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

cones In geometry, a cone is a three-dimensional figure that tapers smoothly from a flat base (typically a circle) to a point not contained in the base, called the ''apex'' or '' vertex''. A cone is formed by a set of line segments, half-lines, ...

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

s. It is named after the cycad genus ''

Zamia ''Zamia'' is a genus of cycad of the family Zamiaceae, native to North America from the United States (in Georgia and Florida) throughout the West Indies, Central America, and South America as far south as Bolivia. The genus is considered to be ...

''.

Etiology

The disease 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 that extends from the medulla oblongata in the lower brainstem to the lumbar region of the vertebral column (backbone) of vertebrate animals. The center of the spinal c ...

. It is caused by the

toxin A toxin is a naturally occurring poison produced by metabolic activities of living cells or organisms. They occur especially as proteins, often conjugated. The term was first used by organic chemist Ludwig Brieger (1849–1919), derived ...

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 hydrol ...

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 In biochemistry, glycoside hydrolases (also called glycosidases or glycosyl hydrolases) are a class of enzymes which catalyze the hydrolysis of glycosidic bonds in complex sugars. They are extremely common enzymes, with roles in nature inclu ...

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 state government of Queensland, Australia, a Parliament, parliamentary constitutional monarchy. Government is formed by the party or coalition that has gained a majority in the Queensland Legislative Assembly, ...

investigation during the 1890s.

References

Bovine diseases Cycads {{Veterinary-med-stub

Etiology

See also

References