Aims: To establish whether germination of Botrytis cinerea was affected by the symbiosis of Bacillus subtilis L-form bacteria with Chinese cabbage.Methods and Results: Germinating seeds of Chinese cabbage were co-cultivated with either L-forms of Bacillus subtilis or 59,6 (w/v) mannitol by soaking for 3 h. Seeds were then washed in sterile water, sown on a minimal medium and incubated in controlled conditions. L-form symbiosis was detected over a time course by ELISA. Conidial germination of Botrytis cinerea was significantly reduced on cotyledonous leaves of L-form-treated plants compared with controls.Conclusions: Symbiosis of B. subtilis L-form bacteria during seed germination of Chinese cabbage inhibits conidial germination in plants on subsequent exposure to Botrylis cinerea.Significance and Impact of the Study: This is the first account of plant symbiosis with L-form, bacteria showing antagonism to a fungal plant pathogen. This has promising implications for the use of this L-form as a biocontrol agent.

Aims: To develop an ELISA for the detection of antigens derived from stable Bacillus subtilis L-form bacteria and to detect these in plants injected with L-form bacteria.Methods and Results: A sandwich ELISA was developed and its specificity was investigated using L-forms and cell-walled forms of B. subtilis, different Bacillus species and a range of bacteria isolated from glasshouse-grown strawberry plants. The detection limits of the ELISA were approximately 10(3) viable cells ml(-1) for L-forms compared with 10(7) viable cells ml(-1) for cell-walled forms. Results showed that L-forms survived and moved within strawberry tissues injected with L-form bacteria.Conclusion: An ELISA that selectively detects B. subtilis L-form bacteria was developed and shown to confirm the presence of L-forms in plants.Significance and Impact of the Study: This will be a valuable rapid method to further studies on L-form plant interactions.

Leukaemic and normal bone marrow samples were compared in terms of their content of the fibrinolytic agents, tissue plasminogen activator (t‐PA) and urokinase‐type plasminogen activator (u‐PA) and their inhibitors, plasminogen activator inhibitors 1 and 2 (PAI‐1 and PAI‐2). Normal marrow contained t‐PA as the principal plasminogen activator, whereas in leukaemic marrow samples u‐PA was the predominant activator. Both normal and leukaemic marrows contained PAI‐1 in similar amounts, but whereas normal marrow contained significant amounts of PAI‐2 the leukaemic marrows contained very little. Plasminogen activators were present in uncomplexed, active forms and plasmin–α2‐antiplasmin complexes were generated locally more prominently in leukaemic marrows. u‐PA associated with blast cells may contribute to the severe forms of haemorrhage sometimes occurring in myeloid types of leukaemia.

Department of Molecular & Cell Biology, University of Aberdeen, Institute of Medical Sciences, Aberdeen AB25 2ZD, Scotland, UK

Departments of Medicine & Therapeutics and of Molecular & Cell Biology, University of Aberdeen and Department of Anaesthetics, Aberdeen Royal Hospitals NHS Trust, Aberdeen, Scotland, UK

Department of Molecular and Cell Biology, University of Aberdeen, Marischal College, Aberdeen AB9 1AS, UK

Departments of Molecular and Cell Biology, and Medicine and Therapeutics, University of Aberdeen, Scotland, UK

Department of Molecular and Cell Biology, University of Aberdeen, Marischal College, Aberdeen AB9 1AS, UK

Septic patients with normal white cell responses had high plasma levels of the principal inhibitor of fibrinolysis, plasminogen activator inhibitor 1 (PAI-1). Severely leucopenic septic patients demonstrated less marked changes in plasma PAI-1. Polymorphs (PMN) from septic patients contained higher levels of PAI-1 than corresponding cells from non-septic subjects. Thus leucocytes may enhance the fibrinolytic inhibition characteristic of sepsis. If shock complicated sepsis, however, plasma PAI-1 levels were grossly elevated in the presence or absence of leucopenia, thus indicating a source for PAI-1 other than leucocytes. Endothelial cells (EC) secrete PAI-1 in culture. Go-culture of EC with mononuclear cells (MC) from normal subjects significantly enhanced PAI-1 release into culture media. This phenomenon was, however, significantly reduced by MC from septic patients.

Three regions in PAI-1 were selected for epitope analysis on the basis of their proposed significance for the functional activity of PAI-1 and their surface-location. Antisera were raised against 3 peptides synthesized for the regions 111P-V121 125D-N137 and 335A-E350 in PAI-1 and were evaluated by dot immunobinding assay. Confirmation of the antigenicity of the peptides was followed by synthesis of solid-phase sequential overlapping octapeptides for each region. Binding of the octapeptides to antisera against the 3 peptides and to a panel of monoclonal antibodies against PAI-1 was evaluated by ELISA.

Tumour cells possess the cell surface protease guanidinobenzoatase (GB) which can be located by the fluorescent probe 9-amino acridine (9-AA). Frozen sections and formaldehyde fixed sections of tumour tissue were used to demonstrate the interactions between GB, 9-AA and two protein inhibitors of GB. A cytoplasmic extract from the tumour tissue, and a purified inhibitor of plasminogen activator (PAI-1) were shown to be exchangeable components of the enzyme-inhibitor complex on the fixed tumour cell surfaces. The evidence suggests that GB is functionally very similar to plasminogen activator and that this enzyme can be regulated by protein inhibitors in vivo and also by changes in the redox potential at the cell surface.