bluuebunny/crossref_metadata_2025 huggingface dataset:
Developmental changes in hepatic metallothionein, zinc, and copper levels in genetically altered mice
Authors: Lau John C , Cherian M George
Published: April 2011

Using mice that either overexpress metallothionein 1 (MT-1*) or do not express metallothionein 1 and 2 (MT-null) and a control strain (C57BL/6), the essential metal storage function of hepatic metallothionein and its subcellular localization were investigated during development. Hepatic metallothionein, zinc, and copper levels were measured in all groups from gestational day 20 to 60 days of age. Hepatic metallothionein levels were maximal during the perinatal period in both MT-1* and C57BL/6 mice with levels approximately three times higher in MT-1* mice. MT-null mice had no detectable hepatic metallothionein throughout development. Hepatic zinc levels were highest in the neonatal period of MT-1* and C57BL/6 mice and declined to adult levels by 30 days of age, while hepatic zinc levels in MT-null mice did not vary markedly throughout development. Hepatic copper profiles were very similar in MT-1* and MT-null mice as compared with the C57BL/6 mice. Correlation analysis showed a strong positive correlation between hepatic metallothionein and zinc levels in MT-1* mice, moderate correlation between hepatic metallothionein and metals in C57BL/6 mice, but only a very weak correlation between hepatic metallothionein and copper levels in MT-1* mice. Immunohistochemical localization showed specific nuclear staining in both MT-1* and C57BL/6 mice during the neonatal period with a gradual shift to the cytoplasm. The results show that hepatic metallothionein is a major determinant of zinc but not copper levels during murine development. Additionally, hepatic metallothionein levels and localization are regulated in a similar manner in MT-1* and C57BL/6 mice. The MT-null mice maintain a basal level of zinc sufficient for development, which was found to be 15.9 mug/g. This value was similar to the levels of hepatic zinc that was not bound to metallothionein in MT-1* and C57BL/6 mice during development.Key words: metallothionein, zinc, copper, development, immunohistochemistry.
NMR spectroscopic and enzymatic studies of DNA hairpins containing mismatches in the EcoRI recognition site
Authors: Germann Markus W , Kalisch Bernd W , Varnum James M , Vogel Hans J , van de Sande Johan H
Published: April 2011

We have correlated the structural perturbations caused by DNA mismatches with the enzymatic data of the interaction of the restriction endonuclease EcoRI with DNA. Oligonucleotides d(CGAGAATTCTCA5GAXAATTCT) (X = G, A, T) and d(CGCGAATTYGCGT4CGCXAATTCGCG) (Y = C, X = G, T and Y = A, X = T) containing single mismatches within the EcoRI recognition site were characterized by NMR spectroscopy and by their EcoRI substrate properties. UV melting and gel electrophoresis studies confirm that the oligonucleotides form hairpin structures. The presence of either a CT or a CA mismatch results in markedly lower Tm and van't Hoff enthalpies compared with the fully base paired control. NMR imino proton spectra of these hairpins demonstrate that the perturbation caused by the two mispairs or a noncanonical AT pair is localized and limited to one or two base pairs on either side of the perturbation. The DNA hairpin structures containing single mismatches, and to a lesser extent also sequences with a single noncanonical base pair, are substrates for the restriction endonuclease. In addition to the strand scission at the nonperturbed GpA phosphodiester bond some cleavage is observed at the mismatched position. The interactions of the CA and CT mismatched hairpin with the enzyme are characterized by binding constants that are only 33 and 57 times lower, respectively, than that for the canonical sequence, corresponding to 8-10 kJ·mol-1 less favorable free binding energy. This, taken together with the NMR data, indicates that the CA and CT mismatches have only small effects on the EcoRI recognition of the DNA substrate. We conclude that two out of the three hydrogen bonds that characterize the interaction of EcoRI with the CG base pair in the canonical sequence can still be formed for either the CT or CA mismatched recognition site.Key words: DNA hairpins, EcoRI recognition, mismatches, imino protons.
Theoretical calculations of acid-dissociation constants of proteins
Authors: Juffer André H
Published: April 2011

The purpose of this review is to introduce several computational procedures for the determination of acid-dissociation constants (pKa) of titratable groups in proteins. Several concepts, such as continuum electrostatics and the exact meaning of intrinsic and apparent pKas, will be explained in some detail. Each of the methods will be judged on its merits, and some comparisons between the methods will be presented. While the emphasis of this review will be on theoretical formulations, the experimental determination by means of nuclear magnetic resonance will be briefly explained. The determination of individual pKa values by nuclear magnetic resonance in combination with computationally determined pKas can provide unique information about the pH-dependent properties of proteins and their complexes with peptides, DNA, and ligands.Key words: acid-dissociation constants, NMR, continuum electrostatics, dielectric constant of proteins, Monte Carlo, molecular dynamics.
Protein chemical shift analysis: a practical guide
Authors: Wishart David S , Nip Alex M
Published: April 2011

