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71.
72.
Free and bound amino acids and proteins in developing grains of rice with enhanced lysine/proteins 总被引:2,自引:0,他引:2
G. W. Schaeffer F. T. Sharpe 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1997,94(6-7):878-881
Free amino acids were determined in developing seed of a rice mutant with enhanced grain lysine. This phenotype frequently
has enhanced protein. Some free amino acids of developing seed are inversely related to the level of total amino acids in
proteins of the mature grain. Amino acids that were enhanced in protein, including aspartic acid, threonine, methionine and
lysine, were notably lower in the free amino-acid pool. Our conclusion is that mutant-developing grains process aspartate
amino acids more rapidly than the controls. Conversely, arginine, valine and glutamic acid/glutamine accumulate as free amino
acids with mutant/control ratios of 1.39, 1.29 and 1.12, respectively. Glutamic acid/glutamine in proteins of mature seeds
is lower in the mutant than the control. 3H-lysine incorporation showed enhanced isotope incorporation into at least four proteins. One mutant protein was less actively
labelled than analogous controls. The 3Hlysine pattern indicates processing modifications in this useful rice mutant.
Received: 14 October 1996/Accepted: 8 November 1996 相似文献
73.
Timothy N. Schaeffer G. Jason Smith Michael S. Foster Anthony DeTomaso 《Journal of phycology》2002,38(6):1090-1098
Unattached, nongeniculate, coralline algae or rhodoliths exhibit a range of morphological variability seemingly dependent on environmental factors. Rhodoliths have an extensive fossil record, and environmentally dependent characteristics make them potentially reliable paleoindicators. Species of the rhodolith‐forming genus Lithophyllum Philippi in Baja California Sur, Mexico were recently consolidated into one species. Under the new classification, L. margaritae (Hariot) Heydrich consists of several growth forms presumably reflecting local environmental conditions. We examined the genetic structure of four populations of this species using amplified fragment length polymorphisms (AFLP) to characterize the extent of genetic variation associated with foliose and fruticose growth forms. AFLP band sharing analysis revealed that foliose growth forms exhibited consistently higher intrapopulation similarities (0.75–0.85) than fruticose growth forms (similarity range, 0.55–0.67). This trend was also evident in comparisons of geographically isolated populations. These data indicate that the two morphologies are genetically distinct and that genetic exchange between foliose and fruticose growth forms of L. margaritae may be limited. Consequently, rhodolith growth forms appear to be the result of an interplay between both genetic makeup and environmental conditions. 相似文献
74.
J.E. Shade B.V. Johnson D.H. Gibson W.-L. Hsu C.D. Schaeffer Jr. 《Inorganica chimica acta》1985,99(1):99-102
Irradiation of M(CO)6 (M = Mo. W) and Sn[N(SiMe3)2]2 in hexane with UV light results in carbonyl substitution to form both M(CO)5Sn[N(SiMe3)2]2 and M(CO)4Sn[N(SiMe3)2]2)2 complexes. The M(CO)4L2 species present the first examples in which both cis and trans isomers have been observed upon substitution of bulky divalent main group IV ligands. The highly air-sensitive W(CO)5L and W(CO)4L2 complexes have been isolated. 相似文献
75.
76.
Coulbault L Deslandes B Herlicoviez D Read MH Leporrier N Schaeffer S Mouadil A Lombès A Chapon F Jauzac P Allouche S 《Biochemical and biophysical research communications》2007,362(3):601-605
We describe a young woman who presented with a progressive myopathy since the age of 9. Spectrophotometric analysis of the respiratory chain in muscle tissue revealed combined and profound complex I, III, II+III, and IV deficiency ranging from 60% to 95% associated with morphological and histochemical abnormalities of the muscle. An exhaustive screening of mitochondrial transfer and ribosomal RNAs showed a novel G>A substitution at nucleotide position 3090 which was detected only in urine sediment and muscle of the patient and was not found in her mother's blood cells and urine sample. We suggest that this novel de novo mutation in the 16S ribosomal RNA, a nucleotide which is highly conserved in different species, would impair mitochondrial protein synthesis and would cause a severe myopathy. 相似文献
77.
M E Goldberg F Schaeffer Y Guillou L Djavadi-Ohaniance 《The Journal of biological chemistry》1999,274(23):16052-16061
When beef heart apocytochrome c is unfolded, it folds upon noncovalent heme binding (Dumont, M. E., Corin, A. F., and Campbell, G.A. (1994) Biochemistry, 33, 7368-7378). Here, the conformation of the heme-apocytochrome noncovalent complex is compared with that of holocytochrome c. A purification method was designed for obtaining in large amounts apocytochrome c that was shown by amino acid analysis and mass spectroscopy to be chemically intact. The apoprotein and its noncovalent complex were characterized by absorption, fluorescence, circular dichroism, and sedimentation velocity, confirming previous reports. Sedimentation-diffusion equilibrium showed that the apoprotein and its noncovalent complex with heme were monomeric. Surprisingly, whereas apocytochrome c was quite soluble, the noncovalent complex slowly formed heavy aggregates, thus precluding experiments at the concentrations needed for structural studies. Two monoclonal antibodies that bind strongly to distinct antigenic sites on native holocytochrome were used to probe the noncovalent complex conformation. For both antibodies, the affinity for the noncovalent complex was only about 5-10-fold smaller than that for native holocytochrome c, and about 50-100-fold larger than that for apocytochrome c. These results indicate that the noncovalent complex, although not entirely native, carries some pseudo-native structural motifs. 相似文献
78.
