Copper and the ACE1 regulatory protein reversibly induce yeast metallothionein gene transcription in a mouse extract

We describe a cell-free system in which the transcription of the yeast metallothionein gene is inducible by the addition of metal ions plus a specific regulatory protein. Efficient transcription requires the complete yeast ACE1 metalloregulatory protein, including both its DNA-binding and transactivation domains; a mouse nuclear extract providing RNA polymerase and general transcription factors; a template containing the ACE1 binding site; and Cu(I). Because the binding of ACE1 to DNA is dependent on Cu, it is possible to inhibit transcription by the use of Cu-complexing agents such as CN-. We have used this specific inhibition to show that the ACE1 regulatory protein is required for the maintenance as well as the formation of a functional preinitiation complex. The ability to reversibly induce yeast metallothionein gene transcription in vitro provides a powerful system for determining the molecular mechanism of a simple eukaryotic regulatory circuit.

Replication-defective vectors of reticuloendotheliosis virus transduce exogenous genes into somatic stem cells of the unincubated chicken embryo

Replication-defective vectors derived from reticuloendotheliosis virus were used to transduce exogenous genes into early somatic stem cells of the chicken embryo. One of these vectors transduced and expressed the chicken growth hormone coding sequence. The helper cell line, C3, was used to generate stocks of vector containing about 10(4) transducing units per ml. Injection of 5- to 20-microliters volumes of vector directly beneath the blastoderm of unincubated chicken embryos led to infection of somatic stem cells. Infected embryos and adults contained unrearranged integrated proviral DNAs. Embryos expressed the transduced chicken growth hormone gene and contained high levels of serum growth hormone. Blood, brain, muscle, testis, and semen contained from individuals injected as embryos contained vector DNA. Replication-defective vectors of the reticuloendotheliosis virus transduced exogenous genes into chicken embryonic stem cells in vivo.

Motion sickness and gastric myoelectric activity as a function of speed of rotation of a circular vection drum

Motion sickness symptoms and electrogastrograms (EGGs) were obtained from 60 healthy subjects while they viewed an optokinetic drum rotated at one of four speeds: 15, 30, 60 or 90 degrees.s-1. All subjects experienced vection, illusory self-motion. Motion sickness symptoms increased as drum speed increased up to 60 degrees.s-1; i.e., symptoms decreased at 90 degrees.s-1. Power, spectral intensity, of the EGG at the tachygastria frequencies (4-9 cpm) was calculated at each drum rotation speed since previous studies have shown a close correspondence between development of tachygastrias and motion sickness symptoms. Power at 4-9 cpm increased as a function of drum speed up to 60 degrees.s-1 and then decreased at 90 degrees.s-1. Power at 4-9 cpm and 60 degrees.s-1 was significantly greater than at 15 degrees.s-1. The correlation between the motion sickness symptoms and the power at 4-9 cpm was significant. Thus, drum rotation speed influenced the spectral power of the EGG at 4-9 cpm, tachygastria, and the intensity of motion sickness symptoms.

Germline transmission of exogenous genes in the chicken

Difficulties associated with in vitro manipulation and culture of the early chicken embryo have restricted generation of transgenic chickens to approaches that use replication-competent retroviruses. The need to produce transgenic chickens in the absence of replicating virus prompted development of a new method of gene transfer into the chicken. Microinjection of the replication-defective reticuloendotheliosis virus (REV) vector ME111 beneath unincubated chicken embryo blastoderms results in infection of germline stem cells. This vector contains genetic information exogenous to the chicken genome, including both the herpes simplex virus type 1 thymidine kinase gene and the Tn5 neomycin phosphotransferase gene. About 8 percent of male birds hatched from injected embryos contained vector DNA in their semen. All four positive males tested passed vector sequences onto their progeny. Analysis of G1 offspring showed that gonads of G0 male birds were mosaic with respect to insertion of vector provirus. Thus, primordial germ cells present in the unincubated chicken embryo blastoderm are susceptible to infection by defective REV vectors.

Copper activates metallothionein gene transcription by altering the conformation of a specific DNA binding protein

Copper homeostasis in yeast involves a copper binding protein, metallothionein, and a trans-acting regulatory protein that activates transcription of the metallothionein gene in response to copper ions. We show that the regulatory protein specifically binds to the metallothionein gene control sequences in the presence, but not in the absence, of copper. Both the DNA binding and metalloregulatory functions of the transacting factor are contained within its aminoterminal domain, and partial proteolysis experiments show that copper activates this domain by causing a major switch in its conformation. Silver also activates the DNA binding domain in vitro and induces metallothionein gene transcription in vivo. We propose a novel copper cluster model for the DNA binding domain based on its surprising structural similarities to metallothionein itself.

