Region Of 3C Research Articles

CME and Ejection of Large Scale Magnetic Fields, Helical Magnetic Fields, and Intrinsically Asymmetric Jets - New Findings in AGN

AbstractThe orthodox model of active galactic nuclei (AGN), as is generally accepted, is that of Rees. We have found an AGN (3C 147) which has a counter-jet much longer than the main jet. It also has an unusual sideways ejection from the nuclear region. Both of these and the 3-jet structure per se do not seem to conform with the general accepted model, and are also not explained by relativistic beaming effects. We speculate that this is due to coronal mass ejection (CME) in the accretion disk corona. Recently, we have found convincing new evidence that this is true. We have also found direct evidence of helical magnetic fields in the core region of 3C 147. These results may be of importance to the understanding of AGN.

Detection and differentiation of Epstein–Barr virus strains byin situpolymerase chain reaction

Anin situpolymerase chain reaction (IS-PCR) technique was used to detect and differentiate strains of episomal Epstein–Barr virus (EBV) in infected cells. IS-PCR was performed on cell monolayers in eight-chamber glass slides using EBV type-specific primer pairs conserved within the EBV-encoded nuclear antigen (EBNA) 3C region. The amplicons in the cells were detected byin situhybridization using EBV type-1 and type-2 specific 5′-biotinylated oligonucleotide probes and avidin-conjugated alkaline phosphatase as secondary reagent. This method was successfully used to identify EBV strains not only in Burkitt's lymphoma cell lines but also in B cells obtained from a patient with infectious mononucleosis. The technique described in this report is a reliable method to detect latently infected EBV-positive cells and can potentially be used to identify and type EBV strains present in clinical specimens.

The nature of the broad-line region in the radio-loud active galactic nucleus 3C 390.3

We present an analysis of the ultraviolet and X-Ray variability of the Broad- Line-Radio Galaxy 3C390.3 over 15 years. The UV continuum showed large variations with amplitudes of up to a factor of 10. We find: (1) The variations of CIV and Ly_alpha are highly correlated with the UV continuum, and are delayed with respect to the continuum variations by 50-110 days with the red wing of both CIV and Ly_alpha , leading the blue wing; (2) The CIV/Ly_alpha ratio is positively correlated with both the continuum flux and UV line strength, a behavior different from other AGNs studied so far; (3) The blue sides of the Ly_alpha and CIV profiles are similar to the blue side of the Balmer lines, while the red sides are different, suggesting a different origin for the red peak in the Balmer lines. Our results suggest: (1) The broad CIV and Ly_alpha emitting gas is infalling towards the central object; (2) The overall behaviour of the CIV/Ly_alpha ratio and the absence of a big blue bump, strongly indicate the coexistence of optically thick as well as optically thin BLR clouds; (3) Assuming circular symmetry and predominantly circular motion, the BLR gas is situated at 83$\pm$25 lightdays from the central source; (4) Under these assumptions and with the derived circular velocity of $v_{rot} \simeq$ 2850 km s$^{-1}$, the central mass inside this radius is confined to $1.3~10^8 M\odot < M_{CM}< 4.0~10^8 M\odot$; (6) Comparing our results with those obtained from VLBI and observations of the Fe $K\alpha$ line, suggests the association of the BLR with a disk, inclined at 98$\pm$12 degrees with respect to the direction of superluminal motion of the radio blobs.

Study of Time Varitions of UV Continuum and Emission Lines in 3C 390.3

Based on the IUE SWP spectra obtained between 1978 and 1994, the variations of the UV continuum and the Ly-alpha and C IV emission lines of the broad-line radio galaxy 3C390.3 are studied. The UV continuum between 1220 and 1990 A has varied considerably. In 1991 August, the flux at 1360 A reached a maximum level ~27 times as high as its minimum level. At 1850 A, the continuum varies by a factor of ~12. Significant variations are frequently observed in periods as short as one month. The total flux of Ly-alpha and C IV emission varies by a factor of ~5. Their profiles are fitted with one narrow component, unresolved at the instrumental resolution of FWHM ~2000 km/s, and three broad components (FWHM ~6000 km/s). The narrow component varies by a factor of ~2.5. The broad components on the blue and red wings of the Ly-alpha and C IV emission profile, which correspond to the double humps in the H-alpha and H-beta emission feature, display a close correlation to the varying continuum, with a time lag of ~45 days. The blue Ly-alpha component has been stronger than the red component except for several epochs in 1980 and 1991. The C IV/Ly-alpha flux ratio is ~0.4 for the narrow component. For the broad components, this ratio varies considerably around an average value of unity. In 1991 March, the blue Ly-alpha component was stronger than the red, while for C IV the red component was stronger. Such differential variations do not match the accretion disk characteristics. The findings suggest that the narrow- and broad-line region in 3C 390.3 may be associated with a radio jet.

