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At least 1,315 records · Page 73Linked to original sources
PubMed1987

Expression of three genes for elongation factor 1 alpha during morphogenesis of Mucor racemosus.

Three genes, TEF-1, -2, and -3, encode elongation factor 1 alpha in Mucor racemosus. Neutral and alkaline S1 nuclease analyses revealed that the genetic organization is unique for each of the genes. The number and size of the intervening sequences vary in these closely related genes, which suggests that complex genetic rearrangements gave rise to the elongation factor 1 alpha gene family. Nucleotide sequence data from restriction fragments isolated from the 5' and 3' ends of TEF-2 and -3 confirmed the presence of a second intervening sequence in these genes. These data along with S1 nuclease mapping revealed a region at the 3' end of the three genes which was predicted to be transcribed but untranslated. Unique oligonucleotides containing 19 bases were synthesized to hybridize to this unique trailer region in the elongation factor 1 alpha transcripts. These oligonucleotides were used as probes in standard Northern analysis of RNA purified from M. racemosus cells of several morphological types. It was determined that all three genes were expressed in the cell morphological types studied. However, the accumulated level of transcript derived from each gene varied considerably, with TEF-1 mRNA present in approximately twofold greater quantity than the TEF-3 transcript and up to sixfold greater quantity than TEF-2. The level of TEF-1 and -2 mRNA varied little among the cell morphological types studied, whereas TEF-3 mRNA was present in twofold greater quantity in sporangiospores than in either germlings or yeast cells which had been induced to undergo morphogenesis to hyphae. These data suggest that there is differential expression of the genes encoding elongation factor 1 alpha in M. racemosus. At least one gene, TEF-3, shows a morphology-specific pattern of transcript accumulation.

DNA, Fungal↗
PubMed1994

High level production of potyvirus-like particles in insect cells infected with recombinant baculovirus.

The full length gene for the coat protein (CP) of the potyvirus, Johnsongrass mosaic virus, was incorporated into recombinant baculovirus and expressed in insect cells. Western blot and Coomassie-stained polyacrylamide gel electrophoresis analysis of infected insect cells demonstrated that CP was produced in large quantity. Electron microscopic examination of these cells showed the presence of numerous potyvirus-like particles in the cytoplasm. Morphologically the particles resembled potyvirus particles assembled in vitro in the absence of viral RNA and those found in Escherichia coli expressing the recombinant CP gene.

Animals↗
PubMed1988

Functional mapping of an AcNPV immediately early gene which augments expression of the IE-1 trans-activated 39K gene.

An early gene which augments the expression of the delayed early/late 39K gene of the baculovirus Autographa californica nuclear polyhedrosis virus (AcNPV) was identified by functional mapping. Transient expression of the plasmid p39CAT, containing the bacterial chloramphenicol acetyltransferase coding sequences under the control of the promoter of the 39K protein, was observed in cells cotransfected with AcNPV DNA digested with several restriction endonucleases. However, when p39CAT was cotransfected with viral DNA digested with Bg/II restriction endonuclease, no CAT activity could be detected. To map the location of the Bg/II-sensitive sequences required for efficient expression of 39CAT, p39CAT and Bg/II-digested viral DNA were cotransfected with a PstI library of AcNPV DNA. The PstI-N fragment restored 39CAT activity. A major early 1.3-kb transcript from this fragment was mapped by S1 nuclease analysis. Transient assay experiments indicated that this major transcript of the PstI-N fragment was produced by an immediate early gene, named IE-N. The PstI-N fragment alone did not activate expression of p39CAT but was required when IE-1 was present in limiting quantities.

Chromosome Mapping↗
PubMed1992

On the base sequences of the promoters in transcription initiation.

The base sequence of a specific DNA region identified as the promoter is investigated by means of the quantity S(r) corresponding to "superdelocalizability" of oxygen ion of each phosphate for the ten DNA dimer units ([XY/Y'X']2-) and ([XY/Y'X']2- + H+)-complexes. A mechanism is proposed of how RNA polymerase can recognize its transcription site (phosphate), and is applied to the Escherichia coli promoters, lacUV5, recAp, rrnEpl, and rrnEp2. The result explains fairly well the character of the promoters experimentally found.

