A copper-thiolate polynuclear cluster in the ACE1 transcription factor

ACE1 is the transcriptional activator of the metallothionein (CUP1 locus) gene in Saccharomyces cerevisiae. Previous data had implicated the N-terminal domain of ACE1 as responsible for the Cu-dependent specific DNA binding. An expression system in Escherichia coli was constructed to enable the isolation of an ACE1 domain containing the DNA and Cu-binding regions. Here we report the purification and characterization of the Cu-ACE1 truncated molecule. Spectroscopic techniques showed that ACE1 contains an unusual type of DNA binding structure that is based on a polynuclear Cu(I)-cysteinyl thiolate cluster. The cluster consists of six or seven Cu(I) ions coordinated to cysteinyl thiolates in a trigonal geometry distorted from planarity. The Cu(I)-cysteine cluster of Cu-ACE1 exhibits structural properties analogous to the Cu(I)-thiolate polynuclear cluster in yeast Cu-metallothionein itself, suggesting an unusual mechanism for the evolution of this regulatory factor. The Cu cluster organizes and stabilizes the conformation of the N-terminal domain of ACE1 for specific DNA binding.

[Analysis of Trace elements in processed products of Pinellia ternata (Thunb.) Breit]

This article reports the detecting result of trace elements in processed products of Pinellia ternata and of the contents of As, Hg, Pb in the products processed with sulfur. The result shows that all the processing procedures are necessary and safe.

Spectroscopic characterization of the copper(I)-thiolate cluster in the DNA-binding domain of yeast ACE1 transcription factor

A polypeptide containing the amino-terminal region of ACE1 (residues 1-122; 122*), the activator of yeast Cu-metallothionein gene transcription, shows charge-transfer and metal-centered UV absorption bands, and orange luminescence which are characteristic of Cu-cysteinyl thiolate cluster structures. These spectral features are abolished by the Cu(I) complexing agents CN- and diethyldithiocarbamate or exposure to acid, but not by the Cu(II) chelator, EDTA. Binding of the polypeptide to its specific DNA recognition site, but not to calf-thymus double-stranded DNA, induces quenching of its Tyr and Cu-S cluster luminescence emission. The CD spectrum is characteristic of a tightly folded structure that may be organized around the Cu cluster.

Motion sickness severity and physiological correlates during repeated exposures to a rotating optokinetic drum

Fifty-two subjects were exposed to a rotating optokinetic drum. Ten of these subjects who became motion sick during the first session completed two additional sessions. Subjects' symptoms of motion sickness, perception of self-motion, electrogastrograms (EGGs), heart rate, mean successive differences of R-R intervals (RRI), and skin conductance were recorded for each session. The results from the first session indicated that the development of motion sickness was accompanied by increased EGG 4-9 cpm activity (gastric tachyarrhythmia), decreased mean successive differences of RRI, increased skin conductance levels, and increased self-motion perception. The results from the subjects who had three repeated sessions showed that 4-9 cpm EGG activity, skin conductance levels, perception of self-motion, and symptoms of motion sickness all increased significantly during the drum rotation period of the first session, but increased significantly less during the following sessions. Mean successive differences of RRI decreased significantly during the drum rotation period for the first session, but decreased significantly less during the following sessions. In conclusion, we have demonstrated that the development of motion sickness is accompanied by an increase in gastric tachyarrhythmia, and an increase in sympathetic activity and a decrease in parasympathetic activity, and that adaptation to motion sickness is accompanied by the recovery of autonomic nervous system balance.

GABA accumulating neurons are relatively resistant to chronic hypoxia in vitro: an autoradiographic study