Sequence and Structural Determinants of the Interaction between the 5′-Noncoding Region of Picornavirus RNA and Rhinovirus Protease 3C

It has previously been established that human rhinovirus 14 protease 3C binds specifically to the 5'-noncoding region of the viral RNA. A series of mutants of protease 3C and deletion or point mutants of the 5'-noncoding region of the viral RNA were analyzed to elucidate the sites of interaction between the protease and the RNA. Amino acids in protease 3C essential for RNA binding were found to be discontinuous in the amino acid sequence, and mutations which destroyed RNA binding did not affect the catalytic (proteolytic) activity of protease 3C. Based on the three-dimensional structure of rhinovirus 14 protease 3C, the RNA binding region is located in an extended area distinct from the catalytic triad. A single stem-loop structure of 27 nucleotides (stem-loop d) in the 5'-noncoding region was necessary and sufficient to bind protease 3C. Mutagenesis of either the base-paired stem or unpaired loop or bulge regions of stem-loop d suggested that the base-paired stem, but not the loop or bulge, carries important determinants of protease 3C binding. This conclusion is strengthened by the observation that rhinovirus 14 protease 3C bound specifically to the 5'-noncoding region of poliovirus RNA, and only the base-paired stem of stem-loop d is conserved between poliovirus and rhinovirus RNAs.

Identification of Four Different Forms of Syntaxin 3

cDNAs for four different forms of syntaxin 3 were cloned from a mouse brain cDNA library, and the proteins encoded by these clones were named syntaxin 3A (previous syntaxin 3), 3B, 3C and 3D. Syntaxin 3B contained a different sequence in the carboxyl teminal region from that of syntaxin 3A. The amino terminal region of syntaxin 3C contained an 18 amino acid sequence instead of a 34 amino acid sequence present in syntaxins 3A and 3B. Syntaxin 3D consisted of only 86 amino acids and lacked any putative transmembrane segments. These forms of syntaxin 3 are probably generated by alternative splicing of the primary transcript of syntaxin 3 gene. Cytoplasmic portions of syntaxins 3A and 3B but not of syntaxin 3C or 3D bound to Munc-18/n-sec1.

Proteinase 3C of Hepatitis A Virus (HAV) Cleaves the HAV Polyprotein P2-P3 at All Sites Including VP1/2A and 2A/2B

Thus far, the only virus-encoded proteinase of hepatitis A virus (HAV) detected is 3C, which was shown to catalyze proteolysis of most of the suggested cleavage sites within the HAV precursor polyprotein. To elucidate whether or not HAV proteinase 3C and its precursors are involved in processing of the yet unidentified sites in the polyprotein P2-P3, the genomic region of 3C including flanking sequences were expressed in a bacterial system and by cell-free translation. In both systems 2A-reactive proteins of 10 (2A) and 16 kDa (ΔVP1-2A) were processing products of a polyprotein representing ΔVP1-P2-P3* (Δ and * denote N- or C-terminally truncated proteins, respectively), thus providing evidence for cleavage at sites VP1/2A and 2A/2B by proteinase 3C. In the cell-free expression system, processing at the P2/P3 junction was rapid and complete, whereas sites 3A/3B, 3B/3C, and 3C/3D were inefficiently cleaved, as evidenced by the accumulation of the stable precursor polypeptides P3* and 3ABC. In contrast to the eukaryotic system, mature 3C was produced in Escherichia coli. Intermolecular cleavage by recombinant 3C occurred at all putative sites within the proteolytically inactive polyprotein P2-P3*μ. The results of this study indicate that protainasa 3C mediates the primary as well as the secondary cleavages of the HAV polyprotein and thus shows an activity profile broader than that of 3C proteinases of other picornaviruses.

Penetration depth and Ginzburg number in Rb 3C 60

The penetration depth λ, the Ginzburg-Landau parameter κ and the Ginzburg number Gi in the superconducting fulleride Rb 3C 60 are estimated. To determine these quantities the results of recent magnetization measurements performed by Politis et al. on the fine powder specimen are analyzed. A finiteness of superconducting grain sizes is taken into account and shown to influence considerably the calculated values of λ and κ. The experimental data are found to be consistent with the assumption that λ( T) obeys the Ginzburg-Landau theory within the whole temperature range studied and result in λ(0)=2100 Å, κ ≈90. The estimated critical region in Rb 3C 60 turns out to be narrow enough, Gi ≈10 -4, indicating that superconducting fluctuations in fullerides are weaker than in high- T c oxide superconductors.

