Metabolic rates of vascular endothelial cellsin vitro

Cultures of endothelial cells and cell lines of endothelial origin were maintained at confluence without medium exchange for a period of 72 h. During this time period the concentration of nutrients — amino acids and glucose — and metabolic waste products — lactate and ammonium — was determined as well as cell vitality and cell numbers. Metabolic rates were calculated and compared for the different cell lines. Surprisingly the primary cells showed significantly higher rates of glucose and glutamine consumption, respectively lactate production than the immortalized cell lines. Except for one tumorigenic cell line all cells showed a significant participation of transaminases in glutamine/ammonium metabolism. Furthermore it could be shown that in routine culture there was no depletion of nutrients or critical accumulation of ammonium or lactate over a culture period of 72 h.Abbreviations BAEC bovine aorta endothelial cells - EC vascular endothelial cells - FGF fibroblast growth factor - HUVEC vascular endothelial cells from human umbilical cord veins - IF 1:1 mixture of Iscove's MDM and Ham's F12 basal media - MTT 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromid - NCS newborn calf serum - PBS phosphate buffered saline - TE 0.05% (w/V) trypsin, 0.02% (w/v) EDTA in PBS     

Resource quality and spatial variation in sex ratios of a free-living solitary sawfly,Dineura virididorsata (Hym., Tenthredinidae)

The sex ratio in final-instar larvae of a birch-feeding, free-living solitary sawfly, Dineura virididorsata, was investigated in Finnish Lapland. The prepupal proportion of females, pooled over ten sites, was 56%, and at four individual sites the sex ratio was significantly female-biased. Larval survival from egg to prepupae did not differ between the sexes. This suggests a femalebiased primary sex ratio in the field. The sex ratio varied among the sites but not among host trees within sites. Contrary to previous results with hymenopterans, we did not find that differences in the sex ratio depended on forage quality: site-specific or tree-specific sex ratios did not correlate with the average prepupal weight. A literature search indicated that female-biased sex ratios are also common in other free-living sawflies. We are unable to explain sex ratios of Dineura virididorsata or other free-living sawflies with existing general models.     

Egg and larval load assessment and its influence on oviposition behaviour of the leaf beetle Galerucella nymphaeae

The oviposition behaviour of the water-lily beetle Galerucella nymphaeae was examined. This species is a specialist herbivore on the floating leaves of nymphaeids Nymphaeaceae and especially on the yellow water-lily, Nuphar lutea. Females lay their eggs in clutches on the leaves, and after hatching, the larvae feed on the leaves. The quality of the leaves decreases quickly after the larvae hatch, and eventually the leaves will sink below the water surface, whereupon the eggs, 1st-instar larvae and pupae are killed by drowning. The influence of conspecific eggs, larvae and feeding tracks on the oviposition preferences of the beetles was tested. Females were allowed to choose between fresh leaves and leaves with conspecific eggs and larvae as well as between leaves with larvae and leaves with feeding tracks but no larvae. An attempt was also made to determine whether eggs and larvae affect the oviposition rate of females when they are not given the opportunity to oviposit on untouched leaves. The results indicate that females tended to avoid leaves with conspecific larvae or to exhibit a decreased oviposition rate on such leaves. Females also avoided conspecific eggs, although the oviposition rate was not influenced by the presence of conspecific eggs. When females were allowed to choose between leaves with larvae and leaves with feeding tracks, possible discrimination against leaves with larvae just fails to reach the 5% level.     

Studies of 13C in the foliage reveal interactions between nutrients and water in forest fertilization experiments

The severity of a root rot disease of cereals, caused by Rhizoctonia solani Kühn AG8, was inversely correlated to the Zn status of plants in field studies in 1989 and 1990. In 1989, a preliminary survey was conducted in a farmer's field in South Australia where Zn deficiency and disease were both widespread. Zn concentration in Spear wheat plants at the 3-leaf to early tillering stage was negatively correlated with severity of the disease. For the elevent elements analysed, a correlation matrix showed that Zn had the highest, and only significant (R²=0.52^**) association with disease. The effect of Zn applications and their residual value on disease severity was further studied in a long-term field experiment in 1989 and 1990 to which Zn had been applied in 1986. There was a decrease in the area of Rhizoctonia bare patch as Zn rate was increased, a result consistent with the field survey results; the recommended rate of 2.5 kg Zn ha^–1 reduced the area affected by bare patch from 42% to 21% of the total crop area compared with no Zn application, overcame Zn deficiency and increased grain yield from 1.1 to 2.8 t ha^–1. In 1990, fresh Zn application treatments were applied to trial plots designed for this purpose, in order to compare the response with the older Zn treatments applied in 1986. The areas of bare patch in the older Zn treatments were approximately 5% greater than those in the fresh Zn treatments. The results are consistent with the hypothesis that Zn deficient plants are more susceptible to root rot caused by R. solani. Testing this hypothesis is the subject of a companion paper.     

