Nucleus

 

The major organel of an amoeba is the nucleus. Its main function is to direct cell activities, as reproduction, eating and grow, which it does by causing the production of specific enzymes to carry out chemical reactions.  It contains the amoeba’s DNA, the "blueprint" of cell function, which instructs the cell how to make those enzymes.
Each amoeboid cell contains at least one nucleus. Larger cells are often multinucleate.
The morphology of the nucleus, its size and the number can be useful differential characters. According to the classification of Raikov (1982) two principal types of nuclei are found in amoebae:

  1. vesicular nuclei with one, often central nucleolus, sometimes with a few additional very small nucleoli;
  2. ovular nuclei with several to many small nucleoli (Fig. 1).

 

nucleus
nucleus
nucleus
nucleus
Fig. 1. Left: vesicular nuclei of Difflugia biconcava and D. gramen. Right: ovular nuclei of Difflugia amphora and D. distenda.

 

Below: photomicrographs of some typical nuclei:

 

Cucurbitella mespilliformis
Difflugia spec. nucleus
Cucurbitella vlasinensis
Cucurbitella mespilliformis
Difflugia gramen
Cucurbitella vlasinensis
Cucurbitella vlasinensis
Cucurbitella vlasinensis
Cucurbitella vlasinensis
Difflugia microclaviformis
Pelomyxa spec.
Trichamoeba myakka
Difflugia lobostoma
Difflugia capreolata
Difflugia bidens
Difflugia lobostoma
Difflugia capreolata
Difflugia bidens
Difflugia gramen
Difflugia tuberculata
Difflugia gramen
Difflugia tuberculata
Difflugia urceolata
Mayorella augusta
Polychaos annulatum
Amoeba proteus
Mayorella augusta
Polychaos annulatum
Amoeba proteus
Mayorella augusta
 
 
Difflugia amphora