bluuebunny/crossref_metadata_2025 huggingface dataset:
Differential expression and regulation of the glucokinase gene in liver and islets of Langerhans.
Authors: Iynedjian P B , Pilot P R , Nouspikel T , Milburn J L , Quaade C , Hughes S , Ucla C , Newgard C B
Published: May 2006

Glucokinase, a key regulatory enzyme of glucose metabolism in mammals, provides an interesting model of tissue-specific gene expression. The single-copy gene is expressed principally in liver, where it gives rise to a 2.4-kilobase mRNA. The islets of Langerhans of the pancreas also contain glucokinase. Using a cDNA complementary to rat liver glucokinase mRNA, we show that normal pancreatic islets and tumoral islet cells contain a glucokinase mRNA species approximately 400 nucleotides longer than hepatic mRNA. Hybridization with synthetic oligonucleotides and primer-extension analysis show that the liver and islet glucokinase mRNAs differ in the 5' region. Glucokinase mRNA is absent from the livers of fasted rats and is strongly induced within hours by an oral glucose load. In contrast, islet glucokinase mRNA is expressed at a constant level during the fasting-refeeding cycle. The level of glucokinase protein in islets measured by immunoblotting is unaffected by fasting and refeeding, whereas a 3-fold increase in the amount of enzyme occurs in liver during the transition from fasting to refeeding. From these data, we conclude (i) that alternative splicing and/or the use of distinct tissue-specific promoters generate structurally distinct mRNA species in liver and islets of Langerhans and (ii) that tissue-specific transcription mechanisms result in inducible expression of the glucokinase gene in liver but not in islets during the fasting-refeeding transition.
Evidence that cells expressing luteinizing hormone-releasing hormone mRNA in the mouse are derived from progenitor cells in the olfactory placode.
Authors: Wray S , Grant P , Gainer H
Published: May 2006

In situ hybridization histochemistry and immunocytochemistry were used to study the prenatal expression of luteinizing hormone-releasing hormone (LHRH) cells in the mouse. Cells expressing LHRH mRNA and peptide product were first detected on embryonic day 11.5 (E11.5) in the olfactory pit. On E12.5, the majority of LHRH cells were located on "tracks" extending from the olfactory pit to the base of the telencephalon. From E12.5 to E15.5, LHRH cells were detected in a rostral-to-caudal gradient in forebrain areas. Prior to E12.5, cells expressing LHRH mRNA were not detected in forebrain areas known to contain LHRH cells in postnatal animals. Quantitation of cells expressing LHRH mRNA showed that the number of labeled cells on E12.5 (approximately 800) equaled the number of LHRH cells in postnatal animals, but more than 90% of these cells were located in nasal regions. Between E12.5 and E15.5, the location of LHRH cells shifted. The number of LHRH cells in the forebrain increased, while the number of LHRH cells in nasal regions decreased over this same period. These findings establish that cells first found in the olfactory pit and thereafter in forebrain areas express the LHRH gene and correspond to the position of LHRH immunopositive cells found at these developmental times. To further examine the ontogeny of the LHRH system, immunocytochemistry in combination with [3H]thymidine autoradiography was used to determine when LHRH cells left the mitotic cycle. We show that LHRH neurons exhibit a discrete time of birth, suggesting that they arise as a single neuronal population between E10.0 and E11.0. Postnatal LHRH neurons were "birth-dated" shortly after differentiation of the olfactory placode and before LHRH mRNA was expressed in cells in the olfactory pit. Taken together, these studies support the hypothesis that all LHRH cells in the central nervous system arise from a discrete group of progenitor cells in the olfactory placode and that a subpopulation of these cells migrate into forebrain areas where they subsequently establish an adult-like distribution.
Quasi-random hypergraphs
Authors: Chung F. R. K. , Graham R. L.
Published: May 2006

We describe a large equivalence class of properties shared by most hypergraphs, including so-called random hypergraphs. As a result, it follows that many global properties of hypergraphs are actually consequences of simple local conditions.
Protease nexin-1, an antithrombin with neurite outgrowth activity, is reduced in Alzheimer disease.
Authors: Wagner S L , Geddes J W , Cotman C W , Lau A L , Gurwitz D , Isackson P J , Cunningham D D
Published: May 2006

Protease nexin-1 (PN-1) is a cell-secreted protein that inhibits certain proteases, particularly thrombin, by forming SDS-stable complexes with the catalytic site serine of the protease. PN-1 was recently shown to be identical to a glial-derived neurite-promoting factor/glial-derived nexin present in rat brain. Its neurite outgrowth activity depends on inhibition of thrombin, presumably because thrombin brings about neurite retraction. Here we show that human brain contains PN-1 and that PN-1 activity in brains of individuals with Alzheimer disease (AD) was only 14% of control values (total of 14 AD patients and 7 control individuals). PN-1 activity in the hippocampus, a region with marked neuropathology in AD, was 15% of control values (10 AD patients and 4 control individuals). Western blot analysis indicated a large decrease in free PN-1 protein and an increase in PN-1-containing complexes that comigrated with PN-1-thrombin complexes. Northern blot analysis indicated that PN-1 mRNA levels were about equal in brains from AD patients and control individuals. Thus these results suggest that the decreases in PN-1 activity and free PN-1 protein are due to formation of PN-1-protease complexes.
Salt taxis in Escherichia coli bacteria and its lack in mutants.
Authors: Qi Y L , Adler J
Published: May 2006

