In vitro Shoot and Root Formation in the Apple Cultivar Akero

Regulation of in vitro shoot and root formation and the histologicalorigin of newly formed shoots was studied in the apple cultivarÅkerö. Both composition of mineral elements and benzylaminopurine(BAP) concentration affected shoot multiplication. Similar numbersof shoots were obtained with Lepoivre and MS medium after twosucceeding subcultures, but Murashige and Skoog medium was preferabledue to production of longer shoots. The optimum BAP concentrationwax around 8.8 µM. Higher concentrations caused vitrifiedshoots. The rooting ability increased with numbers of subcultures.Also the concentration of indol-3-yl butyric acid (IBA) affectedrooting. A strong interaction between numbers of subculturesand IBA concentration was obtained. After insufficient numbersof subcultures, when shoots were still difficult to root, increasingIBA concentration exerted little effect on rooting. When shootshad reached an ‘easy-to-root condition’ root initiationdepended on IBA concentration, showing an optimum at 2.5 µM.Supraoptimal IBA concentrations delayed root initiation. Dark treatment of shoots during the root-initiation phase increasedrooting ability. The most positive effect was obtained at suboptimalIBA concentrations. Anatomical studies revealed both axillaryand adventitious shoots. Two kinds of adventitious structureswere demonstrated. Malus domestica Borkh. apple cultivar Åkerö, in vitro propagation, anatomy, origin of shoots     

Enzyme Activities in Urtica dioica: Effects of Daylength and Leaf Age on Glutamate Dehydrogenase, Aspartate Aminotransferase and Alanine Aminotransferase

Enzymes, important to protein synthesis, were investigated in young and old leaves of Urtica dioica. The plants, divided into two groups, were exposed to either 18-hour or 12-hour photo-periods. One group of plants from each photoperiodic regime was subjected to an irradiance of 28 W × m^-2, and the other group of plants to 42 W × m^-2. The enzymes investigated were glutamate dehydrogenase (GDH), aspartate aminotransferase (glutamate-oxaloacetate transaminase, GOT), and alanine aminotransferase (glutamate-pyruvate transaminase, GPT), GDH and GOT were determined by means of electrophoretic separation on polyacrylamide and spectrophotometric measurements. GPT was determined only by the latter method. Plants exposed to 18-hour photoperiods showed much higher GDH activity than did those exposed to 12-hour photoperiods. The activity of GDH also increased with leaf age. Besides one uniform NAD⁺-dependent GDH, two other NAD⁺-independent enzymes, showing GDH activity, were identified on polyacryl-amide gel electrophoresis. The distribution of NADH and NAD⁺-dependent GDH activity between young and old leaves was similar under different growth conditions. The activity of GOT was insensitive to environmental changes. The results regarding GPT indicate that this enzyme responded to different photoperiods in the same way as GDH. A correlation coefficient of 0.928 was obtained for the relationship between GDH and GPT activity.     

The Influence of Inorganic Ions on the Heat Stability of a Thermophilic Bacteriophage

A thermophilic bacteriophage was isolated from soil. Heat inactivation of this phage, suspended in tryptone starch broth at 65°C and 70°C, was found to be a monomolecular reaction. The phage was more heat stable in tryptone broth than in tris buffer. When the tris buffer was supplemented with calcium or magnesium ions, the survival percentage increased from 0.0 to 18.0 after two hours of heating at 65°C. The addition of sodium or potassium ions to the tris buffer had no significant effect. Equimolar solutions of calcium and magnesium chloride had the same effect on the heat stability of the phage. Maximum stability was attained in 2.5 mM solutions of these salts, and a further increase in the concentration up to 10.0 mM did not increase the percentage of surviving phages.     

