Abstract:
:Some trypanosomatid protozoa (order Kinetoplastida) are well known to harbor bacterial endosymbionts. Their phylogenetic positions and evolutionary relationships with the hosts were deduced by comparing the rRNA gene sequences. Earlier, we observed that these symbionts from three Crithidia spp. are identical and are closely related to Bordetella bronchiseptica. We have now sequenced the genes of another endosymbiont and the host protozoan Blastocrithidia culicis. The 16S rRNA genes of the Blastocrithidia and Crithidia symbionts share approximately 97% identity and form a distinct group, branching off the B. bronchiseptica lineage in the beta-division of Proteobacteria. Comparison of their secondary structures in the stem regions suggests compensatory mutations of the symbiont sequences, contributing to their biased base transitions from G to A and C to T. Two putative genes encoding tRNA(Ile) and tRNA(Ala) are highly conserved in the otherwise variable internal transcribed spacer region. Comparisons of the host rRNA gene sequences suggest that the symbiont-containing Crithidia and Blastocrithidia are more akin to each other than to other trypanosomatids. The evidence suggests that Blastocrithidia and Crithidia symbionts descend from a common ancestor, which had presumably entered an ancestral host and thence coevolved with it into different species. We therefore propose naming the symbionts Kinetoplastibacterium blastocrithidii and Kinetoplastibacterium crithidii.
journal_name
Proc Natl Acad Sci U S Aauthors
Du Y,Maslov DA,Chang KPdoi
10.1073/pnas.91.18.8437subject
Has Abstractpub_date
1994-08-30 00:00:00pages
8437-41issue
18eissn
0027-8424issn
1091-6490journal_volume
91pub_type
杂志文章abstract::γ-Secretase is an intramembrane-cleaving protease responsible for the generation of amyloid-β (Aβ) peptides. Recently, a series of compounds called γ-secretase modulators (GSMs) has been shown to decrease the levels of long toxic Aβ species (i.e., Aβ42), with a concomitant elevation of the production of shorter Aβ spe...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1402171111
更新日期:2014-07-22 00:00:00
abstract::Maleyl bovine plasma albumin competed on an equimolar basis with malondialdehyde low density lipoprotein (LDL) in suppressing the lysosomal hydrolysis of 125I-labeled malondialdehyde LDL mediated by the scavenger receptor of human monocyte macrophages. Maleyl bovine plasma albumin, in which 94% of the amino groups wer...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.82.9.2693
更新日期:1985-05-01 00:00:00
abstract::We introduce a quantitative framework for assessing the generation of crossovers in DNA shuffling experiments. The approach uses free energy calculations and complete sequence information to model the annealing process. Statistics obtained for the annealing events then are combined with a reassembly algorithm to infer...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.051631498
更新日期:2001-03-13 00:00:00
abstract::Discrete growing spiral modes are calculated, on the basis of principles of stellar dynamics, according to the recently developed asymptotic theory of density waves for spiral structure in galaxies. From the growth rates obtained, it appears likely that several spiral modes coexist in a given disk galaxy. General prop...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.74.11.4726
更新日期:1977-11-01 00:00:00
abstract::Proteins fold through a variety of mechanisms. For a given protein, folding routes largely depend on the protein's stability and its native-state geometry, because the landscape is funneled. These ideas are corroborated for cytochrome c by using a coarse-grained topology-based model with a perfect funnel landscape tha...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0505274102
更新日期:2005-08-30 00:00:00
abstract::We have examined the 270 MHz nuclear magnetic resonance spectrum and relaxation kinetic behavior of tRNA2Glu (E. coli) in the absence of Mg++, a condition which produces an inactive form of this tRNA. The results show that the denatured form has about five fewer proton resonances in the region from -12 to -15 ppm. Rel...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.73.7.2216
更新日期:1976-07-01 00:00:00
abstract::It has been hypothesized that penicillin acts as a structural analog of the acyl-D-alanyl-D-alanine terminus of nascent bacterial cell wall and that it consequently binds to and acylates the active site of the enzyme(s) that crosslinks the cell wall to form an inactive penicilloyl enzyme [Tipper, D.J. & Strominger, J....
