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Y Pei

Publications and source records attributed to Y Pei.

At least 19 recordsLinked to original sources
PubMed2006

Cloning and molecular characterization of three novel LMW-i glutenin subunit genes from cultivated einkorn (Triticum monococcum L.).

Three novel low molecular weight (LMW) glutenin subunits from cultivated einkorn (Triticum monococcum L., A(m)A(m), 2n = 2x = 14) were characterized by SDS-PAGE and molecular weights determined by MALDI-TOF-MS. Their coding genes were amplified and cloned with designed AS-PCR primers, revealing three complete gene sequences. All comprised upstream, open reading frame (ORF), downstream and no introns were present. The deduced amino acid sequences showed that all three genes, named as LMW-M1, LMW-M3 and LMW-M5, respectively, belonged to the LMW-i type subunits with the predicted molecular weight between 38.5206 and 38.7028 kDa. They showed high similarity with other LMW-i type genes from hexaploid bread wheats, but also displayed unique features. Particularly, LMW-M5 subunit contained an extra cysteine residue in the C-terminus except for eight conserved cysteines, which resulted from a single-nucleotide polymorphism (SNP) of the T-C transition, namely arginine --> cysteine substitution at position 242 from the N-terminal end. This is the first report that the LMW-i subunit contained nine cysteines residues that could result in a more highly cross-linked and more elastic glutenin suggesting that LMW-M5 gene may associates with good quality properties. In addition, a total of 25 SNPs and one insertions/deletions (InDels) were detected among three LMW-i genes, which could result in significant functional changes in polymer formation of gluten. It is anticipated that these SNPs could be used as reliable genetic markers during wheat quality improvement. The phylogenetic analysis indicated that LMW-i type genes apparently differed from LMW-m and LMW-s type genes and diverged early from the primitive LMW-GS gene family, at about 12.92 million years ago (MYA) while the differentiation of A(m) and A genomes was estimated at 3.98 MYA.

Amino Acid Sequence↗
PubMed2006

Mitochondrial DNA deletions in primate embryonic and adult stem cells.

Mitochondrial DNA (mtDNA) mutations occur naturally in skeletal muscle fibers from aged rhesus macaques. In addition, mtDNA mutations have been observed in germinal vesicle oocytes from fertile monkeys. The goal of this study was to determine whether the rhesus macaque mitochondrial common deletion was present in oocytes and embryos generated by in-vitro embryo production (IVP), as well as in rhesus adult and embryonic stem cell lines. The rhesus common deletion was detected in IVP-generated embryos, three IVP-derived embryonic stem cell lines (ORMES 1, 2 and 7), one in-vivo-derived embryonic stem cell line (R4) and multiple passages of an adult bone marrow stromal cell (BMSC) line. Mitochondrial DNA from an adult adipose stromal cell (ATSC) line was compared with mtDNA from an immortalized line transfected with a retroviral vector expressing telomerase, ATSC-TERT. Multiple passages of the ATSC line harboured a dramatically higher level of the rhesus common deletion than the immortalized ATSC-TERT line. Accumulation of mtDNA mutations in oocytes, embryos and subsequent embryonic stem cell lines, as well as adult stem cell lines, may contribute to mitochondrial dysfunction, and thereby impair ATP production. The authors believe this information establishes a compelling argument for the parallel development of embryonic stem cell technology in non-human primates and humans.

Animals↗
PubMed2005

Ectopic expression of the human adenine nucleotide translocase, isoform 3 (ANT-3). Characterization of ligand binding properties.

The adenine nucleotide translocase (ANT) is a key component in maintaining cellular energy homeostasis, and has also been implicated in formation of the mitochondrial permeability transition pore. Human ANT-3 was cloned from a human heart cDNA library and expressed as a histidine-tagged fusion protein in the mitochondria of the Trichoplusia ni. cell line. Overexpression resulted in a concomitant decrease in the endogenous ANT content, allowing for the characterization of binding of known ANT ligands to the human protein. Binding affinities for bongkrekic acid (BKA), ADP, and atractyloside (ATR) were measured in mitochondria from the human ANT-3 expressing cell line, and compared to similar preparations from bovine heart mitochondria by use of a novel radioiodinated derivative of ATR. Binding to ANT-3 by the high affinity inhibitors BKA and ATR, as well as the lower affinity natural ligand ADP, was similar to that measured in bovine heart mitochondria, and to that previously reported for mammalian heart mitochondria. Characterizations such as these of human ANT isoforms may lead to drug development for enhanced mitochondrial function and cellular viability.

