Parity-Protected Superconductor-Semiconductor Qubit.

Coherence of superconducting qubits can be improved by implementing designs that protect the parity of Cooper pairs on superconducting islands. Here, we introduce a parity-protected qubit based on voltage-controlled semiconductor nanowire Josephson junctions, taking advantage of the higher harmonic content in the energy-phase relation of few-channel junctions. A symmetric interferometer formed by two such junctions, gate-tuned into balance and frustrated by a half-quantum of applied flux, yields a cos(2φ) Josephson element, reflecting coherent transport of pairs of Cooper pairs. We demonstrate that relaxation of the qubit can be suppressed tenfold by tuning into the protected regime.

Transcriptional regulation of ribosomal proteins during a nutritional upshift in Saccharomyces cerevisiae.

The relative rates of synthesis of Saccharomyces cerevisiae ribosomal proteins increase coordinately during a nutritional upshift. We constructed a gene fusion which contained 528 base pairs of sequence upstream from and including the TATA box of ribosomal protein gene rp55-1 (S16A-1) fused to a CYC1-lacZ fusion. This fusion was integrated in single copy at the rp55-1 locus in the yeast genome. During a nutritional upshift, in which glucose was added to cells growing in an ethanol-based medium, we found that the increase in the relative rate of synthesis of the beta-galactosidase protein product followed the same kinetics as the change in relative rates of synthesis of several ribosomal proteins measured in the same experiment. This demonstrates that the nontranscribed sequences upstream from the rp55-1 gene, which are present in the fusion, are sufficient to mediate the change in rates of synthesis characteristic of ribosomal proteins under these conditions. The results also suggest that a change in transcription rates is mainly responsible for the increase in relative rates of synthesis of ribosomal proteins during a nutritional upshift in S. cerevisiae.

A suppressor of temperature-sensitive rna mutations that affect mRNA metabolism in Saccharomyces cerevisiae.

We have isolated a dominant suppressor of rna mutation (SRN1) that relieves the temperature-sensitive inhibition of mRNA synthesis of ribosomal protein genes in the yeast Saccharomyces cerevisiae. The suppressor was selected for its ability to alleviate simultaneously the temperature-sensitive growth phenotypes of rna2 and rna6. Several independently isolated suppressors appeared to be recessive lethal mutations. One suppressor, SRN1, was recovered as viable in haploid strains. SRN1 can suppress rna2, rna3, rna4, rna5, rna6, and rna8 singly or in pairs, although some combinations of rna mutations are less well suppressed than others. The suppressor allows strains with rna mutations to grow at 34 degrees C but is unable to suppress at 37 degrees C; however, SRN1 does not, by itself, prevent growth at 37 degrees C. In addition, SRN1 suppresses the rna1 mutation which affects general mRNA levels and also leads to the accumulation of precursor tRNA for those tRNAs that have intervening sequences. SRN1 can suppress the rna1 mutation as well as the rna1 rna2 double mutation at 34 degrees C. The suppressor does not affect the temperature-sensitive growth of two unrelated temperature-sensitive mutations, cdc4 and cdc7.

Functional analysis of a duplicated linked pair of ribosomal protein genes in Saccharomyces cerevisiae.

Ribosomal protein genes RP28 and S16A (RP55) are closely linked. Another set of this pair of genes exists in the genome (copy 2), genetically unlinked to copy 1. By using gene replacement techniques, we have shown that RP28 from copy 1 is required for vegetative growth and that the cells need S16A from copy 2 to achieve maximum growth rate.

Semiautomated determination of minimum bactericidal concentrations of antibiotics.

Using a newly devised 50-channel photometer which records the opacity of growing bacterial cultures, it was shown that the time taken by cultures diluted 1/1000 in fresh broth to reach 50% of the opacity of a fully grown culture was inversely related to the concentration of organisms in the original culture. This relation was used to determine the numbers of survivors after exposure to benzylpenicillin and gentamicin alone and in combination. The procedure is commended as a labour-saving and potentially rapid method of obtaining comprehensive information on the bactericidal action and interaction of antibiotics.

Use of a non-radioactive hybridisation assay for direct detection of gram-negative bacteria carrying TEM beta-lactamase genes in infected urine.

DNA in infected urines from 81 patients with urinary tract infection was hybridised directly with a non-radioactive DNA probe specific for bacterial genes coding for TEM-type beta-lactamase. The results were assessed by means of a computerised image analysis system and compared with those obtained following isolation of the infecting organism, conventional sensitivity testing and isoelectric focusing (IEF) procedures for the detection of TEM-type beta-lactamase. Of the 27 ampicillin-resistant gram-negative organisms isolated in pure culture from the urines, 14 were shown by both hybridisation and IEF to carry a gene for TEM beta-lactamase production. Only four discordant results were obtained: three "false positive" direct hybridisation results, one due to urine pigmentation, and one, possibly, to a TEM beta-lactamase gene which was not being expressed, and one "false negative" result due to insufficient cell numbers in the urine. The system is capable of screening large numbers of samples and is applicable to any gene for which a suitable DNA probe is available.