[Approaches in computer-assisted surgical planning in hip dislocation]

From a sequence of planar CT pictures of the hip joint the diagnostically relevant contours are extracted on a graphic monitor by means of an image-analysis process. To do this an image preprocessing is necessary to improve the quality of the CT pictures. These contour data permit a mathematical surface model of the hip joint to be derived using well-known methods of simulating an osteotomy. Three-dimensional reconstruction of the cartilage surface by MRI will be possible in the future. It will then be possible to plan computer-aided osteotomies with high accuracy.

Generation of competent virus in the REV helper cell line C3

We have studied the generation of replication-competent virus in cultures of the helper cell line C3, which harbors a packaging-defective provirus derived from reticuloendotheliosis virus. We transfected the C3 line with a defective provirus encoding the chicken growth hormone gene and carrying the HSV-1 tk gene. The appearance of competent virus was assayed by infection of Spafas C/E CEF, monitoring reverse transcriptase activity, and rescue of the TKTU assayed on BRLtk- cells. Our results indicate that cultures of C3 producing TKTU can release viruses which have variable growth characteristics and which can remain latent in culture for extended periods of time.

Replication-defective chimeric helper proviruses and factors affecting generation of competent virus: expression of Moloney murine leukemia virus structural genes via the metallothionein promoter

Two chimeric helper proviruses were derived from the provirus of the ecotropic Moloney murine leukemia virus by replacing the 5'long terminal repeat and adjacent proviral sequences with the mouse metallothionein I promoter. One of these chimeric proviruses was designed to express the gag-pol genes of the virus, whereas the other was designed to express only the env gene. When transfected into NIH 3T3 cells, these helper proviruses failed to generate competent virus but did express Zn2+-inducible trans-acting viral functions needed to assemble infectious vectors. One helper cell line (clone 32) supported vector assembly at levels comparable to those supported by the Psi-2 and PA317 cell lines transfected with the same vector. Defective proviruses which carry the neomycin phosphotransferase gene and which lack overlapping sequence homology with the 5' end of the chimeric helper proviruses could be transfected into the helper cell line without generation of replication-competent virus. Mass cultures of transfected helper cells produced titers of about 10(4) G418r CFU/ml, whereas individual clones produced titers between 0 and 2.6 X 10(4) CFU/ml. In contrast, defective proviruses which share homologous overlapping viral sequences with the 5' end of the chimeric helper proviruses readily generated infectious virus when transfected into the helper cell line. The deletion of multiple cis-acting functions from the helper provirus and elimination of sequence homology overlapping at the 5' ends of helper and vector proviruses both contribute to the increased genetic stability of this system.

[CT image analysis for surface reconstruction of the hip joint]

From a sequence of planar CT-pictures of the hip joint the diagnostically relevant contours are extracted on a graphic monitor by means of an image analysis process. To enable this an image-preprocessing has been needed to improve quality of the CT-pictures. From theses contour data, a mathematical surface model of the hip joint will be derived with well-known methods to simulate osteotomy.

Studies of TGEV spike protein gp195 expressed in E. coli and by a TGE-vaccinia virus recombinant

The gene coding for the surface spike protein gp195 of TGEV has been cloned and expressed in E. coli in the form of fusion proteins. These proteins were isolated and used to immunize laboratory animals. All animals developed antibodies cross-reacting with the TGEV virion but failed to neutralize the virus. The entire gp195 gene was also inserted into vaccinia to generate a TGEV-vaccinia recombinant virus (vTGE) that expressed TGEV gp195. Animals vaccinated with vTGE produced neutralizing antibodies against both TGEV and vaccinia. These results suggest the potential use of the recombinant vTGE as a vaccine against TGEV infection.

Acute hepatitis A infection in hepatitis B chimpanzee carriers

Two hepatitis B virus carrier chimpanzees which were superinfected with hepatitis A virus developed acute hepatitis followed by the production of antibodies to hepatitis A virus. The Southern blot technique employed to monitor liver hepatitis B virus DNA revealed that the amount of viral DNA in both animals was significantly reduced during the acute phase of hepatitis A infection. The levels of plasma hepatitis B DNA polymerase activity were also reduced in one chimpanzee. The high titers of HBsAg in the circulation remained unchanged throughout the study, and antibodies to the surface antigen and to e antigen were not detected. The morphological lesions in the liver were severe in one chimpanzee from whom one specimen showed both periportal focal necrosis and zonal parenchymal necrosis.

