Isolation and Molecular Characterization of Five Marine Cyanophages Propagated on Synechococcus sp. Strain WH7803

Five marine cyanophages propagated on Synechococcus sp. strain WH7803 were isolated from three different oceanographic provinces during the months of August and September 1992: coastal water from the Sargasso Sea, Bermuda; Woods Hole harbor, Woods Hole, Mass.; and coastal water from the English Channel, off Plymouth Sound, United Kingdom. The five cyanophage isolates were found to belong to two families, Myoviridae and Styloviridae, on the basis of their morphology observed in the transmission electron microscope. DNA purified from each of the cyanophage isolates was restricted with a selection of restriction endonucleases, and three distinguishably different patterns were observed. DNA isolated from Myoviridae isolates from Bermuda and the English Channel had highly related restriction patterns, as did DNA isolated from Styloviridae isolates from Bermuda and the English Channel. DNA isolated from the Myoviridae isolate from Woods Hole had a unique restriction pattern. The genome size for each of the Myoviridae isolates was ca. 80 to 85 kb, and it was ca. 90 to 100 kb for each of the Styloviridae isolates. Southern blotting analysis revealed that there was a limited degree of homology among all cyanophage DNAs probed, but clear differences were observed between cyanophage DNA from the Myoviridae and that from the Styloviridae isolates. Polypeptide analysis revealed a clear difference between Myoviridae and Styloviridae polypeptide profiles, although the major, presumably structural, protein in each case was ca. 53 to 54 kDa.

Point of purchase cigarette promotions before and after the Master Settlement Agreement: exploring retail scanner data

BACKGROUND

Evidence indicates that point of purchase (POP) advertising and promotions for cigarettes have increased since the Master Settlement Agreement (MSA). Retail promotions have the potential to offset the effects of cigarette tax and price increases and tobacco control programmes.

OBJECTIVE

To describe the trend in the proportion of cigarette sales that occur as part of a POP promotion before and after the MSA.

DESIGN

Scanner data were analysed on cigarette sales from a national sample of grocery stores, reported quarterly from 1994 through 2003. The proportion of total cigarette sales that occurred under any of three different types of POP promotions is presented.

RESULTS

The proportion of cigarettes sold under a POP promotion increased notably over the sample period. Large increases in promoted sales are observed following implementation of the MSA and during periods of sustained cigarette excise tax increases.

CONCLUSIONS

The observed pattern of promoted cigarette sales is suggestive of a positive relationship between retail cigarette promotions, the MSA, and state cigarette tax increases. More research is needed to describe fully the relationship between cigarette promotions and tobacco control policy.

Isolation of lysogenic staphylophage and its potential use as a treatment of methicillin-resistant Staphylococcus aureus surgical infections

Background

The aim was to develop a new cost-effective, accessible method for treating multidrug-resistant bacterial infections in which the possibility for emergence of resistant strains is greatly reduced. Methicillin-resistant Staphylococcus aureus (MRSA) surgical wound infection was used as a model for these studies.

Methods

A collection of lysogenic bacteriophage was made by isolating Staphylococcus-specific bacteriophage (staphylophage) from clinical MRSA samples from England, Bulgaria and Poland. The phage was selected and characterized according to host range, source, morphology and stability. Resistance profiles of the S. aureus isolates (SAIs) for 16 antibiotics, including methicillin, were determined.

Results

Some 86 per cent of the SAIs were multidrug resistant. When the 152 SAIs were incubated with eight different S. aureus cultivating strains 79 per cent produced at least one phage able to infect at least one of the cultivating strains. 72·4 per cent were able to infect two or more.

Conclusion

Lysogenic MRSA isolates are a characterizable, widely available source of staphylophage that can be used as an alternative to the traditional environmental sources. A specific pattern for geographical distribution of lysogenic staphylophage has been demonstrated which further facilitates the isolation process. The narrow host range of bacteriophage compared with chemotherapeutic agents ensures a minimal effect on non-pathogenic bacteria within the patient. This is an ongoing study and these are preliminary results. At the end of the study a method for isolation and development of therapeutic phage will be available for use in the industrial and hospital setting.