Escherichia coli is attracted to a variety of salts. This attraction is highly reduced in mutants missing a known transducer, the methyl-accepting chemotaxis protein I; there is a smaller role for another transducer, the methyl-accepting chemotaxis protein II. We discuss the relation of salt taxis to osmotaxis.
Prostaglandins with antiproliferative activity induce the synthesis of a heat shock protein in human cells.
Authors: Santoro M G , Garaci E , Amici C
Published: May 2006

Prostaglandins (PGs) A1 and J2 were found to potently suppress the proliferation of human K562 erythroleukemia cells and to induce the synthesis of a 74-kDa protein (p74) that was identified as a heat shock protein related to the major 70-kDa heat shock protein group. p74 synthesis was stimulated at doses of PGA1 and PGJ2 that inhibited cell replication, and its accumulation ceased upon removal of the PG-induced proliferation block. PGs that did not affect K562 cell replication did not induce p74 synthesis. p74 was found to be localized mainly in the cytoplasm of PG-treated cells, but moderate amounts were found also in dense areas of the nucleus after PGJ2 treatment. p74 synthesis was not necessarily associated with cytotoxicity or with inhibition of cell protein synthesis. The results described support the hypothesis that synthesis of the 70-kDa heat shock proteins is associated with changes in cell proliferation. The observation that PGs can induce the synthesis of heat shock proteins expands our understanding of the mechanism of action of these compounds whose regulatory role is well known in many physiological phenomena, including the control of fever production.
Molecular cloning and sequence of cDNA encoding polyoma medium tumor antigen-associated 61-kDa protein.
Authors: Walter G , Ferre F , Espiritu O , Carbone-Wiley A
Published: May 2006

Polyoma virus medium tumor antigen forms specific complexes with several cellular proteins; among these is a protein of approximately 61 kDa. With antibodies directed against medium tumor antigen, the 61-kDa protein was purified from human 293 cells that were infected with a hybrid adenovirus and overexpressed medium tumor antigen. The purified 61-kDa protein was partially digested with protease V8, and one of the protease V8 fragments was isolated and partially sequenced. The amino acid sequence information was used to design mixed oligonucleotide probes for screening a cDNA library from human placenta. A clone was isolated that hybridized with two separate probes; the clone contained an insert with an open reading frame for 589 amino acids. By in vitro translation of the transcript from this insert, a protein was generated that had the same size and yielded the same pattern of protease V8 fragments as the original 61-kDa protein. Its amino acid sequence reveals 15 repeats, the majority of which are 39 amino acids long. This protein bears no resemblance to proteins in the data bank that was searched.
Activation of MYC in a masked t(8;17) translocation results in an aggressive B-cell leukemia.
Authors: Gauwerky C E , Huebner K , Isobe M , Nowell P C , Croce C M
Published: May 2006

We have analyzed the oncogene rearrangements involving BCL2 and MYC in the leukemia cells of a patient with an aggressive prolymphocytic leukemia that had an abnormal karyotype including a t(14;18) translocation and a chromosome 17q+. Molecular analysis showed that BCL2 was rearranged in the major breakpoint cluster region and had joined into the immunoglobulin heavy chain gene as in follicular lymphoma. Cloning and sequence analysis of the rearranged MYC gene revealed that MYC was truncated at the Pvu II site at the end of the first exon of MYC and had joined into the regulatory elements of a gene that we called BCL3 (B-cell leukemia/lymphoma 3). The BCL3 locus was mapped to chromosome 17 band q22. We found BCL3 transcribed as a message of 1.7 kilobases in many hematopoietic cell lines representing all hematopoietic lineages. In the patient's leukemia cells, the truncated MYC gene was highly expressed under the influence of BCL3 regulatory elements, leading to an aggressive B-cell leukemia that presumably had been derived from an indolent lymphoma carrying a rearranged BCL2 gene.
Production of human glucocerebrosidase in mice after retroviral gene transfer into multipotential hematopoietic progenitor cells.
Authors: Correll P H , Fink J K , Brady R O , Perry L K , Karlsson S
Published: May 2006

The human glucocerebrosidase (GC) gene has been transferred efficiently into spleen colony-forming unit (CFU-S) multipotential hematopoietic progenitor cells, and production of human GC RNA and protein has been achieved in transduced CFU-S colonies. High-titer retroviral vectors containing the human GC cDNA were constructed. Mouse bone marrow cells were stimulated with hematopoietic growth factors, infected by coculture with producer cells, and injected into lethally irradiated animals. Four vectors were compared with respect to gene-transfer efficiency into CFU-S progenitors. One vector (G vector) required high concentrations of interleukins 3 and 6 during stimulation and coculture for efficient transduction of CFU-S progenitors. The remaining three vectors (NTG, GTN, and GI vectors) transduced these progenitors at infection frequencies approaching 100% using low concentrations of hematopoietic growth factors to stimulate cell division prior to and during the infection. Vectors using the viral long terminal repeat enhancer/promoter to drive the human GC cDNA produced high levels of human GC RNA in the progeny of CFU-S progenitors after gene transfer. When an internal herpes simplex thymidine kinase promoter assisted by a mutant polyoma enhancer was used to drive the human GC cDNA (NTG vector), little or no human GC RNA was detected in transduced CFU-S colonies. All three vectors producing human GC RNA in CFU-S colonies can generate human GC as detected by immunochemical analysis of CFU-S colonies. NTG vector-infected bone marrow cells were transplanted into W/Wv recipients to generate long-term reconstituted mice. The capacity of the viral long terminal repeat and the internal thymidine kinase promoter to direct synthesis of RNA in transduced bone marrow and spleen cells 5 months after bone marrow transplantation reflected the performance of these promoters in NTG-transduced CFU-S colonies.
Alloreactivity studied with mutants of HLA-A2.
Authors: Santos-Aguado J , Crimmins M A , Mentzer S J , Burakoff S J , Strominger J L
Published: May 2006

