Disruptive selection

In addition to reproductive effects, fish exposed to endocrine disrupters may have a decreased response to stress or decreased growth and metabolism which can affect their ability to survive, or to defend themselves against predators. All of these factors can affect the ability of the species to survive and to reproduce itself in sufficient numbers to maintain the stocks on which our commercial and sport fisheries are based. Not all fish species will be equally susceptible to the effects of endocrine disrupters. Selective sensitivity to such effects, especially those affecting reproduction, may well lead to major changes in the flora and fauna of some of our major aquatic ecosystems as the balance between fish, mammals, invertebrates and plants, and between predators and prey, is destabilised... 

Galen, C., Zimmer, K. A. and Newport, M. E. (1987). Pollination in floral scent morphs of Polemonium viscosum a mechanism for disruptive selection on flower size. 

Increased electronegativity causes the disruption Selective precipita-of the noncovalent forces. tion of the proteins... 

Both methods are transitory and the barrier closes within 10-20 minutes of the initiation of BBB disruption. Hyperosmolar BBB disruption selectively opens the BBB in normal brain, as compared to the barrier in brain tumors. Conversely, biochemical BBB disruption selectively increases barrier permeability in brain tumors, with minimal disruption of barrier permeability in normal brain. 

Resistance towards azoles has been observed in the field particularly in the case of powdery mildews. Field monitoring has shown that the development of resistance proceeds by directional rather than disruptive selection. 

Plasticization Gas solubility in the membrane is one of the factors governing its permeation, but the other factor, diffusivity, is not always independent of solubility. If the solubility of a gas in a polymer is too high, plasticization and swelhng result, and the critical structure that controls diffusion selectivity is disrupted. These effects are particularly troublesome with condensable gases, and are most often noticed when the partial pressure of CO9 or H9S is high. H9 and He do not show this effect This problem is well known, but its manifestation is not always immediate. 

The OECD has been very active in the development of a concensus on tests for endocrine disruption in fish, including selection of enhancements to guidelines... 

Atovaquone, a hydroxynaphthoquinone, selectively inhibits the respiratory chain of protozoan mitochondria at the cytochrome bcl complex (complex III) by mimicking the natural substrate, ubiquinone. Inhibition of cytochrome bcl disrupts the mitochondrial electron transfer chain and leads to a breakdown of the mitochondrial membrane potential. Atovaquone is effective against all parasite stages in humans, including the liver stages. 

Biopsy findings show disseminated muscle fiber atrophy which is confined to type 2 fibers, in many instances with type 2B (glycolytic) fibers most affected (Figure 23). Muscle necrosis is not seen, though at ultrastructural level focal myofibrillar disruption and myofilament loss may be evident. The muscle atrophy seems to be due to decreased protein synthesis, and at high doses, to increased catabolism. The reason for the selective effect on phasic, glycolytic fibers is not clear since, although steroids interfere with carbohydrate metabolism and oxidative capacity, there seems to be no overall effect on ATP levels. Nevertheless it has been... 

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