Adenine Nucleotide Translocator 3↗
PubMed2001

The platelet-activating factor receptor protects epidermal cells from tumor necrosis factor (TNF) alpha and TNF-related apoptosis-inducing ligand-induced apoptosis through an NF-kappa B-dependent process.

A number of chemical mediators can induce human keratinocytes and epidermal-derived carcinomas to undergo apoptosis, or programmed cell death. Recent evidence suggests pro-inflammatory cytokines, such as interleukin-1 beta or transforming growth factor alpha, protects carcinomas from numerous pro-apoptotic stimuli. Platelet-activating factor (1-alkyl-2-acetyl-3-glycerophosphocholine; PAF) is a lipid mediator with pro-inflammatory effects on numerous cell types. Although PAF can be metabolized to other bioactive lipids, the majority of PAF effects occur through activation of a G protein-coupled receptor. Using a model system created by retroviral transduction of the PAF receptor (PAF-R) into the PAF-R-negative human epidermal cell line KB and the PAF-R-expressing keratinocyte cell line HaCaT, we now demonstrate that activation of the epidermal PAF-R results in protection from apoptosis induced by tumor necrosis factor (TNF) alpha or TNF-related apoptosis-inducing ligand. The PAF-mediated protection was inhibited by PAF-R antagonists, and protection did not occur in PAF-R-negative KB cells. Additionally, we show protection from TNFalpha- or TRAIL-induced apoptosis by PAF-R activation is dependent on the transcription factor nuclear factor (NF)-kappa B, because PAF-R activation-induced NF-kappa B and epidermal cells transduced with a super-repressor form of inhibitor kappa B were not protected by the PAF-R. These studies provide a mechanism whereby the epidermal PAF-R, and possibly other G protein-coupled receptors, can exert anti-apoptotic effects through an NF-kappa B-dependent process.

Apoptosis↗
PubMed2001

RNA triphosphatase is essential in Schizosaccharomyces pombe and Candida albicans.

BACKGROUND: The first two steps in the capping of cellular mRNAs are catalyzed by the enzymes RNA triphosphatase and RNA guanylyltransferase. Although structural and mechanistic differences between fungal and mammalian RNA triphosphatases recommend this enzyme as a potential antifungal target, it has not been determined if RNA triphosphatase is essential for the growth of fungal species that cause human disease. RESULTS: We show by classical genetic methods that the triphosphatase (Pct1) and guanylyltransferase (Pce1) components of the capping apparatus in the fission yeast Schizosaccharomyces pombe are essential for growth. We were unable to disrupt both alleles of the Candida albicans RNA triphosphatase gene CaCET1, implying that the RNA triphosphatase enzyme is also essential for growth of C. albicans, a human fungal pathogen. CONCLUSIONS: Our results provide the first genetic evidence that cap synthesis is essential for growth of an organism other than Saccharomyces cerevisiae and they validate RNA triphosphatase as a target for antifungal drug discovery.

Acid Anhydride Hydrolases↗
PubMed2001

The length, phosphorylation state, and primary structure of the RNA polymerase II carboxyl-terminal domain dictate interactions with mRNA capping enzymes.

