Stimulation of gibberellin activity in winter wheat by metribuzin

Sublethal doses of metribuzin applied to wheat plants at the stage of ear emergence increased endogenous gibberellin levels in the ears. The activation of hormonal systems in connection with “chemical stress” is briefly discussed.     

Antiepileptic effects of amphetamine may require GABA (benzodiazepine) activity

Secondary components of visual evoked potentials (slow negative wave-SNW, and photically-evoked sensory afterdischarge-SAD) are known to be precursors of experimentally activated wave-spike discharges, similar to wave-spikes of petit mal epilepsy. Both SNW and SAD may be potently suppressed wither by amphetamine or GABAergic compounds such as diazepam and sodium valproate. A hypothesis was tested in the present study, that amphetamine-induced suppression of wave-spike discharges may require GABA-benzodiazepine activity for its expression.Electrocortical activity was recorded and averaged in unrestrained albino rats with chronically implanted epicortical electrodes. SNW and SAD obtained in habituated rats in the predrug state were potently suppressed by amphetamine (1 mg/kg, i.p.). Fifteen minutes after amphetamine injection, a challenging drug (metrazol, picrotoxin, convulsant benzodiazepine, Ro 5-3663, or imidazodiazepine, Ro 15-1788) was administered intraperitoneally. Subconvulsive doses of metrazol (10 mg/kg) reversed amphetamine suppression; imidazodiazepine (20 mg/kg) and picrotoxin (1.5 mg/kg) reliably opposed the SNW suppression; convulsant benzodiazepine, Ro 5-3663 (2 mg/kg), showed modest and nonsignificant effect in the same direction. It is proposed that the antiepileptic potency of amphetamine may be associated with its ability, apparently via modulatory effect of norepinephrine, to facilitate the activation of benzodiazepine-GABA receptors.     

Temperature-related divergence in experimental populations of Drosophila melanogaster. II. Correlation between fitness and body dimensions

From a laboratory stock of Drosophila melanogaster (Oregon), reared for more than 20 years at 18° C, a new population was derived and maintained at 28° C for 8 years. The chromosomal and cytoplasmic contribution to genetic divergence between the two populations was estimated. Six body traits and reproductive fitness were taken into account. The third chromosome is responsible for the adaptive difference for temperature between the two lines. Temperature-selected genes which control body size are located on the second and third chromosomes, although the contribution of each chromosome depends on the environment in which the flies develop. The correlation between the chromosomal and cytoplasmic contributions to different traits and fitness, changes with temperature. At 28° C the correlation between fitness and each body trait is proportional to the response to selection exhibited by each of them, but this is not true at 18° C. Body size has, therefore, an adaptive significance in relation to temperature, which is expressed only in the environment where selection occurs. Cytoplasmic genes affect almost all characters to an extent similar to that of chromosomal genes. Inter-chromosomal and nucleo-cytoplasmic interactions are present and also change with temperature. In general, genes selected in a given environment produce greater phenotypic changes in that environment than in another. The population that experienced both temperatures is fitter in both environments, suggesting that the capacity to adapt to warm temperatures depends on genes other than those which are involved in the adaptation to cold.     

Size-related differences in parietal extrapleural and pleural liquid pressure distribution

The hydraulic pressure in the extrapleural parietal interstitium (Pepl) and in the pleural space over the costal side (Pliq) was measured in anesthetized spontaneously breathing supine adult mammals of increasing size (rats, dogs, and sheep) using saline-filled catheters and cannulas, respectively. From the Pliq and Pepl vs. lung height regressions it appears that in all species Pliq was significantly more subatmospheric than Pepl simultaneously measured at the same lung height. The vertical pleural liquid pressure gradient increased with size, amounting to -1, -0.69, and -0.44 cmH2O/cm in rats, dogs, and sheep, respectively. The vertical extrapleural liquid pressure gradient also increased with size, being -0.6, -0.52, and -0.33 cmH2O/cm in rats, dogs, and sheep, respectively. With increasing body size, the transpleural hydraulic pressure gradient (Ptp = Pepl - Pliq) at the level of the right atrium increased from 1.45 to 5.6 cmH2O going from rats to sheep. In all species Ptp increased, with lung height being greatest in the less dependent part of the pleural space.     

Distribution of diaphragmatic lymphatic stomata

In seven anesthetized rabbits we measured the size, shape, and density of lymphatic stomata on the peritoneal and pleural sides of the diaphragm. The diaphragm was fixed in situ and processed for scanning electron microscopy. Results are from 2,902 peritoneal and 3,086 pleural fields (each 1,620 microns 2) randomly chosen from the various specimens. Stomata were seen in 9% of the fields examined, and in 30% of the cases they appeared grouped in clusters with 2-14 stomata/field. Stoma density was 250 +/- 242 and 72 +/- 57 (SD) stomata/mm2 on peritoneal and pleural sides, respectively, and it was similar over the muscular and tendinous portion of the two surfaces. The maximum diameter ranged from less than 1 to approximately 30 microns, with an average value of 1.2 +/- 3.1 micron. The ratio of the maximum to the minimum diameter and the surface area averaged 2 +/- 1.4 and 0.7 +/- 2.4 micron 2, respectively. The maximum and minimum diameter and surface area values followed a lognormal frequency distribution, suggesting that stomata geometry is affected by diaphragmatic tension.     

Effect of exogenous amino acids on the intracellular content of proline and other amino acids in Daucus carota cells

The effect of tryptophan on the biosynthesis of proline has been investigated. Cells of Daucus carota grown in B5 medium supplemented with 5×10^–4M tryptophan acquired the ability to grow in the presence of inhibitory concentrations of azetidine-2-carboxylic acid, an analog of proline. When trp was added to carrot cell cultures at sub-growth inhibiting concentrations, overproduction of intracellular free proline was observed. An increase was also observed for lys, his, ala, leu and phe. Likewise, the addition of asparagine, glutamic acid and phenylalanine to the medium stimulated the intracellular increase of free proline and other amino acids.Abbreviations A2CA azetidine-2-carboxylic acid - 2,4-D 2,4-dichlorophenoxyacetic acid - 5MT 5-methyltryptophan - P5C pyrroline-5-carboxylic acid - f.wt. fresh weight - d.wt. dry weight     

The incidence of Listeria spp. in soft cheeses, butter and raw milk in the province of Bologna

Samples of soft cheese, butter and raw milk were examined for Listeria species. Listeria monocytogenes (serotype 1, haemolytic and virulent for mice) and L. innocua (the only other Listeria sp. isolated) were each found in 2/21 (1.6%) of soft cheese samples. Five per cent of butter samples were contaminated with L. innocua . No Listeria spp. were detected in 40 raw milk samples. The results were compared with similar studies in Italy and abroad. and accepted 14 June 1989     

Cloning and characterization of a 70 kd heat shock cognate (hsc70) gene from the zebrafish (Danio rerio)

The heat shock 70 family of proteins is one of the most highly conserved among all species. The genes encoding these proteins have been cloned and sequenced from bacterial species to humans with a high degree of homology preserved throughout evolution. Here we describe the cloning and characterization of a cDNA encoding a 70 kd heat shock cognate (hsc70) gene from the zebrafish (Danio rerio). A high degree of conservation is observed among hsc70 genes of other species as shown by phylogenetic analysis. The characterization of a hsc70 gene in the zebrafish provides a marker for studying the role of a constitutively expressed member of the hsp70 family in an important developmental and evolutionary model system.     

Production of taxanes by Taxus baccata plant cells

In callus cultures of Taxus baccata grown on agar media according to Murashige and Skoog supplemented with different growth hormones 8 taxol analogues were identified.