Proper protein chemical shift analysis requires careful experimental measurements and the implementation of standardized referencing procedures. In this article we outline the steps necessary to ensure proper chemical shift referencing and the selection criteria for choosing appropriate "random coil" amino acid chemical shift values for predicting, comparing, and assigning 1H, 13C, and 15N resonances in proteins. By making use of these standardized conditions we demonstrate how several recently developed methods, namely homologous assignment techniques and empirical chemical shift contour maps (or hypersurfaces), can significantly improve the accuracy of chemical shift prediction for 1H, 13C, and 15N nuclei. In addition to illustrating the potential utility of chemical shift prediction, we also outline procedures for identifying secondary structure elements through heteronuclear chemical shift analysis and further demonstrate how empirical shift contour maps can actually be used to refine, and more importantly generate, reasonably good three-dimensional protein structures.Key words: NMR, chemical shift, prediction, structure, protein.
The effect of dietary flaxseed supplementation on organic anion and osmolyte content and excretion in rat polycystic kidney disease
Authors: Ogborn Malcolm R , Nitschmann Evan , Bankovic-Calic Neda , Buist Richard , Peeling James
Published: April 2011

Progression of chronic renal failure in the Han:SPRD-cy rat polycystic kidney disease is associated with renal depletion of citric acid cycle metabolites and betaine. Amelioration of this disease by a soy protein diet is associated with retention of citric acid cycle anions, despite increased excretion, and preservation of tissue levels of betaine. As we have recently found that modest dietary supplementation with flaxseed preserves renal function and reduces histologic injury in the Han:SPRD-cy rat, we undertook a high-resolution 1H NMR spectroscopic study of urine and renal tissue extracts from Han:SPRD-cy rats to explore the renal biochemical consequences of a flaxseed diet. There was no significant dietary effect upon organic anion, methylamine, or osmolyte excretion in healthy animals. There was increased citrate excretion in Han:SPRD-cy rats fed flaxseed. Urinary ammonium excretion did not differ, suggesting that the observed increase in citrate excretion was not due to an alkaline effect of diet. Tissue extract studies revealed that disease amelioration was associated with tissue retention of succinate and betaine. Amelioration of Han:SPRD-cy rat polycystic kidney disease by diet is associated with alteration in the handling of citric acid cycle metabolites. Betaine may have a metabolic role in the reduction of chronic renal injury.Key words: 1H NMR spectroscopy, polycystic kidney disease, rat, flaxseed.
NMR for the design of functional mimetics of protein-protein interactions: one key is in the building of bridges
Authors: Song Jianxing , Ni Feng
Published: April 2011

Using the design of bivalent and bridge-binding inhibitors of thrombin as an example, we review an NMR-based experimental approach for the design of functional mimetics of protein-protein interactions. The strategy includes: (i) identification of binding residues in peptide ligands by differential resonance perturbation, (ii) determination of protein-bound structures of peptide ligands by use of transferred NOEs, (iii) minimization of larger protein and peptide ligands on the basis of NMR structural information, and (iv) linkage of two weakly binding mimetics to produce an inhibitor with enhanced affinity and specificity. This approach can be especially effective for the design of potent and selective functional mimetics of protein-protein interactions because it is less likely that the surfaces of two related proteins or enzymes share two identical binding sites or regions.Key words: NMR, protein-protein interactions, functional mimetics, bridge-binding inhibitors, thrombin.
Solid-state NMR studies of magnetically aligned phospholipid membranes: taming lanthanides for membrane protein studies
Authors: Prosser R Scott , Volkov V B , Shiyanovskaya I V
Published: April 2011

The addition of lanthanides (Tm3+, Yb3+, Er3+, or Eu3+) to a solution of long-chain phospholipids such as dimyristoylphosphatidylcholine (DMPC) and short-chain phospholipids such as dihexanoylphosphatidylcholine (DHPC) is known to result in a bilayer phase in which the average bilayer normal aligns parallel to an applied magnetic field. Lanthanide-doped bilayers have enormous potential for the study of membrane proteins by solid-state NMR, low-angle diffraction, and a variety of optical spectroscopic techniques. However, the addition of lanthanides poses certain challenges to the NMR spectroscopist: coexistence of an isotropic phase and hysteresis effects, direct binding of the paramagnetic ion to the peptide or protein of interest, and severe paramagnetic shifts and line broadening. Lower water concentrations and larger DMPC/DHPC ratios than those typically used in bicelles consistently yield a single oriented bilayer phase that is stable over a wide range of temperature (~35-90°C). Among the above choice of lanthanides, Yb3+ is found to give minimal paramagnetic shifts and line broadening at acceptably low concentrations necessary for alignment (i.e., Yb3+/DMPC mole ratios equal to or greater than 0.01). Finally, the addition of a phospholipid chelate, 1,2-dimyristoyl-sn-glycero-3-phosphoethanolamine - diethylenetriaminepentaacetic acid, is observed to significantly reduce paramagnetic broadening and presumably prevent direct association of the peptide with the lanthanide ions.Key words: lanthanide, solid-state NMR, model membrane, membrane protein structure.
New perceptions of transcription factor properties from NMR
Authors: Bagby Stefan , Arrowsmith Cheryl H , Ikura Mitsuhiko
Published: April 2011

The complementarity of NMR and X-ray crystallography for biomacromolecular studies has been particularly evident in analysis of transcription factor structures and interactions. While X-ray crystallography can be used to tackle relatively complicated structural problems including multicomponent (three and higher) complexes, NMR studies have provided new insights into the nature of protein-DNA and protein-protein interactions that would be difficult to obtain by other biophysical methods. We describe herein some of the novel and important information recently derived from NMR studies of transcription factors.Key words: protein-DNA interaction, protein-protein interaction, induced folding, conformational fluctuations, transcriptional regulation.
Comparative study of free and bound glycolytic enzymes from sea scorpion brain
Authors: Lushchak Volodymyr I , Lushchak Ljudmyla P , Bahnjukova Tetjana V , Spichenkov Alexei V , Storey Kenneth B
Published: April 2011

