The effect of selected seed oils on the fatty acid composition and growth of Penaeus indicus

Various seed oils included in artificial diets for Penaeus indicus were examined for their influence on weight gain and tissue lipid composition. Four seed oils were selected on the basis of known differences in their fatty acid compositions, principally those essential fatty acids of the linolenic (ω3), linoleic (ω6) and oleic (ω9) type series. A 35-day feeding trial showed no significant growth differences between prawns fed either sunflower, linseed, soybean or groundnut oil at a 5% level of inclusion. Proximate carcass analyses on the experimental animals indicated an increase in depot lipid in comparison to equivalent wild caught prawn.The component fatty acids of total lipid extracts from the fed prawns showed a significant degree of correlation with those of the dietary lipid intake. In particular, high tissue depot levels of linoleic acid (18: 2ω6) were associated with all seed oil diets. This may be compared with similar analyses on wild caught prawns in which a higher degree of lipid unsaturation was attained by proportionate increase in the longer chain homologues (>C₂₀ chain length) of the ω3 and ω6-type fatty acids. Under present dietary regimes, therefore, there appears to be limited capacity for biosynthetic interconversion of essential fatty acids to longer chain polyunsaturates of the same typed series. Related experience in fish nutrition suggests that precise dietary levels and a balanced ratio of $\text{ω3}\text{ω6}\text{-}\text{type}$ fatty acid may be necessary for efficient lipid metabolism.     

Potato flakes. A new form of dehydrated mashed potatoes

American Journal of Potato Research -     

Evaluation of liquid chromatographic methods for analysis of chlorphoxim formulations

Liquid chromatographic (LC) methods for determination of active ingredient in chlorphoxim formulations have been developed independently by Bayer AG and the Centers for Disease Control (CDC). Both methods specify separation on a silica gel column. The Bayer method uses a 5% solution of tetrahydrofuran in hexane as the eluting solvent and quantitates results on the basis of an external standard. The CDC method uses a 5% solution of ethyl acetate in hexane as the eluting solvent and uses 4-fluorophenyl sulfone as an internal standard. The 2 methods were compared by replicate analyses of samples of chlorphoxim technical and water-dispersible powder and emulsifiable concentrate formulations. The precision of both methods was acceptable.     

Landscape sensitivity: an ecological view

This paper briefly explores the concept of landscape sensitivity from an ecological perspective by addressing the questions: what is landscape, what is landscape sensitivity, what are the mechanisms of change, and what can landscape change mean for the species living there? Landscape to an ecologist is the vegetation and associated faunal populations draped over the geomorphology that give it most of its colour and texture. The concept of landscape sensitivity seems little used in ecology, and is taken here to mean instability versus stability. This is then explored, using examples mainly from the uplands of Scotland, but beginning with the fact that the vegetation cover over much of Scotland changed during the period 1946–1988, with for example ca. 50% or more change in vegetation types in about half of Scotland. The commonness and speed of change are stressed, and also the scale dependency of detected change, i.e. changes in particular attributes may go in opposite directions at contrasting spatial scales. Mechanisms of vegetation change, particularly the effects of grazing on vegetation, are discussed. Within the physiognomic gradient from grassland to woodland in the Scottish uplands, there are two broad thresholds of grazing pressure. When these thresholds are crossed, contingency effects can be particularly important in controlling the ensuing successions. Also, when vegetation changes, labile soil properties such as pH can also change, with feedback effects on the species composition of the vegetation. Finally, the implications of landscape change for species in upland Scotland are exemplified by changes in birds and vascular plants.     

Identification of microphases in mixed alpha- and omega-gliadin protein films investigated by atomic force microscopy

Pure and mixed films of alpha- and omega-gliadins were studied by tapping mode atomic force microscopy (AFM). The technique was sensitive to the chemistry of the surface properties of the films, allowing imaging of the mixed gliadin phases at different ratios. In addition to the study of the phases at the micrometer level, higher resolution images allowed visualization of the protein films at the molecular level. These studies may have relevance to the formation of phases in developing protein bodies in grain, where gliadins and glutenins are deposited together. It has been assumed that the protein bodies consist of a random network of proteins; these studies indicate that microphases could be present in protein bodies. The technique provides novel methods for studying mixed biopolymer systems.     

Determination of oxyfluorfen herbicide and oxyfluorfen amine residues in garbanzo beans by liquid chromatography

Oxyfluorfen and oxyfluorfen amine were determined by liquid chromatography (LC) with ultraviolet (UV) and photoconductivity detection (PCD). A simple extraction procedure acceptably recovered both analytes from garbanzo beans over a wide range of fortifications (0.05 to 20 ppm) (83 +/- 4 for oxyfluorfen; 85 +/- 4 for oxyfluorfen amine). Percent recoveries decreased slightly as the fortification level decreased. Both analytes could be determined simultaneously at a concentration greater than 0.2 ppm in garbanzo beans. Detection limits were 3 ng for oxyfluorfen and 100 ng for oxyfluorfen amine using LC/UV, and 12 ng for both oxyfluorfen and oxyfluorfen amine with LC/PCD. Different knitted reaction coils and photoreactors were evaluated. Photoproduct yields and identification were determined by ion chromatography. The LC/PCD method measures oxyfluorfen and oxyfluorfen amine separately and has a shorter analysis time, while the standard method using gas chromatography measures total residues and is more sensitive.