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31.
32.
DNA sequence organization of the beta-globin complex in the BALB/c mouse 总被引:41,自引:0,他引:41
C L Jahn C A Hutchison S J Phillips S Weaver N L Haigwood C F Voliva M H Edgell 《Cell》1980,21(1):159-168
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J A Lautenberger M H Edgell C A Hutchison G N Godson 《Journal of molecular biology》1979,131(4):871-875
Bacteriophage G4 possesses a single EcoB site located in the overlap between restriction fragments HinfI-12 and HaeIII-6. The sequence 5′-T-G-A … 8N … T-G-C-T occurs once in this segment and nowhere else in the DNA sequence of G4. Four independent G4 mutants that were not restricted by Escherichia coli B possessed the sequence 5′-T-G-A … 8N … T-G-C-C. The common sequence shared by the previously mapped EcoB sites on φXsB1, simian virus 40, f1, and fd DNAs is 5′-T-G-A … 8N … T-G-C-T … 9N … T. However, the sequence in the region of the G4 EcoB site contains an A instead of the final T conserved in these other examples. When the G4 EcoB site is aligned with the other EcoB sites, there are no conserved residues within 50 bases of the common sequence, 5′-T-G-A … 8N … T-G-C-T, except for those seven residues. The analysis of the EcoB site on G4 provides further evidence that only those seven bases are recognized by the E. coli B restriction enzyme. 相似文献
34.
Dehydrogenases of glycolysis, Kreb's cycle, and pentose-phosphate shunt were detected in cystozoites of Toxoplasma gondii strain SS-119 with various degrees of activity. A mixed oxidative metabolism may be postulated on this stage of the toxoplasma life cycle. Besides, the activity of cytochrome oxidase was detected in cystozoites; the addition of cytochrome c to the incubation medium significantly intensified the reaction intensity. Of interest seems the observation of a layer of higher enzymatic activity in the host brain tissue in the immediate neighbourhood with the cyst body. This may be regarded as the host cells' (or tissue') response to the presence of the parasite's alien body. 相似文献
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The hormonal control of ultrasonic vocal behavior in the male Mongolian gerbil was examined by comparing the behavioral effects of androgen with those of estrogen administered to the preoptic-anterior hypothalamic area (POA-AH) in castrates. By measuring radioactivity released from solid "floating" POA-AH microimplants (mean diameter, 141 microns) of testosterone (3H-T, mean weight, 880 ng) in Experiment 1, we found that the steroid had a concentration gradient which fell rapidly from the edge of the microimplant, suggesting restricted diffusion. Using floating microimplants in Experiment 2, we studied the effects of testosterone propionate (TP, 650 ng), estradiol-17 beta benzoate (EB, 439 ng), or cholesterol (C, 478 ng) on rates of a frequency modulated ultrasonic vocalization emitted during sexual interactions. The effects on the upsweep call were compared with those on sexual mounting. The upsweep rate remained significantly below precastration levels in C implanted males. EB reinstated upsweep calling within 5 days, 3 days earlier than TP microimplants. Mounting in EB implanted males was maintained at precastration levels, whereas TP implantation restored mounting to precastration levels only after 5 days. EB was effective in inducing ultrasonic vocalizations when placed in, or near, the sexually dimorphic area (SDA) in the medial preoptic area (POM). Our results indicate that brain mechanisms underlying both ultrasonic vocalizations and mounting are directly sensitive to estradiol (E2) in the male gerbil. We conclude that E2 affects mechanisms in the SDA associated with ultrasonic calling and suggest that T is likely to act via aromatization products in the brain. 相似文献
37.
After dissociation of cytosolic heteromeric glucocorticoid receptor complexes by steroid, salt, and other methods, only 35-60% of the dissociated receptors can bind to DNA-cellulose. The DNA-binding and non-DNA-binding forms of the dissociated receptors have the same Mr and are phosphorylated to the same extent (Tienrungroj, W., Sanchez, E. R., Housley, P. R., Harrison, R. W., and Pratt, W. B. (1987) J. Biol. Chem. 262, 17347-17349). The basis for the different DNA-binding activities is unknown, but the DNA-binding fraction of the receptor has a more basic pI than the non-DNA-binding fraction (Smith, A. C., Elsasser, M. S., and Harmon, J. M. (1986) J. Biol. Chem. 261, 13285-13292). We have separated the non-DNA-binding state of the receptor from the DNA-binding state and then cleaved it with trypsin and chymotrypsin. We find that the 15-kDa tryptic fragment derived from the non-DNA-binding state of the dissociated receptor is fully competent in binding DNA, whereas the 42-kDa chymotryptic fragment containing both the hormone-binding and DNA-binding domains does not bind DNA. Trypsin cleavage of the molybdate-stabilized untransformed receptor also yields a 15-kDa fragment that is fully competent in binding DNA. Reducing agents do not restore DNA-binding to the non-DNA-binding fraction of the receptor and the hormone-binding domain can be separated from the DNA-binding domain on nonreducing gel electrophoresis. These results argue that the two domains are not linked by disulfide bridges, and they are consistent with the proposal that there are two least energy states of folding after dissociation of hsp90. A significant portion of the receptors is "misfolded" in such a manner that the steroid binding domain is directly preventing DNA-binding activity. 相似文献
38.
The analysis of species-specific subfamilies of both the LINE and SINE mammalian repetitive DNA families suggests that such subfamilies have arisen by amplification of an extremely small group of 'master' genes. In contrast to the master genes, the vast majority of both SINEs and LINEs appear to behave like psudogenes in their inability to undergo extensive amplification. 相似文献
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