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.76.6.2730
更新日期:1979-06-01 00:00:00
abstract::Heme is a common factor linking several metabolic perturbations in Alzheimer's disease (AD), including iron metabolism, mitochondrial complex IV, heme oxygenase, and bilirubin. Therefore, we determined whether heme metabolism was altered in temporal lobes obtained at autopsy from AD patients and age-matched nondemente...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0404349101
更新日期:2004-07-27 00:00:00
abstract::Antiapoptotic Bcl-2 family members interact with inositol trisphosphate receptor (InsP3R) Ca(2+)release channels in the endoplasmic reticulum to modulate Ca(2+)signals that affect cell viability. However, the molecular details and consequences of their interactions are unclear. Here, we found that Bcl-xL activates sin...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1517935113
更新日期:2016-03-29 00:00:00
abstract::Mouse blastocyst functions have been shown to be disrupted by in vitro exposure to N-methyl-N-nitrosourea (MeNU). After exposure, the chemically treated blastocysts were transferred to the uteri of pseudopregnant surrogate mothers. Implantation rate and birth rate have been shown previously to decrease in a concentrat...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.82.24.8757
更新日期:1985-12-01 00:00:00
abstract::T-cell anergy is a state of T cells that is hyporesponsive to stimulation via the T-cell receptor and costimulatory molecules and is thought to be important for self-tolerance. How T-cell anergy is regulated is still poorly understood. We report here that tuberous sclerosis (TSC)1 is critical for T-cell anergy. Defici...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1119744109
更新日期:2012-08-28 00:00:00
abstract::A preparative two-dimensional polyacrylamide gel system was used to separate and purify the major Coomassie blue-stained proteins from the isolated rat liver nuclear matrix. Approximately 12 major proteins were consistently found. Of these, 5 proteins represented identified proteins, including nuclear lamins A, B, and...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.88.22.10312
更新日期:1991-11-15 00:00:00
abstract::The total amount of noncoding sequences on chromosomes of contemporary organisms varies significantly from species to species. We propose a hypothesis for the origin of these noncoding sequences that assumes that (i) an approximately equal to 0.55-kilobase (kb)-long reading frame composed the primordial gene and (ii) ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.84.17.6195
更新日期:1987-09-01 00:00:00
abstract::Design and synthesis of 3D metallic carbon that is stable under ambient conditions has been a long-standing dream. We predict the existence of such phases, T6- and T14-carbon, consisting of interlocking hexagons. Their dynamic, mechanical, and thermal stabilities are confirmed by carrying out a variety of state-of-the...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1311028110
更新日期:2013-11-19 00:00:00
abstract::A fraction of mouse RNA containing messenger RNA coding for mouse interferon was translated with high efficiency in a wheat germ system into a fully active product. This product fulfills the criteria for mouse interferon, namely: (1) it was active against vesicular stomatitis virus and herpes simplex virus in mouse ce...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.72.10.3975
更新日期:1975-10-01 00:00:00
abstract::Information concerning the dynamics of river meandering is embedded in their planforms. Here, we focus on how bend skewing varies with increasing sinuosity, and how flow direction is embedded in bend skewing. It has often been thought that upstream-skewed bends are dominant within a sufficiently long reach. These bend...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1910874116
更新日期:2019-11-19 00:00:00
abstract::The determination of macromolecular structures requires weighting of experimental evidence relative to prior physical information. Although it can critically affect the quality of the calculated structures, experimental data are routinely weighted on an empirical basis. At present, cross-validation is the most rigorou...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0506412103
更新日期:2006-02-07 00:00:00
abstract::Many neurodegenerative diseases are characterized by the accumulation of amyloid fibers in the brain, which can occur when a protein misfolds into an extended beta-sheet conformation. The nucleation of these beta-sheet aggregates is of particular interest, not only because it is the rate-determining step toward fiber ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0502804102
更新日期:2005-10-04 00:00:00
