Correction to: Comparative analysis of confocal microscopy on fresh breast core needle biopsies and conventional histology

Following publication of the original article [1], the authors reported an added data on Table 1 in their paper. The original article [1] has been updated.

Comparative analysis of confocal microscopy on fresh breast core needle biopsies and conventional histology

Background

Evaluation of core needle biopsies (CNB) is a standard procedure for the diagnosis of breast cancer. However, tissue processing and image preparation is a time- consuming procedure and instant on-site availability of high-quality images could substantially improve the efficacy of the diagnostic procedure. Conventional microscopic methods, such as frozen section analysis (FSA) for detection of malignant cells still have clear disadvantages. In the present study, we tested a confocal microscopy scanner on fresh tissue from CNB with intention to develop an alternative device to FSA in clinical practice.

Patients and methods

In 24 patients with suspicious breast lesions standard of care image-guided biopsies were performed. Confocal images have been obtained using the Histolog™ Scanner and evaluated by two independent pathologists. Hematoxylin-Eosin (H&E) histological sections of the biopsies were routinely processed in a blinded fashion with respect to the confocal images.

Results

In total 42 confocal images were generated from 24 biopsy specimens, and available for analysis within a few minutes of taking the biopsy. This resulted in 2 × 42 = 84 pathologic evaluations. In four cases, a pathologic diagnosis was not possible with confocal microscopy. An exact correlation based on the B-classification was reached in 41 out of 80 examinations and in another 35 cases in a broader sense of correspondence definition (i.e. malignant vs. benign).

Conclusions

As a reliable on-site method, the Histolog™ Scanner provides a visualization of cellular details equivalent to the H&E standards, permitting rapid and accurate diagnosis of malignant and benign breast lesions. Furthermore, this device offers great potential for immediate margin analysis of specimen in breast conserving therapy.

Disease-related surgery in patients with distant metastatic breast cancer

INTRODUCTION

This study evaluates the frequency of and indications for disease-related surgical procedures in the palliative breast cancer (BC) situation.

PATIENTS & METHODS

Based on a cohort of women who were treated for newly diagnosed BC during a 20-year period (1990-2009), we analyzed 340 patients who developed distant metastatic disease (DMD) until 2011 and died (i.e. still ongoing palliative disease courses were not included).

RESULTS

One hundred and twenty-seven surgical procedures were performed in 100 patients (29.4% of all patients with metastatic disease). The most common site for surgery was breast (n = 60, 47.2%). The primary tumor was removed at first diagnosis of DMD in 43 patients (33.9%); sixteen operations (12.6%) were performed for local recurrence. In 37 patients, 50 surgical procedures (39.4%) were necessary to stabilize osseous structures due to metastases. Procedures were rarely performed on other common metastatic sites: lung: n = 1 (0.8%); liver: n = 1 (0.8%), brain: n = 4 (3.1%). When excluding surgery for primary breast tumors at initial diagnosis of DMD from analysis, 34 of 84 surgeries (40.4%) were performed in the first third of survival follow-up (i.e. period of metastatic disease survival); operations in the last two-thirds each totaled 29.8% (n = 25). The median survival after surgery was 16 months (range: 0.5-89 months).

CONCLUSIONS

In a cohort of BC patients who had primary or developed secondary DMD, nearly one third of the patients received disease-related surgical procedures during their palliative disease course. This high rate of operations shows that surgery has a clearly established role in the palliative therapy concept.

Content comparison of health status measures for obesity based on the international classification of functioning, disability and health

OBJECTIVE

To compare the content covered by twelve obesity-specific health status measures using the International Classification of Functioning, Disability and Health (ICF).

DESIGN

Obesity-specific health status measures were identified and then linked to the ICF separately by two trained health professionals according to standardized guidelines. The degree of agreement between health professionals was calculated by means of the kappa (kappa) statistic. Bootstrapped confidence intervals (CI) were calculated. The obesity-specific health-status measures were compared on the component and category level of the ICF.

MEASUREMENTS

welve condition-specific health-status measures were identified and included in this study, namely the obesity-related problem scale, the obesity eating problems scale, the obesity-related coping and obesity-related distress questionnaire, the impact of weight on quality of life questionnaire (short version), the health-related quality of life questionnaire, the obesity adjustment survey (short form), the short specific quality of life scale, the obesity-related well-being questionnaire, the bariatric analysis and reporting outcome system, the bariatric quality of life index, the obesity and weight loss quality of life questionnaire and the weight-related symptom measure.

RESULTS

In the 280 items of the eight measures, a total of 413 concepts were identified and linked to the 87 different ICF categories. The measures varied strongly in the number of concepts contained and the number of ICF categories used to map these concepts. Items on body functions varied form 12% in the obesity-related problem scale to 95% in the weight-related symptom measure. The estimated kappa coefficients ranged between 0.79 (CI: 0.72, 0.86) at the component ICFs level and 0.97 (CI: 0.93, 1.0) at the third ICF's level.

CONCLUSION

The ICF proved highly useful for the content comparison of obesity-specific health-status measures. The results may provide clinicians and researchers with new insights when selecting health-status measures for clinical studies in obesity.

Up to 21-day banked red blood cells collected by apheresis and stored for 14 days after automated wash at different times of storage

BACKGROUND AND OBJECTIVES

A closed-system technology (ACP-215, Haemonetics, Braintree, MA) enables automated washing and extended storage of frozen red blood cells (RBC). This technology was applied to wash banked RBC for removal of undesirable protein and metabolites before transfusion. We studied protein and metabolite depletion as well as RBC metabolism and viability up to 14 days postwash with regard to various pre-storage times.

MATERIALS AND METHODS

Thirty RBC units were collected by means of apheresis and subdivided into three arms based on prewash storage time period (6 days/group 1, 14 days/group 2, 21 days/group 3). Wash efficacy (protein depletion, IgA), RBC metabolism (pH, lactate, potassium, haemolysis) and cell viability (ATP) were analysed immediately and 14 days after washing.

RESULTS

Total protein and IgA postwash were lowered by automated wash in all groups and uniformly met EC guidelines. Potassium (mmol/l) was below 1.2 mmol/l postwash and significantly below prewash values in all groups, even after 14 days of storage (prewash vs. postwash; P < 0.05). RBCs washed after 14 and 21 days, respectively, showed significantly lower pH values and lower ATP content than RBCs washed after only 6 days of storage. Haemolysis rate remained significantly below 0.8%, the maximum level recommended by the EC guidelines, immediately and 14 days after washing in all units.

