bluuebunny/crossref_metadata_2025 huggingface dataset:
Intron-mediated recombination may cause a deletion in an alpha 1 type I collagen chain in a lethal form of osteogenesis imperfecta.
Authors: Barsh G S , Roush C L , Bonadio J , Byers P H , Gelinas R E
Published: May 2006

To understand the nature of the mutation in type I collagen genes in cells from an infant with the perinatal lethal form of osteogenesis imperfecta (type II), we cloned and sequenced almost 2 kilobases of a normal alpha 1(I) collagen gene and the corresponding region of a mutant alpha 1(I) gene from cell strain CRL 1262. The mutant gene had undergone recombination between two non-homologous introns, which resulted in the loss of three exons coding for 84 amino acids in the triple-helical domain. The deletion predicted the loss of amino acid residues surrounding and including the methionine at the junction between the CNBr peptides alpha 1(I) CB8 and alpha 1(I) CB3, a result confirmed by analysis of the cleavage peptides from the product of the mutant gene. Although large deletions from collagen genes are uncommon causes of the osteogenesis imperfecta type II phenotype, analysis of the de novo change in gene structure in this cell strain suggests that similar rearrangements may have occurred during the evolution of the large collagen genes.
Increased activity of the glucose cycle in the liver: early characteristic of type 2 diabetes.
Authors: Efendić S , Wajngot A , Vranić M
Published: May 2006

The aims were to assess in the mild, lean, type 2 diabetics the activity of the hepatic futile cycle (glucose cycling) in the basal state and during an infusion of glucose and the overall contribution of futile cycling and the relative contributions of the liver and the periphery to excessive hyperglycemia during a glucose challenge. To determine hepatic futile cycling, we studied seven healthy controls (C) and eight mild, lean, type 2 diabetics with decreased oral glucose tolerance test and blood glucose of 123 +/- 4 mg/dl. Experiments included an equilibration period, followed by a 2-hr infusion of glucose at 2 mg/kg of body weight per min. In each subject, two such experiments were performed randomly with infusions of [2-3H]glucose or [3-3H]glucose to calculate, respectively, total glucose output or total glucose phosphorylation and glucose production or irreversible glucose loss. Futile cycling equals the difference between glucose turnover measured by the two tracers. In controls basal glucose production was 2.0 +/- 0.09 mg/kg per min, and it decreased by 75% during glucose infusion; futile cycling could not be detected. Plasma glucose increased by 30% and plasma C-peptide by 88%. In the diabetics total glucose output (2.41 +/- 0.17 mg/kg per min) was larger than glucose production (2.12 +/- 0.16 mg/kg per min), indicating a glucose cycle. During the glucose infusion, glucose production in the diabetics as well as in the controls decreased by 75% (to 0.6 mg/kg per min) despite higher than normal plasma glucose and C-peptide; futile cycling amounted to 0.6 mg/kg per min, which is half of the total glucose output; increase of glucose uptake was essentially only due to phosphorylation of glucose because irreversible uptake increased only marginally; and most glucose taken up by the liver during the glucose challenge reenters the blood stream without being oxidized or polymerized. These findings, when compared to our previous work in which controls were infused with glucose at 4 mg/kg per min, indicate that excessive hyperglycemia in the diabetics during glucose infusion is due to a decrease in irreversible glucose uptake (impaired phosphorylation and futile cycling) and to a decrease in suppression of glucose production. The relative contributions of the liver and periphery to hyperglycemia seem to be almost equivalent. The mechanism behind the increased glucose cycle activity is not clear; it may be due to a relative decrease of glycogen synthase or increase in glucose-6-phosphatase or both.
Cloning an expressed gene shared by the human sex chromosomes.
Authors: Darling S M , Banting G S , Pym B , Wolfe J , Goodfellow P N
Published: May 2006

The existence of genes shared by mammalian sex chromosomes has been predicted on both evolutionary and functional grounds. However, the only experimental evidence for such genes in humans is the cell-surface antigen encoded by loci on the X and Y chromosomes (MIC2X and MIC2Y, respectively), which is recognized by the monoclonal antibody 12E7. Using the bacteriophage lambda gt11 expression system in Escherichia coli and immunoscreening techniques, we have isolated a cDNA clone whose primary product is recognized by 12E7. Southern blot analysis using somatic cell hybrids containing only the human X or Y chromosomes shows that the sequences reacting with the cDNA clone are localized to the sex chromosomes. In addition, the clone hybridizes to DNAs isolated from mouse cells that have been transfected with human DNA and selected for 12E7 expression on the fluorescence-activated cell sorter. We conclude that the cDNA clone encodes the 12E7 antigen, which is the primary product of the MIC2 loci. The clone was used to explore sequence homology between MIC2X and MIC2Y; these loci are closely related, if not identical.
Presynaptic transmitter content controls the number of quanta released at a neuro-neuronal cholinergic synapse.
Authors: Poulain B , Baux G , Tauc L
Published: May 2006

In the buccal ganglion of Aplysia the overloading of the cholinergic presynaptic neuron by exogenous acetylcholine (AcCho) led to an enhancement of the postsynaptic response. The deprivation of choline in the presynaptic neuron by extra- and/or intracellularly applied choline oxidase to prevent AcCho synthesis resulted in a decrease of the postsynaptic response. In both cases, the size of the calculated miniature postsynaptic current (i.e., the size of the quantum) remained unchanged. It was concluded that, for a given stimulation, the number of quanta released (i.e., the quantal content) is directly related to the quantity of AcCho available for release in the presynaptic neuron.
Characterization and distribution of receptors for the atrial natriuretic peptides in mammalian brain.
Authors: Quirion R , Dalpé M , Dam T V
Published: May 2006

