Growth and reproduction of aphids and levels of free amino acids in Scots pine and Norway spruce in an open-air fumigation with ozone

To estimate the susceptibility of conifer seedlings to aphids under future tropospheric ozone levels, Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) seedlings were exposed to ambient and elevated ozone levels in an open-air exposure system. Growth and reproduction of the aphids Schizolachnus pineti and Cinara pinea on Scots pine and Cinara pilicornis on Norway spruce were monitored. Levels of free amino acids in foliage and young shoots were used as indicators of host plant quality. In elevated treatment plots the ozone doses were between 1.2 and 1.7 times the dose in ambient plots in 1990–93. Half of the seedling material in 1992–93 was subjected to nitrogen fertilization treatment to evaluate the effects of increased N deposition. In 1990, population density of S. pineti on pine did not differ between ambient and elevated ozone treatments during growing season, but remained higher in the elevated ozone plot than in the ambient plot at the end of the growing season. This was associated with elevated levels of glutamic acid in foliage. In August 1992, the numbers of S. pineti were consistent between the two ambient ozone plots, but deviated highly between the two ozone-fumigated plots. Glycine concentration in pine foliage was elevated by ozone, but free amino acid concentrations were not related to aphid performance. In 1993, ozone and nitrogen did not significantly affect the relative growth rate (RGR) of S. pineti or C. pinea nymphs on Scots pine, but glutamic acid concentration in foliage was increased by nitrogen fertilization. On Norway spruce, fecundity of C. pilicornis females was higher in elevated ozone treatment, but RGR of nymphs was not affected in 1992. In 1993, RGR of C. pilicornis nymphs was increased by nitrogen fertilization in June, but not affected by ozone. Nitrogen fertilization increased the levels of total free amino acids, aspartic acid, glutamic acid and proline in elongating shoots of Norway spruce, and ozone reduced the concentrations of valine and γ-butyric acid. Our results suggest that availability of nitrogen from soil has a stronger impact on the concentrations of free amino acids in conifer seedlings than ozone. Some episodes of high ozone concentration may increase free amino acids in foliage. Aphid response to ozone was extremely variable, in agreement with previous laboratory experiments. The expected 20–70% increase in ambient concentrations of tropospheric ozone may in some occasions enhance aphid performance on Scots pine and Norway spruce seedlings, but in most cases the ozone effect on the susceptibility of conifer seedlings to sucking insect pests is not important.     

THE EFFECT OF INFORMATION RELATED TO FAT CONTENT AND TASTE ON CONSUMER RESPONSES TO A REDUCED-FAT FRANKFURTER AND A REDUCED-FAT CHOCOLATE BAR

The effects of product information on responses to frankfurter sausages and chocolate bars were studied by comparing sensory and hedonic ratings in two conditions: blind tasting and tasting with information present. Furthermore, the effect of information alone was investigated by having the subjects rate the expected sensory and hedonic intensities of the products on the basis of packages with different claims. Three groups of subjects were tested by giving them different information: The basic group (no added claims, n=31), the reduced-fat group (products claimed to have reduced-fat, n=29) and the flavorful group (products claimed to have full meat/chocolate flavor, n=31). Product information increased the rated pleasantness of the frankfurter in all three information groups compared to the blind ratings. The information did not affect the pleasantness of the chocolate bars. The expected attribute intensities of the frankfurters and chocolates were rated lower by the reduced-fat group than by the other groups. Overall, the effect of product information was more clearly seen in ratings of sensory attributes than in pleasantness ratings.     