Based on the crystal structure of HLA-A2.1 and the recognition of a panel of mutant HLA-A2.1 molecules by a large number of alloreactive cytotoxic T lymphocyte clones, a model to explain alloreactivity is described. In this model recognition of an allogeneic major histocompatibility complex molecule by a self-restricted T-cell receptor occurs as the result of accommodation by the receptor of a few amino acid differences in the major histocompatibility complex molecule--i.e., cross-recognition. Alloreactivity is the result of the presence in the foreign antigen binding site of the allogeneic major histocompatibility complex molecule of unusual self-peptides, reactivity to which could not have been eliminated by negative thymic selection.
Different classes of glutamate receptors mediate distinct behaviors in a single brainstem nucleus.
Authors: Dye J , Heiligenberg W , Keller C H , Kawasaki M
Published: May 2006

We have taken advantage of the increasing understanding of glutamate neuropharmacology to probe mechanisms of well-defined vertebrate behaviors. Here we report a set of experiments that suggests distinct roles for two major classes of glutamate receptors in a discrete premotor nucleus of the brainstem. The medullary pacemaker nucleus of weakly electric fish is an endogenous oscillator that controls the electric organ discharge (EOD). Its regular frequency of firing is modulated during several distinct behaviors. The pacemaker nucleus continues firing regularly when isolated in vitro, and modulatory behaviors can be reproduced by stimulating the descending input pathway. Glutamate agonists applied to the pacemaker in vitro produced increases in frequency, while glutamate antagonists selectively blocked stimulus-induced modulations. Experiments with glutamate antagonists in the intact animal resulted in specific effects on two well-characterized behaviors. Our data indicate that these behaviors are separately mediated in the pacemaker by receptors displaying characteristics of the kainate/quisqualate and N-methyl-D-aspartate subtypes of glutamate receptor, respectively.
Fourier-transform mass spectrometry of large molecules by electrospray ionization.
Authors: Henry K D , Williams E R , Wang B H , McLafferty F W , Shabanowitz J , Hunt D F
Published: May 2006

The multiply charged ions produced by electrospray ionization of peptides of molecular masses up to 29 kDa have been successfully introduced into a Fourier transform mass spectrometer of unique capabilities for tandem mass spectrometry, large ion dissociation, and resolution. Electrospray ionization places an unusually high number of charges on a peptide yielding mass/charge (m/z) values of 600-1500; in this range at normal operating pressures (approximately 10(-9) torr; 1 torr = 133.3 Pa) Fourier-transform mass spectrometry resolving power is greater than 100,000. Although only 10(-7) torr pressure has been obtained with the initial interface, the resulting resolving power of 5000 makes possible the resolution of isotopic peaks of multiply charged ions. Mass measuring accuracies of a few daltons for molecular masses up to 17 kDa have also been achieved.
Maltose transport in membrane vesicles of Escherichia coli is linked to ATP hydrolysis.
Authors: Dean D A , Davidson A L , Nikaido H
Published: May 2006

We examined the energy requirement for maltose transport in right-side-out membrane vesicles derived from Escherichia coli. When membrane vesicles were made from strains producing tethered maltose-binding proteins by dilution of spheroplasts into phosphate buffer, those from an F0F1 ATPase-containing (unc+) strain transported maltose in the presence of an exogenous electron donor, such as ascorbate/phenazine methosulfate, at a rate of 1-5 nmol/min per mg of protein, whereas those from an isogenic unc- strain failed to transport maltose. Transport in vesicles obtained from the latter strain could be restored in the presence of electron donors if the vesicles were made to contain NAD+ and either ATP or an ATP-regenerating system. ATP hydrolysis was apparently required for transport, since nonhydrolyzable ATP analogues did not sustain transport. Maltose transport significantly increased ATP hydrolysis in ATP-containing vesicles from unc- cells. Finally, ATP-containing vesicles from unc- strains producing normal maltose-binding proteins could accumulate maltose in the absence of electron donors. These results provide convincing evidence that it is the hydrolysis of ATP that drives maltose transport, and probably also other periplasmic-binding-protein-dependent transport systems.
Turnip crinkle virus defective interfering RNAs intensify viral symptoms and are generated de novo.
Authors: Li X H , Heaton L A , Morris T J , Simon A E
Published: May 2006

Defective interfering (DI) RNAs have been isolated from a broad spectrum of animal viruses and have recently been identified in plant virus infections. Because of their ubiquitous nature, DIs are thought to play an important role in virus replication and yields. DI RNAs have now been found in association with a natural isolate of turnip crinkle virus (TCV-B) and are generated de novo after inoculation of turnip with virus derived from cloned transcripts. DI RNA G, naturally found in the TCV-B isolate, is a mosaic molecule with 5' and 3' viral segments and a repeat of 36 nucleotides at the beginning of the 3' segment. The 5'-terminal 21 nucleotides of DI RNA G were not similar to genomic TCV sequences but did resemble sequences found at the 5' end of other small RNAs associated with TCV (satellite RNAs). DI RNA G interferes with the accumulation of TCV genomic RNA and, unlike other DI RNAs, intensifies the symptoms of its helper virus. Infection of turnip with virus derived from cloned transcripts of TCV-B resulted in de novo generation of a DI RNA, DI1 RNA. DI1 RNA differed from DI RNA G by containing exact 5' and 3' ends of TCV as well as an internal virus segment.
Sex-chromosomal odor types influence the maintenance of early pregnancy in mice.
Authors: Yamazaki K , Beauchamp G K , Bard J , Boyse E A
Published: May 2006

