Species variation

Walker, C.H. (1980). Species variations in some hepatic microsomal enzymes that metabolise xenobiotics. Progress in Drug Metabolism 5, 118-164. 

Chromatin remodeling, transcription factor modification by various enzyme activities, and the communication between the nuclear receptors and the basal transcription apparatus are accomplished by protein-protein interactions with one or more of a class of coregulator molecules. The number of these coregulator molecules now exceeds 100, not counting species variations and splice variants. The first of these to be described was the CREB-binding protein, CBP. CBP, through an amino terminal domain, binds to phosphorylated serine 137 of CREB and mediates transactivation in response to cAMP. It thus is described as a coactivator. CBP and... 

Huang J.W., Cunningham S.D. Lead phytoextraction Species variation in lead uptake and translocation. NewPhytol 1996 134 75-84. 

A) Check to see if the spectrum is symmetric in line positions and relative intensities. If it is not, then most likely there are two or more radical species. Variation of line widths with / , may, in principle, cause the spectrum to appear unsymmetric, but in such a case line positions would still be at least approximately symmetrically distributed about the center. 

We emphasise that the next chapters refer only to the surface of Earth to which light and the atmosphere have access. This is a common restriction in the discussion of evolution but we shall have to examine also the geological and biochemical zones in (and beneath) the deep sea (in Chapter 11), where it appears that evolution could be taking a somewhat different and as yet less advanced route but based on the same principles. We emphasise that each chapter adds new uses of elements, of energy, of space, and of organisation with species variation as new chemotypes evolved. The thermodynamic characteristics of all cells are given in Table 4.11. 

Mathieson, S. and D.S. McLusky. 1995. Inter-species variation of mercury in skeletal muscle of five fish species from inshore waters of the Firth of Clyde, Scotland. Mar. Pollut. Bull. 30 283-286. 

For those interested in the discovery of drug candidates to attenuate SSAO/ VAP-1 activity there are two properties that need to be considered. First, as mentioned above, SSAO/VAP-1 exists as a membrane bound protein and a truncated version is found in the plasma [10,11]. Second, there is tremendous species variation which is revealed in a very large range of the second order rate constant V/K, using benzylamine as substrate, [22,23], and that inhibitor potencies vary widely according to the species [24,25]. Furthermore, within a single species specific activity varies from tissue to tissue [26]. 

There is no agreement on the exact magnitude of the ultrafiltrable or high-molecular-mass fraction of Ni(II) in human serum. Moreover, pronounced species variations in the proportions of ultrafiltrable and protein-bound serum nickel have been demonstrated [289],... 

Yang RS, Coulston F, Goldberg L. 1975. Binding of hexachlorobenzene to erythrocytes Species variation. Life Sci 17(4) 545-549. 

Molecular phylogeny is a discipline that studies species differences between DNA or protein sequences. Its basic tenet is that during evolution, the sequences have drifted apart by mutation and selection as well as by random drift and fixation of variants in certain positions. The earlier two species separated the more differences became fixed. Phylogenetic trees are constructed on the basis of mutual differences of protein and/or DNA sequence. Comparison of intraspecies variation with between-species variation may in the future yield information on the neutralist/selectionist alternative. McDonald and Kreitman (1991) devised an interesting test against neutrality that compared the ratio of silent/replacement mutation of a given locus within a species with the same ratio between two related species. Under the neutral theory this should be equal (corrected for sample size), but in fact it is not (see Li, 1997, and Hudson, 1993, for a discussion). 

Unlike premixed flames, which have a very narrow reaction zone, diffusion flames have a wider region over which the composition changes and chemical reactions can take place. Obviously, these changes are principally due to some interdiffusion of reactants and products. Hottel and Hawthorne [5] were the first to make detailed measurements of species distributions in a concentric laminar H2-air diffusion flame. Fig. 6.5 shows the type of results they obtained for a radial distribution at a height corresponding to a cross-section of the overventilated flame depicted in Fig. 6.2. Smyth et al. [2] made very detailed and accurate measurements of temperature and species variation across a Wolfhard-Parker burner in which methane was the fuel. Their results are shown in Figs. 6.6 and 6.7. 

FIGURE 6.5 Species variations through a gaseous fuel-air diffusion flame at a fixed height above a fuel jet tube. 

FIGURE 6.6 Species variations throughout a Wolfhard-Parker methane-air diffusion flame (after Smyth etal. [2]). 

Much of the inter-species variation in pharmacokinetic properties can be explained as a consequence of body size (allometry). Consequently it is possible to scale pharmacokinetic parameters to the organism s individual anatomy, biochemistry and/or physiology in such a manner that differences between species are nuUified. Several excellent reviews on allometric scaling are available in the literature [2-7]. Allometric relationships can be described by an equation of the general form ... 

Comparative Toxicokinetics. Limited data are available regarding comparative toxicokinetics. The acute oral LDjo values in guinea pigs and rabbits for kerosene has been reported to be 16,320 mg/kg and 22,720 mg/kg, respectively (Deichmann et al. 1944). These data suggest that there may be species differences in the oral toxicity of kerosene however, more data would be needed to thoroughly examine species variation in toxicokinetics. This information would be useful to identify similar target organs and to adequately assess which animals can serve as the best models for humans, as well as to define mechanisms of action. 

Differences among species in distribution patterns of histological changes may be caused by species variations in the distribution in the nasal epithelium of chemical-metabolizing enzymes. For example, in rats exposed to methyl methacrylate, nasal lesions were shown to be caused by the carboxylesterase mediated metabolism of methyl methacrylate to methacrylic acid, an irritant and corrosive metabohte. The distribution of these enzymes in the nasal tissues of man, rat, and hamster indicated a lower rate of metabolism in man compared to rat and hamster, suggesting a lower sensitivity to methacrylate in humans (Mainwaring et al. 2001). 

Reduced testes weights and histologic evidence of testicular injury were found in rats and guinea pigs but not hamsters or mice fed 2g/l /day DBP for 10 days, indicating a species-specific response. The basis of this species variation may be related to species differences in the ability to conjugate monobutyl phthalate, the primary metabolite of DBP, with glucuronic acid. ... 

In studies of species variation different conclusions may be reached when the transferases are incubated with or without activating ion. Until the significance of the cation-dependent and -independent activities is better understood, parallel assays of both may be preferable. No firm recommendations can be made. 

There seems to be a desire among the workshop participants to develop a series of standard distributions, or distribution parameters, for exposure and effects variables that are generally used in risk assessments. In the case of toxicity data, for example, investigations leading to the quantification of a generic variance for between-species variation from pooled data for many pesticides may be useful (Luttik and Aldenberg 1997). 

Nau HJ (2001) Teratogenicity of isotretinoin revisited species variation and the role of all-trans-retinoic acid. J Am Acad Dermatol 45(5) S183-S187... 

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