abstract::Tubular membrane structures are widespread in eukaryotic cells, but the mechanisms underlying their formation and stability are not well understood. Previous work has focused on tube extrusion from cells and model membranes under the application of external forces. Here, we present novel membrane/polymer systems, wher...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1015892108
更新日期:2011-03-22 00:00:00
abstract::Recent studies have shown that orthotopic (transurethral) transplantation of human bladder cancer cell lines into nude mice permits tumor growth that accurately reflects their clinical malignant status in the original host. Thus, such a system allows a unique opportunity to analyze the genetic events involved in the c...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.87.22.9047
更新日期:1990-11-01 00:00:00
abstract::A major challenge in interpreting genome sequences is understanding how the genome encodes the information that specifies when and where a gene will be expressed. The first step in this process is the identification of regions of the genome that contain regulatory information. In higher eukaryotes, this cis-regulatory...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.231608898
更新日期:2002-01-22 00:00:00
abstract::Mammalian homologues of Drosophila Trp form plasma membrane channels that mediate Ca(2+) influx in response to activation of phospholipase C and internal Ca(2+) store depletion. Previous studies showed that human Trp3 is activated by inositol 1,4,5-trisphosphate (IP(3)) receptors (IP(3)Rs) and identified interacting d...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.051632698
更新日期:2001-03-13 00:00:00
abstract::Two-dimensional gel electrophoresis of immunoprecipitated human HLA-DR antigens from cells expressing the HLA-DR4 haplotype shows distinct clustering of beta-chain patterns. Six unique electrophoretic variants were observed among 17 HLA-DR4 homozygous cell lines (HCL) analyzed. These patterns correlate precisely with ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.80.22.6962
更新日期:1983-11-01 00:00:00
abstract::Soil systems are being increasingly exposed to the interactive effects of biological invasions and climate change, with rising temperatures expected to benefit alien over indigenous species. We assessed this expectation for an important soil-dwelling group, the springtails, by determining whether alien species show br...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1715598115
更新日期:2018-01-02 00:00:00
abstract::The adenosine deaminases that act on RNA (ADARs) catalyze the site-specific conversion of adenosine to inosine (A to I) in primary mRNA transcripts, thereby affecting the splicing pattern or coding potential of mature mRNAs. Although the subnuclear localization of A-to-I editing has not been precisely defined, ADARs h...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.2336131100
更新日期:2003-11-25 00:00:00
abstract::Polycomb group genes (PcGs) have been implicated in cancer based on altered levels of expression observed in certain tumors and the behavior of cultured cells containing inserted PcG transgenes. Endometrial stromal tumors provide evidence for a direct causal relationship because they contain several chromosomal transl...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0709986104
更新日期:2007-12-11 00:00:00
abstract::Generating human single-nucleotide polymorphisms (SNPs) is no longer a rate-limiting step for genetic studies of disease. The number of SNPs in public databases already exceeds 200,000, and the total is expected to exceed 1,000,000 within a year. Rather, progress is limited by the inability to genotype large numbers o...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.210394597
更新日期:2000-10-24 00:00:00
abstract::Ciliary Neurotrophic Factor (CNTF) was first characterized as a trophic factor for motor neurons in the ciliary ganglion and spinal cord, leading to its evaluation in humans suffering from motor neuron disease. In these trials, CNTF caused unexpected and substantial weight loss, raising concerns that it might produce ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.061034298
更新日期:2001-04-10 00:00:00
abstract::In that salmonellae have been implicated in an unprecedented array of diseases, sequences found to be specific to this species are often thought to be involved in the virulence attributes not seen in other enteric bacteria. To identify the molecular, genetic, and phenotypic characteristics that differentiate bacterial...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.90.3.1033
更新日期:1993-02-01 00:00:00
abstract::Astrocytes regulate synaptic transmission through controlling neurotransmitter concentrations around synapses. Little is known, however, about their roles in neural circuit development. Here we report that Bergmann glia (BG), specialized cerebellar astrocytes that thoroughly enwrap Purkinje cells (PCs), are essential ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1617330114
更新日期:2017-07-11 00:00:00