Free and bound forms of hexokinase, pyruvate kinase, and lactate dehydrogenase were prepared from the brain of the sea scorpion (Scorpaena porcus) in a low ionic strength medium. Properties of the free and bound forms were compared to determine whether binding to particulate matter could influence enzyme function or stability in vivo. Changes in pH differently affected the activity of the free and bound forms of all three enzymes. Furthermore, bound forms of hexokinase and pyruvate kinase were more stable than the free enzymes to heating at 45°C. Bound hexokinase showed higher affinity for substrates (ATP, glucose) than the free form and bound lactate dehydrogenase had greater affinity for pyruvate and NADH. Although the affinities of the two forms of pyruvate kinase for substrates were similar, Hill coefficients for phosphoenolpyruvate as well as inhibition by ATP differed between the two enzyme forms. Free and bound lactate dehydrogenase also showed differences in Hill coefficients and bound lactate dehydrogenase was less sensitive to substrate inhibition by high pyruvate concentrations. The possible physiological role of the binding of these glycolytic enzymes to subcellular structures is discussed.Key words: hexokinase, lactate dehydrogenase, pyruvate kinase, enzyme binding, Scorpaena porcus.
A bioactive peptide from the transmembrane 5 - intracellular loop 3 region of the human 5HT1a receptor
Authors: Hayataka Kenneth , O'Connor Mary-Frances , Kinzler Nancy , Weber John T , Parker Keith K
Published: April 2011

15 amino acid peptide from the transmembrane 5 - intracellular loop 3 region of the human 5HT1a receptor produced concentration-dependent decreases in agonist binding. This result is consistent with a competitive interaction between peptide, receptor, and G protein at the receptor - G protein interface. Bombesin and a 13 amino acid peptide from the carboxyl terminus region of the receptor were inactive. Additionally, the peptide decreased forskolin-mediated cAMP elevation. Overall, these results suggest that amino acid residues from this region of the receptor are involved in receptor - G protein coupling and that G protein is activated by the receptor.Key words: serotonin, 5HT1a receptor, G protein, cAMP, loop peptide.
Effect of peptide binding on amide proton exchange rates in the PDZ2 domain from human phosphatase hPTP1E
Authors: Ekiel Irena , Banville Denis , Shen Shi Hsiang , Gehring Kalle
Published: April 2011

Amide hydrogen-deuterium exchange rates were measured in the PDZ2 domain from human phosphatase hPTP1E by 1H-15N heteronuclear NMR spectroscopy. Protection factors were calculated for the slowly exchanging hydrogens in both the free PDZ2 domain and its complex with an octapeptide peptide, R-N-E-I-Q-S-L-V, derived from the C-terminus of the Fas receptor. Aside from a short α-helical region α1 (amino acids A-45 to D-49), the pattern of highly protected amides correlated well with the presence of hydrogen bonds in elements of the secondary structure. Hydrogen-bonded amides showed relatively fast exchange rates with half-lives of less than 9 h at pD 7.6 and 8°C. Protection factors, calculated as the ratio of theoretical (denatured) and observed exchange rates, showed less dispersion in maximal values than did the actual exchange rates. This behavior and the large pH dependence of the exchange rates suggest that amide exchange is close to the EX2 limit. In this limit, exchange of the most protected amides occurs through a global unfolding mechanism. The free energy of the unfolding calculated from the largest protection factors is 4.8 ± 0.4 kcal/mol (1 cal = 4.184 J). This ΔG° closely matches the value measured by experiments with guanidine hydrochloride and fluorescence emission spectroscopy. Peptide binding to PDZ2 resulted in mostly global effects and stabilized the folded domain by 1.4 kcal/mol.Key words: PDZ2 from hPTP1E, amide exchange, ligand binding, NMR.
Stable expression of a recombinant sodium-dependent, pyrimidine-selective nucleoside transporter (CNT1) in a transport-deficient mouse leukemia cell line
Authors: Crawford Charles R , Cass Carol E , Young James D , Belt Judith A
Published: April 2011

Previous studies of nucleoside transport in mammalian cells have identified two types of activities: the equilibrative nucleoside transporters and concentrative, Na+-nucleoside cotransporters. Characterization of the concentrative nucleoside transporters has been hampered by the presence in most cells and tissues of multiple transporters with overlapping permeant specificities. With the recent cloning of cDNAs encoding rat and human members of the concentrative nucleoside transporter (CNT) family, it is now possible to study the concentrative transporters in isolation by use of functional expression systems. We report here the isolation of a nucleoside transport-deficient subline of L1210 mouse leukemia (L1210/DNC3) that is a suitable recipient for stable expression of cloned nucleoside transporter cDNAs. We have used L1210/DNC3 as the recipient in gene transfer studies to develop a stable cell line (L1210/DU5) that produces the recombinant concentrative nucleoside transporter with selectivity for pyrimidine nucleosides (CNT1) that was initially identified in rat intestine (Q.Q. Huang, S.Y. Yao, M.W. Ritzel, A.R.P. Paterson, C.E. Cass, and J.D. Young. 1994. J. Biol. Chem. 269: 17 757 - 17 760). L1210/DU5 was used to examine the permeant selectivity of recombinant rat CNT1 by comparing a series of nucleoside analogs with respect to (i) inhibition of inward fluxes of [3H]thymidine, (ii) initial rates of transport of 3H-analog, and (iii) cytotoxicity to L1210/DU5 versus the parental transport-deficient cell line. By all three criteria, recombinant CNT1 transported 5-fluoro-2prime-deoxyuridine and 5-fluorouridine well and cytosine arabinoside poorly. Although some purine nucleosides (2prime-deoxyadenosine, 2-chloro-2prime-deoxyadenosine, 7-deazaadenosine) were potent inhibitors of CNT1, they were poor permeants when uptake was measured directly by analysis of isotopic fluxes or indirectly by comparison of cytotoxicity ratios. We conclude that comparison of analog cytotoxicity to L1210/DU5 versus L1210/DNC3 is a reliable indirect predictor of transportability, suggesting that cytotoxicity assays with a panel of such cell lines, each with a different recombinant nucleoside transporter, would be a valuable tool in the development of antiviral and antitumor nucleoside analogs.Key words: nucleoside transporter, CNT1, rat, sodium-dependent, recombinant, cloned gene, transfection, stable transfectant.
Epidermal cell lineage
Authors: Turksen Kursad , Troy Tammy-Claire
Published: April 2011