Warthin''s tumour: unusual vs. common morphological findings in fine needle aspiration biopsies

Fine needle aspiration biopsies (FNA) of 47 Warthin's tumours confirmed by histology were re-evaluated for cytomorphological findings. The majority of aspirates (37/47) contained a typical background with proteinaceous substance and cell debris, along with cellular elements represented by oncocytic, lymphoid, and mast cells with degranulated cytoplasm. Uncommon cellular findings were true squamous cells (1/47), atypical cells with vacuoles (1/47), osteoclastic giant cells (1/47), epithelioid cells (1/47), mast cells with preserved granules in cytoplasm (3/47), and siderophages (4/47). Uncommon findings in the background were corpora amylacea-like structures and homogeneous bright red droplets. Squamous cells and atypical cells with vacuoles caused diagnostic difficulties in distinguishing a Warthin's tumour from a squamous cell or mucoepidermoid carcinoma. However, other unusual cellular and background findings were not worrying; therefore, they are merely regarded as a curiosity in the cytomorphological appearance of the tumour.     

The Influence of 8-Hydroxyquinoline on the Accumulation of Porphyrins in Dark-Grown Wheat Leaves Treated with δ-Aminolevulinic Acid

Dark-grown wheat leaves treated with δ-aminolevulinic acid and 8-hydroxyquinoline accumulated porphyrins, most of which were protochlorophyllide and magnesiumprotoporphyrin monomethylester. The ratio between these two components was dependent on the concentration of 8-hydroxyquinoline. Small amounts of other porphyrins could also be detected. The treatment with 8-hydroxyquinoline and the presence of large amounts of porphyrins other than protochlorophyllide did not influence the photoreduction of protochlorophyllide or the Shibata shift. 8-Hydroxyquinoline caused an inhibition of protochlorophyllide biosynthesis, which could be reversed by rinsing the leaves several times with phosphate buffer. Magnesiumprotoporphyrin monomethylester was then converted to protochlorophyllide. The reversal induced by washing was increased if the buffer contained iron. The possible function of iron in the chlorophyll metabolism and its role in the inhibition reactions with 8-hydroxyquinoline are discussed.     

Alterations of NADPH:protochlorophyllide oxidoreductase quantity and lipid composition in etiolated barley seedlings infected by Barley stripe mosaic virus (BSMV)

To understand the phenomenon by which infection of seed-transmitted Barley stripe mosaic virus (BSMV) alters membrane structures and inhibits protochlorophyllide biosynthesis of dark-grown barley ( Hordeum vulgare L.) plants, we analysed the presence of NADPH:protochlorophyllide oxidoreductase (POR, EC 1.3.1.33) and the galactolipid content and fatty acid composition. The amount of POR in etioplasts of infected leaves, compared with non-infected leaves, was reduced, as measured by immunoelectron microscopy and Western blot. These results are in agreement with the previously described reduction of the ratio of the photoactive 650 nm to non-photoactive 630 nm absorbing protochlorophyllide forms ( Harsányi et al. , 2002 . Physiol. Plant 114 , 149–155). The galactolipid content was lower in infected leaves. Monogalactosyl-diacylglycerol (MGDG) content was reduced to 40% and digalactosyl-diacylglycerol to 55% of control plants on a fresh weight basis. In infected plants, the proportion of linolenic acid decreased in both galactolipids. The lower amount of highly unsaturated fatty acids and the reduced abundance of MGDG correlated well with the previously detected reduction in the membrane ratio of prolamellar body (PLB) to prothylakoid ( Harsányi et al. , 2002 . Physiol. Plant 114 , 149–155). The reduced amount of POR and the above described alterations in the lipid composition resulted in a disturbed structure of PLBs. As a consequence, pigment synthesis and the greening process were inhibited in infected cells, in turn explaining the appearance of chlorotic stripes of BSMV-infected barley leaves. Our results show that BSMV infection can be detected at a very early stage of leaf development.     

