Biomagnification of cyanobacterial neurotoxins and neurodegenerative disease among the Chamorro people of Guam

Cox, Paul Alan; Banack, Sandra Anne; Murch, Susan J.

doi:10.1073/pnas.2235808100

Cited by 546 publications

(411 citation statements)

References 18 publications

Supporting

Mentioning

389

Contrasting

Unclassified

Order By: Relevance

“…Cyanobacteria also can negatively affect domestic and wild animals as well as human health since they have the potential to produce toxins (see overview Merel et al 2013), and numerous animal and human intoxications by cyanobacterial toxins have been reported (e.g. Kuiper-Goodman et al 1999;Cox et al 2003;Griffiths and Saker 2003;Hilborn et al 2007). Hence, cyanobacterial dominance in water systems can have serious economical and societal consequences as it impedes important ecosystem services of inland waters including recreational use, aquaculture, water usage for irrigation and drinking water usage (Paerl and Huisman 2009;Ibelings et al 2014).…”

Section: Introductionmentioning

confidence: 99%

Artificial mixing to control cyanobacterial blooms: a review

et al. 2015

View full text Add to dashboard Cite

Artificial mixing has been used as a measure to prevent the growth of cyanobacteria in eutrophic lakes and reservoirs for many years. In this paper, we give an overview of studies that report on the results of this remedy. Generally, artificial mixing causes an increase in the oxygen content of the water, an increase in the temperature in the deep layers but a decrease in the upper layers, while the standing crop of phytoplankton (i.e. the chlorophyll content per m 2 ) often increases partly due to an increase in nutrients entrained from the hypolimnion or resuspended from the sediments. A change in composition from cyanobacterial dominance to green algae and diatoms can be observed if the imposed mixing is strong enough to keep the cyanobacteria entrained in the turbulent flow, the mixing is deep enough to limit light availability and the mixing devices are well distributed horizontally over the lake. Both models and experimental studies show that if phytoplankton is entrained in the turbulent flow and redistributed vertically over the entire depth, green algae and diatoms win the competition over (colonial) cyanobacteria due to a higher growth rate and reduced sedimentation losses. The advantage of buoyant cyanobacteria to float up to the illuminated upper layers is eradicated in a wellmixed system.

show abstract

Section: Introductionmentioning

confidence: 99%

Artificial mixing to control cyanobacterial blooms: a review

et al. 2015

View full text Add to dashboard Cite

show abstract

“…Moreover, several bloom-forming cyanobacteria produce toxins, causing serious and sometimes fatal liver, digestive and neurological diseases in birds and mammals, including humans (Carmichael, 2001;Cox et al, 2003;Codd et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

Genetic diversity of inorganic carbon uptake systems causes variation in CO2 response of the cyanobacterium Microcystis

et al. 2013

View full text Add to dashboard Cite

Rising CO 2 levels may act as an important selective factor on the CO 2 -concentrating mechanism (CCM) of cyanobacteria. We investigated genetic diversity in the CCM of Microcystis aeruginosa, a species producing harmful cyanobacterial blooms in many lakes worldwide. All 20 investigated Microcystis strains contained complete genes for two CO 2 uptake systems, the ATP-dependent bicarbonate uptake system BCT1 and several carbonic anhydrases (CAs). However, 12 strains lacked either the high-flux bicarbonate transporter BicA or the high-affinity bicarbonate transporter SbtA. Both genes, bicA and sbtA, were located on the same operon, and the expression of this operon is most likely regulated by an additional LysR-type transcriptional regulator (CcmR2). Strains with only a small bicA fragment clustered together in the phylogenetic tree of sbtAB, and the bicA fragments were similar in strains isolated from different continents. This indicates that a common ancestor may first have lost most of its bicA gene and subsequently spread over the world. Growth experiments showed that strains with sbtA performed better at low inorganic carbon (C i ) conditions, whereas strains with bicA performed better at high C i conditions. This offers an alternative explanation of previous competition experiments, as our results reveal that the competition at low CO 2 levels was won by a specialist with only sbtA, whereas a generalist with both bicA and sbtA won at high CO 2 levels. Hence, genetic and phenotypic variation in C i uptake systems provide Microcystis with the potential for microevolutionary adaptation to changing CO 2 conditions, with a selective advantage for bicA-containing strains in a high-CO 2 world.

show abstract

“…We previously reported that BMAA is produced by cyanobacteria of the genus Nostoc, which are root symbionts of cycads (1). BMAA is then biomagnified in both the cycad seeds and the flying foxes that forage on them.…”

mentioning

confidence: 99%

“…Consumption of flying foxes by the Chamorro people has been implicated as a delivery mechanism of relatively high doses of BMAA in the Chamorro diet (6,7). Support for this hypothesis has come from the findings of high levels of BMAA in Guam flying foxes (8) and the discovery of BMAA within brain tissues of Chamorro patients who have died of ALS͞PDC in Guam (1).…”

mentioning

confidence: 99%

A mechanism for slow release of biomagnified cyanobacterial neurotoxins and neurodegenerative disease in Guam

Murch

Cox

Banack

2004

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

368

326

View full text Add to dashboard Cite

As root symbionts of cycad trees, cyanobacteria of the genus Nostoc produce ␤-methylamino-L-alanine (BMAA), a neurotoxic nonprotein amino acid. The biomagnification of BMAA through the Guam ecosystem fits a classic triangle of increasing concentrations of toxic compounds up the food chain. However, because BMAA is polar and nonlipophilic, a mechanism for its biomagnification through increasing trophic levels has been unclear. We report that BMAA occurs not only as a free amino acid in the Guam ecosystem but also can be released from a bound form by acid hydrolysis. After first removing free amino acids from tissue samples of various trophic levels (cyanobacteria, root symbioses, cycad seeds, cycad flour, flying foxes eaten by the Chamorro people, and brain tissues of Chamorros who died from amyotrophic lateral sclerosis͞ Parkinsonism dementia complex), we then hydrolyzed the remaining fraction and found BMAA concentrations increased 10-to 240-fold. This bound form of BMAA may function as an endogenous neurotoxic reservoir, accumulating and being transported between trophic levels and subsequently being released during digestion and protein metabolism. Within brain tissues, the endogenous neurotoxic reservoir can slowly release free BMAA, thereby causing incipient and recurrent neurological damage over years or even decades, which may explain the observed long latency period for neurological disease onset among the Chamorro people. The presence of BMAA in brain tissues from Canadian patients who died of Alzheimer's disease suggests that exposure to cyanobacterial neurotoxins occurs outside of Guam.biomagnification ͉ cyanobacteria ͉ cycad ͉ symbiosis ͉ ALS͞PDC

show abstract

Biomagnification of cyanobacterial neurotoxins and neurodegenerative disease among the Chamorro people of Guam

Abstract: We here report biomagnification (the increasing accumulation of bioactive, often deleterious molecules through higher trophic levels of a food chain) of the neurotoxic nonprotein amino acid ␤-methylamino-L-alanine (

Cited by 546 publications

References 18 publications

Artificial mixing to control cyanobacterial blooms: a review

Artificial mixing to control cyanobacterial blooms: a review

Genetic diversity of inorganic carbon uptake systems causes variation in CO2 response of the cyanobacterium Microcystis

A mechanism for slow release of biomagnified cyanobacterial neurotoxins and neurodegenerative disease in Guam

Contact Info

Product

Resources

About