rlk/TXK Encodes Two Forms of a Novel Cysteine String Tyrosine Kinase Activated by Src Family Kinases 总被引:7,自引:1,他引:6 下载免费PDF全文
Jayantha Debnath Mario Chamorro Michael J. Czar Edward M. Schaeffer Michael J. Lenardo Harold E. Varmus Pamela L. Schwartzberg 《Molecular and cellular biology》1999,19(2):1498-1507
Rlk/Txk is a member of the BTK/Tec family of tyrosine kinases and is primarily expressed in T lymphocytes. Unlike other members of this kinase family, Rlk lacks a pleckstrin homology (PH) domain near the amino terminus and instead contains a distinctive cysteine string motif. We demonstrate here that Rlk protein consists of two isoforms that arise by alternative initiation of translation from the same cDNA. The shorter, internally initiated protein species lacks the cysteine string motif and is located in the nucleus when expressed in the absence of the larger form. In contrast, the larger form is cytoplasmic. We show that the larger form is palmitoylated and that mutation of its cysteine string motif both abolishes palmitoylation and allows the protein to migrate to the nucleus. The cysteine string, therefore, is a critical determinant of both fatty acid modification and protein localization for the larger isoform of Rlk, suggesting that Rlk regulation is distinct from the other Btk family kinases. We further show that Rlk is phosphorylated and changes localization in response to T-cell-receptor (TCR) activation and, like the other Btk family kinases, can be phosphorylated and activated by Src family kinases. However, unlike the other Btk family members, Rlk is activated independently of the activity of phosphatidylinositol 3-kinase, consistent with its lack of a PH domain. Thus, Rlk has two distinct isoforms, each of which may have unique properties in signaling downstream from the TCR. 相似文献
79.
Broca's area, a cerebral cortical area located in the inferior frontal gyrus (IFG) of the human brain, has been identified as one of several critical regions associated with the motor planning and execution of language. Anatomically, Broca's area is most often larger in the left hemisphere, and functional imaging studies in humans indicate significant left-lateralized patterns of activation during language-related tasks. If, and to what extent, nonhuman primates, particularly chimpanzees, possess a homologous region that is involved in the production of their own communicative signals remains unknown. Here, we show that portions of the IFG as well as other cortical and subcortical regions in chimpanzees are active during the production of communicative signals. These findings are the first to provide direct evidence of the neuroanatomical structures associated with the production of communicative behaviors in chimpanzees. Significant activation in the left IFG in conjunction with other cortical and subcortical brain areas during the production of communicative signals in chimpanzees suggests that the neurological substrates underlying language production in the human brain may have been present in the common ancestor of humans and chimpanzees. 相似文献
80.
Chromosomal rearrangement inferred from comparisons of 12 Drosophila genomes 总被引:1,自引:0,他引:1 下载免费PDF全文
The availability of 12 complete genomes of various species of genus Drosophila provides a unique opportunity to analyze genome-scale chromosomal rearrangements among a group of closely related species. This article reports on the comparison of gene order between these 12 species and on the fixed rearrangement events that disrupt gene order. Three major themes are addressed: the conservation of syntenic blocks across species, the disruption of syntenic blocks (via chromosomal inversion events) and its relationship to the phylogenetic distribution of these species, and the rate of rearrangement events over evolutionary time. Comparison of syntenic blocks across this large genomic data set confirms that genetic elements are largely (95%) localized to the same Muller element across genus Drosophila species and paracentric inversions serve as the dominant mechanism for shuffling the order of genes along a chromosome. Gene-order scrambling between species is in accordance with the estimated evolutionary distances between them and we find it to approximate a linear process over time (linear to exponential with alternate divergence time estimates). We find the distribution of synteny segment sizes to be biased by a large number of small segments with comparatively fewer large segments. Our results provide estimated chromosomal evolution rates across this set of species on the basis of whole-genome synteny analysis, which are found to be higher than those previously reported. Identification of conserved syntenic blocks across these genomes suggests a large number of conserved blocks with varying levels of embryonic expression correlation in Drosophila melanogaster. On the other hand, an analysis of the disruption of syntenic blocks between species allowed the identification of fixed inversion breakpoints and estimates of breakpoint reuse and lineage-specific breakpoint event segregation. 相似文献