Effects of morphine on ionic currents in frog node of Ranvier

The effects of externally or internally applied morphine hydrochloride on the node of Ranvier of the frog were studied under current and voltage clamp conditions. Externally applied morphine in a concentration of 0.5-1 mM prolonged the action potential and the absolute refractory period. It inhibited the repetitive response of sensory fibres to long-lasting depolarizing pulses. Externally applied morphine was more effective in depressing the steady state K current than the peak Na current. When added to the internal medium (by diffusion from the cut ends of the fibre) morphine had a stronger effect on the peak Na current. Morphine did not alter the kinetics of Na activation but increased the time constants of development or removal of Na inactivation by a factor of about 1.2. Morphine reduced both the fast and slow phase of the inward K tail currents recorded in Ringer with 30 mM K. Of the two components (gKf1 and gKf2) of fast K conductance described by J.M. Dubois (1981, J. Physiol. 318, 297) only gKf2 was affected. The morphine antagonist naloxone in a concentration of 0.1 mM completely and reversibly abolished the component gKf2 of the fast K conductance. Naloxone did not antagonize the effect of morphine. These findings show that there are no specific opiate receptors in the membrane of peripheral nerves.

Non-A, non-B hepatitis in persistent carriers of hepatitis B virus

There are reports in the literature that infection with hepatitis A virus in hepatitis B carriers can result in resolution of the carrier state. In an attempt to induce clearance of the carrier state of hepatitis B virus in two persistently infected chimpanzees, the chimpanzees were infused with documented non-A, non-B infectious material. Biochemical and histopathological evidence of hepatitis was accompanied by the unique abnormalities of endoplasmic reticulum associated with non-A, non-B hepatitis in the chimpanzees. Elevation of alanine aminotransferase was accompanied by fourfold reduction in one chimpanzee and sixfold reduction in the other in the plasma levels of HBV-associated DNA polymerase activity and simultaneously by twofold reduction in the concentration of hepatitis B surface antigen in both chimpanzees. A mediator may account for these changes in markers of hepatitis B virus infection, and this mechanism may also explain the occurrence of spontaneous regression in some persistently infected carriers. The significance of transient red cell anaemia in non-A, non-B hepatitis, which was observed in one of the chimpanzees, is yet to be established.

Structure of 50 to 70S RNA from Moloney sarcoma viruses

The 50 to 70S RNAs of two clonal isolates of defective Moloney sarcoma-leukemia helper virus complex were analyzed by gel electrophoresis and electron microscopy. The RNAs extracted from both clone 3 and clone 124-5R of Moloney sarcoma-leukemia virus complex contained some large monomer subunits ca. 10,000 nucleotides in length (10 kilobases), which are believed to be the Moloney leukemia virus subunits. Both RNAs had an excess of a smaller, sarcoma-specific subunit, 5 kilobases (clone 3) or 6 kilobases (clone 124-5R) in length. Electron microscopy of intact 50 to 70S dimer RNA molecules showed for both clones many dimers of two small subunits, some dimers of two large subunits, but few if any heterodimers with one large and one small subunit. This result was unexpected because the sequences near the 5'end of the RNA subunits, which are believed to be involved in the dimer linkage, are probably homologous between the large and small subunits. We also observed that some small-small dimers migrated anomalously slowly on nondenaturing gels. The nature of this slow-migrating complex is unkown; it could be a higher aggregate of the small-small dimer with additional small or large subunits, or it could be an extended conformation of the small-small dimer.

Murine cytomegalovirus infection of epithelial cells in mouse tracheal ring organ culture

A differentiated tissue model was used to study the course of cytomegalovirus infection in respiratory epithelium in vitro. Mouse tracheal rings in organ culture were infected with murine cytomegalovirus. Infectious virus in the medium reached average titers of 10(5.5) plaque-forming units/ml by day 17. Infected epithelial cells on the rings contained viral antigen as demonstrated by immunofluorescence staining; light microscopy of these cells revealed enlarged nuclei, cytoplasmic vacuolization, and nuclear and cytoplasmic inclusions characteristic of infection with cytomegalo-virus. Development of viral particles, as visualized by electron microscopy, was similar to that observed in other types of cells.

Heteroduplex study of the sequence relations between RD-114 and baboon viral RNAs

The regions of sequence homology and nonhomology between the RNA genomes of RD-114 and baboon endogenous type C viruses have been mapped by an electron microscope heteroduplex study. Short complementary DNA (cDNA) copies (approximately 150 to 200 nucleotides in length) of RD-114 RNA were prepared by an endogenous synthesis; labels of polydeoxythymidylic acid [poly(dT)] were attached to the 3' ends of the cDNA molecules by a reaction catalyzed by deoxynucleotidyl terminal transferase. The cDNA-poly(dT) was hybridized to RD-114 RNA and to baboon viral RNA dimer (50 to 70S) units, and the position- of the poly(dT) labels were observed by electron microscopy. With RD-114, labels were distributed uniformly along the genome. With baboon virus RNA (monomer length, 9.5 kilobases [kb]), the regions of high homology with RD-114 cDNA were observed to lie in the intervals from 1.5 to 2.5 kb and from 3.7 to 5.5 kb from the 5' end. The relations of these heteroduplex maps to the known antigenic similarities and differences among the several viral proteins and to the genetic maps of the viruses are discussed.