CONCLUSION

Our data confirm that RBC units banked up to 21 days can be effectively protein- and potassium-depleted with the ACP-215 independent from prewash storage time. With respect to high ATP levels and pH, postwash storage of 2 weeks should be limited to units not older than 7 days before wash. This new washing technology ensures better standardization in washed RBC and provides blood centres with a logistical alternative to 24-h washed RBC products.

Linking osteoarthritis-specific health-status measures to the International Classification of Functioning, Disability, and Health (ICF)

OBJECTIVES

The objective of this study was to link the Western Ontario and McMaster Universities (WOMAC) and Lequesne-Algofunctional indices to the ICF on the basis of linking rules developed specifically to accomplish this aim. The linking process enables the understanding of the relationship between health-status measures and the ICF.

METHODS

Since the fifth World Health Organisation/International Liege Against Rheumatism (WHO/ILAR) Task Force and the Outcome Measures in Rheumatology Clinical Trials (OMERACT) group recommend the use of WOMAC and the Lequesne-Algofunctional indices in patients with osteoarthritis of the hip and knee in clinical trials, these two health-status measures have been used in this study. Both health-status measures were linked to the ICF separately by two trained health professionals. Consensus between health professionals was used to decide which ICF category should be linked to each item/concept of the two questionnaires. To resolve disagreements between the two health professionals, a third person trained in the linking rules was consulted.

RESULTS

Except for the concept of 'morning stiffness', both health professionals agreed on the ICF category chosen to link all the items/concepts of both questionnaires. Altogether, 29 different ICF categories have been linked. Five ICF categories belong to the ICF component 'body functions', 23 categories to the component 'activities and participation', and one category to 'environmental factors'. Both questionnaires have 10 ICF categories in common.

CONCLUSIONS

The results of the linking process reflect both the structure of the two questionnaires studied and the relationship between them, showing that the ICF classification can become the cardinal reference for existing health-status measures.

Mucin 7 and cytokeratin 20 as new diagnostic urinary markers for bladder tumor

PURPOSE

We determine the sensitivity and specificity of cytokeratin 20 (CK-20) and mucin 7 (MUC7) gene expression in voided urine samples taken from patients with bladder tumor and from control groups to investigate putative, noninvasive urinary markers for bladder tumor detection and monitoring.

MATERIALS AND METHODS

Voided urine samples were collected from 50 patients with histologically proven bladder neoplasms (pTaN0M0G1-3 in 19 and pTisN0M0G3-pT4pN1M1G3 in 31), 20 patients with urolithiasis, 20 patients with urinary tract infection, 20 patients with other urological neoplasms and 20 healthy volunteers. Total RNA was extracted from exfoliated cells collected from 200 ml. voided urine. All RNA samples were investigated by a specific CK-20 and MUC7 nested reverse transcriptase polymerase chain reaction.

RESULTS

The overall sensitivity of CK-20 gene expression in voided urine samples for the detection of bladder neoplasms was 78%. In contrast, voided urine samples from control patients and healthy volunteers showed a high rate of false-positive CK-20 detection resulting in a low specificity of 36%. The overall sensitivity of the MUC7 test for all bladder tumor cases was 66%. The sensitivity for papillary urothelial neoplasms (pTaN0M0G1-3) was 42% whereas analysis of the carcinoma in situ and invasive bladder cancer group (pTisN0M0G3-pT4pN1M1G3) yielded a sensitivity of 81%. The overall specificity of the MUC7 nested reverse transcriptase polymerase chain reaction method in the control groups was 80%.

CONCLUSIONS

A high positive CK-20 detection rate was found not only in voided urine samples from patients with bladder tumor, but also in urine specimens from control groups. Therefore, CK-20 is not a reliable urinary tumor marker for bladder neoplasms. In contrast to CK-20, analysis of MUC7 demonstrated a high sensitivity and high specificity for carcinoma in situ and invasive bladder cancer, thus fulfilling the criteria of a urinary tumor marker.

Mucin 7 and cytokeratin 20 as new diagnostic urinary markers for bladder tumor

PURPOSE

We determine the sensitivity and specificity of cytokeratin 20 (CK-20) and mucin 7 (MUC7) gene expression in voided urine samples taken from patients with bladder tumor and from control groups to investigate putative, noninvasive urinary markers for bladder tumor detection and monitoring.

MATERIALS AND METHODS

Voided urine samples were collected from 50 patients with histologically proven bladder neoplasms (pTaN0M0G1-3 in 19 and pTisN0M0G3-pT4pN1M1G3 in 31), 20 patients with urolithiasis, 20 patients with urinary tract infection, 20 patients with other urological neoplasms and 20 healthy volunteers. Total RNA was extracted from exfoliated cells collected from 200 ml. voided urine. All RNA samples were investigated by a specific CK-20 and MUC7 nested reverse transcriptase polymerase chain reaction.

RESULTS

The overall sensitivity of CK-20 gene expression in voided urine samples for the detection of bladder neoplasms was 78%. In contrast, voided urine samples from control patients and healthy volunteers showed a high rate of false-positive CK-20 detection resulting in a low specificity of 36%. The overall sensitivity of the MUC7 test for all bladder tumor cases was 66%. The sensitivity for papillary urothelial neoplasms (pTaN0M0G1-3) was 42% whereas analysis of the carcinoma in situ and invasive bladder cancer group (pTisN0M0G3-pT4pN1M1G3) yielded a sensitivity of 81%. The overall specificity of the MUC7 nested reverse transcriptase polymerase chain reaction method in the control groups was 80%.

CONCLUSIONS

A high positive CK-20 detection rate was found not only in voided urine samples from patients with bladder tumor, but also in urine specimens from control groups. Therefore, CK-20 is not a reliable urinary tumor marker for bladder neoplasms. In contrast to CK-20, analysis of MUC7 demonstrated a high sensitivity and high specificity for carcinoma in situ and invasive bladder cancer, thus fulfilling the criteria of a urinary tumor marker.

A new tumour marker assay for ovarian cancer on the OPUS immunoassay system

The human tumour associated cancer antigen CA 125 is a glycoprotein with high molecular weight. The determination of this antigen has been proven to be useful in the monitoring of patients with ovarian cancer. OPUS OV, the tumour marker assay for the ovarian cancer antigen CA 125 is an ELISA that was developed for the family of fully automated random-access analyzers, OPUS, OPUS Plus and OPUS I Magnum. The assay uses a double monoclonal sandwich format (antibodies B27.1 and B43.13, Biomira/Canada). The first antibody is immobilized on the solid phase of the OPUS modules. Sample is automatically added and incubated for 5 minutes. The addition of a solution of the second antibody conjugated to the enzyme alkaline phosphatase leads to the formation of a sandwich complex within 5 minutes. The last step, the addition of the fluorogenic substrate 4-methylumbelliferyl phosphate, serves both as washing procedure and for the development of the fluorescence signal (kinetic measurement). OPUS OV has an assay range from 0-1000 kU/L with a detection limit of 5 kU/L. Within run cv's are 6-8%. A good correlation was found to commercially available kits for the determination of CA 125. We conclude that this new OPUS OV assay is a valid alternative for use in the routine determination of the cancer associated antigen CA 125 and allows more reliable determinations in terms of random access, speed, and ease of operation.