Genetically specified body odors are termed odor types. We showed previously that both the X chromosome and the Y chromosome of the mouse determine differential odor types demonstrable by the behavior of trained mice in the conventional Y-maze test system extensively used in the definition of odor types specified by the major histocompatibility complex (MHC). In the present studies we aimed to ascertain whether perception of X chromosomal and Y chromosomal odor types, like the perception of MHC odor types, exerts a spontaneous influence on reproduction. By making use of reciprocal F1 hybrid males and males of the congenic B6.YAKR strain, males differing solely in their X chromosomes, their Y chromosomes, or both were tested in the conventional pregnancy-block system in which isolated females in early pregnancy are known to be subject to a heightened incidence of failed pregnancy when confronted with the scent of a male whose MHC type differs from that of the missing stud male. As previously established for MHC disparity, perception of X chromosomal disparity or of Y chromosomal disparity between stud and secondary males caused a highly significant rise in the incidence of terminated pregnancy. Thus perception of differential odor types other than those specified by the MHC may also be concerned in aspects of selective reproduction.
Purified, modified eel sodium channels are active in planar bilayers in the absence of activating neurotoxins.
Authors: Shenkel S , Cooper E C , James W , Agnew W S , Sigworth F J
Published: May 2006

A recent study showed that limited trypsin treatment of liposomes containing purified Electrophorus electricus sodium channels activates a sodium radiotracer flux. We now report that similarly treated sodium channels show voltage-gated, tetrodotoxin-sensitive and highly sodium-selective single-channel currents when incorporated into planar lipid membranes. The trypsinized channels opened repeatedly in bursts of several seconds duration, as would be expected for channels whose fast inactivation process had been removed. Furthermore, they have a higher conductance, different voltage-dependence of gating, and a remarkably higher selectivity (PNa/PK = 41) than sodium channels bound by batrachotoxin or other activating neurotoxins; these properties of the trypsinized channels are probably closer to those of channels in intact electrocytes.
Silicon modeling of pitch perception.
Authors: Lazzaro J , Mead C
Published: May 2006

We have designed and tested an integrated circuit that models human pitch perception. The chip receives as input a time-varying voltage corresponding to sound pressure at the ear and produces as output a map of perceived pitch. The chip is a physiological model; subcircuits on the chip correspond to known and proposed structures in the auditory system. Chip output approximates human performance in response to a variety of classical pitch-perception stimuli. The 125,000-transistor chip computes all outputs in real time by using analog continuous-time processing.
Somatostatin-14 and somatostatin-28 induce opposite effects on potassium currents in rat neocortical neurons.
Authors: Wang H L , Bogen C , Reisine T , Dichter M
Published: May 2006

The prosomatostatin-derived peptides somatostatin-14 (Som-14) and somatostatin-28 (Som-28) are believed to act as neurotransmitters in the central nervous system. To examine possible mechanisms by which these peptides induce their physiological actions in brain, the effects of Som-14 and Som-28 on voltage-dependent K+ currents in rat cerebral cortical neurons in culture were examined by using whole-cell patch-clamp techniques. Som-14 increased a delayed rectifier K+ current (IK) in the cortical neurons, while Som-28 reduced IK in the neurons, both in a concentration-dependent manner. Som-14 and Som-28 could induce opposite changes in IK in the same neurons. Elevating intracellular cAMP in the cortical neurons did not modify the effects of Som-14 or Som-28 on IK, indicating that the peptides can regulate this ionic current through cAMP-independent mechanisms. Pretreatment of the neocortical cells with pertussis toxin, which inactivates inhibitory GTP-binding proteins, abolished both Som-14 and Som-28 modulation of IK, indicating that Som-14 and Som-28 receptors are coupled to IK via GTP-binding proteins. These studies show that Som-14 and Som-28 can induce opposite biological effects, suggesting that Som-14 and Som-28, acting through distinct receptors, may function as different neurotransmitters or neuromodulators.
Epstein-Barr virus/complement fragment C3d receptor (CR2) reacts with p53, a cellular antioncogene-encoded membrane phosphoprotein: detection by polyclonal anti-idiotypic anti-CR2 antibodies.
Authors: Barel M , Fiandino A , Lyamani F , Frade R
Published: May 2006