Both rat 125I-labeled atrial natriuretic polypeptide [125I-ANP or atrial natriuretic factor fragment ANF-(99-126)] and human 125I-ANP [125I-alpha-ANP or human ANF-(99-126)] bind with high specificity and affinity (Kd = 20-80 pM) to an apparent single class of sites in guinea pig brain. The ligand selectivity pattern demonstrates that ANF-(101-126) greater than ANF-(99-126) greater than ANF-(103-125) greater than ANF-(103-123) on 125I-alpha-ANP binding sites. [International nomenclature starting at the end of the signal peptide of the recently sequenced prepropeptide is used; thus, ANF-(101-126) corresponds to the earlier designation ANF-(8-33), ANF-(103-123) to rat atriopeptin I, and ANF-(103-125) to rat atriopeptin II.] Similar results have been reported in peripheral tissues, which indicate that central and peripheral ANP binding sites have fairly similar structural requirements. In vitro receptor autoradiography shows that in the guinea pig brain, 125I-ANP binding sites are highly concentrated in the external plexiform layer of the olfactory bulb, subfornical organ, various thalamic nuclei, medial geniculate nucleus, and cerebellum. Lower densities are found in the central nucleus of the amygdala, dentate gyrus, hippocampus, and area postrema. Most remaining regions contain much lower densities of sites. In rat brain, 125I-ANP binding sites are differentially distributed, with high densities in the subfornical organ, area postrema, and linings of ventricles but low densities in the thalamus and cerebellum. In monkey brain, 125I-ANP binding sites are concentrated in the cerebellum. The presence of high densities of 125I-ANP binding sites in various brain regions strongly suggests the existence of a family of brain-heart peptides, in analogy to the well-known brain-gut peptides. Moreover, the extensive distribution of 125I-ANP binding sites in mammalian brain suggests that the possible roles of ANP/ANF-like peptides in brain are not restricted to the central regulation of cardiovascular parameters.
Detection and identification of activated oncogenes in spontaneously occurring benign and malignant hepatocellular tumors of the B6C3F1 mouse.
Authors: Reynolds S H , Stowers S J , Maronpot R R , Anderson M W , Aaronson S A
Published: May 2006

Species- and strain-specific spontaneously occurring tumors have been observed in rodents maintained under normal laboratory conditions. Elucidation of the molecular mechanisms associated with the development of these spontaneous tumors may provide a better understanding of tumor development associated with exposure to chemical carcinogens. In view of the high frequencies of oncogene activation shown in rodent tumors induced by known chemical carcinogens, we have investigated oncogene activation in spontaneous tumors of the B6C3F1 mouse and Fischer 344/N rat by DNA transfection techniques. A marked difference in the presence of activated oncogenes in spontaneous rat tumors versus spontaneous mouse liver tumors was observed in this study. All rat tumors tested failed to yield activated oncogenes (0/29), whereas 30% (3/10) of mouse hepatocellular adenomas and 77% (10/13) of hepatocellular carcinomas scored positive by DNA transfection. These transforming genes were identified as an activated Ha-ras gene in all the adenoma transfectants and in 8 of the 10 carcinoma transfectants. The two remaining hepatocellular carcinomas contained transforming genes that appear not to be members of the known ras gene family. The B6C3F1 mouse liver system might provide a very sensitive assay not only for assessing the potential of a chemical to activate a cellular proto-oncogene, but also for detecting various classes of proto-oncogenes that are susceptible to mutational activation.
Biochemical and functional similarities between human eosinophil-derived neurotoxin and eosinophil cationic protein: homology with ribonuclease.
Authors: Gleich G J , Loegering D A , Bell M P , Checkel J L , Ackerman S J , McKean D J
Published: May 2006

Eosinophil-derived neurotoxin (EDN) and eosinophil cationic protein (ECP) were isolated from lysates of human eosinophil granules by gel filtration and ion exchange chromatography on heparin-Sepharose. Radioimmunoassay, using monoclonal antibodies, of fractions from the heparin-Sepharose chromatography showed one peak of EDN activity and two peaks of ECP activity (termed ECP-1 and ECP-2). EDN, ECP-1, and ECP-2 each exhibited heterogeneity in charge and molecular weight when analyzed by two-dimensional nonequilibrium pH gradient electrophoresis and NaDodSO4/PAGE. Digestion of EDN with endoglycosidase F (endo F) decreased its molecular weight and charge heterogeneity. Thus, END likely contains a single complex oligosaccharide. Endo F digestion of ECP-1 and ECP-2 decreased the molecular weight of both polypeptides, indicating that both likely contain at least one complex oligosaccharide. Amino acid sequence analyses showed that ECP-1 and ECP-2 are identical from residue 1 through residue 59 and that the sequences of EDN and ECP are highly homologous (37 of 55 residues identical). Both EDN and ECP NH2-terminal sequences showed significant homology to RNase, especially in regions of the RNase molecule involved in ligand binding. EDN, ECP-1, and ECP-2 had neurotoxic activity, causing the Gordon phenomenon at doses down to 0.15 micrograms when injected into the cisterna magna; the proteins were comparable in their activities. These results indicate that EDN and ECP are related proteins and suggest that they derived from genes associated with the RNase family.
Transcriptional "silencer" element in rat repetitive sequences associated with the rat insulin 1 gene locus.
Authors: Laimins L , Holmgren-König M , Khoury G
Published: May 2006