A conserved genetic module that encodes the major virion components in both the coliphage T4 and the marine cyanophage S-PM2

Sequence analysis of a 10-kb region of the genome of the marine cyanomyovirus S-PM2 reveals a homology to coliphage T4 that extends as a contiguous block from gene (g)18 to g23. The order of the S-PM2 genes in this region is similar to that of T4, but there are insertions and deletions of small ORFs of unknown function. In T4, g18 codes for the tail sheath, g19, the tail tube, g20, the head portal protein, g21, the prohead core protein, g22, a scaffolding protein, and g23, the major capsid protein. Thus, the entire module that determines the structural components of the phage head and contractile tail is conserved between T4 and this cyanophage. The significant differences in the morphology of these phages must reflect the considerable divergence of the amino acid sequence of their homologous virion proteins, which uniformly exceeds 50%. We suggest that their enormous diversity in the sea could be a result of genetic shuffling between disparate phages mediated by such commonly shared modules. These conserved sequences could facilitate genetic exchange by providing partially homologous substrates for recombination between otherwise divergent phage genomes. Such a mechanism would thus expand the pool of phage genes accessible by recombination to all those phages that share common modules.

Automated scoring of patient pain drawings using artificial neural networks: efforts toward a low back pain triage application

The goal of this research was to examine methods of automatically scoring patient pain drawings. Two hundred and fifty pain drawings were selected from the files of an orthopaedic surgeon who specializes in the treatment of low back pain patients. An artificial neural network was designed to score these drawings. The drawings were segmented into 85 regions following dermatomal mappings and from these regions the percent area in pain in each was computed and used as the neural network input variables. With five outcome categories (scores) we obtained a classification sensitivity of 49%, which is approximately as well as physician experts and discriminant analysis achieved using a subset of the same data. We conclude that an artificial neural network is well suited to automatically score patient pain drawings.

Involvement of an FtsH homologue in the assembly of functional photosystem I in the cyanobacterium Synechocystis sp. PCC 6803

The Synechocystis sp. PCC 6803 genome encodes four putative homologues of the AAA protease FtsH, two of which (slr0228 and sll1463) have been subjected to insertional mutagenesis in this study. Disruption of sll1463 had no discernible effect but disruption of slr0228 caused a 60% reduction in the abundance of functional photosystem I, without affecting the cellular content of photosystem II or phycobilisomes. Fluorescence and immunoblotting analyses show reductions in PS I polypeptides and possible structural alterations in the residual PS I, indicating an important role for slr0228 in PS I biogenesis.

Occurrence of a sequence in marine cyanophages similar to that of T4 g20 and its application to PCR-based detection and quantification techniques

Viruses are ubiquitous components of marine ecosystems and are known to infect unicellular phycoerythrin-containing cyanobacteria belonging to the genus Synechococcus. A conserved region from the cyanophage genome was identified in three genetically distinct cyanomyoviruses, and a sequence analysis revealed that this region exhibited significant similarity to a gene encoding a capsid assembly protein (gp20) from the enteric coliphage T4. The results of a comparison of gene 20 sequences from three cyanomyoviruses and T4 allowed us to design two degenerate PCR primers, CPS1 and CPS2, which specifically amplified a 165-bp region from the majority of cyanomyoviruses tested. A competitive PCR (cPCR) analysis revealed that cyanomyovirus strains could be accurately enumerated, and it was demonstrated that quantification was log-linear over ca. 3 orders of magnitude. Different calibration curves were obtained for each of the three cyanomyovirus strains tested; consequently, cPCR performed with primers CPS1 and CPS2 could lead to substantial inaccuracies in estimates of phage abundance in natural assemblages. Further sequence analysis of cyanomyovirus gene 20 homologs would be necessary in order to design primers which do not exhibit phage-to-phage variability in priming efficiency. It was demonstrated that PCR products of the correct size could be amplified from seawater samples following 100x concentration and even directly without any prior concentration. Hence, the use of degenerate primers in PCR analyses of cyanophage populations should provide valuable data on the diversity of cyanophages in natural assemblages. Further optimization of procedures may ultimately lead to a sensitive assay which can be used to analyze natural cyanophage populations both quantitatively (by cPCR) and qualitatively following phylogenetic analysis of amplified products.

