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171.
Stanley Kim H Yu Y Snesrud EC Moy LP Linford LD Haas BJ Nierman WC Quackenbush J 《The Plant journal : for cell and molecular biology》2005,41(2):212-220
Previous studies have indicated that Arabidopsis thaliana experienced a genome-wide duplication event shortly before its divergence from Brassica followed by extensive chromosomal rearrangements and deletions. While a large number of the duplicated genes have significantly diverged or lost their sister genes, we found 4222 pairs that are still highly conserved, and as a result had similar functional assignments during the annotation of the genome sequence. Using whole-genome DNA microarrays, we identified 906 duplicated gene pairs in which at least one member exhibited a significant response to oxidative stress. Among these, only 117 pairs were up- or down-regulated in both pairs and many of these exhibited dissimilar patterns of expression. Examination of the expression patterns of PAL1 and PAL2, ACD1 and ACD2, genes coding for two Hsp20s, various P450s, and electron transfer flavoproteins suggests Arabidopsis evolved a number of distinct oxidative stress response mechanisms using similar gene sets following the duplication of its genome. 相似文献
172.
Saikatendu KS Joseph JS Subramanian V Clayton T Griffith M Moy K Velasquez J Neuman BW Buchmeier MJ Stevens RC Kuhn P 《Structure (London, England : 1993)》2005,13(11):1665-1675
The crystal structure of a conserved domain of nonstructural protein 3 (nsP3) from severe acute respiratory syndrome coronavirus (SARS-CoV) has been solved by single-wavelength anomalous dispersion to 1.4 A resolution. The structure of this "X" domain, seen in many single-stranded RNA viruses, reveals a three-layered alpha/beta/alpha core with a macro-H2A-like fold. The putative active site is a solvent-exposed cleft that is conserved in its three structural homologs, yeast Ymx7, Archeoglobus fulgidus AF1521, and Er58 from E. coli. Its sequence is similar to yeast YBR022W (also known as Poa1P), a known phosphatase that acts on ADP-ribose-1'-phosphate (Appr-1'-p). The SARS nsP3 domain readily removes the 1' phosphate group from Appr-1'-p in in vitro assays, confirming its phosphatase activity. Sequence and structure comparison of all known macro-H2A domains combined with available functional data suggests that proteins of this superfamily form an emerging group of nucleotide phosphatases that dephosphorylate Appr-1'-p. 相似文献
173.
Life history and habitat preference in the Darling hardyhead,Craterocephalus amniculus (Teleostei,Atherinidae) in the northern Murray‐Darling Basin,Australia
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The Darling hardyhead, Craterocephalus amniculus (Atherinidae), is a threatened fish species inhabiting upstream reaches of a number of northern Murray‐Darling Basin catchments. Little is known of its life history. Our goal was to determine patterns of seasonal size structure, interannual and spatial variation in diet, and habitat selection in this species across multiple sites and years in the upper Macintyre River, northern New South Wales. Preserved specimens from a separate study were used to obtain information on diet and size structure. Size structures suggested a single annual spawning season in late September or early October. Diets varied significantly, both between years at the downstream site and among the three sites although the underlying cause of this was untested. Dietary diversity increased with distance downstream. At the two upstream sites, aquatic invertebrates made up most of the diet while over half the gut contents at the downstream site was unidentified detritus. Preference was shown for pool habitats with a sand or cobble substrate, increased channel depth and width and distance from the bank, and reduced flow velocity. Overhanging exotic riparian vegetation and in‐stream woody debris were non‐preferred. This species may be vulnerable to further population decline in light of its restricted habitat preferences and narrow spawning season. However, comparable data from nearby catchments will be necessary to ascertain the species’ conservation status across its broader distribution. 相似文献
174.
Franklin J. Moy Michael R. Pisano Pranab K. Chanda Charlotte Urbano Loran M. Killar Mei-Li Sung Robert Powers 《Journal of biomolecular NMR》1997,10(1):9-19
Fibroblast collagenase (MMP-1), a 169-residue protein with amolecular mass of 18.7 kDa, is a matrix metalloproteinase which has beenassociated with pathologies such as arthritis and cancer. The assignments ofthe 1H, 15N, 13CO and13C resonances, determination of the secondary structure andanalysis of 15N relaxation data of the inhibitor-freecatalytic fragment of recombinant human fibroblast collagenase (MMP-1) arepresented. It is shown that MMP-1 is composed of a -sheet consistingof five -strands in a mixed parallel and antiparallel arrangement(residues 13–19, 48–53, 59–65, 82–85 and94–99) and three -helices (residues 27–43, 112–124and 150–160). This is nearly identical to the secondary structuredetermined from the refined X-ray crystal structures of inhibited MMP-1. Themajor difference observed between the NMR solution structure ofinhibitor-free MMP-1 and the X-ray structures of inhibited MMP-1 is thedynamics of the active site. The 2D 15N-1H HSQCspectra, the lack of information in the 15N-edited NOESYspectra, and the generalized order parameters (S2) determinedfrom 15N T1, T2 and NOE datasuggest a slow conformational exchange for residues comprising the activesite (helix B, zinc ligated histidines and the nearby loop region) and ahigh mobility for residues Pro138-Gly144 in thevicinity of the active site for inhibitor-free collagenase. In contrast tothe X-ray structures, only the slow conformational exchange is lost in thepresence of an inhibitor. 相似文献
175.