The enhancer elements from either simian virus 40 or murine sarcoma virus activate the expression of a transfected rat insulin 1 (rI1) gene when placed within 2.0 kilobases or less of the rI1 gene cap site. Inclusion of 4.0 kilobases of upstream rI1 sequence, however, results in a substantial reduction in the enhancer-dependent insulin gene expression. These observations suggested that a negative transcriptional regulatory element was present between 2.0 and 4.0 kilobases of the rI1 sequence. To test this notion, we employed a heterologous enhancer-dependent transcription assay in which the simian virus 40 72-base-pair repeat is linked to a human beta-globin gene. Addition of the upstream rI1 element to this system decreased the level of enhancer-dependent beta-globin transcription by a factor of 5 to 15. This rI1 "silencer" element functions in a manner relatively independent of position and orientation and requires a cis-dependent relationship to the transcription unit on which it acts. Thus, the silencer sequence seems to have a number of the characteristics of enhancer elements, and we suggest that it may function by the converse of the enhancer mechanism. The rI1 silencer sequence was identified as a member of a long interspersed rat repetitive family. Thus, a potential role for certain repetitive sequences interspersed throughout the eukaryotic genome may be to regulate gene expression by retaining transcriptional activity within defined domains.
Human histone genes map to multiple chromosomes.
Authors: Tripputi P , Emanuel B S , Croce C M , Green L G , Stein G S , Stein J L
Published: May 2006

Histone genes were mapped to at least three human chromosomes by Southern blot analysis of DNAs from a series of mouse-human somatic cell hybrids (using 32P-labeled cloned human histone DNA as probes). Chromosome assignment was confirmed by in situ hybridization of radiolabeled histone gene probes (3H-labeled) to metaphase chromosomes. One human histone gene cluster (lambda HHG41) containing an H3 and H4 gene resides only on chromosome 1, whereas other clusters containing core (H3, H4, H2A, and H2B) alone (lambda HHG17) or core together with H1 histone genes (lambda HHG415) have been assigned to chromosomes 1, 6, and 12. These results suggest that the multigene family of histone coding sequences that reside in a series of clusters may be derived from a single cluster containing one each of the genes for the five principal classes of histone proteins. During the course of evolution, a set of events, probably involving reduplication, sequence modification, and recombination, resulted in the present pattern of human histone gene distribution among several chromosomes.
Activation of rat c-raf during transfection of hepatocellular carcinoma DNA.
Authors: Ishikawa F , Takaku F , Hayashi K , Nagao M , Sugimura T
Published: May 2006

Rat c-raf was found to be activated in a transformant obtained with DNA of a hepatocellular carcinoma induced by 2-amino-3-methylimidazo[4,5-f]quinoline. This activated c-raf was cloned in a cosmid vector and actively transforming clones were obtained. Comparison of the restriction maps of this activated c-raf and cloned normal rat c-raf revealed a recombination in the 5'-terminal region of the activated form of this gene. The recombined DNA was shown to be actively transcribed and possibly to form a fused mRNA with c-raf, which is slightly smaller than normal c-raf mRNA. Since this recombination was not detected in the original tumor by Southern blot analysis, it presumably occurred during transfection.
Specific binding of human corticosteroid-binding globulin to cell membranes.
Authors: Hryb D J , Khan M S , Romas N A , Rosner W
Published: May 2006

Specific binding sites for corticosteroid-binding globulin were detected on membranes prepared from human prostates. The binding sites are typical of membrane receptors: they are saturable and specific and have high affinity. There was little specific binding at 4 degrees C and 23 degrees C. Maximal specific binding was obtained at 37 degrees C. Scatchard analysis revealed the presence of a single set of binding sites with an apparent dissociation constant of 8.7 X 10(-7) M and a binding capacity of 22 pmol/mg of membrane protein. The sites were specific for corticosteroid-binding globulin; binding was not inhibited by human testosterone/estradiol-binding globulin, by albumin, or by transferrin. The density of specific binding sites in membranes obtained from several organs from the rhesus monkey is consistent with the hypothesis that corticosteroid-binding globulin is involved in the transport of steroid hormones into target tissues.
A proton NMR study of the mechanism of the erythrocyte glucose transporter.
Authors: Wang J F , Falke J J , Chan S I
Published: May 2006

A generalizable 1H NMR technique is developed and used to monitor beta-D-glucose binding to glucose transport sites on erythrocyte membranes. This technique provides resolution of beta-D-glucose binding sites on opposite sides of the membrane, thereby enabling study of recruitment of transport sites from one side of the membrane to the other. Cytochalasin B, which competitively and specifically inhibits glucose binding to the inward-facing glucose transport site, recruits all glucose transport sites on both sides of the membrane to the inward-facing conformation. This result strongly supports a one-site model in which a single transport site alternates between distinct inward- and outward-facing conformations. The rate-limiting step in the transport process is translocation of the transport site between the two conformations, since the beta-D-glucose binding and dissociation events at both the inward- and outward-facing transport sites are shown to be fast compared to the known turnover rate of the glucose transport cycle. A model is presented for the transport machinery in which the glucose molecule binds in a cleft between channel-forming transmembrane helices, and during the transport event a sliding barrier moves past the transport site, thereby exposing the site to the opposite solution compartment.
Kinetic diagram and free energy diagram for kinesin in microtubule-related motility.
Authors: Hill T L
Published: May 2006