Evaluation of preoperative patient education and computer-assisted patient instruction

Health care practitioners believe that patient education enhances patients' compliance with treatment, their medical outcomes, and their quality of life. This study evaluated an existing method of noncomputerized structured preoperative education delivered by a nurse specialist and implemented and evaluated a computer-assisted instruction (CAI) tool for nonsurgical patients in the Vanderbilt Orthopaedic Spine Service. These patient education modalities were assessed with regard to the patient health concepts measured in the Short Form-36 Health Survey and, in addition, for preoperative education, with regard to the length of patient hospital stay. Preoperative education improved patient perceptions of vitality and mental health, increased length of stay for discectomy patients, and had no effect on length of stay for other surgical procedures. CAI improved patient perceptions of bodily pain.

An immunological approach to detect phosphate stress in populations and single cells of photosynthetic picoplankton

In the marine cyanobacterium Synechococcus sp. strain WH7803, PstS is a 32-kDa cell wall-associated phosphate-binding protein specifically synthesized under conditions of restricted inorganic phosphate (P1) availability (D. J. Scanlan, N. H. Mann, and N. G. Carr, Mol. Microbiol. 10:181-191, 1993). We have assessed its use as a potential diagnostic marker for the P status of photosynthetic picoplankton. Expression of PstS in Synechococcus sp. strain WH7803 was observed when the P1 concentration fell below 50 nM, demonstrating that the protein is induced at concentrations of P1 typical of oligotrophic conditions. PstS expression could be specifically detected by use of standard Western blotting (immunoblotting) techniques in natural mesocosm samples under conditions in which the N/P ratio was artificially manipulated to force P depletion. In addition, we have developed an immunofluorescence assay that can detect PstS expression in single Synechococcus cells both in laboratory cultures and natural samples. We show that antibodies raised against PstS cross-react with P-depleted Prochlorococcus cells, extending the use of these antibodies to both major groups of prokaryotic photosynthetic picoplankton. Furthermore, DNA sequencing of a Prochlorococcus pstS homolog demonstrated high amino acid sequence identity (77%) with the marine Synechococcus sp. strain WH7803 protein, including those residues in Escherichia coli PstS known to be directly involved in phosphate binding.

Web client and ODBC access to legacy database information: a low cost approach

A new method has been developed for the Department of Orthopaedics of Vanderbilt University Medical Center to access departmental clinical data. Previously this data was stored only in the medical center's mainframe DB2 database, it is now additionally stored in a departmental SQL database. Access to this data is available via any ODBC compliant front-end or a web client. With a small budget and no full time staff, we were able to give our department on-line access to many years worth of patient data that was previously inaccessible.

Integrating and presenting clinical and treatment outcome data for cost-effective case management

The broad objective was to develop an information system which integrates various sources of clinical data and facilities outcome assessment for patients evaluated in a lumbar spine service. During a patient encounter, the physician formulates a hypothesis regarding appropriate forms of treatment and he or she may then use this system to explore previous treatment outcomes for similar cases. The availability of a clinical tool that presents information in an outcome-oriented format may be highly relevant to the delivery of cost-efficient, high-quality health care and also create a formal mechanism for detecting practice variability.

Characterization of the genes encoding a phosphate-regulated two component sensory system in the marine cyanobacterium Synechococcus sp. WH7803

An oligomer probe was designed to detect the presence of a putative phoB gene in the genome of the marine, phycoerythrin-containing cyanobacterium Synechococcus sp. WH7803. A 2.2 kb PstI fragment, identified using this probe, was cloned and the complete nucleotide sequence determined. The fragment contained two open reading frames encoding polypeptides which display all the sequence features expected of the response regulator and histidine protein kinase elements of a two component sensory system. Northern analysis confirmed that transcription of these genes was induced by phosphate limitation. On the basis of the sequence similarities and the regulation of their transcription by the availability of inorganic phosphate (Pi) these open reading frames were designated as phoB and phoR, respectively.

