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V.$LÓPEZ$RODAS$y"col.$

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aisladas*de*M.$aeruginosa*aisladas*de*cuatro*blooms*diferentes*en*tres*depósitos*de*
abastecimiento*de*agua*y*en*una*laguna,*así*como*una*gran*cantidad*de*colonias*de*
M.$ aeruginosa* directamente* recogidos* de* muestras* de* campo.* Todas* las* cepas* no*
tóxicas*de*M.$aeruginosa*fueron*marcadas*positivamente*con*la*lectina*UEA.1**y*por*
varias*otras*lectinas.*Sin*embargo,*las*cepas*más*tóxicas*permanecieron*sin*marcar.*
Este* procedimiento* también* tuvo* éxito* en* muestras* de* campo.* Aunque* existen*
otras* técnicas* que* permiten* la* diferenciación* entre* cepas* tóxicas* y* no* tóxicas,*
ninguna*es*tan*rápida*y*simple*como*el*marcaje*por*lectinas.*

Palabras$clave:!Lectina;!Microcystis)aeruginosa;!Toxicidad.!

1.*INTRODUCTION*
Toxic!cyanobacterial!blooms!in!eutrophic!lakes,!rivers,!and!reservoirs!have!

been!reported!during!the!last!decades!all!over!the!world!(1?4).!These!toxic!blooms!
have! caused! the! death! of! livestock! and! wildlife! and! illness! and! even! death! in!
humans!(5,!6).!For!example,!over!50!patients!at!a!dialysis!center!in!Caruaru,!Brazil,!
died! from! February! to! September! 1996! of! acute! liver! failure.! Although! the!
cyanobacterial! species! responsible! have! not! yet! been! identified! completely,!
microcystins! produced! by! cyanobacteria! were! detected! in! water! from! the!
reservoir!and!the!dialysis!center,!and!in!serum!and!liver!tissue!of!affected!patients!
(7).! Other! incidents! have! also! been! reported! in! other! countries! such! as! China,!
where! cyanobacterial! blooms! are! a! great! health! problem! (8?10).! Moreover,! long?
term!exposure!to!low!levels!of!microcystins!in!drinking!water!could!be!a!risk!factor!
for!liver!and!colorectal!cancer!in!Europe!(11).!The!World!Health!Organization!has!
set! a! provisional! guideline! value! of! 1.0! µg.liter?1! for! this! toxin! (10).! In! addition,!
cyanobacterial!blooms!pose!a!challenge!for!wildlife!conservation!because!they!are!
caused! of! repeated! mass! mortalities! of! fishes! and! water! birds! in! wildlife! refuges!
(13?16).!!

Although! more! than! 40! species! of! cyanobacteria! produce! of! cyanotoxins,!
Microcystis)aeruginosa!(Kützing)!Kützing!is!considered!the!most!prevalent!harmful!
species! in! freshwater! ecosystem! (1).! In! fact! M.)aeruginosa! is! the! most! important!
cause!of!toxic!cyanobacterial!blooms!affecting!humans!and!animals!in!inland!water!
systems!worldwide!(1,!7,!17?20).!!

Microcystins! are! a! group! of! monocyclic! heptapeptide! hepatotoxins!
produced! by! M.) aeruginosa,! which! are! the! end! products! of! a! secondary! metabolic!
pathway!synthesized!non?ribosomally!by!multienzymes!comprising!non?ribosomal!
peptide! synthetases,! polyketide! synthases! and! tailoring! enzymes! (21).! These!
peptides!are!inhibitors!of!serine?treonine!protein!phosphatases!1!and!2A!(22?26).!!

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