Compositional differences among varieties

On the other hand, the prediction by content approach is applicable regardless of the variety of sorting pathways. It may be applied to partial sequences, which are now massively produced day by day. In addition, this approach allows a simple and unified treatment, which is convenient for objective testing (e.g., cross validation). However, there is no guarantee that the amino acid composition of proteins in each localization site is well conserved. Even when a clear tendency is observed for a known set of proteins, it can be an artifact resulting from the deviation of data because the size of known proteins for each site is often insufficient to perform reliable statistical analyses. It is also evident that this approach cannot handle the differences among isoforms with different localization (see Section III,K,3). 

Collectively, valerian extracts show a variety of GABAergic mechanisms. The predominant mechanism has yet to be determined, but an additive or synergistic interaction among the several mechanisms is Dossible. Future research on valerian extracts needs to address any compositional differences Detween aqueous and nonaqueous extracts, and to determine the responsible active constitutents. 

More recently, static headspace GC analysis of eight cultivars of melons detected esters as the major volatile components. Differences among the compositions of the volatiles of the cultivars studied were also reported and are probably due to different efficiencies of biosynthetic pathways of each variety [56]. 

Walnuts contain about 65% lipids, however, considerable differences exist among varieties (range 52-70%, w/w) (1,40). Walnuts also contain 15.8% protein, 13.7% carbohydrate, 4.1% water, and 1.8% ash (w/w) (1). The fatty acid composition of walnut oil is unique compared with other tree nut oils for two reasons walnut oil contains predominantly linoleic acid (49-63%) and a considerable amount of ot-linolenic acid (8-15.5%). Other fatty acids present include oleic acid (13.8-26.1%), palmitic acid (6.7-8.7%), and stearic acid (1.4—2.5%) (Table 5) (40). The tocopherol content of walnut oil varies among different cultivars and extraction procedures and ranges between 268 mg/kg and 436 mg/kg. The predominant tocol isomer is y-tocopherol (>90%), followed by a-tocopherol (6%), and then (3- and 8-tocopherols (41). Nonpolar lipids have been shown to constitute 96.9% of total lipids in walnut oil, whereas polar lipids account for 3.1%. The polar lipid fraction consisted of 73.4% sphingolipids (ceramides and galactosylcera-mides) and 26.6% phospholipids (predominantly phosphatidylethanolamine) (42). Walnut oil contains approximately 1.8g/kg phytosterols (1), primarily p-sitosterol (85%), followed by A-5-avenasterol (7.3%), campesterol (4.6%), and, finally, cholesterol (1.1%) (42). 

Chemical composition may explain, for large part, the differences in product distribution among the different wood varieties. Previous studies report that... 

There are over three hundred recognizable varieties, some of which are only a few inches in height, while others are giants of six feet or more some come to maturity in two months, while others require three or four times as long before their cobs ripen. There is also great variety in the shape, size, and color of the actual grain. Some are white as, for example, the Cuzco maize, others are yellow, red, purple, or even striped, and the varieties differ among themselves in chemical composition. 

In a study of various woods in peat. Stout et al. (42) observed particularly rapid decreases in specific pyrolysis products of hemicelluloses, such as anhydroxyloses, which also were interpreted to indicate that hemicelluloses are degraded faster than celluloses. The same trend has been reported for ancient oak woods (4). However, the composition trends among the neutral sugars obtained by Boutelje and Goransson (37) from different depths within submerged redwood piles indicate that hemicellulose is more stable. Preferential cellulose loss was also reported by liyama et al. (51) for woods from soils and a peat. More comparative analyses of the neutral and acidic sugar compositions of buried woods from a variety of environments will be necessary to resolve the present disparate observations. 

Each of the about 450 lupin species which have been identified differs in both content and composition of QAs. The problem of great difference of QAs content is further complicated as it can fluctuate among the different genetic varieties of the same species. QAs content depends also from environmental conditions, soil characteristics, drought, etc. Moreover, substantial variations are found in the alkaloid patterns of different organs seeds, leaves, pods, roots, flowers. 

Although many chemical analyses of vermiculites have been published, and considerable differences in composition exist among different specimens, no subdivision of the vermiculite group into distinct species has yet been made. A number of variety names for vermiculites from different localities are listed in Dana [1932], but not all of these can be regarded as true species. The iron-free vermiculite described by Weinschenk [1897] and Weiss and Hofmann [1951], however, is generally referred to as batavite. 

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