Comparison of gas chromatography-mass spectrometry,radioimmunoassay and bioassay for the quantification of gibberellin A9 in norway spruce (Picea abies (L.) Karst.)

Quantitative estimates of gibberellin A₉ in Norway spruce extracts obtained by gas chromatography-mass spectrometry, radioimmunoassay (RIA_ and bioassay were compared after successive purifications of the extracts. The extracts were assayed in several dilutions with and without the addition of standard gibberellin A₉, thus showing the effect of extract components on the response of the assays. Radioimmunoassay produced estimates comparable to gas chromatography-mass spectrometry after one purification step by high-performance liquid chromatography. Extracts purified by polyvinylpyrrolidone-column chromatography and solvent partitioning but not high-performance liquid chromatography resulted in inaccurate RIA estimates. The performance of the RIA could be monitored by logit-log transformations of the standard curve and extract dilution curve and by calculating the slope of the standard addition curve. It was, however, not possible to correct for the interference caused by extract components by the standard addition procedure. Quantifications by Tan-ginbozu dwarf-rice bioassay were accurate, but a large and unpredictable variation makes it unsuitable for quantitative determinations.Abbreviations FW fresh weight - GA₉ gibberellin A₉ - GA₉–Me methylated GA₉ - GC-MS gas chromatography-mass spectrometry - HPLC high performance liquid chromatography - MID multiple-ion detection - RIA radioimmunoassay     

NAD(P)H oxidase and peroxidase activities in purified plasma membranes from cauliflower inflorescences

An NAD(P)H oxidase activity stimulated by phenolic compounds has been investigated in purified plasma membranes (pm) and in an intracellular membrane (icm) fraction depleted in plasma membranes, both obtained from a microsomal fraction from cauliflower inflorescences ( Brassica oleracea L.). The phenolic compounds salicylhydroxamic acid (SHAM), ferulic acid, coniferyl alcohol, n -propyl gallate, naringenin, kaempferol and caffeic acid all strongly stimulated the activity. Peroxidase (EC 1.11.1.7), or a peroxidase-like enzyme, was responsible for the NAD(P)H oxidase activity, which proceeded through a free-radical chain reaction and was inhibited by catalase (EC 1.11.1.6), superoxide dismutase (EC 1.15.1.1) and KCN. Most of the total activity was soluble; however, the membrane-bound activity was highly enriched in the pm compared to the icm. The catalase activity was 6 times higher in the icm-fraction than in the pm-fraction, but this was not the reason for the much lower phenol-stimulated NADH oxidase activity in the icm. Peroxidase activity measured with o -dianisidine and H₂O₂ had about the same specific activities in the pm-and icm-fractions.
Neither the phenol-stimulated NADH oxidase nor the peroxidase activity could be washed away from the pm even by 0.7 M NaCl, indicating that these activities are truly membrane-bound. SHAM as well as the other phenolic compounds capable of stimulating the NADH oxidase reaction were potent inhibitors of blue light-induced cytochrome b -reduction in the pm fraction.     

Goshawk predation during winter, spring and summer in a boreal forest area of central Sweden

Predation by goshawks was studied in a central Swedish boreal forest area. Data were collected in winter (January–February) 1977-81 by tracking radio-tagged goshawks, and in the breeding season (April–July) by collecting prey remains at the nest. In the breeding season birds dominated the prey, amounting to 86% of prey number and 91% of prey biomass. Wood pigeon Columba palumbus , black grouse Tetrao tetrix , hooded crow Corvus corone cornix and jay Garrulus glandarius accounted for more than 50% of the prey animals, whereas capercaillie Tetrao urogallus and black grouse accounted for more than 50% of prey biomass. There was no functional response to black grouse density fluctuations. Every year goshawks killed significantly more females than males of both capercaillie and black grouse, due to high vulnerability of the grouse hens while laying and incubating. It was estimated that during spring and early summer goshawk predation removed 25% of the female, and 14% of the male black grouse population. In winter squirrel was the dominating prey, both in terms of number (79%) and weight (56%). The proportion of squirrel in the diet was equally high both in winters of low and high squirrel density. The high proportion of squirrel in the winterdiet, as compared to the breeding season, is believed to be due to squirrels having to accept an increased predation risk in winter, in order to feed efficiently enough.     