The epidermis is a stratified squamous epithelium, which is under a constant state of proliferation, commitment, differentiation, and elimination so that the functional integrity of the tissue is maintained. The intact epidermis has the ability to respond to diverse environmental stimuli by continuous turnover to maintain its normal homeostasis throughout an organism's life. This is achieved by a tightly regulated balance between stem cell self-renewal and the generation of a population of cells that undergo a limited number of more rapid (amplifying) transit divisions before giving rise to nonproliferative, terminally differentiating cells. This process makes it an excellent model system to study lineage, commitment, and differentiation, although neither the identity of epidermal stem cells nor the precise steps and regulators that lead to mature epidermal cells have yet been determined. Furthermore, the identities of genes that initiate epidermal progenitor commitment to the epidermal lineage, from putative epidermal stem cells, are unknown. This is mainly due to the lack of an in vitro model system, as well as the lack of specific reagents, to study the early events in epidermal lineage. Our recent development of a differentiating embryonic stem cell model for epidermal lineage now offers the opportunity to analyze the factors that regulate epidermal lineage. These studies will provide new insight into epidermal lineage and lead to a better understanding of various hyperproliferative skin diseases such as psoriasis and cancer.Key words: epidermis, lineage differentiation, embryonic stem cells.
Commitment and differentiation of stem cells to the osteoclast lineage
Authors: Hayashi Shin-Ichi , Yamane Toshiyuki , Miyamoto Akitomo , Hemmi Hiroaki , Tagaya Hisashi , Tanio Yasuko , Kanda Hidenobu , Yamazaki Hidetoshi , Kunisada Takahiro
Published: April 2011

Osteoclasts are hematopoietic cells which play important roles in bone remodeling and resorption. They have phenotypic characteristics of the monocyte/macrophage lineages. In this review we first describe the phylogeny of osteoclasts. Osteoclast generation is closely linked to the presence of bone tissues. The formation of bone cavities in aquatic animals is underdeveloped, even though they have cells which have the potential to differentiate into osteoclasts. Next we describe recent advances in our understanding of osteoclastogenesis that have resulted from the identification of critical molecules and mutated genes of osteopetrotic mice. Reports that transcriptional factors PU.1 and c-Fos are essential for commitment and (or) differentiation into the osteoclast lineage and novel culture systems, which have clarified some characteristics of osteoclast precursors, are also described. We are now able to induce mature osteoclasts from hematopoietic stem cells and even from totipotent embryonic stem cells. Cell lines that differentiate into osteoclasts are also available. Using these culture systems and cell lines, the interactions of osteoclasts with osteoblastic stromal cells, which produce critical molecules for osteoclastogenesis, have been studied. Very recently, one of these critical molecules, osteoclast differentiation factor / osteoprotegerin-ligand, was cloned. The presence of this factor and macrophage-colony-stimulating factor is sufficient to induce osteoclast development in cultures inoculated only with an osteoclast precursor cell line. We review the present status and the remaining questions in osteoclast biology.Key words: osteoclast, stem cell, osteopetrosis, M-CSF, ODF/OPGL, hematopoiesis.
Alpha-periodicity analysis of small multidrug resistance (SMR) efflux transporters
Authors: Edwards Robert A , Turner Raymond J
Published: April 2011

Proteins in the small multidrug resistance (SMR) family of transport proteins are about 110 amino acids in length and are predicted to have four transmembrane helices. This family is divided into a two groups, one of which we have referred to as small multidrug pumps (Smp) and confer resistance to a wide variety of quaternary ammonium compounds through a proton-drug efflux antiport mechanism. Members of the second group within this family have, as yet, not had their substrate profile characterized and are referred to as Sug proteins. Alpha-periodicity analysis was conducted on a set of six homologous proteins of the SMR family consisting of three established Smp and three Sug proteins. Several amino acid properties were used in the analysis including hydropathy, variability, and a substitution matrix for lipid exposed amino acids. The scanning window was varied between 8 and 14 residues and the alpha-periodicity was calculated from the peaks in the Fourier transform power spectra in the region between 3.0 and 4.3 residues/turn. This analysis adds to the hydropathy analysis to give a more confident prediction of which residues are within the lipid bilayer for each of the four transmembrane helices. Information was also obtained that allowed for the identification of zones within each transmembrane helix that face the interior of the helical bundle on one side and are lipid exposed on the other face.Key words: modeling, SMR, QAC, multidrug resistance, transporter, hydrophopathy, periodicity, amphipathicity.
Inhibition of P-glycoprotein by cyclosporin A analogues and metabolites
Authors: Demeule Michel , Laplante Alain , Sepehr-Araé Arash , Beaulieu Édith , Averill-Bates Diana , Wenger Roland M , Béliveau Richard
Published: April 2011

