No abstract

No abstract

No abstract

An ant supercolony is a very large entity with very many queens. Although normal colonies of small extent and few queens remain distinct, a supercolony is integrated harmoniously over a large area [1, 2]. The lack of aggression is advantageous: Aggression is costly, involving direct and indirect losses and recognition errors [3, 4]. Indeed, supercolonial ants are among the ecologically most successful organisms [5-7]. But how supercolonies arise remains mysterious [1, 2, 8]. Suggestions include that reduced within-colony relatedness or reduced self-nonself discrimination would foster supercolony formation [1, 2, 5, 7, 9-12]. However, one risks confusing correlation and causality in deducing the evolution from distinct colonies to supercolonies when observing established supercolonies. It might help to follow up observations of another lack of aggression, that between single-queened colonies in some ant species. We show that the single-queened Lasius austriacus lacks aggression between colonies and occasionally integrates workers across colonies but maintains high within-colony relatedness and self-nonself discrimination. Provided that the ecological framework permits, reduced aggression might prove adaptive for any ant colony irrespective of within-colony relatedness. Abandoning aggression while maintaining discrimination might be a first stage in supercolony formation. This adds to the emphasis of ecology as central to the evolution of cooperation in general [13].

The wax ester fractions of solvent-extracted sunflower oil and "extra virgin" olive oil were obtained by solidphase extraction and subsequently subjected to gas-chromatographic and gas chromatographic-mass spectrometric analysis. The comprehensive qualitative analysis of these fractions, which was carried out by the interpretation of mass spectral data, revealed several types of wax esters. In olive oil, shortchain, even-numbered wax esters, saturated and unsaturated long-chain, even-numbered wax esters, benzyl esters, and the diterpenic esters phytyl and geranylgeranyl ester (the latter as a minor component) are present. With the exception of benzyl esters, all these esters occur in sunflower oil as well, but in considerably different amounts compared to those in olive oil. Whereas unsaturated wax esters are present in a negligible amount, diterpenic esters, mainly geranylgeranyl esters, represent the major part of the wax ester fraction.Paper no. J9809 in JAOCS 78, 881-888 (September 2001) Wax esters (WE) are part of the unsaponifiable matter in vegetable oils and are of interest to the oil-processing industry for various reasons. The WE content is used as a quality parameter for high-quality oils such as cold-pressed "extra virgin" olive oils (1). For instance, the European Union Regulation No. 183/93 requires the quantitation of WE in olive oils, because solvent-extracted olive oils contain a considerably higher amount of waxes than oils obtained by cold pressing (2). In addition, typical WE patterns or specific WE enable the recognition of adulteration of high-quality oils with cheaper oils, for example, the addition of sunflower oil to olive oil (3). The isolation of WE in vegetable oils has been performed by on-line high-performance liquid chromatography-gas chromatography (HPLC-GC) (3-6), by column chromatography (7), by HPLC (8,9), and, recently, by solid-phase extraction (SPE) (10,11) with subsequent capillary GC analysis. None of these techniques requires saponification of the WE fraction. Therefore, WE can be determined without any alteration of their structure. These analytical methods allow isolation and quantitation of WE according to their number of carbon atoms and their degree of unsaturation, but a complete qualitative analysis as well as elucidation of isomeric constitution can only be carried out by mass spectrometric (MS) methods.WE in olive and sunflower oils are of particular interest, as already mentioned, but there is a lack of data concerning their detailed structures and their isomeric composition. In the case of olive oil, a GC-MS analysis of WE in extracted olive oil published by Bianchi et al. (12) revealed the presence of esters with alcohols (AL) in the range of AL 1-AL 6, esters of oleic acid with long-chain aliphatic alcohols AL 22-AL 38, and benzyl alcohol esters of the long-chain saturated fatty acids (FA) FA 26 and FA 28.The composition of sunflower WE has been determined only by the analysis of hydrolysis products. WE were hydrolyzed, and fatty acids and alcohols were an...

No abstract

No abstract

SummaryVegetable oil methyl esters are increasingly being used as substitutes for petroleum-based diesel fuels. Because the presence of triglycerides and partial glycerides in the fuel as a result of incomplete transesterification of vegetable oils can lead to serious engine problems, continuous quality control of the product is essential. A rapid gas chromatographic method has been developed for the quantitative determination of mono-, di-, and triglycerides in vegetable oil methyl esters.Prior to analysis, mono-, and diglycerides were silylated with N,O-bis(trimethylsilyl)trifluoroacetamide; tridecanoin was used as internal standard. Calibration was performed by analysis of standard solutions containing mono-, di-, and triolein: the calibration plots for mono-and diglycerides showed good linearity, whereas for triglycerides no linearity was observed for triolein concentrations below 0.05 mg/ml. When a non-linear multi level calibration was employed for the quantitation of triglycerides, the method gave excellent quantitative results for mono-, di-, and triglycerides in vegetable oil methyl esters. fntroductionVegetable oil methyl esters, obtained by alkali-catalyzed transesterification of vegetable oils with methanol, are used as substitutes for petroleum-based diesel fuels on an increasing scale both in Europe and elsewhere 11-31, At present, three small plants in Austria are each producing 500 t rapeseed oil methyl ester (RME) per year. One commercial plant producing 10000 t/a is in operation and another with a capacity of 15000 t RME per year is under construction.Since incomplete transesterification of vegetable oils can lead to significant contamination of the vegetable oil methyl esters with mono-, di-, and triglycerides, continuous quality control of the product is essential. Long-term engine tests have shown that the presence of triglycerides and partial glycerides in the fuel causes serious problems through formation of engine deposits. carboiiization of the injection nozzle, piston, and valves, and formation of sludge in the lubrication system have been reported [I]. The incomplete combustion of glycerides also leads to the formation and emission of hazardous acrolein, derived from glycerol Ill. In Austria, a limit to the permissible levels of mono-, di-, and triglycerides in RME fuel has therefore been introduced by the standard ONORM C 1190, and specialized analytical methods for the quantitative determination of mono-, di-, and triglycerides in vegetable oil methyl esters had to be developed 141In recent years, increasing use has been made of capillary gas chromatography (CGC) for the analysis of triglycerides or complex mixtures containing triglycerides 15-91. The quantitation of triglycerides has been extensively studied with special regard to the effects of experimental conditions including sample injection technique, carrier gas flow-rate, and temperature programming [ 10-151. The dependence of the recovery of the compounds on the amount, structure, and molecular weight of triglycerides has als...