Very Wide “Visual Double Stars” for the Astrometric Calibration of CCD’s

AbstractWe present first results of a catalogue of standard double stars for the astrometric calibration of CCD’s. The data were taken from photographically determined precise positions and proper motions of stars in the region of radio sources and open clusters. In this report, we give preliminary results of stars in the region of 3C 273 and NGC 1647.

Poliovirus proteinase 3C converts an active form of transcription factor IIIC to an inactive form: a mechanism for inhibition of host cell polymerase III transcription by poliovirus.

In HeLa cells, RNA polymerase III (pol III)-mediated transcription is severely inhibited by poliovirus infection. This is due primarily to a reduction in the transcriptional activity of TFIIIC, a transcription factor which binds in a sequence specific manner to the internal promoter of pol III genes. Using gel retardation assays, we have shown previously that inhibition of pol III transcription by poliovirus is correlated with disappearance of a transcriptionally active form of TFIIIC (complex I) concomitant with the appearance of a faster mobility, transcriptionally inactive form of TFIIIC (complex III). We show here that a poliovirus with a point mutation in the proteinase 3C (3Cpro) region failed to produce complex III and is limited in its ability to inhibit pol III transcription compared with the wild-type virus. Incubation of purified 3Cpro, expressed in Escherichia coli, with transcriptionally active TFIIIC (complex I) in vitro resulted in generation of the transcriptionally inactive complex III form of TFIIIC. In an in vitro transcription assay, treatment of the complex I form of TFIIIC with 3Cpro almost completely inhibited pol III transcription. Finally expression of the 3Cpro gene in transfected HeLa cells resulted in significant inhibition of pol III-mediated transcription. The results presented here suggest that proteolysis of the transcriptionally active form of TFIIIC by poliovirus 3Cpro is a mechanism by which poliovirus inhibits host cell RNA pol III transcription.

Controlled growth of 3C-SiC and 6H-SiC films on low-tilt-angle vicinal (0001) 6H-SiC wafers

We have found that, with proper pregrowth surface treatment, 6H-SiC single-crystal films can be grown by chemical vapor deposition (CVD) at 1450 °C on vicinal (0001) 6H-SiC with tilt angles as small as 0.1°. Previously, tilt angles of greater than 1.5° were required to achieve 6H on 6H at this growth temperature. In addition, 3C-SiC could be induced to grow within selected regions on the 6H substrate. The 3C regions contained few (or zero) double-positioning boundaries and a low density of stacking faults. A new growth model is proposed to explain the control of SiC polytype in this epitaxial film growth process.

Application of oxidation to the structural characterization of SiC epitaxial films

Both 3C-SiC and 6H-SiC single-crystal films can be grown on vicinal (0001) 6H-SiC wafers. We have found that oxidation can be a powerful diagnostic process for (1) ‘‘color mapping’’ the 3C and 6H regions of these films, (2) decorating stacking faults in the films, (3) enhancing the decoration of double positioning boundaries, and (4) decorating polishing damage. Contrary to previously published oxidation results, proper oxidation conditions can yield interference colors that provide a definitive map of the polytype distribution for both the Si face and C face of SiC films. Defects were more effectively decorated by oxidation on the Si face than on the C face.

Line emission from another relativistic accretion disk - 3C 332

Observational and theoretical investigations are reviving interest in the hypothesis that the broad emission lines in some active galactic nuclei (AGNs) might arise in a relativistic accretion disk. But until now only one object, Arp 102B, has displayed the distinctive double-peaked, asymmetric line shape which is fitted well by the disk model. This Letter reports the discovery of a line profile in a second radio galaxy, 3C 332 (z = 0.1511), which is so similar to that of Arp 102B as to suggest the existence of a small but distinct class of objects in which the broad emission lines arise largely in the disk. In the context of the model, the line-emitting region in 3C 332 lies between r_1_ ~ 175 and r_2_ 525r_g_. In comparison, the line profile of Arp 102B is fitted with r_1_ ~ 350 and r_2_~ 1000. All aspects of the model developed for Arp 102B are consistent with the properties of 3C 332.

Cleavage of small peptides in vitro by human rhinovirus 14 3C protease expressed in Escherichia coli

The 3C region of human rhinovirus 14 was expressed in Escherichia coli. The microbially synthesized protease was functional, since the expressed precursor underwent autoproteolytic processing to generate mature molecules of the expected molecular weight and antigenicity. Mutation of the putative active-site Cys-146 residue to an alanine resulted in the synthesis of unprocessed precursor molecules. Large quantities of the 20-kilodalton protease were purified by a simple purification protocol, and the resulting molecule was shown to be biologically active in vitro against synthetic peptides corresponding to the 2C-3A cleavage site. This site was cleaved with high efficiency and fidelity and was used to generate kinetic data on the 3C protease. The protease exhibited sensitivity to Zn2+, was capable of cleaving five of seven rhinovirus cleavage site peptides tested with variable efficiency, and could distinguish authentic substrate peptides from control peptides containing the dipeptide cleavage sequence pair Gln-Gly.

