Apoptosis of chloroquine-resistant strain of Plasmodium berghei at asexual stages / 第二军医大学学报

ABSTRACT

Objective: To investigate the feature of crisis at asexual stages of chloroqine resistant strain (RC) of Plasmodium berghei . Methods: By means of optical microscope,transmission electron microscope and agarose electrophoresis, microscopic and ultramicroscopic architectures, and genomic DNA electrophoresis at asexual stages of the RC and chloroquine sensitive (N) strains of P. berghei with rising parasitemia and the RC strain of the parasite with declining parasitemia were observed in ICR mice. Results: Under microscope, different developmental stages asexual parasites with normal forms were found in blood smears from the mice infected by the N and RC strains with rising parasitemia, whereas there were a few of the asexual parasites most of which were contracted and vacuolated from the mice recovered from infection by the RC strain. Using electron microscope, intact cytoplasm membranes of the parasites paralleling with parasitophrous membrane of erythrocytes, nuclear laterad, obvious metabilic window and mitochondrions, ribosomes, endoplasmic reticulum in cytoplasm were recognized in erythrocytic stages of the RC and N strains with rising parasitemia. There were rhoptries in merozoites and food vacuoles in trophozoites of the N strain. Erythrocytic parasites of the RC strain from recovered mice with declining parasitemia were spherical or elliptical, with intact cytoplasm membrane, contracted nuclei and concentrated cytoplasm, without mitochondrion membranaceous structure and metabolic windows. The genomic DNA electrophoretogram of the RC strain parasites in the recovered mice showed a ladder pattern, which differed evidently from the parasites of the RC strain with rising parasitemia and the N strain which showed a single band. Conclusion: It is confirmed that crisis form of asexual stages of the RC strain is apoptosis.