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71.
Nine monoclonal antibodies which react with the beta subunit of the yeast mitochondrial H+-ATPase and three which react with a 25 kDa subunit of the enzyme complex (P25) have been characterized. Competitive binding studies indicated the presence of at least four antigenic regions on the beta subunit of the enzyme complex. One antigenic region of the beta subunit is recognized by two monoclonal antibodies RH 57.1 and RH 45.5 which inhibit the ATPase activity to different degrees. Antibody RH 48.6 appears to bind to a second region on the beta subunit and has no effect on the ATPase activity. A third region of the beta subunit is recognized by antibodies RH 51.4 and RH 72.1. RH 51.4 has no effect on the ATPase activity, whereas RH 72.1 stimulates ATPase activity. Antibody RH 32.4 which has no effect on the ATPase activity appears to bind to the fourth epitope of the beta subunit. All three monoclonal anti-P25 antibodies, RH 66.3, RH 41.2 and RH 37.0, apparently bind to the same antigenic region on this subunit. Two of the monoclonal anti-beta antibodies RH 48.6 and RH 51.4 were found to be very effective in immunoprecipitating the whole H+-ATPase complex in a solid phase system. However, the other monoclonal antibodies (and also a polyclonal antiserum) appear to induce the dissociation of one or more of the H+-ATPase subunits by their binding to the epitopes on the beta or the P25 subunits. 相似文献
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The climbing habit has evolved independently in many plant taxa, offering vines the ability to compete with non-climbing vegetation
for resources such as light, nutrients, and water. This review examines the structural and functional characteristics that
allow climbing plants to (1) achieve widespread dispersal, (2) transport large amounts of water throughout vessels, (3) maintain
high photosynthesis levels through a large leaf area to biomass ratio, (4) achieve rapid vertical and horizontal expansion
by fast growth rates and various climbing mechanisms and (5) survive and recover from disturbances. Due to the competitive
effects of vines on trees, management of vine growth is used to preserve tropical timber plantations, combat invasive weeds,
and promote rainforest recovery. In order to sustainably manage the vines into the future, it is necessary to understand the
mechanisms by which they can alter tropical forest succession and the impacts of various management techniques. 相似文献
74.
Ken Walder Carolyn R. Dascaliuc Paul A. Lewandowski Andrew J. Sanigorski Paul Zimmet Greg R. Collier 《Obesity (Silver Spring, Md.)》1997,5(3):193-200
Food intake was restricted to 75% of ad libitum levels in 37 male Psammomys obesus (Israeli Sand Rats) from the ages of 4 (weaning) to 10 weeks. Energy restriction reduced the mean body weight at 10 weeks by 29% compared with 44 ad libitum fed controls. Hyperglycemia was prevented completely in the food-restricted group, and mean blood glucose concentrations were significantly reduced (3.8 ± 0.2 vs. 5.5 ± 0.4 μmol/L; p<0.05) compared with control animals. Plasma insulin concentrations were also decreased significantly compared with ad libitum fed controls (105 ± 13 vs. 241 ± 29 mU/L;p<0.05). Although energy restriction prevented hyperglycemia from developing in 10-week-old P. obesus, 19% of the food restricted animals still developed hyperinsu-linemia. We concluded that hyperphagia between the ages of 4 to 10 weeks may be essential for the development of noninsulin-dependent diabetes mellitus in P. obesus, but that hyperinsulinemia may still occur in the absence of hyperphagia and hyperglycemia, suggesting a significant genetic influence on the development of hyperinsulinemia in this animal model. 相似文献
75.
Effects of Δ8- and Δ9-tetrahydrocannabinol (Δ8- and Δ9-THC) on three experimentally induced seizure models, i.e., audiogenic seizure (AS) test, maximal electroshock seizure (MES) test and pentylenetetrazol (PTZ)-induced seizure test were determined in the audiogenic rat. Both tetrahydrocannabinols possess a dose-related anticonvulsant effect against AS, MES and PTZ-induced maximal seizure. Although anticonvulsant potencies do not significantly differ, Δ8THC is three times more neurotoxic than Δ9THC. In addition, both THC's are without effect on minimal seizure and lethality induced by PTZ. Furthermore, the low protective indexes (TD50/ED50) determined in this study suggest that Δ8 and Δ9 THC may have poor therapeutic potentials as antiepileptic drugs. 相似文献
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