The carboxyl-terminal domain (CTD) of elongating RNA polymerase II serves as a landing pad for macromolecular assemblies that regulate mRNA synthesis and processing. The capping apparatus is the first of the assemblies to act on the nascent pre-mRNA and the one for which binding of the catalytic components is most clearly dependent on CTD phosphorylation. The present study highlights a distinctive strategy of cap targeting in fission yeast whereby the triphosphatase (Pct1) and guanylyltransferase (Pce1) enzymes of the capping apparatus do not interact physically with each other (as they do in budding yeast and metazoans), but instead bind independently to the phosphorylated CTD. In vivo interactions of Pct1 and Pce1 with the CTD in a two-hybrid assay require 12 and 14 tandem repeats of the CTD heptapeptide, respectively. Pct1 and Pce1 bind in vitro to synthetic CTD peptides containing phosphoserine uniquely at position 5 or doubly at positions 2 and 5 of each of four tandem YSPTSPS repeats, but they bind weakly (Pce1) or not at all (Pct1) to a peptide containing phosphoserine at position 2. These results illustrate how remodeling of the CTD phosphorylation array might influence the recruitment and dissociation of the capping enzymes during elongation. But how does the CTD structure itself dictate interactions with the RNA processing enzymes independent of the phosphorylation state? Using CTD-Ser5 phosphopeptides containing alanine substitutions at other positions of the heptad, we define essential roles for Tyr-1 and Pro-3 (but not Thr-4 or Pro-6) in the binding of Schizosaccharomyces pombe guanylyltransferase. Tyr-1 is also essential for binding and allosteric activation of mammalian guanylyltransferase by CTD Ser5-PO4, whereas alanine mutations of Pro-3 and Pro-6 reduce the affinity for the allosteric CTD-binding site. These are the first structure-activity relationships deduced for an effector function of the phosphorylated CTD.

Alanine↗
PubMed2001

PEGylated PLGA nanoparticles as protein carriers: synthesis, preparation and biodistribution in rats.

The aim of the present work was to assess the merits of PEGylated poly(lactic-co-glycolic acid) (PEG-PLGA) nanoparticles as protein and peptide drugs (PPD) carriers. PEG-PLGA copolymer, which could be used to prepare the stealth nanoparticles or long-circulating nanoparticles, was synthesized with methoxypolyethyleneglycol (MePEG) and PLGA. The structure of PEG-PLGA was confirmed with (1)H NMR and Fourier transform infrared (FTIR) spectrum, and molecular weight was determined by gel permeation chromatography (GPC). Bovine serum albumin (BSA), chosen as model protein, was encapsulated within the stealth nanoparticles with the double emulsion method. The particles were characterized in terms of size, zeta potential and in vitro release of the protein. The biological fate of the BSA-loaded nanoparticles following intravenous administration was determined over 24 h in rats. The experimental results showed that PEG-PLGA could be obtained by ring-opening polymerization of lactide and glycolide in the presence of MePEG. (1)H NMR and FTIR spectrum were consistent with the structure of PEG-PLGA copolymer. Molecular weight determined by GPC was 50800. The stealth nanoparticles loading BSA could be prepared by the double emulsion technique. The entrapment efficiency was 48.6%, particle size about 200 nm and zeta potential -16.1 mV. BSA release from the stealth nanoparticles showed an initial burst release and then sustained release. PEG-PLGA nanoparticles could extend half-life of BSA from 13.6 min of loaded in PLGA nanoparticles to 4.5 h and obviously change the protein biodistribution in rats compared with that of PLGA nanoparticles. Thus, PEG-PLGA nanoparticles could be an effective carrier for PPD delivery.

Animals↗
PubMed2001

Characterization of Schizosaccharomyces pombe RNA triphosphatase.

RNA triphosphatase catalyzes the first step in mRNA cap formation which entails the cleavage of the beta-gamma phosphoanhydride bond of triphosphate-terminated RNA to yield a diphosphate end that is then capped with GMP by RNA guanylyltransferase. Here we characterize a 303 amino acid RNA triphosphatase (Pct1p) encoded by the fission yeast SCHIZOSACCHAROMYCES: pombe. Pct1p hydrolyzes the gamma phosphate of triphosphate-terminated poly(A) in the presence of magnesium. Pct1p also hydrolyzes ATP to ADP and P(i) in the presence of manganese or cobalt (K(m) = 19 microM ATP; k(cat) = 67 s(-1)). Hydrolysis of 1 mM ATP is inhibited with increasing potency by inorganic phosphate (I(0.5) = 1 mM), pyrophosphate (I(0.5) = 0.4 mM) and tripolyphosphate (I(0.5) = 30 microM). Velocity sedimentation indicates that Pct1p is a homodimer. Pct1p is biochemically and structurally similar to the catalytic domain of Saccharomyces cerevisiae RNA triphosphatase Cet1p. Mechanistic conservation between Pct1p and Cet1p is underscored by a mutational analysis of the putative metal-binding site of Pct1p. Pct1p is functional in vivo in S.cerevisiae in lieu of Cet1p, provided that it is coexpressed with the S.pombe guanylyltransferase. Pct1p and other yeast RNA triphosphatases are completely unrelated, mechanistically and structurally, to the metazoan RNA triphosphatases, suggesting an abrupt evolutionary divergence of the capping apparatus during the transition from fungal to metazoan species.