Base Sequence↗
PubMed1999

Central and peripheral expression of neurokinin-1 and neurokinin-3 receptor and substance P-encoding messenger RNAs: peripheral regulation during formalin-induced inflammation and lack of neurokinin receptor expression in primary afferent sensory neurons.

The neurokinin-1 receptor and its tachykinin neuropeptide ligand substance P are associated with the mediation of nociception. Substance P released from primary afferent sensory neurons activates neurokinin receptors on both central and peripheral targets that mediate specific aspects of central sensitization and inflammatory function; however, an autoreceptor function for the neurokinin-1 receptor remains highly controversial. Activation of the neurokinin-1 receptor by substance P during chronic nociception increases neurokinin-1 receptor gene expression in the spinal cord. Similarly, neurokinin-3 receptors on peripheral or target tissues or neurons could play an important role in the sensitization of sensory neurons. Therefore, this study (i) mapped the steady-state levels of substance P-encoding preprotachykinin, neurokinin-1 and neurokinin-3 receptor messenger RNAs in central and peripheral tissues including sensory ganglia, and (ii) investigated whether formalin-evoked nociception altered the quantity or location of neurokinin-1 or neurokinin-3 receptor messenger RNAs in the sensory ganglia or inflamed peripheral targets for substance P. Solution hybridization-nuclease protection assays quantified neurokinin receptor messenger RNA levels in central and peripheral tissues from normal and formalin-inflamed rats. High concentrations of the neurokinin-1 receptor were found in whole brain, spinal cord, and peripheral target organs innervated by substance P-containing neurons. Measurable levels of neurokinin-3 receptor messenger RNA were found only in brain, spinal cord and urinary bladder. Results also show that neither neurokinin-1 nor neurokinin-3 receptor messenger RNAs were detectable in primary afferent sensory neurons in the dorsal root ganglia of normal or formalin-inflamed rats. Neurokinin-1 receptor messenger RNA levels were, however, significantly increased in hindpaw tissues inflamed by formalin for 6 h. These results indicate that the plasticity of neurokinin-1 receptor gene expression in non-neuronal peripheral cells could regulate sensitivity to substance P in a manner similar to that in the spinal cord dorsal horn. Altered neurokinin-1 receptor gene expression provides a useful marker of long-term nociceptive activation and may mediate peripheral mechanisms of hyperalgesia and cellular sensitization during inflammation. Importantly, inflammation does not induce a phenotypic change in afferent sensory neurons providing neurokinin receptor targets for the direct sensitization of these neurons by substance P.

Animals↗
PubMed1973

Biochemical changes during growth and encystment of the cellular slime mold Polysphondylium pallidum.

The growth of the cellular slime mold, Polysphondylium pallidum, was studied on a semidefined medium in shaken suspension. When the medium contained large quantities of particulate material, growth was more rapid and the cellular size and protein content were smaller than when growth occurred on a medium containing less particulate material. The cellular levels of DNA, RNA, and protein; of lysosomal enzymes (acid phosphatase, acid proteinase); and of peroxisomal enzymes (catalase) were assayed during growth and the subsequent stationary phase that led eventually to encystment. Only DNA remained at a constant cellular level. Encystment of exponentially growing cells could also be initiated by washing them and introducing them into a soluble peptone medium. The rate of encystment was proportional to the osmolarity of this medium. The encystment process was followed with respect to the cellular levels of DNA, RNA, protein, carbohydrates, acid phosphatase, acid beta-N-Ac-glucosaminidase, and catalase. The most dramatic change occurred in the cellular cellulose content, which increased by at least an order of magnitude by the time encystment was morphologically complete. It was concluded that the encystment of this slime mold in suspension exhibits a number of biochemical similarities to the development of this and other cellular slime molds on a surface.

Acid Phosphatase↗
PubMed1985

Human tumor cell lines with EGF receptor gene amplification in the absence of aberrant sized mRNAs.

A survey of human tumor cell lines for increased PDGF or EGF receptors identified 5 lines which bind from 6 to 13 times more EGF than normal human fibroblasts. Immunoprecipitation analysis links the elevated binding activity to increased quantities of the EGF receptor protein. EGF receptor gene amplification was detected in 2 of the cell lines. No evidence for EGF receptor gene rearrangements was found at the level of DNA or RNA structure. The results suggest that elevated levels of EGF receptor can be associated with at least three distinct mechanisms. These include gene amplification accompanied by rearrangement, gene amplification without accompanied alteration of mRNA transcripts, and extensive expression without gene amplification.