Expression and characterization of murine osteoblast-specific factor 2 (OSF-2) in a baculovirus expression system

Osteoblast-specific factor 2 (OSF-2) is a approximately 90-kDa protein selectively expressed in bone. OSF-2 cDNA was recently isolated from mouse and human cDNA libraries and shows limited sequence homology with fasciclin I, a cell adhesion protein expressed in insect nerve cells. Here we describe the expression of recombinant murine OSF-2 (rmOSF-2) in a baculovirus/insect cell system. Western blotting analysis employing polyclonal antiserum raised against a C-terminal synthetic OSF-2 peptide detected a protein of approximately 90-kDa as early as 2 days after infection of Sf9 cells with the recombinant virus. Tunicamycin treatment of infected cells resulted in a mobility shift of OSF-2 (approximately 90-kDa band) on Western blots. N-Glycanase digestion resulted in the same mobility shift of OSF-2, indicating that rmOSF-2 expressed in insect cells is N-glycosylated. However, OSF-2 was insensitive to endoglycosidase H digestion while a major fraction of this protein had affinity for concanavalin A. Finally, it was demonstrated that rmOSF-2 was able to bind to heparin. This finding suggests that OSF-2 might be associated with the bone extracellular matrix after secretion by osteoblasts and participate in cell adhesion and/or cell communication. The establishment of the baculovirus expression system with a high productivity of recombinant OSF-2 (around 40 micrograms/ml at maximum) and its heparin binding properties should allow us to obtain large amounts of rmOSF-2.

Sequences of two porcine glutamic acid decarboxylases (65- and 67-kDa GAD)

The cDNAs encoding the porcine 65- and 67-kDa glutamic acid decarboxylases (GAD65 and GAD67, respectively) were cloned by the PCR method. The 2246-nucleotide (nt) GAD65 cDNA contained an open reading frame (ORF) coding for a protein of 585 amino acids (aa), and the 3262-nt GAD67 cDNA contained an ORF coding for a protein of 594 aa. A remarkable conservation was shown when the deduced aa sequences of porcine GAD65 and GAD67 were compared with those of other mammalian species (human, cat and rat). Porcine GAD65 is 96% identical to human and rat GAD65, and porcine GAD67 is more than 95% identical to human, cat and rat GAD67 at the aa level.

Survival of genetically-engineered and wild-type strains of the yeast Saccharomyces cerevisiae under simulated environmental conditions: a contribution on risk assessment

A genetically-engineered strain of Saccharomyces cerevisiae employed for the industrial production of the human coagulation Factor XIIIa (rhFXIIIa) was used for a survival study under simulated environmental conditions. The homologous strain devoid of the recombinant plasmid and the homologous strain bearing the 2 microns-based vector plasmid without the rhFXIIIa-encoding DNA insert were compared. The strains were introduced into natural soil/water suspension, into soil/medium suspension and into waste water. After intervals, samples of cell suspensions were taken and viable cell numbers were determined by plating on antibiotic-containing medium. In addition, a non-radioactive technique involving enhanced chemiluminescence was employed to detect plasmid-bearing yeast cells. The rhFXIIIa expression plasmid showed a high stability during the simulated environmental condition. No differences in survival rates, however, could be detected for the plasmid-bearing and plasmid-less strains under the three conditions tested, suggesting that the presence of plasmid does not confer selective advantages on the survival of the yeast cells. It is concluded that, even after accidental release of the engineered yeast cells into the environment, elimination rates would be comparable to those for non-recombinant yeast strains.

Molecular cloning and characterization of OB-cadherin, a new member of cadherin family expressed in osteoblasts

The preferential screening of cDNA libraries derived from the mouse osteoblastic cell line MC3T3-E1 has yielded a cDNA clone encoding 796 amino acids including the typical 24-residue-long signal sequence. The predicted amino acid sequence revealed that this protein constitutes a new member of the cadherin family. We propose the name OB-cadherin (OB for osteoblast) for this new protein. RNA analyses revealed that the OB-cadherin gene is selectively expressed in osteoblastic cell lines, precursor cell lines of osteoblasts, and primary osteoblastic cells from calvaria, as well as in lung, testis, and brain tissues at low levels. Transfection of OB-cadherin cDNA into L cells resulted in the acquisition of the Ca(2+)-dependent adhesive property. Two different forms of the human OB-cadherin cDNA were subsequently cloned; one is a counterpart of mouse OB-cadherin gene, and the other encodes a protein with a truncated cytoplasmic domain. The results suggest that the newly found OB-cadherin might have an important role in bone formation.

Cloning and characterization of OSF-3, a new member of the MER5 family, expressed in mouse osteoblastic cells

A cDNA library prepared from the mouse osteoblastic cell line, MC3T3-E1, was screened for the presence of specifically expressed genes by employing subtraction hybridization/differential screening methods. A cDNA clone was identified and sequenced, encoding a protein designated as osteoblast specific factor 3 (OSF-3) comprising 199 amino acids. RNA dot blot analysis indicated weak OSF-3 expression in thymus, spleen, brain, lung, testis, and heart, and high expression in kidney and liver. A homology search of an amino acid sequence database revealed a strong relationship of OSF-3 to the MER5 (gene preferentially expression in murine erythroleukemia cells) protein and human pag (proliferation associated gene) product. This indicates that OSF-3 plays an intrinsic role in the proliferation and/or differentiation of bone cells.