Fatty Acid Composition of Polar Lipids in Ceratodon purpureus and Pleurozium schreberi

The total amount of fatty acids in the mono- (MGDG) and diglycosyl diglyceride (DGDG) and more polar lipid fractions of frozen Ceratodon purpureus shoots was 4.6, 3.4 and 4.0 mg/g dry weight, respectively. The respective values for the tops of frozen Pleurozium schreberi were 2.6, 3.3 and 3.8 mg/g dry weight. The molar ratios MGDG/DGDG and MGDG + DGDG/chlorophyll were 1.3 and 3.7, respectively, for C. purpureus and 0.8 and 3.5 for P. schreberi. In C. purpureus the main fatty acids in the MGDG fraction were C 18:3ω3 (44% of the total fatty acids) and C 16:3ω3 (26%); in the DGDG fraction C 18:3ω3 (70%); and in the more polar lipid fraction C 18: 3ω3 (26%) and C 16:0 (25%). The proportion of C 20 polyunsaturated fatty acids was 15, 12 and 19% of the total fatty acids found in the MGDG, DGDG and more polar lipid fractions, respectively. In P. schreberi the proportion of C 20 polyunsaturated fatty acids was high in all polar lipid fractions (47, 42 and 25% in MGDG, DGDG and more polar lipid fractions, respectively). In addition, MGDG and DGDG fractions contained abundantly C 18:3ω3 (32 and 45%, respectively), and the more polar lipid fraction both C 18: 3ω3 (24%) and C 16:0 (27%).     

Changes in the Content of Phytyl and Geranylgeranyl Esters of Germinating Polytrichum commune Spores

Polytrichum commune spores contained esterified phytol and geranylgeraniol, 706 and 114 μg, respectively, per 100 mg dry weight of freshly collected spores. After storage for 9 months the level of esterified phytol of the spores was decreased by c. 600 μg, whereas the level of esterified geranylgeraniol was more or less unchanged. The changes in the level of esterified prenols during germination follow the same pattern in freshly collected and in 9 month-old spore material. An immediate steep decrease between 0 and 3 h was followed by an increase in the level of esterified phytol between 3 and 12 h and by a constant value for esterified geranylgeraniol during the same period. Between 12 and 48 h the level of both types of esterified prenols decreased. In the freshly collected spores the amount of esterified prenols increased after 48 h of germination, in the older spores after 72 h. Free phytol was found in trace amounts in dry and germinating spores and in the protonema.     

Influence of S-ethyl Dipropylthiocarbamate (EPTC) on the Fatty Acid Composition of Wheat Leaf Galactolipids

Winter wheat (Triticum sativum L. cv. Nisu) was grown in sand which contained 0, 0.25, 0.5 and 1.0 mg S-ethyl dipropylthiocarbamate (EPTC) per kg air dry sand. The galactolipids of leaves of 21-day-old seedlings were isolated by preparative thin layer chromatography. The fatty acids of the mono- and digalactosyl diglycerides were analysed by gas liquid capillary chromatography. The major fatty acids of the wheat leaf galactolipids were palmitic, palmitoleic, stearic, oleic, vaccenic, linoleic and linolenic acids (in the monogalactosyl diglyceride fraction of untreated plants 22.5, 2.4, 3.1, 5.2, 2.5, 51.1 and 1526.6 μg and in the digalactosyl diglyceride fraction 108.8, 2.3, 10.4, 9.9, 8.2, 42.3 and 1120.7 μg/g leaf fresh weight, respectively). Total fatty acid content of the mono- and digalactosyl diglyceride fractions was decreased by 85 and 87%, respectively, at 1 mg EPTC/kg sand, while decrease in the fresh weight of the leaves was 79%. The content of linoleic and linolenic acids/g fresh weight of the leaves was decreased in the monogalactosyl diglyceride fraction by 27 and 43%, respectively, while the content of all other fatty acids was increased. In the digalactosyl diglyceride fraction the content of both linoleic and linolenic acids/g leaf fresh weight was decreased by 55%. The content of palmitic and vaccenic acids was also decreased, whereas the content of other fatty acids remained at the level of the untreated samples. The general quality of the fatty acids in the mono- and digalactosyl diglyceride fractions was altered slightly by EPTC.     

