Zamia staggers is a fatal nervous disease affecting cattle in areas where they browse on the leaves or fruit of

cycad Cycads are seed plants that typically have a stout and woody (ligneous) trunk with a crown of large, hard, stiff, evergreen and (usually) pinnate leaves. The species are dioecious, that is, individual plants of a species are either male o ...

s—in particular, those of the genus Zamia (thus the name). It is characterised by irreversible paralysis of the hind legs because of the degeneration of the

spinal cord The spinal cord is a long, thin, tubular structure made up of nervous tissue, which extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column (backbone). The backbone encloses the central canal of the sp ...

. It is caused by the

toxin A toxin is a naturally occurring organic poison produced by metabolic activities of living cells or organisms. Toxins occur especially as a protein or conjugated protein. The term toxin was first used by organic chemist Ludwig Brieger (1849 ...

cycasin Cycasin is a carcinogenic and neurotoxic glucoside found in cycads such as ''Cycas revoluta'' and '' Zamia pumila''. Symptoms of poisoning include vomiting, diarrhea, weakness, seizures, and hepatotoxicity. In metabolic conditions, cycasin is hydro ...

and macrozamin, β-glycosides (the sugars of which are glucose and primeverose, respectively) of

methylazoxymethanol Methylazoxymethanol, MAM, is a carcinogen which reduces DNA synthesis. Its derivatives include methylazoxymethanol acetate and cycasin, which they are found in cycad Cycads are seed plants that typically have a stout and woody (ligneous) ...

(MAM), and which are found in all cycad genera. Following ingestion the sugar is removed by bacterial

glycosidase Glycoside hydrolases (also called glycosidases or glycosyl hydrolases) catalyze the hydrolysis of glycosidic bonds in complex sugars. They are extremely common enzymes with roles in nature including degradation of biomass such as cellulose (c ...

in the gut, with the MAM being absorbed. The metabolized toxin produces tumours of the liver, kidney, intestine and brain after a latent period which may be a year or longer. The disease has been known in Australia since the 1860s and was the subject of a

Queensland Government The Queensland Government is the democratic administrative authority of the Australian state of Queensland. The Government of Queensland, a parliamentary constitutional monarchy was formed in 1859 as prescribed in its Constitution, as amended f ...

investigation during the 1890s.

References

External links

The Cycad Pages: Cycad toxicity
Bovine diseases Cycads {{Veterinary-med-stub

See also

References

External links