The interaction between P-glycoprotein (P-gp) from membranes isolated from multidrug-resistant Chinese hamster ovary cells and cyclosporin A (CsA) analogues and its metabolites was characterized. Screening of these latter as chemosensitizers was performed using three different assays: (i) vinblastine uptake, (ii) photoaffinity labeling by [125I]iodoaryl azidoprazosin, and (iii) P-gp ATPase activity. Oxidation of the hydroxyl group at position 1 of CsA (200-096), CsG (215-834), or CsD (PSC-833) increased their inhibition of P-gp. CsA analogues (208-032, 208-183) modified at position 11 retained their ability to inhibit P-gp while analogues modified at position 2 (CsC and CsD) lost their efficiency. The inhibitions induced by metabolites of CsA were also compared to those obtained with CsG metabolites. From all the molecules tested, PSC-833 and 280-446 peptolide were the strongest inhibitors. Our results indicate that modifications of CsA analogues at position 1 and 2 are critical for their interaction with P-gp and that CsA metabolites retain a portion of the inhibitory activity of the parent drug.Key words: P-glycoprotein, cyclosporin A, vinblastine uptake, photolabeling, ATPase activity.
Nitric oxide regulates interleukin-8 gene expression in activated endothelium by inhibiting NF-κB binding to DNA: effects on endothelial function
Authors: Fowler, III Alph A , Fisher Bernard J , Sweeney Lori B , Wallace Timothy J , Natarajan Ramesh , Ghosh Siddhartha S , Ghosh Shobha
Published: April 2011

Nuclear factor-kappaB (NF-κB) binds to nucleotide sequences between -80 and -70 bp upstream of the transcriptional start site in the interleukin-8 (IL-8) promoter and is crucial for transcription of the IL-8 gene. We showed that exogenous nitric oxide in the form of a nitric oxide donor significantly reduced IL-8 mRNA in cytokine-activated ECV304. Similarly, nitric oxide significantly reduced migration of polymorphonuclear neutrophils through cytokine-activated ECV304 monolayers, an IL-8-dependent process. Using a luciferase reporter construct containing the NF-κB site of the IL-8 gene, we showed that exposing cytokine-activated ECV304 to exogenous nitric oxide resulted in significant reduction of NF-κB binding. Follow-up studies using a luciferase reporter construct possessing a mutated NF-κB site confirmed that the luciferase activity observed in the NF-kappaB reporter resulted from NF-κB binding. These studies demonstrate that nitric oxide, supplied exogenously into reactions containing activated endothelium, down-regulates pro-inflammatory activity, such as the secretion of chemokines, and functional activity, such as transendothelial migration of neutrophils.Key words: interleukin-8, nuclear factor κ B, transendothelial migration, nitric oxide.
Targeting of the mammalian nucleoporin p62 to the nuclear envelope in the yeastSaccharomyces cerevisiaeand HeLa cells
Authors: Barth Werner , Chatterjee Shivani , Stochaj Ursula
Published: April 2011

We have analyzed the sorting of the mammalian nucleoporin p62 in human culture cells and in the yeast Saccharomyces cerevisiae. To this end, gene fusions were generated that carry Aequorea victoria green fluorescence protein and defined portions of p62. Upon transient gene expression fluorescent fusion proteins were localized in HeLa cells. Likewise, fusion proteins were studied in S. cerevisiae using wild-type as well as mutant cells that cluster nuclear pore complexes. Our results demonstrate that evolutionarily distant organisms, such as humans and yeasts, recognize the same sequence elements of p62 for sorting to the nuclear envelope. Specifically, the entire sequence of p62 or its complete C-terminal domain targeted fusion proteins to the nuclear membranes. In contrast, truncations of the C-terminal domain or the N-terminal segment of p62 failed to associate with the nuclear envelope in either organism. In HeLa cells overexpression of several p62-containing fusion proteins resulted in nuclear fragmentation. The C-terminal domain of p62 caused this effect, and amino acid residues 477 to 525 were sufficient to induce aberrant nuclei. Thus, overexpression of 49 amino acid residues located at the C-terminal tail of p62 interferes with the nuclear integrity in human culture cells.Key words: nuclear pore complex, nuclear transport, nucleoporin, green fluorescent protein, transfection.
Aminoacyl-tRNA synthetase genes ofBacillus subtilis: organization and regulation
Authors: Pelchat Martin , Lapointe Jacques
Published: April 2011

In Bacillus subtilis, 14 of the 24 genes encoding aminoacyl-tRNA synthetases (aaRS) are regulated by tRNA-mediated antitermination in response to starvation for their cognate aminoacid. Their transcripts have an untranslated leader mRNA of about 300 nucleotides, including alternative and mutually exclusive terminator-antiterminator structures, just upstream from the translation initiation site. Following antitermination, some of these transcripts are cleaved leaving at the 5prime-end of the mature mRNAs, stable secondary structures that can protect them against degradation. Although most B. subtilis aaRS genes are expressed as monocistronic mRNAs, the gltX gene encoding the glutamyl-tRNA synthetase is cotranscribed with cysE and cysS encoding serine acetyl-transferase and cysteinyl-tRNA synthetase, respectively. Transcription of gltX is not controlled by a tRNA, but tRNACys-mediated antitermination regulates the elongation of transcription into cysE and cysS. The full-length gltX-cysE-cysS transcript is then cleaved into a monocistronic gltX mRNA and a cysE-cysS mRNA.Key words: regulation, aminoacyl-tRNA synthetase, T-Box, processing.
Gene expression in rabbit menisci during pregnancy
Authors: Le Graverand Marie-Pierre Hellio , Reno Carol , Hart David A
Published: April 2011

