| 1. |
- Thomas, C M, et al.
(författare)
-
Regulation of replication and maintenance functions of broad host-range plasmid RK2.
- 1985
-
Ingår i: Basic life sciences. - 0090-5542. ; 30
-
Tidskriftsartikel (refereegranskat)abstract
- Replication of broad host-range plasmid RK2 depends on a cisacting vegatative replication origin oriVRK2 and the polypeptide product(s) of the trans-acting gene trfA as well as on host-specified products. The trfA gene is the second cistron in a polycistronic unit whose first cistron may be kilD, one of 4 known RK2-specified kil loci (kilA, B, C, and D) which are inhibitory for bacterial host or plasmid vector in the absence of kor functions which suppress in trans the effect of their respective kil genes. Transcription of the operon containing trfA is negatively regulated by the products of both the trfB locus (alias korD and korA) and korB. The loci, trfB and korB, are expressed from a single transcriptional unit which we propose to be negatively autoregulated by the products of both loci, although an additional, weaker and unregulated transcript may also express korB. While deletions in the oriVRK2 region have indicated the presence of copy number control elements adjacent to and possibly overlapping with the minimal oriVRK2 segment, the overriding control of copy number seems to reside in the trfB and korB loci which in conjunction appear to reduce expression of the trfA gene to levels limiting for replication. Coregulation of trfA with kil genes may indicate that kil genes play a role in plasmid maintenance other than replication.
|
|
| 2. |
- Abrahamsson, Per-Anders, et al.
(författare)
-
Radioimmunoassay of beta-microseminoprotein, a prostatic-secreted protein present in sera of both men and women
- 1989
-
Ingår i: Clinical Chemistry. - 0009-9147. ; 35:7, s. 1497-1503
-
Tidskriftsartikel (refereegranskat)abstract
- We describe a simple radioimmunoassay of beta-microseminoprotein, one of the three most abundant secretory proteins of the prostate gland. The detection limit of the assay is 1 microgram/L, and its precision, expressed as the total coefficient of variation, is less than 10% for values between 10 and 150 micrograms/L. Using this assay, we found that beta-microseminoprotein immunoreactivity was present in sera from both sexes at about the same concentration. The protein detected had the same molecular size on gel chromatography as the protein isolated from seminal plasma, and dilution curves for the sera paralleled that for the pure protein. The findings suggest that beta-microseminoprotein is present in serum of healthy subjects of both sexes and that it originates in tissue other than the prostate gland. The range of the serum concentration was 0-10.6 micrograms/L (median 4.1) for 51 healthy adult women and 1.1-14.7 micrograms/L (median 6.2) for 35 healthy adult men not older than 40 years. In males with prostatic cancer the concentration in serum was highly variable and often greatly increased. The concentration of beta-microseminoprotein was correlated with that of creatinine in serum, suggesting that the protein is eliminated--at least partly--from the circulation by glomerular filtration. Little of the protein was present in the urine of women. In urine from men the concentration was high and variable, probably because of local contribution from the prostate gland to the urethral urine.
|
|
| 3. |
- Baker, Thomas C., et al.
(författare)
-
Adaptation of antennal neurons in moths is associated with cessation of pheromone-mediated upwind flight
- 1988
-
Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424. ; 85:24, s. 9826-9830
-
Tidskriftsartikel (refereegranskat)abstract
- A wind-borne plume of sex pheromone from a female moth or a synthetic source has a fine, filamentous structure that creates steep and rapid fluctuations in concentration from a male moth flying up the plume's axis. The firing rates from single antennal neurons on Agrotis segetum antennae decreased to nearly zero within seconds after the antennae were placed in a pheromone plume 70 cm downwind of a high-concentration source known from previous studies to cause in-flight arrestment of upwind progress. In a separate experiment, the fluctuating output from chilled neurons on Grapholita molesta antennae became attenuated in response to repetitive, experimentally delivered pheromone pulses. The attenuation was correlated with a previously reported higher percentage of in-flight arrestment exhibited by moths flying at cooler compared to warmer temperatures. These results indicate that two peripheral processes related to excessive concentration, complete adaptation of antennal neurons, or merely the attenuation of fluctuations in burst frequency, are important determinants of when upwind progress by a moth flying in a pheromone plume stops and changes to station keeping. Also, adaptation and attenuation may affect the sensation of blend quality by preferentially affecting cells sensitive to the most abundant components in airborne pheromone blends.
|
|
| 4. |
- Baker, Thomas C., et al.
