Publication Date:
2021-05-19
Description:
Today, due to population increase and anthropogenic activities together with sewage and agricultural waste
water entrance, aquatic ecosystems have been exposed to high pollutions. Phytoplankton is a group of waterfloating
algae that have crucial roles in providing nutrients and oxygen for other organisms, nitrogen and CO2
fixation.
These organisms are considered as primary producers in aquatic ecosystems. They are found in various water
habitats all over the world, affected by environmental variables such as pH, light and temperature and used for
determination of water pollution degree and quality.
Phytoplankton composition and density may be used as a complementary indicator of water trophy state.
Phytoplankton communities indicate short and long term variations of aquatic systems. One of the most obvious
problems in freshwater ecosystems is algal bloom or over growth of some blue- green algae which can decrease
oxygen, and in some cases bring about toxin excretion and fish and human kills.
In addition, many of bloom forming cyanobacteria produce secondary metabolites which can create sever
poisoning in mammals including human. The genus Microcystis is a key bloom forming cyanobacteria in aquatic
ecosystems. Populations of this genus form intense blooms in water bodies that has attracted more attentions in
recent years. Various species of this alga have been distributed in stagnant and eutroph freshwater around the
world.
Microcystis has been defined by genetic criteria such as 16S rRNA molecular sequencing, but its classification in
levels lower than genus is unclear and the presence of its classical morphospecies is doubtful. However, this
genus creates sever blooms in eutrophic waters all over the world and many species produce toxins. Therefore,
identification of its natural diversity in the levels lower than genus has high importance. However, several
characteristics of Microcystis morphotypes which are classified a traditional species, actually are present and
observed in different regions of the world. At present, they can be considered as morphospecies that belong to
one genotype and have similar ecology. These traditional species with definite phenotypic and ecophysiological
characteristics cannot be eliminated completely. Their identification is essential for ecological and
ecotoxicological studies.
Interistic transcribed separator (ITS) gene is a section of genome which is located between 16s rRNA and 23s
genes. This gene has more heterogeneity than 16s rRNA; so it is used to identify many genera of cyanobacteria.
The Aras reservoir located in the north-west of Iran plays important roles as fisheries, drinking and agricultural
water supply and recreational activities in the region. The present thesis was undertaken to: analyze the
Microcystis sp. populations by molecular methods such as ITS in Aras Reservoir.
Samples for molecular analysis were collected from 10 sampling sites on 18 August 2013.
Samples for molecular study of Microcystis were collected from two different depths (surface and 1 m depth)
and transferred to laboratory without any treatments. Microscopic images of Microcystis were sent to professor
Komárek and was confirmed.
Description:
Iranian Fisheries Science Research Institute
Description:
Published
Keywords:
Molecular
;
Barcoding
;
Microcystis aeruginosa
;
ITS-2
;
Gene
;
Population
;
Aquatic
;
16S rRNA
Repository Name:
AquaDocs
Type:
Report
,
Refereed
Format:
44pp.
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