1. The document summarizes a journal article that studied the influence of nitrogen on heterocyst production in blue green algae. 2. The study found that heterocyst numbers increased when algae were grown in nitrate-free medium, providing evidence that heterocysts are involved in nitrogen fixation. 3. Heterocyst numbers were found to be regulated by changes in nitrogen sources in the atmosphere and medium, with the lowest numbers occurring when ammonium was present and the highest with nitrogen gas present.

1. SYNTHESIS OF JOURNAL
2. The Influence of Nitrogen on Heterocyst Production in Blue Green Algae
Name : Citra Amalia (1100167) Date of Presentation : Wednesday, 23 April 2014
Nenden Permas H. ()
Shofwa Widdina ()
Name of
Journal
Authors Materials Method Result Conclusion Glossarium
Limnology
and
Oceanography
Roann E. Ogawa
and John F. Carr
(U.S. Burcau of
Commercial
Fisheries,
Biological
Laboratory, Ann
Arbor, Michigan
48107)
The algae used in
this research are:
-Blue green algae
(Anabaena
variabilis and
Mycrocystis
aeruginosa NRC-
1, Anabaena
cylindrica B629,
A. inequalis 381)
- French squares /
Erlenmeyer
flasks
-culture medium
(chu no.10)
-nitrate free
media
Heterocysts of A.
variabilis were
counted
↓
Sufficient lengths
were measured
↓
Counting the
heterocysts/unit
length of filament
(quantifying
&comparing)
↓
Measured veg. cell
length
↓
tested through
bubbling air
↓
All experiment
repeated 2/3 times
on different dates
↓
Average of number
Heterocyst
number regulated
by : changes in
nitrogen sources
(lowest when
NH4-N, highest
in N2-N)in the
atmosphere,
controlling the
concentration of
NO3-N in the
medium, the
absence of
combined
nitrogen and the
presence of
phosphate.
A series of
experiments on
heterocyst
production in
Anabaena
variabilis
provides some
strong indirect
evidencefor the
role of heterocyst
in nitrogen
fixation. From
the algae tested
(Anabaena
variabilis, A.
inequalis, A.
cylindrical, etc)
grew in nitrate
free medium,
accompanied by
an increase in
heterocyst.
Cyanophyceae:or blue-green
algae are a group
of photosynthetic
microorganisms that are
more closely related to
the bacteria than to
higher (eukaryotic) algae
Heterocyst:Heterocyst is
a cell that is nitrogen
fixing. It is a specialised
cyanobacterial cell that
carries the function of
nitrogen fixing.
N-fixation : Fixed
nitrogen is nitrogen gas,
N2, that has been
converted to ammonia
(NH3, an ammonium ion
(NH4, nitrate (NO3, or
another nitrogen oxide
so that it can be used as a
nutrient by organisms.