Acid Anhydride Hydrolases↗
PubMed2001

Bilineal disease and trans-heterozygotes in autosomal dominant polycystic kidney disease.

In searching for a putative third gene for autosomal dominant polycystic kidney disease (ADPKD), we studied the genetic inheritance of a large family (NFL10) previously excluded from linkage to both the PKD1 locus and the PKD2 locus. We screened 48 members of the NFL10 pedigree, by ultrasonography, and genotyped them, with informative markers, at both the PKD1 locus and the PKD2 locus. Twenty-eight of 48 individuals assessed were affected with ADPKD. Inspection of the haplotypes of these individuals suggested the possibility of bilineal disease from independently segregating PKD1 and PKD2 mutations. Using single-stranded conformational analysis, we screened for and found a PKD2 mutation (i.e., 2152delA; L736X) in 12 affected pedigree members. Additionally, when the disease status of these individuals was coded as "unknown" in linkage analysis, we also found, with markers at the PKD1 locus, significant LOD scores (i.e., >3.0). These findings strongly support the presence of a PKD1 mutation in 15 other affected pedigree members, who lack the PKD2 mutation. Two additional affected individuals had trans-heterozygous mutations involving both genes, and they had renal disease that was more severe than that in affected individuals who had either mutation alone. This is the first documentation of bilineal disease in ADPKD. In humans, trans-heterozygous mutations involving both PKD1 and PKD2 are not necessarily embryonically lethal. However, the disease associated with the presence of both mutations appears to be more severe than the disease associated with either mutation alone. The presence of bilineal disease as a confounder needs to be considered seriously in the search for the elusive PKD3 locus.

Amino Acid Sequence↗
PubMed2001

Changes of urinary steroid conjugates and gonadotropin excretion in the menstrual cycle and pregnancy in the Yunnan snub-nosed monkey (Rhinopithecus bieti).

The Yunnan snub-nosed monkey (Rhinopithecus bieti) is one of the most endangered species in the world, and it is endemic to China. According to our knowledge, there was no information on reproduction for this species. The present study was designed to understand the characteristics of reproductive hormone secretion during the menstrual cycle and pregnancy of this species by monitoring urinary estrone conjugate (E1C), pregnanediol-3-glucuronide (PdG), bioactive follicle-stimulating hormone (FSH), and luteinizing hormone (LH). The urine samples were collected each day from four adult females for eight menstrual cycles, and once in 3 days during pregnancy (three full-term pregnancies, one mid-term abortion). The steroid conjugate was tested by radioimmunoassays (RIAs), and bioactive FSH and LH levels were measured in vitro by the sensitive bioassays granulosa cell aromatize bioassay (GAB) and rat interstitial cell testosterone (RICT), respectively. The results showed that: 1) E1C presented a preovulatory peak (183.9 +/- 8.6 ng/mgCr) followed by a definite elevation of PdG; 2) PdG in the luteal phase (754.4 +/- 30.6 ng/mgCr) was three- to fivefold higher than during the corresponding follicular phase (198.3 +/- 11.4 ng/mgCr); 3) the peaks of bio-LH and bio-FSH were on the same day, while the E1C peak was 1 or 2 days before the peaks for these two hormones; 4) bio-FSH levels were higher in the follicular phase than in the luteal phase, and bio-LH levels elevated slightly in the luteal phase; 5) the mean cycle length was 23.6 +/- 3.5 days (n = 3) based upon successive urinary LH peaks; 6) based on the interval from the day of E1C peak to the day of parturition, the gestation was 203.7 +/- 2.5 days (n = 3); and 7) both E1C and PdG increased and remained high after pregnancy, with a sharp decrease in basal levels following parturition or mid-term abortion. The results suggested that the pattern of reproductive hormones for R. bieti is similar to that of other Old World monkeys, but the concentration of the hormones is different from that of other species. This species has a longer progestation period, which may be related to its classification status.