Identification of iron superoxide dismutase and a copper/zinc superoxide dismutase enzyme activity within the marine cyanobacterium Synechococcus sp. WH 7803

Three constitutive forms of superoxide dismutase activity have been demonstrated in the cyanobacterial marine picoplankter Synechococcus sp. WH 7803 using polyacrylamide gel activity staining techniques. A protein which gave a positive non-haem iron stain on native polyacrylamide gels exhibited N-terminal similarity to both the iron superoxide dismutase and the manganese superoxide dismutase of Escherichia coli. The metal prosthetic group of each of the three activity bands was characterised by analysing their differential sensitivities to 5 mM H2O2, 2 mM cyanide and 2 mM of the copper chelator diethyldithiocarbamate. Three distinct superoxide dismutase activities were observed, an iron superoxide dismutase, a copper/zinc superoxide dismutase and a third form which has not been identified. Growth of Synechococcus cells in ASW medium containing no added iron resulted in no alteration in the activity of the iron superoxide dismutase. Growth of cultures in the absence of copper or zinc resulted in differential changes in the activities of the copper/zinc superoxide dismutase and the unidentified superoxide dismutase.

A comparison of gene organization in the zwf region of the genomes of the cyanobacteria Synechococcus sp. PCC 7942 and Anabaena sp. PCC 7120

The region of the genome encoding the glucose-6-phosphate dehydrogenase gene zwf was analysed in a unicellular cyanobacterium, Synechococcus sp. PCC 7942, and a filamentous, heterocystous cyanobacterium, Anabaena sp. PCC 7120. Comparison of cyanobacterial zwf sequences revealed the presence of two absolutely conserved cysteine residues which may be implicated in the light/dark control of enzyme activity. The presence in both strains of a gene fbp, encoding fructose-1,6-bisphosphatase, upstream from zwf strongly suggests that the oxidative pentose phosphate pathway in these organisms may function to completely oxidize glucose 6-phosphate to CO2. The amino acid sequence of fructose-1,6-bisphosphatase does not support the idea of its light activation by a thiol/disulfide exchange mechanism. In the case of Anabaena sp. PCC 7120, the tal gene, encoding transaldolase, lies between zwf and fbp.

ADP-ribosylation of glutamine synthetase in the cyanobacterium Synechocystis sp. strain PCC 6803

Glutamine synthetase (GS) inactivation was observed in crude cell extracts and in the high-speed supernatant fraction from the cyanobacterium Synechocystis sp. strain PCC 6803 following the addition of ammonium ions, glutamine, or glutamate. Dialysis of the high-speed supernatant resulted in loss of inactivation activity, but this could be restored by the addition of NADH, NADPH, or NADP+ and, to a lesser extent, NAD+, suggesting that inactivation of GS involved ADP-ribosylation. This form of modification was confirmed both by labelling experiments using [32P]NAD+ and by chemical analysis of the hydrolyzed enzyme. Three different forms of GS, exhibiting no activity, biosynthetic activity only, or transferase activity only, could be resolved by chromatography, and the differences in activity were correlated with the extent of the modification. Both biosynthetic and transferase activities were restored to the completely inactive form of GS by treatment with phosphodiesterase.

Characterization of a zwf mutant of Synechococcus sp. strain PCC 7942

A mutant of the cyanobacterium Synechococcus sp. strain PCC 7942 carrying a disrupted gene encoding glucose-6-phosphate dehydrogenase (zwf) produced no detectable glucose-6-phosphate dehydrogenase as assessed by enzyme assay and Western blot (immunoblot) analysis. This mutant exhibited significantly impaired dark viability.

