The effects of host diet on Plasmodium yoelii nigeriensis.

A comparative study carried out on infected mice to investigate the effect of host diet on Plasmodium yoelii nigeriensis showed that concentrations of blood protein, hemoglobin, and erythrocytes began to decrease in infected mice on day 2 after inoculation and reached the lowest levels on day 8. The greatest decrease was among mice fed on protein-rich mouse cubes, whereas the least decrease was among mice fed on cassava meal. Inflammation of the spleens and livers of infected mice also was noticed. Leucocyte numbers and parasitemia in infected mice reached their peaks on day 8. Again, the greatest prevalence of these abnormalities was apparent among mice whose diet contained the highest amount of protein in comparison to the other diets used in this study. The abnormalities decreased proportionately among the other groups of infected mice, corresponding to the protein content of their various diets. Mice fed on cassava meal, with the lowest content of protein, had the fewest abnormalities. Elevated body temperature, characteristic of severe malaria, and extensive liver damage were highest among mice with the greatest amount of protein in their diet. In view of these observations, it was surmised that during malaria, host diets high in protein heighten the severity of this disease.

Extrusion of the residual body in spermatids of Ancylostoma caninum (Nematoda, Strongyloidea).

Transmission electron microscopy reveals that the spermatocytes of the hookworm Ancylostoma caninum contain an abundance of Golgi complexes, ribosomes, specialized membranous organelles, and long strands of smooth endoplasmic reticulum. These organelles remain abundant until the early spermatid stage of sperm development, when they reach their maximum abundance and maturity and the production of new ones ceases. Golgi complexes, ribosomes, and excess SER, which are not functional after this stage, become segregated and confined to the posterior portion of the spermatid in a polar lobe. Later, the polar lobe together with excess cytoplasmic matrix is bound by a membrane and dissociated from the spermatid as a residual body. The spermatid is then devoid of Golgi complexes and ribosomes. Formation of residual bodies as sperm cells mature may be considered a type of cell excretion.

The function of microtubules during spermatogenesis of Ancylostoma caninum.

Ancylostoma caninum spermatogonia appeared as unspecialized cells with large nuclei and little cytoplasm when examined by electron microscopy. Mitochondria and ribosomes were numerous but endoplasmic reticulum of either the rough or smooth variety was rarely observed. Microtubules were abundant but were mostly concentrated in areas where the cells connected with a central cytoplasmic core, or rachis. Microtubules present elsewhere in the cytoplasm were not associated with any particular organelle. In spermatocytes, microtubules became numerous and formed the spindle apparatus during the rapid meiotic divisions. Following the meiotic divisions the nuclei of the resulting spermatids were devoid of a nuclear envelope, and the chromatin became highly condensed. At this time, the microtubules surrounded the elongating nucleus as it became confined to the tapering, posterior portion of the spermatid. These observations indicate that microtubules are involved in determining this final morphological appearance of Ancylostoma spermatids. However, there is no evidence to indicate the microtubules are assembled into motile organelles to be utilized by the ameboid in utero spermatozoa.

Development and fate of the membranous organelles in spermatozoa of Ancylostoma caninum.

During development membranous organelles first appeared in the primary spermatocytes of Ancylostoma. They were derived from the Golgi as two separate components. One component, an electron-dense spheroid, quickly fused with other newly-formed cup-shaped, membranous structures to form the asymmetrical organelles. Initially the membranous organelles had a homogeneous matrix but later became filled with quantities to 6- 8-nm filaments. Following the meiotic reduction divisions each cell assumed a bipolar configuration. The membranous organelles and mitochondria were confined to the broad anterior region while the non-membrane bound nucleus became located in the narrow posterior region. Golgi membranes, endoplasmic reticulum, and numerous ribosomes were sloughed from the main cell body. The filaments lost their association with the membranous organelles and attached to the plasma membrane while the membranous portion of each organelle became progressively more complex and assumed a peripheral position in the cytoplasm. The resulting spermatid, with its condensed, posteriorly-projected nucleus, and broad anterior cytoplasm, had a tadpolelike appearance. Subsequent to deposition in the female uterus the membranous organelles fused with the plasma membrane and the mature spermatozoa became pleomorphic and moved in an ameboid manner. Because the pseudopods in the mature cell originated in those areas where the filaments previously attached to the plasma membrane it is surmised that the filaments consist of, or contain, actin. The significance of the fusion of the membranous organelles with the sperm plasma membrane, however, remains unknown.