Specific targeting and killing activities of anti-P-glycoprotein monoclonal antibody MRK16 directed against intrinsically multidrug-resistant human colorectal carcinoma cell lines in the nude mouse model

Anti-P-glycoprotein (P-gp) monoclonal antibody, MRK16, and its F(ab')2 fragment were evaluated for its therapeutic efficacy to P-gp-mediated multidrug resistant human colorectal carcinoma cell lines in a nude mouse model. In a blood clearance experiment, 125I-labeled MRK16 had a half-life (16 h) 7 times longer than its F(ab')2 fragment (half-life of 1.8 h) in circulation in nude mice, and approximately 16 and 5% of MRK16 were retained on days 10 and 20 after injection, respectively. In biodistribution experiments using nude mice bearing HCT-15, an intrinsically resistant cell line, 125I-labeled MRK16 accumulated at the tumor site significantly higher than its F(ab')2 fragment as revealed by the percentage of injected dose/g of tissue values (7.4 versus 0.6%) on day 3 after injection. In contrast, the tissue to blood ratio at the tumor site of the MRK16 was significantly lower than that of its F(ab')2 fragment (1.2 versus 10.5). Specific targeting of the MRK16 F(ab')2 fragment to the P-gp-positive tumor (HCT-15) but not to the P-gp-negative tumor (COLO 205) was observed in the nude mice bearing both tumors. In the therapeutic efficacy tests, when administered i.v. 3 times on days 1, 4, and 7 after tumor s.c. inoculation, MRK16 alone showed the significant inhibition of tumor growth of P-gp-positive cell lines, HCT-15, DLD-1, SW480, and SW1417 in contrast to cases of P-gp-negative cell lines, COLO 205 and KM20L2. This inhibitory effect of MRK16 was enhanced in combination with Adriamycin, which alone hardly inhibited the tumor growth. However, MRK16 F(ab')2 fragment alone, even at 1 mg/mouse, had little inhibitory effect on the growth of HCT-15 in the same treatment schedule. When administered at early palpable stage, the degree of HCT-15 tumor growth suppression depended on the number of MRK16 injections. At more progressed stages, treatment with MRK16 alone showed little antitumor activity but when combined with Adriamycin resulted in significant suppression of tumor growth. The present results suggest that MRK16 may be useful for in vivo immunoscintigraphy and immunotherapy of multidrug-resistant colorectal carcinoma.

Antibody recognition of the recombinant human nuclear antigens RNP 70 kD, SS-A, SS-B, Sm-B, and Sm-D by autoimmune sera

Five human nuclear antigens, RNP 70 kD, SS-A, SS-B, Sm-B and Sm-D, were produced in E. coli using the expression vector pSEM. cDNAs encoding these antigens were ligated to a truncated lacZ' gene of the vector and the beta-galactosidase fusion proteins were efficiently expressed as intracellular inclusion bodies after isopropyl-beta-thiogalactopyranoside induction. The antibody reactivities of these fusion proteins were evaluated by Western blot and by ELISA employing panel sera from patients with autoimmune diseases such as systemic lupus erythematosus, Sjögren's syndrome or mixed connective tissue disease. The three fusion proteins, RNP 70 kD, SS-B, and Sm-B, showed good reactivities in both systems, whereas the other two fusion proteins, SS-A and Sm-D, showed poor and no reactivity in both systems, respectively. It can be concluded that RNP 70 kD, SS-B and Sm-B recombinant antigens are useful reagents for the differential diagnosis of the autoimmune diseases.

Osteoblast-specific factor 2: cloning of a putative bone adhesion protein with homology with the insect protein fasciclin I

A cDNA library prepared from the mouse osteoblastic cell line MC3T3-E1 was screened for the presence of specifically expressed genes by employing a combined subtraction hybridization/differential screening approach. A cDNA was identified and sequenced which encodes a protein designated osteoblast-specific factor 2 (OSF-2) comprising 811 amino acids. OSF-2 has a typical signal sequence, followed by a cysteine-rich domain, a fourfold repeated domain and a C-terminal domain. The protein lacks a typical transmembrane region. The fourfold repeated domain of OSF-2 shows homology with the insect protein fasciclin I. RNA analyses revealed that OSF-2 is expressed in bone and to a lesser extent in lung, but not in other tissues. Mouse OSF-2 cDNA was subsequently used as a probe to clone the human counterpart. Mouse and human OSF-2 show a high amino acid sequence conservation except for the signal sequence and two regions in the C-terminal domain in which 'in-frame' insertions or deletions are observed, implying alternative splicing events. On the basis of the amino acid sequence homology with fasciclin I, we suggest that OSF-2 functions as a homophilic adhesion molecule in bone formation.

A simple and rapid method for cryopreservation of mouse 2-cell embryos by vitrification: Beneficial effect of sucrose and raffinose on their cryosurvival rate

Survival of mouse 2-cell embryos was evaluated after exposure to 1.38, 2.75 or 5.5 M single cryoprotectants [dimethylsulphoxide (DMSO), acetamide (Ac) and propylene glycol (PG)], components frequently utilized as a vitrification solution, for 0.5, 1, 2 and 10 minutes at room temperature prior to vitrification. More than 80 % of the treated embryos developed to normal blastocysts in culture, after exposure to 1.38-2.75 M of each reagent for 0.5 minutes, although Ac tended to provide with have a deleterious effect on their survival. When the embryos were vitrified with solutions containing DP (2.75 M DMSO and 2.75 M PG) plus 0, 0.5 and 1.0 M Ac after a 0.5-minute exposure, their in vitro survival rates to the blastocysts were 44, 41 and 37%, respectively, showing no significant difference among them (x(2)=0.1-0.6, P>0.05). This indicates that the presence of Ac is not always needed for vitrifying mouse 2-cell embryos. Embryos, that had been vitrified with DP solution supplemented with 1.0 M sucrose (DPS) after a 0.5- minute exposure, exhibited significantly higher in vitro survival rate (82%) than those vitrified with DP (44%) (x(2)=23.4, P<0.001). Similar high survival rate (81%) was obtained when they were vitrified with DP plus 0.16 M raffinose (DPR) (x(2)=28.3, P<0.001). In vivo survival of embryos vitrified with DPS or DPR after a 0.5-minute exposure was both 49%, and there was no significant difference comparing to the unvitrified control group (60%). This method is rapid, efficient and reliable, and thus may be of practical use for cryopreserving mouse 2-cell embryos.

cDNA expression cloning of the 85-kDa protein overexpressed in adriamycin-resistant cells

An 85-kDa cell surface protein recognized by monoclonal antibody MRK-20 was identified in adriamycin-resistant tumor cells. The expression of the 85-kDa protein has recently been reported to be associated with the differentiation of hematopoietic cells. However, the primary structure of the 85-kDa protein has not been determined. To clarify its primary structure, we carried out cDNA expression cloning of the 85-kDa protein with monoclonal antibody MRK-20. We found that the 85-kDa protein is identical to CD36 (GP VI), but at least two species of transcript exist in the tumor cells and one of these transcripts has a novel sequence at the 3'-region. The transcript with the novel sequence at the 3'-region was found to be expressed during the differentiation of hematopoietic cells.