Animals↗
PubMed2001

A "two-hit" model of cystogenesis in autosomal dominant polycystic kidney disease?

An intriguing feature of autosomal dominant polycystic kidney disease (ADPKD) is the focal and sporadic nature of individual cyst formation. Typically, only a few renal cysts are detectable in an affected individual during the first two decades of life. By the fifth decade, however, hundreds to thousands of renal cysts can be found in most patients. Additionally, significant intra-familial variability of ADPKD has been well documented. Taken together, these findings suggest that factor(s) in addition to the germline mutation of a polycystic kidney disease gene might be required for individual cyst formation. Indeed, recent studies have provided compelling evidence in support of a "two-hit" model of cystogenesis in ADPKD. In this model, inactivation of both copies of a polycystic kidney disease gene by germline and somatic mutations within an epithelial cell provides growth advantages for it to proliferate clonally into a cyst. This article highlights key findings of these recent studies and discusses the controversies and implications of the "two-hit" model in ADPKD.

Animals↗
PubMed2001

Prevalence of hepatitis E virus antibodies in Canadian swine herds and identification of a novel variant of swine hepatitis E virus.

Swine hepatitis E virus is a newly identified potentially zoonotic virus from pigs of particular concern for possible direct transmission to a human xenotransplant recipient by organ transplantation. In the present study, prevalence of serum antibodies to hepatitis E virus was examined in Canadian swine herds. A total of 998 serum samples collected from 6-month-old healthy slaughter hogs were examined by enzyme immunoassay and Western blot analysis for antibodies to the recombinant open reading frame 3 (ORF3) protein of hepatitis E virus expressed in Escherichia coli. These samples represented more than 80 different swine production units from five major swine-producing provinces across Canada. From this study, 594 samples (59.4%) were found to be positive for hepatitis E virus antibody. The seroprevalence was higher in Quebec (88.8%) and Ontario (80.1%) than in Alberta and Saskatchewan (38.3%). By PCR using a pair of oligonucleotide primers deduced from the ORF2 sequence of human hepatitis E virus, a specific hepatitis E virus sequence was recovered from feces of pigs. The nucleotide sequence identity between the U.S. swine hepatitis E virus and the Canadian isolate (SK3) was only 85.8%, suggesting that genotypic variations may exist in swine hepatitis E virus in North America. Among 165 serum samples collected from humans in Saskatchewan, 2.4% were found to be positive for antibodies to the hepatitis E virus ORF3 protein. Our data indicate that hepatitis E virus is highly prevalent in commercial swine populations in Canada and support the suggestion that the swine hepatitis E virus may be an important zoonotic agent for humans.

Animals↗
PubMed2001

Optical tomographic imaging of dynamic features of dense-scattering media.

Methods used in optical tomography have thus far proven to produce images of complex target media (e.g., tissue) having, at best, relatively modest spatial resolution. This presents a challenge in differentiating artifact from true features. Further complicating such efforts is the expectation that the optical properties of tissue for any individual are largely unknown and are likely to be quite variable due to the occurrence of natural vascular rhythms whose amplitudes are sensitive to a host of autonomic stimuli that are easily induced. We recognize, however, that rather than frustrating efforts to validate the accuracy of image features, the time-varying properties of the vasculature can be exploited to aid in such efforts, owing to the known structure-dependent frequency response of the vasculature and to the fact that hemoglobin is a principal contrast feature of the vasculature at near-infrared wavelengths. To accomplish this, it is necessary to generate a time series of image data. In this report we have tested the hypothesis that through analysis of time-series data, independent contrast features can be derived that serve to validate, at least qualitatively, the accuracy of imaging data, in effect establishing a self-referencing scheme. A significant finding is the observation that analysis of such data can produce high-contrast images that reveal features that are mainly obscured in individual image frames or in time-averaged image data. Given the central role of hemoglobin in tissue function, this finding suggests that a wealth of new features associated with vascular dynamics can be identified from the analysis of time-series image data.

Blood Vessels↗
PubMed2001

[An AFLP marker related to fibrogenesis in upland cotton (Gossypium hirsuturm L.)].

