Biomedical Engineering Reference
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a
b
c
10µm
10µm
10µm
d
e
10µm
10µm
FIGURE 2.3 (See color insert.)
Morphological diversity of microalgae: (a)
Actinocylus
octonarius
Ehrenb.
,
(b)
Biddulphia
biddulphiana
(Smith) Boyer, (c)
Thalassionema
nitzshioides
Grun., (d)
Rhizosolenia
setigera
Btw., (e)
Thalassiothrix longissima
Cleve & Grun.
a
b
c
10µm
10µm
10µm
d
10µm
FIGURE 2.4 (See color insert.)
Morphological diversity of microalgae: (a)
Ceratium
hirun-
dinella
(Muller) Dujardin, (b)
Ceratium
longipeps
(Bailey) Grun.
,
(c)
Ceratium trichoceros
(Ehrenberg) Kofoid, (d)
Gymnodinium sanguineum
Hirasaka.
However, a problem with several commonly used primers is that they are con-
structed theoretically and from an incomplete database of 18S rRNA sequences
from cultured organisms. Therefore, experiential testing is pivotal to confirm PCR
primer specificity prior to their use in environmental samples. Thus far, a large
number of primer sequences have been produced for amplification and sequencing
of ssu-rRNA genes. Some of them have been designed as taxa specific, whereas
others, designed to amplify all prokaryotic ssu-rRNA genes, are referred to as uni-
versal primers. Because the database of 18S rRNA gene sequences has grown, new
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