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951.
Michael S. Rose Helen C. Crabtree Kenneth Fletcher Ian Wyatt 《The Biochemical journal》1974,138(3):437-443
1. Administration of diquat (NN'-ethylene-2,2'-bipyridilium) or paraquat (NN'-dimethyl-4,4'-bipyridilium) prevents the normal depletion of liver glycogen in starved rats. 2. There is an increase in blood glucose, which returns to normal values after approx. 7h. 3. After administration of diquat or paraquat, plasma corticosteroids increase to very high concentrations and remain high for at least 24h, but plasma ACTH (adrenocorticotrophin) is only increased for 4h. 4. Adrenal cyclic AMP is considerably increased after administration of diquat and remains significantly higher than control values for at least 24h. 5. It is suggested that diquat and paraquat increase the response of the adrenal cortex to ACTH. 相似文献
952.
Robert Wyatt 《American journal of botany》1982,69(4):585-594
The adaptive significance of different types of inflorescences in flowering plants has been largely ignored. The few published studies investigating adaptive aspects of floral displays suggest that numbers of flowers and their arrangement in space and time determine levels of pollination and fruit-set in natural populations. The frequently conflicting demands placed on inflorescence architecture have led to an evolutionary compromise that maximizes the genetic contribution of an individual plant to the next generation. These conflicting demands include pollinator attraction vs. ovary competition, fruit dispersal vs. fruit predation, and reproductive vs. vegetative resource allocation. In most cases, the inflorescence size most successful in fruit production is also the most frequent in natural populations. In addition to quantity of offspring, inflorescence architecture affects, and in turn is affected by, the quality of offspring that result from selfing vs. outcrossing. 相似文献
953.
Richard A. Searcy Lynne M. Villers Richard D. Reams John E. Wyatt III Jon Pilarski 《Zoo biology》2009,28(4):343-349
The Jamaican iguana (Cyclura collei) was considered to be extinct until its rediscovery in 1990 in the Hellshire Hills region of Jamaica. Between 1994 and 1996, several wild caught juveniles were placed in six North American zoological institutions including the Indianapolis Zoo. The intent was to establish a self-sustaining captive population outside of Jamaica in order to serve as an ancillary population should the wild numbers decline. Several environmental parameters such as temperature, humidity, photoperiod and diet were manipulated to encourage reproduction in captivity. In 2006, two clutches of eggs were deposited by two separate females for a total of 35 eggs. Twenty-six eggs were fertile and 22 hatched after a 76–83-day incubation at 30.3–30.8°C (86.5–86.7°F). The average weight of the neonates was 26.4 g and the average total length was 21.7 cm. This successful reproduction of C. collei constitutes the first North American hatching for this species. Environmental parameters, incubation techniques and neonate morphometry can serve as a baseline for further propagation of the species. This represents a positive milestone for the continuing conservation of this critically endangered species. Zoo Biol 28:343–349, 2009. © 2009 Wiley-Liss, Inc. 相似文献
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Molecular modeling of hapten structure and relevance to broad specificity immunoassay of sulfonamide antibiotics. 总被引:2,自引:0,他引:2
Molecular modeling of hapten structure was used to predict and influence, through appropriate synthetic work, the outcome of an immunization program. Examination of the structures of sulfonamide antibiotics led to the development of a hypothesis and the consequent synthesis of a sulfacetamide-protein immunogen aimed at the generation of broad specificity anti-sulfonamide antibodies. The antisera generated, alongside anti-sulfachlorpyradizine antisera generated at the same time, were characterized for cross-reactions against a range of sulfonamide drugs, and were found to exhibit good but not the desired broad specificity. Discussion is presented as to the reasons for the failure of the hypothesis. Further hypotheses are developed and speculation is made as to the future of molecular modeling in immunochemical research. 相似文献
959.
Hybridization of a cloned DNA probe to blots of restriction digests of Locusta migratoria genomic DNA showed that a vitellogenin gene is present at one copy per haploid genome in females, and at only one-half that number in males. The genomic region encompassing the 3′-coding end of the gene is polymorphic, as revealed by blots of DNA from individual locusts. DNA from some female locusts yielded two variants in this region, whereas a series of male locusts showed one variant or the other, but never both. The results demonstrate that the vitellogenin gene, which is normally expressed only in females, is X-linked in L. migratoria. 相似文献
960.
Farouk Karoum Stanislaw J. Chrapusta Michael F. Egan Richard Jed Wyatt 《Journal of neurochemistry》1993,61(4):1369-1375
Abstract: Formation of 6-hydroxydopamine (6-OHDA) from dopamine has been hypothesized to mediate neuro-degeneration induced by some psychostimulants. Although the emergence of a 6-OHDA-like substance was reported in the striatum of methamphetamine-treated rats, this substance has not been identified by a direct approach. We used mass fragmentography to search for 6-OHDA in the rat frontal cortex and striatum after the administration of a number of drugs including 3,4-dihy-droxyphenyl-L-alanine, methamphetamine, amphetamine, and cocaine, all of which increase synaptic dopamine. No 6-OHDA was detected after the acute systemic administration of these agents. Intraventricular administration of 6-OHDA (10 μg/rat.) produced measurable concentrations of 6-OHDA that were higher in the striatum than in the frontal cortex. Intraventricular administration of 2,4,5-trihydroxy-phenyl-D,L-alanine (6-OHDOPA; 10 μg/rat) produced similar concentrations of 6-OHDA in both regions. Pargyline, but not carbidopa (α-methyldopahydrazine), enhanced the effect of intraperitoneal 6-OHDOPA administration (80 mg/kg). We conclude that (1) 6-OHDOPA can cross the blood-brain barrier and is converted to 6-OHDA in the brain, (2) 6-OHDA is a substrate for monoamine oxidase(s) and therefore a search for its purported deaminated metabolite is warranted, and (3) acute treatment with the above stimulants either does not lead to the formation of 6-OHDA or produces concentrations below the detection limit of the assay (<34 pg/mg of protein). 相似文献