Gene introduction into mouse blastocysts via "pricking"

It is a well-known phenomenon that cultured mammalian cells that have been pricked in the presence of foreign DNA can be transformed. This micromanipulation 'pricking' technique was applied to mouse blastocysts to determine whether uptake of exogenous DNA would occur in the embryos. The middle region of the inner cell mass (ICM) was pricked three times in each blastocyst in a medium containing a linearized plasmid DNA. When the 60 treated blastocysts were transferred to the uterine horns of pseudopregnant females, 30 developing fetuses (50%) at the mid-gestation stage were obtained. Twenty-two of the 30 fetuses (73%) had less than 1 copy of the foreign DNA per diploid cell, as revealed by polymerase chain reaction (PCR)-Southern analysis, a sensitive technique combined with Southern blot processing of the PCR products. The 8 other fetuses were negative for the foreign DNA. When blastocysts were pricked in the presence of vector DNA coupling E. coli beta-galactosidase (beta-gal) gene to a mouse metallothionein-I (MT-I) promoter and assessed for beta-gal activity histochemically after 1 and 5 days of culture in the presence of 1 microM CdCl2, at least 65% of the embryos exhibited beta-gal activity mainly in the ICM region. These results indicate that mouse blastocysts can be transfected with a relatively high efficiency after pricking, and that the introduced gene expression occurs. This approach provides a means of mapping the regulatory elements of genes that are active in the mouse blastocyst ICM, and may be useful in investigating the fate of the ICM cells in an intact blastocyst by labeling them via pricking technique.

Genomic organization of the mouse OSF-1 gene

The mouse OSF-1 protein (also known as pleiotrophin, HB-GAM, HBGF-8, or HBNF) gene was isolated from a mouse genomic library and sequenced. OSF-1 is a 15-kD secreted protein specifically expressed in bone and brain, and is believed to play a role in brain development and osteogenesis. The mouse OSF-1 gene consists of at least 5 exons and 4 introns and spans > 32 kb. Computer analysis of approximately 4 kb of 5'-flanking sequence of the OSF-1 gene revealed two candidate promoter regions. One candidate promoter contains a thyroid hormone/retinoic acid-responsive element and the other contains two glucocorticoid-responsive elements. DNA sequence analysis of novel OSF-1 cDNA clones indicates that two promoters can be utilized in MC3T3-E1 osteoblastic cells. The overall organization of the mouse OSF-1 gene is similar and the locations of the three exon-intron junctions within the coding region are identical to the mouse gene encoding the differentiation-related factor midkine (MK). Based on this similarity and on the high degree of nucleotide sequence homology (approximately 55%) of mouse OSF-1 and mouse MK, we conclude that OSF-1 and MK are generated from a common ancestral gene and are members of a family of structurally and probably functionally related proteins.

Expression and purification of biologically active human OSF-1 in Escherichia coli

OSF-1 (also known as pleiotrophin, HB-GAM, HBGF-8 or HBNF) is a heparin-binding, neurotrophic protein. Its tissue-specific expression in rats is developmentally regulated and the protein is highly conserved between species. The protein is believed to be involved in neuronal development. Previous experiments in our laboratory showed that OSF-1 is primarily expressed in brain and bone. The biological function of OSF-1 in bone is unknown. In order to overcome the limited availability of the native protein, we now report on the high-level expression of human OSF-1 in Escherichia coli. The protein is present in the form of inclusion bodies, which were isolated and solubilized. The partially purified protein was refolded and further purified employing heparin sepharose chromatography. N-terminal sequence determination revealed the same amino acid sequence as the natural mature protein. The isolated backfolded recombinant human OSF-1 did promote neurites outgrowth in primary cultures of cortical neurons.

Tac promoter vectors incorporating the bacteriophage T7 gene 10 translational enhancer sequence for improved expression of cloned genes in Escherichia coli

Two new plasmid expression vectors, pTacT7 and pTacT7L, have been constructed, which incorporate between the tac promoter and a downstream NcoI-HindIII polylinker sequence a synthetic sequence derived from the region upstream from gene 10 of bacteriophage T7 (g10-L). This sequence was recently shown to act as a translational enhancer (Olins et al., 1988) and was termed "Epsilon" (Enhancer of Protein Synthesis Initiation) element (Olins and Rangwala, 1989). In this communication we describe in detail the construction of ptacT7 and ptacT7L. Furthermore, we present evidence that the "Epsilon" element is able to enhance 3 to 20-fold the expression levels of two poorly expressed test genes encoding the human placental proteins PP9 and PP15. On the other hand, the expression levels of two highly expressed test genes encoding the human placental proteins PP4 and FXIIIa could not be further enhanced by the presence of the "Epsilon" element. These experiments show that the T7 gene 10 leader sequence can be utilized to improve the expression yields of otherwise poorly expressed heterologous genes in Escherichia coli.

Surface expression of malarial antigens in Salmonella typhimurium: induction of serum antibody response upon oral vaccination of mice

The Escherichia coli OmpA protein can serve as a carrier for the expression of foreign antigens on the surface of gram-negative bacteria. Employing OmpA vectors, immunogenic moieties of the Plasmodium falciparum blood stage antigens SERP and HRPII have been expressed in the attenuated Salmonella typhimurium SR-11 strain. Upon induction, the malaria specific sequences of 189 (HRPII) and 451 (SERP) amino acids, fused into the OmpA protein, have been expressed. By indirect immunofluorescence studies, live bacteria expressing the fusion proteins react anti-SERP and anti-HRPII sera, respectively, indicating that the hybrid OmpA proteins become integrated into the bacterial outer membrane and expose the malarial antigens at the exterior surface. Mice that were immunized orally with S. typhimurium cells expressing HRPII and SERP on their surface show a humoral immune response as determined by the anti-SERP and anti-HRPII IgG and IgM titres. From these experiments it can be concluded that the OmpA surface expression system in combination with established Salmonella vaccine strains can be used to efficiently deliver large antigens to the mucosal immune system.

Expression of the human blood coagulation protein Factor XIIIa in Saccharomyces cerevisiae: dependence of the expression levels from host-vector systems and medium conditions

The human blood coagulation protein Factor XIIIa (FXIIIa) was expressed in Saccharomyces cerevisiae employing Escherichia coli-yeast shuttle vectors based on a 2-mu plasmid. Several factors affecting high production yield of recombinant FXIIIa were analysed. The use of the regulatable GAL-CYC1 hybrid promoter resulted in higher FXIIIa expression when compared with the constitutive ADCI promoter. Screening for suitable yeast strains for expression of FXIIIa under the transcriptional control of the GAL-CYC1 hybrid promoter revealed a broad spectrum of productivity. No obvious correlation between the expression rate and the genetic markers of the strains could be identified. The medium composition markedly influenced the FXIIIa expression rates. The expression of FXIIIa was strictly regulated by the carbon source. Glucose as the only sugar and energy source repressed the synthesis of FXIIIa, whereas addition of galactose induced FXIIIa expression. Special feeding schemes resulted in a productivity of up to 100 mg FXIIIa/l in shake flasks.