Effect of Applied and Endogenous Auxin on Callus and Root Formation of In Vitro Shoots of the Apple: Rootstocks M26 and A2

The influence of exogenous IBA (indol-3yl-butyric acid) on rootand callus formation was studied in shoots of the apple rootstocksA2 and M26. The shoots grown in vitro were derived originallyfrom meristems of both juvenile and adult trees. Endogenousindol-3yl-acetic acid (IAA) concentrations in leaves and stemswere correlated with the responses to applied IAA. After 30 subcultures shoots from A2 and M26 rooted easily, butA2 did so more readily and even without IBA. Treatment withIBA improved percentage rooting and number of roots in bothrootstocks. Ex-adult and ex-juvenile shoots of A2 formed rootsto the same extent. However, ex-adult shoots of A2 showed ahigher IBA optimum for root number than ex-juvenile A2 and werealso less sensitive to supra-optimal IBA concentrations. Incontrast, in M26, there were no differences between ex-adultand ex-juvenile shoots. The results imply that rooting ability is associated more withdifferences between cultivars than with the origin of the explants.The best rooting occurred in ex-adult shoots of A2 which hadthe lowest endogenous IAA concentration, while callus formationwas correlated with high endogenous auxin concentration. Ex-adultA2 produced almost no callus even after exposure to high IBAconcentrations (25µM) whereas ex-adult M26 formed muchmore callus at 1/10 of the IBA concentration. Malus sylvestris (L.) Mill. var. domestica Borkh., Malus pumila Mill., apple rootstocks A2 and M26, in vitro culture, root and callus formation, HPLC analyses of IAA     

The Effect of Mercaptoethanol on the Activity of Enzymes of Nitrogen Metabolism in Leaves from Urtica dioica and Spinacia oleracea

The effect of mercaptoethanol at different concentrations on enzyme activity was investigated in leaves from Urtica dioica and Spinacia oleracea. The interference of mercaptoethanol with enzyme activity is dependent on the type of plant, the configuration of the enzyme and the concentration of mercaptoethanol. A stimulation of GDH (glutamate-dehydrogenase) was obtained in both species, while inhibition of GOT (glutamate-oxaloacetate transaminase) and GPT (glutamate-pyruvate transaminase) was demonstrated in Spinacia. The stimulation of GOT and GPT activity in Urtica was probably due to inhibition of phenol oxidase. Conclusions concerning the effect of mercaptoethanol on NR (nitrate reductase) activity were difficult to draw, since mercaptoethanol itself reduced nitrite and interfered with NR determination in tests in vitro. In Urtica. no activity could be obtained at all with the in vitro method, probably because an inhibitor of NR was liberated during the extraction procedure, Activity of NR could however be obtained in both species when using the in vivo method. Addition of protective agents to the extraction medium has been supposed to influence the protein extractability. In conformity with this increasing amount of fresh matter to the same volume of extraction medium resulted in decreased protein extractability. This led to differences in enzyme activity when expressed on a fresh weight basis but the specific activity remained constant.     

Potato proteins, and other plant proteins, as potential transgenic resistance factors to pollen beetles in oilseed rape

Proteinase inhibitors (PIs), lectin and patatin purified from potato tubers were tested in no‐choice feeding assays with pollen beetle larvae (Meligethes spp.). The idea was to search for resistance factors possible to introduce into oilseed rape (Brassica napus) by genetic engineering. The larval diet was prepared by soaking oilseed rape anthers in protein solutions of known concentrations. Potato lectin was the most potent in that it was the only of these proteins that reduced both larval survival and growth rate, while cysteine, aspartic and metallo PIs and patatin only reduced larval growth rate. Serine PIs had no significant effect on larval performance. Subsequently, the effect of potato lectin was compared to that of lectins from other food or feed crops, resulting in the following mortality‐ based ranking of activity: Con A from jackbean > wheat germ lectin > potato lectin > peanut lectin. In choice tests, larvae did not discriminate between Con A‐ and control‐diets. These results suggest that the effect of Con A on larvae is toxic, not deterrent. Adult response was stronger to Con A than to potato lectin in no‐choice tests, just as it was in larvae. However, adult survival rate and weight was not affected by Con A but the lectin significantly reduced adult feeding as well as oviposition rates. A resistance factor that suppresses adult feeding on flower buds is important for reduced impact of the pollen beetle on the Brassica oilseed crop.