Recent studies have indicated that pregnancy can affect cellular activity in connective tissues such as cartilage, ligaments, and tendons. However, the impact of pregnancy on cellular activity in the menisci, a critical component in joint function, has not been reported. Therefore,the purpose of this study was to evaluate mRNA levels for several relevant molecules in both medial and lateral menisci from the knees of first-time pregnant immature rabbits (primigravida), third-time pregnant mature rabbits (multiparous), and nonpregnant rabbits (age-matched immature and mature controls) by the sensitive molecular technique of semiquantitative reverse transcription - polymerase chain reaction. Total RNA yields from the medial meniscus of multiparous rabbits were reduced to 66% of age-matched control values; however, yields from medial and lateral menisci from primigravida animals or the lateral meniscus of multiparous animals were not significantly depressed. DNA yields were not affected by pregnancy. Type I collagen mRNA levels were significantly depressed in both menisci only in primigravida rabbits. Versican mRNA levels were significantly elevated in both menisci only in multiparous rabbits. None of the transcripts for the other matrix molecules assessed were influenced by pregnancy. Collagenase mRNA levels were unaffected by pregnancy, but TIMP-1 mRNA levels were significantly decreased in the medial meniscus of primigravida rabbits and in the lateral meniscus of multiparous rabbits. Complex changes in the pattern of mRNA expression were observed for growth factors (TGF-beta, bFGF, and IGF2). Inducible nitric oxide synthase mRNA expression was not altered during pregnancy. Transcripts for cyclooxygenase-2 were 61 and 50% of control values in the medial meniscus of primigravida and multiparous animals, respectively, while cyclooxygenase-2 mRNA levels were 150 and 188% of control values in the lateral meniscus from primigravida and multiparous animals, respectively. Such results indicate that pregnancy-induced changes in the pattern of mRNA expression are meniscus specific. Furthermore, the results support the hypothesis that different connective tissues of the knee respond to pregnancy in a unique manner.Key words: medial menisci, lateral menisci, molecular biology of menisci, pregnancy.
Identification of sds21 in fission yeast in an inhibitor-resistant high molecular mass protein phosphatase-1 complex
Authors: Dawson John F , Holmes Charles FB
Published: April 2011

While characterizing the type-1 protein phosphatases sds21 and dis2 in fission yeast (Schizosaccharomyces pombe) a novel high molecular mass protein was identified with serine/threonine phosphatase activity (referred to as PP-R) that was resistant to a panel of characteristic inhibitors of protein phosphatases. Purification of the native sds21 catalytic isoform of protein phosphatase-1 (PP-1) from an S. pombe knockout strain lacking dis2 (Δdis2) resulted predominantly in identification of PP-R. To test the hypothesis that the catalytic activity of PP-R comprised sds21, a parallel purification was performed of PP-1 activity from an S. pombe knockout strain lacking sds21 (Δsds21). Both Δsds21 and Δdis2 strains exhibited similar protein phosphatase activity profiles as determined by DEAE-sepharose, Mono-Q and Superdex gel filtration chromatography. However, the peak of protein phosphatase activity from Δsds21 S. pombe that co-migrated with PP-R from Δdis2 S. pombe exhibited the sensitivity to a panel of inhibitors that was characteristic of a type-1 protein phosphatase. These data suggest that the catalytic subunit of PP-R comprises sds21 and that the resistance to inhibitors may originate from structural differences between dis2 and sds21 isoforms. A key structural feature present in sds21, but lacking in dis2, is a classical phosphorylation consensus sequence surrounding serine-145 of sds21. The previous hypothesis was that PP-1 activity among several lower eukaryotes may be regulated directly by cAMP-dependent protein kinase (PKA) phosphorylation. However, this study demonstrated that recombinant sds21 is not a target for PKA in vitro. The constrained configuration of the putative PKA site on the PP-1 holoenzyme may restrict its ability to be targeted by PKA.Key words: cAMP-dependent protein kinase, protein phosphatase-1, sds21, dis2, G-subunit, microcystin-LR, okadaic acid, S. pombe.
Ischemia induced activation of heat shock protein 27 kinases and casein kinase 2 in the preconditioned rabbit heart
Authors: Kim Sung O , Baines Christopher P , Critz Stuart D , Pelech Steven L , Katz Sidney , Downey James M , Cohen Michael V
Published: April 2011