A heteroduplex study of the sequence relationships between the RNAs of M-MSV and M-MLV

The regions of sequence homology between the RNA genomes of a murine sarcoma virus (clone 124 Moloney-MSV) and its parental helper virus (clone 3 Moloney-murine leukemia virus (M-MLV)) have been mapped. Long complementary DNA transcripts of the M-MLV RNA were hybridized to M-MSV RNA, and the structures of the hybrids were observed in the electron microscope. Beginning at the 5' end, the two RNAs are homologous for a region of length 2.25 kb (kilobases). In the next region, of length approximately 4.2 kb on the MLV genome, there are several homology segments between MLV and MSV, but there are also several short sequences present on MLV and deleted in MSV. There is then a major substitution loop; with a sequence (beta L) of length 2.9 kb present on MLV and missing on MSV, and a sequence (beta S) of length 1.5 kb present on MSV and missing on MLV. At the 3' end, there is a homology sequence of length 0.8 kb. On the basis of these results, other data on genes expressed in M-MSV-transformed cells, and by analogy with the avian gene map, we suggest that the gag genes (internal structural proteins) lie in the 2.25 kb region of homology near the 5' ends of M-MSV and M-MLV RNAs, and that the beta S segment contains a sarcoma (src) gene. Some of the heteroduplexes and some of the MLV cDNA/MLV RNA homoduplexes are circular, thus showing that cDNA transcription is initiated at an internal position in the RNA, proceeds to the 5' end, and them "jumps" to the 3' end.

Heteroduplex analysis of avian RNA tumor viruses

Electron microscopic heteroduplex analysis of avian RNA tumor viruses has been undertaken by using 35S viral RNA and long, complementary DNA synthesized in vitro. In this initial study, heteroduplex molecules were formed between complementary DNA from Rous sarcoma virus [Prague B strain (Pr-B)] and RNAs from Pr-B and Rous sarcoma virus [Prague C strain (Pr-C)] and from their transformation defective (td) derivatives, td-Pr-B and td-Pr-C. In the case of heteroduplexes with the td viruses, a deletion loop was observed of the order of two kilobases in size and less than one kilobase from the 3' terminus of the RNA. This deletion probably spans part or all of the sequences of one or more genes in the nondefective sarcoma virus which are essential for cell transformation. The sizes and the positions of the deletions in the td-Pr-B and td-Pr-C viruses were slightly, but significantly, different. No nonhomology features were observed in the Pr-B-Pr-C hybrids, thus confirming the close genetic relatedness of the two viruses. All heteroduplexes contained a proportion of circular and dimer molecules. This observation is a direct demonstration that (-) strand DNA transcription begins at an internal position of the RNA genome, proceeds to the 5' end, reinitiates at the 3' end of the RNA, and copies the remainder of the viral genome. Other implications for models of RNA tumor virus replication are also developed from these data.

RD-114, baboon, and woolly monkey viral RNA's compared in size and structure

The molecular weights, subunit compositions, and secondary structure patterns of the RNAs from an endogenous baboon virus and from a woolly monkey sarcoma virus were examined and compared to the properties of the RNA of RD-114, an endogenous feline virus. The high molecular weight RNA extracted from each of these three viruses has a sedimentation coefficient of 52S, and a molecular length, measured by electron microscopy, of 16-20 kb (kb=kilobase, 1000 nucleotides). Each such RNA is a dimer, containing two monomer subunits of 8-10 kb in length (molecular weight 3 X 10(6) daltons). The two monomer subunits are joined at their non-poly(A) ends in a structure called the dimer linkage structure. The appearance of this structure is somewhat different for the different viruses. The dimer linkage dissociates at temperature estimated to be 87 degrees C in aqueous 0.1M Na+ for RD-114 and baboon viral RNAs, but at the lower temperature of 66 degrees C for woolly monkey RNA. All three viral RNAs have two large loops of similar size and position symmetrically placed on either side of the dimer linkage structure. Since the baboon virus is partially related to RD-114, and the woolly monkey virus is unrelated to either of the other two, the dimer linkage and symmetrical loops are surprisingly similar and may well be common features of type C virus RNAs.