Cyanobacteria are well known for their production of a multitude of highly toxic substances. the genus nostoc sp. is regarded as good candidates for producing biologically active secondary metabolites, which are highly toxic to humans and other animals. discovery of several dead dogs, mice, ducks and fish around fresh water of golestan province, prompted us to study the toxic compounds in a strain of nostoc. the aim of this paper is to describe the role of horizontal gene transfer in the evolutionary history of toxic natural products
in this study, nostoc sp. was assessed in phylogenetic and evolutionary perspectives. the structural gene 16s ribosomal rna (rrna), functional genes nif d, psba, nif h, rpoc1, pc-igs, rbcl and toxic genes mcy g, d, e, nos e, nos f were selected as molecular chronometers in this study.
we hypothesized that horizontal gene transfer may play a role in the distribution of toxic biosynthetic genes within the genus nostoc sp.
these results suggest that toxic bioactive compounds induced liver damage and may have significantly contributed to the death of the dog. this case is thus the first reported incident of potential microcystin intoxication in a dog in iran.