Epstein-Barr virus and the C3d fragment of the third component of complement are specific extracellular ligands for complement receptor type 2 (CR2). However, intracellular proteins that react specifically with CR2 and are involved in post-membrane signals remain unknown. We recently prepared polyclonal anti-idiotypic anti-CR2 antibodies (Ab2) by using the highly purified CR2 molecule as original immunogen. We showed that Ab2 contained anti-idiotypic specificities that mimicked extracellular domains of CR2 and detected two distinct binding sites on CR2 for its specific extracellular ligands, Epstein-Barr virus and C3d. We postulated that Ab2 might also contain specificities that could mimic intracellular domains of CR2. Here we report that Ab2, which did not react with Raji B-lymphoma cell surface components, detected specifically, among all components solubilized from Raji cell membranes, a single intracellular membrane protein of apparent molecular mass of 53 kDa. This protein was identified as the p53 cellular antioncogene-encoded membrane phosphoprotein by analyzing its antigenic properties with Pab1801, a monoclonal anti-p53 antibody, and by comparing its biochemical properties with those of p53. Additionally, solubilized and purified CR2 bound to solubilized p53 immobilized on Pab1801-Sepharose. p53, like CR2, was localized only in purified plasma membranes and nuclei of Raji cells. These data suggest strongly that p53, a cellular antioncogene-encoded phosphoprotein, reacted specifically with CR2 in Raji membranes. This interaction may represent one of the important steps through which CR2 could be involved in human B-lymphocyte proliferation and transformation.
Charybdotoxin inhibits proliferation and interleukin 2 production in human peripheral blood lymphocytes.
Authors: Price M , Lee S C , Deutsch C
Published: May 2006

We demonstrate that blockade of the lymphocyte voltage-gated K+ channel by charybdotoxin (CTX) inhibits lymphocyte mitogenesis. Charybdotoxin blocks conductance with a Ki of 0.3 nM and inhibits mitogen- and antigen-stimulated proliferation with a Ki of 0.5 nM. As opposed to the other blockers of the lymphocyte K+ channel, the inhibition of mitogenesis by CTX can be overcome selectively by exogenous recombinant interleukin 2 (IL-2); endogenous levels of IL-2 in the culture supernatants of stimulated cells are decreased by the presence of CTX. Our results suggest that the voltage-gated K+ channel is either directly or indirectly involved in IL-2 synthesis and/or secretion.
Evolution of a bifunctional enzyme: 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase.
Authors: Bazan J F , Fletterick R J , Pilkis S J
Published: May 2006

The bifunctional rat liver enzyme 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (ATP:D-fructose-6-phosphate 2-phosphotransferase/D-fructose-2,6-bisphosphate 2-phosphohydrolase, EC 2.7.1.105/EC 3.1.3.46) is constructed of two independent catalytic domains. We present evidence that the kinase and bisphosphatase halves of the bifunctional enzyme are, respectively, structurally similar to the glycolytic enzymes 6-phosphofructo-1-kinase and phosphoglycerate mutase. Computer-assisted modeling of the C-terminal bisphosphatase domain reveals a hydrophobic core and active site residue constellation equivalent to the yeast mutase structure; structural differences map to length-variable, surface-located loops. Sequence patterns derived from the structural alignment of mutases and the bisphosphatase further detect a significant similarity to a family of acid phosphatases. The N-terminal kinase domain, in turn, is predicted to form a nucleotide-binding fold that is analogous to a segment of 6-phosphofructo-1-kinase, suggesting that these unrelated enzymes bind fructose 6-phosphate and ATP substrates in a similar geometry. This analysis indicates that the bifunctional enzyme is the likely product of gene fusion of kinase and mutase/phosphatase catalytic units.
Organization of the human lipoprotein lipase gene and evolution of the lipase gene family.
Authors: Kirchgessner T G , Chuat J C , Heinzmann C , Etienne J , Guilhot S , Svenson K , Ameis D , Pilon C , d'Auriol L , Andalibi A
Published: May 2006

The human lipoprotein lipase gene was cloned and characterized. It is composed of 10 exons spanning approximately equal to 30 kilobases. The first exon encodes the 5'-untranslated region, the signal peptide plus the first two amino acids of the mature protein. The next eight exons encode the remaining 446 amino acids, and the tenth exon encodes the long 3'-untranslated region of 1948 nucleotides. The lipoprotein lipase transcription start site and the sequence of the 5'-flanking region were also determined. We compared the organization of genes for lipoprotein lipase, hepatic lipase, pancreatic lipase, and Drosophila yolk protein 1, which are members of a family of related genes. A model for the evolution of the lipase gene family is presented that involves multiple rounds of gene duplication plus exon-shuffling and intron-loss events.
NMR study of the possible interaction in solution of angiotensin II with a peptide encoded by angiotensin II complementary RNA.
Authors: Eaton H L , Austin R E , Fesik S W , Martin S F
Published: May 2006

The potential binding of angiotensin II (Asp-Arg-Val-Tyr-Ile-His-Pro-Phe) (AII) to a peptide encoded by its complementary RNA (Lys-Gly-Val-Asp-Val-Tyr-Ala-Val) (IIA) has been studied by monitoring the 1H NMR spectrum of IIA in aqueous phosphate or Tris.HCl buffer (2H2O) as it is titrated with AII. For molar ratios of AII/IIA ranging from 0.2 to 1.8, the NMR spectra are unchanged as compared to the spectra of the isolated peptides. Based on these findings, the Kd for the putative biomolecular complex of the two peptides under these conditions is calculated to be greater than 10(-4) M. This result does not support the suggestion of Elton et al. [Elton, T. S., Dion, L.D., Bost, K. L., Oparil, S. & Blalock, J. E. (1988) Proc. Natl. Acad. Sci. USA 85, 2518-2522] that AII and IIA engage in high-affinity binding (Kd approximately 5 x 10(-8) M) with each other.
Fourier transform infrared evidence for proline structural changes during the bacteriorhodopsin photocycle.
Authors: Rothschild K J , He Y W , Gray D , Roepe P D , Pelletier S L , Brown R S , Herzfeld J
Published: May 2006

