the ion part of the current–voltage characteristic, study the effect of ion collisions, and verify simplified approaches to determining the plasma density. A 1D hydrodynamic model of the ion current to a cylindrical probe with allowance for ion collisions is proposed. For a planar probe, a method to determine the plasma density from the averaged numerical results is developed. A comparative analysis of different approaches to calculating the plasma density from the ion current to a probe is performed.     

Regulation of exotoxin A synthesis in Pseudomonas aeruginosa: characterization of toxA-lacZ fusions in wild-type and mutant strains

A mobilizable plasmid which carries the promoter for the exotoxin A (ETA) structural gene fused to lacZ was integrated into the chromosome of wild-type and mutant strains of Pseudomonas aeruginosa at the toxA locus by homologous recombination. beta-galactosidase synthesis in the strains (cointegrates) carrying the toxA-lacZ fusions was regulated like ETA synthesis is in P. aeruginosa. Two multicopy plasmids carrying a positive regulatory gene designated toxR were constructed which are identical except with respect to the orientation of toxR to the lacZ promoter on the plasmid. These plasmids were then introduced into P. aeruginosa cointegrate strains. When toxR was using its own promoter, synthesis of beta-galactosidase in the cointegrate strains was increased but the pattern of iron regulation was not altered. In contrast, when the lacZ promoter was directing synthesis of the toxR product in the cointegrate strains, iron regulation of beta-galactosidase and ETA synthesis were abolished.     

Characterization and regeneration of wheat (Triticum aestivum L.) embryogenic cell suspension cultures

Summary Stable cell suspension cultures were established from two types of calli (one compact, nodular and embryogenic, the other friable and embryogenic) derived from cultured immature embryos of wheat (cv FLA302). Only aged calli, which had been subcultured for at least 5–8 months, formed suspensions comprised mainly of groups of small, round, densely cytoplasmic, starch-containing cells. Only the embryogenic suspension derived from the aged, compact and nodular callus formed distinct somatic embryos when plated on regeneration media containing IAA and zeatin. Upon subsequent transfer to fresh regeneration medium more than 200 green rooted plants were obtained.Abbreviations 6-BA 6-benzylaminopurine - CH casein hydrolysate - 2,4-D 2,4-dichlorophenoxyacetic acid - GA₃ gibberellic acid - IAA indole-3-acetic acid - IBA indole-3-butyric acid - MS Murashige and Skoog (1962) basal medium - NAA naphthaleneacetic acid - PCV packed cell volume     

Formation of callus and somatic embryos from protoplasts of a commercial hybrid of maize (Zea mays L.)

Summary Protoplasts isolated from a totipotent embryogenic cell suspension culture of Zea mays L. (cultivar Dekalb XL82) underwent sustained cell divisions when cultured in liquid as well as agarose media. Optimal colony formation (5%) occurred in a liquid medium containing 0.5 mg/l 2,4-dichlorophenoxyacetic acid (2,4-D). A soft and unorganized callus was formed when the protocolonies were transferred to agar solidified suspension maintenance medium. Compact, organized and yellow to pale green folded structures and somatic embryos were formed upon subsequent transfer of this callus to a low 2,4-D medium. Clusters of somatic embryos germinated precociously but no plants were recovered.     

Rearrangements in the mitochondrial genome of somatic hybrid cell lines of Pennisetum americanum (L.) K. Schum. + Panicum maximum Jacq.

Summary Mitochondrial DNA from three somatic hybrid cell lines of Pennisetum americanum + Panicum maximum was compared with mitochondrial DNA of the parents. Gel electrophoresis of BamHI-restricted mitochondrial DNA indicated that extensive rearrangements had occurred in each of the three hybrid lines. The hybrid restriction patterns showed a combination of some bands from each parent plus novel fragments not present in either parent. Additional evidence for rearrangements was obtained by hybridization of eight DNA probes, carrying sequences of known coding regions, to Southern blots. Each of the somatic hybrids exhibited a partial combination of the parental mitochondrial genomes. These data suggest recombination or amplification of the mitochondrial genomes in the somatic hybrids.