The theoretical formalism that shows how biochemistry (ATPase activity) is related to mechanics in muscle contraction can be extended to the role of kinesin in microtubule-related motility. The main features added are the freedom of kinesin molecules to come and go from the motility complex and the small number of operative kinesin molecules in some systems. The starting points for this kind of approach are the kinetic diagram of biochemical states and the corresponding free energy diagram for these states. These topics are introduced and discussed here in relation to those systems that are presumed to use kinesin.
Tissue tropism of a leukemogenic murine retrovirus is determined by sequences outside of the long terminal repeats.
Authors: Wolff L , Ruscetti S
Published: May 2006

Although it has been previously determined that the long terminal repeat (LTR) sequences of several murine retroviruses specify the major tissue tropism of leukemias they induce, data reported here show that the LTR is not responsible for tissue tropism in the case of all leukemogenic viruses. In an effort to determine whether LTR sequences of the acute erythroleukemia-inducing spleen focus-forming virus (SFFV), like those of the other murine leukemia viruses, are uniquely required to confer tissue specificity to the virus, we prepared recombinant SFFVs in which the LTR region containing promoter and enhancer functions was replaced with analogous LTR regions from Friend and Moloney ecotropic and mink cell focus-inducing viruses. It was found that all of the SFFV constructs, even those with a LTR derived from lymphoma-inducing viruses such as Moloney murine leukemia virus, transformed erythroid cells in vitro and induced exclusively an erythroid disease. These results demonstrate that sequences in SFFV that determine the tissue-specific nature of the disease reside outside the LTR.
T cells can be cytotoxic without making interleukin 2: a model of separate pathways of induction.
Authors: Bellgrau D , Talmage D W
Published: May 2006

The thoracic duct lymphocytes from rats previously injected with ultraviolet-light-irradiated allogeneic lymphocytes were grown for 4 days with alloantigen, with or without Con A-induced lymphokine factors, and then for 3 days with the lymphokines alone. They were then tested for their cytoxicity and for their capacity to make interleukin 2 (IL-2) in response to antigen. The results show that T helper cells specific for both class I and class II antigens of the major histocompatibility complex were removed from the circulation by the injection of ultraviolet-irradiated alloantigen. However, precursors of cytotoxic cells remained and appeared to lose their OX-19 markers during activation. We have interpreted the results by using a speculative model that involves separate pathways of induction to cytotoxicity and IL-2 synthesis. We propose that the OX-19 marker is associated with the interleukin 1 receptor and that the latter is required for the IL-2 production pathway but not for activation to cytotoxicity.
Growth-associated protein, GAP-43, a polypeptide that is induced when neurons extend axons, is a component of growth cones and corresponds to pp46, a major polypeptide of a subcellular fraction enriched in growth cones.
Authors: Meiri K F , Pfenninger K H , Willard M B
Published: May 2006

Growth-associated protein, GAP-43, is a polypeptide that is induced in neurons when they grow axons. We show by means of subcellular fractionation and immunohistochemical localization that GAP-43 is a component of neuronal growth cones as well as growing neurites; it is similar to a major phosphoprotein, pp46, of a growth cone-enriched subcellular fraction. These conclusions are consistent with the possibility that the induction of GAP-43/pp46 is an important event in the establishment of a productive growth state in which a neuron is competent to extend an axon.
Photoinduced oxidation of a water-soluble manganese(III) porphyrin
Authors: Maliyackel Anthony C. , Otvos John W. , Spreer Larry O. , Calvin Melvin
Published: May 2006

The photoinduced oxidation of tetra(
N
-methyl-4-pyridyl)porphyrinmanganese(III) has been achieved in homogeneous solution. The manganese porphyrin was used as an electron donor in a three-component system with tris-(2,2′-bipyridine)ruthenium(II) as the photosensitizer and chloropentaamminecobalt(III) as the electron acceptor. The photooxidized manganese porphyrin is unstable in aqueous solution, reverting to the starting manganese(III) porphyrin. The oxidation of manganese(III) porphyrin and the subsequent reduction of the oxidized porphyrin can be cycled repeatedly.
Human fibroblast collagenase: glycosylation and tissue-specific levels of enzyme synthesis.
Authors: Wilhelm S M , Eisen A Z , Teter M , Clark S D , Kronberger A , Goldberg G
Published: May 2006

Human skin fibroblasts secrete collagenase as two proenzyme forms (57 and 52 kDa). The minor (57-kDa) proenzyme form is the result of a partial posttranslational modification of the major (52-kDa) proenzyme through the addition of N-linked complex oligosaccharides. Human endothelial cells as well as fibroblasts from human colon, cornea, gingiva, and lung also secrete collagenase in two forms indistinguishable from those of the skin fibroblast enzyme. In vitro tissue culture studies have shown that the level of constitutive synthesis of this fibroblast-type interstitial collagenase is tissue specific, varies widely, and correlates with the steady-state level of a single collagenase-specific mRNA of 2.5 kilobases. The tumor promoter, phorbol 12-myristate 13-acetate, apparently blocks the control of collagenase synthesis resulting in a similarly high level of collagenase expression (approximately equal to 3-7 micrograms of collagenase per 10(6) cells per 24 hr) in all examined cells. The constitutive level of synthesis of a 28-kDa collagenase inhibitor does not correlate with that of the enzyme. Phorbol 12-myristate 13-acetate stimulates the production of this inhibitor that in turn modulates the activity of collagenase in the conditioned media. As a result, the apparent activity of the enzyme present in the medium does not accurately reflect the rate of its synthesis and secretion.
Link protein cDNA sequence reveals a tandemly repeated protein structure.
Authors: Doege K , Hassell J R , Caterson B , Yamada Y
Published: May 2006

