Ka. Mikrjukov et Ap. Mylnikov, A study of the fine structure and the mitosis of a lamellicristate amoeba,Micronuclearia podoventralis gen. et sp nov (Nucleariidae, Rotosphaerida), EUR J PROT, 37(1), 2001, pp. 15-24
A study of the fine structure and the mitosis of a new member of the naked
filose amoebae (Nucleariiadae, Rotosphaerida), Micronuclearia podoventralis
is performed. The amoeba has a single large dictyosome adjoining to the nu
cleus, 2-4 spherical mitochondria with lamellate cristae, its cell membrane
is supported by a thin proteinous pseudopellicle. M. podoventralis has nor
mally a single branching filopodium or 2-4 smaller ones with bases that lie
close to each other. The bases of the filopodia arise from the middle of a
shallow depression, the curved edge of which is supported by a mucopolysac
charide layer under the plasma membrane and by a thin cuticle over it. The
mitosis of M. podoventralis occurs as an open orthomitosis, but the microtu
bules appear inside the nucleus at prophase before dissolution of the nucle
ar envelope and before disaggregation of the nucleolus. The nuclear envelop
e has broken down by metaphase by which time sister dictyosomes are found a
t the poles of the spindle. The phylogenetic source of the lamellicristate
sarcodines is discussed.