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D) β-N-methylamino-L-alanine (BMAA): BMAA is a non-protein amino acid (Fig. 21) fi rst detected
in the cycad seeds where it is suggested to give chemical protection to the plant against herbivore
consumption. However, BMAA was also found in the cyanobacterial symbiont in the coralloid roots
of cycas. In the Guam ecosystem, biomagnifi cation of BMAA has assumed alarming proportions
(Cox et al ., 2003). BMAA from the cyanobacterium Nostoc gets accumulated in the seeds of cycads.
The seeds are in turn eaten by fl ying foxes. The fl ying foxes are a delicacy for the Chamarro people
of Guam. Apart from fl ying foxes, Chamarros also use cycad seed fl our. At each trophic level, BMAA
gets magnifi ed 100-folds in its concentration. There is a 10,000-fold increase in the concentration of
BMAA from the fi rst trophic level ( Nostoc ) to fl ying foxes. Thus Chamarros accumulate BMAA in their
brain tissue that leads to degenerative diseases such as amotrophic lateral sclerosis/Parkinsonism-
dementia complex (ALS/PDC). The incidence of these diseases among Chamarro people of Guam
is 50-100 times higher than at other places. BMAA is bound to proteins in the body and it is released
slowly. As it is released, it gets incorporated into the amino acid sequences of proteins.
Cox et al . (2005) reported that BMAA is produced by 95% of the cyanobacteria tested belonging
to all major taxonomic groups. BMAA is also found in other cyanobacterial-plant symbioses such
as Azolla fi liculoides and Gunnera kauaiensis . Cox et al . (2005) concluded that (i) the ability to produce
BMAA by most of the cyanobacterial species examined suggests that this is a very highly conserved
feature, (ii) the production of BMAA is not a consistent feature and it is a function of growth
conditions and/or life cycle stages, (iii) symbiosis is not a pre-requisite for BMAA production, (iv)
the magnitude to which human beings are exposed to BMAA can be gauged by the occurrence of
marine blooms of Trichodesmium thiebautii and T . erythraeum in the Baltic Sea and other oceans; and
the occurrence of Prochlorococcus in tropical and subtropical waters, and (v) in all toxicity studies,
the assay of BMAA would be helpful in understanding its role in pathological symptoms.
E) Toxins from L. majuscula : L . majuscula is a good source of secondary metabolites. As many as 100
such substances have been identifi ed from different isolates of this organism distributed all over the
world. Their production cannot be correlated to any specifi c geogaphical location (Gerwick et al .,
2001) and samples of L . majuscula from Guam have yielded diverse metabolites such as indanone
metabolites (Nagle et al ., 1996), lyngbyastatins (Harrington et al ., 1998; Luesch et al ., 2001; Williams et
al ., 2003), malyngolide (Cardellina et al ., 1979), majusculamides (Marner and Moore, 1977), pitiamide
(Nagle et al ., 1996) and peptolides (Luesch et al ., 2001). Toxicity studies on these metabolites are not
available. A Jamaican strain of L . majuscula is known to produce jamaicamide and two regulatory
proteins have been suggested to be involved in secondary metabolism and complementary chromatic
adaptation (Jones et al ., 2009).
Tropical marine species of Lyngbya and Symploca have been compared for diversity of their
morphological, chemical and genetic features. Characterization based on 16S rDNA analysis did
not reveal any relationship between morphological and chemical divergence on the one hand and
NH 2
NH
OH
H 3
C
O
Figure 21: Structure of β-N-methylamino-L-alanine (BMAA).
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