Background It has been reported that some marine cyanophage are temperate and can be induced from a lysogenic phase to a lytic phase by different agents such as heavy metals. However, to date no significant reports have focused on the temperate nature of freshwater cyanophage/cyanobacteria. Previous experiments with cyanophage AS-1 and cyanobacteria Anacystis nidulans have provided some evidence that AS-1 may have a lysogenic life cycle in addition to the characterized lytic cycle. Results In this study, the possible temperate A. nidulans was treated with different concentrations of heavy metal-copper. CuSO 4 with concentrations of 3.1 × 10 -3 M, 3.1 × 10 -4 M, 3.1 × 10 -5 M and 3.1 × 10 -6 M were used to detect the induction of AS-1 from A. nidulans . The population of the host, unicellular cyanobacteria Anacystis nidulans , was monitored by direct count and turbidity while the amount of virus produced was derived from plaque forming units (PFU) by a direct plating method. The ratio of AS-1 release from A. nidulans was also determined. From these results it appears that AS-1 lysogenic phage can be induced by copper at concentrations from 3.1 × 10 -6 M to 3.1 × 10 -4 M. Maximal phage induction occurred at 6 hours after addition of copper, with an optimal concentration of 3.1 × 10 -6 M. Conclusion Cu 2+ is a significant inducer for lysogenic cyanobacterial cells and consequently would be a potential control agent in the cyanobacteria population in fresh water ecosystems.

Cyanobacteria and the cyanophage that infect these bacteria are abundant throughout fresh water and marine ecosystems. Unfortunately, the knowledge of genomic interaction between these cyanophages and their hosts are limited due to the lack of integration of the cyanogroup information. To remedy this deficiency, a Cyanogroup Genomics Knowledge Base (CGKB) for cyanophages and cyanobacteria has been initiated: http://www.cyanogroup.com/. This knowledge base includes: (1) the literature database of freshwater and marine cyanogroups; (2) the genomic database of these cyanogroups including NCBI GenBank data and sequence data from both our laboratory and that of other researchers; (3) data analysis - DNA, protein sequences and phylogenetic analysis; (4) relevant links for the cyanogroups. Regular updates of the local database will be performed to maintain the high accuracy of the analysis and BLAST searches. CGKB also provides sequence and phylogenetic analysis tools for users to search and query any related information stored in the database.

Anacystis nidulans is a simple, unicellular, prokaryotic microorganism. Like other cyanobacteria it is an obligate photoautotroph that is similar to gramnegative bacteria in cell wall structure, replication, and ability to harbor plasmids. Cyanobacteria are excellent organisms to serve as models for the investigation of a wide variety of biological problems, including indicators of environmental pollution. There have been several studies on the effects of heavy metals on A. nidulans (Lee et al. 1991, 1992, 1993, 1994, Singh and Yadava 1985, Whitton and Fahni 1982).

Bordetella pertussis is composed of a series of active components: (1) a heat-labile or dermonecrotic toxin (HLT); (2) a lipopolysaccharide endotoxin (LPS); (3) pertussis toxin; (4) filamentous hemagglutinin (FHA); (5) agglutinogens; (6) outer membrane proteins; (7) adenylate cyclase; and (8) tracheal cytotoxin. Pertussis toxin (PT), also called lymphocytosis-promoting factor (LPF), encompasses a series of biological activities including: (1) histamine-sensitization (HSF); (2) leukocytosis-promoting activity (LPF); (3) LPF-hemagglutinin (LPF-HA); and (4) pancreatic islet-activating protein (IAP). The heat-labile toxin is inactivated during vaccine production. Pertussis toxin is inactivated when heated to 80 degrees C for 30 min and endotoxin at a temperature greater than 120 degrees C for 30 min. The effect of pre- and post-heat treatment on DTP vaccine, Bordetella pertussis endotoxin, pertussis toxin and a pertussis toxin/endotoxin combination, was determined as related to: (1) paw swelling response; (2) LAL activity (endotoxin); and (3) HSF activity. With the exception of DTP and B. pertussis endotoxin, the average paw swelling response after injection of non-treated and heat-treated test samples was similar to the saline control at all measured time intervals. Contrary to anticipated results, heat treatment enhanced the paw-swelling response of DTP vaccine and B. pertussis endotoxin. Endotoxin levels, as measured by LAL, were significantly lower after heat-treatment, with the exception of B. pertussis endotoxin and the E-1 control. The addition of pertussis toxin, B. pertussis endotoxin or pertussis toxin/endotoxin did not restore LAL values to the levels seen for non-treated DTP vaccine.(ABSTRACT TRUNCATED AT 250 WORDS)