Isolation of a rotavirus from a newborn dog with diarrhea.

A rotavirus was isolated from a newborn dog that died after having clinical signs of diarrhea. Virus particles with rotaviral morphologic features were observed by transmission electron microscopy in the intestinal homogenate collected at necropsy. Cytopathic effects were observed, and rotaviral antigens were detected by indirect immunofluorescence in MA-104 monolayer cultures (a fetal rhesus macaque kidney cell) inoculated with intestinal homogenate. This rotavirus isolate, designated LSU 79C-36, may be a specific canine rotavirus or a rotavirus from another species.

Bluetongue infections in Louisiana cattle.

Bluetongue virus (BTV) serotype 17 was isolated from cattle with clinical signs of bluetongue disease during 1978 and 1979 epizootics. Bovine sera from 6 herds located in an epizootic region were examined in 1979 for antibodies, using an immunodiffusion (ID) test. Of 300 sera, 164 (54.7%) were seropositive. Sera from statewide surveys of Louisiana cattle in July to August 1980 and December 1980 to January 1981 were tested for BTV antibodies, using the ID test. Fifty-eight of 70 herds (82.9%) and 164 of 597 (27.5%) individual cattle tested in July to August 1980 were seropositive. Fifty-four of 63 (85.7%) herds and 170 of 600 (28.3%) individual cattle tested in December 1980 to January 1981 were seropositive. Significant differences (P less than 0.01) were found in the seropositive rates between the various geographic regions of the state during each survey. Adult breeding-age cattle in 3 sentinel herds were tested for BTV antibodies beginning in 1976 and continuing through January 1981. During this interval, the seropositive rate in 2 of 3 herds was increased. Also, individual cattle in all 3 of these herds converted from seronegative to seropositive, indicating exposure during a particular interval for each herd. The age distribution of seropositive cattle in a dairy indicated that 2-year-old cattle had a seropositive rate comparable with that of older animals in the herd, suggesting that the 2-year-old animals had been exposed to a BTV before they entered the breeding herd.

Isolation of a chlamydial agent from Rocky Mountain bighorn sheep.

A total of 53 clinical specimens from both healthy and diseased Rocky Mountain bighorn sheep (Ovis canadensis) were examined for Chlamydia. An agent consistently lethal for chicken embryos was recovered from a nasal swab taken from a normal ewe. This agent, designated BHS-15, possesses antigens which fix complement in the presence of anti-chlamydial serum, is susceptible to chlortetracycline, and is resistant to sodium sulfadiazine and streptomycin. Attempts to culture the isolate in quality control media, including blood agar, thioglycolate broth, and PPLO broth and agar were unsuccessful. A recommendation is made for classification of agent BHS-15 as a member of the species Chlamydia psittaci. The possible relationship of the isolate to the pneumonia complex in bighorn sheep is discussed.

Isolation of feline herpesvirus 1 from a young kitten.

Five kittens exposed neonatally to older cats exhibiting fever with nasal and ocular discharge became ill and died within 10 days of the onset of illness. One kitten which died at 16 days old was examined post mortem and feline herpesvirus 1 was isolated from the brain, liver, lung and spleen.

The role of promoter elements of a ribosomal protein gene in Saccharomyces cerevisiae under various physiological conditions.

Previous work in our laboratory has shown that the 5' nontranscribed promoter region of the gene for ribosomal protein (rp) S16A-1 of Saccharomyces cerevisiae, when fused to a lacZ gene, is necessary and sufficient to cause an increase in expression of the heterologous lacZ gene fusion product after cells have been shifted from a glycerol to glucose carbon source. This increase in expression is characteristic of that observed with the native rp gene. We have sought to define more precisely those areas of the promoter that may be involved in the differential expression/regulation of RPS16A-1 when host cells are subjected to a variety of nutritional environments. It has already been demonstrated by others that the promoter regions of most rp genes contain at least one consensus element, designated UASrpg, which is necessary for the transcriptional activation and maintenance of expression of the gene during steady-state growth in rich media. Our main experimental approach has been to create a series of 5' end deletions in the promoter region of RPS16A-1. The individual truncated promoter fragments were then ligated to a lacZ fusion reporter construct. By assaying the cells for production of beta-galactosidase and determining the abundance of lacZ mRNA, we have been able to determined the extent of fusion product expression. We assayed cells under three physiological conditions: steady-state growth in glucose, steady-state growth in glycerol and during sporulation. We report four main findings of our work.

Genetic mapping of two pairs of linked ribosomal protein genes in Saccharomyces cerevisiae.

