Development of malaria parasites in mosquitoes fed with ookinetes suspended in defined media

Information concerning the specific nutritional requirements of malarial parasites developing in the mosquito host has been difficult to obtain, owing primarily to the complex nature of the blood meal that accompanies the parasites and the lack of success in culturing the complete invertebrate cycle ofPlasmodium in vitro. The present report describes a blood-free system for infecting mosquitoes with ookinetes ofPlasmodium berghei and for allowing the latter to develop into infective sporozoites. Ookinetes cultured in vitro were separated from blood proteins, suspended in defined medium, and fed toAnopheles stephensi mosquitoes through a membrane. The mosquitoes were then maintained on the same defined medium plus 5% sucrose. Infectivity of the parasites was demonstrated 17–19 days later by intracardial inoculation of the macerated mosquitoes into hamsters. This system makes it possible to evaluate nutritional factors that affect parasite development in the mosquito host under controlled conditions.This project was supported, in part, by the Public Health Service research grant AI-18345 from the National Institute of Allergy and Infectious Diseases to Prof. K. Maramorosch, and the Charles and Johanna Busch Memorial Fund at Rutgers, The State University of New Jersey.     

Malarial parasites complete sporogony in axenic mosquitoes

Summary To obtain sporogonic stages of malaria free from microbial contaminants for in vitro studies,Anopheles stephensi were reared under sterile conditions using a mosquito cell line as larval food. The adult females, kept in sterile humidified containers and allowed to engorge on parasitemic hamsters, supported the sporogonic development of the rodent malarial parasitePlasmodium berghei. In 10 experiments, the proportion of infected mosquitoes varied from 0 to 92%, and the geometric mean number of oocysts per female mosquito from 2.5 to 58,6, with a range of 1 to 548. The average number of salivary gland sporozoites per infected mosquito was determined by direct sporozoite counts in the pooled homogenate of the thoraces of all female mosquitoes. In five experiments, it varied from 2.7×10³ to 9.0×10³. The sterile sporozoites, harvested on day 19 or 20 after the infective blood meal, were as infective for rodents as nonsterile ones.Supported in part by Public Health Service research grant AI 18345 from the National Institute of Allergy and Infectious Diseases, by a grant from the Agency of International Development DSPE-5542-G-SS-3042-00, and by a Charles and Johanna Busch award.     

Malarial parasites complete sporogony in axenic mosquitoes

To obtain sporogonic stages of malaria free from microbial contaminants for in vitro studies, Anopheles stephensi were reared under sterile conditions using a mosquito cell line as larval food. The adult females, kept in sterile humidified containers and allowed to engorge on parasitemic hamsters, supported the sporogonic development of the rodent malarial parasite Plasmodium berghei. In 10 experiments, the proportion of infected mosquitoes varied from 0 to 92%, and the geometric mean number of oocysts per female mosquito from 2.5 to 58.6, with a range of 1 to 548. The average number of salivary gland sporozoites per infected mosquito was determined by direct sporozoite counts in the pooled homogenate of the thoraces of all female mosquitoes. In five experiments, it varied from 2.7 X 10(3) to 9.0 X 10(3). The sterile sporozoites, harvested on day 19 or 20 after the infective blood meal, were as infective for rodents as nonsterile ones.     

Niche width of parasites in species-rich and species-poor communities

Summary Niche width of ectoparasites of marine fishes, as measured by host range and microhabitat width, is not affected by the number of species in a community. There is no reduction in species numbers of Monogenea due to greater numbers of other parasite species, and frequencies of infection with Monogenea are greater in tropical, species-rich communities.Supported by grants from the Australian Research Grants Committee and the University of New England. M. Heap provided valuable technical assistance, and F. Roubal made his data onAcanthopagrus australis available to me.     

Aerobic glycolysis of normal tissues suspended in thoracic duct lymph

Riassunto La produzione aerobia di acido lattico da parte. di tessuti normali di ratto non viene ridotta o inibita dalla loro incubazione in un mezzo fisiologico quale la linfa di dotto toracico.     

Cell surface proteolytic activity of suspended embryonic cells isolated with and without proteolytic enzyme

Summary Although trypsin-disaggregated embryonic chick neural retina cells are incapable while EDTA-disaggregated cells are capable of immediate aggregation in culture, cells from both populations exhibit equally negligible levels of cell surface proteolytic activity as measured by substrate assay. The trypsin-induced lag does not appear, therefore, to depend upon adsorbed enzyme.     

Dye-binding assay for the determination of sub-milligram quantities of suspended solids in freshwater

Summary Clay and plankton particles from natural freshwater samples were collected on glass-fiber filters and stained with toluidine-blue to saturation at pH 8.6. The adsorbed dye was then eluted and quantified by spectrophotometry. The dye-binding capacity per dry weight was a consistent feature of the assemblage of particles contained in each sample, and varied very little between samples obtained from different water sources. This dye-binding assay is far more sensitive than the gravimetric determination of suspended solids.This research was carried out within the framework of the center for reservoirs research, sponsored by Mekorot Water Co., Israel.     

The role of platelets in the pathogenesis of cerebral malaria

Malaria is a major cause of morbidity and mortality in the developing world and cerebral malaria is responsible for the majority of malaria-associated deaths. There is a strong association between thrombocytopenia and outcome in malaria, suggesting a role for platelets in the pathogenesis of malaria. This thrombocytopenia is likely due to platelet activation possibly through an interaction between PfEMP1 on plasmodium and CD36 on platelets. Platelet activation by plasmodium has two potential consequences. It can lead to the formation of micro-aggregates of infected red blood cells and platelets which can occlude blood vessels and it also leads to binding to and activation of the endothelium.     

Changes in protein-bound sulfhydryl group concentration in the liver of rats fed cabbage

Zusammenfassung Eine statistisch signifikante Erhöhung der eiweissgebundenen SH-Stoffe, somit auch der totalen SH-Stoffe in der Leber mit strumigenem Kohl gefütterter Ratten, wurde festgestellt. Im Gehalt nicht eiweissbundener SH-Stoffe (SH-glutathion) in Leber und Blut nach Kohlverfütterung kam es zu keiner Veränderung.