Determination of Fatty Acid Composition of Spore Lipids of the Moss Polytrichum commune by Glass Capillary Column Gas Chromatography

Fatty acid methyl esters of Polytrichum commune spore triglyceride and mono- and diglycosyl diglyceride fractions were analysed by glass capillary column gas chromatography provided with a precolumn system. The composition of the fatty acids in the lipid fractions differed only quantitatively: the diglycosyl diglyceride fraction was characterized by a high content of C 18: 3ω3 (67.7%), and the triglyceride and monoglycosyl diglyceride fractions by about 35%. The monoglycosyl diglyceride fraction contained a high proportion of C 14: 0 (18.4%). In all fractions the content of polyunsaturated C 20 acids was low, ranging from trace amounts to 4.9%.     

Influence of S-ethyl dipropylthiocarbamate (EPTC) on Wheat Root Phospholipid Fatty Acid Composition

Winter wheat (Triticum sativum L. ev. Nisu) was grown in sand which contained 0, 0.25, 0.5 and 1.0 mg S-ethyl dipropylthicarbamate (EPTC) per kg air dry sand. In 21 day old roots, the phospholipids (PL) were extracted in ice-cold chloroform/methanol (2:1, v/v) and isolated by thin layer chromatography (TLC). The PL fatty acids were analysed by gas liquid chromatography (GLC). The major fatty acids of the root PL fraction were palmitic, oletic, linoleic, and linolenic (22.4, 6.8, 39.2, and 23.1 μ/g root fresh weight, respectively). Total fatty acid content of the PL fraction was decreased to 39% by 1 mg EPTC/kg sand in which linolenic acid was decreased to 28%. The remainder of the major fatty acid constituents were decreased to 12–47%. The general quality of fatty acids in the PL fraction was slightly altered, while a 60% inhibition of total PL production resulted.     

Determination of Prenylquinones in Green Photosynthetically Active Moss and Liver Moss Tissues

The prenylquinone composition of two species of mosses (Polytrichum formosum Hedw., Sphagnum acutifolium Ehrh.) and two species of liver mosses (Lunularia cruciata (L.) Dum., Pellia epiphylla (L.) Cord.) was determined and compared with the chlorophyll content and the photosynthetic activity of the intact moss and liver moss tissues.

• 1 Green moss and liver moss tissues possess in principle the same prenylquinone composition as higher plants with plastoquinone-9, α-tocopherol, α-tocoquinone and the phylloquinone K₁ as main components. On a chlorophyll basis the lipoquinone levels are lower than in higher plants. Differences among the individual mosses as well as within one species only occur in the quantitative levels of the chloroplast prenylquinones, but there are no differences between musci and liver mosses.
• 2 There are differences in the maximal fluorescence of liver mosses and mosses. The variable fluorescence in turn, which is a measure of in vivo photosynthetic activity, is very similar for all examined species of mosses and liver mosses (values from 0.7 to 1.0) but somewhat lower than in leaf pieces of higher plants. DCMU blocks the variable fluorescence and the concomitant oxygen evolution in all mosses and liver mosses.
• 3 From the lower prenylquinone levels and the low values for the variable fluorescence it is concluded that mosses and liver mosses exhibit on a chlorophyll basis fewer reaction centres and electron transport chains than chloroplasts of higher plants.

     

Occurrence of steryl and wax esters in Dicranum elongatum

The steryl and wax esters of the frozen subarctic moss Dicranum elongatum Schleich contained fatty acids 39.8 mg per gram dry green tissue. The content decreased with increasing age of the moss shoots, but no great changes were found in the fatty acid pattern of the esters. The major part of the steryl and wax ester fraction of the green shoots was made up of esterified sterols (85%), and the rest (15%) of esterified aliphatic alcohols. No great changes were found in their relative proportions with increased age of the shoots. Some changes were evident in the pattern of individual esterified sterols, however. The proportion of cycloartenol was lower in the older parts than in the green part, and the proportion of campesterol, stigmasterol, and β-sitosterol were lower in the green part. The major esterified aliphatic alcohols were 1-octadecanol, phytol and geranylgeraniol. The proportion of geranylgeraniol was highest in the green part and that of phytol in the older parts. The main alcohol of the surface lipids was 1-octadecanol.