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31.
32.
Leslie F. Lock Debra J. Gilbert Valerie A. Street Mary B. Migeon Nancy A. Jenkins Neal G. Copeland Bruce L Tempel 《Genomics》1994,20(3)
Cloning of the Drosophila Shaker gene established that a neurological phenotype including locomotor dysfunction can be caused by a mutation in a voltage-gated potassium (K) channel gene. Shaker sequences have been used to isolate a large family of related K channel genes from both flies and mammals. Toward elucidating the evolutionary relationship between loci and the potential causal connection that K channels may have to mammalian genetic disorders, we report here the genetic mapping of 12-16 different murine, voltage-gated K channel genes. We find that multiple genes, in some cases from distantly related K channel subfamilies, occur in clusters in the mouse genome. These mapping results suggest that the K channel gene subfamilies arose through ancient localized gene duplication events, followed by chromosomal duplications and rearrangements as well as further gene duplication. We also note that several neurologic disorders of both mouse and human are associated with the chromosomal regions containing K channel genes. 相似文献
33.
C. David Pauza Peter Emau Maria S. Salvato Parul Trivedi Debra MacKenzie Miroslav Malkovsky Hideo Uno Kevin T. Schultz 《Journal of medical primatology》1993,22(2-3):154-161
Intrarectal inoculation of rhesus monkeys with low doses of SIVmac led to a prolonged clinical and virological latency that was not observed for high intrarectal doses or for intravenous inoculation. Animals infected intrarectally with low virus doses remained negative for serum antibody responses to SIV for at least one year even though they readily transferred SIV to naive recipients via transfusion of whole blood. 相似文献
34.
C M Read P D Cary C Crane-Robinson P C Driscoll D G Norman 《Nucleic acids research》1993,21(15):3427-3436
We have determined the tertiary structure of box 2 from hamster HMG1 using bacterial expression and 3D NMR. The all alpha-helical fold is in the form of a V-shaped arrowhead with helices along two edges and one rather flat face. This architecture is not related to any of the known DNA binding motifs. Inspection of the fold shows that the majority of conserved residue positions in the HMG box family are those involved in maintaining the tertiary structure and thus all homologous HMG boxes probably have essentially the same fold. Knowledge of the tertiary structure permits an interpretation of the mutations in HMG boxes known to abrogate DNA binding and suggests a mode of interaction with bent and 4-way junction DNA. 相似文献
35.
36.
Class I molecules of the major histocompatibility complex (MHC) bind peptides derived from cytoplasmic proteins. Comparison of over 100 such peptides reveals the importance of the carboxy-terminal residue in selective binding. Recent evidence implicates the proteases and transporters of the processing pathway in providing peptides with the correct residues at the carboxyl terminus. 相似文献
37.
Florence W. L. Tsui Hing-Wo Tsui Samuel Mok Irena Mlinaric Neal G. Copeland Debra J. Gilbert Nancy A. Jenkins Katherine A. Siminovitch 《Genomics》1993,15(3)
Stefins or Type 1 cystatins belong to a large, evolutionarily conserved protein superfamily, the members of which inhibit the papain-like cysteine proteinases. We report here on the molecular cloning and chromosomal localization of three newly identified members of the murine stefin gene family. These genes, designated herein as mouse stefins 1, 2, and 3, were isolated on the basis of their relatively increased expression in moth-eaten viable compared to normal congenic mouse bone marrow cells. The open reading frames of the stefin cDNAs encode proteins of approximately 11.5 kDa that show between 50 and 92% identity to sequences of stefins isolated from various other species. Data from Southern analysis suggest that the murine stefin gene family encompasses at least 6 and possibly 10-20 members, all of which appear to be clustered in the genome. Analysis of interspecific backcross mice indicates that the genes encoding the three mouse stefins all map to mouse chromosome 16, a localization that is consistent with the recent assignment of the human stefin A gene to a region of conserved homology between human chromosome 3q and the proximal region of mouse chromosome 16. 相似文献
38.