Human rhinovirus 3C protease: cloning and expression of an active form in Escherichia coli.

A cDNA encoding the viral protease from the 3C region of human rhinovirus type 14 was expressed in Escherichia coli through the use of a periplasmic secretion vector. The recombinant protease contained an eight amino acid N-terminal extension that enabled its detection by a specific antibody. It was expressed at a level of approximately 1 mg/L of E. coli culture. Biological activity of the protease was assessed in vitro by using a chemically synthesized peptide consisting of a consensus picornavirus protease cleavage site, Arg-Ala-Glu-Leu-Gln-Gly-Pro-Tyr-Asp-Glu. The peptide was cleaved by the recombinant protease at the Gln-Gly bond, generating the product peptides Arg-Ala-Glu-Leu-Gln and Gly-Pro-Tyr-Asp-Glu, which could be separated from the substrate peptide by reversed-phase HPLC. An in vitro assay for the rhinovirus 3C protease was developed by observing the rate of disappearance of the substrate peak from chromatograms of the supernatants of digestion mixtures.

The Fading of the Narrow-Line Region in 3C 390.3: Erratum

The Fading of the Narrow-Line Region in 3C 390.3: Erratum

Poliovirus protein 3CD is the active protease for processing of the precursor protein P1 in vitro.

A transcription/translation system for generating poliovirus proteins in vitro has been used to assess the proteolytic activity of various polypeptides containing the virus-coded 3C region towards the poliovirus precursor protein P1. Plasmids containing a phage T7 promoter followed by either the complete poliovirus P1 sequence or various sequences containing the 3C region were used for this purpose. We showed that all except one of the 3C-containing polypeptides had a very restricted activity towards P1, generating only a small amount of VP1 and no VP0 or VP3. The only polypeptide capable of fully processing P1 into VP0, VP3 and VP1 in vitro was protein 3CD, consisting of the complete 3C and 3D sequences.

Characterization and sequence of follicle cell genes selectively expressed during vitelline membrane formation in Drosophila

To isolate genes involved in vitelline membrane production, an ovarian cDNA library was screened with eggchamber RNAs labeled in vivo. Two cDNA clones encoding RNAs that are selectively expressed in follicle cells during the period of vitelline membrane formation were isolated. Following isolation of homologous genomic clones from a Drosophila library, one gene was localized by in situ hybridization to chromosomal region 26A, and the other to 3C. Developmental Northern blots demonstrated that both genes produce 700–800 nucleotide transcripts that accumulate during the stages of vitelline membrane synthesis. In vitro translation products from hybrid selected RNAs and DNA sequence analysis both indicate that the 26A region gene encodes a major protein component of the vitelline membrane. The structural properties of the 3C region follicle cell gene seem more compatible with an intracellular function.

The fading of the narrow-line region in 3C 390.3

IUE spectra of 3C 390.3 obtained at 17 different epochs from 1978 to 1986 show that the flux in the narrow core of the Ly-alpha 1216 A and C IV 1550 A emission lines steadily declined by a factor of 1.7 and 3.2, respectively. Lloyd's optical monitoring reported in 1984 shows that the continuum intensity decreased by 2 mag over the years 1968-1980. Together, the UV and optical light curves form the strongest evidence to date that the NLR is photoionized and reverberates the continuum flux. Moreover, an upper limit of 10 lt-yr can be set for the size of the narrow line region (NLR) in this radio galaxy. The gas density is also unusual, and probably reaches 10 to the 7th/cu cm, at least in the inner part of the NLR. The broad-line gas, on the other hand, lies at only 10 to the 17th cm from the source of continuum and responds almost immediately to a change of its intensity. 25 references.

Site-directed mutagenesis of proteinase 3C results in a poliovirus deficient in synthesis of viral RNA polymerase.

We used a synthetic double-stranded oligonucleotide to introduce amino acid substitutions into the proteinase 3C region of a poliovirus type 1 cDNA clone. The six different mutant viruses recovered exhibited a small-plaque phenotype when assayed on HeLa cells. Further investigation revealed that all the mutations (with the exception of one) yielded P3 region proteins that displayed altered mobility in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. A conservative Val----Ala change at amino acid 54 of the proteinase resulted in a virus that was deficient in the production of the mature viral RNA polymerase 3D. Although this mutant achieved less than one-half of the wild-type levels of RNA synthesis during the course of infection, it still grew to nearly wild-type titers.