Protein kinase C (PKC), p38 MAP kinase, and mitogen-activated protein kinase-activated kinases 2 and 3 (MAPKAPK2 and MAPKAPK3) have been implicated in ischemic preconditioning (PC) of the heart to reduce damage following a myocardial infarct. This study examined whether extracellular signal-regulated kinase (Erk) 1, p70 ribosomal S6 kinase (p70 S6K), casein kinase 2 (CK2), and other hsp27 kinases are also activated by PC, and if they are required for protection in rabbit hearts. CK2 and hsp27 kinase activities declined during global ischemia in control hearts, whereas PC with 5 min ischemia and 10 min reperfusion increased their activities during global ischemia. Resource Q chromatography resolved two distinct peaks of hsp27 phosphotransferase activities; the first peak (at 0.36 M NaCl) appeared to correspond to the 55-kDa MAPKAPK2. Erk1 activity was elevated in both control and PC hearts after post-ischemic reperfusion, but no change was observed in p70 S6K activity. Infarct size (measured by triphenyltetrazolium staining) in isolated rabbit hearts subjected to 30 min regional ischemia and 2 h reperfusion was 31.0 ± 2.6% of the risk zone in controls and was 10.3 ± 2.2% in PC hearts (p < 0.001). Neither the CK2 inhibitor 5,6-dichloro-1-β-D-ribofuranosylbenzimidazole (DRB) nor the Mek1/2 inhibitor PD98059 infused during ischemia blocked protection by PC. The activation of CK2 and Erk1 in ischemic preconditioned hearts appear to be epiphenomena and not required for the reduction of infarction from myocardial ischemia.Key words: Erk1, MAPKAPK2, PD98059, p38 MAPK.
Superoxide generation and tyrosine kinase
Authors: Yang Su , Hardaway Martha , Sun George , Ries William L , Key Jr L Lyndon
Published: April 2011

NADPH oxidase is a multi-subunit enzyme complex responsible for superoxide generation in many cells, for example, B-lymphocytes and osteoclasts. NADPH oxidase is localized on the cell surface and generates superoxide extracellularly. After synthesis, components of this oxidase are transported to the cell membrane where the functional NADPH oxidase complex is assembled. The mechanism by which the membrane-bound components are transported to the cell surface of osteoclasts remains unclear. In this study, we examined the role of tyrosine kinase activity in the transport of NADPH oxidase components. When B-lymphocytes and osteoclasts were treated with herbimycin A, a specific inhibitor of tyrosine kinase, superoxide production was significantly decreased. The amount of p91, the catalytic subunit of NADPH oxidase, was decreased in the cellular membrane of herbimycin A treated cells compared to untreated controls. Similar results were obtained for the movement of a regulatory subunit of the NADPH oxidase complex, p47, in B-lymphocytes. Thus, inhibition of tyrosine kinase decreases superoxide production by disrupting the translocation of the NADPH oxidase complex.
THE SCATTERING LENGTHS OF THE DEUTERON
Authors: Hurst D. G. , Alcock N. Z.
Published: April 2011

The angular variation of the scattering of neutrons of 0.0724 ev. energy by deuterium gas has been measured. Comparison with theoretical calculations of this variation gives a ratio of scattering lengths:[Formula: see text]In combination with the known total scattering cross section of the free deuteron of 3.44 ± 0.06 barns this gives for the scattering lengths the two sets of values:[Formula: see text]
UPPER AND LOWER BOUNDS FOR THE ASYMPTOTIC NEUTRON DENSITY IN MILNE'S PROBLEM FOR THE SPHERE
Authors: Seidel W. , Marshak R. E.
Published: April 2011

Rigorous upper and lower bounds for the asymptotic neutron density in Milne's problem for the sphere are calculated by means of an extension of Hopf's method for the plane.
ABNORMAL E REGION IONIZATION
Authors: Gerson N. C.
Published: April 2011

Oblique incidence radio observations on sporadic E reveal both the movement and geographical extent of these reflection areas. On 13 June 1949 two Es centers were observed by this method. The first sporadic E center developed rapidly until it included an area of over 106 km.2; the second Es center was much smaller. The velocity of the center of mass of the first area was about SE 100 km. per hr. (in the meteorological usage; i.e., from the SE) and the velocity of the second, about SSE 270 km. per hr. Drift velocities in the ionosphere obtained by other investigators are of about this order of magnitude.
THE EMISSION OF RADIOACTIVE NUCLEI IN COSMIC RAY STARS
Authors: Pickup E. , Voyvodic L.
Published: April 2011

It has been found that a certain proportion of the fragments emitted in cosmic ray stars formed at about 85,000 ft. consists of radioactive nuclei, i.e., in electron sensitive photographic emulsions, tracks of electrons with energies of several mega electron volts can be seen originating at the end of the track of the fragment. Details of such events are given, together with energy measurements for the disintegration electrons made by the multiple Coulomb scattering method. The significance of the results, and possible identification of the fragments, are discussed.
SPECTRUM AND STRUCTURE OF THE BORON MONOSULPHIDE (BS) MOLECULE
Authors: Zeeman P. B.
Published: April 2011

Two band systems of the BS molecule, called the α and γ systems, have been excited in a discharge through B2S3 vapor in a quartz discharge tube. Vibrational and rotational analyses of these systems have been carried out, and it is shown that both systems have the same lower state, which is a 2Σ state. Both the upper states are 2Π states. The α system is analogous to the α system of BO, but the γ system has not been observed for BO. Tables giving the vibrational and rotational constants of the various states are given. A third system of strong bands in the blue–green region is observed simultaneously with the α and γ bands in the discharge. These bands have not yet been interpreted. By means of the observed isotopic bands, it has been proved that BS is the emitter of the α and γ systems.
THE EFFECT OF ION BOMBARDMENT ON THE EMISSION FROM OXIDE COATED CATHODES
Authors: Redhead P. A.
Published: April 2011

