Physiological and biochemical

Species Tested. In addition to the variation in susceptibiUty to chemically induced toxicity among members within a given population, there may be marked differences between species with respect to the relative potency of a given material to produce toxic injury. These species differences may reflect variations in physiological and biochemical systems, differences in distribution and metaboHsm, and differences in uptake and excretory capacity. 

The nonvisual or subtle effects of air pollutants involve reduced plant growth and alteration of physiological and biochemical processes, as well as changes in the reproductive cycle. Reduction in crop yield can occur without the presence of visible symptoms. This type of injury is often related to low-level, long-term chronic exposure to air pollution. Studies have shown that field plantings exposed to filtered and unfiltered ambient air have produced different yields when no visible symptoms were present (5). Reduction in total biomass can lead to economic loss for forage crops or hay. 

For future research in this field, in addition to physiological and biochemical approaches, genetic analysis will be essential in the establishment of causal relationships between the induction of a stress protein and the establishment of tolerance to the stress condition. In most cases it is not difficult to detect the induction of new proteins during stress. However, the induction of new proteins does not necessarily establish stress tolerance it may well be the consequence of damage caused by stress conditions. Thus, genetic mutants will be necessary to test the physiological role of a stress protein. 

Toxicity is the outcome of interaction between a chemical and a living organism. The toxicity of any chemical depends on its own properties and on the operation of certain physiological and biochemical processes within the animal or plant that is exposed to it. These processes are the subject of the present chapter. They can operate in different ways and at different rates in different species—the main reasons for the selective toxicity of chemicals between species. On the same grounds, chemicals show selective toxicity (henceforward simply selectivity ) between groups of organisms (e.g., animals versus plants and invertebrates versus vertebrates) and also between sexes, strains, and age groups of the same species. 

Agoram B, Woltosz WS and Bolger MB. Predicting the impact of physiological and biochemical processes on oral drug bioavailability. Adv Drug Deliv Rev 2001 50 Suppl l S41-67. 

Nishikawa, Y., Minenaka, Y, and Ichimura, M., Physiological and biochemical effects of carotenoid (P-carotene and astaxanthin) on rat, Koshien Daigaku Kiyo, 25, 19, 1997 [in Japanese]. 

Although many physiological and biochemical processes In plants are affected by various allelochemicals, In most Instances the details of the mechanism of action of a particular allelochemical have not been elucidated. Because soil mediates the transfer of most allelochemicals (except perhaps volatile compounds) from a donor to a receiver, plant roots are often the first tissues to contact an allelochemical. Thus, It Is not surprising that root growth and development are Inhibited In many Instances of allelopathy (1.-3) One of the primary physiological functions of plant roots Is the absorption of mineral nutrients. Therefore, It Is logical that the Influence of allelopathic Interactions on mineral absorption by plant roots has been Investigated. 

Although the definition of allelopathy Includes stimulation as well as Inhibition of growth by allelochemicals (1., 4), allelochemicals that definitively affect mineral absorption by plant roots have been found to primarily Inhibit, rather than stimulate, the process. The first part of this review presents evidence that alteration of mineral absorption Is a physiological mechanism of allelopathy. Possible physiological and biochemical bases for the Inhibition of mineral absorption by allelochemicals are then discussed. 

Although several allelochemicals (primarily phenolic acids and flavonoids) have been shown to inhibit mineral absorption, only the phenolic acids have been studied at the physiological and biochemical levels to attempt to determine if mineral transport across cellular membranes can be affected directly rather than indirectly. Similar and even more definitive experiments need to be conducted with other allelochemicals that are suspected of inhibiting mineral absorption. Membrane vesicles isolated from plant cells are now being used to elucidate the mechanism of mineral transport across the plasma membrane and tonoplast (67, 68). Such vesicle systems actively transport mineral ions and thus can serve as simplified systems to directly test the ability of allelochemicals to inhibit mineral absorption by plant cells. 

The human body can be considered to be made up of a series of anatomically discrete compartments connected to each other through the circulatory system and by physiological and biochemical links. When... 

Physiological and biochemical changes in the human body are observed when MPC rates in the air are exceeded by a factor of 3-4,... 

Torrans EL, Clemens HP. 1982. Physiological and biochemical effects of acute exposure of fish to hydrogen sulfide. Comp Biochem Physiol C 71 183-190. 

Illes P (1989). Modulation of transmitter and hormone release by multiple neuronal opioid receptors. Review of Physiological and Biochemical Pharmacology, 112, 139-233. 

Application of ultra-high-throughput in silico estimation of biopharmaceutical properties to the generation of rule-based computational alerts has the potential to improve compound selection to those drug candidates that are likely to prove less troublesome in their development. The extension of purely in silico methods to the realm of mechanistic simulation further enhances our ability to predict the impact of physiological and biochemical process on drug absorption and bioavailability. 

In allelopathy studies, the allelochemicals first influence the physiological and biochemical processes in cells. Till now there is no book of methods to study allelopathic interactions in the cells. The activity of cells influence various important physiological processes like seed germination, plant growth and development, photosynthesis and respiration, senescence and abscission are included in this volume. To understand the basic mechanisms of various physiological processes, being affected by allelochemicals at the cellular level enzyme activity and metabolite studies are essential. 

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