Filtration rate capacities in 6 species of European freshwater bivalves

Summary Filtration rate capacities in undisturbed freshwater bivalves were determined by means of two different methods (indirect clearance and suction methods) in Anodonta anatina (L.), Unio tumidus Philipsson, Unio pictorum (L.), Unio crassus Philipsson, Dreissena polymorpha (Pallas) and Sphaerium corneum (L.). In A. anatina, D. polymorpha, and S. corneum the filtration rate (FR, 1 h^-1) at 19–20°C as a function of dry tissue weight (DW, g) or ash-free dry weight (AFDW, g) could be expressed by the equations: 1.10 DW^0.78, 6.82 DW^0.88, and 2.14 AFDW^0.92, respectively. In U. tumidus, U. pictorum, and U. crassus filtration rates were comparable with those of A. anatina. In D. polymorpha the b value of the corresponding regression of gill area on dry weight was 0.87. The rates of water transport in freshwater bivalves are 2–8 times lower than in marine bivalves of comparable size. A corresponding difference in the filtration rate per gill area unit is found. The measured filtration rates in undisturbed bivalves are substantially higher (at least 4 times) than previously reported. This indicates that the impact of bivalve water processing on freshwater ecosystems is greater than hitherto suggested.     

Dose responses of gibberellins

To determine the response type, published data for the most widely used bioassays for gibberellins have been analyzed by means of a computer program for estimating sensitivity parameters, or by interpolation. The dose response data are almost uniformly subsensitive, i. e. more than an 81-fold increase in external gibberellin concentration is required for a change from 10 to 90% of maximal response (S₉₀/S₁₀). Data for the interaction of gibberellins with artificial membranes are, in contrast, markedly ultrasensitive (S₉₀/S₁₀± 10). This difference further strengthens the view that lipid structures do not function as receptors for gibberellins. Most of the subsensitive dose responses for gibberellins can be quite precisely represented by cooperative isotherms. However, available data are insufficiently detailed for an unequivocal choice among cooperative, multiphasic or more complex kinetics.     

Behaviour of drifting insect larvae

The larval drift behaviour of 23 species representing Ephemeroptera, Plecoptera and Trichoptera was investigated in the laboratory using different current regimes. Mayfly nymphs often performed swimming, while caddis larvae were reluctant to do so. Stonefly nymphs were intermediate. In mayflies swimming seemed to be used to reach the substrate as soon as possible. In contrast most stonefly nymphs by swimming prolonged the time spent in the water column. Modes of swimming and sinking posture differed markedly between the orders. Living passively sinking animals often reached bottom faster than dead control specimens, so consequently behaviour did not always express itself in activity. Some caddis larvae spun adherent anchor lines. Differences among taxa seemed more important in explaining swimming activity compared to preferred habitats (as stream, river and lake) in each species. However, observed differences among closely related species indicated subtle differences related to microhabitat to be of profound importance in explaining the alternative behavioural strategies used.     

Cell cycle traverse and protein metabolism in human NHIK 3025 cells: the role of anchorage

We have studied the effect of cell anchorage on the human cell line NHIK 3025 in vitro, to see whether the growth regulating effect of cell anchorage primarily affected DNA division cycle or mass growth cycle. It was found that cell to cell anchorage had the same effect on cell cycle progression as anchorage to a solid surface, which indicates that it is anchorage per se and not cell shape that is important for growth control in NHIK 3025 cells. When NHIK 3025 cells were grown without attachment to a solid surface, both G1 and cell cycle duration was prolonged by 6 h, which means that the prolonged cell cycle was due to a prolonged G1. During the first part of the cell cycle the rate of protein synthesis and degradation was constant, and at the same level in cells grown with and without attachment. This means that the prolonged G1 was not due to a reduced protein accumulation or mass growth. Towards the end of the cell cycle protein accumulation was reduced. This effect was either due to a size control before cell division or a secondary effect of the prolonged G1. We therefore conclude that cell anchorage as a growth regulator primarily affects the DNA/cell division cycle.     

Single-file diffusion through the Ca2+-activated K+ channel of human red cells

Summary We have examined the effect of internal and external pH on Na⁺ transport across toad bladder membrane vesicles. Vesicles prepared and assayed with a recently modified procedure (Garty & Asher, 1985) exhibit large, rheogenic, amiloridesensitive fluxes. Of the total²²Na uptake measured 0.5–2.0 min after introducing tracer, 80±4% (mean±se,n=9) is blocked by the diuretic with aK ₁ of 2×10^–8 m. Thus, this amiloridesensitive flux is mediated by the apical sodium-selective channels. Varying the internal (cytosolic) pH over the physiologic range 7.0–8.0 had no effect on sodium transport; this result suggests that variation of intracellular pHin vivo has no direct apical effect on modulating sodium uptake. On the other hand,²²Na was directly and monotonically dependent on external pH. External acidification also reduced the amiloride-sensitive efflux across the walls of the vesicles. This inhibition of²²Na efflux was noted at external Na⁺ concentrations of both 0.2 m and 53mm.These results are different from those reported with whole toad bladder. A number of possible bases for these differences are considered and discussed. We suggest that the natriferic response induced by mucosal acidification of whole toad urinary bladder appears to operate indirectly through one or more factors, presumably cytosolic, present in whole cells and absent from the vesicles.