Link protein stabilizes the cartilage proteoglycan/hyaluronic acid aggregate by binding to both components. We screened a cDNA library prepared from rat chondrosarcoma mRNA in the lambda gt11 expression vector with monoclonal antibodies and polyclonal antisera to link protein. We obtained a clone for two-thirds of the link protein cDNA and identified it based on its deduced amino acid sequence. There are four RNA transcripts for link protein, ranging from 1.5 to 5.5 kilobases in size. The deduced amino acid sequence for link protein shows two domains of 100 residues each, which share 44% homology; within each domain is a 19-residue stretch 74% homologous with its counterpart. This structure indicates that link protein may have been formed by gene duplication.
Genes encoding major light-harvesting polypeptides are clustered on the genome of the cyanobacterium Fremyella diplosiphon.
Authors: Conley P B , Lemaux P G , Lomax T L , Grossman A R
Published: May 2006

The polypeptide composition of the phycobilisome, the major light-harvesting complex of prokaryotic cyanobacteria and certain eukaryotic algae, can be modulated by different light qualities in cyanobacteria exhibiting chromatic adaptation. We have identified genomic fragments encoding a cluster of phycobilisome polypeptides (phycobiliproteins) from the chromatically adapting cyanobacterium Fremyella diplosiphon using previously characterized DNA fragments of phycobiliprotein genes from the eukaryotic alga Cyanophora paradoxa and from F. diplosiphon. Characterization of two lambda-EMBL3 clones containing overlapping genomic fragments indicates that three sets of phycobiliprotein genes--the alpha- and beta-allophycocyanin genes plus two sets of alpha- and beta-phycocyanin genes--are clustered within 13 kilobases on the cyanobacterial genome and transcribed off the same strand. The gene order (alpha-allophycocyanin followed by beta-allophycocyanin and beta-phycocyanin followed by alpha-phycocyanin) appears to be a conserved arrangement found previously in a eukaryotic alga and another cyanobacterium. We have reported that one set of phycocyanin genes is transcribed as two abundant red light-induced mRNAs (1600 and 3800 bases). We now present data showing that the allophycocyanin genes and a second set of phycocyanin genes are transcribed into major mRNAs of 1400 and 1600 bases, respectively. These transcripts are present in RNA isolated from cultures grown in red and green light, although lower levels of the 1600-base phycocyanin transcript are present in cells grown in green light. Furthermore, a larger transcript of 1750 bases hybridizes to the allophycocyanin genes and may be a precursor to the 1400-base species.
Regional mapping of human chromosome 19: organization of genes for plasma lipid transport (APOC1, -C2, and -E and LDLR) and the genes C3, PEPD, and GPI.
Authors: Lusis A J , Heinzmann C , Sparkes R S , Scott J , Knott T J , Geller R , Sparkes M C , Mohandas T
Published: May 2006

We report the regional mapping of human chromosome 19 genes for three apolipoproteins and a lipoprotein receptor as well as genes for three other markers. The regional mapping was made possible by the use of a reciprocal whole-arm translocation between the long arm of chromosome 19 and the short arm of chromosome 1. Examination of three separate somatic cell hybrids containing the long arm but not the short arm of chromosome 19 indicated that the genes for apolipoproteins CI, CII, and E (APOC1, APOC2, and APOE, respectively) and glucose-6-phosphate isomerase (GPI) reside on the long arm, whereas genes for the low density lipoprotein receptor (LDLR), complement component 3 (C3), and peptidase D (PEPD) reside on the short arm. When taken together with previous studies, our results suggest the following physical gene map: pter-LDLR-C3-p13.2-PEPD-centromere-(APOE, APOC1, APOC2, GPI)-qter. In addition, we have isolated a single lambda phage carrying both APOC1 and part of APOE. These genes are tandemly oriented and are separated by about 6 kilobases of genomic DNA. Since previous family studies indicate tight linkage of APOE and APOC2, the apolipoprotein genes APOC1, APOC2, and APOE form a tight complex on the long arm of chromosome 19, suggesting the possibility of coordinate regulation.
Interaction between a "processed" ovalbumin peptide and Ia molecules.
Authors: Buus S , Colon S , Smith C , Freed J H , Miles C , Grey H M
Published: May 2006

The binding of 125I-labeled immunogenic peptides to purified Ia molecules in detergent solution was examined by equilibrium dialysis. We used the chicken ovalbumin peptide ovalbumin-(323-339)-Tyr, which is immunogenic in the BALB/c mouse and restricted to I-Ad. 125I-labeled ovalbumin-(323-339)-Tyr was shown to bind to I-Ad but not to I-Ed, I-Ek, or I-Ak. This binding was inhibited by unlabeled ovalbumin-(323-339) but not by ovalbumin-(329-339), which is the longest N-terminally truncated peptide that fails to stimulate any of the I-Ad-restricted hybridomas that have been raised to ovalbumin-(323-339)-Tyr. As a further specificity control, we also used the chicken egg lysozyme peptide Tyr-(46-61), which has recently been studied by similar methods [Babbitt, B. P., Allen, P. M., Matsueda, G., Haber, E. & Unanue, E. R. (1985) Nature (London) 317, 359-361]. We have confirmed that it bound to I-Ak but not to I-Ek, I-Ad, or I-Ed. Thus, a specific interaction between Ia and antigen that correlates with the major histocompatibility complex restriction was demonstrated, strongly arguing in favor of a determinant selection hypothesis for such restriction.
Variable expression of the translocated c-abl oncogene in Philadelphia-chromosome-positive B-lymphoid cell lines from chronic myelogenous leukemia patients.
Authors: Konopka J B , Clark S , McLaughlin J , Nitta M , Kato Y , Strife A , Clarkson B , Witte O N
Published: May 2006