Flight metabolism in the African fruit beetle,Pachnoda sinuata

Metabolite concentrations in flight muscles and in abdomen of beetles (Pachnoda sinuata) were measured after various periods of tethered flight and subsequent rest. Three distinct phases of energy metabolism are found in active flight muscles: (1) during the first minutes of flight proline is used as main substrate and concomitantly alanine accumulated as an end product; (2) the second phase is characterized by a large-scale degradation of glycogen; (3) after about 8 min of flight the metabolite levels stabilize, while flight performance appears unchanged. After the termination of flight the preflight proline concentration (70 mol·g^-1 fw) is re-established in less than 60 min, whereas restoration of resting levels of other metabolites requires longer. The pattern of maximal enzyme activities and the respiratory rates of mitochondria with different substrates confirm the significance of proline and carbohydrates as the main fuels of working flight muscles.Abbreviations CS citrate synthetase - Cytox cytochrome c oxidase - EDTA ethylenediaminetetra-acetate - fw fresh weight - GluDH glutamate dehydrogenase - GPT alanine aminotransferase - HOAD hydroxyacyl-coenzyme A dehydrogenase - HPLC high pressure liquid chromatography - ME malic enzyme - PCA perchloric acid - RQ repiratory quotient - TRA triethanolamine     

Enzymatic hydrolosis of isolated and fibre-bound galactoglucomannans from pine-wood and pine kraft pulp

Fibre-bound and isolated galactoglumanans from pine-wood and pine kraft pulp were hydrolysed with purified mannanases from Trichoderma reesei and Bacillus subtilis. The isolated galactoglucomannans from both wood and pulp could be hydrolysed fairly extensively with both enzymes. In addition to mixed oligomers, the fungal mannase produced mannobiose as the main hydrolysis product whereas the bacterial mannanase produced mannobiose, mannotriose and mannotetraose. Both enzymes hydrolysed the native galactoglucomannan in finely ground pinewood, whereas galactoglucomannan in pine kraft pulp was only hydrolysed by the T. ressei mannanase. Thus, mannanases exhibit different specificities on fibre-bound, modified substrates. In spite of the high enzyme loading, the degree of hydrolysis of fibre-bound substrates did not exceed 10% of the theoretical, probably due to poor accessibility of the substrates. Correspondence to: M. Rättö     

Simulation of phototaxis in the flagellateEuglena gracilis

A three-dimensional model of the flagellateEuglena gracilis was developed to simulate phototaxis and movement in space. The simulation of the phototactic behavior was compared with thein vivo behavior in order to determine the mechanism of orientation with respect to light. Phototactic behavior with respect to one light source, can be explained by the shading hypothesis as well as by a dichroic orientation of the absorbing vectors of the photoreceptor pigments. In contrast, the behavior of the cells when exposed to two perpendicular light beams is not compatible with the shading hypothesis. Likewise, the phototactic orientation of stigmaless cells cannot be accounted for on the basis of the shading hypothesis. In contrast, simulations andin vivo observations of the behavior under polarized light strongly indicate the validity of the dichroic orientation of the photoreceptor pigments.     

Different genomic structure of mouse and human Lmp7 genes: characterization of MHC-encoded proteasome genes

The nucleotide sequence data reported in this paper have been submitted to the GenBank nucleotide sequence database and have been assigned the accession numbers L11045 (human LMP7) and L11145 (mouse Lmp-7).     

Cloning of cDNA coding for dihydroflavonol-4-reductase (DFR) and characterization of dfr expression in the corollas of Gerbera hybrida var. Regina (Compositae)

We are approaching corolla differentiation in Compositae by studying the regulation of flavonoid pathway genes during inflorescence development in gerbera. We have cloned a dfr cDNA from a ray floret corolla cDNA library of Gerbera hybrida var. Regina by a PCR technique based on homologies found in genes isolated from other plant species. The functionality of the clone was tested in vivo by complementing the dihydrokaempferol accumulating petunia mutant line RL01. By Southern blot analysis, G. hybrida var. Regina was shown to harbour a small family of dfr genes, one member of which was deduced to be mainly responsible for the DFR activity in corolla. Dfr expression in corolla correlates with the anthocyanin accumulation pattern: it is basipetally induced, epidermally specific and restricted to the ligular part of corolla. By comparing the dfr expression in different floret types during inflorescence development, we could see that dfr expression reflects developmental schemes of the outermost ray and trans florets, contrasted with that of the disc florets.     

Nutrient-split feeding strategy for dialysis cultivation of Escherichia coli

Reduction in nutrient loss during dialysis cultivation of Escherichia coli on a glycerol medium was investigated. A dialysis reactor with an inner fermentation and an outer dialysis chamber was used. Aerobic condition was maintained by limiting the glycerol feed rate to an optimum value which was estimated from the oxygen requirements for glycerol oxidation and oxygen transfer capacity of the reactor. High reduction in nutrient loss was achieved by using water as the dialyzing fluid. However, osmotic movement of water from the dialysis to the fermentation chamber was observed, and the final cell concentration was low. With a nutrient-split feeding strategy (feeding glycerol directly to the fermentation chamber and dialyzing with salt solution), glycerol loss was small, there was no osmotic flux of water to the fermentation chamber, and the cell concentration was high. Both glycerol and salt loss could be avoided, and a cell concentration of 170 g/L was obtained when the dialysis process was substituted by addition of XAD adsorbents to the dialysis chamber. Application of this nutrient-split feeding strategy to cell cultivation in a stirred tank reactor, coupled with dialysis in external dialyzer modules, resulted in low cell concentrations. (c) 1993 Wiley & Sons, Inc.