Infectivity of cultured Plasmodium falciparum gametocytes to mosquitoes.

Various factors that may influence routine and high levels of mosquito infection with cultured Plasmodium falciparum gametocytes are considered in this paper. One of the most important is the choice of an appropriate isolate, with facilities for cryopreservation and a good technique for initiation of cultures. The use of automated culture systems with strict adherence to detail and routine has eliminated much of the variability. The quality of the serum used for the culture of gametocytes and inclusion in the feed material for mosquitoes is of the highest importance. Blood collection for culture purposes must preferably involve alcohol as an antiseptic for cleaning donor skin or suitable receptacles. Mosquito blood meals should not include plasma with citrate phosphate dextrose or sera collected in microtainer tubes or from volunteers on proguanil-chloroquine prophylaxis. Sera of individuals on chloroquine alone do not influence transmission. Haematocrits of from 5 to 10% permit the culture of equally infective gametocytes. It was impossible to predict the outcome of an infection in mosquitoes based on the number of female gametocytes or gametes. Within any experiment, the oocyst load initially increased, followed by a decline with progressively lower numbers of gametocytes accompanied by a progressive increase in the efficiency of transmission. Some of the variability of mosquito infection within an experiment was due to individual differences in the speed of blood digestion of the mosquitoes. A new membrane feeder is described with three different sizes to accommodate a variety of goals.(ABSTRACT TRUNCATED AT 250 WORDS)

Sporozoite load of mosquitoes infected with Plasmodium falciparum.

In the laboratory, mosquitoes given a second blood meal 5-11 d after an infective one have more sporozoites in their salivary glands than do those given a single infective blood meal only. The presence of specific anti-sporozoite antibody in the second blood meal does not reduce the number of sporozoites in salivary glands. On the contrary, the presence of the raised immunoglobulin levels--even non-specific ones--may result in higher gland infections. Oocyst maturation is extremely asynchronous in mosquitoes given a single blood meal, the maturation time being 10-22 d or more. The explanation for the increased density of sporozoites in salivary glands in mosquitoes having a second blood meal may be acceleration of oocyst maturation. Multiple blood meals are a normal event for infectious mosquitoes in nature, and therefore have no special epidemiological significance. However, in the laboratory a second blood meal could be a simple procedure for increasing the efficiency of sporozoite production.

Non-mutagenicity of 27 aliphatic acrylate esters in the Salmonella-microsome test.

The mutagenicity of 27 acrylate esters was assessed in the Salmonella-microsome assay. Methyl, ethyl, butyl, t-butyl, pentyl, neopentyl, hexyl acrylate and methacrylate and 2-hydroxyethyl methacrylate were tested; furthermore ethanediol, butanediol, pentanediol, neopentanediol, hexanediol and diethyleneglycol diacrylate and dimethacrylate. None of these 27 acrylate esters appeared to be mutagenic in the standard Ames assay with TA1535, TA1537, TA1538, TA98 and TA100, both with and without Aroclor 1254 or phenobarbital-induced S9 mix. A liquid incubation assay of methyl methacrylate, methyl, butyl and hexyl acrylate with TA100 neither gave any indication of a mutagenic activity of these compounds.