Epidermal Growth Factor↗
PubMed1986

Protein products synthesized by a cloned viral protease gene.

A region of the poliovirus genome coding for a cysteine protease was expressed in E. coli. Following separation in isoelectric focussing gels, four new proteins were identified and were shown to be products of the viral cDNA. Although a majority of the protein products is aggregated, the system offers the first practical basis for production of large quantities of a viral protease.

Amino Acid Sequence↗
PubMed1987

Studies on the growth of the fetal guinea pig. Changes in the plasma concentration of sulphation-promoting activity and of insulin-like growth factors during gestation.

Plasma sulphation-promoting activity, insulin-like growth factors (IGF)-I and -II and insulin concentrations have been measured in the developing guinea. Sulphation-promoting activity fell progressively from midgestation to term in a manner that correlated fairly closely with the decline in the fractional rate of body and liver growth. The changes in plasma concentrations of IGF-I, & -II were quite different, both being substantially higher than fetal plasma insulin concentration. IGF-I, like insulin, plasma concentration rose between 35 and 50 days, then declined as term approached. These changes correlated with phases of lipid, DNA and RNA synthesis, but not of glycogen synthesis in the fetal liver. Fetal Plasma IGF-II concentration was comparatively low until about 55 days gestation then rose sharply, at the time that large quantities of glycogen are deposited in the fetal liver and myelation is initiated in the fetal brain, to achieve very high levels by 60-63 days then declining as term approaches. Plasma IGF-I and -II, measured by radioimmunoassay and radioreceptor assay respectively, showed the same cross-reactivity or binding characteristics as peptides in human or rat plasma. On separation by hplc IGF-I consisted of two major fractions and IGF-II of one. This picture was the same if the peptides were from fetal or adult plasma. There was no evidence of a distinctly fetal class of IGF. Plasma IGF-I and -II concentrations did not correlate with changes in fetal size or fractional rate of growth.

Animals↗
PubMed1995

Isolation and characterisation of a melon cDNA clone encoding phytoene synthase.

A cDNA clone (MEL5), encoding a protein homologous to phytoene synthase (PSY), has been isolated from a climacteric melon fruit cDNA library, using the tomato cDNA clone TOM5 [34] as a heterologous probe. MEL5 hybridised to a transcript of 1.65 kb which suggested that the 1.36 kb clone, isolated originally, was not full-length. The missing 5' end was isolated by a reverse transcriptase-polymerase chain reaction (RT-PCR)-based method. This enabled the full sequence of the protein to be deduced and the cleavage site of the transit peptide for chromoplast import to be predicted. Northern analysis of RNA extracted from fruit samples of different ripening stages as well as from roots, leaves and flower petals was used to examine the expression pattern of the corresponding mRNA. The corresponding mRNA. The transcript corresponding to MEL5 is present at low quantities in unripe (green) fruit, reaches its highest levels when the fruit turns from green to orange and persists at lower levels during later ripening stages. A similar transcript was also detected in flower petals and in trace amounts in leaves and roots. Genomic Southern analysis indicates that the clone is homologous to a low-copy-number gene family. Sequence analysis showed a high degree of conservation among plant PSYs.

Alkyl and Aryl Transferases↗
PubMed1998

Thioacetamide effects on the polypeptidic and nucleoporin pattern and chemical composition of rat liver nuclear envelope subfractions.

The effect of the administration of seven doses of the hepatocarcinogen thioacetamide on the chemical composition of rat liver nuclear envelope subfractions: associated chromatin, nuclear membranes and pore complex-lamina fraction, is analyzed. No alteration in DNA, RNA or phospholipid content is observed after the hepatocarcinogen treatment. Electrophoretic studies of each subfraction from thioacetamide treated rats show differences in the relative proportions of some polypeptides when compared with the controls. Examination of the wheat germ agglutinin binding polypeptides of each subfraction reveals a decrease in the stain of two pore complex-lamina nucleoporins of 85 and 164 kDa and an increase in one of 93 kDa; this observation can be due to changes in the quantity and/or in the agglutinin binding capacity of the nucleoporin as a result of thioacetamide administration. In view of the participation of nucleoporins in the nucleocytoplasmic transport, the changes observed suggest a relationship between changes of some O-linked N-acetyl glucosamine polypeptides components of the nuclear pore complex and the altered transport of some RNA species observed after thioacetamide administration.