Annexin proteins PP4 and PP4-X. Comparative characterization of biological activities of placental and recombinant proteins

The human placental proteins PP4 and PP4-X, belonging to the annexin protein family, were expressed in Escherichia coli at high yield. The proteins were purified to homogeneity. The physicochemical parameters of the recombinant proteins were determined and compared with those of their natural placental counterparts. Except for a minor change in the pI, the proteins appeared to be indistinguishable by several criteria. Both recombinant PP4 and recombinant PP4-X were biologically active in a thromboplastin inhibition test and in a phospholipase A2 inhibition test.

Escherichia coli-derived envelope protein gD but not gC antigens of herpes simplex virus protect mice against a lethal challenge with HSV-1 and HSV-2

Immunization studies with HSV-1 and HSV-2 envelope proteins expressed in Escherichia coli were performed. After active immunization of mice with a gD-1 antigen (Leu53-Ala312) expressed as a fusion protein, the animals were protected from a lethal challenge with HSV-1 and HSV-2. In addition, antisera from rabbits immunized with the same gD-1 antigen also conferred passive immunity to mice against a challenge infection with either HSV-1 or HSV-2. In contrast to these successful gD-1 protection experiments, various gC-1 and gC-2 fusion proteins from E. coli failed to induce protective immunity. Moreover, the mice sera from immunized animals were not able to react with the authentic, glycosylated gC-1 and gC-2 envelope proteins, whereas sera raised against authentic gC-1 and gC-2 glycoproteins do recognize the gC fusion proteins from E. coli. These results indicate, that E. coli might represent an ideal system for expressing gD antigens as a possible component of a HSV vaccine, whereas gC antigen cannot be produced in an immunocompetent form in E. coli.

Cloning and expression of a cDNA encoding human placental protein 11, a putative serine protease with diagnostic significance as a tumor marker

The placental protein 11 (PP11) can act as a tumor marker because of its specific association with various forms of cancer. A lambda gt11 cDNA library prepared from human placenta was screened with a polyclonal anti-PP11 antiserum. Out of 10(6) independent clones, only one clone reacted with the anti-PP11 antiserum. The isolated cDNA coded only for the carboxy-terminal part of PP11 and was subsequently used to rescreen a lambda gt10 placental cDNA library. Two cDNA clones out of 10(6) screened were identified encoding the entire protein of 369 amino acids, including a typical hydrophobic signal sequence of 18 amino acids. Expression of the PP11 cDNA coding sequence in Escherichia coli resulted in the synthesis of a protein with the expected size which can be specifically immunoprecipitated with anti-PP11 antiserum. Fractionation experiments revealed that two forms of the protein are present in the bacterial cell: a higher-molecular-weight form of approximately 42 kD in the cytoplasm and a smaller-molecular-weight form of approximately 42 kD in the periplasm. This result indicates that PP11 can be synthesized in E. coli and is process by removal of the hydrophobic signal sequence. Both the placental and the processed recombinant PP11 protein exhibit a protease activity.

Cloning and prokaryotic expression of a biologically active human placental aldose reductase

cDNA clones coding for human aldose reductase (AR) were isolated by antibody screening of a placental lambda gt11 cDNA library. The cDNA comprises the entire coding region and has a total length of 1,394 bp. The sequence deduced from the open reading frame encodes a protein of 316 amino acids and its amino acid composition is identical to the placental protein 9 (PP9), whose isolation and characterization were described by Bohn et al. (1982). The amino acid sequence of the placental human AR shows high homology to the rat AR; both proteins belong to the same protein superfamily as human liver AR, frog lens rho-crystallin, and bovine lung prostaglandin F synthase. Northern blot hybridization analysis revealed a size for the AR mRNA of approximately 1,500 bases. In addition to the full-length cDNA, one lambda gt11 clone was isolated which carries a putative intron of 597 bp at nucleotide position 754, corresponding to amino acid position 247. Expression of the AR cDNA in Escherichia coli resulted in the synthesis of a protein with a molecular weight of approximately 35 kD which can be immunoprecipitated specifically with antiserum raised against PP9. Despite the absence of a typical signal sequence, the human aldose reductase is partially translocated into the periplasm of the E. coli cells, where it is present in an enzymatically active form.

Tightly regulated tac promoter vectors useful for the expression of unfused and fused proteins in Escherichia coli

A series of new plasmid expression vectors (the pTrc series) has been constructed for the regulated expression of genes in Escherichia coli. Based on pKK233-2 [Amann and Brosius, Gene 40 (1985) 183-190], the vectors carry a strong hybrid trp/lac promoter, the lacZ ribosome-binding site (RBS), the multiple cloning site of pUC18 and the rrnB transcription terminators. With the aid of synthetic oligodeoxynucleotides, the multiple cloning site has been inserted behind an NcoI site in three reading frames. Thus, the vectors are equally useful for the expression of proteins in their authentic, non-fused form (by using the NcoI site) and for the expression of fusion proteins (by choosing any of the cloning sites in the correct translational frame). To ensure complete repression of the hybrid trp/lac promoter during construction and growth in any host strain, the lacIq allele of the lac repressor gene was added to some of the vectors. The complete vector nucleotide sequence and examples of heterologous gene expression (human coagulation factor XIIIa and human placental anticoagulant protein PP4) with the new vectors are presented.

Synthesis of human factor XIIIa in bacterial cells

The coding sequence for human factor XIIIa (FXIIIa) was introduced into Escherichia coli expression vectors. Bacterial cells transformed with the recombinant plasmids synthesized fusion proteins of the expected molecular weights and the proteins were shown to be immunoreactive with anti-FXIII antibodies. Furthermore, with the help of oligodeoxynucleotide synthesis, we constructed a plasmid which directs the synthesis of the human FXIIIa protein in the unfused form. Sequence determination at the aminoterminus of this protein revealed the identical sequence compared to placental FXIIIa. The protein is expressed intracellularly in a denatured and biologically inactive form. It constitutes approximately 2% of total cellular protein and can easily be purified by standard methods.

