Isolation from land plants

Isolation and Comparison of Nucleic Acids from Land Plants Nuclear and Organellar Genes... 

The distinction between the isotopic compositions of n-alkanes from land-plants having different metabolic pathways has been used by Bird et al. (1995) to trace the history of changes in the amounts of C3 and C4 plants in the watershed of the Johnstone River, northern Queensland, Australia. Clearing of the original forests for sugarcane production and pastures is recorded in a +3%o shift in the values of n-alkanes isolated from river sediments deposited since the late 18(X) s. A smaller shift of + l%o that occurs in sediments... 

The hetero-l,4-linked xylans (or heteroxylans) constitute a well-characterized group of polysaccharides which form the major components of the hemicellulosic fractions of terrestrial plants (1-4). Softwoods are an exception, where the heteroxylans can be present as a minor component of the total hemicelluloses. They have been isolated from grasses, legumes, ferns, softwoods and hardwoods, and collectively may constitute up to 35% of the total dry weight of higher land plants (4). As such the heteroxylans rank second to cellulose in abundance as naturally occurring organic chemicals in the biosphere. The heteroxylans are closely associated with other... 

The name alkali is derived from the Arabic Al kaljun, meaning the ashes of sea-plants and land-plants. Prior to the French Revolution the carbonates of sodium and potassium were manufactured by lixi-viation of these ashes and, on the isolation of sodium and potassium (pp. 82 and 152), the name was employed to denote the group of which they are typical. 

With discretion, the structural information on features in xylans from other, higher land-plants can be used to assist, as in the past, in the search for similar features in the hemicellulose of plantstuffs under examination—no matter how often they have been previously examined. If new facts suggest new interpretations, earlier studies should be re-examined to determine whether the newer interpretation accords with facts established earlier. It is a misfortune of hemicellulose chemistry that it is rarely possible to disprove a reported fact, as, unless total hemicelluloses30,31 are isolated from plants of the same variety or cultivar grown under very similar conditions to the plants studied earlier, the hemicellulosic material under examination may not contain molecules having detectable amounts of the structural features noted earlier. 

Hemicelluloses are non-cellulosic low molecular weight polysaccharides that are found together with cellulose in plant tissues 1311. In the cell walls of land plants, xylan is the most common hemicellulosic polysaccharide, representing more than 30% of the dry weight 1321. Most xylans are heteropolysaccharides which are composed of 1,4-linked (3-D-xylopyranosyl residues 133, 134, 135). This backbone chain is substituted with acetyl, arabinosyl, and glucuronosyl residues 133. Homoxylans, on the other hand, consist of xylosyl residues exclusively and have been isolated from esparto grass 136, tobacco stalks 137, and guar seed husk 138. ... 

In other, land, plants the following natural products were isolated from ... 

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