Whether there is preferential loss of certain types of nerve cells or specific cellular functions after hypoxic or ischemic insults remains unclear. To evaluate this phenomenon in vitro, the vulnerability of GABAergic neurons to hypoxia was investigated both quantitatively and with autoradiography. Immature neuronal cortical cultures obtained from fetal mice were subjected to chronic hypoxia (5% O2) for 24 h or 48 h and then returned to the normoxic condition for 48 h. The shorter hypoxic exposure resulted in significantly reduced numbers of neurons in comparison to the longer exposure and also to controls (29% and 26%, respectively; p less than 0.001). LDH efflux, a reliable indicator of cell damage, also was higher after the shorter exposure insult. Nevertheless, in these same 24 h hypoxic cultures there was prominent sparing of those neurons which accumulate GABA: by 48 h of recovery GABAergic neurons constituted 29.3 +/- 2.0% of the remaining neuronal population in comparison to 11.6 +/- 0.6 and 14.4 +/- 0.8% for controls and 48 h hypoxia, respectively; (p less than 0.001). Although total GABA uptake per neuron was significantly decreased after both types of insult, there was a concomitant increase in glial GABA uptake (i.e., that which could be displaced by beta-alanine). These observations suggest that certain GABAergic cortical neurons are relatively more resistant to chronic hypoxia than the general neuronal population and that depression of overall neuronal GABA uptake may be associated with enhanced glial GABA uptake.

The single-minded gene of Drosophila is required for the expression of genes important for the development of CNS midline cells

The single-minded (sim) gene of Drosophila encodes a nuclear protein that plays a critical role in the development of the neurons, glia, and other nonneuronal cells that lie along the midline of the embryonic CNS. Using distinct cell fate markers, we observe that in sim mutant embryos the midline cells fail to differentiate properly into their mature CNS cell types and do not take their appropriate positions within the developing CNS. We further present evidence that sim is required for midline expression of a group of genes including slit, Toll, rhomboid, engrailed, and a gene at 91F; that the sim mutant CNS defect may be largely due to loss of midline slit expression; and that the snail gene is required to repress sim and other midline genes in the presumptive mesoderm.

The effects of fixation and restricted visual field on vection-induced motion sickness

Approximately 60% of healthy human subjects experience motion sickness when exposed to a rotating optokinetic drum. The purpose of the present study was to determine the effects of certain visual factors on susceptibility to motion sickness. Vection data (illusory self-motion), horizontal eye movement recordings, subjective motion sickness report, and a measure of gastric myoelectric activity (electrogastrogram, EGG) were obtained from 45 subjects, who were randomly divided into the following three groups: a control group that observed the entire visual field with no fixation, a group that fixated on a central target, and a third group that had a visual field restricted to 15 degrees. The experimental session was divided into the following three 12-min periods: baseline, drum rotation, and recovery. The results showed that fixation greatly reduced nystagmus and slightly reduced vection. The restricted visual field slightly reduced nystagmus and greatly reduced vection. Both of these manipulations significantly reduced symptoms of motion sickness and tachyarrhythmia, the abnormal gastric myoelectric activity that usually accompanies nausea.

The DNA and Cu binding functions of ACE1 are interdigitated within a single domain

We present genetic and biochemical evidence that the amino-terminal region of ACE1, the activator of yeast Cu-metallothionein gene transcription, is composed of a single domain in which the DNA- and Cu-binding residues are interdigitated. Analysis of truncation mutants showed that both the DNA and Cu interactions functions of ACE1 are contained within an amino-terminal 101 amino acid peptide that can fold into a protease-resistant domain structure. Studies of point mutants revealed that two basic residues within this domain are required for efficient DNA binding although not for productive interaction with Cu. Mutations at these sites alter the specificity of ACE1 for two binding sites in the upstream activation region, both of which are shown to be necessary for efficient transcription in vivo. Systematic mutagenesis of the 12 cysteine residues in ACE1 showed that all 11 cysteines within the minimal DNA-binding domain are required for ACE1 to undergo a Cu-induced conformational switch into an active DNA-binding protein. A twelfth cysteine, located outside the DNA-binding domain, is not required for proper folding. The critical basic and cysteine residues of ACE1 are interdigitated, thereby providing an unusual example of overlapping small molecule and DNA binding functions within a directly regulated transcription factor. In contrast, the carboxyl-terminal region of ACE1 is shown to contain a constitutive trans-activation domain that is spatially distinct and functionally dissociable from the DNA- and Cu-binding domain.

[The X-ray characteristic feature of the multiple primary malignant tumor of digestive tract]

A study on the multiple primary malignant tumor of digestive tract (MPMTDT) was made in the period of 1984-1988 in our hospital. Twenty five cases are reported in this paper. All of them were examined by X-ray, endoscopy, and proved to be MPMTDT by surgery and pathological examination. Twenty three cases were double primary tumors and 2 cases triple primary malignant tumors. The characteristic X-ray feature of the site of predilection and manifestation in primordial period of MPMTDT are described in this paper. These criteria are important for the early detection and selection of treatment of the tumors.