Structural changes involving bacteriohodopsin proline residues have been investigated by Fourier transform infrared difference spectroscopy. Bacteriohodopsin (bR)-producing Halobacteria halobium were grown on a stringent medium containing either ring-perdeuterated proline or 15N-labeled proline. Comparison of the difference spectra obtained from the photoreactions of these labeled bR samples with those for unlabeled bR has led to the assignment of peaks due to proline vibrations. [proline-N15]bR exhibited a 15-cm-1 isotopic downshift of peaks in the 1420- to 1440-cm-1 region of the bR----K and bR----M difference spectra as well as a similar downshift of peaks found in the absolute absorption spectrum of bR. In contrast, [proline-D7]bR did not cause shifts in this region of the difference spectra. These results indicate that one or more prolines undergo a structural rearrangement during the bR photocycle involving the Xaa-Pro C--N peptide bond. This change may be directly coupled to the light-induced isomerization of the retinal chromophore from all-trans-retinal to 13-cis-retinal.
Predictions of structural elements for the binding of Hin recombinase with the hix site of DNA.
Authors: Plaxco K W , Mathiowetz A M , Goddard W A
Published: May 2006

Molecular dynamics simulations were coupled with experimental data from biochemistry and genetics to generate a theoretical structure for the binding domain of Hin recombinase complexed with the hix site of DNA. The theoretical model explains the observed sequence specificity of Hin recombinase and leads to a number of testable predictions concerning altered sequence selectivity for various mutants of protein and DNA.
An altered v-raf is required in addition to v-myc in J3V1 virus for acceleration of murine plasmacytomagenesis.
Authors: Troppmair J , Potter M , Wax J S , Rapp U R
Published: May 2006

We have isolated and molecularly cloned a highly pathogenic virus variant, J3V1, from murine plasmacytomas induced by a combination of pristane and the weakly transforming recombinant retrovirus J3. J3 virus is a derivative of the v-raf/v-myc-carrying J2 virus that was generated by a frameshifting deletion inactivating v-raf in J2. J3V1 contains an additional deletion of 334 base paris in gag, which restores the correct reading frame for v-raf and results in the expression of a p57 gag-raf fusion protein. Reactivation of v-raf in J3 is required for efficient plasmacytoma acceleration in pristane-conditioned BALB/cAn mice.
Description of two genera and species of late Eocene Anthropoidea from Egypt.
Authors: Simons E L
Published: May 2006

In 1987 and 1988 fossils of two previously unknown genera and species of Egyptian early Tertiary Anthropoidea were discovered in the Fayum Depression of Egypt. These are much older than all other Fayum, Oligocene primates and are believed to be Eocene in age. These genera, here named Catopithecus and Proteopithecus, come from a new Fayum site, L-41, and resemble Oligopithecus from the Jebel Qatrani Formation (lower sequence) at quarry E. They are here placed with the latter in a subfamily, Oligopithecinae, that is ranked in the Propliopithecidae. The level of L-41 is separated from quarry E by at least one major unconformity and 47 m of section. Only a maxilla of Proteopithecus is known. Its molars and premolars resemble those of later Fayum Propliopithecus and Aegyptopithecus and do not resemble those of Apidium and Parapithecus, all of which come from the Jebel Qatrani Formation, upper sequence. The type specimen of Catopithecus confirms a lower dental formula of 2-1-2-3, as in Catarrhini. These species appear to be the oldest primates undoubtedly related to humans. Their dental anatomy points to a derivation of Anthropoidea from Eocene adapids.
Partial purification and characterization of a membrane-derived factor regulating neurotransmitter phenotypic expression.
Authors: Adler J E , Schleifer L S , Black I B
Published: May 2006

Cell membrane contact induces the de novo expression of choline O-acetyltransferase (CAT; acetyl-CoA: choline O-acetyltransferase, EC 2.3.1.6) activity in cultures of virtually pure neonatal rat dissociated sympathetic neurons. To identify molecular mechanisms underlying membrane-associated CAT induction, the responsible membrane component was characterized and partially purified. Substantial CAT-inducing activity was found in membranes from adult rat spinal cord and sensory and sympathetic ganglia. Whole brain membranes demonstrated significantly less activity. CAT induction in sympathetic neurons in response to spinal cord membranes was linear with respect to time, after an initial 6-hr lag. It was also linear with respect to concentrations of spinal cord protein from 2 to 100 micrograms per ml. CAT-inducing activity was extracted from spinal cord membranes by incubation with 100 mM NaCl and was purified approximately 5000-fold by DEAE ion-exchange and gel filtration chromatography. The active factor appears to be an extrinsic protein with an apparent molecular mass of 27 kDa. It is inactivated by trypsin and chymotrypsin but is moderately thermostable, retaining activity at 60 degrees C but not at 90 degrees C.
Young—Capelli symmetrizers in superalgebras
Authors: Brini Andrea , Teolis Antonio G. B.
Published: May 2006

Let Super

n

[
U
[unk]
V
] be the
n
th homogeneous subspace of the supersymmetric algebra of
U
[unk]
V
, where
U
and
V
are Z
2
-graded vector spaces over a field K of characteristic zero. The actions of the general linear Lie superalgebras pl(
U
) and pl(
V
) span two finite-dimensional K-subalgebras B and [unk] of End
K
(Super

n

[
U
[unk]
V
]) that are the centralizers of each other. Young—Capelli symmetrizers and Young—Capelli *-symmetrizers give rise to K-linear bases of B and [unk] containing orthogonal systems of idempotents; thus they yield complete decompositions of B and [unk] into minimal left and right ideals, respectively.
Model of the interactions of calichemicin gamma 1 with a DNA fragment from pBR322.
Authors: Hawley R C , Kiessling L L , Schreiber S L
Published: May 2006

