title: First report on the occurrence of microcystins in planktonic cyanobacteria from Central Mexico.
abstract: Although toxic cyanobacteria are commonly described worldwide, only one recent paper on the toxicity of cyanobacteria in Mexico has been published reporting the occurrence of cylindrospermopsin and saxitoxins. Microcystins are the most commonly studied cyanotoxins in many countries and those that may cause the most dramatic problems in terms of human health. In this paper, we studied the occurrence of potentially toxic cyanobacteria in different ecosystems in Central Mexico. Samples were collected in natural lakes (Zumpango, Laguna Atotonilco and Cienega Chica), reservoirs (Los Angeles and Valle de Bravo), man-made channels (Cuemanco, Tlameleca) and urban lakes (Chapultepec). A multi-technique approach was applied by the use of molecular, immunological and chemical techniques. Cyanobacteria were found in all the sites, ranging from 1.6 x 10(3) cells/mL in Tlameleca to 7.5 x 10(6) cells/mL in Chapultepec Grande, representing between 67 and 100% of the total phytoplankton density. The concentration of total microcystins varied between 4.9 and 78.0 microg MC-LR eq/L. The results revealed the occurrence of MC-LR in all the sites analyzed by MALDI-TOF, and MC-FR, MC-RR and MC-H(4)YR in two sites. Most of the studied sites are used either as a source of drinking water, as a recreational area, or for agriculture irrigation purposes, so the risk for human health may be high if not properly monitored. This is the first report on the MC profiles and concentrations in blooms collected in Mexico.
authors.affiliation: Departamento de Biologia, Faculdade de Ciências, Universidade do Porto, Edifício FC4, Rua do Campo Alegre, 4169-007 Porto, Portugal. vmvascon@fc.up.pt
authors.forename: Vitor
authors.initials: V
authors.lastname: Vasconcelos
authors.forename: António
authors.initials: A
authors.lastname: Martins
authors.forename: Micaela
authors.initials: M
authors.lastname: Vale
authors.forename: Agostinho
authors.initials: A
authors.lastname: Antunes
authors.forename: Joana
authors.initials: J
authors.lastname: Azevedo
authors.forename: Martin
authors.initials: M
authors.lastname: Welker
authors.forename: Oscar
authors.initials: O
authors.lastname: Lopez
authors.forename: Gustavo
authors.initials: G
authors.lastname: Montejano
mesh_terms: D001483:Base Sequence; D000458:Cyanobacteria / Q000737:chemistry*; D017931:DNA Primers; D004797:Enzyme-Linked Immunosorbent Assay; D008800:Mexico; D052998:Microcystins / Q000302:isolation & purification*; D010933:Plankton / Q000737:chemistry*; D016133:Polymerase Chain Reaction; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D017931:DNA Primers; D052998:Microcystins