Respiration storage tissues

The major types of adipose tissue are (1) white adipose tissue, which manufactures, stores, and releases lipid and (2) brown adipose tissue, which dissipates energy via uncoupled mitochondrial respiration. Obesity research includes evaluation of the activity of adrenergic receptors and their effect on adipose tissue with respect to energy storage and expenditure or thermogenesis. 

Almost all physiological processes in plants take place in the presence of water. Essential anabolic reactions (photosynthesis, assimilation, and protein synthesis), and catabolic ones (respiration and hydrolysis) occur in an aqueous cellular environment. Essential elements absorbed by plant roots, and the foods and other metabolites manufactured by the leaves and other tissues, move in aqueous solution from the regions of absorption or manufacture to other parts of the plant where additional anabolic reactions and ultimate food storage take place. Water is the major constituent of protoplasm, and is particularly abundant in young and growing tissues. 

In CA/MA storage the 02 and C02 levels are adjusted to inhibit certain degradative reactions, related to respiration, senescence, and tissue softening. The optimal levels of 02 and C02 must be established for each commodity, and this has been done for many fresh fruits and vegetables (2Z) ... 

The tolerance of any plant tissue at low O2 tension is smaller as the storage temperature increases, since the requirements for aerobic respiration of the tissue increases with increasing temperature. Depending on the product damage associated with CO2 can both increase and decrease with rise in temperature. CO2 production increases with temperature, but its solubility decreases. Thus, the CO2 concentration in the tissue may decrease or increase with increasing temperature. In addition, the physiological effect of CO2 could be temperature dependent. 

Let us look first at those seeds in which the cotyledons are the storage organs. A number of researchers have used pea seeds (a hypogeal germinator) for their experiments. Unfortunately, variable, sometimes contradictory results have been found, possibly because different varieties have been employed or, more likely, because the experimental conditions were not standardized. Respiration, differentiation of mitochondria, and other sub-cellular changes are all impaired in detached pea cotyledons [10, 112]. The cotyledons therefore seem to require a factor from the axis for the development and maintenance of respiratory metabolism—this can be supplied even by a small piece of attached axial tissue [112, 119]. As far as protein and starch mobilization in peas are concerned it is unclear if the presence of the axis is necessary. In some cases protein and starch breakdown proceed equally well in detached and attached cotyledons [10] but in others both the development of proteinase activity and... 

Both the permeability of the packaging rrtaterial arrd the respiration of the corrrmod-ity vary with the storage temperatore at differerrt rates. If the two do rrot rrratch at the specific storage conditions, the desired levels of O and CO will not be attairred arrd the deterioration may not be under control. Avery low O level induces fermentation and accumulation of ethanol and acetaldehyde. These resirlt in development of ofif-flavors and/ or tissue damage. The lower limits vary from 0.15% to 5% for different commodities... 

In recent years a number of in vitro experiments have been reported on a variety of plant materials—segments of oat coleoptiles, segments of barley root, cut-up spinach leaves, discs of rhubarb leaves, slices of potato tubers —which demonstrate the utilization of di-and tricarboxylic acids by respiring cells and an increased rate of oxidation on addition of these substances they demonstrate further that malonate inhibits plant respiration. The stimulating effect of the substrates is often absent in fresh material, which is saturated with oxidizable substrates, but it is marked after storage, which depletes the tissue of substrates. The malonate inhibition is usually found only when the medium is acid (pH 5 or below) and when the concentration of malonate is relatively high (0.01 M and above). To obtain the same effects as in animal tissues ten- to a hundredfold concentrations of malonate are required. 

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