Diurnal variations in the kinetics of delayed luminescence from Scenedesmus obtusiusculus after exposure to various light and CO2 regimes

Delayed luminescence was measured from samples of a synchronously growing cell culture of the unicellular green alga, Scenedesmus obtusiusculus Chod., every second hour during the 24 h cell cycle under a 15/9 h lighi/dark regime. Both high (air + 2.5% CO₂) and low (0.03% CO₂) CO₂ conditions were used. Under high CO₂ conditions, while light excitation induces formation of a late (maximum reached after 10–60 s) transient peak in delayed luminescence in cells sampled after 10–16 h in the cell cycle. During most of the cell cycle low CO₂ conditions stimulate a late transient peak formation. Excitation with 700 nm light, but not with 680 nm light, induces a late transient peak in delayed luminescence under high CO₂ conditions. The transient peak is more or less pronounced depending on the cell stage. The variations might be due to a changing capacity for light-induced state I/stale II transitions during the cell cycle. It is assumed that the formation of a late transient peak in delayed luminescence is due to ATP hydrolyzation and is thus favoured by a high ATP/NADPH ratio. Hydrolyzation of ATP affects the transthylakoidal ΔpH, which regulates the reverse electron flow to the plastoquinone-pool and Q_A/Q_B, thus affecting the decay kinetics of the delayed luminescence.     

Niche differentiation with respect to light utilization among coexisting dwarf shrubs in a subarctic woodland

Summary Canopy structure, shoot design, and photosynthetic light recruitment were used to compare four coexisting dwarf shrub species with respect to light utilization. All four species showed different shoot designs which probably result in different light interception properties. Leaves of Vaccinium uliginosum showed the highest levels of photosynthetic light saturation but in situ the shoots of this species reached their maximum photosynthetic rate at the lowest photon flux densities. No consistent differences with respect to photosynthetic light responses were found between deciduous and evergreen species. At sites dominated by one of the deciduous species (Vaccinium uliginosum or V. myrtillus), the two evergreen species studied (V. vitis-idaea and Empetrum hermaphroditum) occurred in the understory, i.e., with their leaf distribution slightly below that of the deciduous species. Sites dominated by one of the evergreen species showed less vertical differentiation in leaf distribution between species.     

MHC nonrestricted cytotoxic T cell clones with selective specificity from patients with transitional cell carcinoma (TCC) of the urinary bladder

Summary Lymphocytes from patients with transitional cell carcinoma (TCC) of the urinary bladder are more cytotoxic to bladder tumor cells than to a variety of control cells. This disease-related cytotoxicity has previously been shown to involve several mechanisms and different types of effector cells. To analyze further the nature of the effector cells operative in this system, peripheral blood lymphocytes from eight TCC patients were stimulated in vitro with TCC extract and cultured in the presence of interleukin 2 and allogeneic feeder cells. When tested for cytotoxicity in vitro on a target cell panel including both adherent and nonadherent cell lines, the lymphocytes killed a broad spectrum of targets in a major histocompatibility complex (MHC)-unrestricted fashion. When cloned by limiting dilution, clones were obtained which displayed a more restricted pattern of target cell killing. Some of the clones were highly but not exclusively selective for TCC-derived target cells. Phenotypically, these cells resembled mature T cells of CTL-type (CD8⁺/CD4^–). They also expressed the CD3/5 T cell antigen receptor complex but target cell killing was not MHC-restricted. The results of various inhibition experiments suggested that the CD3/TCR complex was involved in the cytotoxicity exhibited by these effector cells. However, its precise role in target cell recognition and the identification of the tumor cell structures recognised by the effector cells require further studies.     

Initial Phases of Starvation and Activity of Bacteria at Surfaces

The activity of the hydrophilic Vibrio sp. strain DW1 and the hydrophobic Pseudomonas sp. strain S9, which both undergo starvation-induced responses, was examined at nutrient-enriched and nutrient-deficient interfaces. The initial period of response to a starvation regime (“dwarfing” phase) is a sequence of two processes: fragmentation and continuous size reduction of the fragmented cells. This dwarfing phase is also one of intense metabolic activity as supported by O₂ uptake measurements of the endogenous metabolism and the use of inhibitors of the proton flow, the electron transport chain, and membrane-bound ATPase. Hydrophilic bacteria become even smaller at nutrient-deficient surfaces than in the liquid phase upon starvation, and this is reflected in a higher endogenous metabolism exhibited by surface-associated cells compared with those in the liquid phase. On the other hand, hydrophobic bacteria dwarfing at surfaces did not exhibit a greater size reduction and exhibited an endogenous metabolism that was only slightly higher than that of cells in the liquid phase. Bacterial scavenging of surface-localized nutrients is related to the degree of irreversible binding of dwarf and starved bacteria, which in turn may be related to the degree of cell surface hydrophobicity.     