Some preliminary measurements of the decay of emission caused by ion bombardment of oxide coated cathodes are presented. It is shown that cathode life increases with emission density if ion bombardment is prevented.
VARIATION OF METEOR ECHO RATES WITH RADAR SYSTEM PARAMETERS
Authors: McKinley D. W. R.
Published: April 2011

Observations made with crossed-polarization radar system systems do not support the suggestion that the ionized meteor trail may act as a strong filter–polarizer of the incident radio wave. Experiments have been carried out to determine the variation of normal meteor echo rates with transmitter power, antenna gain, and radio wave length, and all confirm Lovell's scattering formula, provided that account is taken of the effective broadening of the scattering pattern of the meteor trail with increasing wave length. The limiting sensitivity of the 9.22 m. 200 kw. radar is determined to be about 9th magnitude. During a strong visual shower the observed increase in visual rates and low-power radar rates, compared to high-power radar rates, is explained by assuming that the magnitude distribution of the shower meteors differs from the normal nonshower distribution.
A UNIFIED PICTURE OF DIFFUSION
Authors: Babbitt J. D.
Published: April 2011

It is shown that if the equation[Formula: see text]where p is a pressure function and Ax a resistive or frictional force, is taken as the fundamental dynamical equation, it is possible to explain diffusion in solutions, in solid solutions, and in an adsorbing solid as well as the interdiffusion of two gases. In diffusion in both liquid and solid solutions the pressure function is the osmotic pressure; in diffusion of adsorbed gases the pressure function is the spreading pressure of the adsorbed layer. Since these pressure functions are thermodynamic properties of the system the pressure gradient is independent of the physical picture assumed for the system. To evaluate Ax, however, it is necessary to assume a specific physical mechanism for the movement of the molecules.
ON THE DIFFUSION OF ADSORBED GASES THROUGH SOLIDS
Authors: Babbitt J. D.
Published: April 2011

The equations for the diffusion of an adsorbed gas through a solid are developed on the assumption that the resistive force is directly proportional to the number of molecules adsorbed, that is, that the resistive force per molecule is constant. The equations are compared with experiment and also with the equations developed in an earlier paper where the assumption was made that the resistive force per molecule is inversely proportional to the number of molecules adsorbed. The equations developed here are not as satisfactory as those developed earlier and it is pointed out that this is a consequence of the fact that heats of adsorption have been found experimentally to decrease as the amount of adsorbed gas increases.
A LINEAR RADIO-FREQUENCY MASS SPECTROMETER
Authors: Redhead P. A.
Published: April 2011

A radio-frequency mass spectrometer is described using a system of electrodes similar to a linear accelerator to obtain velocity selection of tin ions. A beam of ions is directed through a series of axial radio-frequency fields with alternate polarity, and the ion with a velocity (proportional to [Formula: see text]) such that it traverses the individual stages in approximately one-half period of the radio-frequency field, acquires maximum energy from this field. A retarding field region prevents all ions, except the ion with maximum energy, from reaching the collector. An ion beam of large cross section is used. With 20 radio-frequency stages a mass resolution of 1% is obtained.
DIELECTRIC BEHAVIOR AT THE SECOND-ORDER TRANSITIONS IN CHROMIUM SULPHATE, CHROMIUM NITRATE, AND NICKEL NITRATE
Authors: Grayson-Smith H. , Sturrock R. F.
Published: April 2011

In order to obtain further evidence concerning the nature of the second-order transitions which were discovered by Vasileff and Grayson-Smith in certain salts of the iron group metals, dielectric measurements have been made at temperatures, down to about 100 °K. In the case of Cr2(SO4)3∙18H2O the transition at 195 °K. has a marked effect on the dielectric properties, which is clearly due to the freeing of polar molecular groups, so that they can be oriented by an electric field. The entropy of transition is close to R 1n 4, which suggests that two groups per molecule are set free, to take either of two quantized orientations. The dipole moment of the group which is set free can be estimated from the temperature dependence of the dielectric constant just above the transition point and has been found to be 2.17 × 10−18 e.s.u., approximately equal to the dipole moment of the H2O molecule. It is likely, therefore, that the second-order transition in this salt is caused by the freeing of two of the 18 H2O groups. For chromium and nickel nitrates the transitions have no observable effect on the dielectric properties, and it is suggested that in these salts NO3 groups are set free.
RADIOACTIVE DEPOSITS FOUND AT OTTAWA AFTER THE ATOMIC EXPLOSIONS OF JANUARY AND FEBRUARY 1951
Authors: Rose D. C. , Katzman J.
Published: April 2011

Gamma-ray counter equipment, in continuous operation at Ottawa, Canada, indicated that considerable radioactive matter fell on January 29 and again on February 7. The decay period of this material was measured and is consistent with the assumption that the material consisted mainly of products of fission. The fall on January 29 came from an explosion on January 27 and the February 7 material appeared to be three to five days old. The quantity can be estimated only very roughly and is thought to be of the order of one microgram radium equivalent per square meter.
BALLONS DE MATIÈRE PLASTIQUE FABRIQUÉS PAR UN NOUVEAU PROCÉDÉ
Authors: Demers Par Pierre , Grandpré Jean-Louis De
Published: April 2011

not available
TRANSFORMATION AMPLITUDES FOR VECTOR ADDITION OF ANGULAR MOMENTUM; (j3mm′|j3JM)
Authors: Colladay G. S. , Sells R. E. , Falkoff D. L.
Published: April 2011

The transformation amplitudes for the quantum-mechanical vector addition of angular momenta, [Formula: see text] are given.