The consistent cytogenetic translocation of chronic myelogenous leukemia (the Philadelphia chromosome, Ph1) has been observed in cells of multiple hematopoietic lineages. This translocation creates a chimeric gene composed of breakpoint-cluster-region (bcr) sequences from chromosome 22 fused to a portion of the abl oncogene on chromosome 9. The resulting gene product (P210c-abl) resembles the transforming protein of the Abelson murine leukemia virus in its structure and tyrosine kinase activity. P210c-abl is expressed in Ph1-positive cell lines of myeloid lineage and in clinical specimens with myeloid predominance. We show here that Epstein-Barr virus-transformed B-lymphocyte lines that retain Ph1 can express P210c-abl. The level of expression in these B-cell lines is generally lower and more variable than that observed for myeloid lines. Protein expression is not related to amplification of the abl gene but to variation in the level of bcr-abl mRNA produced from a single Ph1 template.
Polymorphonuclear leukocyte histamine receptors: occurrence in cell surface clusters and their redistribution during locomotion.
Authors: Petty H R , Francis J W
Published: May 2006

A univalent and bioactive fluorescent derivative of histamine bound to the surface of human polymorphonuclear leukocytes; free histamine was found to compete with this derivative for binding sites. Histamine H2-receptor specificity was indicated by binding inhibition experiments using cimetidine (H2-specific) but not diphenhydramine (H1-specific). Video-intensification fluorescence microscopy was used to determine the distribution of histamine receptors in living polymorphonuclear leukocytes. Receptors appeared as randomly distributed clusters upon stationary cells. During random locomotion, receptors were restricted to the ends of pseudopods, whereas chemotaxis led to receptor localization at lamellipodia and uropods. Ligand-receptor complexes were restricted to the cell surface, as shown by quenching exterior fluorescence with crystal violet. Therefore, pinocytic uptake cannot account for the observed receptor localization or clustering. As a further control, the lipid analog 1,1-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine remained uniformly distributed during all conditions. Histamine-mediated inhibition of adherence may be related to formation of ligand-receptor membrane domains at adherence sites.
Mitochondrial DNA differentiation in North Atlantic eels: Population genetic consequences of an unusual life history pattern
Authors: Avise John C. , Helfman Gene S. , Saunders Nancy C. , Hales L. Stanton
Published: May 2006

A survey of restriction site polymorphism in the mitochondrial DNA (mtDNA) of the American eel
Anguilla rostrata
showed no genetic divergence among samples from a 4000-km stretch of North America coastline. Lack of geographic differentiation in mtDNA over such a large area contrasts sharply with results for terrestrial and freshwater vertebrates and is most likely attributable to the extraordinary life history of these catadromous fishes, which involves perhaps a single spawning population in the western tropical mid-Atlantic Ocean and subsequent widespread dispersal of larvae by ocean currents. However, samples of the European eel (nominally
Anguilla anguilla
) are highly distinct from
A. rostrata
in mtDNA genotype (distinguishable by 11 of 14 restriction endonucleases), contradicting some previous suggestions that the two forms belong to the same panmictic population. Results of this study emphasize the importance of life history in shaping population genetic structure.
Isolation of molecular probes associated with the chromosome 15 instability in the Prader-Willi syndrome.
Authors: Donlon T A , Lalande M , Wyman A , Bruns G , Latt S A
Published: May 2006

Flow cytometry and recombinant DNA techniques have been used to obtain reagents for a molecular analysis of the Prader-Willi syndrome (PWS). HindIII total-digest libraries were prepared in lambda phage Charon 21A from flow-sorted inverted duplicated no. 15 human chromosomes and propagated on recombination-proficient (LE392) and recBC-, sbcB- (DB1257) bacteria. Twelve distinct chromosome 15-specific probes have been isolated. Eight localized to the region 15q11----13. Four of these eight sublocalized to band 15q11.2 and are shown to be deleted in DNA of one of two patients examined with the PWS. Heteroduplex analysis of two of these clones, which grew on DB1257 but not on LE392, revealed stem-loop structures in the inserts, indicative of inverted, repeated DNA elements. Such DNA repeats might account for some of the cloning instability of DNA segments from proximal 15q. Analysis of the genetic and physical instability associated with the repeated sequences we have isolated from band 15q11.2 may elucidate the molecular basis for the instability of this chromosomal region in patients with the PWS or other diseases associated with chromosomal abnormalities in the proximal long arm of human chromosome 15.
Genetic analysis of mutations at the fused locus in the mouse.
Authors: Greenspan R J , O'Brien M C
Published: May 2006

Mutations at the fused (Fu) locus on chromosome 17 of the mouse disrupt embryonic development by altering the organization of the neurectoderm. We have examined the interactions among several independent fused mutations, including a deletion of the locus, to define the nature of the mutant defects. Closely linked restriction fragment length polymorphisms made possible the unambiguous identification of genotype in all progeny. Tests with the deletion, as well as interactions among alleles, indicate that all three spontaneous mutations are "gain of function" defects. Comparisons of relative viabilities of the various mutant combinations rank them into a series of increasing severity and place constraints on possible modes of gene action.
Activation of human B cells mediated through two distinct cell surface differentiation antigens, Bp35 and Bp50.
Authors: Clark E A , Ledbetter J A
Published: May 2006