Debra A. Waters Mark A. Buchheim Richard A. Dewey Russell L. Chapman 《American journal of botany》1992,79(4):459-466
Ribosomal RNA sequences and cladistic analysis were used to infer a phylogeny for eight bryophyte taxa. Portions of the cytoplasmic large (26S-like) and small (18S-like) subunit ribosomal RNA genes were sequenced for three marchantioid liverworts (Asterella, Conocephalum, and Riccia), three mosses (Atrichum, Fissidens, and Plagiomnium), and two hornworts (Phaeoceros and Notothylas). Cladistic analysis of these data suggests that the hornworts are the sister group to the mosses, the mosses and hornworts form a clade that is sister to the tracheophytes, and the liverworts form a clade sister to the other land plants. These results differ from previous cladistic analyses based on morphology, ultrastructure, and biochemistry, wherein the mosses alone are sister group to the tracheophytes. We conclude that cladistic analysis of molecular data can provide an independent data set for the study of bryophyte phylogeny, but the differences between the molecular and morphological results are a topic for further investigation. 相似文献
39.
Debra A. Willard 《American journal of botany》1989,76(10):1429-1440
Spores were extracted from Carboniferous Lepidostrobus compressions in order to associate in situ microspores with dispersed species of Lycospora. Two hundred twenty-six cones were examined, of which 61 contained spores. Fertile cones came from the Westphalian D of England, Namurian B through Westphalian D of the Appalachian and Illinois basins, and the Westphalian D of the Western Interior. Cones were separated into species based on microspore and cone morphology. Lycospora trigonoreticulata was produced by Lepidostrobus princeps from Westphalian C-D rocks from Missouri, the Illinois Basin, and the Appalachian Basin. Lycospora rotunda was produced by Lepidostrobus sp. A from Westphalian A rocks of Alabama. Two cone species produced Lycospora torquifer: Lepidostrobus praelongus from the Westphalian D of Pennsylvania and Lepidostrobus variabilis from the Westphalian A and C of the Illinois and Appalachian basins. Lycospora punctata was produced by Lepidostrobus cf. squarrosus from the Westphalian D of England, the Appalachian Basin, and Illinois Basin. Lycospora noctuina was produced by Lepidostrobus haslingdenensis from the Namurian B/C of Illinois. Microspore species are differentiated primarily on the basis of size, cingulum structure and width, and ornamentation. Cone species differ in width and distal lamina size, shape, and attitude. Lycospora species isolated from clastic species of Lepidostrobus differ completely from those of coal-swamp species, confirming that lycopod trees from clastic environments represent biologically different species from those centered in coal swamps. 相似文献
40.
Molecular and expression analysis of the Rhizobium meliloti phosphoenolpyruvate carboxykinase (pckA) gene. 总被引:6,自引:4,他引:2 下载免费PDF全文
The pckA gene of Rhizobium meliloti, encoding phosphoenolpyruvate carboxykinase, was isolated from a genomic cosmid library by complementation of the succinate growth phenotype of a Pck- mutant. The gene region was mapped by subcloning and Tn5 insertion mutagenesis. The DNA sequence for a 2-kb region containing the structural gene and its promoter was determined. The pckA gene encodes as 536-amino-acid protein that shows homology with other ATP-dependent Pck enzymes. The promoter was identified following primer extension analysis and is similar to sigma 70-like promoters. Expression analysis with a pckA::lacZ gene fusion indicated that the pckA gene was strongly induced at the onset of stationary phase in complex medium. When defined carbon sources were tested, the expression level of the pckA gene was found to be high when cells were grown in minimal media with succinate or arabinose as the sole carbon source but almost absent when glucose, sucrose, or glycerol was the sole carbon source. Glucose and sucrose were not found to strongly repress pckA induction by succinate. 相似文献