ARNE MOKSNES EIVIN RØSKAFT LISE GREGER HAGEN MARCEL HONZA CECILIE MØRK PER H. OLSEN 《Ibis》2000,142(2):247-258
This study is based on continuous video recordings made at 53 Reed Warbler Acrocephalus scirpaceus nests each day during the laying period. Egg-laying by the Common Cuckoo Cuculus canorus was recorded in 14 (26.4%) of these nests. By analysing the activity of the host birds around and at the nest, we found that this is probably not the only cue used by the Common Cuckoo when locating suitable nests to parasitize. Furthermore, in most cases there was no significant difference between the length of time the host birds spent at the nest in the morning and afternoon, thus providing little support for the hypothesis that the Common Cuckoo lays in the afternoon because it is less likely to be seen by the nest owners then. Parasitized Reed Warblers rejected the Common Cuckoo egg more frequently when they observed the parasite at their nests. However, contrary to what should be expected, most Common Cuckoos laid their eggs in the presence of the host(s), and in general their egg-laying behaviour (for example duration of stay at the nest) was less secretive than described earlier. When partially depredating host clutches, Cuckoos showed the same behavioural pattern at parasitized and unparasitized nests, indicating that the latter may act as a potential reserve for egg-laying. 相似文献
176.
Patterns of differentiation and hybridization in North American wolflike canids, revealed by analysis of microsatellite loci 总被引:8,自引:0,他引:8
Roy MS; Geffen E; Smith D; Ostrander EA; Wayne RK 《Molecular biology and evolution》1994,11(4):553-570
Genetic divergence and gene flow among closely related populations are
difficult to measure because mutation rates of most nuclear loci are so low
that new mutations have not had sufficient time to appear and become fixed.
Microsatellite loci are repeat arrays of simple sequences that have high
mutation rates and are abundant in the eukaryotic genome. Large population
samples can be screened for variation by using the polymerase chain
reaction and polyacrylamide gel electrophoresis to separate alleles. We
analyzed 10 microsatellite loci to quantify genetic differentiation and
hybridization in three species of North American wolflike canids. We
expected to find a pattern of genetic differentiation by distance to exist
among wolflike canid populations, because of the finite dispersal distances
of individuals. Moreover, we predicted that, because wolflike canids are
highly mobile, hybrid zones may be more extensive and show substantial
changes in allele frequency, relative to nonhybridizing populations. We
demonstrate that wolves and coyotes do not show a pattern of genetic
differentiation by distance. Genetic subdivision in coyotes, as measured by
theta and Gst, is not significantly different from zero, reflecting
persistent gene flow among newly established populations. However, gray
wolves show significant subdivision that may be either due to drift in past
Ice Age refugia populations or a result of other causes. Finally, in areas
where gray wolves and coyotes hybridize, allele frequencies of gray wolves
are affected, but those of coyotes are not. Past hybridization between the
two species in the south-central United States may account for the origin
of the red wolf.
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177.
178.
Neutron‐based computed microtomography: Pliobates cataloniae and Barberapithecus huerzeleri as a test‐case study
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179.
Structure-function studies of murine epidermal growth factor: expression and site-directed mutagenesis of epidermal growth factor gene 总被引:3,自引:0,他引:3
P Ray F J Moy G T Montelione J F Liu S A Narang H A Scheraga R Wu 《Biochemistry》1988,27(19):7289-7295
Wild-type murine epidermal growth factor (mEGF) and mutants with Leu47 replaced by serine and valine, respectively, have been produced by recombinant DNA methodology. A synthetic gene for mEGF was fused to the coding sequence for the signal peptide of the outer membrane protein A (ompA) of Escherichia coli in the secretion vector pIN-III-ompA3, and the recombinant plasmid was used to transform E. coli. Upon induction of gene expression, mEGF and the mutants was expressed and secreted into the periplasmic space. Purification of the wild-type Leu47-mEGF and the mutants was carried out by reversed-phase and anion-exchange high-performance liquid chromatography (HPLC). Amino acid analysis and Western blot analysis further confirmed the identities of the proteins. Specific activities for wild-type and mutant proteins were measured in both mEGF receptor binding and autophosphorylation assays. The recombinant mEGF has specific activities identical with that of mEGF purified from mouse submaxillary glands, while both mutants have reduced specific activities in both bioassays. The data demonstrate the importance of the highly conserved Leu47 residue in mEGF for full biological activity. 相似文献
180.
The solidification front technique is employed to determine the surface tension of fixed erythrocytes of dog, horse, human, chicken, and turkey. The results range from 65.5 erg/cm2 for dog erythrocytes to 67.6 erg/cm2 for turkey erythrocytes. A detailed error analysis shows that the differences obtained are statistically significant. Since cellular interactions are governed to a considerable extent by surface tension effects, it is concluded that caution needs to be exercised when results obtained for one species are used to predict the behavior of cells of another species. 相似文献