An analysis of the binding interactions of several DNA-drug complexes that utilize carbohydrates for DNA recognition has been undertaken. It is proposed that the carbohydrate residues function as general minor groove binding elements, and the stereochemistry of aglycone attachment sites is generally disposed to promote a right-handed helical geometry that is complementary to right-handed DNA. The constitution and stereochemistry of the DNA double-strand cleaving agent calichemicin gamma 1 is consistent with this analysis. Docking experiments with computer-generated models of this drug and a dodecamer duplex that was found to serve as a calichemicin cleavage site were performed to gain insight into the origin of the drug's sequence-selective binding and cutting properties. A model is presented that provides a molecular level understanding of the double-strand cleavage patterns that result from the action of calichemicin gamma 1 on DNA.
Structure of the rat osteocalcin gene and regulation of vitamin D-dependent expression.
Authors: Lian J , Stewart C , Puchacz E , Mackowiak S , Shalhoub V , Collart D , Zambetti G , Stein G
Published: May 2006

The osteocalcin gene encodes a 6-kDa polypeptide, which represents one of the most abundant noncollagenous bone proteins, and the present studies establish that osteocalcin mRNA is detected only in bone tissue. An osteocalcin gene was isolated from a rat genomic DNA library, and sequence analysis indicated that the mRNA is represented in a 953-nucleotide segment of DNA consisting of four exons and three introns. A modular organization of the 5' flanking sequences of the gene is reflected by the presence of at least three classes of regulatory elements, which include the following: (i) RNA polymerase II canonical sequences; (ii) a series of consensus sequences for hormone receptor binding sites and cyclic nucleotide responsive elements consistent with physiologic expression of the osteocalcin gene; and (iii) a 24-nucleotide sequence in the proximal promoter region with a CAAT motif as a central element. We have designated this highly conserved sequence as an "osteocalcin box" since only 2 nucleotide substitutions are found in the rat and human osteocalcin genes. We have demonstrated two factors regulating osteocalcin gene expression. First, a 200-fold increase occurs in normal fetal calvaria osteoblasts producing a mineralizing matrix, compared to confluent osteoblasts in a nonmineralizing matrix. Second, contained within the 600 nucleotides immediately upstream from the transcription start site are sequences that support a 10-fold stimulated transcription of the gene by 1,25-dihydroxyvitamin D.
v-cbl, an oncogene from a dual-recombinant murine retrovirus that induces early B-lineage lymphomas.
Authors: Langdon W Y , Hartley J W , Klinken S P , Ruscetti S K , Morse H C
Published: May 2006

Cas NS-1 is an acutely transforming murine retrovirus that induces pre-B and pro-B cell lymphomas. Molecular cloning showed it was generated from the ecotropic Cas-Br-M virus by sequential recombinations with endogenous retroviral sequences and a cellular oncogene. The oncogene sequence shows no homology with known oncogenes but some similarity to the yeast transcriptional activator GCN4. A 100-kDa gag-cbl fusion protein, with no detectable kinase activity, is responsible for the cellular transformation. The cellular homologue of v-cbl, present in mouse and human DNA, is expressed in a range of hemopoietic lineages.
Trigeminovascular fibers increase blood flow in cortical gray matter by axon reflex-like mechanisms during acute severe hypertension or seizures.
Authors: Sakas D E , Moskowitz M A , Wei E P , Kontos H A , Kano M , Ogilvy C S
Published: May 2006

Cerebral blood flow was measured and compared in 10 symmetrical brain regions following unilateral trigeminal ganglionectomy (n = 13), sham operation (n = 6), or trigeminal root section (rhizotomy) (n = 8) in cats. Multiple determinations were obtained in anesthetized and paralyzed animals using radiolabeled microspheres during (i) normocapnia-normotension, (ii) hypercapnia (5% CO2/95% room air), (iii) angiotensin-induced acute severe hypertension (190 greater than mean arterial blood pressure less than 210 mmHg), or (iv) bicuculline-induced seizures. Flow was symmetrical in all brain regions at rest and during increases induced by hypercapnia in the three groups. During severe hypertension or seizures, marked elevations developed bilaterally (approximately 93% and approximately 130%, respectively). In ganglionectomized animals, increases due to hypertension or seizures were attenuated by 28-32% on the denervated side within cortical gray matter regions corresponding to the anterior, middle, and posterior cerebral arteries. Flow was symmetrical within all brain regions in sham-operated animals and in the rhizotomy group, despite comparable increases in regional cerebral blood flow induced by angiotensin. Hence, the trigeminal nerve mediates blood flow adaptations during severe hypertension and seizures. Furthermore, since trigeminal cell bodies and peripheral axons are destroyed or degenerate following ganglionectomy but not following rhizotomy, local "axon reflex-like" mechanisms mediate these increases in cerebral blood flow.
Coordinate expression of insulin-like growth factor II and its receptor during muscle differentiation.
Authors: Tollefsen S E , Sadow J L , Rotwein P
Published: May 2006

