Slime Moulds - Cellular

Description:

Cellular slime moulds are found in humus containing upper layers of damp soil. The uninucleated and haploid cells of slime moulds are called myxamoebae. Myxamoebae are amoeba like cells. These cells are covered by plasma membrane.

Under unfavourable conditions a myxamoeba secretes a rigid cellulose wall to form the microcyst. On the onset of favourable conditions the microcyst wall ruptures to release myxamoeba.

Life cycle of Cellular Slime Moulds

• Pseudoplasmodium − When food supply is exhausted the amoeboid cells get aggregated without any fusion. The stimulus for the aggregation process is due to release of cyclic adenosine monophosphate (cyclic AMP) from the amoeboid cells. These aggregated mass of cells is known as pseudoplasmodium.

• Sporangium − The aggregated cells of pseudo-plasmodium differentiate and migrate to form a stalked sporocarp. The sporocarp bears a sporangium at its terminal end.

• Spores − The cells present inside the sporangium become rounded and are surrounded by the cellulose wall to form the spores. The spores germinate to produce a single naked amoeba like cells called myxamoeba.

• Sexual Reproduction − Sexual reproduction in slime moulds is controversial. In this process the myxamoeba form clusters. The central myxamoeba of the cluster engulfs a surrounding myxamoeba to become larger structure which forms a thick wall to form the zygote. This zygote is called microcyst.