Organization and transcription of the class I phycoerythrin genes of the marine cyanobacterium Synechococcus sp. WH7803

The nucleotide sequences of the class I phycoerythrin (PE) alpha- and beta-subunit genes (cpeA and cpeB) from the marine cyanobacterium Synechococcus sp. WH7803 are reported. The cpeB gene is located upstream of cpeA with a separation of 56 nucleotides and the two genes are co-transcribed as a transcript of 1.3 kb, with the transcription startpoint being localized to 110-111 bp upstream of cpeB. The sequence of the promoter region bears no similarity to promoters reported for other cyanobacterial PE genes. Pentanucleotide repeats found upstream of some PE operons, particularly in the case of cyanobacterial strains capable of chromatic adaption, are not found in Synechococcus sp. WH7803; instead the sequence 5'-CGGTT-3' is repeated three times in the promoter region.

The response of the picoplanktonic marine cyanobacterium Synechococcus species WH7803 to phosphate starvation involves a protein homologous to the periplasmic phosphate-binding protein of Escherichia coli

During phosphate-limited growth the marine phycoerythrin-containing picoplanktonic cyanobacterium Synechococcus sp. WH7803 synthesizes novel polypeptides, including two abundant species of 100 kDa and 32 kDa. The 32 kDa polypeptide was localized to the cell wall, although in a related strain, Synechococcus sp. WH8103, it could be detected in both the cell wall fraction and the periplasm. The gene (designated pstS) encoding this polypeptide was cloned and shown to be present in a single copy. The deduced amino acid sequence indicated a polypeptide consisting of 326 amino acids with a calculated M(r) of 33,763. Comparison of this sequence with that obtained by microsequencing the N-terminus of the 32 kDa polypeptide showed that the mature protein was synthesized as a precursor, the first 24 amino acid residues being cleaved between two alanine residues at positions 24 and 25. The amino acid sequence of the mature polypeptide showed 35% identity and 52% similarity to the periplasmic phosphate-binding protein (PstS) from Escherichia coli, including three regions of much stronger homology which, by comparison with E. coli PstS, are directly involved in phosphate binding. Northern blot analysis revealed a pstS transcript of 1.2 kb in RNA extracted from cells grown in Pi-replete conditions and one of 1.4 kb in considerably increased abundance under Pi-depleted conditions. Homologues of the pstS gene were detected in other marine phycoerythrin-containing Synechococcus strains, but not in freshwater or halotolerant species.

ATP induces large quaternary rearrangements in a cage-like chaperonin structure

BACKGROUND

The chaperonins, a family of molecular chaperones, are large oligomeric proteins that bind nonnative intermediates of protein folding. They couple the release and correct folding of their ligands to the binding and hydrolysis of ATP. Chaperonin 60 (cpn60) is a decatetramer (14-mer) of 60 kD subunits. Folding of some ligands also requires the cooperation of cpn10, a heptamer of 10 kD subunits.

RESULTS

We have determined the three-dimensional arrangements of subunits in Rhodobacter sphaeroides cpn60 in the nucleotide-free and ATP-bound forms. Negative stain electron microscopy and tilt reconstruction show the cylindrical structure of the decatetramer comprising two rings of seven subunits. The decatetramer consists of two cages joined base-to-base without a continuous central channel. These cages appear to contain bound polypeptide with an asymmetric distribution between the two rings. The two major domains of each subunit are connected on the exterior of the cylinder by a narrower bridge of density that could be a hinge region. Binding of ATP to cpn60 causes a major rearrangement of the protein density, which is reversed upon the hydrolysis of the ATP. Cpn10 binds to only one end of the cpn60 structure and is visible as an additional layer of density forming a cap on one end of the cpn60 cylinder.

CONCLUSIONS

The observed rearrangement is consistent with an inward 5-10 degrees rotation of subunits, pivoting about the subunit contacts between the two heptamers, and thus bringing cpn60 domains towards the position occupied by the bound polypeptide. This change could explain the stimulation of ATPase activity by ligands, and the effects of ATP on lowering the affinity of cpn60 for ligands and on triggering the release of folding polypeptides.

