Cycads

Cyasin, a component of the nut of the cycad tree, a native of tropical environs, produces an acute toxicity in addition to drastically increasing the incidence of Lou Gerhig s disease (amyotropic lateral sclerosis). Cyasin is carcinogenic (102). 

Triaasic Atlantic Ocean begins Conifers, cycads. primitive mammals... 

Ferns and allies b) Seed plants Gymnosperms Conifers, cycads, ginkgos, gnetae 700... 

Cyanuric chloride method, for covalent ligand immobilization, 6 396t Cycads, in nitrogen fixation, 2 7 300 Cyclamate, 22 42 24 234, 236 sweeteners, 2 513-514 Cyclamen aldehyde, aroma chemical derived from toluene, 3 234 Cyclams, 24 41—42... 

Cycads pollination by insects may be one of the earliest forms of insect-pollination. Like conifers, cycads bear their reproductive cells in cones rather than flowers. Individual cycad plants are either male or female, male plants having pollen cones and female plants, seed cones. Fertilization requires transfer of pollen grains from pollen cones to seed cones. The role of insects in this process has received attention in a cycad commonly known as the cardboard palm (Zamia furfuracea). This is a handsome horticultural plant with... 

The specificity of each orchid s scent for only a few kinds of bees is at first surprising. The entire group of orchids makes use of about sixty different fragrance chemicals, each orchid typically using about seven to ten components for its particular scent. Most of these compounds are among the widely distributed plant chemicals we have previously met in cycads and in other flowering... 

In males and females of the weevil Rhopalotria mollis the sequestration of cycasin 235 known from the Mexican cycad Zamia furfuracea was reported [421]. 

Some plants regularly eaten by humans contain neurotoxins that pose serious health problems. On Guam, for example, the seeds of Cycas circinalis used to be an important source of carbohydrates. Seeds of Cycas rumphii were ground into flour for tortillas. However, the seeds contain jS-N-methylamino-i-alanine, a suspected excitotoxin that overstimulates and destroys nerve cells. This compound causes a parkinsonism-like disease in macaques (Spencer et al, 1987). Other toxins have been proposed to be responsible for the disease, among them cycasin, another cycad toxin (Stone, 1993). 

The gastrointestinal flora may modify foreign compounds and either render them toxic to their host or assist in detoxication. An example of the former is cycasin, a compound in food made from cycad nuts that by itself is not toxic to rats. Hydrolysis by the rat s microflora generates metabolites, one of which is toxic. Germ-free rats suffer no toxic effects from ingested cycasin. 

Duncan, M. W. (1991). Role of the cycad neurotoxin BMAA in the amyotrophic lateral sclerosis-parkinsonism dementia complex of the western Pacific. Advances in Neurology 56,301-310. 

Kurland, L. T. (1972). An appraisal of the neurotoxicity of cycad and the etiology of amyotrophic lateral sclerosis on Guam. Federation Proceedings 31,1540-1542. Kusnetzov, V. B. (1988). Problem of olfaction reduction in Odontoceti toothed whales. Zhurnal Olschei Biologii 49,128-135. 

Pellmyr, O., Tang, W Groth, I., Bergstrom, L. G. and Thien, L. B. (1991). Cycad cone and angiosperm volatiles inferences for the evolution of insect pollination. Biochemical Systematics and Ecology 19 623-627. 

The unigeneric cycad family is found from Hast Africa to Japan and Australia. Other genera, formerly placed in this family, are now included in the Zamiaceae (q.v.) by some botanists Bowenia, Ence-phalarlox, Lepidozantia, Macrozamia, and Zttmia. Slangeria lias been separated by some authors into the Stangeriaceae. 

These cycads of the tropical and warm areas of America, Africa, and Australia contain a toxic principal macrozamine, which is carcinogenic. 

Brownson D. M., Mabry T. J., and Leslie S. W. (2002). The cycad neuiotoxic amino acid, fi-N-methylamino-l-alanine (BMAA), elevates intracellular calcium levels in dissociated rat brain cells. J. Ethnopharmacol. 82 159-167. 

Ince R G. and Codd G. A. (2005). Return of the cycad hypothesis-does the amyotrophic lateral sclerosis/parkinsonism dementia complex (ALS/PDC) of Guam have new implications for global health Neuropathol. Appl. Neurobiol. 31 345-353. 

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