(författare)
-
Adaptation of male moth antennal neurons in a pheromone plume is associated with cessation of pheromone-mediated flight
- 1989
-
Ingår i: Chemical Senses. - : Oxford University Press (OUP). - 0379-864X .- 1464-3553. ; 14:3, s. 439-448
-
Tidskriftsartikel (refereegranskat)abstract
- Recordings of the firing rates of single antennal neurons when Agrotis segetum antennac were placed 70 cm downwind of a pheromone source revealed that cells sensitive to the most volatile component adapted rapidly in a plume from a high-concentration source known from previous studies to cause in-flight arrestment of progress towards the source. No adaptation was found in response to lower-concentration plumes known to promote high levels of sustained flight to the source with little premature arrestment. Adaptation was not observed in antennal neurons of a second species, Heliothis virescens, when they were placed in plumes of this species' sex pheromone blend, regardless of the concentration. In flight-tunnel tests these same pheromone sources evoked high levels of source location with little arrestment. These results indicate that adaptation or attenuation of antennal neuronal burst frequencies in response to rapidly arriving pheromone filaments in a plume may be important peripheral determinants of whether or not prolonged upwind flight and successful pheromone source location occurs.
|
|
| 5. |
- Hammarström, Lennart, et al.
(författare)
-
Transfer of IgA deficiency to a bone-marrow-grafted patient with aplastic anaemia
- 1985
-
Ingår i: The Lancet. - 1474-547X. ; 325:8432, s. 778-781
-
Tidskriftsartikel (refereegranskat)abstract
- IgA deficiency developed in a 2-year-old boy with aplastic anaemia who received a bone-marrow graft from his HLA-identical, 6-year-old, IgA-deficient sister. Southern blot analysis revealed the presence of alpha-genes in both children, thus suggesting a defect of lymphocyte stem-cell differentiation as a cause of IgA deficiency. Tissue typing showed homozygosity of HLA A1, B8, DR3, the haplotype associated with IgA deficiency in healthy people. Despite normal serum levels of IgG subclasses in both donor and recipient, both children showed a relative lack of specific IgG2 anticarbohydrate antibodies. This suggests that their IgA deficiency is part of a more fundamental aberration of immunoglobulin class and subclass distribution.
|
|
| 6. |
- Löfstedt, Christer, et al.
(författare)
-
Diet related courtship success in the oriental fruit moth, Grapholita molesta (Tortricidae)
- 1989
-
Ingår i: Oikos. - : JSTOR. - 0030-1299. ; 55:3, s. 402-408
-
Tidskriftsartikel (refereegranskat)abstract
- Males reared on artificial diet as larvae or starved as adults contained lower amounts of the behaviourally most active courtship pheromone component ethyl trans-cinnamate, but no difference in mating success between apple-reared and diet-reared males could be demonstrated. -from Authors
|
|
| 7. |
- Shingler, V, et al.
(författare)
-
Analysis of nonpolar insertion mutations in the trfA gene of IncP plasmid RK2 which affect its broad-host-range property.
- 1989
-
Ingår i: Biochimica et Biophysica Acta. - 0006-3002 .- 1878-2434. ; 1007:3
-
Tidskriftsartikel (refereegranskat)abstract
- Replication of broad-host-range plasmid RK2 requires the protein product(s) of the plasmid-encoded trfA gene to initiate replication at oriV, the vegetative replication origin. The trfA gene contains two translational starts which direct translation of two polypeptides, of 382 and 285 amino acids, which differ by the 97 amino acids at their N-terminus. Nonpolar insertions which abolish expression of the larger TrfA polypeptide but otherwise retain the trfA gene's normal expression signals severely reduce plasmid replication efficiency in Pseudomonas aeruginosa and to a lesser extent in Pseudomonas putida, but have very little effect in Escherichia coli. This indicates that the organization of the trfA gene, producing two polypeptides products, plays an important part in the broad-host-range of plasmid RK2 by providing a degree of flexibility in the way the plasmid's replication system interacts with host biochemistry.
|
|
