Biology Reference
In-Depth Information
(C)
Figure 4
:
Cylindrospermopsis raciborskii
, straight morphotype (A),
Raphidiopsis curvata
(B) and
Anabaena circinalis
(C). Pictures
A and B courtesy Roger Burks (University of California at Riverside), Mark Schneegurt (Wichita State University) and
Cyanosite (www-cyanosite.bio.purdue.edu). Picture C courtesy P. Znachor, Laboratory of Phytoplankton Ecology, Institute
of Hydrobiology, Biology Centre ASCR, Na Sádkách, 37005 České Budějovice, Czech Republic (www.FytoPlankton.cz).
(Craig
et al
., 1993; Azevedo
et al
., 1994; Bateman
et al
., 1995; Namikoshi
et al
., 1995; Diehnelt
et al
.,
2006). Table 2 summarizes the various MCs that show variations at Xaa and Zaa positions.
Besides changes in L-amino acids at Xaa and Zaa positions, the variation in MCs is also due
to demethylation in amino acids 3 and/or 7, modifi cation of Adda and changes in amino acids at
1, 6 and 7 positions (Rinehart
et al
., 1994; Sivonen, 1996). These variants of MCs are described here
and presented in Table 3. The substitution of β-methylaspartic acid and N-methylhydroalanine by
isoaspartic acid and dehydroalanine, respectively in
O
.
agardhii
resulted in the formation of [D-Asp
3
,
Dha
7
] MC-RR (Krishnamurthy
et al
., 1989; Luukkainen
et al
., 1993). The same MC variant was also
reported in
Anabaena
sp. strain 202A1 (Sivonen
et al.
, 1992a). New variants of MCs that have a
modifi ed Adda, i.e. DMAdda (
O
-demythylAdda) and ADMAdda (
O
-acetyl-
O
-demythylAdda)
have further been isolated and characterized (Namikoshi
et al
., 1991). Thus [DM Adda
5
] MC-LR was
reported from
Nostoc
sp. strain 152 (Sivonen
et al
., 1990a) and
Nostoc
sp. strain IO-102-I (Oksanen
et
al
., 2004). Likewise, [ADM Adda
5
] MC-LR was detected in
Microcystis
spp. (Namikoshi
et al
., 1992a),
Nostoc
sp. strain 152 (Sivonen
et al
., 1990, 1992b) and
Nostoc
sp. strain IO-102-I (Oksanen
et al
., 2004).