Initial-impression diagnosis using low-back pain patient pain drawings

Patient pain drawings were blindly selected from five lumbar spine disorder categories. The drawings were classified by low-back physicians, discriminant analysis, and several computerized artificial neural network configurations. The purpose was to determine the reliability of the patient pain drawing when diagnosing low-back disorders and to delineate the pain mark patterns particular to each disorder by comparing physicians with computerized methods. The physicians averaged 51% accuracy with individual preferences for certain disorder groups. The computerized methods demonstrated comparable accuracy (48%) and more agreement in classification. Associations were found between the predicted pain patterns for each diagnostic group made by an expert and the patterns generated by computerized methods. Variances in these associations are instructive to clinicians for making accurate predictions of diagnosis from pain drawings.

Expert performance in low-back disorder recognition using patient pain drawings

Eight low-back-pain experts who regularly include pain drawings in their clinical workup were asked to classify 25 drawings. The experts used only the drawings to place cases into one of five broadly defined diagnostic categories: benign disorder, herniated disc, spinal stenosis, underlying disorder, or psychogenic disturbance. The physicians demonstrated adequate accuracy--51% correct--when compared with change (20% correct). Classification accuracy was greatest for psychogenic disorders (85%), followed by spinal stenosis (58%), herniated discs (52%), and benign disorders (50%). Predictions were comparatively poor for the underlying disorder category (10%). The individual physician accuracies varied from 44 to 60%. "Classic" pain patterns for each disorder group were identified by determining which drawings were correctly classified by most physicians. Physicians may wish to impart greater significance to pain drawings close to one of our "classic" patterns than to others.

Bicarbonate Concentration by Synechocystis PCC6803 : Modulation of Protein Phosphorylation and Inorganic Carbon Transport by Glucose

The ability of the cyanobacterium Synechocystis PCC6803 to transport inorganic carbon in the form of bicarbonate rapidly decreased following a shift from bicarbonate-limited growth to either excess bicarbonate supply or to photoheterotrophic growth on glucose. Nonmetabolizable analogs of glucose did not exert this effect. The rate at which the bicarbonate uptake rate declined was too rapid to be accounted for by dilution of the activity by culture growth and suggested that posttranslational modification may be involved. Several proteins that were unphosphorylated during bicarbonate-limited growth became phosphorylated during the shifts to high CO(2) conditions and to photoheterotrophic growth. A similar alteration in the profile of phosphopolypeptides was observed following a shift into the dark. The changes in protein phosphorylation were not blocked by chloramphenicol or rifampicin.

Artificial intelligence in the diagnosis of low back pain

Computerized methods are used to recognize the characteristics of patient pain drawings. Artificial neural network (ANN) models are compared with expert predictions and traditional statistical classification methods when placing the pain drawings of low back pain patients into one of five clinically significant categories. A discussion is undertaken outlining the differences in these classifiers and the potential benefits of the ANN model as an artificial intelligence technique.

Characterization and sequence analysis of a small plasmid from Bacillus thuringiensis var. kurstaki strain HD1-DIPEL

The complete nucleotide sequence of a small (2.055 kb) plasmid pHD2 from Bacillus thuringiensis var. kurstaki strain HD1-DIPEL was obtained. The sequence encoded two open reading frames (ORFs) which corresponded to polypeptides of Mr 26,447 and 9122. Comparison of the sequence with those obtained for other plasmids from Gram-positive organisms suggested that pHD2 may belong to the extensive and highly interrelated family of plasmids exhibiting replication via a ssDNA intermediate: a putative nick site was proposed on the basis of sequence homology and one ORF exhibited distant homology with the site-specific topoisomerases encoded by the pT181 family of staphylococcal plasmids, while the other ORF exhibited considerable similarity to a small polypeptide (RepA) encoded by plasmid pLS1. Constructs consisting of pHD2, pBR322, and the chloramphenicol resistance gene from pC194 were capable of stable maintenance in B. thuringiensis var. israelensis, but were subject to apparently specific deletions in the heterologous host. The same constructs could not be established in Bacillus subtilis.

