The expression of the genes encoding the four proteins (P, H, T, and 1) of glycine decarboxylase, a multienzymatic complex involved in the mitochondrial step of the photorespiration pathway, was examined during pea (fisum sativum) leaf development in comparison with ribulose-l,5-bisphosphate carboxylase/oxygenase. Mitochondria from the primary leaf were isolated at severa1 welldefined stages of development. Their capacity to oxidize glycine was negligible during the earlier stages but increased dramatically once the leaflet opened. This was correlated with the accumulation of the glycine decarboxylase complex (CDC) proteins, which was shown to occur in preexisting mitochondria, producing an increase in their density. The transcription of the CDC genes was coordinated and occurred early, with a peak at 7 d, a stage at which mitochondria are unable to oxidize glycine. This implies the existente of posttranscriptional control of gene expression. The comparison of the expression patterns of the genes encoding specific proteins of CDC with that of rbcS genes suggests a common regulation scheme that is related to light induction. However, ribulose-1,5-bisphosphate carboxylase/oxygenase is present in the chloroplast well before CDC fills the mitochondria, suggesting that the setup of photorespiration occurs in cells already engaged in active photosynthesis.

RP 59500, a new antibacterial agent, is a combination of two compounds, RP 54476 and RP 57669. The uptake of radiolabelled RP 59500, i.e. a mixture containing [14C]-RP 54476 plus RP 57669 or [14C]-RP 57669 plus RP 54476, by J 774 murine macrophages was evaluated by a velocity gradient centrifugation technique. After 120 min, the ratios of cellular to extracellular concentration for RP 54476 and RP 57669 were 34 and 50, respectively. The highest intracellular accumulation of RP 59500 was observed at pH 7-7.5. RP 59500 was found to accumulate less at 4 degrees C than at 37 degrees C. The uptake of RP 59500 by dead macrophages was markedly higher than that by live macrophages. As the extracellular concentration of RP 59500 was increased, the intracellular concentration of each component rose, but not proportionally. The metabolic inhibitors sodium cyanide and potassium fluoride both decreased modestly the entry of RP 57669, but not that of RP 54476, into macrophages. After removal of the extracellular antibiotic, RP 54476 and RP 57669 were released rapidly by the cells until equilibrium was established (45% of the original intracellular RP 59500 remained in the cells after 120 min). The intracellular activity of RP 59500 was assessed by incubating macrophages containing ingested Staphylococcus aureus 209P with the drug (10 x MIC: 2.5 mg/L) at 37 degrees C and determining the number of viable cell-associated bacteria. Approximately 70% of the intracellular bacteria were killed within 120 min of incubation. Thus, RP 59500 attains a high intracellular concentration and is active against intracellular S. aureus.

The in-vitro and in-vivo uptake of spiramycin by human and animal alveolar macrophages was studied. In-vitro penetration was studied in guinea pig and human alveolar macrophages incubated in medium 199 at 37 degrees C containing spiramycin at various concentrations. Results were expressed as the cellular/extracellular concentration ratio (C/E). The in-vivo study was performed in patients receiving 500 or 1000 mg spiramycin every 8 h as a 1-h infusion on day 1. A single infusion was given on day 2, 2 h before serum and bronchoalveolar lavage (BAL) sampling. Spiramycin was assayed by HPLC, and by a microbiological assay. In guinea pig alveolar macrophages, the C/E ratio of spiramycin after 60 min at 37 degrees C was 20.3 +/- 6.5 when the concentration was 10 mg/l. In human alveolar macrophages, the C/E ratio was 21.3 +/- 8.7 at 5 mg/l spiramycin and 23.8 +/- 8.7 at 50 mg/l. The accumulated spiramycin was slowly released when the cells (guinea pig alveolar macrophages) were washed and re-incubated in antibiotic free medium. Spiramycin was able to penetrate the alveolar space. In BAL supernatant, spiramycin levels were about 24-fold the serum level (n = 6 patients), when the BAL/serum glucose ratios were used as the dilution estimate. Alveolar macrophage levels ranged from 17 to 210 mg/l (n = 6 patients receiving 500 mg spiramycin infusion). These results are consistent with the in-vitro data.

Adaptation to low water and soil P availability has been related to root properties. Two experiments were conducted in a greenhouse. Under hydroponics conditions, plants of the Souna 3 cultivar were grown for 30 d with three levels of P (P0 = 0.0 mol L−1, P1 = 0.073 10−3mol L−1, and P2 = 1.65 10−3 mol L−1). In the pot experiment, two cultivars (Souna 3 and IBMV8402) were planted in pots filled with 19 kg of P‐deficient and sandy soil and subjected to two watering regimes: well watered and water stressed at the vegetative phase from 23 d after sowing (DAS) to 30 DAS. Phosphorus treatment consisted of two levels: application of phosphate fertilizer (P2O5) at the rate of 649 mg per pot (34 mg P2O5 kg−1 soil), referred to as F1, and no phosphate application, referred to as F0. The results showed that under P deficiency, pearl millet [Pennisetum glaucum (L.) R. Br.] presented an alteration of root parameters, particularly root volume, by the formation of root hair. Under non‐water‐limited conditions as well as in high or low P, IBMV8402 showed a better root and shoot growth. However, under drought conditions, the leaf water potential (Ψf) of IBMV8402 (Ψf = −5 MPa) decreased more than that of Souna 3 (Ψf = −3 MPa). In spite of this, P supply improved the root and shoot growth of IBMV8402. Finally, except for the condition of water stress and without P supply, P utilization efficiency exhibited by IBMV8402 was 20 to 50% higher than that of Souna 3 on the basis of shoot biomass production.

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We investigated the effect of sparfloxacin, a new broad-spectrum fluoroquinolone, on the morphology, adhesiveness and phagocytosis of a clinical isolate of Staphylococcus aureus sensitive to this compound (MIC = 0.06 mg/L). The strain was tested for its adherence to human buccal epithelial cells, measured by interference contrast microscopy, and for phagocytosis by guinea-pig peritoneal macrophages, measured by fluorescence microscopy. Accumulation of sparfloxacin by macrophages was studied by means of a velocity-gradient centrifugation technique. The S. aureus strain, grown in the presence of sub-inhibitory concentrations of sparfloxacin, exhibited an increased cell diameter and a markedly reduced capacity to adhere to buccal epithelial cells. The phagocytic capacity and activity of macrophages were greater with the treated strain than with an untreated control. A reduction in numbers of intracellular cocci was also observed 2 h after postphagocytic treatment of macrophages with sparfloxacin at 10 x MIC. This intracellular bactericidal activity may result from accumulation of sparfloxacin in macrophages, evidenced by a high ratio of cellular to extracellular concentration. It was concluded that sparfloxacin reduces adherence to epithelial cells, increases phagocytosis and facilitates the intracellular killing of S. aureus.

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