The role of polypeptide growth factors in promoting muscle differentiation is uncharacterized. We have used a fusing skeletal muscle cell line, C2, to examine the endogenous expression of one peptide, insulin-like growth factor II (IGF-II), and its receptor during differentiation. The synthesis of IGF-II is low during proliferation of myoblasts; IGF-II mRNA can be detected only through use of a highly sensitive solution-hybridization assay. Competition binding studies reveal that the IGF-II receptor is similarly nonabundant in myoblasts. During differentiation IGF-II mRNA rises rapidly. A nearly 4-fold increase is seen within 16 hr of onset of the differentiation process, and levels are 25 times higher than those in myoblasts by 96 hr, when myotubes have formed and muscle-specific alpha-actin mRNAs are synthesized. IGF-II accumulates in conditioned culture medium with similar kinetics. The expression of IGF-II receptors on the cell surface increases almost 6-fold 24 hr after the onset of differentiation and remains high. These studies suggest that IGF-II and its receptor are coordinately regulated during myogenic differentiation in C2 cells and that IGF-II may be an autocrine factor for skeletal muscle.
Generation of human monoclonal antibodies to human immunodeficiency virus.
Authors: Gorny M K , Gianakakos V , Sharpe S , Zolla-Pazner S
Published: May 2006

Based on the finding that cells producing antibodies to human immunodeficiency virus (HIV) circulate in the peripheral blood of HIV-infected individuals, attempts were made to immortalize such B cells with Epstein-Barr virus. Mononuclear cells from 58 HIV-seropositive subjects at various stages of HIV infection were transformed, and anti-HIV cell lines were derived from 4 subjects, all of whom were in early stages of infection. Seven of these cell lines have been stable with respect to antibody production for up to 15 months. Three lines are producing IgG antibody to the 41-kDa HIV transmembrane glycoprotein gp41 and 4 produce IgG antibodies to the 24-kDa HIV core protein p24, its precursors and a breakdown product. The antibodies are reactive by ELISA, by radioimmunoprecipitation, and by Western blot, demonstrating the feasibility of producing multiple stable cell lines synthesizing human monoclonal antibodies to HIV by immortalization of peripheral blood cells with Epstein-Barr virus.
Temporal and pharmacological division of fibroblast cyclooxygenase expression into transcriptional and translational phases.
Authors: Raz A , Wyche A , Needleman P
Published: May 2006

We have recently shown that the synthesis of cyclooxygenase [also called prostaglandin (PG) synthase or PG endoperoxide synthase; 8,11,14-icosatrienoate, hydrogen-donor:oxygen oxidoreductase, EC 1.14.99.1] in human dermal fibroblasts is markedly stimulated by the cytokine interleukin 1 (IL-1). We now show that the temporal sequence of the induced synthesis of PG synthase can be separated into an early transcriptional (i.e., actinomycin D inhibitable) phase and a subsequent translational (cycloheximide but not actinomycin D inhibitable) phase and that IL-1 exerts its effect during the transcriptional phase. Phorbol 12-myristate 13-acetate also stimulates synthesis of PG synthase and, together with IL-1, produces a synergistic stimulatory effect. Inhibitors of protein kinase C activation abolished the stimulatory effect of IL-1, suggesting that protein kinase C activation is a critical event in the signal-transduction sequence of the IL-1-induced increase of PG synthase synthesis. The antiinflammatory glucocorticosteroids dexamethasone and triamcinolone, but not progesterone or testosterone, were potent inhibitors of PG synthase synthesis (complete inhibition at 20 nM; IC50, 1 nM) when added during the translational phase of the synthesis sequence. The glucocorticosteroid effect was blocked by RNA and protein synthesis inhibitors. This report suggests that glucocorticosteroids exert their effect via a newly synthesized protein, causing a profound translational control of PG synthase synthesis. This novel mechanism of suppression of arachidonate metabolism is distinct from any influence of steroids on phospholipase A2 activity.
Complete nucleotide sequence of a molecular clone of woodchuck hepatitis virus that is infectious in the natural host.
Authors: Girones R , Cote P J , Hornbuckle W E , Tennant B C , Gerin J L , Purcell R H , Miller R H
Published: May 2006

Woodchuck hepatitis virus (WHV) DNA was cloned from viral particles obtained from the serum of a woodchuck with a naturally acquired infection. The complete nucleotide sequence of the virus genome was determined and found to be 3323 base pairs long. Transfection experiments demonstrated that the recombinant WHV DNA was infectious in each of 18 woodchucks tested and established a chronic carrier state in 1 of 13 neonates and 3 of 5 adult animals. WHV DNA from serum particles from the chronically infected neonate was cloned and the nucleotide sequence of three independent recombinants was compared directly with that of the input recombinant DNA. The consensus sequence of the three progeny genomes was identical to that of the parental DNA sequence. Therefore, transfection of woodchuck livers with recombinant WHV DNA induces active virus replication and gene expression and yields progeny genomes that are faithful copies of the input virus genome.
Molecular mechanism in the formation of a human ring chromosome 21.
Authors: Wong C , Kazazian H H , Stetten G , Earnshaw W C , Van Keuren M L , Antonarakis S E
Published: May 2006

We have characterized the structural rearrangements of a chromosome 21 that led to the de novo formation of a human ring chromosome 21 [r(21)]. Molecular cloning and chromosomal localization of the DNA regions flanking the ring junction provide evidence for a long arm to long arm fusion in formation of the r(21). In addition, the centromere and proximal long arm region of a maternal chromosome 21 are duplicated in the r(21). Therefore, the mechanism in formation of the r(21) was complex involving two sequential chromosomal rearrangements. (i) Duplication of the centromere and long arm of one maternal chromosome 21 occurred forming a rearranged intermediate. (ii) Chromosomal breaks in both the proximal and telomeric long arm regions on opposite arms of this rearranged chromosome occurred with subsequent reunion producing the r(21).