Statistical diagnosis of lumbar spine disorders using computerized patient pain drawings

Discriminant analysis is applied to 250 quantified low back patient pain drawings to study the ability of a computerized statistical method for classifying novel cases into one of five clinically-significant lumbar spine disorders. Tests on independent data were 46.2 percent (%) correct overall. Benign disorder (55.6%), herniated disc (51.7%), and psychogenic (56.3%) pain drawings were more accurately discriminated than the spinal stenosis (32.2%) and underlying disorder cases (35.2%). It is concluded that computerized patient pain drawings provide valid "initial impressions" of lumbar spine disorders. Further research is suggested to better distinguish between herniated disc and spinal stenosis pain descriptions, and for better recognition of serious underlying disorder pain drawings.

Identification and characterization of a GroEL homologue in Rhodobacter sphaeroides

A protein closely related to the Escherichia coli GroEL protein has been isolated from Rhodobacter sphaeroides. Native and SDS-polyacrylamide gel electrophoresis of this protein have shown that it is present in the cell as a multimeric complex of Mr 670,000 which is composed of a monomer of Mr 58,000. Antisera raised against the Mr 58,000 polypeptide have been shown to cross-react with GroEL and the alpha subunit of the pea plastid chaperonin. The N-terminal amino acid sequence of the Mr 58,000 polypeptide is identical to that of GroEL at 15 of 19 residues and is also closely related to the alpha subunit of the pea plastid chaperonin, though less so to the beta subunit.

Construction of lacZ promoter probe vectors for use in Synechococcus: application to the identification of CO2-regulated promoters

It was shown that the Escherichia coli lacZ gene could be expressed in the cyanobacterium Synechococcus R2 PCC7942 both as a plasmid-borne form and also integrated into the chromosome. A promoterless form of the lacZ gene was constructed and used as a reporter gene to make transcriptional fusions with cyanobacterial promoters using a shuttle vector system and also via a process of integration by homologous recombination. Synechococcus R2 promoter-lacZ gene fusions were then used to identify CO2-regulated promoters, by quantitatively assessing beta-galactosidase activity under high and low CO2 conditions using a fluorescence assay. Several promoters induced under low CO2 conditions were detected.

Protein kinase activities in cell-free extracts of Streptomyces coelicolor A3(2)

Protein kinase activities were detected in cell-free extracts of the B385 derivative of Streptomyces coelicolor A3(2); at least 12 polypeptides, ranging in Mr from 6,000 to 98,000, were detectably phosphorylated, probably as O-monoesters, after incubation with gamma [32P]ATP. The culture stage of the mycelia used for production of the cell-free extracts determined the profile of phosphorylated polypeptides. Phosphoenol pyruvate acted as a potent modulator of the apparent degree of protein kinase activity. In addition Ca2+ ions, verapamil, chlorpromazine and anti-calmodulin antiserum had specific effects on the profile of phosphopolypeptides observed.

Cloning and expression in Escherichia coli of the toluene dioxygenase gene from Pseudomonas putida NCIB11767

The genes encoding toluene dioxygenase, toluene cis-glycol dehydrogenase and catechol 2.3-oxygenase from Pseudomonas putida NCIB 11767 were cloned and expressed in Escherichia coli HB101 on a 20 kb fragment. The recombinant strain produced indigo and a variety of other coloured products. Although the enzymes were expressed in the absence of inducers, further induction was observed in the presence of toluene or benzene, implying the presence of regulatory elements on the 20 kb insert.

Protein phosphorylation in Bacillus thuringiensis during growth and delta-endotoxin production

At least 14 phosphopolypeptides in which the phosphate groups were present as mono-esters were detected by pulse labelling of Bacillus thuringiensis subsp. kurstaki HD-1-Dipel with [32P]orthophosphate at different stages of growth and differentiation. Marked changes in the profile of phosphopolypeptides were observed primarily during the late exponential phase of growth. Several phosphopolypeptides co-purified with the endotoxin crystal of this subspecies and the phosphoamino acid residue of the most abundant (Mr 25,000) phosphopolypeptide was identified as phosphothreonine. Comparison of the phosphopolypeptides in endotoxin crystals from several subspecies suggested that Mr 25,000 species might be a common component.

