9,266 research outputs found
Application of the parametrical surface-wave prediction model to rapidly varying wind fields during JONSWAP 1973
The capability of a parametrical surface wave model to predict the sea state on a small array for highly variable wind fields is shown for three examples. The model treats the wind sea, for which the nonlinear interaction is most effective, in a parametrical sense. The swell is propagated along characteristics, and the source function for the swell is assumed to be zero. The model output is compared with wave measure- ments from the JONSWAP 73 experimen
The evolution of the jet from Herbig Ae star HD 163296 from 1999 to 2011
Young A and B stars, the so-called Herbig Ae/Be stars (HAeBe), are surrounded
by an active accretion disk and drive outflows. We study the jet HH 409, which
is launched from the HAeBe star HD 163296, using new and archival observations
from Chandra and HST/STIS. In X-rays we can show that the central source is not
significantly extended. The approaching jet, but not the counter-jet, is
detected in Ly alpha. In addition, there is red-shifted Ly alpha emission
extended in the same direction as the jet, that is also absent in the
counter-jet. We can rule out an accretion or disk-wind origin for this feature.
In the optical we find the knots B and B2 in the counter-jet. Knot B has been
observed previously, so we can derive its proper motion of 0.37+-0.01
arcsec/yr. Its electron density is 3000/cm^3, thus the cooling time scale is a
few months only, so the knot needs to be reheated continuously. The shock speed
derived from models of H alpha and forbidden emission lines (FELs) decreased
from 50 km/s in 1999 to 30 km/s in 2011 because the shock front loses energy as
it travels along the jet. Knot B2 is observed at a similar position in 2011 as
knot B was in 1999, but shows a lower ionization fraction and higher mass loss
rate, proving variations in the jet launching conditions.Comment: 14 pages, 8 figures, accepted by A&
Temporal regulation of murine cytomegalovirus transcription and mapping of viral RNA synthesized at immediate early times after infection
The replication of murine cytomegalovirus strain Smith in murine embryonic fibroblasts was investigated at immediate early, early, and late times after infection. Cloned subgenomic HindIII fragments of murine cytomegalovirus DNA served to define the regions of transcription. At immediate early times viral RNA classes ranging in size from 5.1 to 1.05 kilobases (kb) were transcribed mainly from the fragments HindIII-K and -L, whereas low levels of transcription were detected from the two termini HindIII-E and HindIII-N. A characteristic pattern of proteins could be translated from immediate early RNA in vitro. At early and late times after infection transcription from all HindIII fragments occurred, but different patterns of transcripts and proteins could be identified. Inhibitors of DNA synthesis induced differences in the late transcription pattern, located in the HindIII-F fragment. The coding region for abundant immediate early transcription could be located at between 0.769 and 0.817 map units. A plasmic clone containing the main part (0.769 to 0.815 map units) of this region was constructed. This region coded for six polyadenylated immediate early RNA species of 5.1, 2.75, 2.0, 1.75, 1.65, and 1.05 kb in size. Only the 1.75-kb RNA originated entirely from the HindIII-L fragment. The 5.1- and 2.75-kb RNA species were encoded by both the HindIII-L and HindIII-K fragments, and the 2.0-, 1.65-, and 1.05-kb RNA species were entirely transcribed within HindIII-K
The cytolytic T lymphocyte response to the murine cytomegalovirus
Limiting dilution (LD) analysis with two modifications, the expansion and the restimulation LD assay, led to the detection and quantification of two distinct in vivo maturation stages within the lineage of virus- specific self-restricted CTL after infection of mice with the murine cytomegalovirus (MCMV). A low frequency set, representing an average of 15% of the specifically activated CTL-P in a draining lymph node, generated virus-specific lytic activity in the absence of antigen, solely under expansion conditions provided by growth and differentiation interleukins. These cells were considered to be active and were denoted antigen-independent or interleukin-receptive CTL-P (IL- CTL-P). A high frequency set required additional antigen in vitro to generate functionally active clones, and therefore the cells were termed antigen-dependent. Both sets are present in vivo simultaneously at the peak of the acute immune response and represent antigen- activated cells because their existence strictly depends on a preceding priming event. IL-CTL-P disappear quickly after acute infection and are absent during the memory state. It is proposed that the isolation of IL- CTL-P could serve to detect viral antigen expression during persistent and/or recurrent herpes virus infections
Location, transcripts, and translation products