By using AFLP technique polymorphism analysis was performed between a fuzzlesslintless mutant line and its isogenic wild-type line, Xuzhou 142. Out of 6,360 bands produced by 64 pairs primers, a fragment, named as CF1, appearing stably in wild-type line, Xuzhou 142. This polymorphism was further verified using several normal fiber varieties and F2, F3 populations from the cross of fuzzless-lintless mutant line with a high-lint-percentage variety Yumian No. 1. The cosegregation of CF1 and fibrogenesis was proved, which suggested that CF1 can be used as a molecular marker for cotton fibrogenesis. The CF1 segment was cloned into PUCm-T Vector and then sequenced. The putative amino acid sequences, is an analogue to phenol hydroxylase alpha subunit, outer surface protein C, NADH dehydrogenase subunit 1, NADH-ubiquinone oxidoreductase, 2-oxoacid ferredoxin oxidoreduct and hypothetical 14.5kD protein.

Base Sequence↗
PubMed2001

[The cloning of apple ferritin gene (Apfl) from Malus xiaojinensis Cheng et Jiang and its structure analysis].

The special primers were designed based on the sequence information of plant ferritin genes reported in the literature and used for polymerase chain reaction (PCR) with the genomic DNA of Malus xiaojinensis Cheng et Jiang in an attempt to clone apple ferritin gene. A single fragment of 771 bp was successfully obtained from the PCRs and cloned in this study. The sequence and homology analysis results of the fragment showed that the deduced amino acids of the fragment had a ninety-nine percent homology to that of the soybean ferritin gene reported by Lescure et al. (1991). A comparison in details of the nucleotide sequence of the clone and that of the soybean ferritin gene showed that they consisted of the same open reading frame (ORF, 753 bp) and that the cloned fragment had complete initial and stop codes. Within the ORF no introns were found and there were no nucleotide difference in the transit peptide region (TP) of the gene, but five nucleotide mutations were found in the mature peptide region (MP), among which four were synonymous mutations.

Amino Acid Sequence↗
PubMed2001

[T cell and molecule-1 detection in cornea of fetus, neonates, children and adults].

OBJECTIVE: To study the immune state of human cornea with different ages. METHODS: The human corneas in different ages were detected by using immunohistochemical techniques for 5 types of monoclonal antibody. RESULTS: The contents of T-cell (CD(+)(3)), helper/inducer (CD(+)(4)), toxic T-cell (CD(+)(8)), macrophage (CD(+)(68)) and molecule-1 (intercellular adhesive molecule, CD(+)(54)) in the adult cornea were relatively low, mainly in the limbus but none at the corneal center. These positive cells were less in corneas of fetus, neonates and children than that in adults. CONCLUSION: In corneas of fetus, neonates and children, the T-cell, macrophage and molecule-1 were less than that of adults. Their corneas may be used as donors in corneal transplantation.

Adult↗
PubMed2000

Characterization of Candida albicans RNA triphosphatase and mutational analysis of its active site.

The RNA triphosphatase component (CaCet1p) of the mRNA capping apparatus of the pathogenic fungus Candida albicans differs mechanistically and structurally from the RNA triphosphatase of mammals. Hence, CaCet1p is an attractive antifungal target. Here we identify a C-terminal catalytic domain of CaCet1p from residue 257 to 520 and characterize a manganese-dependent and cobalt-dependent NTPase activity intrinsic to CaCet1p. The NTPase can be exploited to screen in vitro for inhibitors. The amino acids that comprise the active site of CaCet1p were identified by alanine-scanning mutagenesis, which was guided by the crystal structure of the homologous RNA triphosphatase from Saccharomyces cerevisiae (Cet1p). Thirteen residues required for the phosphohydrolase activity of CaCet1p (Glu287, Glu289, Asp363, Arg379, Lys396, Glu420, Arg441, Lys443, Arg445, Asp458, Glu472, Glu474 and Glu476) are located within the hydrophilic interior of an eight-strand beta barrel of Cet1p. Each of the eight strands contributes at least one essential amino acid. The essential CaCet1p residues include all of the side chains that coordinate manganese and sulfate (i.e., gamma phosphate) in the Cet1p product complex. These results suggest that the active site structure and catalytic mechanism are conserved among fungal RNA triphosphatases.

Acid Anhydride Hydrolases↗