Covalent modification of ribulose 1,5-bisphosphate carboxylase/oxygenase in Rhodomicrobium vannielii

The most abundant phosphorus-containing polypeptide in the purple non-sulphur bacterium Rhodomic-robium vannielii has been identified by a combination of immunoprecipitation and sucrose density gradient centrifugation as the large subunit of ribulose 1,5-bisphosphate carboxylase/oxygenase. The covalent modification of the large subunit involves the phosphorylation of one or more tyrosine residues and appears to occur prior to assembly of the large subunit into the mature enzyme. In addition, the phosphorylated form of the large subunit was found to exist in at least two distinct protein complexes of Mr 410,000 and 440,000.

Analysis of inverted repeat DNA in the genome of Rhodomicrobium vannielii

The DNA of Rhodomicrobium vannielii was analysed for the presence of inverted repeat sequences (IR DNA) by S1 nuclease digestion. Approximately 7% of chromosomal DNA was found to be IR DNA which comprised two size classes. The large IR DNA was heterogeneous and contained species in the size range 100-700 bp. The smaller size class contained species of 17 and 27 bp. Both size classes of IR DNA hybridized to many chromosomal restriction fragments, suggesting that these IR DNA sequences are dispersed throughout the genome. Hybridization studies also indicated sequence homology between the two classes of IR DNA and suggested that the 17 and 27 bp IR DNA sequences may exist in clusters.

Plasmid partitioning in Escherichia coli

The mechanisms by which plasmids are stably maintained in bacterial populations are not yet completely understood. However, it is apparent that interactions with the cell envelope, site-specific recombination and modulation of the host cell's division process may be involved in plasmid maintenance.

Cloning of a Bacillus subtilis restriction fragment complementing auxotrophic mutants of eight Escherichia coli genes of arginine biosynthesis

Following shotgun cloning of EcoRI fragments of Bacillus subtilis 168 chromosomal DNA in pBR322 a hybrid plasmid, pUL720, was isolated which complements Escherichia coli K12 mutants defective for argA, B, C, D, E, F/I, carA and carB. Restriction analysis revealed that the insert of pUL720 comprises four EcoRI fragments, of sizes 12.0, 6.0, 5.0 and 0.8 kbp. Evidence was obtained from subcloning, Southern blot hybridisation, enzyme stability studies and transformation of B. subtilis arginine auxotrophs that the 12 kbp EcoRI fragment carries all the arg genes. It proved impossible to subclone the intact fragment in isolation in the multicopy vectors pBR322, pBR325 or pACYC184, and although it could be subcloned in the low copy vector pGV1106, propagation of the hybrid rapidly resulted in the selection of stable derivatives carrying, near one end, an insertion of 1 kbp of DNa originating from the E. coli chromosome. These and other stable derivatives resulting from subcloning the 12 kbp EcoRI fragment have lost only the ability to complement for E. coli argC, and it is suggested that sequences located close to the equivalent of argC are involved in destabilising plasmids bearing the 12 kbp fragment in E. coli in a copy number dependent manner.

Transcription analysis of a Bacillus subtilis arg gene following cloning in Escherichia coli in an initially unstable hybrid plasmid

Following shotgun cloning of EcoRI fragments of Bacillus subtilis DNA in pBR322, a hybrid plasmid pUL710 was isolated which complements argC but no other auxotrophs of E. coli K12. Restriction mapping, Southern blotting and other evidence suggest that pUL710 carries an insert of 1.6 kbp, and derives, by deletion of both vector and insert sequences, from a larger but unstable initial hybrid which carried a 12 kbp EcoRI fragment from the B. subtilis chromosome. RecE-dependent integration of pUL710 into the B. subtilis chromosome demonstrated homology between the insert DNA and the argO locus of B. subtilis. pUL710 was found to confer appreciable tetracycline resistance even though the deletion presumed to stabilise the hybrid had inactivated the tet promoter. The results of analysis by Tn5 mutagenesis, transcriptional fusions and run-off in vitro transcription suggest that both the cloned argC gene and the tetracycline gene in pUL710 are expressed from a B. subtilis promoter located very close to the EcoRI cloning site.