A RADAR STUDY OF THE AUTUMN MIGRATION OF WOOD PIGEONS COLUMBA PALUMBUS IN SOUTHERN SCANDINAVIA

The migration of Wood Pigeons in southern Scandinavia was studied from 21 September to 10 October 1971 and from 16 September to 15 November 1972 using radar stations supplemented with observations from an aircraft and a network of ground observers. By far the largest quantities of Wood Pigeons migrated after cold front passages with northwesterly to northeasterly tailwinds. Most birds departed on a few days, apparently as a consequence of strong preference for tailwind situations. With northwesterly winds a proportionately high migratory activity was recorded in the Kattegatt area. With northeasterly winds activity was higher in the Baltic area. This allowed the Wood Pigeons to make maximal use of the tailwind component, and their ground speed usually exceeded 80 km/h. The calculated mean air speed was 60 km/h. Their dependence on tailwind was particularly strong when the birds were engaging in long sea-crossings, such as across the Kattegatt. Different coastlines affected the geographical pattern of migration in different ways. Frequently Wood Pigeon flocks flew almost parallel to the coast but some distance off shore, until they finally departed. The deflective force of coastlines was greatest when the birds' ground speed was low, that is, under headwind conditions or in calm weather. Mean track directions measured over two areas in northern Skane, called Inland W and Inland E, situated about 60 km apart, differed by 11, those over the western area being directed more to the south than those over the eastern. No significant correlation with wind directions was found in these areas. Combining data from the whole land area, however, track directions were found to vary from day to day in significant correlation to the wind direction. Mean track directions over the Baltic agreed with those over Skane, but both differed significantly from those over the Kattegatt. Both over the Baltic and over the Kattegatt directions were significantly correlated with wind directions, and showed greater variation than track directions over land. Daily track differences over the Baltic resulted both from differences taking place over the land, and from real wind deflection (drift). Both over the land and over the sea heading directions were correlated with wind directions, suggesting compensatory efforts on the part of the birds. On three days extensive fog covered much of the study area. Wood Pigeons continued to migrate, but certain aberrations in their behaviour were noted. Over land migration was relatively heavier in the west with northwesterly winds and in the east with northeasterly winds. The correlation demonstrated between wind direction and the mean track direction was based upon the fact that populations with different inherent primary directions made up different proportions of the migrating cohorts under different wind conditions (pseudo-drift). The incomplete compensation for wind deflection over the sea is ascribed to the lack of visual orientation cues. The more accurate orientation possible over land suggests one reason for the birds' reluctance to flights across the open sea. When mean track directions of Wood Pigeons in different parts of southern Scandinavia were related to the migratory goals of these birds, it was found that they have to change their primary direction in the course of their journey from breeding to wintering areas.     

Mutant of Escherichia coli with Anomalous Cell Division and Ability to Decrease Episomally and Chromosomally Mediated Resistance to Ampicillin and Several Other Antibiotics

In a mutation experiment with a rough, ampicillin-resistant strain, we isolated two smooth mutants which were both sensitive to ampicillin and carried defects in the cell envelope. One of the strains (with the envA gene) is hindered in its completion of septa and forms chains of cells. The envA gene has been mapped to a position between leu and proB, at 2 to 4 min. The envA gene decreased the resistance mediated by both episomal and chromosomal genes for resistance to several antibiotics. During growth the envA mutant was characterized by abnormal ratios between viable count or cell count and optical density. The ratio between viable count and optical density was affected during shift-up and shift-down experiments. When compared to the parent strain, the envA mutant was found to be more resistant to ultraviolet irradiation on plates. Prestarvation for tryptophan had a protective effect against irradiation both on the parent strain and the envA mutant.     

Inhibition by antibiotics of the bacterial response to long-term starvation of Salmonella typhimurium and the colon microbiota of mice

The number of viable cells of two strains of Salmonella typhimurium and the number of viable cells and the cell size of the colon microbiota of mice were examined during non-growing conditions after exposure to antibiotics with known modes of action. Salmonella typhimurium starved for 1, 2, 4, 5, 12 and 20 d in a phosphate buffer saline solution and subsequently exposed for 2 and 6 h showed the following characteristics. The protein synthesis inhibitors gentamicin and tetracycline, the RNA synthesis inhibitor rifampicin and the membrane potential inhibitor polymyxin all impaired survival of starved cells. The reduction in the number of viable cells caused by the addition of gentamicin, rifampicin and polymyxin was generally more pronounced with extended exposure to energy and nutrient deprivation. Both 2- and 6-h exposure of tetracycline, however, had diminishing inhibitory effects after 20 d compared with 5 d of starvation. Control experiments to verify non-growing conditions in the starvation regime showed that DNA and cell wall synthesis inhibitors had no inhibitory effect after 24-h starvation. The rough mutant strain displayed a lower sensitivity to a hydrophobic rather than a hydrophilic inhibitor as compared to the smooth wild-type strain. The cell size reduction but not viability was partly prevented by protein synthesis inhibitors as seen for both in vivo and in vitro colon microbiota studies.     

Reversed-phase liquid chromatographic determination of idarubicin and its 13-hydroxy metabolite in human plasma

A method is given for the determination of idarubicin and its main metabolite, idarubicinol, in plasma from cancer patients. Idarubicin and idarubicinol are extracted from 2-ml samples of buffered plasma (pH 8.1) using chloroform-1-heptanol (9:1). After reextraction into phosphoric acid (0.1 M), separation is performed by reversed-phase liquid chromatography on a LiChrosorb RP-2 column (5 μm) with a mobile phase of acetonitrile-water, acidified with phosphoric acid. The absolute recovery in the range 5–100 ng/ml was greater than 83% with a precision better than 8% (relative standard deviation), using photometric detection at 484 nm. Proper handling of whole blood samples containing idarubidin is essential to avoid metabolic conversion into idarubicinol. Prolonged storage of the drug and its main metabolite under alkaline conditions should be avoided to prevent chemical degradation.