Animals↗
PubMed1976

High-titer replication of nondefective Sendai virus in MDBK cells.

Egg-grown Sendai virus was adapted to growth in a bovine kidney cell line (MDBK cells) by serial passage under defined conditions. The adapted virus contained only 50S RNA and was highly infectious for MDBK cells. Infection of these cells with a high multiplicity of adapted virus resulted in a yield of 10(8) MDBK-infectious units/ml by 18 h, accompanied by severe cytopathic changes in the host. Cell fusion did not occur. Examination of the proteins of the adapted virus revealed that despite the high infectivity of this virus for MDBK cells the virions contained considerable quantities of Fo, the precursor to the F glycoprotein that is responsible for cell fusion and high infectivity in other systems.

Adaptation, Biological↗
PubMed1984

Lineage segregation and developmental autonomy in expression of functional muscle acetylcholinesterase mRNA in the ascidian embryo.

Acetylcholinesterase is a histospecific marker of cell differentiation occurring only in the muscle and mesenchyme tissues of the ascidian embryo. The distribution of functional mRNA coding for this enzyme has been investigated and it is shown here that only cells of muscle and mesenchyme lineages possess such a template. Blastomeres of four cell lineage quadrants were separated microsurgically from eight-cell-stage embryos of Ciona intestinalis and raised in isolation until muscle development was well advanced. Measurement of enzyme activity in the resulting partial embryos revealed that acetylcholinesterase was limited to descendants of one blastomere pair, the B4.1 blastomeres containing muscle and mesenchyme lineages. To study the tissue distribution of acetylcholinesterase mRNA, RNA from partial embryos was translated in Xenopus laevis oocytes. When oocytes were injected with an appropriate template, they synthesized a biologically active acetylcholinesterase that could be selectively immunopurified with an antiserum to the ascidian enzyme. Under the conditions used the quantity of acetylcholinesterase mRNA was directly related to the enzyme activity in immunoprecipitates. Acetylcholinesterase mRNA was found only in B4.1 lineage partial embryos where it occurred in approximately the same amount as in whole embryos of the same age. Since there is a limited period from gastrulation until the middle tail-formation stage when functional acetylcholinesterase mRNA accumulates, the results of our mRNA distribution experiments strongly suggest that the gene for ascidian acetylcholinesterase is active only in muscle and mesenchyme tissues. The histospecific occurrence of this enzyme apparently does not involve selective, cell-specific control of translation.

Acetylcholinesterase↗
PubMed2003

Only one pRNA hexamer but multiple copies of the DNA-packaging protein gp16 are needed for the motor to package bacterial virus phi29 genomic DNA.

A common feature in the maturation of linear dsDNA viruses is that the lengthy viral genome is translocated with remarkable velocity into a limited space within a preformed protein shell using ATP as motor energy. Most biomotors, such as myosin, kinesin, DNA-helicase, and RNA polymerase, contain one ATP-binding component that acts processively. An examination of the well-studied dsDNA viruses reveals that DNA packaging motors involve two nonstructural components. Which component of the motor is the integrated processive factor to turn the motor has not been identified. In bacterial virus phi 29, these two components consist of a gp16 protein and an RNA molecule called pRNA. We have previously predicted and recently confirmed that gp16 binds ATP. It is generally believed that gp16 serves as an ATP-binding and processive component to drive the motor. In this article, phi 29 DNA-packaging intermediates were purified in quantity and examined to differentiate the role between gp16 and pRNA. It was found that the pRNA hexamer is an integral motor component, while gp16 is not stably bound. Only one pRNA hexamer, but multiple copies of gp16, were needed to accomplish DNA packaging. pRNA functions continuously during the entire DNA translocation process, suggesting that pRNA is a vital part of the DNA packaging motor.

Bacillus Phages↗
PubMed1984

Assembly of transcriptionally active chromatin in Xenopus oocytes requires specific DNA binding factors.

