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81.
It has been suggested that the carbohydrate-rich diet of chicks after hatching is responsible for the emergence of hepatic enzymes involved in lipogenesis; the injection of glucose to newly hatched chicks gives rise to an appreciable elvation on the activities of acetyl coenzyme A carboxylase and fatty acid synthetase. The present study shows that during the first hours after hatching, there is a natural elevation of glycemia which parallels the increase in acetyl coenzyme A carboxylase activity. However, the administration of hormones which alter the blood glucose levels considerably (insulin, tolbutamide, glucagon and hydrocortisone) did not influence the enzyme activity. The administration of thyroxine, estradiol and cyclic AMP, was also without effect. These results do not support the theory that the increased amount of blood glucose is the natural effector of the induction acetyl coenzyme A carboxylase. They also show that different lipogenic enzymes are not regulated via the same 'operon' since thyroxine or glucagon which alter the level of some enzymes on this pathway did not modify that of the acetyl coenzyme A carboxylase. 相似文献
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Large, rapidly evolving intergenic spacers in the mitochondrial DNA of the salamander family Ambystomatidae (Amphibia: Caudata) 总被引:5,自引:2,他引:3
We report the presence, in the mitochondrial DNA (mtDNA) of all of the
sexual species of the salamander family Ambystomatidae, of a shared 240- bp
intergenic spacer between tRNAThr and tRNAPro. We place the intergenic
spacer in context by presenting the sequence of 1,746 bp of mtDNA from
Ambystoma tigrinum tigrinum, describe the nucleotide composition of the
intergenic spacer in all of the species of Ambystomatidae, and compare it
to other coding and noncoding regions of Ambystoma and several other
vertebrate mtDNAs. The nucleotide substitution rate of the intergenic
spacer is approximately three times faster than the substitution rate of
the control region, as shown by comparisons among six Ambystoma
macrodactylum sequences and eight members of the Ambystoma tigrinum
complex. We also found additional inserts within the intergenic spacers of
five species that varied from 87-444 bp in length. The presence of the
intergenic spacer in all sexual species of Ambystomatidae suggests that it
arose at least 20 MYA and has been a stable component of the ambystomatid
mtDNA ever since. As such, it represents one of the few examples of a large
and persistent intergenic spacer in the mtDNA of any vertebrate clade.
相似文献
87.
大熊猫DNA序列变异及其遗传多样性研究 总被引:3,自引:0,他引:3
张亚平 Oliver A Ryder 范志勇 张和明 何廷美 何光昕 张安居 费立松 钟顺隆 陈红 张成林 杨明海 朱飞兵 彭真信 普天春 陈玉村 姚敏达 郭伟 《中国科学C辑》1997,27(2):139
测定了来自马边、美姑、越西、宝兴、平武、青川、南坪和白水江等地40只大熊猫336~444bp的线粒体tRNA基因和D环区序列.在21个创立者中共检出9种线粒体DNA单倍型.发现大熊猫的遗传分化程度很低,地理群体间无显著的遗传隔离.大熊猫现生群体可能源于晚更新世,并受瓶颈效应的影响.在此之后,其遗传多样性得到了一定程度的恢复. 相似文献
88.
E C Howell S J Armstrong G C Barker G H Jones G J King C D Ryder M J Kearsey 《Génome》2005,48(6):1093-1103
The close relationship between Brassica oleracea and Arabidopsis thaliana has been used to explore the genetic and physical collinearity of the two species, focusing on an inverted segmental chromosome duplication within linkage group O6 of B. oleracea. Genetic evidence suggests that these segments share a common origin with a region of Arabidopsis chromosome 1. Brassica oleracea and Arabidopsis bacterial artificial chromosome probes have been used for fluorescence in situ hybridization analysis of B. oleracea pachytene chromosomes to further characterize the inverted duplication. This has been highly effective in increasing the local resolution of the cytogenetic map. We have shown that the physical order of corresponding genetic markers is highly conserved between the duplicated regions in B. oleracea and the physical lengths of the regions at pachytene are similar, while the genetic distances are considerably different. The physical marker order is also well conserved between Arabidopsis and B. oleracea, with only one short inversion identified. Furthermore, the relative physical distances between the markers in one segment of B. oleracea and Arabidopsis have stayed approximately the same. The efficacy of using fluorescence in situ hybridization, together with other forms of physical and genetic mapping, for elucidating such issues relating to synteny is discussed. 相似文献
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Raffael Nachbagauer Matthew S. Miller Rong Hai Alex B. Ryder John K. Rose Peter Palese Adolfo García-Sastre Florian Krammer Randy A. Albrecht 《Journal of virology》2016,90(6):3268-3273
We assessed whether influenza virus hemagglutinin stalk-based immunity protects ferrets against aerosol-transmitted H1N1 influenza virus infection. Immunization of ferrets by a universal influenza virus vaccine strategy based on viral vectors expressing chimeric hemagglutinin constructs induced stalk-specific antibody responses. Stalk-immunized ferrets were cohoused with H1N1-infected ferrets under conditions that permitted virus transmission. Hemagglutinin stalk-immunized ferrets had lower viral titers and delayed or no virus replication at all following natural exposure to influenza virus. 相似文献