Carbohydrate metabolism, comparative

As with urine, saliva (spumm) is easy to collect. The levels of protein and lipids in saliva or spumm are low (compared to blood samples). These matrices are viscous, which is why extraction efficiency of xenobioties amoimts to only 5 to 9%. By acidifying the samples, extraction efficiencies are improved as the samples are clarified, and proteinaceous material and cellular debris are precipitated and removed. Some xenobioties and their metabohtes are expressed in hair. Hair is an ideal matrix for extraction of analytes to nonpolar phases, especially when the parent xenobioties are extensively metabolized and often nondetectable in other tissues (parent molecules of xenobioties are usually less polar than metabolites). Hair is a popular target for forensic purposes and to monitor drug compliance and abuse. Human milk may be an indicator of exposure of a newborn to compounds to which the mother has been previously exposed. The main components of human milk are water (88%), proteins (3%), lipids (3%), and carbohydrates in the form of lactose (6%). At present, increasing attention is devoted to the determination of xenobioties in breath. This matrix, however, contains only volatile substances, whose analysis is not related to PLC applications. 

Saz, H.J. and Lescure, O.L. (1966) Interrelationships between the carbohydrate and lipid metabolism of Ascaris lumbricoides egg and adult stages. Comparative Biochemistry and Physiology 18, 845-857. 

Figure 3.12 Metabolic profiling by capillary electrophoresis, (a) Comparative carbohydrate profiles of M. truncatula tissue obtained using 4-aminobenzonitrile derivatization, capillary electrophoresis with a 150 mM borate buffer, pH = 9, and on-column UV detection at 214 nm. (b) Anion profile from M. truncatula using capillary electrophoresis and indirect UV detection. The separation buffer was 5 mM K2C1O4, 1% Waters OFM-Anion BT, pH 8.0.

P is crucial for several aspects of plant metabolism, especially the energy and sugar metabolism, and several enzymatic reactions, including photosynthesis. Plants have therefore developed mechanisms for the uptake and efficient use of P. Maize plants recycled N quicker from old to young tissue when P is deficient, leading to earlier leaf senescence (Usuda 1995). P-deficient plants invest more resources into root development and therefore have an increased root-to-shoot biomass ratio compared to well-nourished plants. Furthermore, they accumulate more carbohydrates in leaves and allocate more carbon to the roots (Hermans et al. 2006). 

The calorific capacity of amino acids is comparable to that of carbohydrates so despite their prime importance in maintaining structural integrity of cells as proteins, amino acids may be used as fuels especially during times when carbohydrate metabolism is compromised, for example, starvation or prolonged vigorous exercise. Muscle and liver are particularly important in the metabolism of amino acids as both have transaminase enzymes (see Figures 6.2 and 6.3 and Section 6.4.2) which convert the carbon skeletons of several different amino acids into intermediates of glycolysis (e.g. pyruvate) or the TCA cycle (e.g. oxaloacetate). Not all amino acids are catabolized to the same extent... 

The study of genetic defects in the oxidation of fat fuels is a relatively new field compared with the study of such defects in carbohydrate and amino acid metabolism. The first genetic defect was reported in 1970 and the first enzyme deficiency in 1973. The probable reasons for the late discovery of these defects are of some interest ... 

Fatty acids stored in adipose tissue, in the form of neutral TAG, serve as the body s major fuel storage reserve. TAGs provide concentrated stores of metabolic energy because they are highly reduced and largely anhydrous. The yield from complete oxidation of fatty acids to CO2 and H2O is nine kcal/g of fat (as compared to four kcal/g of protein or carbohydrate, see Figure 27.5, p. 357). 

Amitrole had a drastic effect on the fixation of 14C02 by illuminated chloroplasts of Chlorella pyrenaidom, lowering the incorporation into sucrose by 95% at a concentration of 500 mg. per liter it did pot affect phosphorylated compounds.145 Carbohydrates hydrolyzable by acids were higher (51%) in treated, chlorotic corn leaves than in controls (32%), and this result was interpreted as due to increased metabolism of proteins and fats. The respiratory quotient of 0.8 to 0.88, compared to controls near 1.0, supported this interpretation.145... 

Ethanoic acid is activated for biosynthesis by combination with the thiol, coenzyme A (CoASH, Figure 18-7) to give the thioester, ethanoyl (acetyl) coenzyme A (CH3COSC0A). You may recall that the metabolic degradation of fats also involves this coenzyme (Section 18-8F) and it is tempting to assume that fatty acid biosynthesis is simply the reverse of fatty acid metabolism to CH3COSCoA. However, this is not quite the case. In fact, it is a general observation in biochemistry that primary metabolites are synthesized by different routes from those by which they are metabolized (for example, compare the pathways of carbon in photosynthesis and metabolism of carbohydrates, Sections 20-9,10). 

Morphological changes were also observed on callus of Pinus laricio cultured for 4 weeks with HS extracted from forest soil under Abies alba and Fagus sylvatica plantation or the hormones 2,4D, IAA, and 6BAP (Muscolo et al., 2005).The results showed that both high- and low-molecular-weight humic fractions inhibited callus growth compared to the control and affected the enzymes involved in carbohydrate metabolism. 

Black, E.C., Robertson, A.C. and Parker, R.R (1961). Some aspects of carbohydrate metabolism in fish. In Comparative Physiology of Carbohydrate Metabolism in Heterothermic Animals . (A.W. Martin, ed.), pp.89-124. University of Washington Press, Seattle. 

Lewander, K., Dave, G., Johansson, M.-L., Larsson, A. and Lidman, U. (1974). Metabolic and haematological studies on the yellow and silver phases of the European eel, Anguilla anguilla. -1. Carbohydrate, lipid, protein and inorganic ion metabolism. Comparative Biochemistry and Physiology 47B, 571-581. 

Soengas, J.L., Otero, J. Fuentes, J., Andrds, M.D. and Aldegunde, M. (1991). Preliminary studies on carbohydrate metabolism changes in domesticated rainbow trout (Oncorhynchus mykiss) transferred to diluted sea water (12 p.p.t). Comparative Biochemistry and Physiology 98B, 53-57. 

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