Two human B-cell differentiation antigens, Bp35 and Bp50, apparently play distinct roles as signal receptors in B-cell activation. Monoclonal antibodies (mAbs) to either Bp35 or Bp50 deliver positive signals to B cells that stimulate their transition through the cell cycle. mAb to Bp35, like anti-immunoglobulin antibodies, functions principally to activate resting B cells to become competent to enter the G1 phase of the cell cycle. In contrast, mAb to Bp50, a 50-kDa polypeptide expressed on all B cells, functions to stimulate activated B cells to traverse the cell cycle. mAb to Bp35, like anti-immunoglobulin antibodies, activates tonsillar B cells and induces low levels of B-cell proliferation. In contrast, anti-Bp50 mAb alone neither activates B cells nor induces B cells to proliferate but, together with anti-Bp35 or anti-immunoglobulin, augments B-cell proliferation. In this respect the action of anti-Bp50 antibody resembles the activity of B-cell growth factor(s) (BCGF). As little as 0.05 microgram of anti-Bp50 per ml is needed to augment proliferation and, like BCGF, anti-Bp50 is effective even when added 12-24 hr after B cells are activated with anti-immunoglobulin or anti-Bp35. Without additional exogenous signals, anti-Bp35 and anti-Bp50 together induce strong proliferation of purified resting B cells. These results suggest that the Bp35 and Bp50 surface molecules function in the regulatory control of B-cell activation and progression through the cell cycle.
Presence and formation of codeine and morphine in the rat.
Authors: Donnerer J , Oka K , Brossi A , Rice K C , Spector S
Published: May 2006

Endogenous codeine and morphine were identified in rat brain by immunological determination following HPLC. To demonstrate occurrence of a biosynthetic pathway to morphine in mammals similar to that used by the poppy plant, (+)-salutaridine, (-)-thebaine, and (-)-codeine were administered to rats intravenously. These compounds, which are intermediates in the synthesis of morphine in Papaver somniferum, caused a marked increase in the codeine and morphine levels in rat tissues. This provides evidence for a biosynthetic pathway to morphine in mammalians.
Nucleotide sequences for the gene junctions of human respiratory syncytial virus reveal distinctive features of intergenic structure and gene order.
Authors: Collins P L , Dickens L E , Buckler-White A , Olmsted R A , Spriggs M K , Camargo E , Coelingh K V
Published: May 2006

Complete sequences for the intergenic regions of the genome of human respiratory syncytial virus were obtained by dideoxynucleotide sequencing using synthetic oligonucleotides. These experiments established that the 10 respiratory syncytial viral genes are arranged, without additional intervening genes, in the order 3' 1C-1B-N-P-M-1A-G-F-22K-L 5'. For the first nine genes, the exact gene boundaries were identified by comparison of the genomic sequences with previously determined mRNA sequences. The intergenic regions varied in length from 1 to 52 nucleotides and lacked any obvious conserved features of primary or secondary structure except that each sequence ended (3' to 5') with an adenosine residue. The exact start site of the 10th gene, the L gene, was not determined. However, RNA blot hybridization using a synthetic oligonucleotide designed from the genomic sequence mapped the L gene to within 54 nucleotides of the end of the penultimate 22K gene. The lack of conservation of chain length and nucleotide sequence for the respiratory syncytial viral intergenic regions, together with the complexity of the genetic map, contrasts with previous observations for other nonsegmented negative-strand viruses.
The pH dependence of the mechanism of reaction of hydrogen peroxide with a nonaggregating, non-mu-oxo dimer-forming iron (III) porphyrin in water.
Authors: Bruice T C , Zipplies M F , Lee W A
Published: May 2006

The reaction of hydrogen peroxide with 5, 10,15,20-tetrakis(2,6-dimethyl-3-sulfonatophenyl)porphinato- iron(III) hydrate [(P)FeIII(H2O)] has been investigated in water between pH 1 and pH 12. The water-soluble (P)FeIII(H2O) neither aggregates nor forms a mu-oxo dimer. The pH dependence and rate-limiting second-order rate constants (kly) for oxygen transfer from H2O2 and HO2- to the iron(III) porphyrin were determined by trapping of the resultant higher-valent iron-oxo porphyrin species with 2,2'-azinodi(3-ethylbenzthiazoline)-6-sulfonate (ABTS). Reactions were monitored spectrophometrically by following the appearance of the radical ABTS.+. From a plot of the logarithm of the determined second-order rate constants for reaction of hydrogen peroxide with iron(III) porphyrin vs. pH, the composition of the transition states can be assigned for the three reactions that result in oxygen transfer to yield a higher-valent iron-oxo porphyrin species. The latter not only reacts with ABTS to provide ABTS.+ in a peroxidase-type reaction but also reacts with hydrogen peroxide to provide O2 in a catalase-type reaction. The nitrogen base 2,4,6-collidine serves as a catalyst for oxygen transfer from hydrogen peroxide to the (P)FeIII-(H2O) and (P)FeIII(HO) species. The preferred mechanism involves a 1,2-proton shift concerted with heterolytic cleavage of the peroxide O-O bond. An analogous mechanism is believed to occur in the peroxidase enzymes.
Antibodies to the evolutionarily conserved amino-terminal region of the v-myb-encoded protein detect the c-myb protein in widely divergent metazoan species.
Authors: Boyle W J , Lipsick J S , Baluda M A
Published: May 2006