Active minichromosomes assembled on injected 5S RNA gene clones are stable in Xenopus oocytes; endogenous 5S DNA specific factor(s) are required for their assembly. When somatic-type and oocyte-type 5S RNA gene clones are coinjected, the somatic genes are assembled into active minichromosomes, while most of the oocyte genes are assembled into inactive ones. The differential 5S RNA gene expression, which mimics that in somatic cells, appears to result from titration of 5S DNA specific factor(s) by the competing somatic 5S DNA, followed by histone mediated assembly of inactive chromatin on the oocyte 5S DNA. Stable minichromosomes are also assembled on a cloned histone H4 gene; again, intragenic DNA rearrangements affect the efficiency of assembly of active chromatin and differential gene expression occurs after coinjection of two or more H4 DNA constructs. We suggest that the H4 DNA molecules also compete for limiting quantities of specific DNA binding factor(s) required for the assembly of active H4 gene chromatin.

Animals↗
PubMed2001

Establishment of an infectious RNA transcription system for Striped jack nervous necrosis virus, the type species of the betanodaviruses.

A system has been established to produce infectious RNA transcripts for Striped jack nervous necrosis virus (SJNNV), the type species of the betanodaviruses, which infect fish. An enzymological analysis suggested that both RNA1 and RNA2 of SJNNV have a 5' cap. Both RNAs were largely resistant to 3' polyadenylation and ligation, suggesting the presence of an interfering 3' structure, while a small quantity of viral RNAs were polyadenylated in vitro. The complete 5' and 3' non-coding sequences of both segments were determined using the rapid amplification of cDNA ends method. Based on the terminal sequences obtained, RT-PCR was carried out and plasmid clones containing full-length cDNA copies of both RNAs, positioned downstream of a T7 promoter, were constructed. These plasmids were cleaved at a unique restriction site just downstream of the 3' terminus of each SJNNV sequence and were transcribed in vitro into RNA with a cap structure analogue. A mixture of the transcripts was transfected into the fish cell line E-11. Using indirect immunofluorescence staining with anti-SJNNV serum, fluorescence was observed specifically in these transfected cells; this culture supernatant exhibited pathogenicity to striped jack larvae. Northern blot analysis of E-11 cells infected with the recombinant virus or SJNNV showed small RNA (ca. 0.4 kb) that was newly synthesized and corresponded to the 3'-terminal region of RNA1. Finally, the complete nucleotide sequences of these functional cDNAs (RNA1, 3107 nt; RNA2, 1421 nt) were determined. This is the first report of betanodavirus cDNA clones from which infectious genomic RNAs can be transcribed.

3' Untranslated Regions↗
PubMed1989

Sindbis virus: an efficient, broad host range vector for gene expression in animal cells.

Sindbis virus, an enveloped virus with a single-stranded RNA genome, was engineered to express a bacterial protein, chloramphenicol acetyltransferase (CAT), in cultured insect, avian, and mammalian cells. The vectors were self-replicating and gene expression was efficient and rapid; up to 10(8) CAT polypeptides were produced per infected cell in 16 to 20 hours. CAT expression could be made temperature-sensitive by means of a derivative that incorporated a temperature-sensitive mutation in viral RNA synthesis. Vector genomic RNAs were packaged into infectious particles when Sindbis helper virus was used to supply virion structural proteins. The vector RNAs were stable to at least seven cycles of infection. The expression of CAT increased about 10(3)-fold, despite a 10(15)-fold dilution during the passaging. Sindbis virus vectors should prove useful for expressing large quantities of gene products in a variety of animal cells.

Aedes↗
PubMedDate not supplied

[Changes in the quantity of nucleic acids in the liver and kidneys of rats with experimental lead poisoning].

In the liver and kidneys of 125 control and test albino rats poisoned perorally daily with different doses of neutral lead acetate for 1, 3, 5, 10, 20, 30 and 45 days the RNA and DNA contest was measured. A statistically significant increase of nucleic acids was registered in both organs, earlier and stronger pronouced in the liver than in the kidneys. The amount of DNA changed quicker than that of DNA. In all the groups of animals the rise in the content was proportional to the introduced amount of lead (20, 40 and 100 mg/kg body weight). Following poisoning with 20 mg/kg of lead acetate the DNA and RNA accretion (statistically significant) remained after the 10th day roughly the same till the 45th day. The main reason for the DNA increment in the study organs seems to be an intensive synthesis, the rise of RNA is due to an inhibited activity of ribonuclease.

Animals↗