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.