[Thromboxane and prostacyclin in endotoxin-induced lung injury]

Hypotension, respiratory failure and ARDS-like pulmonary morphological changes were induced by given continuous intravenous infusion of E. coli endotoxin (1-1.5 micrograms.kg/h) in goats. During endotoxin infusion, plasma TXB2 level rose markedly with peak at 0.5 h and then lowered, while 6-keto-PGF1 alpha elevated progressively with its highest level before death, and correlated with blood pressure and survival times negatively. So we suggested that prostacyclin may be one of the factors responsible for hypotension and death in late period of endotoxin induced shock and lung injury.

The effect of worry on cardiovascular response to phobic imagery

Cardiovascular response to phobic exposures has been shown to reflect the degree of emotional processing of phobic material and relates in important ways to outcome in exposure therapy. The present study investigated the effect of worry on such processing. Speech anxious subjects visualized a phobic scene for 10 trials. Three groups differed according to whether they engaged in relaxed, neutral, or worrisome thinking just prior to each scene presentation. Although the three types of thinking had no effect on cardiovascular activity during the thinking periods, subjects in the worry group displayed significantly less heart rate response to the phobic image than those in the neutral condition who had significantly less response than the relaxed condition. However, the worry group showed significantly greater subjective fear to the images than the neutral condition, with the relaxed group near to the level of the worry group and not significantly different from either of the other two conditions. The results suggest that worry may inhibit emotional processing and thus preserve cognitive/affective fear structure, and are discussed in terms of Gray's (Behavioral and Brain Sciences, 5, 469-534, 1982) theory of the behavioral inhibition system and semantic satiation effects in cognitive psychology.

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.

A contribution to our knowledge of Leonurus L., i-mu-ts'ao, the Chinese motherwort

This article deals with the ethnobotanical aspects of the Chinese motherwort. Since time immemorial the Chinese people have used various parts of motherwort to meet different physical needs. By the time a written language was developed and the medical uses were recorded. , motherwort was treated as an article of superior quality. At present, under the name of i-mu-ts'ao, the plant is used for improving bloodflow both by official physicians and herbal practitioners throughout the country as well as by villagers in isolated areas. According to Chinese classical literature on materia medica, the early uses were limited to the parts of the plant which met the most obvious needs of the prehistorical people in their struggle for existence-food and pain reliever. Evidently, in their search for food, the ancient people found that the four nutlets contained in the dry and spinose calyx of the Chinese motherwort resemble the seasame seed in size and oil content. They gathered them and used them for food in similar manner as with the sesame. Consequently, they discovered the good effects to the eyesight, the improvement of strength, and the uplift of spirit. These discoveries led to the use of the seed of the species as an eye medicine for improving the eyesight, and as a tonic for the increase of strength and the elevation of spirit. Contagious skin diseases caused serious problems for the ancient people. The use of the leafy shoot for a bath to release the discomfort of itches and shingles was also recorded in the 42-word first medicinal record of the species in the earliest known Chinese materia medica-the Shen-nung pen-ts'ao-ching. Translators of the Chinese classics have included the records of i-mu-ts'ao. According to my knowledge, these works are all partial translations with the selections of the medicinal properties and the omissions on the methods of preparation. They have the outline and abandon the details. Consequently most of them are not clear. In order to provide complete information on the discoveries of the ancient Chinese people on the uses of i-mu-ts'ao, all the records up to the end of the sixteenth century are organized and translated under the following headings: (1) ecological and morphological observations; (2) preparations; (3) physical and therapeutical properties; (4) special prescriptions for internal and external uses-including pills for pregnant women, for mothers post partum, as an emmenagogue, and as a corrective agent, condensed liquid, powder, fresh juice, baby bath and washes, poultices, charred shoots, gargles, drops and cakes; (5) other economic uses-including cosmetics and food; and (6) etymology. The distribution of i-mu-ts'ao is significant in photogeography and in the nomenclature of the species. I-mu-ts'ao was purposely introduced from South China to Linnaeus in Sweden before the publication of the Species Plantarum in 1753. Linnaeus planted the seed in the botanical garden of the University of Uppsala...