We have used the 2 mu mapping method described by Falco and Botstein (1983) and tetrad analysis to map four ribosomal protein genes (two linked pairs) in S. cerevisiae. One pair (rp28-rp55 copy 1) is on chromosome XV, 14 cM proximal to ARG8. The other pair (rp55-rp28 copy 2) is 19 cM from the centromere on the left arm of chromosome XIV. To map copy 1 we used the E. coli beta-galactosidase gene rather than a yeast gene to mark the ribosomal protein chromosomal locus. This provided a more sensitive color screening assay for chromosome loss in the 2 mu method. It also removed the restriction that the mapping tester strains must be mutant for the plasmid marker.

Interferon production by bovine tracheal organ cultures infected with bovid herpesvirus 1 strains.

Studies have been made of antiviral inhibitors produced by bovine tracheal organ cultures inoculated with strains of bovid herpesvirus 1. The inhibitors, which had properties of interferon, were assayed by a plaque-reduction method in bovine turbinate cell cultures with vesicular stomatitis virus as challenge virus. Each of the four strains of bovid herpesvirus 1 studied induced interferon in bovine tracheal organ cultures.

Changes in regulation of ribosomal protein synthesis during vegetative growth and sporulation of Saccharomyces cerevisiae.

When diploid Saccharomyces cerevisiae cells logarithmically growing in acetate medium were placed in sporulation medium, the relative rates of synthesis of 40 or more individual ribosomal proteins (r-proteins) were coordinately depressed to approximately 20% of those of growing cells. These new depressed rates remained constant for at least 10 h into sporulation. If yeast nitrogen base was added 4 yh after the beginning of sporulation to shift the cells back to vegetative growth, the original relative rates of r-protein synthesis were rapidly reestablished. this upshift in the rates occurred even in diploids homozygous for the regulatory mutation rna2 at the restrictive temperature for this mutation (34 degrees C). However, once these mutant cells began to bud and grow at 34 degrees C, the phenotype of rna2 was expressed and the syntheses of r-proteins were again coordinately depressed. At least one protein whose rate of synthesis was not depressed by rna2 in vegetative cells did have a decreased rate of synthesis during sporulation. Another r-protein whose synthesis was depressed by rna2 maintained a high rate of synthesis at the beginning of sporulation. These data suggest that the mechanism responsible for coordinate control of r-protein synthesis during sporulation does not require the gene product of RNA2 and thus defines a separate mechanism by which r-proteins are coordinately controlled in S. cerevisiae.

Interferon induction in bovine and feline monolayer cultures by four bluetongue virus serotypes.

The interferon inducing ability of bluetongue viruses was studied in bovine and feline monolayer cultures inoculated with each of four bluetongue virus serotypes. Interferon was assayed by a plaque reduction method in monolayer cultures with vesicular stomatitis virus as challenge virus. Interferon was produced by bovine turbinate, Georgia bovine kidney, and Crandell feline kidney monolayer cultures in response to bluetongue virus serotypes 10, 11, 13 and 17. The antiviral substances produced by the bluetongue virus infected cultures had properties of interferon.

Changes in regulation of ribosome synthesis during different stages of the life cycle of Saccharomyces cerevisiae.

Diploid strains of Saccharomyces cerevisiae, each homozygous for one of the temperature sensitive mutations rna2, rna3, rna4, rna6 or rna8, are temperature sensitive for ribosome synthesis during vegetative growth, but are not inhibited for ribosomal synthesis at the restrictive temperature under sporulation conditions. The continued ribosome biosynthesis at the restrictive temperature (34 degrees C) during sporulation includes de novo synthesis of both ribosomal RNA and ribosomal proteins. This lack of inhibition of ribosome biosynthesis is found even when cells committed to complete sporulation are returned to vegetative growth medium. The ribosomes synthesized at 34 degrees C are apparently functional, as they are found in polyribosomes. Although the rna mutants do not regulate ribosome synthesis during sporulation, all of these diploid strains fail to complete sporulation at 34 degrees C. The cells are arrested after the second meiotic nuclear division but before ascus formation. The failure to complete sporulation at the restrictive temperature and the inhibition of ribosome biosynthesis during growth are caused by the same mutation, because revertants selected for temperature independent growth were also able to sporulate at 34 degrees C.

Construction and characterization of a haploid strain of Saccharomyces cerevisiae that completely lacks all genomic CYH2 sequences.

A diploid strain of the yeast Saccharomyces cerevisiae has been constructed that has one copy of the ribosomal protein gene CYH2 completely deleted and replaced with the TRP1 gene using the method of Rothstein (1983). There are only small differences in growth rate and no detectable difference in steady state level of CYH2 mRNA between the diploid that is heterozygous for the CYH2 deletion and the parent diploid with two normal copies of this gene. This suggests that the diploid must partially compensate for the loss of one CYH2 gene. Tetrad dissection shows that haploid spores lacking the CYH2 gene cannot germinate. The lethality of this deletion can be rescued by a CYH2 cDNA on a low copy vector. Haploids which lack the genomic copy of the CYH2 gene, but contain a plasmid copy of the CYH2 cDNA are able to grow normally. These CYH2 deleted yeast haploids should be useful to analyze mutationally altered CYH2 genes and genes homologous to CYH2 from other organisms without interference from a genomic copy.