Antibodies directed against a bacterial fusion protein that contains the domain encoded by the highly evolutionarily conserved 5' one-third of the v-myb oncogene of avian myeloblastosis virus (AMV) detect the protein products of various members of the myb gene family. Immunoprecipitation or immunoblot analyses with these antibodies yielded the following information. First, the products of the v-myb oncogenes of AMV (p48v-myb) and of E26 virus (p135gag-myb-ets) contain this highly conserved amino acid sequence, as previously hypothesized. Second, p75c-myb, the product of the chicken c-myb protooncogene, also contains this protein domain. Third, these antibodies have identified the products of the human, murine, and Drosophila c-myb genes, which were all found to be nuclear proteins of Mr 75,000-80,000. The human c-myb protein product is present in immature cells of the erythroid, myeloid, and lymphoid lineages.
A microtubule-activated ATPase from sea urchin eggs, distinct from cytoplasmic dynein and kinesin.
Authors: Collins C A , Vallee R B
Published: May 2006

We report an ATPase activity, present in sea urchin egg cytosol, that is activated by microtubules. The activity sediments at 10 S in sucrose gradients and is clearly distinct from activities at 12 S and 20 S due to cytoplasmic dynein. Potent activation of the ATPase is observed when endogenous egg tubulin is induced to assemble with taxol or when exogenous taxol-stabilized pure brain tubulin microtubules or flagellar outer-doublet microtubules are added. No activation by tubulin subunits or taxol alone is detectable. In contrast to flagellar or cytoplasmic dynein, the microtubule-activated enzyme is unaffected by vanadate or by nonionic detergents and hydrolyzes GTP in addition to ATP. In contrast to kinesin, it cosediments with microtubules in the presence or absence of ATP. The microtubule-activated enzyme may have a role in microtubule-based motility.
Efficient cloning of genes of
Neurospora crassa
Authors: Vollmer Steven J. , Yanofsky Charles
Published: May 2006

We have constructed a genomic library of
Neurospora crassa
DNA in a cosmid vector that contains the dominant selectable marker for benomyl resistance. The library is arranged to permit the rapid cloning of
Neurospora
genes by either sib-selection or colony-hybridization protocols. Detailed procedures for the uses of the library are described. By use of these procedures, a modest number of unrelated genes have been isolated. The cloning of
trp-3
, the structural gene for the multifunctional enzyme tryptophan synthetase (tryptophan synthase, EC 4.2.1.20), is reported in detail; its identity was verified by restriction fragment length polymorphism mapping. The strategies described in this paper should be of use in the cloning of any gene of
Neurospora
, as well as genes of other lower eukaryotes.
Identification of conserved and divergent domains within the envelope gene of the acquired immunodeficiency syndrome retrovirus.
Authors: Willey R L , Rutledge R A , Dias S , Folks T , Theodore T , Buckler C E , Martin M A
Published: May 2006

The nucleotide sequences of the envelope genes of an African and a North American acquired immunodeficiency syndrome (AIDS) viral isolate have been determined. When their deduced amino acid sequences were aligned with the envelopes of the lymphoadenopathy and AIDS-associated retrovirus isolates, conserved and divergent regions were readily identified. Hypervariable stretches of 28-74 amino acids, exhibiting 20-30% amino acid identity at each position and characterized by reciprocal insertions and deletions, were confined to the gp120 external envelope protein. The origin and clinical implications of the AIDS viral env gene diversity are discussed.
In vitro
transcription of infectious RNAs from full-length cDNAs of tobacco mosaic virus
Authors: Meshi Tetsuo , Ishikawa Masayuki , Motoyoshi Fusao , Semba Kentaro , Okada Yoshimi
Published: May 2006

We have cloned full-length double-stranded cDNAs of tobacco mosaic virus (TMV) (tomato strain L) RNA into a transcription vector, pPM1, which facilitates the correct transcription initiation from the first nucleotide of the inserted double-stranded cDNA, corresponding to the 5′ end of TMV RNA. When plasmid DNA is linearized at a unique restriction site (
Mlu
I) introduced just downstream of the double-stranded cDNA insert and used as a template for
in vitro
transcription by
Escherichia coli
RNA polymerase in the presence of m
7
GpppG, the transcribed RNAs are infectious for tobacco plants. A simple reconstitution procedure increases the infectivity >100 times. Unexpectedly, both the uncapped transcript and the transcript from the uncut plasmid DNA are also infectious, although their infectivities are very low. The progeny viruses multiplying in tobacco plants accurately reflect the cloned sequence. By the same method, we succeeded in the
in vitro
transcription of infectious RNA of attenuated strain L
11
A, which is phenotypically distinguishable from wild-type TMV on both tobacco and tomato plants.
Differentiation of myeloid cells is accompanied by increased levels of pp60c-src protein and kinase activity.
Authors: Gee C E , Griffin J , Sastre L , Miller L J , Springer T A , Piwnica-Worms H , Roberts T M
Published: May 2006

We have detected a significant increase in the levels of pp60c-src kinase activity associated with the differentiation of myeloid cell lines HL-60 and U-937. The induction of pp60c-src kinase activity becomes apparent approximately 14 hr after the addition of phorbol 12-myristate 13-acetate and increases 20-fold by 72 hr. The enhanced kinase activity can be accounted for by elevated levels of c-src protein in the differentiated cells. When nonleukemic bone marrow cells were examined, myeloid progenitor cells exhibited a low level of pp60c-src kinase activity. As these cells are allowed to differentiate in culture, the resulting adherent monocytes are as high in pp60c-src kinase activity as HL-60 cells induced to differentiate into monocytes. A strong correlation is found between the levels of pp60c-src kinase activity and the degree of monocytic differentiation of the cells from patients with acute myeloid leukemia. Our findings suggest that the activation of pp60c-src kinase activity is a normal physiological event associated with myeloid differentiation.