Isolation and expression of cDNA coding for a new member of the phospholipase A2 inhibitor family

The placental protein PP41,2 was shown to have thromboplastin-inhibitor activity. We used partial amino acid sequence information from PP4 cyanogen bromide fragments to design oligonucleotide probes for the screening of a human placental cDNA library. In addition to the PP4 cDNA we isolated a cDNA coding for a protein with considerable homology which we subsequently termed PP4-X. PP4 and PP4-X belong to the phospholipase A2 inhibitor family, as judged by their homology to lipocortin I and calpactin I3. The full-length PP4-X cDNA encodes a protein of 321 amino acid residues including a fourfold repeat structure. Northern blot analysis using the PP4-X cDNA reveals two hybridizing RNA species of approximately 1400 nucleotides and 2500 nucleotides, respectively. The shorter one could well represent the PP4-X transcript which is in good agreement with the isolated cDNA insert of 1326 nucleotides. Expression of the PP4-X coding sequence in E. coli resulted in the appearance of a protein which crossreacts with antibodies raised against PP4.

Synthesis of biologically active deletion mutants of human factor VIII:C

The recent cloning and sequence analysis of human factor VIII:C (antihaemophilic factor) revealed a domain structure for the protein which can be presented as A1-A2-B-A3-C1-C2. In this report we describe the construction of two altered factor VIII:C cDNAs coding for molecules in which a part (amino acids 816 to 1598) or all of the B domain (amino acids 741 to 1689) was removed. In the latter mutant a new thrombin cleavage site has been created, which does not exist in wild-type factor VIII:C. The mutated cDNAs were cloned into eucaryotic expression vectors based on regulatory sequences of the virus SV40 and transfected into two different mammalian cell lines. Both truncated recombinant factor VIII:C molecules were secreted into the culture medium, showed full biological activity and could be activated by thrombin.

Characterization of cDNA coding for human factor XIIIa

A cDNA library prepared from human placenta has been screened for sequences coding for factor XIIIa, the enzymatically active subunit of the factor XIII complex that stabilizes blood clots through crosslinking of fibrin molecules. Two oligonucleotides, based on the amino acid sequences of tryptic peptides of factor XIIIa, were used as hybridization probes. Of 0.36 X 10(6) independent recombinants, 1 clone was identified that hybridized to both probes. The insert of 1704 base pairs coded for the amino-terminal 541 amino acid residues of the mature factor XIIIa molecule. Blot-hybridization analysis using this cDNA as a probe showed that the factor XIIIa mRNA from placenta has a size of approximately 4000 bases. The insert was used to rescreen cDNA libraries and to identify further factor XIIIa-specific sequences. The total length of the isolated factor XIIIa cDNA is 3905 bases, and it codes for a protein of 732 amino acids. In spite of the presence of factor XIII in blood plasma, we could not identify a leader sequence typical for secreted proteins.

"ATG vectors' for regulated high-level expression of cloned genes in Escherichia coli

A plasmid cloning vector system has been constructed that allows for the production of large quantities of foreign proteins or fragments thereof, in an unfused state. These vectors provide strong regulated trp-lac fusion promoters and the lacZ ribosome-binding site (RBS) followed by an ATG translation initiation codon at an appropriate distance from the RBS. The ATG codon is located within a unique NcoI restriction site (CCATGG). Digestion with NcoI exposes the ATG for fusion. Gene fragments lacking a prokaryotic RBS and/or ATG start codons can be inserted in several ways. Expression experiments using a truncated cI gene of bacteriophage lambda or a large portion of the coding region of the Herpes simplex virus type 1 glycoprotein D gene have been performed. The results of these studies show that the vectors are useful for the high-level expression of prokaryotic and eukaryotic genes in Escherichia coli.

Expression of Herpes simplex virus type 1 glycoprotein C antigens in Escherichia coli

DNA fragments encoding structural information of the Herpes simplex virus type 1 (HSV-1) glycoprotein C (gC) gene were cloned into pUC plasmids [Vieira and Messing, Gene 19 (1982) 259-268]. None of the hybrid plasmids were able to direct the synthesis of significant amounts of gC related peptides. Several of the plasmid-bearing strains, however, exhibited inhibition characteristics which can be correlated with the presence on the plasmid of specific gC gene sequences. After insertion of gC DNA fragments into expression vector pMF2 between phage lambda repressor gene cI and lacZ, significant amounts of cI::gC::beta-galactosidase fusion proteins are synthesized. These tripartite fusion proteins are immunologically reactive with anti-HSV-1 antisera. The expression system based on pMF2 can be generally used to identify and express foreign antigens in Escherichia coli.

Ventricular arrhythmias before and late after aortic valve replacement

The influence of aortic valve replacement on the incidence of ventricular arrhythmias was studied by 24-hour Holter electrocardiographic monitoring in 45 patients immediately before and 14 +/- 7 months after operation. Ventricular arrhythmias were graded according to the Lown criteria. Preoperative left ventricular (LV) ejection fraction (EF) was determined by angiography and postoperative LVEF by gated blood pool scintigraphy. Repetitive ventricular arrhythmias (Lown grade 4A/B) were associated with a reduced LVEF (less than 55%) before and after operation. In 24 patients with preoperative normal LVEF (greater than or equal to 55%) (group A), mean LVEF remained unchanged after operation (72% vs 71%). Pre- and postoperative ventricular premature complex (VPC) frequency (45 +/- 99 vs 39 +/- 94 VPC/24 hours) and grade (1.3 vs 1.4) were not significantly different. However, in 17 patients with preoperative impaired LVEF (less than 55%) (group B, LVEF preoperatively 40 +/- 8%) and marked postoperative improvement (greater than 10%) (LVEF postoperatively 64 +/- 7%), mean VPC frequency decreased from 536 to 69 VPCs/24 hours and mean VPC grade was reduced from 3.8 to 1.5. Complex VPCs were found preoperatively in all 17 patients of group B, but in only 5 patients after operation. Four patients had a reduced LVEF preoperatively and it did not improve postoperatively (group C). Postoperative Holter monitoring detected ventricular tachycardia in all 4 patients. This study indicates that repetitive VPCs are infrequent in patients with normal LVEF before and late after aortic valve replacement. In patients with impaired LVEF and complex VPCs preoperatively, the postoperative improvement of LV function is usually accompanied by a reduction of frequent and complex VPCs.