alphabeta sequence of F is IS31

Previous studies have shown that there is a deoxyribonucleic acid (DNA) segment, of length 1.3 kb and denoted as the alphabeta sequence, which occurs twice on the F plasmid at corrdinates 93.2 to 94.5/OF kb and 13.7 to 15.0F kb. In the present investigation, heteroduplexes were prepared between a phage DNA carrying the insertion sequence IS3 and suitable F-prime DNAs. The hybrids formed show that IS3 is the same as alphabeta. This result plus previous studies support the view that: (i) the insertion sequence IS2 and IS3 occur on F and, in multiple copies, on the main bacterial chromosome of Escherichia coli K-12; and (ii)these IS sequences on the main bacterial chromosomes are hot spots for Hfr formation by reciprocal recombination with the corresponding sequences of F.

Electron microscopic heteroduplex studies of sequence relations among plasmids of Escherichia coli: structure of F13 and related F-primes

The structure of F13, a plasmid containing lac, purE, and proC, has been determined by heteroduplex analysis. As expected for an F-prime formed by a type II excision event, it contains all the sequences of F plus a large segment of Escherichia coli chromosomal deoxyribonucleic acid. There is a sequence of F with coordinates 16.3-17.6F which has been shown in other studies to be the insertion sequence IS2. This IS2 occurs twice on F13, once at each of the two junctions of F deoxyribonucleic acid with chromosomal deoxyribonucleic acid. The sequence alpha beta which occurs twice on F with coordinates 93.2-94.5/OF and 13.7-15.0F occurs an additional three times, twice in an inverted order relative to the alpha beta sequences of F, on the chromosomal sequences of F13. The structures of the plasmids F13-4 and F210 have been determined. The common sequences of F13 with F152-1 (a derivative of F152, the classical F2gal) and with F13-4 and F210 have been mapped. These results partially map lac, proC, tsx, and purE on F13. On the basis of all of these results, it is proposed that Hfr 13 (the parent of F13) was formed by recirpocal recombination between IS2 on F and an IS2 resident at a point between lac and proC on the chromosome of the F+ parent of Hfr 13. It is proposed that this IS2 and the several alpha beta sequences on the chromosomal part of F13 are hot spots for recombination with F, i.e., for Hfr formation. The point of origin and direction of transfer of many Hfr's can be explained by this hypothesis. In particular, the sequence relations of F42-1 (Flac) and of F152-1 (F 2gal) with F13 are completely consistent with this model.

Electron microscope heteroduplex studies of sequence relations among bacterial plasmids: identification and mapping of the insertion sequences IS1 and IS2 in F and R plasmids

Heteroduplex experiments between the plasmid R6 and one strand of the deoxyribonucleic acid (DNA) of a lambda phage carrying the insertion sequence IS1 show that IS1 occurs on R6 at the two previously mapped junctions of resistance transfer factor (RTF) DNA with R-determinant DNA. From previous heteroduplex experiments, it then follows that IS1 occurs at the same junctions in R6-5, R100-1, and R1 plasmids. Heteroduplex experiments with the DNA from a lambda phage carrying the insertion sequence IS2 show that one copy of IS2 occurs in R6, R6-5, and R100-1 (but not R1) at a point within the RTF with coordinates 67.5 TO 68.9 kilobase units (kb). In an accompanying paper, Ptashne and Cohen (1975) show that the insertion sequence IS3 occurs on R6 and R6-5. R100-25, a traC mutant, differs from its parent R100-1 only in that it contains an additional copy of IS1 inserted within the tra gene region of 82.1 kb. R100-31, atraX, TC-s mutant of R100-1, is deleted in R100-1 sequences starting at one of the IS3 termini (46.9 kb) and extending with RTF to 61.0 kb. Heteroduplex studies of F plasmids with the DNA of a lambda phage bearing insertion sequence IS2 show that the sequence of F with coordinates 16.3-17.6F is IS2. The occurrence of IS1 at the two junctions of R-determinant DNA and RTF DNA in R plasmids provides a structural basis to explain the mechanism of the previously observed formation of molecules containing one RTF unit and several tandem copies of the R-determinant unit, when R plasmids in Proteus mirabilis are grown in the presence of antibiotics, and the segregation of an R plasmid into an RTF unit and an R-determinant unit. In general, correlation of our results with previous studies shows that insertion sequences play a role in a variety of F- and R-related intra- and intermolecular recombination phenomena.