Cloned genomic fragments from the region (0.769 to 0.818 map units) coding for immediate-early (IE) transcripts of murine cytomegalovirus (MCMV) were used to analyze the physical organization of this region, the direction of transcription, and the proteins synthesized in vitro. Three IE transcription units could be identified. From IE coding region 1 (ie1; 0.781 to 0.796 map units) a dominant 2.75-kilobase (kb) RNA was transcribed from right to left on the prototype arrangement of the MCMV genome which directed the synthesis of an 89,000-molecular-weight polypeptide (89K polypeptide), the major IE protein. This phosphoprotein (pp89) has been shown to be active in the regulation of transcription. Upstream of ie1 and separated by the MCMV enhancer sequence was a second IE coding region, ie2, which was mapped at 0.803 to 0.817 map units. From ie2 a 1.75-kb RNA of moderate abundance was transcribed in the direction opposite to that of the ie1 RNA. After hybrid selection of the ie2 transcript, a 43,000-molecular-weight translation product was detected. A third coding region, ie3, was located directly downstream of ie1 (0.773 to 0.781 map units). The series of RNAs with low abundance, terminating in ie3, probably used the ie1 transcription start site and ranged from 1.0 to 5.1 kb in size. The 5.1-kb RNA apparently represents the nonspliced transcript from both coding regions ie1 and ie3. A 15K polypeptide was translated in vitro from RNA that was hybrid selected by ie3 sequences. Immunoprecipitation with monoclonal antibody revealed that 31K to 67K polypeptides were related to pp89. Some of these proteins were translated from RNAs that were smaller than 2.75 kb. Polypeptides related to pp89 were also synthesized in vivo. Because polypeptides unrelated to pp89 that were translated from RNA that was selected by ie2 and ie3 sequences were not immunoprecipitated by murine antisera, we assumed that the amount of these proteins synthesized in vivo during infection was probably very lo
Gene Structure, cDNA Sequence, and mRNA Distribution
The rat HNF-3 (hepatocyte nuclear factor 3) gene family encodes three transcription factors known to be important in the regulation of gene expression in liver and lung. We have cloned and characterized the mouse genes and cDNAs for HNF-3α, β, and γ and analyzed their expression patterns in various adult tissues and mouse embryonic stages. The HNF-3 proteins are highly conserved between mouse and rat, with the exception of the amino terminus of HNF-3γ, which in mouse is more similar to those of HNF-3α and β than to the amino termini of the rat HNF-3γ protein. The mouse HNF-3 genes are small and contain only two or three (HNF-3β) exons with conserved intron-exon boundaries. The proximal promoter of the mouse HNF3β gene is remarkably similar to that of the previously cloned rat HNF-3β gene, but is different from the promoters of the HNF-3α and γ genes. The mRNA distribution of the mouse HNF-3 genes was analyzed by quantitative RNase protection with gene-specific probes. While HNF-3α and β are restricted mainly to endoderm-derived tissues (lung, liver, stomach, and small intestine), HNF-3γ is more extensively expressed, being present additionally in ovary, testis, heart, and adipose tissue, but missing from lung. Transcripts for HNF-3β and α are detected most abundantly in midgestation embryos (Day 9.5), while HNF-3γ expression peaks around Day 15.5 of gestation
Characterization of the murine cytomegalovirus genes encoding the major DNA binding protein and the ICP18.5 homolog
In several herpesviruses the genes for the major DNA binding protein (MDBP), a putative assembly protein, the
glycoprotein B (gB), and the viral DNA polymerase (pol) coliocate. In murine cytomegalovirus (MCMV), two members
of this gene block, pol (Elliott, Clark, Jaquish, and Spector, 1991, Virology 185, 169-186) and gB (Rapp, Messerle,
BOhler, Tannheimer, Keil, and Koszinowski, 1992, J. Virol., 66,4399-4406) have been characterized. Here the two other
MCMV genes are characterized, the gene encoding the MDBP and the ICP18.5 homolog encoding a putative
assembly protein. Like in human cytomegalovirus (HCMV) the genes order is pol, gB, ICP18.5, and MDBP. The 4.2-kb
MDBP mRNA is expressed first in the early phase, whereas the 3.0-kb ICP18.5 mRNA is a late transcript. The open
reading frame of the MDBP gene has the capacity of encoding a protein of 1191 amino acids with a predicted molecular
mass of 131.7 kDa. The MCMV ICP18.5 ORF is translated into a polypeptide of 798 amino acids with a calculated
molecular mass of 89.1 kDa. Comparison of the amino acid sequences of the predicted proteins of MCMV with the
respective proteins of HCMV, Epstein-Barr virus (EBV), and herpes simplex virus type-1 (HSV-1) reveals a striking
homology ranging from 72% (HCMV), 50% (EBV), to 45% (HSV-1) for the MDBP sequence and from 74% (HCMV), 51 %
(EBV), to 49% (HSV-1) for the ICP18.5 sequence. These results establish the elose relationship of the two cytomegaloviruses,
and underline the usefulness of the murine model for studies on the biology of the CMV infection
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