Activity of the hybrid trp-lac (tac) promoter of Escherichia coli in Pseudomonas putida. Construction of broad-host-range, controlled-expression vectors

A broad-host-range vector, pKT240, containing the structural gene (aph) for aminoglycoside phosphotransferase (APH), without promoter, has been constructed. Insertion of DNA fragments carrying promoters upstream of aph gene into the unique EcoRI site of this vector results in the expression of the aph gene and consequently the resistance of the host cells to streptomycin. The new vector has been used to show that the hybrid trp-lac (tac) promoter and the promoter of the lacIQ gene of Escherichia coli are active in Pseudomonas putida. Derivatives of pKT240 containing tac and lacIQ sequences may be used as wide-host-range expression vectors. Regulated overproduction of APH and catechol 2,3-oxygenase can be obtained with the aid of the new vectors in both E. coli and P. putida.

Vectors bearing a hybrid trp-lac promoter useful for regulated expression of cloned genes in Escherichia coli

A strong promoter has been cloned on a series of plasmid vectors that facilitate the expression of cloned genes. This promoter, named tac [first described by DeBoer et al. (in Rodriguez, R.L. and Chamberlin, M.J. (Eds.),Promoters, Structure and Function. Praeger, New York, 1982, pp. pp. 462-481)] contains the -10 region of the lacUV5 promoter and the -35 region of the trp promoter. Our vectors contain various cloning sites followed by transcription termination signals. In addition, we describe plasmids that facilitate the conversion of the lac promoter to the stronger tac promoter. Thus, preexisting gene fusions using the lac or the lacUV5 promoter can be readily converted to tac promoter gene fusions without changing the ribosome-binding site (RBS). The tac promoter is repressed in lacIQ strains and can be induced by isopropylthio-beta-D-galactoside (IPTG). Studies of expression of the cI repressor of bacteriophage lambda show that the tac promoter is at least five times more efficient than the lacUV5 promoter. Under optimal conditions lambda repressor constitutes up to 30% of the total cellular protein.

Purification of biologically active simian virus 40 small tumor antigen

The simian virus 40 small tumor antigen (t antigen) gene has been cloned downstream from a hybrid Escherichia coli trp-lac promoter and a suitable ribosome binding site. A bacterial clone (865i) transformed by such a plasmid (pTR865) expresses this gene and, under optimal conditions, can produce greater than or equal to 5% of its total protein as t antigen. Soluble extracts of such a clone were relatively depleted in t antigen, which was found in the initial pellet fraction. The protein was recovered from this fraction in a significantly purified form by extraction with urea-containing buffer. After gel filtration of such t antigen-enriched solutions, highly purified protein was obtained. When either this fraction (freed of urea) or NaDodSO4 gel-purified 865i t antigen (rendered free of detergent) was injected into untransformed rat cells, dissolution of intracellular actin cable networks was observed.

Lack of interaction between the tetracyclic antidepressant maprotiline and the centrally acting antihypertensive drug clonidine

The well known interaction between tricyclic antidepressants and the centrally acting antihypertensive drug clonidine, namely impairment of the antihypertensive effect of clonidine, is thought to be related to blockade of noradrenaline uptake or competition at central alpha-receptors. The tetracyclic antidepressant maprotiline has been shown to be a potent inhibitor of noradrenaline uptake and it might, therefore, interfere with the antihypertensive action of clonidine. The possible interaction of clonidine and maprotiline was studied in 8 healthy subjects using doses in the therapeutic range. The study followed a double-blind, cross over design, in which clonidine alone (0.3 mg p.o.), clonidine (0.3 mg p.o.) plus maprotiline (100 mg in 4 divided doses over 22 h), maprotiline alone (100 mg in 4 divided doses over 22 h) and placebo were given by the double-dummy technique. Several pharmacodynamic parameters were measured for 12 h after administration of the drugs (supine and erect blood pressure, heart rate, saliva production and sedation). Concurrent administration of maprotiline did not alter the effect of clonidine and neither the size nor the time of the maximal response after clonidine were influenced by maprotiline. It is concluded that [1] blockade of noradrenaline uptake is not associated with the interaction of tricyclic antidepressants and clonidine, and [2] maprotiline should be preferred to tricyclic antidepressants in hypertensive patients on clonidine therapy if a concomitant depressive illness has to be treated.

Unusual behaviour of SPO1 DNA with respect to restriction and modification enzymes recognizing the sequence 5'-G-G-C-C

SPO1 DNA contains only 5 cleavage sites for restriction enzymes which recognize and cleave the sequence 5'-G-G-C-C (HaeIII or BsuR). Fragments of SPO1 DNA cloned in E. coli to substitute 5'-hydroxymethyluracil (HMU) by thymine (T) remain resistant to HaeIII indicating that this unexpectedly small number of cleavages by HaeIII is not correlated with the presence of HMU in the normal phage DNA. It was previously shown that SPO1 is neither subject to B. subtilis R restriction (Trautner et al., 1974) nor modification in vivo (Günthert et al., 1975). We now show that SPO1 DNA can however be restricted and modified in vitro.

Bacteriophage SPP1 polypeptides synthesized in infected minicells and in vitro

Minicells produced by B. subtilis CU403divIVB1 and infected by SPP1 synthesize at least 46 polypeptides which can be separated by polyacrylamide gel electrophoresis. These polypeptides represent the expression of 86% of the SPP1 genome's coding capacity. Infection of minicells by sus mutants and deletion mutants of SPP1 has permitted a correlation of genetic location with gene product and has shown that SPP1 normally synthesizes at least 8 non-essential polypeptides. Restriction fragments of SPP1 produced by EcoRI digestion of SPP1 DNA have been purified and used as template DNA in a coupled transcription/translation system derived from E. coli to determine the polypeptides encoded by the individual fragments. SPP1 expression in minicells differs from SPP1 expression in nucleated cells (Esche, 1975) in that late syntheses are not dependent on phage DNA replication in infected minicells.

DNA synthesis in toluene-treated bacteriophage-infected minicells or Bacillus subtilis

Bateriophage (phi29, SPP1, or SPO1)-infected, toluene-treated minicells of Bacillus subtilis are capable of limited amounts of non-replicative DNA synthesis as measured by incorporation of [3H]dTTP into a trichloroacetic acid-precipitable form. The [3H]dTTP is covalently incorporated into small DNA fragments which result from the degradation of a small percentage of the infecting phage genomes (molecular weights in the range of 2 . 10(5)). Short exposure of the DNA molecules containing the incorporated [3H]dTMP to Escherichia coli exonuclease III results in over 90% of the E13H]dTMP being converted to a trichloroacetic acid-soluble form. The synthesis is totally dependent on host-cell enzymes and is not inhibited by the addition of chloramphenicol, rifampicin, nalidixic acid and mitomycin C and only slightly (approx. 20%) inhibited by the addition of 6-(p-hydroxyphenylazo)-uracil.